Interpretation and Correlation of Viscometric Data
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 NON-NEWTONIAN FLUID BEHAVIOR
4.1 Introduction
4.2 Classification of Non-Newtonian Fluids
4.3 Caution
5 VISCOMETER MEASUREMENTS FOR
TIME-INDEPENDENT FLUIDS
5.1 Concentric Cylinder Viscometers
5.2 Cone and Plate Viscometers
5.3 Parallel Plate Viscometer
5.4 Tube or Capillary Viscometer
5.5 Checks for Consistency of Data and Interpretation
5.6 Estimate of Process Shear Rate
6 MODEL FITTING TO FLOW CURVES
6.1 Power Law
6.2 Bingham Plastic
6.3 Direct use of Numerical Data
6.4 Rheological Models Involving Temperature Dependence
7 CHARACTERIZATION OF TIME-DEPENDENT LIQUIDS
7.1 Sample Loading
7.2 Tests at Constant Shear Rate
7.3 Dynamic Response Measurement
7.4 Changes in Shear Rate
7.4 Concluding Remarks
8 TECHNIQUES FOR CHARACTERIZATION OF
VISCOELASTIC LIQUIDS
8.1 Stress Relaxation
8.2 Oscillatory Shear Measurements
8.3 Normal Force Measurement
8.4 Elongational Viscosity Measurement
9 NOMENCLATURE
10 BIBLIOGRAPHY
APPENDICES
A EQUATIONS FOR VISCOMETERS
A.1 EQUATIONS FOR CONCENTRIC CYLINDER
VISCOMETERS
A.2 EQUATIONS FOR CONE AND PLATE VISCOMETERS
A.3 EQUATIONS FOR PARALLEL PLATE VISCOMETER
A.4 EQUATIONS FOR TUBE OR CAPILLARY VISCOMETER
VULCAN Series VSG-Z101 Primary Reforming
Initial Catalyst Reduction
Activating (reducing) the catalyst involves changing the nickel oxide to nickel, represented by:
NiO + H2 <==========> Ni + H2O
Natural gas is typically used as the hydrogen source. When it is, the catalyst reduction and putting the reformer on-line are accompanied in the same step.
Reactor and Catalyst Design
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 CATALYST DESIGN
4.1 Equivalent Pellet Diameter
4.2 Voidage
4.3 Pellet Density
5 REACTOR DESIGN
6 CATALYST SUPPORT
6.1 Choice of Support
TABLES
1 CATALYST SUPPORT SHAPES
2 SECONDARY REFORMER SPREADSHEET
FIGURES
1 GRAPH OF EFFECTIVENESS v THIELE MODULUS
2 VARIATION OF COSTS WITH CATALYST SIZE
3 VARIATION OF COSTS WITH CATALYST BED VOIDAGE
4 VARIATION OF COSTS WITH VESSEL DIAMETER
SMR PRE-REFORMER DESIGN
Case Study #0618416GB/H
Contents
1. SMR Pre-Reformer Design
2. Inlet Baffle Design
3. Outlet Collector
4. Hold Down Grating
5. Floating Hold Down Screen
6. Catalyst Drop Out Nozzle
7. Thermowell Detail
8. Technical Performance requirements
9. SMR Pre-Reformer Isolation
Technical Review and Commentary on Proposed Design
APPENDIX
A. Operating / Mechanical Data
B. Materials Specifications
C. Fabrication and Inspection Requirements
D. Weights
E. Nozzle Data
F. Instrument Connections
G. Manholes
DEACTIVATION OF METHANOL SYNTHESIS CATALYSTS
CONTENTS
1 INTRODUCTION
2 THERMAL SINTERING
3 CATALYST POISONING
4 REACTANT INDUCED DEACTIVATION
5 SUMMARY
TABLES
1 DEACTIVATION PROCESSES ON METHANOL SYNTHESIS CATALYSTS
2 MELTING POINT, HUTTIG AND TAMMANN TEMPERATURES OF COPPER, IRON AND NICKEL
3 SINTERING RATE CONSTANTS CALCULATED INLET AND OUTLET SIDE STREAM UNIT FOR VULCAN VSG-M101
4 COMPARISON BETWEEN CALCULATED S∞ AND DISCHARGED MEASUREMENTS ON VULCAN VSG-M101
5 EFFECT OF POSSIBLE CONTAMINANTS AND POISONS ON CU/ZNO/AL2O3 CATALYSTS FOR METHANOL SYNTHESIS
6 GUARD SCREENING TEST RESULTS ON METHANOL MICRO-REACTOR. EFFECT OF DEPOSITED METALS ON METHANOL ACTIVITY
FIGURES
1 THE HΫTTIG AND TAMMANN TEMPERATURES OF THE COMPONENTS OF A SYNTHESIS CATALYST
2 A SCHEMATIC REPRESENTATION OF TWO CATALYST SINTERING MECHANISMS
3 SIDE STREAM DATA FOR VULCAN VSG-M101. INLET TEMPERATURE 242 OC, PRESSURE 1500 PSI, GAS COMPOSITION 6% CO, 9.2% CO2, 66.9% H2, 2.5% N2 AND 15.4% CH4, SPACE VELOCITY 17,778 HR-1. MEAN OUTLET TEMPERATURE 280 OC
4 TEMPERATURE DEPENDENCE OF THE RATE OF SINTERING
5 MECHANISM OF SULFUR RETENTION
6 CORRELATION OF SULFUR CAPACITY WITH TOTAL SURFACE AREA
7 EFFECT OF DEPOSITED (NI+FE) PPM ON METHANOL SYNTHESIS CATALYST ACTIVITY
8 DISCHARGED (FE + NI) DEPOSITION LEVELS ON METHANOL SYNTHESIS PLANT SAMPLES
9 EPMA ANALYSIS OF DISCHARGED LABORATORY SAMPLE OF POISONED VULCAN VSG-M101
10 THE EFFECT OF CO2 ON SYNTHESIS CATALYST DEACTIVATION
REFERENCES
Pressure Relief Systems
BACKGROUND TO RELIEF SYSTEM DESIGN Vol.1 of 6
The Guide has been written to advise those involved in the design and engineering of pressure relief systems. It takes the user from the initial identification of potential causes of overpressure or under pressure through the process design of relief systems to the detailed mechanical design. "Hazard Studies" and quantitative hazards analysis are not described; these are seen as complementary activities. Typical users of the Guide will use some Parts in detail and others in overview.
Amine Gas Treating Unit - Best Practices - Troubleshooting Guide Gerard B. Hawkins
Amine Gas Treating Unit Best Practices - Troubleshooting Guide for H2S/CO2 Amine Systems
Contents
Process Capabilities for gas treating process
Typical Amine Treating
Typical Amine System Improvements
Primary Equipment Overview
Inlet Gas Knockout
Absorber
Three Phase Flash Tank
Lean/Rich Heat Exchanger
Regenerator
Filtration
Amine Reclaimer
Operating Difficulties Overview
Foaming
Failure to Meet Gas Specification
Solvent Losses
Corrosion
Typical Amine System Improvements
Degradation of Amines and Alkanolamines during Sour Gas Treating
APPENDIX
Best Practices - Troubleshooting Guide
VULCAN Series VSG-Z101 Primary Reforming
Initial Catalyst Reduction
Activating (reducing) the catalyst involves changing the nickel oxide to nickel, represented by:
NiO + H2 <==========> Ni + H2O
Natural gas is typically used as the hydrogen source. When it is, the catalyst reduction and putting the reformer on-line are accompanied in the same step.
Reactor and Catalyst Design
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 CATALYST DESIGN
4.1 Equivalent Pellet Diameter
4.2 Voidage
4.3 Pellet Density
5 REACTOR DESIGN
6 CATALYST SUPPORT
6.1 Choice of Support
TABLES
1 CATALYST SUPPORT SHAPES
2 SECONDARY REFORMER SPREADSHEET
FIGURES
1 GRAPH OF EFFECTIVENESS v THIELE MODULUS
2 VARIATION OF COSTS WITH CATALYST SIZE
3 VARIATION OF COSTS WITH CATALYST BED VOIDAGE
4 VARIATION OF COSTS WITH VESSEL DIAMETER
SMR PRE-REFORMER DESIGN
Case Study #0618416GB/H
Contents
1. SMR Pre-Reformer Design
2. Inlet Baffle Design
3. Outlet Collector
4. Hold Down Grating
5. Floating Hold Down Screen
6. Catalyst Drop Out Nozzle
7. Thermowell Detail
8. Technical Performance requirements
9. SMR Pre-Reformer Isolation
Technical Review and Commentary on Proposed Design
APPENDIX
A. Operating / Mechanical Data
B. Materials Specifications
C. Fabrication and Inspection Requirements
D. Weights
E. Nozzle Data
F. Instrument Connections
G. Manholes
DEACTIVATION OF METHANOL SYNTHESIS CATALYSTS
CONTENTS
1 INTRODUCTION
2 THERMAL SINTERING
3 CATALYST POISONING
4 REACTANT INDUCED DEACTIVATION
5 SUMMARY
TABLES
1 DEACTIVATION PROCESSES ON METHANOL SYNTHESIS CATALYSTS
2 MELTING POINT, HUTTIG AND TAMMANN TEMPERATURES OF COPPER, IRON AND NICKEL
3 SINTERING RATE CONSTANTS CALCULATED INLET AND OUTLET SIDE STREAM UNIT FOR VULCAN VSG-M101
4 COMPARISON BETWEEN CALCULATED S∞ AND DISCHARGED MEASUREMENTS ON VULCAN VSG-M101
5 EFFECT OF POSSIBLE CONTAMINANTS AND POISONS ON CU/ZNO/AL2O3 CATALYSTS FOR METHANOL SYNTHESIS
6 GUARD SCREENING TEST RESULTS ON METHANOL MICRO-REACTOR. EFFECT OF DEPOSITED METALS ON METHANOL ACTIVITY
FIGURES
1 THE HΫTTIG AND TAMMANN TEMPERATURES OF THE COMPONENTS OF A SYNTHESIS CATALYST
2 A SCHEMATIC REPRESENTATION OF TWO CATALYST SINTERING MECHANISMS
3 SIDE STREAM DATA FOR VULCAN VSG-M101. INLET TEMPERATURE 242 OC, PRESSURE 1500 PSI, GAS COMPOSITION 6% CO, 9.2% CO2, 66.9% H2, 2.5% N2 AND 15.4% CH4, SPACE VELOCITY 17,778 HR-1. MEAN OUTLET TEMPERATURE 280 OC
4 TEMPERATURE DEPENDENCE OF THE RATE OF SINTERING
5 MECHANISM OF SULFUR RETENTION
6 CORRELATION OF SULFUR CAPACITY WITH TOTAL SURFACE AREA
7 EFFECT OF DEPOSITED (NI+FE) PPM ON METHANOL SYNTHESIS CATALYST ACTIVITY
8 DISCHARGED (FE + NI) DEPOSITION LEVELS ON METHANOL SYNTHESIS PLANT SAMPLES
9 EPMA ANALYSIS OF DISCHARGED LABORATORY SAMPLE OF POISONED VULCAN VSG-M101
10 THE EFFECT OF CO2 ON SYNTHESIS CATALYST DEACTIVATION
REFERENCES
Pressure Relief Systems
BACKGROUND TO RELIEF SYSTEM DESIGN Vol.1 of 6
The Guide has been written to advise those involved in the design and engineering of pressure relief systems. It takes the user from the initial identification of potential causes of overpressure or under pressure through the process design of relief systems to the detailed mechanical design. "Hazard Studies" and quantitative hazards analysis are not described; these are seen as complementary activities. Typical users of the Guide will use some Parts in detail and others in overview.
Amine Gas Treating Unit - Best Practices - Troubleshooting Guide Gerard B. Hawkins
Amine Gas Treating Unit Best Practices - Troubleshooting Guide for H2S/CO2 Amine Systems
Contents
Process Capabilities for gas treating process
Typical Amine Treating
Typical Amine System Improvements
Primary Equipment Overview
Inlet Gas Knockout
Absorber
Three Phase Flash Tank
Lean/Rich Heat Exchanger
Regenerator
Filtration
Amine Reclaimer
Operating Difficulties Overview
Foaming
Failure to Meet Gas Specification
Solvent Losses
Corrosion
Typical Amine System Improvements
Degradation of Amines and Alkanolamines during Sour Gas Treating
APPENDIX
Best Practices - Troubleshooting Guide
Getting the Most Out of Your Refinery Hydrogen PlantGerard B. Hawkins
Getting the Most Out of Your Refinery Hydrogen Plant
Contents
Summary
1 Introduction
2 "On-purpose" Hydrogen Production
3 Operational Aspects
4 Uprating Options on the Steam Reformer
4.1 Steam Reforming Catalysts and Tube Metallurgy
4.2 Oxygen-blown Secondary Reformer
4.3 Pre-reforming
4.4 Post-reforming
5 Downstream Units
6 Summary of Uprating Options
7 Conclusions
DESIGN OF VENT GAS COLLECTION AND DESTRUCTION SYSTEMS Gerard B. Hawkins
DESIGN OF VENT GAS COLLECTION AND DESTRUCTION SYSTEMS
CONTENTS
1 INTRODUCTION
1.1 Purpose
1.2 Scope of this Guide
1.3 Use of the Guide
2 ENVIRONMENTAL ISSUES
2.1 Principal Concerns
2.2 Mechanisms for Ozone Formation
2.3 Photochemical Ozone Creation Potential
2.4 Health and Environmental Effects
2.5 Air Quality Standards for Ground Level Concentrations of Ozone, Targets for Reduction of VOC Discharges and Statutory Discharge Limits
3 VENTS REDUCTION PHILOSOPHY
3.1 Reduction at Source
3.2 End-of-pipe Treatment
4 METHODOLOGY FOR COLLECTION & ASSESSMENT OF PROCESS FLOW DATA
4.1 General
4.2 Identification of Vent Sources
4.3 Characterization of Vents
4.4 Quantification of Process Vent Flows
4.5 Component Flammability Data Collection
4.6 Identification of Operating Scenarios
4.7 Quantification of Flammability Characteristics for Combined Vents
4.8 Identification, Quantification and Assessment of Possibility of Air Ingress Routes
4.9 Tabulation of Data
4.10 Hazard Study and Risk Assessment
4.11 Note on Aqueous / Organic Wastes
4.12 Complexity of Systems
4.13 Summary
5 SAFE DESIGN OF VENT COLLECTION HEADER SYSTEMS
5.1 General
5.2 Process Design of Vent Headers
5.3 Liquid in Vent Headers
5.4 Materials of Construction
5.5 Static Electricity Hazard
5.6 Diversion Systems
5.7 Snuffing Systems
6 SAFE DESIGN OF THERMAL OXIDISERS
6.1 Introduction
6.2 Design Basis
6.3 Types of High Temperature Thermal Oxidizer
6.4 Refractories
6.5 Flue Gas Treatment
6.6 Control and Safety Systems
6.7 Project Program
6.8 Commissioning
6.9 Operational and Maintenance Management
APPENDICES
A GLOSSARY
B FLAMMABILITY
C EXAMPLE PROFORMA
D REFERENCES
DOCUMENTS REFERRED TO IN THIS PROCESS GUIDE
TABLE
1 PHOTOCHEMICAL OZONE CREATION POTENTIAL REFERENCED
TO ETHYLENE AS UNITY
FIGURES
1 SCHEMATIC OF TYPICAL VENT COLLECTION AND THERMAL OXIDIZER SYSTEM
2 TYPICAL KNOCK-OUT POT WITH LUTED DRAIN
3 SCHEMATIC OF DIVERSION SYSTEM
4 CONVENTIONAL VERTICAL THERMAL OXIDIZER
5 CONVENTIONAL OXIDIZER WITH INTEGRAL WATER SPARGER
6 THERMAL OXIDIZER WITH STAGED AIR INJECTION
7 DOWN-FIRED UNIT WITH WATER BATH QUENCH
8 FLAMELESS THERMAL OXIDATION UNIT
9 THERMAL OXIDIZER WITH REGENERATIVE HEAT RECOVERY
10 TYPICAL PROJECT PROGRAM
11 TYPICAL FLAMMABILITY DIAGRAM
12 EFFECT OF DILUTION WITH AIR
13 EFFECT OF DILUTION WITH AIR ON 100 Rm³ OF FLAMMABLE GAS
Catalyst Catastrophes in Syngas Production - II
Contents
Review of incidents by reactor
Primary reforming
Secondary reforming
HTS
LTS
Methanator
Reactor loading
Support media
Some general comments on alternative actions when a plant gets into abnormal operation
Pressure Relief Systems Vol 2
Causes of Relief Situations
This Volume 2 is a guide to the qualitative identification of common causes of overpressure in process equipment. It cannot be exhaustive; the process engineer and relief systems team should look for any credible situation in addition to those given in this Part which could lead to a need for pressure relief (a relief situation).
Theory of Carbon Formation in Steam Reforming
Contents
1 Introduction
2 Underpinning Theory
2.1 Conceptualization
2.2 Reforming Reactions
2.3 Carbon Formation Chemistry
2.3.1 Natural Gas
2.3.2 Carbon Formation for Naphtha Feeds
2.3.3 Carbon Gasification
2.4 Heat Transfer
3 Causes
3.1 Effects of Carbon Formation
3.2 Types of Carbon
4 What are the Effects of Carbon Formation?
4.1 Why does Carbon Formation Get Worse?
4.1.1 So what is the Next Step?
4.2 Consequences of Carbon Formation
4.3 Why does Carbon Form where it does?
4.3.1 Effect on Process Gas Temperature
4.4 Why does Carbon Formation Propagate Down the Tube?
4.4.1 Effect on Radiation on the Fluegas Side
4.5 Why does Carbon Formation propagate Up the Tube?
5 How do we Prevent Carbon Formation
5.1 The Role of Potash
5.2 Inclusion of Pre-reformer
5.3 Primary Reformer Catalyst Parameters
5.3.1 Activity
5.3.2 Heat Transfer
5.3.3 Increased Steam to Carbon Ratio
6 Steam Out
6.1 Why does increasing the Steam to Carbon Ratio Not Work?
6.2 Why does reducing the Feed Rate not help?
6.3 Fundamental Principles of Steam Outs
TABLES
1 Heat Transfer Coefficients in a Typical Reformer
2 Typical Catalyst Loading Options
FIGURES
1 Hot Bands
2 Conceptual Pellet
3 Naphtha Carbon Formation
4 Heat Transfer within an Reformer
5 Types of Carbon Formation
6 Effect of Carbon on Nickel Crystallites
7 Absorption of Heat
8 Comparison of "Base Case" v Carbon Forming Tube
9 Carbon Formation Vicious Circle
10 Temperature Profiles
11 Carbon Pinch Point
12 Carbon Formation
13 Effect on Process Gas Temperature
14 How does Carbon Propagate into an Unaffected Zone?
15 Movement of the Carbon Forming Region
16 Effect of Hot Bands on Radiative Heat Transfer
17 Effect of Potash on Carbon Formation
18 Application of a Pre-reformer
19 Effect of Activity on Carbon Formation
High Temperature Shift Catalyst Reduction ProcedureGerard B. Hawkins
High Temperature Shift Catalyst Reduction Procedure
The catalyst, as supplied, is Fe2O3. This reduces to the active form, Fe3O4, in the presence of hydrogen when process gas is admitted to the reactor.
1. The mildly exothermic reactions are:
3 Fe2O3 + H2 ========= 2 Fe3O4 + H2O
3 Fe2O3 + CO ========= 2 Fe3O4 + CO2
Pumps for Ammonium Nitrate Service
Engineering Design Guide: GBHE-EDG-MAC-1503
CONTENTS
1 SCOPE
SECTION ONE: INTEGRATION OF PUMPS INTO THE PROCESS
2 PROPERTIES OF FLUID
2.1 Decomposition
2.2 Combustion
2.3 Detonation
2.4 Deliquescence
2.5 Density
2.6 Viscosity
2.7 Vapor Pressure
2.8 Freezing Point
2.9 Specific Heat
2.10 Surface Tension
2.11 Thermal Conductivity
3 CALCULATION OF DUTY
3.1 Centrifugal Pumps
4 CHOICE OF PUMP TYPE
4.1 Centrifugal Pumps
4.2 Rotary Pumps
4.3 Reciprocating Pumps
5 LINE DIAGRAMS
5.1 Centrifugal Pumps with Mechanical Seals
5.2 Vertical Suspended Cantilever Shaft Pumps for
Melt Service
5.3 Horizontal Self-Priming Pumps
5.4 Reciprocating Pumps
5.5 Seal Water Supply System
6 LAYOUT
6.1 Vertical Cantilever Shaft Pumps - Tank Proportions
SECTION TWO: CONSTRUCTION FEATURES OF PUMPS
7 SEALS FOR CENTRIFUGAL PUMPS
7.1 Below 30% AN
7.2 30-45% AN
7.3 45-90% AN
7.4 Above 90% AN
8 PACKED GLANDS FOR RECIPROCATING PUMPS
8.1 Below 90% AN
9 SEAL WATER SUPPLY SYSTEMS
10 CONSTRUCTION FEATURES OF CENTRIFUGAL PUMPS
10.1 Casing
10.2 Rotor
10.3 Bearing Lubrication
10.4 Coupling
10.5 Baseplate
11 CONSTRUCTION FEATURES OF VERTICAL CANTILEVER SHAFT IMMERSED PUMPS
11.1 Motor
11.2 Insulation and Jacketing
11.3 Rotor
11.4 Bearing Lubrication
11.5 Preservation
12 CONSTRUCTION FEATURES OF RECIPROCATING PLUNGER PUMPS
12.1 Speed Limits
12.2 Casing and Gearbox
12.3 Couplings
13 MATERIALS OF CONSTRUCTION
13.1 Recommended Materials
13.2 Forbidden Materials
APPENDIX A: BEARING LUBRICANTS
FIGURES
2.5.1 DENSITY OF AMMONIUM NITRATE SOLUTIONS
2.5.2 DENSITY OF AMMONIUM NITRATE SOLUTIONS
2.6 KINEMATIC VISCOSITY OF AMMONIUM NITRATE SOLUTIONS
2.7.1 WATER VAPOR PRESSURE ABOVE AMMONIUM NITRATE SOLUTIONS
2.7.2 AMMONIA VAPOR PRESSURE FOR AM!AMMONIUM NITRATE MELT
2.8 FREEZING POINT OF AMMONIUM NITRATE SOLUTIONS
2.9 SPECIFIC HEAT OF AMMONIUM NITRATE SOLUTIONS
4 SELECTION OF PUMP TYPE
5. 1 RECOMMENDED LINE DIAGRAM CENTRIFUGAL PUMPS WITH MECHANICAL SEALS
5.2 RECOMMENDED LINE DIAGRAM: VERTICAL SUSPENDED CANTILEVER PUMPS
5.3 RECOMMENDED LINE DIAGRAM: HORIZONTAL SELF
PRIMING PUMPS
5.4 RECOMMENDED LINE DIAGRAM: RECIPROCATING PLUNGER PUMPS
5.5 RECOMMENDED LINE DIAGRAM SEAL: WATER PUMPS AND INJECTION PUMP SYSTEMS
7.2 TYPICAL ARRANGEMENT OF SEAL WITH NO INJECTION FLUSH
7.3 TYPICAL ARRANGEMENT OF CRANE TYPE 52B WITH 'J' SEAT INCORPORATING TETRALIPS INBOARD AND OUTBOARD
7.4 TYPICAL ARRANGEMENT OF LABYRINTH SEAL FOR VERTICAL SUSPENDED CANTILEVER SHAFT PUMPS
8.1 TYPICAL ARRANGEMENT OF SOFT PACKED GLAND FOR RECIPROCATING PLUNGER PUMPS FOR DELIVERY PRESSURES UP TO 10 BAR G.
12 TEMPERATURES ATTAINED ON DISSOLUTION OF ANHYDROUS CAUSTIC SODA
TABLES
13.1 MATERIALS OF CONSTRUCTION CENTRIFUGAL PUMPS
13.2 MATERIALS OF CONSTRUCTION VERTICAL CANTILEVER
SHAFT IMMERSED PUMPS
13.3 MATERIALS OF CONSTRUCTION RECIPROCATING PLUNGER PUMPS
Design and Simulation of Continuous Distillation ColumnsGerard B. Hawkins
Design and Simulation of Continuous Distillation Columns
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 FRACTIONAL DISTILLATION
5 ROUGH METHOD OF COLUMN DESIGN
5.1 Sharp Separations
5.2 Sloppy Separations
6 DETAIL DESIGN USING THE CHEMCAD DISTILLATION PROGRAM
6.1 Sharp Separations
6.2 Sloppy Separations
7 COMPLEX COLUMNS
7.1 Multiple Feeds
7.2 Sidestream Take-Offs
8 DESIGN USING A LABORATORY COLUMN
SIMULATION
9 DESIGN USING ACTUAL PLANT DATA
9.1 Uprating or Debottlenecking Exercises
10 REFERENCES
APPENDICES
A WORKED EXAMPLE
B SLOPPY SEPARATIONS
C SIMULATION USING PLANT DATA : CASE HISTORIES
TABLES
Tools for Reactor Modeling:
THE ELEMENT POTENTIAL METHOD FOR CHEMICAL EQUILIBRIUM ANALYSIS: STANJAN
CONTENTS
1 SCOPE
2 SUMMARY
3 INTRODUCTION
4 EXAMPLES
4.1 CARBON-RICH C-0 SYSTEM
4.2 EXAMPLE WITH TWO COMPLEX PHASES
4.3 GAS TURBINE ENGINE EXAMPLE
4.4 OTHER APPLICATIONS
APPENDIX
FIGURES
5.1 EXAMPLE RUN LOG FOR CARBON-RICH C-O SYSTEM
5.2 OUTPUT FOR EXAMPLE WITH TWO COMPLEX PHASES
5.3 FIRST STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE ENTHALPY OF THE REACTANTS
5.4 SECOND STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE ADIABATIC FLAME TEMPERATURE
5.5 THIRD STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE NOZZLE EXIT STATE
AVAILABILITY AND IMPLEMENTATION OF STANJAN
REFERENCES
Most modern ammonia processes are based on steam-reforming of natural gas or naphtha.
The 3 main technology suppliers are Uhde (Uhde/JM Partnership), Topsoe & KBR.
The process steps are very similar in all cases.
Other suppliers are Linde (LAC) & Ammonia Casale.
CONTENTS
1 SCOPE
2 PROPERTIES OF FLUID
2.1 General Properties of Sodium Hydroxide
2.2 Physical Properties of Sodium Hydroxide and its Solutions
2.3 Chemical Properties and uses of Sodium Hydroxide
2.4 Physiological effects of Sodium Hydroxide
2.5 Specifications of Commercial Caustic Soda Grades
3 CHOICE OF PUMP TYPE
3.1 Pump Duty
3.2 Pump Type
4 RECOMMENDED LINE DIAGRAMS
5 RECOMMENDED LAYOUT
6 CONSTRUCTION FEATURES
7 MATERIALS OF CONSTRUCTION
7.1 Nickel and Nickel Alloys
7.2 Austenitic Stainless Steel
7.3 Aluminium, Aluminium Alloys, etc.
7.4 Non-Metallic Materials
TABLES
1 PHYSICAL PROPERTIES (Solid Form)
2 PHYSICAL PROPERTIES (Solution Form)
3 CAUSTIC SODA GRADES
FIGURES
1.1 LINE DIAGRAM - HORIZONTAL GLANDED, GLANDLESS AND VERTICAL IN-LINE PUMPS
1.2 LINE DIAGRAM - VERTICAL SPINDLE CANTILEVER PUMPS
1.3 LINE DIAGRAM - SELF PRIMING PUMPS
1.4 LINE DIAGRAM - RECIPROCATING PLUNGER METERING PUMPS
1.5 LINE DIAGRAM - POSITIVE DISPLACEMENT DIAPHRAGM METERING PUMPS
1.6 WATER FLUSHING ARRANGEMENT FOR DOUBLE MECHANICAL SEAL
1.7 WATER FLUSH (QUENCH) ARRANGEMENT FOR SINGLE HARD FACED (CARBIDE) SEAL AND BACK-UP LIP SEAL
2 PHASE DIAGRAM OF NaOH-H2O
3 VISCOSITY OF AQUEOUS CAUSTIC SODA SOLUTIONS
4 VAPOR PRESSURE OF AQUEOUS CAUSTIC SODA SOLUTIONS
5 ENTHALPY CONCENTRATION FOR AQUEOUS CAUSTIC SODA SOLUTIONS
6 SPECIFIC GRAVITY FOR AQUEOUS CAUSTIC SODA SOLUTIONS
7 DILUTION OF CAUSTIC SODA LIQUOR
8 THERMAL CONDUCTIVITY OF AQUEOUS CAUSTIC SODA SOLUTIONS
9 SPECIFIC HEAT OF CAUSTIC SODA SOLUTIONS
10 BOILING POINTS OF STRONG CAUSTIC SODA SOLUTIONS AT REDUCED PRESSURE
11 COMMENCEMENT OF FREEZING OF CAUSTIC SODA SOLUTIONS (0 - 52% W/W)
12 TEMPERATURES ATTAINED ON DISSOLUTION OF ANHYDROUS CAUSTIC SODA
13 HEAT OF SOLUTION FOR ANHYDROUS CAUSTIC SODA
14 SOLUBILITY OF SODIUM CHLORIDE IN CAUSTIC SODA SOLUTIONS
15 DENSITY - CONCENTRATION TABLES FOR CAUSTIC SODA SOLUTIONS AT 600 F (15.5 0 C)
16 MATERIAL SELECTION CHART FOR CAUSTIC SODA HANDLING
Solid Catalyzed Reactions
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 GENERAL BACKGROUND
4.1 General Considerations
5 SOLID CATALYZED GAS REACTIONS
5.1 Reaction Kinetics
5.2 Tests for Transport Limitations
5.3 Building a Reaction Kinetic Equation
6 INTRAPARTICLE
6.1 Types of Pore System
6.2 The Catalyst Effectiveness Factor
6.3 The Measurement of Effective Diffusivity
7 ENHANCEMENT OF INTRAPARTICLE
8 NOMENCLATURE
8.1 Dimensionless Parameters
8.2 Greek Letters
8.3 Subscripts
9 BIBLIOGRAPHY
9.1 Further Reading
APPENDICES
A LANGMUIR - HINSHELWOOD KINETICS
FIGURES
1 EFFECTIVE RATE CONSTANT
2 ITERATIVE APPROACH TO REACTOR MODEL
DEVELOPMENT
3 COMMON LABORATORY MICROREACTORS (FLOW TYPE)
4 THE BERTY REACTOR
5 STEPS IN BUILDING A REACTION RATE EQUATION
6 A CENTRAL-COMPOSITE DESIGN FOR TWO FACTORS
7 FIRST ORDER ISOTHERMAL IRREVERSIBLE
REACTION WITHIN A CATALYST SPHERE
8 INTEGRAL YIELD vs CONVERSION SHOWING EFFECT OF PELLET DIFFUSION
9 PREDICTED AND EXPERIMENTAL EFFECTIVENESS FACTORS
10 STRUCTURAL PERMEABILITY vs PRESSURE PARAMETER Z FOR BI-MODAL SUPPORTS
11 EFFECTIVENESS FACTOR vs THIELE MODULUS AND INTRAPARTICLE PECLET NUMBER
12 RELATIVE INCREASE IN CATALYST PERFORMANCE
How to Use the GBHE Mixing Guides
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 THE MIXING GUIDES
4.1 Mixing Guides
4.2 GBHE Mixing and Agitation Manual
5 DEVICE SELECTION
6 MIXING QUESTIONNAIRE
6.1 What is being mixed?
6.2 Why is it being mixed?
6.3 How is it to be mixed?
6.4 Is Heat Transfer Important?
6.5 Is Mixing Time Important?
6.6 Is Inventory Important?
6.7 Is Subsequent Phase Separation Important?
6.8 What Quantities?
6.9 What are the Selection Criteria?
6.10 What Data are required?
7 BASICS
7.1 Bulk Movement
7.2 Shear and Elongation
7.3 Turbulent Diffusion
7.4 Molecular Diffusion
7.5 Mixing Mechanisms
APPENDICES
A ROTATING MIXING DEVICES
B MIXING DEVICES WITHOUT MOVING PARTS
Getting the Most Out of Your Refinery Hydrogen PlantGerard B. Hawkins
Getting the Most Out of Your Refinery Hydrogen Plant
Contents
Summary
1 Introduction
2 "On-purpose" Hydrogen Production
3 Operational Aspects
4 Uprating Options on the Steam Reformer
4.1 Steam Reforming Catalysts and Tube Metallurgy
4.2 Oxygen-blown Secondary Reformer
4.3 Pre-reforming
4.4 Post-reforming
5 Downstream Units
6 Summary of Uprating Options
7 Conclusions
DESIGN OF VENT GAS COLLECTION AND DESTRUCTION SYSTEMS Gerard B. Hawkins
DESIGN OF VENT GAS COLLECTION AND DESTRUCTION SYSTEMS
CONTENTS
1 INTRODUCTION
1.1 Purpose
1.2 Scope of this Guide
1.3 Use of the Guide
2 ENVIRONMENTAL ISSUES
2.1 Principal Concerns
2.2 Mechanisms for Ozone Formation
2.3 Photochemical Ozone Creation Potential
2.4 Health and Environmental Effects
2.5 Air Quality Standards for Ground Level Concentrations of Ozone, Targets for Reduction of VOC Discharges and Statutory Discharge Limits
3 VENTS REDUCTION PHILOSOPHY
3.1 Reduction at Source
3.2 End-of-pipe Treatment
4 METHODOLOGY FOR COLLECTION & ASSESSMENT OF PROCESS FLOW DATA
4.1 General
4.2 Identification of Vent Sources
4.3 Characterization of Vents
4.4 Quantification of Process Vent Flows
4.5 Component Flammability Data Collection
4.6 Identification of Operating Scenarios
4.7 Quantification of Flammability Characteristics for Combined Vents
4.8 Identification, Quantification and Assessment of Possibility of Air Ingress Routes
4.9 Tabulation of Data
4.10 Hazard Study and Risk Assessment
4.11 Note on Aqueous / Organic Wastes
4.12 Complexity of Systems
4.13 Summary
5 SAFE DESIGN OF VENT COLLECTION HEADER SYSTEMS
5.1 General
5.2 Process Design of Vent Headers
5.3 Liquid in Vent Headers
5.4 Materials of Construction
5.5 Static Electricity Hazard
5.6 Diversion Systems
5.7 Snuffing Systems
6 SAFE DESIGN OF THERMAL OXIDISERS
6.1 Introduction
6.2 Design Basis
6.3 Types of High Temperature Thermal Oxidizer
6.4 Refractories
6.5 Flue Gas Treatment
6.6 Control and Safety Systems
6.7 Project Program
6.8 Commissioning
6.9 Operational and Maintenance Management
APPENDICES
A GLOSSARY
B FLAMMABILITY
C EXAMPLE PROFORMA
D REFERENCES
DOCUMENTS REFERRED TO IN THIS PROCESS GUIDE
TABLE
1 PHOTOCHEMICAL OZONE CREATION POTENTIAL REFERENCED
TO ETHYLENE AS UNITY
FIGURES
1 SCHEMATIC OF TYPICAL VENT COLLECTION AND THERMAL OXIDIZER SYSTEM
2 TYPICAL KNOCK-OUT POT WITH LUTED DRAIN
3 SCHEMATIC OF DIVERSION SYSTEM
4 CONVENTIONAL VERTICAL THERMAL OXIDIZER
5 CONVENTIONAL OXIDIZER WITH INTEGRAL WATER SPARGER
6 THERMAL OXIDIZER WITH STAGED AIR INJECTION
7 DOWN-FIRED UNIT WITH WATER BATH QUENCH
8 FLAMELESS THERMAL OXIDATION UNIT
9 THERMAL OXIDIZER WITH REGENERATIVE HEAT RECOVERY
10 TYPICAL PROJECT PROGRAM
11 TYPICAL FLAMMABILITY DIAGRAM
12 EFFECT OF DILUTION WITH AIR
13 EFFECT OF DILUTION WITH AIR ON 100 Rm³ OF FLAMMABLE GAS
Catalyst Catastrophes in Syngas Production - II
Contents
Review of incidents by reactor
Primary reforming
Secondary reforming
HTS
LTS
Methanator
Reactor loading
Support media
Some general comments on alternative actions when a plant gets into abnormal operation
Pressure Relief Systems Vol 2
Causes of Relief Situations
This Volume 2 is a guide to the qualitative identification of common causes of overpressure in process equipment. It cannot be exhaustive; the process engineer and relief systems team should look for any credible situation in addition to those given in this Part which could lead to a need for pressure relief (a relief situation).
Theory of Carbon Formation in Steam Reforming
Contents
1 Introduction
2 Underpinning Theory
2.1 Conceptualization
2.2 Reforming Reactions
2.3 Carbon Formation Chemistry
2.3.1 Natural Gas
2.3.2 Carbon Formation for Naphtha Feeds
2.3.3 Carbon Gasification
2.4 Heat Transfer
3 Causes
3.1 Effects of Carbon Formation
3.2 Types of Carbon
4 What are the Effects of Carbon Formation?
4.1 Why does Carbon Formation Get Worse?
4.1.1 So what is the Next Step?
4.2 Consequences of Carbon Formation
4.3 Why does Carbon Form where it does?
4.3.1 Effect on Process Gas Temperature
4.4 Why does Carbon Formation Propagate Down the Tube?
4.4.1 Effect on Radiation on the Fluegas Side
4.5 Why does Carbon Formation propagate Up the Tube?
5 How do we Prevent Carbon Formation
5.1 The Role of Potash
5.2 Inclusion of Pre-reformer
5.3 Primary Reformer Catalyst Parameters
5.3.1 Activity
5.3.2 Heat Transfer
5.3.3 Increased Steam to Carbon Ratio
6 Steam Out
6.1 Why does increasing the Steam to Carbon Ratio Not Work?
6.2 Why does reducing the Feed Rate not help?
6.3 Fundamental Principles of Steam Outs
TABLES
1 Heat Transfer Coefficients in a Typical Reformer
2 Typical Catalyst Loading Options
FIGURES
1 Hot Bands
2 Conceptual Pellet
3 Naphtha Carbon Formation
4 Heat Transfer within an Reformer
5 Types of Carbon Formation
6 Effect of Carbon on Nickel Crystallites
7 Absorption of Heat
8 Comparison of "Base Case" v Carbon Forming Tube
9 Carbon Formation Vicious Circle
10 Temperature Profiles
11 Carbon Pinch Point
12 Carbon Formation
13 Effect on Process Gas Temperature
14 How does Carbon Propagate into an Unaffected Zone?
15 Movement of the Carbon Forming Region
16 Effect of Hot Bands on Radiative Heat Transfer
17 Effect of Potash on Carbon Formation
18 Application of a Pre-reformer
19 Effect of Activity on Carbon Formation
High Temperature Shift Catalyst Reduction ProcedureGerard B. Hawkins
High Temperature Shift Catalyst Reduction Procedure
The catalyst, as supplied, is Fe2O3. This reduces to the active form, Fe3O4, in the presence of hydrogen when process gas is admitted to the reactor.
1. The mildly exothermic reactions are:
3 Fe2O3 + H2 ========= 2 Fe3O4 + H2O
3 Fe2O3 + CO ========= 2 Fe3O4 + CO2
Pumps for Ammonium Nitrate Service
Engineering Design Guide: GBHE-EDG-MAC-1503
CONTENTS
1 SCOPE
SECTION ONE: INTEGRATION OF PUMPS INTO THE PROCESS
2 PROPERTIES OF FLUID
2.1 Decomposition
2.2 Combustion
2.3 Detonation
2.4 Deliquescence
2.5 Density
2.6 Viscosity
2.7 Vapor Pressure
2.8 Freezing Point
2.9 Specific Heat
2.10 Surface Tension
2.11 Thermal Conductivity
3 CALCULATION OF DUTY
3.1 Centrifugal Pumps
4 CHOICE OF PUMP TYPE
4.1 Centrifugal Pumps
4.2 Rotary Pumps
4.3 Reciprocating Pumps
5 LINE DIAGRAMS
5.1 Centrifugal Pumps with Mechanical Seals
5.2 Vertical Suspended Cantilever Shaft Pumps for
Melt Service
5.3 Horizontal Self-Priming Pumps
5.4 Reciprocating Pumps
5.5 Seal Water Supply System
6 LAYOUT
6.1 Vertical Cantilever Shaft Pumps - Tank Proportions
SECTION TWO: CONSTRUCTION FEATURES OF PUMPS
7 SEALS FOR CENTRIFUGAL PUMPS
7.1 Below 30% AN
7.2 30-45% AN
7.3 45-90% AN
7.4 Above 90% AN
8 PACKED GLANDS FOR RECIPROCATING PUMPS
8.1 Below 90% AN
9 SEAL WATER SUPPLY SYSTEMS
10 CONSTRUCTION FEATURES OF CENTRIFUGAL PUMPS
10.1 Casing
10.2 Rotor
10.3 Bearing Lubrication
10.4 Coupling
10.5 Baseplate
11 CONSTRUCTION FEATURES OF VERTICAL CANTILEVER SHAFT IMMERSED PUMPS
11.1 Motor
11.2 Insulation and Jacketing
11.3 Rotor
11.4 Bearing Lubrication
11.5 Preservation
12 CONSTRUCTION FEATURES OF RECIPROCATING PLUNGER PUMPS
12.1 Speed Limits
12.2 Casing and Gearbox
12.3 Couplings
13 MATERIALS OF CONSTRUCTION
13.1 Recommended Materials
13.2 Forbidden Materials
APPENDIX A: BEARING LUBRICANTS
FIGURES
2.5.1 DENSITY OF AMMONIUM NITRATE SOLUTIONS
2.5.2 DENSITY OF AMMONIUM NITRATE SOLUTIONS
2.6 KINEMATIC VISCOSITY OF AMMONIUM NITRATE SOLUTIONS
2.7.1 WATER VAPOR PRESSURE ABOVE AMMONIUM NITRATE SOLUTIONS
2.7.2 AMMONIA VAPOR PRESSURE FOR AM!AMMONIUM NITRATE MELT
2.8 FREEZING POINT OF AMMONIUM NITRATE SOLUTIONS
2.9 SPECIFIC HEAT OF AMMONIUM NITRATE SOLUTIONS
4 SELECTION OF PUMP TYPE
5. 1 RECOMMENDED LINE DIAGRAM CENTRIFUGAL PUMPS WITH MECHANICAL SEALS
5.2 RECOMMENDED LINE DIAGRAM: VERTICAL SUSPENDED CANTILEVER PUMPS
5.3 RECOMMENDED LINE DIAGRAM: HORIZONTAL SELF
PRIMING PUMPS
5.4 RECOMMENDED LINE DIAGRAM: RECIPROCATING PLUNGER PUMPS
5.5 RECOMMENDED LINE DIAGRAM SEAL: WATER PUMPS AND INJECTION PUMP SYSTEMS
7.2 TYPICAL ARRANGEMENT OF SEAL WITH NO INJECTION FLUSH
7.3 TYPICAL ARRANGEMENT OF CRANE TYPE 52B WITH 'J' SEAT INCORPORATING TETRALIPS INBOARD AND OUTBOARD
7.4 TYPICAL ARRANGEMENT OF LABYRINTH SEAL FOR VERTICAL SUSPENDED CANTILEVER SHAFT PUMPS
8.1 TYPICAL ARRANGEMENT OF SOFT PACKED GLAND FOR RECIPROCATING PLUNGER PUMPS FOR DELIVERY PRESSURES UP TO 10 BAR G.
12 TEMPERATURES ATTAINED ON DISSOLUTION OF ANHYDROUS CAUSTIC SODA
TABLES
13.1 MATERIALS OF CONSTRUCTION CENTRIFUGAL PUMPS
13.2 MATERIALS OF CONSTRUCTION VERTICAL CANTILEVER
SHAFT IMMERSED PUMPS
13.3 MATERIALS OF CONSTRUCTION RECIPROCATING PLUNGER PUMPS
Design and Simulation of Continuous Distillation ColumnsGerard B. Hawkins
Design and Simulation of Continuous Distillation Columns
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 FRACTIONAL DISTILLATION
5 ROUGH METHOD OF COLUMN DESIGN
5.1 Sharp Separations
5.2 Sloppy Separations
6 DETAIL DESIGN USING THE CHEMCAD DISTILLATION PROGRAM
6.1 Sharp Separations
6.2 Sloppy Separations
7 COMPLEX COLUMNS
7.1 Multiple Feeds
7.2 Sidestream Take-Offs
8 DESIGN USING A LABORATORY COLUMN
SIMULATION
9 DESIGN USING ACTUAL PLANT DATA
9.1 Uprating or Debottlenecking Exercises
10 REFERENCES
APPENDICES
A WORKED EXAMPLE
B SLOPPY SEPARATIONS
C SIMULATION USING PLANT DATA : CASE HISTORIES
TABLES
Tools for Reactor Modeling:
THE ELEMENT POTENTIAL METHOD FOR CHEMICAL EQUILIBRIUM ANALYSIS: STANJAN
CONTENTS
1 SCOPE
2 SUMMARY
3 INTRODUCTION
4 EXAMPLES
4.1 CARBON-RICH C-0 SYSTEM
4.2 EXAMPLE WITH TWO COMPLEX PHASES
4.3 GAS TURBINE ENGINE EXAMPLE
4.4 OTHER APPLICATIONS
APPENDIX
FIGURES
5.1 EXAMPLE RUN LOG FOR CARBON-RICH C-O SYSTEM
5.2 OUTPUT FOR EXAMPLE WITH TWO COMPLEX PHASES
5.3 FIRST STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE ENTHALPY OF THE REACTANTS
5.4 SECOND STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE ADIABATIC FLAME TEMPERATURE
5.5 THIRD STEP IN THE TURBINE EXAMPLE: CALCULATION OF THE NOZZLE EXIT STATE
AVAILABILITY AND IMPLEMENTATION OF STANJAN
REFERENCES
Most modern ammonia processes are based on steam-reforming of natural gas or naphtha.
The 3 main technology suppliers are Uhde (Uhde/JM Partnership), Topsoe & KBR.
The process steps are very similar in all cases.
Other suppliers are Linde (LAC) & Ammonia Casale.
CONTENTS
1 SCOPE
2 PROPERTIES OF FLUID
2.1 General Properties of Sodium Hydroxide
2.2 Physical Properties of Sodium Hydroxide and its Solutions
2.3 Chemical Properties and uses of Sodium Hydroxide
2.4 Physiological effects of Sodium Hydroxide
2.5 Specifications of Commercial Caustic Soda Grades
3 CHOICE OF PUMP TYPE
3.1 Pump Duty
3.2 Pump Type
4 RECOMMENDED LINE DIAGRAMS
5 RECOMMENDED LAYOUT
6 CONSTRUCTION FEATURES
7 MATERIALS OF CONSTRUCTION
7.1 Nickel and Nickel Alloys
7.2 Austenitic Stainless Steel
7.3 Aluminium, Aluminium Alloys, etc.
7.4 Non-Metallic Materials
TABLES
1 PHYSICAL PROPERTIES (Solid Form)
2 PHYSICAL PROPERTIES (Solution Form)
3 CAUSTIC SODA GRADES
FIGURES
1.1 LINE DIAGRAM - HORIZONTAL GLANDED, GLANDLESS AND VERTICAL IN-LINE PUMPS
1.2 LINE DIAGRAM - VERTICAL SPINDLE CANTILEVER PUMPS
1.3 LINE DIAGRAM - SELF PRIMING PUMPS
1.4 LINE DIAGRAM - RECIPROCATING PLUNGER METERING PUMPS
1.5 LINE DIAGRAM - POSITIVE DISPLACEMENT DIAPHRAGM METERING PUMPS
1.6 WATER FLUSHING ARRANGEMENT FOR DOUBLE MECHANICAL SEAL
1.7 WATER FLUSH (QUENCH) ARRANGEMENT FOR SINGLE HARD FACED (CARBIDE) SEAL AND BACK-UP LIP SEAL
2 PHASE DIAGRAM OF NaOH-H2O
3 VISCOSITY OF AQUEOUS CAUSTIC SODA SOLUTIONS
4 VAPOR PRESSURE OF AQUEOUS CAUSTIC SODA SOLUTIONS
5 ENTHALPY CONCENTRATION FOR AQUEOUS CAUSTIC SODA SOLUTIONS
6 SPECIFIC GRAVITY FOR AQUEOUS CAUSTIC SODA SOLUTIONS
7 DILUTION OF CAUSTIC SODA LIQUOR
8 THERMAL CONDUCTIVITY OF AQUEOUS CAUSTIC SODA SOLUTIONS
9 SPECIFIC HEAT OF CAUSTIC SODA SOLUTIONS
10 BOILING POINTS OF STRONG CAUSTIC SODA SOLUTIONS AT REDUCED PRESSURE
11 COMMENCEMENT OF FREEZING OF CAUSTIC SODA SOLUTIONS (0 - 52% W/W)
12 TEMPERATURES ATTAINED ON DISSOLUTION OF ANHYDROUS CAUSTIC SODA
13 HEAT OF SOLUTION FOR ANHYDROUS CAUSTIC SODA
14 SOLUBILITY OF SODIUM CHLORIDE IN CAUSTIC SODA SOLUTIONS
15 DENSITY - CONCENTRATION TABLES FOR CAUSTIC SODA SOLUTIONS AT 600 F (15.5 0 C)
16 MATERIAL SELECTION CHART FOR CAUSTIC SODA HANDLING
Solid Catalyzed Reactions
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 GENERAL BACKGROUND
4.1 General Considerations
5 SOLID CATALYZED GAS REACTIONS
5.1 Reaction Kinetics
5.2 Tests for Transport Limitations
5.3 Building a Reaction Kinetic Equation
6 INTRAPARTICLE
6.1 Types of Pore System
6.2 The Catalyst Effectiveness Factor
6.3 The Measurement of Effective Diffusivity
7 ENHANCEMENT OF INTRAPARTICLE
8 NOMENCLATURE
8.1 Dimensionless Parameters
8.2 Greek Letters
8.3 Subscripts
9 BIBLIOGRAPHY
9.1 Further Reading
APPENDICES
A LANGMUIR - HINSHELWOOD KINETICS
FIGURES
1 EFFECTIVE RATE CONSTANT
2 ITERATIVE APPROACH TO REACTOR MODEL
DEVELOPMENT
3 COMMON LABORATORY MICROREACTORS (FLOW TYPE)
4 THE BERTY REACTOR
5 STEPS IN BUILDING A REACTION RATE EQUATION
6 A CENTRAL-COMPOSITE DESIGN FOR TWO FACTORS
7 FIRST ORDER ISOTHERMAL IRREVERSIBLE
REACTION WITHIN A CATALYST SPHERE
8 INTEGRAL YIELD vs CONVERSION SHOWING EFFECT OF PELLET DIFFUSION
9 PREDICTED AND EXPERIMENTAL EFFECTIVENESS FACTORS
10 STRUCTURAL PERMEABILITY vs PRESSURE PARAMETER Z FOR BI-MODAL SUPPORTS
11 EFFECTIVENESS FACTOR vs THIELE MODULUS AND INTRAPARTICLE PECLET NUMBER
12 RELATIVE INCREASE IN CATALYST PERFORMANCE
How to Use the GBHE Mixing Guides
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 THE MIXING GUIDES
4.1 Mixing Guides
4.2 GBHE Mixing and Agitation Manual
5 DEVICE SELECTION
6 MIXING QUESTIONNAIRE
6.1 What is being mixed?
6.2 Why is it being mixed?
6.3 How is it to be mixed?
6.4 Is Heat Transfer Important?
6.5 Is Mixing Time Important?
6.6 Is Inventory Important?
6.7 Is Subsequent Phase Separation Important?
6.8 What Quantities?
6.9 What are the Selection Criteria?
6.10 What Data are required?
7 BASICS
7.1 Bulk Movement
7.2 Shear and Elongation
7.3 Turbulent Diffusion
7.4 Molecular Diffusion
7.5 Mixing Mechanisms
APPENDICES
A ROTATING MIXING DEVICES
B MIXING DEVICES WITHOUT MOVING PARTS
Estimation of Pressure Drop in Pipe Systems
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
3.1 units
4 SOURCES OF DATA
5 BASIC CONCEPTS
5.1 Equation for Pressure Change in a Flowing
Fluid
5.2 Static and Stagnation Pressures
5.3 Sonic Flow
6 INCOMPRESSIBLE FLOW IN PIPES OF CONSTANT
CROSS-SECTION
6.1 Straight Circular Pipes
6.2 Ducts of Non-circular Cross-section
6.3 Coils
6.4 General Equation for Incompressible Flow
in Pipes of Constant Cross-section
7 COMPRESSIBLE FLOW IN PIPES OF CONSTANT
CROSS-SECTION
7.1 Isothermal Flow
7.2 Adiabatic Flow
7.3 Estimation of Pressure Drop for Adiabatic
Flow in Pipes of Constant Cross-section
7.4 Ratio of Isothermal to Adiabatic Pressure Drop
8 FLOW IN PIPE FITTINGS
8.1 Incompressible Flow
8.2 Compressible Flow
9 FLOW IN BENDS
9.1 Incompressible Flow in Bends
9.2 Compressible Flow in Bends
10 CHANGES IN CROSS-SECTIONAL AREA
9.1 Incompressible Flow
9.2 Compressible Flow
11 ORIFICES, NOZZLES AND VENTURIS
11.1 Incompressible Flow through an Orifice
11.2 Compressible Flow through an Orifice or Nozzle
11.3 Venturi Choke Tubes
12 VALVES
12.1 General
12.2 Incompressible Flow in Valves
12.2 Compressible Flow in Valves
13 COMBINING AND DIVIDING FLOW
9.1 Incompressible Flow
9.2 Compressible Flow
14 COMPUTER PROGRAMS FOR FLUID FLOW
15 NOMENCLATURE
16 REFERENCES
APPENDICES
A BASIC THERMODYNAMICS
B COMPRESSIBLE FLOW THROUGH ORIFICES
C THE ‘TWO-K’ METHOD FOR FITTING PRESSURE LOSS
Pipeline Design for Isothermal, Laminar Flow of Non-Newtonian FluidsGerard B. Hawkins
Pipeline Design for Isothermal, Laminar Flow of Non-Newtonian Fluids
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 RHEOLOGICAL BEHAVIOR OF PURELY VISCOUS
NON-NEWTONIAN FLUIDS
4.1 Experimental Characterization
4.2 Rheological Models
5 PRESSURE DROP-FLOW RATE RELATIONSHIPS
BASED DIRECTLY ON EXPERIMENTAL DATA
5.1 Use of Shear Stress – Shear Rate Data
5.2 Tubular Viscometer Data
6 PRESSURE DROP – FLOW RATE RELATIONSHIPS BASED ON RHEOLOGICAL MODELS
7 LOSSES IN PIPE FITTINGS
7.1 Entrances Losses
7.2 Expansion Effects
7.3 Contraction Losses
7.4 Valves
7.5 Bends
8 EFFECT OF WALL SLIP
9 VELOCITY PROFILES
9.1 Velocity Profile from Experimental Flow-Curve
9.2 Velocity Profile from Rheological Model
9.3 Residence Time Distribution
10 CHECKS ON THE VALIDITY OF THE
DESIGN PROCEDURES
10.1 Rheological Behavior
10.2 Validity of Experimental Data
10.2 Check on Laminar Flow
11 NOMENCLATURE
12 REFERENCES
FIGURES
1 FLOW CURVES FOR PURELY VISCOUS FLUIDS
2 PLOTS OF D∆P/4L VERSUS 32Q/ɳD3 FOR PURELY VISCOUS FLUIDS
3 LOG-LOG PLOT OF t VERSUS ý
4 FLOW CURVE FOR A BINGHAM PLASTIC
5 LOG-LOG PLOT FOR A GENERALIZED BINGHAM
PLASTIC
6 CORRELATION OF ENTRANCE LOSS
7 CORRELATION OF EXPANSION LOSS
8 EFFECT OF “WALL SLIP” ON VELOCITY PROFILE
9 D∆P/4L VERSUS Q/ɳR3 WITH WALL SLIP
10 EVALUATION OFUs WITH Ʈw
11 VARIATION OF Us WITH Ʈw
12 PLOT OF D∆P/4L VERSUS 8 (ū- Us)/D FOR
CONDITIONS OF WALL SLIP
13 CUMULATIVE RESIDENCE TIME DISTRIBUTION
TO POWER LAW FLUIDS
14 EFFECTS OF TUBE LENGTH AND DIAMETER ON
RELATIONSHIP BETWEEN D∆P/4L AND 32Q/ɳD3
Mixing of Miscible Liquids
Mixing of Miscible Liquids
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 SELECTION OF EQUIPMENT
4.1 Mechanically Agitated Vessels
4.2 Jet Mixed Vessels
4.3 Tubular ('Flow') Mixers
5 AGITATED VESSELS
5.1 Mixing Time for Liquids in Stirred Tanks
5.2 Power Requirements
5.3 Vortex Formation and Surface Entrainment in Unbaffled and Baffled Vessels
5.4 Heat-Transfer in Stirred Vessels
5.5 Flow and Circulation
6 JET MIXED TANKS
6.1 Introduction
6.2 Recommended Configuration
6.3 Design Procedure
6.4 Design for Continuous Mixing
7 TUBULAR JET FLOW MIXERS FOR MISCIBLE LIQUIDS
7.1 Recommended Configurations
7.2 Mixer Design
7.3 Additional Considerations
8 MOTIONLESS MIXERS
8.1 Recommended Types
8.2 Correlations
TABLES
1 TYPICAL CONSTANTS FOR EQUATION (1)
2 POWER CURVES FIGURES AND CORRECTION FACTORS
3 VORTEX PARAMETERS, TURBINE, PROPELLER AND SAWTOOTH
4 CHARGING A HOT VESSEL WITH A COLD PRODUCT
5 INJECTING A HOT FLUID INTO THE JACKET OF A COLD VESSEL
6 TYPICAL DISCHARGE COEFFICIENTS
7 CONSTRAINTS FOR LAMINAR FLOW MOTIONLESS MIXERS
8 CONSTANTS FOR TURBULENT FLOW MOTIONLESS MIXERS
9 LENGTH FACTORS FOR HIGH VISCOSITY RATIOS
FIGURES
1 POWER NUMBERS FOR 45° ANGLED-BLADE TURBINES
2 CORRECTION FACTORS FOR DIAMETER RATIOS
3 BLADE ANGLE AND THICKNESS CORRECTION FACTORS
4 POWER NUMBERS FOR SINGLE 60° ANGLED-BLADE TURBINES
5 POWER NUMBERS FOR TWIN 60° ANGLED-BLADE TURBINES
6 POWER NUMBERS FOR TRIPLE 60° ANGLED-BLADE TURBINES
7 BAFFLE WIDTH AND NUMBER CORRECTION FACTORS FOR DIFFERENT DIAMETER RATIOS
8 CORRECTION FACTORS FOR SUBMERGENCE
9 CORRECTION FACTORS FOR SEPARATION
10 POWER NUMBERS FOR DISC-TURBINES
11 CORRECTION FACTORS FOR BAFFLES
12 CORRECTION FACTORS FOR BASE CLEARANCE
13 CORRECTION FACTORS FOR SUBMERGENCE
14 POWER NUMBERS FOR RETREAT-CURVE IMPELLERS
15 CORRECTION FACTORS FOR PARTIAL BAFFLES
16 POWER NUMBERS CORRECTION FACTORS FOR RETREAT-CURVE AND IMPELLERS H/T RATIOS OF 2.0
17 POWER NUMBERS FOR FLAT-BLADED TURBINES
18 BOTTOM CLEARANCE CORRECTION FACTOR
19 POWER NUMBERS FOR ANCHOR AND GATE AGITATORS
20 POWER NUMBERS FOR PROPELLERS
21 IMPELLER SPACING CORRECTION FACTORS
22 STANDARD NOTATION FOR VORTEX CALCULATIONS
23 VORTEX DATA FOR 2 - BLADED PADDLES
(W/D = 0.33, T/D = 2)
24 VORTEX CORRECTION FACTORS FOR PADDLES
25 JET DIRECTION
26 SINGLE JET MIXERS
27 MULTIJET MIXERS
28 SERIES ARRANGEMENT OF MIXERS
29 BATCH MIXERS
30 DESIGN PROCEDURE
31 EMPIRICAL FACTORS
32 RECIRCULATION ZONES
33 FRICTION FACTOR DATA FOR KENICS AND SULZER MIXERS
Centrifugal Compressors
SECTION ONE - ANTI-SURGE PROTECTION AND THROUGHPUT REGULATION
0 INTRODUCTION
1 SCOPE
2 MACHINE CHARACTERISTICS
2.1 Characteristics of a Single Compressor Stage
2.2 Characteristic of a Multiple Stage Having More
Than One Impeller
2.3 Use of Compressor Characteristics in Throughput
Regulation Schemes
3 MECHANISM AND EFFECTS OF SURGE
3.1 Basic Flow Instabilities
3.2 Occurrence of Surge
3.3 Intensity of Surge
3.4 Effects of Surge
3.5 Avoidance of Surge
3.6 Recovery from Surge
4 CONTROL SCHEMES INCLUDING SURGE PROTECTION
4.1 Output Control
4.2 Surge Protection
4.3 Surge Detection and Recovery
5 DYNAMIC CONSIDERATIONS
5.1 Interaction
5.2 Speed of Response of Antisurge Control System
6 SYSTEM EQUIPMENT SPECIFICATIONS
6.1 The Antisurge Control Valve
6.2 Non-return Valve
6.3 Pressure and flow measurement
6.4 Signal transmission
6.5 Controllers
7 TESTING
7.1 Determination of the Surge Line
7.2 Records
8 INLET GUIDE VANE UNITS
8.1 Application
8.2 Effect on Power Consumption of the Compressor
8.3 Effect of Gas Conditions, Properties and Contaminants
8.4 Aerodynamic Considerations
8.5 Control System Linearity
8.6 Actuator Specification
8.7 Avoidance of Surge
8.8 Features of Link Mechanisms
8.9 Limit Stops and Shear Links
APPENDICES
A LIST OF SYMBOLS AND PREFERRED UNITS
B WORKED EXAMPLE 1 COMPRESSOR WITH VARIABLE INLET PRESSURE AND VARIABLE GAS COMPOSITION
C WORKED EXAMPLE 2 A CONSTANT SPEED ~ STAGE COMPRESSOR WITH INTER-COOLING
D WORKED EXAMPLE 3 DYNAMIC RESPONSE OF THE ANTISURGE PROTECTION SYSTEM FOR A SERVICE AIR COMPRESSOR RUNNING AT CONSTANT SPEED
E EXAMPLE OF INLET GUIDE VANE REGULATION
FIGURES
2.1 TYPICAL COMPRESSOR STAGE CHARACTERISTIC PLOTTED WITH FLOW AT DISCHARGE CONDITIONS
2.2 TYPICAL COMPRESSOR STAGE CHARACTERISTIC PLOTTED WITH FLOW AT INLET CONDITIONS
2.3 PERFORMANCE CHARACTERISTICS OF A COMPRESSOR STAGE AT VARYING SPEEDS
2.4 SYSTEM WORKING POINT DEFINED BY INTERSECTION OF PROCESS AND COMPRESSOR CHARACTERISTICS
2.5 DISCHARGE THROTTLE REGULATION
2.6 BYPASS REGULATION
2.7 INLET THROTTLE REGULATION
2.8 INLET GUIDE VANE REGULATION
2.9 VARIABLE SPEED REGULATION
3.1 GAS PULSATION LEVELS FOR A CENTRIFUGAL COMPRESSOR
3.2 REPRESENTATION OF CYCLIC FLOW DURING SURGE OF LONG PERIOD
3.3 TYPICAL WAVEFORM OF DISCHARGE PRESSURE DURING SURGE
3.4 MULTIPLE SURGE LINE FOR A MULTISTAGE CENTRIFUGAL COMPRESSOR
3.5 TYPICAL MULTIPLE SURGE LINES FOR SINGLE STAGE AXIAL-FLOW COMPRESSOR
4.1 GENERAL SCHEMATIC FOR COMPRESSORS OPERATING IN PARALLEL TO FEED MULTIPLE USER PLANTS
4.2 ILLUSTRATION OF SAFETY MARGIN BETWEEN SURGE POINT AND SURGE PROTECTION POINT AT WHICH ANTISURGE SYSTEM IS ACTIVATED
4.3 ANTISURGE SYSTEM FOR COMPRESSOR WITH FLAT PERFO ..........
Batch Distillation
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 BACKGROUND TO THE DESIGN
4.1 General
4.2 Choice of batch/continuous operation
4.3 Boiling point curve and cut policy
4.4 Method of design
4.5 Scope of calculations required for design
5 SIMPLE BATCH DISTILLATION
6 FRACTIONAL BATCH DISTILLATION
6.1 General
6.2 Approximate methods
6.3 Rigorous design - use of a computer model
6.4 Other factors influencing the design
6.4.1 Occupation
6.4.2 Choice of Batch Rectification or Stripping
6.4.3 Batch size
6.4.4 Initial estimate of cut policy
6.4.5 Liquid Holdup
6.4.6 Total reflux operation and heating-up time
6.4.7 Column operating pressure
6.5 Optimum Design of the Batch Still
6.6 Special design problems
7 GENERAL ASPECTS OF EQUIPMENT DESIGN
7.1 Kettle reboilers
7.2 Column Internals
7.3 Condensers and reflux split boxes
8 PROCESS CONTROL AND INSTRUMENTATION IN
BATCH DISTILLATION
9 MECHANICAL DESIGN FEATURES
10 BIBLIOGRAPHY
APPENDICES
A McCABE - THIELE METHOD - TYPICAL EXAMPLE
Fixed Bed Reactor Scale-up Checklist
The purpose of this checklist is to identify the stages and potential problems associated with the scale up of fixed bed reactors from the drawing board to the full scale plant, and to determine how they should be checked.
The checking can be done using various methods. These are:
• Literature data.
• Lab testing.
• Calculation.
• Modeling.
• Semi-tech testing.
• Piloting or Sidestream testing.
Identifying the stages that need to be addressed for a particular catalyst/reactor development will help in estimating the time needed for the development of the reactor
"SEDIMENTATION"
INTRODUCTION - THE PHENOMENON OF SEDIMENTATION
Sedimentation is the physical process whereby solid particles, of greater density than their suspending medium, will tend to separate into regions of higher concentration under the influence of gravity. As a solids/liquids separation technique it therefore possesses the great advantage of utilizing a natural, and therefore costless, driving force. This section of the suspension processing Guide is Intended to provide an Introduction to the science of the subject, and the means to judge where and how best to exploit sedimentation as a separation (or other processing) technique.
As a scientific discipline the subject of sedimentation is vast with perspectives ranging from the field of chemical engineering through to theoretical physics being covered In the literature [1-11]. Good reviews of the subject, with a bias towards the engineering aspects, have been written by Fitch and Koz [12, 13]. A short summary of some of the more relevant contributions from the literature is also provided in GBHE-SPG-PEG-302 “Basic Principles & Test Methods”, of the Suspensions Processing Guides.
.
The sedimentation process is traditionally divided into ..."
Data Sources For Calculating Chemical Reaction EquilibriaGerard B. Hawkins
Data Sources For Calculating Chemical Reaction Equilibria
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 BACKGROUND TO THEORY
5 BIBLIOGRAPHY
VLE Data - Selection and Use
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 DIAGRAMMATIC REPRESENTATION OF IDEAL
AND NON-IDEAL SYSTEMS
4.1 Ideal Mixtures
4.2 Non-Ideal Mixtures
5 REVIEW OF VLE MODELS
5.1 Ideal Behavior in Both Phases
5.2 Liquid Phase Non-Idealities
5.3 High Pressure Systems
5.4 Special Models
6 SETTING UP A VLE MODEL
6.1 Define Problem
6.2 Select Data
6.3 Select Correlation(s)
6.4 Produce Model
7 AVOIDING PITFALLS
7.1 Experimental Data is Better than Estimates
7.2 Check Validity of Fitted Model
7.3 Check Limitations of Estimation Methods
7.4 Know Your System
7.5 Appreciate Errors and Effects
7.6 If in Doubt – Ask
8 A CASE STUDY
8.1 The Problem
8.2 The System
8.3 Data Available
8.4 Selected Correlation
8.5 Simulation
8.6 Selection of Model
9 RECOMMENDED READING
10 VLE EXPERTS IN GBHE
APPENDICES
A USE OF EXTENDED ANTOINE EQUATION
B USE OF WILSON EQUATION
C USEFUL METHODS OF ESTIMATING
D EQUATIONS OF STATE FOR VLE CALCULATIONS
TABLES
1 SUMMARY OF VLE METHODS
2 LIST OF USEFUL REFERENCES
FIGURES
1 VAPOR-LIQUID EQUILIBRIUM - IDEAL SOLUTION
BEHAVIOR
2 VAPOR-LIQUID EQUILIBRIUM - A GENERALISED
Y-X DIAGRAM
3 VAPOR-LIQUID EQUILIBRIUM - MINIMUM BOILING
AZEOTROPE
4 VAPOR-LIQUID EQUILIBRIUM - MAXIMUM BOILING
AZEOTROPE
5 VAPOR-LIQUID EQUILIBRIUM - MINIMUM BOILING
AZEOTROPE -TWO LIQUID PHASES
6 SENSITIVITY TO ERROR IN VLE DATA (BASED ON FENSKE EQUATION)
7(a) FITTING WILSON 'A' VALUES TO VLE DATA - CASE A
7(b) FITTING WILSON 'A' VALUES TO VLE DATA - CASE B
7(c) FITTING WILSON 'A' VALUES TO VLE DATA - CASE C
Mixing of Immiscible Liquids
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 EQUIPMENT
4.1 Agitated Tanks
4.2 Flow Mixers
4.3 'High Shear' Mixers
5 SYSTEM PHYSICAL PROPERTIES
5.1 Density
5.2 Viscosity
5.3 Interfacial Tension
6 STIRRED VESSELS
6.1 Design for Complete Dispersion
6.2 Prediction of Phase Inversion
6.3 Design for Mass Transfer
6.4 Design for Dispersed Phase Mixing
6.5 Hold-Up in Continuous Vessels
7 FLOW MIXERS
7.1 Design for Turbulent Conditions
7.2 Design for Laminar Conditions
TABLES
1 REYNOLDS NUMBER RANGES
FIGURES
1 STANDARD TANK CONFIGURATION
2 EXPERIMENTAL RELATIONSHIP BETWEEN MASS
TRANSFER COEFFICIENT AND POWER DENSITY
Gas - Liquid Reactors
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 PRELIMINARY CONSIDERATIONS
4.1 Preliminary Equipment Selection
4.2 Equipment for Low Viscosity Liquids
4.3 Equipment for High Viscosity Liquids
5 REACTOR DESIGN
6 ESSENTIAL THEORY
6.1 Rate and Yield Determining Steps
6.2 Chemical and Physical Rates
6.3 Modification for Exothermic and Complex Reactions
6.4 Preliminary Selection of Reactor Type
7 EXPERIMENTAL DETERMINATION OF REGIME
7.1 Direct Measurement of Reaction Kinetics
7.2 Laboratory Gas-Liquid Reactor Experiments
8 EQUILIBRIUM AND DIFFUSIVITY DATA SOURCES
9 OVERALL EFFECTS
9.1 Liquid Flow Patterns
9.2 Scale of Mixing
9.3 Gas Flow Pattern : Mean Driving Force for Mass Transfer
9.4 Gas-Liquid Reactor Modeling
9.5 Heat Transfer
9.6 Materials of Construction
9.7 Foaming
10 FINAL CHOICE OF REACTOR TYPE
11 SCALE-UP AND SPECIFICATION OF GAS-LIQUID
REACTORS
11.1 Bubble Columns
11.2 Packed Columns
11.3 Trickle Beds
11.4 Plate or Tray Columns
11.5 Spray Columns
11.6 Wiped Film
11.7 Spinning Film Reactors
11.8 Stirred Vessels
11.9 Plunging Jet
11.10 Surface Aerator
11.11 Static Mixers
11.12 Ejectors, Venturis and Orifice Plates
11.13 3-Phase Fluidized Bed
12 BIBLIOGRAPHY
TABLES
1 REGIMES OF GAS-LIQUID MASS TRANSFER WITH ISOTHERMAL CHEMICAL REACTION
2 REGIMES OF GAS-LIQUID MASS TRANSFER IGNORING LARGE EXOTHERMS OR OTHER COMPLICATIONS
3 COMPARATIVE MASS TRANSFER PERFORMANCE OF CONTACTING DEVICES
4 COMPARATIVE MASS TRANSFER DATA
5 CHOICE OF GAS-LIQUID REACTOR TYPE
FIGURES
1 RATE AND YIELD DETERMINING STEPS
2 ENHANCEMENT FACTOR vs HATTA NUMBER
3 ENHANCEMENT FACTOR vs HATTA NUMBER : EFFECT OF THERMAL & OTHER FACTORS
4 REACTORS FOR LIQUID-PHASE KINETICS
MEASUREMENT
5 EXPERIMENTS TO DETERMINE THE OPERATING
REGIME
6 EXPERIMENTS DETERMINE THE OPERATING REGIME WHERE A SOLID CATALYST IS INVOLVED
7 THE MIXED ZONES IN LOOPS' MODEL FOR STIRRED REACTORS
Residence Time Distribution Data
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 BASICS OF RESIDENCE TIME DISTRIBUTION DATA
5 USE OF RESIDENCE TIME DISTRIBUTION DATA
5.1 Micromixing and Macromixing
5.2 Example 1 - Reaction is First Order
5.3 Example 2 - Reaction is Second Order
5.4 Complex Reactions and Residence Time Distribution
5.5 Examples
6 RESIDENCE TIME MEASUREMENTS WITH
RADIOISOTOPES
6.1 General
6.2 Types of Reactors
6.3 Models Based on Method of Moments
6.4 Non-impulse Input
6.5 Diagnosis of Problems
6.6 Commercial Radioisotope Service
7 BIBLIOGRAPHY
Control of Continuous Distillation Columns
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 GENERAL DESCRIPTION OF A DISTILLATION COLUMN
5 REGULATORY CONTROL
5.1 Composition Control
5.2 Mass Balance Control
5.3 Design of Feedback Control Systems
5.4 Pressure and Condensation Control
5.5 Reboiler Control
6 DISTURBANCE COMPENSATION
6.1 Feed-forward Control
6.2 Cascade Control
6.3 Internal Reflux Control
7 CONSTRAINT CONTROL
7.1 Override Controls
7.2 Flooding
7.3 Limiting Control
8 MORE ADVANCED TOPICS
8.1 Temperature Position Control
8.2 Inferential Measurement
8.1 Floating Pressure Control
8.2 Model Based Predictive Control
8.1 Control of Side-streams
8.2 Extractive/Azeotropic Systems
9 REFERENCES
TABLES
1 SYMPTOMS OF IMBALANCE AND THE REGULATORY VARIABLES
2 PRACTICAL LINKAGES BETWEEN CONTROL
(P, R, B, C) AND REGULATION VARIABLES
(h, r, d, b, c, v)
3 COMPOSITION REGULATION
4 COMPOSITION REGULATION - VERY SMALL FLOWS
Shortcut Methods of Distillation Design
0 INTRODUCTION/PURPOSE
1 SCOPE
2 ESTIMATIONOF PLATEAGE AND REFLUX
REQUIREMENTS
2.1 Generalized Procedure for Nmin and Rmin
2.2 Equation based Procedure for Nmin and Rmin
3 PREDICTION OF OVERALL PLATE EFFICIENCY
4 SIZING OF MAIN PLANT ITEMS
4.1 Column Diameter
4.2 Surface Area of Condensers and Reboilers
FIGURES
1 NON-IDEAL EQUILIBRIUM CURVE
2 AT A GLANCE CHART BASED ON FENSKE,
UNDERWOOD
3 PLATE EFFICIENCY CORRELATION OF O’CONNEL
Pressure Systems
CONTENTS
0 INTRODUCTION
1 SCOPE
2 DEFINITIONS ADDITIONAL TO THOSE IN THE EP GLOSSARY
2.1 PRESSURE VESSEL
2.2 ATMOSPHERIC PRESSURE STORAGE TANK
2.3 VESSEL
2.4 PIPING SYSTEM
2.5 NON-PRESSURE PROTECTIVE DEVICE
2.6 ASSOCIATED RELIEF EQUIPMENT
3 APPLICATION OF PRINCIPLES
3.1 IMPLEMENTATION OF PEG 4
3.2 DESIGN, MANUFACTURE, REPAIR AND MODIFICATION
3.3 VERIFICATION OF DESIGN
3.4 GBHE REGISTRATION AND RECORDS
3.5 PERIODIC EXAMINATION
4 AUDITING
4.1 General
4.2 Scope of Audit
APPENDICES
A EQUIPMENT WHICH MAY BE EXEMPTED FROM GBHE REGISTRATION
C DOCUMENTATION FOR INCLUSION IN FILES OF REGISTERED EQUIPMENT
D ADDITIONAL REQUIREMENTS FOR THE PERIODIC EXAMINATION OF SPECIAL CATEGORIES OF EQUIPMENT
E DIAGRAMMATIC REPRESENTATION OF PRESSURE SYSTEMS PROCEDURES
F DECISION TREE FOR REGISTRATION OF PIPING SYSTEMS
G REGISTERED EQUIPMENT WHICH MAY BE EXEMPTED FROM DESIGN VERIFICATION
TABLES
1 REGISTERED VESSELS AND PIPING SYSTEMS: MAXIMUM EXAMINATION INTERVALS
2 EQUIPMENT TO BE CONSIDERED FOR CATEGORY LLT
FIGURES
1 SIMPLE PRESSURE RELIEF ARRANGEMENT
2 COMPLEX PRESSURE RELIEF ARRANGEMENT
DOCUMENTS REFERRED TO IN THIS INFORMATION FOR ENGINEERS DOCUMENT
Chemical Process Conception
0 INTRODUCTION / PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 PRODUCT STRATEGY
4.1 General
4.2 Market for the Product
4.3 Production Costs
4.4 Process Technology
5 PRELIMINARY PROCESS INFORMATION
6 REACTION AND REACTOR
6.1 Batch vs Continuous
6.2 Multiple Reactors
7 RECYCLE
7.1 Recycle Structure
7.2 Classification of Chemicals
7.3 Effect of Recycle
7.4 Preliminary Estimation of Conversion
8 REACTOR TYPE AND PERFORMANCE
8.1 Conversion-Yield Effects
8.2 Heat Effects
8.3 Equilibrium Effects
8.4 Kinetic Effects
8.5 More Help with Reactor Design
9 SEPARATION SYSTEM
10 REVIEW
11 BIBLIOGRAPHY AND REFERENCES
11.1 Preliminary Flowsheeting
11.2 Physical Properties
11.3 Reactors
11.4 Separation
11.5 Costing
APPENDICES
A BASIC REACTOR SYSTEM DESIGN
B DISCUSSION BETWEEN A CHEMIST AND A
CHEMICAL ENGINEER
C BASIC SEPARATION STRATEGY
TABLES
1 CLASSIFICATION OF MATERIALS
FIGURES
1 FLOWCHART OF THE ITERATIVE PROCEDURE REQUIRED IN PROCESS AND PRODUCT SELECTION AND DEVELOPMENT
Similar to Interpretation And Correlation Of Viscometric Data (20)
GAS DISPERSION - A Definitive Guide to Accidental Releases of Heavy GasesGerard B. Hawkins
GAS DISPERSION - A Definitive Guide to Accidental Releases of Heavy Gases
This Process Safety Guide has been written with the aim of assisting process engineers, hazard analysts and environmental advisers in carrying out gas dispersion calculations. The Guide aims to provide assistance by:
• Improving awareness of the range of dispersion models available within GBHE, and providing guidance in choosing the most appropriate model for a particular application.
• Providing guidance to ensure that source terms and other model inputs are correctly specified, and the models are used within their range of applicability.
• Providing guidance to deal with particular topics in gas dispersion such as dense gas dispersion, complex terrain, and modeling the chemistry of oxides of nitrogen.
• Providing general background on air quality and dispersion modeling issues such as meteorology and air quality standards.
• Providing example calculations for real practical problems.
SCOPE
The gas dispersion guide contains the following Parts:
1 Fundamentals of meteorology.
2 Overview of air quality standards.
3 Comparison between different air quality models.
4 Designing a stack.
5 Dense gas dispersion.
6 Calculation of source terms.
7 Building wake effects.
8 Overview of the chemistry of the oxides of nitrogen.
9 Overview of the ADMS complex terrain module.
10 Overview of the ADMS deposition module.
11 ADMS examples.
12 Modeling odorous releases.
13 Bibliography of useful gas dispersion books and reports.
14 Glossary of gas dispersion modeling terms.
Appendix A : Modeling Wind Generation of Particulates.
APPENDIX B TABLE OF PROPERTY VALUES FOR SPECIFIC CHEMICALS
Calculation of an Ammonia Plant Energy Consumption: Gerard B. Hawkins
Calculation of an Ammonia Plant Energy Consumption:
Case Study: #06023300
Plant Note Book Series: PNBS-0602
CONTENTS
0 SCOPE
1 CALCULATION OF NATURAL GAS PROCESS FEED CONSUMPTION
2 CALCULATION OF NATURAL GAS PROCESS FUEL CONSUMPTION
3 CALCULATION OF NATURAL GAS CONSUMPTION FOR PILOT BURNERS OF FLARES
4 CALCULATION OF DEMIN. WATER FROM DEMIN. UNIT
5 CALCULATION OF DEMIN. WATER TO PACKAGE BOILERS
6 CALCULATION OF MP STEAM EXPORT
7 CALCULATION OF LP STEAM IMPORT
8 DETERMINATION OF ELECTRIC POWER CONSUMPTION
9 DETERMINATION OF THE TOTAL ENERGY CONSUMPTION OF THE AMMONIA PLANT ISBL
10 ADJUSTMENT OF ELECTRIC POWER CONSUMPTION FOR TEST RUN CONDITIONS
11 CALCULATION OF AMMONIA SHARE IN MP STEAM CONSUMPTION IN UTILITIES
12 CALCULATION OF AMMONIA SHARE IN ELECTRIC POWER CONSUMPTION IN UTILITIES
13 DETERMINATION OF THE TOTAL ENERGY CONSUMPTION OF THE AMMONIA PLANT OSBL
14 DETERMINATION OF THE TOTAL ENERGY CONSUMPTION OF THE AMMONIA PLANT
Ammonia Plant Technology
Pre-Commissioning Best Practices
GBHE-APT-0102
PICKLING & PASSIVATION
CONTENTS
1 PURPOSE OF THE WORK
2 CHEMICAL CONCEPT
3 TECHNICAL CONCEPT
4 WASTES & SAFETY CONCEPT
5 TARGET RESULTS
6 THE GENERAL CLEANING SEQUENCE MANAGEMENT
6.6.1 Pre-cleaning or “Physical Cleaning
6.6.2 Pre-rinsing
6.6.3 Chemical Cleaning
6.6.4 Critical Factors in Cleaning Success
6.6.5 Rinsing
6.6.6 Inspection and Re-Cleaning, if Necessary
7 Systems to be treated by Pickling/Passivation
Ammonia Plant Technology
Pre-Commissioning Best Practices
Piping and Vessels Flushing and Cleaning Procedure
CONTENTS
1 Scope
2 Aim/purpose
3 Responsibilities
4 Procedure
4.1 Main cleaning methods
4.1.1 Mechanical cleaning
4.1.2 Cleaning with air
4.1.3 Cleaning with steam (for steam networks only)
4.1.4 Cleaning with water
4.2 Choice of the cleaning method
4.3 Cleaning preparation
4.4 Protection of the devices included in the network
4.5 Protection of devices in the vicinity of the network
4.6 Water flushing procedure
4.6.1 Specific problems of water flushing
4.6.2 Preparation for water flushing
4.6.3 Performing a water flush
4.6.4 Cleanliness criteria
4.7 Air blowing procedure
4.7.1 Specific problems of air blowing
4.7.2 Preparation for air blowing
4.7.3 Performing air blowing
4.7.4 Cleanliness checks
4.8 Steam blowing procedure
4.8.1 Specific problems of steam blowing
4.8.2 Preparation for steam blowing
4.8.3 Performing steam blowing
4.8.4 Cleanliness checks
4.9 Chemical cleaning procedure
4.9.1 Specific problems of cleaning with a chemical solution
4.9.2 Preparation for chemical cleaning
4.9.3 Performing a chemical cleaning
4.9.4 Cleanliness criteria
4.10 Re-assembly - general guideline
4.11 Preservation of flushed piping
PRACTICAL GUIDE ON THE SELECTION OF PROCESS TECHNOLOGY FOR THE TREATMENT OF A...Gerard B. Hawkins
PRACTICAL GUIDE ON THE SELECTION OF PROCESS TECHNOLOGY FOR THE TREATMENT OF AQUEOUS ORGANIC EFFLUENT STREAMS
CONTENTS
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
3.1 IPU
3.2 AOS
3.3 BODs
3.4 COD
3.5 TOC
3.6 Toxicity
3.7 Refractory Organics/Hard COD
3.8 Heavy Metals
3.9 EA
3.10 Biological Treatment Terms
3.11 BATNEEC
3.12 BPEO
3.13 EQS/LV
3.14 IPC
3.15 VOC
3.16 F/M Ratio
3.17 MLSS
3.18 MLVSS
4 DESIGN/ECONOMIC GUIDELINES
5 EUROPEAN LEGISLATION
5.1 General
5.2 Integrated Pollution Control (IPC)
5.3 Best Available Techniques Not Entailing Excessive Costs (BATNEEC)
5.4 Best Practicable Environmental Option (BPEO)
5.5 Environmental Quality Standards(EQS)
6 IPU EXIT CONCENTRATION
7 SITE/LOCAL REQUIREMENTS
8 PROCESS SELECTION PROCEDURE
8.1 Waste Minimization Techniques (WMT)
8.2 AOS Stream Definition
8.3 Technical Check List
8.4 Preliminary Selection of Suitable Technologies
8.5 Process Sequences
8.6 Economic Evaluation
8.7 Process Selection
APPENDICES
A DIRECTIVE 76/464/EEC - LIST 1
B DIRECTIVE 76/464/EEC - LIST 2
C THE EUROPEAN COMMISSION PRIORITY CANDIDATE LIST
D THE UK RED LIST
E CURRENT VALUES FOR EUROPEAN COMMUNITY ENVIRONMENTAL QUALITY STANDARDS AND CORRESPONDING LIMIT VALUES
F ESTABLISHED TECHNOLOGIES
G EMERGING TECHNOLOGY
H PROPRIETARY/LESS COMMON TECHNOLOGIES
J COMPARATIVE COST DATA
PRACTICAL GUIDE ON THE REDUCTION OF DISCHARGES TO ATMOSPHERE OF VOLATILE ORGA...Gerard B. Hawkins
PRACTICAL GUIDE ON THE REDUCTION OF DISCHARGES TO ATMOSPHERE OF VOLATILE ORGANIC COMPOUNDS (VOCs)
FOREWORD
CONTENTS
1 INTRODUCTION
2 THE NEED FOR VOC CONTROL
3 CONTROL AT SOURCE
3.1 Choice or Solvent
3.2 Venting Arrangements
3.3 Nitrogen Blanketing
3.4 Pump Versus Pneumatic Transfer
3.5 Batch Charging
3.6 Reduction of Volumetric Flow
3.7 Stock Tank Design
4 DISCHARGE MEASUREMENT
4.1 By Inference or Calculation
4.2 Flow Monitoring Equipment
4.3 Analytical Instruments
4.4 Vent Emissions Database
5 ABATEMENT TECHNOLOGY
5.1 Available Options
5.2 Selection of Preferred Option
5.3 Condensation
5.4 Adsorption
5.5 Absorption
5.6 Thermal Incineration
5.7 Catalytic Oxidation
5.8 Biological Filtration
5.9 Combinations of Process technologies
5.10 Processes Under Development
6 GLOSSARY OF TERMS
7 REFERENCES
Appendix 1. Photochemical Ozone Creation Potentials
Appendix 2. Examples of Adsorption Preliminary Calculations
Appendix 3. Example of Thermal Incineration Heat and Mass Balance
Appendix 4. Cost Correlations
EMERGENCY ISOLATION OF CHEMICAL PLANTS
CONTENTS
1 Introduction
2 When should Emergency Isolation Valves be Installed
3 Emergency Isolation Valves and Associated Equipment
3.1 Installations on existing plant
3.2 Actuators
3.3 Power to close or power to open
3.4 The need for testing
3.5 Hand operated Emergency Valves
3.6 The need to stop pumps in an emergency
3.7 Location of Operating Buttons
3.8 Use of control valves for Isolation
4 Detection of Leaks and Fires
5 Precautions during Maintenance
6 Training Operators to use Emergency Isolation Valves
7 Emergency Isolation when no remotely operated valve is available
References
Glossary
Appendix I Some Fires or Serious Escapes of Flammable Gases or Liquids that could have been controlled by Emergency Isolation Valves
Appendix II Some typical Installations
Burner Design, Operation and Maintenance on Ammonia PlantsGerard B. Hawkins
Burner Design, Operation and Maintenance on Ammonia Plants
Brief History
Reformer Burner Types/Design
Types of Reformers
Combustion Characteristics
Excess Air/Heater Efficiency
Maintenance, Good Practice
Low Nox Equipment
Summary
Debottlenecking Claus Sulfur Recovery Units: An Investigation of the applicat...Gerard B. Hawkins
Debottlenecking Claus Sulfur Recovery Units: An Investigation of the application of Zinc Titanates
1 Executive Summary
2 Claus Process
2.1 Partial Combustion Claus
2.2 Split Flow Claus
2.3 Sulfur Recycle Claus
3 Zinc Titanates
4 Application of Zinc Titanate to Debottleneck Partial Combustion Claus by 10%
4.1 Process
4.2 ASPEN Modeling Results
4.3 Cost of Zinc Titanate Bed Installation
4.3.1 Basis of Costing
4.3.2 Zinc Titanate Beds
4.3.3 Regen Cooler
4.3.4 Blowers
4.3.5 Results
4.4 Alternative Debottlenecking Technology for Partial Combustion Claus
4.5 Cost of 10% Debottlenecking Using COPE Process
5 Debottlenecking Claus Split Flow System by 10% with Zinc Titanates
6 Debottlenecking Claus Sulfur Recycle System With Zinc Titanate
7 Effect of Zinc Titanate Debottlenecking on Existing Tail; Gas Treatment Systems
7.1 Selectox
7.2 SuperClaus99
7.3 Superclaus 99.5
7.4 SCOT Process
7.5 Zinc Titanate as a Claus Tail Gas Treatment
7.6 H2S Removal Efficiency With Zinc Titanate
8 Effects on COS and CS2 Formation
9 Questions for further Investigation
FIGURES
Figure 1 Claus Unit and TGCU
Figure 2 Claus Process
Figure 3 Typical Claus Sulfur Recovery Unit
Figure 4 Two-Stage Claus SRU
Figure 5 The Super Claus Process
Figure 6 SCOT
Figure 7 SCOT/BSR-MDEA (or clone) TGCU
REFERENCES: PATENTS
US4333855_PROMOTED_ZINC_TITANATE_CATALYTIC_AGENT
US4394297_ZINC_TITANATE_CATALYST
US6338794B1_DESULFURIZATION_ZINC_TITANATE_SORBENTS
Catalyst Catastrophes in Syngas Production - I
The Hazards
Review incidents by reactor
Purification….
Through the various unit operations to
Ammonia synthesis
Nickel Carbonyl
Pre-reduced catalysts
Discharging catalysts
Conclusion
Integration of Special Purpose Centrifugal Pumps into a ProcessGerard B. Hawkins
Integration of Special Purpose Centrifugal Pumps into a Process
CONTENTS
1 SCOPE
2 PRELIMINARY CHOICE OF PUMP
SECTION A - INLET CONDITIONS
Al Calculation of Basic Nett Positive Suction Head (NPSH)
A2 Correction to Basic NPSH for Temperature Rise at Pump Inlet
A3 Correction to Basic NPSH for Acceleration Head
A4 Calculation of Available NPSH
A5 Correction to NPSH for Fluid Properties
A6 Calculation of Suction Specific Speed
A7 Priming
A8 Submergence
SECTION B – FLOW / HEAD RATING SEQUENCE
B1 Calculation of Static Head
B2 Calculation of Margins for Control
B3 Calculation of Q-H Duty
B4 Stability and Parallel Operation
B5 Corrections to Q-H Duty for Fluid Properties
B6 Guide to Pump Type and Speed
SECTION C – DRIVER POWER RATING
C1 Estimation of Pump Efficiency
C2 Calculation of Absorbed Power
C3 Calculation of Driver Power Rating
C4 Preliminary Power Ratings of Electric Motors
C5 Starting Conditions for Electric Motors
C6 Reverse Flow and Reverse Rotation
SECTION D - CASING PRESSURE RATING
D1 Calculation of Maximum Inlet Pressure
D2 Calculation of Differential Pressure
D3 Pressure Waves
D4 Pressure due to Liquid Thermal Expansion
D5 Casing Hydrostatic Test Pressure
SECTION E – SEALING CONSIDERATIONS
E1 Preliminary Choice of Seal
E2 Fluid Attributes
E3 Definition of Flushing Arrangements
APPENDICES
A RELIABILITY CLASSIFICATION
B SYMBOLS AND PREFERRED UNITS
DOCUMENTS REFERRED TO IN THIS ENGINEERING DESIGN GUIDE
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SAP Sapphire 2024 - ASUG301 building better apps with SAP Fiori.pdfPeter Spielvogel
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GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
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State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
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PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
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UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
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Interpretation And Correlation Of Viscometric Data
1. GBH Enterprises, Ltd.
Process Engineering Guide:
GBHE-PEG-FLO-302
Interpretation and Correlation of
Viscometric Data
Information contained in this publication or as otherwise supplied to Users is
believed to be accurate and correct at time of going to press, and is given in
good faith, but it is for the User to satisfy itself of the suitability of the information
for its own particular purpose. GBHE gives no warranty as to the fitness of this
information for any particular purpose and any implied warranty or condition
(statutory or otherwise) is excluded except to the extent that exclusion is
prevented by law. GBHE accepts no liability resulting from reliance on this
information. Freedom under Patent, Copyright and Designs cannot be assumed.
Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
2. Process Engineering Guide:
Estimation of Pressure Drop in
Pipe Systems
CONTENTS
0
INTRODUCTION/PURPOSE
4
1
SCOPE
4
2
FIELD OF APPLICATION
4
3
DEFINITIONS
4
4
NON-NEWTONIAN FLUID BEHAVIOR
4
4.1
4.2
4.3
Introduction
Classification of Non-Newtonian Fluids
Caution
4
6
14
5
VISCOMETER MEASUREMENTS FOR
TIME-INDEPENDENT FLUIDS
16
5.1
5.2
5.3
5.4
5.5
5.6
Concentric Cylinder Viscometers
Cone and Plate Viscometers
Parallel Plate Viscometer
Tube or Capillary Viscometer
Checks for Consistency of Data and Interpretation
Estimate of Process Shear Rate
16
17
18
18
20
23
6
MODEL FITTING TO FLOW CURVES
24
6.1
6.2
6.3
6.4
Power Law
Bingham Plastic
Direct use of Numerical Data
Rheological Models Involving Temperature Dependence
24
25
26
26
Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
3. 7
CHARACTERIZATION OF TIME-DEPENDENT LIQUIDS
29
7.1
7.2
7.3
7.4
7.4
Sample Loading
Tests at Constant Shear Rate
Dynamic Response Measurement
Changes in Shear Rate
Concluding Remarks
29
29
30
31
33
8
TECHNIQUES FOR CHARACTERIZATION OF
VISCOELASTIC LIQUIDS
33
8.1
8.2
8.3
8.4
Stress Relaxation
Oscillatory Shear Measurements
Normal Force Measurement
Elongational Viscosity Measurement
33
33
33
34
9
NOMENCLATURE
34
10
BIBLIOGRAPHY
35
APPENDICES
A
EQUATIONS FOR VISCOMETERS
36
A.1
EQUATIONS FOR CONCENTRIC CYLINDER
VISCOMETERS
36
A.2
EQUATIONS FOR CONE AND PLATE VISCOMETERS
38
A.3
EQUATIONS FOR PARALLEL PLATE VISCOMETER
39
A.4
EQUATIONS FOR TUBE OR CAPILLARY VISCOMETER
39
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
4. TABLES
1
NON-NEWTONIAN FLUID BEHAVIOR
5
2
SOME EXAMPLES OF NON-NEWTONIAN MATERIALS
15
3
SUMMARY OF CHARACTERISTICS OF CONCENTRIC
CYLINDER VISCOMETERS
16
SUMMARY OF CHARACTERISTICS OF CONE AND PLATE
VISCOMETERS
18
SUMMARY OF CHARACTERISTICS OF TUBE OR CAPILLARY
VISCOMETERS
18
SUMMARY OF CONSISTENCY CHECKS
20
4
5
6
FIGURES
1
SHEARING BETWEEN PARALLEL PLANES
5
2
SIMPLE TESTS OF A QUALITATIVE NATURE WHICH INDICATE
WHETHER OR NOT A LIQUID DEPARTS FROM NEWTONIAN
BEHAVIOR
7
3
VISCOELASTIC MATERIAL BEHAVIOR
8
4
PSEUDOPLASTIC BEHAVIOR
10
5
PSEUDOPLASTIC BEHAVIOR
10
6
LIQUIDS WITH ZERO AND INFINITE SHEAR VISCOSITIES
11
7
DILATANT BEHAVIOR
11
8
LIQUID HAVING A YIELD STRESS
12
9
TIME-DEPENDENT LIQUID BEHAVIOR
13
10
CO-AXIAL OR CONCENTRIC CYLINDER VISCOMETER
17
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
5. 11
CONE AND PLATE GEOMETRY
17
12
TUBE OR CAPILLARY VISCOMETER
19
13
DETERMINATION OF END EFFECTS IN TUBE VISCOMETERS
21
14
DERIVATION OF END EFFECTS FOR PRESSURE DRIVEN TUBE
VISCOMETERS
22
15
TYPICAL DATA FOR THIXOTROPIC FLUIDS
22
16
APPLICATION OF POWER LAW
24
17
TYPICAL IDEAL BINGHAM PLASTIC BEHAVIOR
25
18
NON-LINEAR BINGHAM PLASTIC BEHAVIOR
26
19
EFFECT OF TEMPERATURE
27
20
TYPICAL CONSTANT SHEAR RATE DATA
30
21
DYNAMIC RESPONSE DATA
31
22
CHANGE IN SHEAR RATE DATA
31
23
OTHER FORMS OF RESPONSE TO CHANGES IN SHEAR RATE 32
24
TORQUE SPEED PLOTS
37
25
TORQUE vs SPEED PLOT FOR BINGHAM PLASTICS
38
DOCUMENTS REFERRED TO IN THIS PROCESS
ENGINEERING GUIDE
40
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
6. 0
INTRODUCTION/PURPOSE
This guide is one of a series of guides on non-Newtonian flow prepared for GBH
Enterprises.
1
SCOPE
This document provides guidance on the interpretation of viscometric data
obtained from different measuring devices and their correlation into forms usable
for design purposes. It does not cover the design of pipes or equipment handling
non-Newtonian fluids.
2
FIELD OF APPLICATION
This Guide applies to Process Engineers in GBH Enterprises.
3
DEFINITIONS
For the purpose of this Guide, the following definitions apply:
Viscometer
An apparatus used to measure the viscosity of a liquid.
Rheometer
An apparatus used to measure other flow behavior
properties (e.g.elastic properties) in addition to the viscous
properties.
With the exception of terms used as proper nouns or titles, those terms with initial
capital letters which appear in this document and are not defined above are
defined in the Glossary of Engineering Terms.
4
NON-NEWTONIAN FLUID BEHAVIOR
4.1
Introduction
All gases, pure liquids and dilute inorganic solutions are Newtonian in their flow
behavior. By definition, such materials obey Newton's law of viscosity, i.e. when
sheared in laminar flow, the shear stress (see Note 1) is directly proportional to
the shear rate (see Note 2 and Figure 1).
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
7. Notes:
(1)
Shear stress:
shear force per unit area causing the
shearing motion. (N/m2)
(2)
Shear rate:
equivalent to the velocity gradient in
one-dimensional shearing motion. (s -1)
(3)
Viscosity:
the ratio of shear stress / shear rate (Ns/m2)
1 Ns/m2 = 1 Pa.s = 1 kg/s.m = 1000 cP = 10 P
FIGURE 1
SHEARING BETWEEN PARALLEL PLANES
The proportionality constant, µ1 is termed the shear velocity or simply viscosity
and for a Newtonian fluid it is constant and independent of shear rate,
.
The viscosity, however, varies strongly with temperature and to a lesser extent
with pressure.
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
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8. Thus for a Newtonian liquid (such as ethanol or petrol) the laminar viscosity, µ, is
a constant which does not vary with the processing conditions (provided the
temperature and pressure remain constant). Such materials may be pumped at
any flowrate, stirred at any speed and the viscosity will have a unique value
provided laminar flow is maintained. In turbulent flow, even for a Newtonian
liquid, the shear stress is no longer directly proportional to the shear rate. It is
possible to define a 'turbulent viscosity' as the ratio of shear stress to shear rate,
but its value will depend on the shear rate. Note that the viscosity used in the
definition of Reynolds number is the laminar viscosity, even under turbulent
conditions.
However, many industrial liquids exhibit 'non-Newtonian' characteristics, i.e. in
laminar flows, Newton's law of viscosity is inadequate to describe their flow
behavior. Such materials are shown in Table 1.
TABLE 1
NON-NEWTONIAN FLUID BEHAVIOR
Some Fluids Which Exhibit Non-Newtonian
Fluid Behavior
Suspensions
Slurries
Pastes
Creams
Gels
Greases
Waxes
Plastics
Rubbers
Paints
Foodstuffs
Polymer Solutions
The listing in Table 1, is by no means exhaustive, but if any liquid is two-phase
(e.g. emulsions, pastes, slurries) or if the liquid contains polymeric materials
(plastics, rubbers, polymer solutions), then non-Newtonian behavior should be
suspected.
The only sure way to determine whether or not a liquid is non-Newtonian is to
take measurements in a Viscometer or Rheometer of the shear stress-shear rate
behavior of the material. However, some simple tests of a qualitative nature are
given in Figure 2 to indicate whether or not the liquid departs from Newtonian
behavior. It must be stressed that these checks only lead one to suspect unusual
flow behavior (they are not a replacement for detailed measurements in a
Viscometer).
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
9. In order to describe this behavior quantitatively and to generate data suitable for
engineering design, it is necessary to take measurements in a Viscometer (to
measure the viscous properties of the liquid) or a Rheometer (to measure the full
flow properties or rheology, e.g. elastic properties). The measurement of the
rheology or flow properties in various Viscometer and Rheometers is dealt with
later in this Guide. However, we will initially consider some of the types of nonNewtonian fluid behavior.
4.2
Classification of Non-Newtonian Fluids
In the case of a Newtonian liquid (which is just a special case of the more
general non-Newtonian behavior) it has already been seen that the viscous
stress, Ԏ is directly proportional to the shear rate (velocity gradient),
the viscosity, µ, is the constant of proportionality viz.,
, and
Thus the shear stress is a unique function of the shear rate, given viscosity µ
(which is a material property to be measured in a Viscometer).
There is a class of non-Newtonian liquids called 'time-independent liquids' and
for these materials the shear stress also depends on only the shear rate (but not
in the simple linear form of Equation! 2). That is,
For such materials it is possible to define an apparent viscosity, µa, which is now
dependent upon shear rate
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Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
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10. Thus for time-independent materials, the apparent viscosity changes with shear
rate (it will also vary with temperature and to a lesser extent with pressure). The
material responds instantaneously (for practical purposes) to imposed changes in
shear rate and there is no time-dependency.
In contrast to the above time-independent (i.e. instantaneously responsive) nonNewtonian materials, some liquids exhibit time-dependency and the viscous
properties depend upon the shear rate and the time of shearing, i.e.
Such materials are termed 'time-dependent'.
Finally, there are some industrial liquids which, in addition to viscous properties,
also possess the characteristic of 'elastic solids'. These materials exhibit 'elastic
recovery' after deformation, they possess large 'elongational viscosities' when
stretched and also exert 'normal forces' in steady shearing flows (see Figure 3).
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Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
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11. FIGURE 2 SIMPLE TESTS OF A QUALITATIVE NATURE WHICH INDICATE
WHETHER OR NOT A LIQUID DEPARTS FROM NEWTONIAN BEHAVIOR
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Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
12. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
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Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
13. With a viscoelastic liquid, the shear rate at any instant depends upon the
previous history of the liquid in addition to the current conditions and the
relationship between shear stress and shear rate is very complex.
Non-Newtonian liquids can therefore be classified according to:
(a)
time-independent behavior;
(b)
time-dependent behavior;
(c)
viscoelastic behavior.
In the following sections a more detailed consideration is given to timeindependent liquids since, for such materials, the techniques of quantitatively
describing their viscous flow properties in Viscometers are well established.
Furthermore, the use of such properties in engineering design of pump/pipeline
systems, heat exchangers, mixing vessels, etc. is reasonably well understood.
A briefer discussion is devoted to time-dependent and viscoelastic liquids
because such liquids are difficult to characterize fully in Viscometers and
Rheometers. Furthermore, the incorporation of such data into design procedures
is difficult (and in some cases impossible) with our present state of knowledge.
4.2.1 Time-independent Liquids
These materials can be divided into three types:
Pseudoplastic
liquids
.
Dilatant liquids
-
for which the apparent viscosity, µa, reduces as the
shear rate,
increases
-
for which the apparent viscosity, µa, increases
as the shear rate,
increases.
Bingham plastic
liquids
-
these materials possess a yield stress Ԏy and unless
the shear stresses exceed this value
flow will not commence.
Each type is now considered separately below.
(a)
Pseudoplastic liquids
A typical flow curve, plot of shear stress, Ԏ, vs shear rate,
from a Viscometer for a pseudoplastic liquid is shown in
obtained
Figure 4.
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14. In this Figure it is seen that the apparent viscosity, µa, (defined on the ratio of the
shear stress to shear rate) reduces as the shear rate increases. Such behavior is
also termed 'shear-thinning' and is found in many non-Newtonian liquids.
FIGURE 4
PSEUDOPLASTIC BEHAVIOR
The data can be replotted as apparent viscosity, oa, vs shear rate ˙ and this
clearly shows the reduction in apparent viscosity as the fluid is subjected to
greater and greater velocity gradients (see Figure 5).
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15. FIGURE 5
PSEUDOPLASTIC BEHAVIOR
In some cases it is found that materials which are pseudoplastic at moderate
shear rates tend to Newtonian behavior (i.e. viscosity becomes independent of
shear rate) at low and high values of the shear rate. These limiting viscosities are
often called the zero-shear viscosity, µoo, and the infinite shear viscosity, µo .
This type of behavior is illustrated in Figure 6.
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16. FIGURE 6
(b)
LIQUIDS WITH ZERO AND INFINITE SHEAR VISCOSITIES
Dilatant liquids
The term dilatant indicates that the material increases in apparent viscosity as
the shear rate increases. Such behaviour is often termed shear-thickening. A
typical flow curve is shown in Figure 7 as a plot of shear stress vs shear rate and
also apparent viscosity vs shear rate.
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17. FIGURE 7
DILATANT BEHAVIOR
This type of behavior is less common than shear-thinning (pseudoplastic)
behavior and such materials will present processing difficulties since the more we
try to shear the material, the greater is the resistance offered by the fluid.
(c)
Bingham plastic liquids
In the case of such materials it is not possible to set up velocity gradients (shear
rates) in the fluid until a finite stress, the yield stress, Ԏy, is exceeded. A typical
flow curve for such materials is shown in Figure 8.
FIGURE 8
LIQUID HAVING A YIELD STRESS
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18. The precise value of the yield stress, Ԏy, is often difficult to obtain because its
evaluation requires the extrapolation of viscometric data down to a shear rate of
zero. Indeed, there is much controversy over the existence of 'yield stresses'.
However, the need for an accurate value of the yield stress, Ԏy, is only important
in very low shear rate processes. At moderate and high shear rates the precise
value of the yield stress becomes less important.
All the above materials which are time-independent should respond essentially
instantaneously to imposed changes of shear rate or shear stress and this should
be apparent in obtaining Viscometer data at a variety of shear rates. If the
response to changes in shear rate is finite and significant the material should be
treated as being time-dependent.
4.2.2 Time-dependent Liquids
In the case of liquids which are classed as being time-dependent, the apparent
viscosity depends not only upon the current value of the shear rate but upon the
previous shear rate history to which the liquid has been subjected. If such a liquid
is rested for a long time and then subjected to a steady constant shear rate, two
modes of behaviour are possible. In the case of thixotropic materials the
apparent viscosity reduces with time whereas anti-thixotropic (sometimes called
rheopectic) material exhibits an increase in viscosity with time (see Figure 9).
FIGURE 9
TIME-DEPENDENT LIQUID BEHAVIOR
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19. In both cases, i.e. thixotropic and rheopectic, after shearing at constant rate for a
long time, the apparent viscosity approaches an equilibrium viscosity.
If a time-dependent material is sheared to an equilibrium apparent viscosity at a
given shear rate and then the stress is removed, the apparent viscosity will
gradually increase in the case of the thixotropic fluid and reduce for the antithixotropic fluid. The rates at which viscosities are reduced or increased are not
necessarily the same. For example, for thixotropic liquids, the rate at which the
viscosity is reduced by shearing is often much faster than the recovery under
zero or low shear rate conditions.
Time-dependent materials are difficult to characterise in a Viscometer because
merely putting the material into a Viscometer imposes a shear history upon the
fluid. Furthermore the necessity to obtain dynamic data (i.e. variation in apparent
viscosity with time) requires an instrument with rapid response characteristics.
However, with care relevant Viscometer data can be collected and used in
design and further details are given in Clause 6. At least, Viscometer data will
indicate the worst possible state of the material to be handled and a
conservative design will always result.
It should be noted that thixotropy is the most common type of time-dependent
behavior.
4.2.3 Viscoelastic Fluids
In steady flows in channels of constant cross section the viscoelastic fluid exerts
normal forces, see Figure 3 (c), perpendicular to the shearing motion and
information on such forces can be obtained from Viscometers with normal force
measuring facilities. In other respects in such steady flows, the effects of
elasticity are not detected.
However, in steady flows through channels of varying cross-sections, e.g.
expansions, contractions, valves, orifice plates and in unsteady flows e.g. startup of a pipe-line or in a pulsating flow, the elastic properties of the material can
become very important. In order to obtain relevant data, Viscometers with
oscillatory shearing features can be used. Also extensional Rheometers, jet
thrust Rheometers can be used. More details are given in Clause 7.
Unfortunately, at the present time, data on the rheology of viscoelastic liquids can
only be obtained from Viscometers and Rheometers in very idealised flow
situations. The use of such data for more realistic flows of engineering
significance is still at the forefront of research.
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20. Reliable, general design techniques to handle such fluids have not yet been
developed.
4.3
Caution
(a)
In the preceding treatment of the general characteristics of non-Newtonian
flow behavior, the major characteristics have been isolated and discussed
separately. However, one fluid may exhibit different aspects of nonNewtonian behaviour at the same time or at different shear rates. Thus
one type of behaviour does not preclude other types. For such complex
fluids a knowledge of the processing conditions may enable one to
determine the particular characteristics relevant to that process and often
only one type of non-Newtonian behaviour will determine the flow.
(b)
Much of the literature concerned with rheology is aimed at the prediction
of non-Newtonian characteristics from molecular structure or material
morphology. This is not a reliable approach and rheological data for
engineering design must be obtained by carefully planned Viscometer
experiments. These tests should be carried out over a range of shear
rates relevant to the equipment to be designed (and at appropriate
operating temperatures).
Table 2 gives a rough guide of the type of behavior expected from
different industrial materials. This should be treated with caution. There is
no replacement for careful viscometry to establish rheological
characteristics. It is dangerous to have too many preconceived ideas.
(c)
The selection of the most appropriate type of Viscometer or rheometer is
important. The operating characteristics and the suitability of the most
common types are discussed in Clause 5, 7 and 8.
(d)
Viscometer measurements should always be taken under laminar flow
conditions when the flow is dominated by viscous forces. This is
appropriate since in many cases the high apparent viscosities of nonNewtonian liquids means that they are processed under laminar
conditions. However, there are some instances, e.g. in slurry
transportation in large pipelines, when turbulent flow can be achieved. In
such cases the use of laminar Viscometer data is open to doubt and it
may be that some scale-up from a small pilot plant, operating in turbulent
flow, is the best way to proceed.
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21. TABLE 2
SOME EXAMPLES OF NON-NEWTONIAN MATERIALS
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22. 5
VISCOMETER MEASUREMENTS FOR TIME-INDEPENDENT FLUIDS
Design methods are generally only available for time-independent fluids. It is
possible to carry out some design calculations for thixotropic or viscoelastic fluids
but the procedures are usually very complex and require specialist knowledge.
For time-independent fluids the measurement and data handling procedures are
quite straightforward. Even the pitfalls of the subject are quite well documented.
This section describes the measurement procedures for several Viscometer
geometries together with the standard data processing techniques. The
characteristics of each type of Viscometer are also listed. It concludes with
advice on checking for consistency of the data and their interpretation and on
how to estimate the process shear rate for typical process conditions.
The equations applicable to each type of Viscometer are given in Appendix A.
5.1
Concentric Cylinder Viscometers
A concentric cylinder Viscometer is shown diagrammatically in Figure10. Its main
characteristics are summarized in Table 3. Concentric cylinder Viscometers are
thus suitable for low to moderate viscosity measurements. High viscosities may
be determined in small diameter concentric cylinder Viscometers. Temperature
control is good.
Errors may arise from possible end effects or wall slip, see 5.5.1.
TABLE 3
SUMMARY OF CHARACTERISTICS OF CONCENTRIC
CYLINDER VISCOMETERS
Viscosity Range
-
Low to Moderate
Shear Rate
-
Low to Moderate
Temperature Control
-
Good
Difficulties
-
End Effects
Wall Slip
Turbulence
High Viscosities
-
Require Small Cylinders
High Shear Rates
-
Require (i) Narrow Gap
and/or (ii) Annular Gap.
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23. FIGURE 10 CO-AXIAL OR CONCENTRIC CYLINDER VISCOMETER
5.2
Cone and Plate Viscometers
A cone and plate Viscometer is shown diagrammatically in Figure! 11. The main
characteristics are summarised in Table 4 and are therefore suitable for
moderate to high viscosity measurements. Low viscosities can be measured if
the Viscometer has large cones and small angles. Good temperature control can
be difficult.
FIGURE 11
CONE AND PLATE GEOMETRY
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24. TABLE 4
SUMMARY OF CHARACTERISTICS OF CONE AND PLATE
VISCOMETERS
Viscosity Range
-
Moderate to High
Shear Rate Range
-
Moderate to High
Temperature Control
-
Can be Difficult
Difficulties
-
Relative Cone-Plate Location
Restrictions
-
Gap Angle must be less than 4°
Low Viscosities
-
Require
(i) Small Gap Angles
and/or
(ii) Large Cones
Low Shear Rates
5.3
-
Require Large Gap Angles.
Parallel Plate Viscometer
The parallel plate Viscometer is similar to the cone and plate geometry but does
not have uniform shear rates. Its main application is in determining normal force
data in studies of viscoelastic fluids.
5.4
Tube or Capillary Viscometer
A tube (or capillary) Viscometer is shown diagrammatically in Figure 12. Its main
characteristics are summarized in Table 5. Tube Viscometers are thus suitable
for moderate to high viscosities although low viscosities can be measured using
small diameter tubes. Temperature control is good, but relatively large samples
are required.
Errors may arise from wall slip and end effects.
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25. TABLE 5
SUMMARY OF CHARACTERISTICS OF TUBE OR CAPILLARY
VISCOMETERS
Viscosity Range
-
Moderate to High
Temperature Control
–
Good
Difficulties
-
(i) Relatively Large Sample Required
Shear Rate Range
(ii) End Effects
(iii) Wall Slip
Low Viscosities
-
Require Small Diameter Tubes.
FIGURE 12 TUBE OR CAPILLARY VISCOMETER
5.5
Checks for Consistency of Data and Interpretation
Errors can arise from shortcomings either in the data themselves or in the way
they have been interpreted. Table 6 summarizes consistency checks for different
Viscometer data and their likely causes.
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26. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
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27. 5.5.1 Coaxial Cylinder Viscometers
Equation (23) provides for appropriate data interpretation for non-Newtonian flow
properties. Consequently data for two cylinder combinations of different Ri /Ro
ratio should give the same
Ԏ vs ˙
relationship. If this is not the case there may be a problem of wall
slip (see Note). If this is the case considerable extra data will be needed to allow
for a proper interpretation. At least three inner cylinder diameters should be used
to collect shear stress-speed data. This data can be processed by the procedure
of Oldroyd [Ref. 1] to determine slip velocity and bulk rheology values.
Note:
True wall slip, i.e. a finite wall velocity, is a rare phenomenon e.g. it can occur in
some flows of polymer melts. More usually, wall slip refers to the formation of a
low viscosity layer of liquid next to a solid surface. For example, when slurries
are sheared, particles migrate away from the solid surface leaving a low
viscosity, particle-free layer.
This is not uncommon, especially for non-Newtonian slurries, and care must be
taken to check for unusually low results from such measurements. Standard
measuring systems are sometimes unable to cope with difficult solid dispersions
due either to 'jamming' of the relatively small gaps, excessive wall slip caused by
migration of the dispersed phase away from the sensing member or rapid
sedimentation of the dispersed phase. One practical solution is to replace the
standard sensing member by a miniature agitator which minimises these
problems. After characterising the agitator it can be used to measure torque,
shear stress and viscosity in the usual manner. [Ref 6]
5.5.2 Tubular Viscometers
Equation (6) is necessary for the processing of non-Newtonian flow data to give a
value of shear rate at the tube wall.
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28. If data are available for more than one tube diameter the Ԏ(R) vs
relationship should be the same in all cases. If this is not so the data should be
reprocessed by the procedure of Mooney [Ref. 2] to determine the slip velocity
and then bulk properties.
End Effects in Tube Viscometers
Tube Viscometers are subject to additional pressure losses as the test fluid
enters the tube. This effect can be eliminated by using several tubes of different
length but the same diameter and then determining values of ΔP/L for various
values of Q from plots of ΔP vs L (see Figure 13).
FIGURE 13 DETERMINATION OF END EFFECTS IN TUBE VISCOMETERS
Data of this form are conveniently collected with mechanically driven (Instron,
etc.) tube Viscometers. With pressure driven Viscometers, a cross plot of ΔP vs
Q data may be necessary (see Figure 14).
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29. FIGURE 14 DERIVATION OF END EFFECTS FOR PRESSURE DRIVEN
TUBE VISCOMETERS
In attempting to eliminate end effects, problems may be encountered if the fluid
has thixotropic properties. If the data processing procedure above does not seem
to be satisfactory a check should be made using a rotational Viscometer (either
cone and plate or coaxial cylinder) to check for stress variation with time at
constant rotational speed:
FIGURE 15 TYPICAL DATA FOR THIXOTROPIC FLUIDS
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30. In the early stages of a project it is more convenient to study thixotropic
properties in a rotational Viscometer. Further details are given in Clause 6.
5.5.3 Viscoelasticity
The viscoelastic character of the test fluid may make itself apparent by 'die swell'
in the extrudate from the tube Viscometer. There is no particular procedure which
can be used to improve data processing to allow for this characteristic but it is
wise to record the observation as viscoelasticity since it may be important in
understanding any potential flow problems. It is not a simple matter to collect and
use viscoelastic data for process design, and quality control is about the most
ambitious objective than can be secured by measurements of viscoelasticity.
Further details on appropriate Viscometer techniques for the assessment of
viscoelasticity are given in Clause 7.
5.6
Estimate of Process Shear Rate
Experimental data, from Viscometers cover only a finite range of shear rates. It is
therefore important that this range of shear rates should cover the shear rates
encountered in process for which the data are to be used. Extrapolation or
Viscometer data outside its range of validity is extremely dangerous. Methods for
estimating the process shear rate for typical processconditions are given below.
5.6.1 Steady Laminar Pipe Flow
In steady laminar pipe flow the nominal wall shear rate (i.e.wall shear rate for a
Newtonian fluid in the same pipe at the seam mean velocity) is 8V/D where V is
mean velocity, and D is the pipe diameter.
It is reasonable therefore to obtain Viscometer data over a range of shear rates
around this nominal value.
Although the shear rate at the pipe centre is zero, Sheffield and Metzner [Ref. 3]
have shown that data much below the nominal shear rate do not greatly affect
the flow.
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31. 5.6.2 Turbulent Pipe Flow
In turbulent pipe flow the wall shear rate is high and it is the apparent viscosity of
the fluid at this shear rate which is important. The calculation of the wall shear
rates is one of trial and error [Ref. 4].
5.6.3 Laminar Flow in Mixing Vessel
In a mixing vessel operating under laminar conditions the average shear rate ẏA
in the vessel can be estimated from:
ẏA = ҜsN
………….
(7)
where Ҝs = shear rate constant for impeller. 'Best' current values are given
below:
for
propellers
10
disc or flat-bladded turbines
11.5
angled blade turbines
13
anchors [Ref. 7]
33 - 172(C/dT)
helical ribbon-screw [Ref. 8]
60 (S/dR)0.65
Thus knowing the impeller speed N, the appropriate Viscometer range should be
around the value of ẏA given above.
5.6.4 Turbulent Flow in Mixing Vessel
In a mixing vessel in which the flow is turbulent, the flow is no longer dominated
by viscous forces and the precise shear rate is not too important. It is
Recommended that the previous equations (for laminar mixing) are used here.
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32. 6
MODEL FITTING TO FLOW CURVES
Many design calculations can be conducted using rheological data expressed in
the form of a simple mathematical model - usually shear stress related to shear
rate. Obviously the model can be no more accurate than the data to which it is
fitted and common sense must be used in selecting appropriate models. There
are a variety of simple models to use which relate specific circumstances.
6.1
Power Law
The power law model is frequently applied to the description of shear-thinning or
pseudoplastic flow properties. The form of the equation is:
where K is referred to as the consistency index and n as the flow behaviour
index. The consistency index gives some indication of the viscous resistance
offered to flow and the flow behaviour index gives an indication of the degree of
non-Newtonian behaviour of the fluid. The value of K often changes with
temperature or solids concentration; n is virtually independent of temperature but
may be affected by changes in particle size or form. The value of n lies
between 0 and 1 for shear-thinning fluids. The further away from a value of 1 the
more non-Newtonian is the fluid character.
A log-log plot of shear stress-shear rate data will show if the power law model is
applicable (see Figure 16). In this plot many fluids show an extensive range of
shear rate over which the power law will apply. However in the low shear rate
range it is likely that a degree of Newtonian behaviour will be observed and there
will be differences in slope observed in various regions of the plot.
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33. FIGURE 16 APPLICATION OF POWER LAW
Similar slope changes may be observed at high shear rate. The power law
description may be used in design calculations if the shear rates are known to lie
within the power law region or may subsequently be shown to lie in this region.
The power law parameters may be determined from the slope (n) and the
extrapolated intercept, K at t = 1.
The power law model may also be used to describe the less common property of
dilatancy or shear-thickening. For these fluids the value of the flow behaviour
index (n) will be greater than 1.0, once again the departure from a value of unity
is an indication of the degree of non-Newtonian behavior. The value of K is again
an indication of resistance to flow. However, the comparison of values of K only
has real meaning where fluids have similar values of n. (This restriction applies to
both shear-thinning and shear-thickening fluids.)
6.2
Bingham Plastic
The Bingham Plastic model is used to describe shear-thinning fluids which have
a yield stress. The form of the equation is:
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34. where the yield stress, ty, is the stress value which must be exceeded before
shear commences. The term, µp, plastic viscosity, is a parameter and not to be
Confused with the usual meaning of viscosity except when µp > ty.
A linear plot of shear stress/shear rate data as illustrated in Figure 17 will show if
the Bingham plastic model is applicable.
FIGURE 17 TYPICAL IDEAL BINGHAM PLASTIC BEHAVIOR
Many fluids give a plot of this kind, particularly for narrow ranges of shear rate. It
is important that linearity in such a case should not be regarded as justification
for an assumed yield stress by extrapolation, particularly if that extrapolation is
over a significant range of shear rate. If an understanding of the yield stress is
important to a particular exercise, it is desirable that data at low shear rate should
be available to improve the accuracy of the extrapolation.
It is frequently found that such plots are not entirely linear, both at low shear
rates and elsewhere. Figure 18 is such an example.
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35. FIGURE 18 NON-LINEAR BINGHAM PLASTIC BEHAVIOR
In such cases extrapolation is more difficult but a modified Bingham model,
Herschel-Bulkley or generalised Bingham, can be used. This is expressed as:
The parameters Kp and n can be determined in a manner analogous to that used
for power law fluids by plotting log (tx - ty) vs log ẏ The intercept at ẏ = 1 gives a
value of Kp and the slope gives the value of n (usually n < 1). It may be
necessary to establish the best relationship bytrial and error, estimating various
rates of ty then Kp and ẏ to lead to a plot of t vs ẏ giving best least squares fit.
6.3
Direct use of Numerical Data
The use of mathematical models to describe the shear stress-shear rate
behaviour of non-Newtonian liquids has appeal, particularly if the form of
equation is amenable to subsequent mathematical manipulation, e.g. to evaluate
flow rate-pressure drop relationships. Also the use of models permits
extrapolation of the data, but this can be very dangerous when taken too far
and the use of a mathematical model (once adopted) can hide this extrapolation.
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36. In many cases it is found that the viscometric data do not fit conveniently any of
the simple models often used, e.g. power law or Bingham plastic. However, this
is often not serious because the numerical data together with interpolation
methods can often be incorporated directly into design procedures thus
eliminating the model fitting stage. This procedure has the added advantage that
checks can continuously be made to examine whether or not the data are
to be extrapolated.
6.4
Rheological Models Involving Temperature Dependence
Most non-Newtonian liquids exhibit viscous properties which are highly
dependent upon temperature; as the temperature increases the viscosity usually
decreases (although a few complex materials act in the opposite way). It should
be remembered at all times that these variations in viscosity due to temperature
changes can often be more dramatic than the non-Newtonian changes in
apparent viscosity due to changes in shear rate.
This has two major implications:
(a)
Careful temperature control should be exercised in all Viscometer tests
and the temperature should be matched accurately to the process
temperature.
(b)
In heat transfer operations the variation in viscosity with temperature in the
equipment will be of significance in design and rheological data should be
collected over the appropriate range of temperatures.
In order to collect rheological data over a range of temperatures for timeindependent materials, measurements are taken of shear stress against shear
rate at a variety of temperatures (see!Figure! 19).
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37. FIGURE 19 EFFECT OF TEMPERATURE
In many cases this data can be fed into a computer store and used directly in
design procedures, the appropriate process viscosity being obtained from the
test data by means of an interpolation method for the process shear rate and
temperature.
In some instances it is helpful to use a model of the temperature and shear rate
dependence of apparent viscosity and this can then be used to evaluate oa
under the appropriate processing conditions. This has the advantage that if the
model is physically realistic, extrapolation of the data outside the test range of
shear rate and/or temperature is feasible.
Two approaches are commonly used. The first is based on the Arrhenius
equation developed for Newtonian fluids, i.e.
where A and a are constants independent of temperature.
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38. The equivalent form based on the power law equation is:
And this is rewritten as:
all of which can be found from viscometric tests over a range of temperatures.
If the material is found to have a significant yield stress, ty, the above equation
can be modified to give:
A second approach is based upon an alternative to the Arrhenius equation, i.e.
where µ1 is the viscosity at reference temperature T1 and β1 is a parameter,
independent of temperature. The power law modification to the form is:
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39. and again these parameters can be obtained from Viscometer data covering an
appropriate range of shear rates and temperatures. As before, if the material has
a significant yield stress the equation becomes:
Equations (14) and (17) are the form:
A third approach convenient for numerical analysis evaluates the function F(T) as
a polynomial in T, e.g.
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40. 7
CHARACTERIZATION OF TIME-DEPENDENT LIQUIDS
In this section a brief description is given of some of the ways of determining
useful rheological data for time-dependent non-Newtonian liquids. Emphasis is
placed upon relatively simple procedures which will generate quantitative data
which can be used for engineering design purposes. Also the measurements will
give some idea as to the way in which such materials should be efficiently
processed e.g. it is advisable with thixotropic liquids which build up a
structure (and hence a high apparent viscosity) at very low shear rates or on
standing, to keep the material subjected to high shear rates at all times. Stopping
the process will produce a high viscosity liquid which could give severe start-up
problems.
The tests described below for time-dependency are best carried out in rotational
Viscometers, preferably in a co-axial cylinder device. Severe problems arise in
interpreting data from capillary Viscometers for time-dependent liquids.
In many cases it is often not necessary to know the complete rheological
characterisation of the liquid - indeed this is a research project in its own right for
many materials. However, the procedures outlined below will give useful data on
the material in its worst state and under normal steady state operating conditions.
7.1
Sample Loading
The viscous properties of a time-dependent liquid depend upon the previous
shearing to which the material has been subjected. This creates an immediate
problem for characterization in a Viscometer because the act of loading the
sample into the instrument creates a shearing action.
In order to load the Viscometer with a sample, and to achieve a reproducible test
procedure, it is recommended that the liquid is put into the Viscometer and then
sheared in the device at a constant shear rate until the shear stress reading it
becomes essentially constant (i.e. it has reached its equilibrium value, see 4.2).
Care must be taken in choosing the shear rate, since it is possible to destroy a
very large part of the rheological structure. This effect can be used to advantage
as a measurement technique by breaking the structure initially and then reducing
the shear rate; provided that the material recovers in a practicable time. The
material can then be used directly for characterisation at other shear rates or
alternatively the sample can be allowed to rest for a fixed time before the start of
the characterisation. This latter procedure permits good thermostatting of the
sample for cases where the test temperature is important.
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41. 7.2
Tests at Constant Shear Rate
After the sample has been loaded into the Viscometer, sheared to equilibrium
and then rested, as described in the previous Clause, the extent of the material's
time-dependency can be assessed. This is done by setting the Viscometer at a
constant shear rate,
and observing the change in the measured shear
apparent viscosity, µa), see Figure 20.
stress, Ԏ, (or
FIGURE 20 TYPICAL CONSTANT SHEAR RATE DATA
This process can be repeated (including loading each time) at a variety of shear
rates relevant to the actual processing conditions and the extent of the timedependency can be assessed by comparing the initial and equilibrium stresses or
apparent viscosities. Also data presented in this way give a measure of the rate
at which structure is either broken down or built up under shearing conditions.
In deciding whether or not the changes from Ԏ1 to Ԏeq (or µ1 to µeq) are
significant, the importance of the viscous properties in the actual process and the
accuracy of the design equations to be used must be assessed. However, as a
rule of thumb, changes of less than 10% in stress or viscosity with time under
constant shear rate conditions indicate that timedependency can be ignored for
design purposes. Changes of about 30% or more should certainly be allowed for.
If the actual process is one of approximately constant shear rate, then the curves
above indicate the extremes of behaviour of the liquid which can be encountered.
For example, for a thixotropic liquid the apparent viscosity of the rested sample is
the highest likely value and its use in design will be conservative.
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42. 7.3
Dynamic Response Measurement
When interpreting the significance of the measurements of time-dependency
obtained from rotational Viscometers at constant shear rate, it should be
remembered at all times that the material is also shear rate dependent. For
example, if we take a sample which has been subjected to shear rate ẏ1 for time
t1 in the Viscometer, at the time Ԏ1 the material is shear dependent and sudden
changes in shear rate will bring instantaneous responses in apparent viscosity,
as well as the longer term time-dependent effect shown above.
Consider the case of a thixotropic liquid which is sheared at ẏ1 for time Ԏ1, see
Figure 21.
FIGURE 21 DYNAMIC RESPONSE DATA
If the Viscometer is quickly changed to a series of new shear rates ẏa, ẏb, ẏc, etc.
the non-Newtonian (in this case, shear-thinning response) will be revealed, i.e.
we observe that the apparent viscosity is dependent upon shear rate. This test
needs to be conducted rapidly so that the longer term time-dependent effects of
shearing are eliminated. Of course, this calls for an instrument with a good
dynamic response, otherwise the measurements reflect the mechanical
responses of the instrument to rapidly imposed speed changes.
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43. 7.4
Changes in Shear Rate
In some cases it is important to know how the material will behave if it is
subjected to changes in shear rate. In such instances relevant Viscometer data
can be obtained by subjecting a sample to one shear rate, ẏ1 for a period of time
Ԏ1 and then changing the shear rate instantaneously to a new value ẏ2, see
Figure 22.
FIGURE 22 CHANGE IN SHEAR RATE DATA
Here the case is illustrated of a thixotropic liquid which is subjected to a decrease
in shear rate from ẏ1 to ẏ2 at time t1. At time t1 the instantaneous change in
shear rate brings about the initial dynamic response giving a lower stress and
higher apparent viscosity because the shear rate is lowered and it is assumed
that the material is shear-thinning. After time t1 a recovery of viscosity is
observed. It is worthy of note that the rate of breakdown of viscosity under shear
is not necessarily the same as the rate of recovery. Often it is found that
breakdown is a much more rapid process than recovery but this is not
necessarily so in all cases.
Other possible forms of response to imposed shear rate changes in the
Viscometer are shown in Figure 23. In these Figures the rapid initial dynamic
response to changes in shear rate has been neglected and the curves drawn are
typical of the responses obtained from a Viscometer with a poor dynamic
response to imposed speed changes.
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44. Using the Viscometer in this way the response of time-dependent materials to
changes in the process shear rate can be modelled.
FIGURE 23 OTHER FORMS OF RESPONSE TO CHANGES IN SHEAR RATE
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45. 7.5
Concluding Remarks
The detailed study of the rheology of time-dependent non-Newtonian liquids is a
complex topic. However, in this Guide relatively simple tests have been outlined
which enable measurements to be taken which are useful in design.
(a)
A procedure for loading the Viscometer to obtain reproducible results is
presented.
(b)
Simple steady shear rate tests allow the reader to assess whether or not
the material is significantly time-dependent. If it is, such experiments allow
an assessment to be made of the best and worst possible states of the
material during processing.
(c)
Dynamic response tests are outlined which indicate the shear rate
dependency of the apparent viscosity. Such tests should be carried out
rapidly and require an instrument with a good dynamic response to speed
changes.
(d)
Tests are outlined which permit Viscometer data to be obtained in a way
which will model shear rate changes experienced during processing.
8
TECHNIQUES FOR CHARACTERISATION OF VISCOELASTIC
LIQUIDS
There are a number of commercial Rheometers which allow some
measurements to be made of viscoelastic properties. In almost all cases it is
difficult to either interpret or apply the measurements made. The most immediate
use that can be made of such measurements is in quality control problems.
There are a number of different types of measurement that can be made and
these are:
8.1
Stress Relaxation
This is probably the least demanding experiment in terms of the instrumentation
required and so is relatively inexpensive. After a known shear history, shearing is
stopped and the stress-time (decay) process recorded.
Measurements of strain relaxation can also be made with some instruments and
it may be possible to convert some stress relaxation measurements to strain.
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46. 8.2
Oscillatory Shear Measurements
This test facility is available on a number of instruments. Measurements may be
carried out at a range of frequencies and amplitudes, usually in rotational
Viscometers using cone and plate geometry. The data collected are usually more
tractable if small amplitudes are used (usually referred to as the 'linear' range).
The data collected are usually in the form of amplitude ratio (output
displacement, input displacement) and phase angle (output relative to input
displacement). If the fluid tested is inelastic the input and output displacement will
have a phase angle of 90°. For fluids having elastic properties the phase angle
will be less than 90° and viscosity and elastic moduli can be calculated from the
components of the output displacement in phase and out of phase with the input
amplitude. These two moduli are usually plotted as functions of frequency.
8.3
Normal Force Measurement
Facilities for this measurement are available to varying degrees of sophistication
in several rotational Viscometers. In this experiment, the elasticity of the test fluid
manifests itself as a force tending to separate cone and plate or plate and plate
in steady shear experiments. The data from these two types of experiment can
be used to determine first and second normal force differences respectively, both
as functions of shear rate.
8.4
Elongational Viscosity Measurement
Experiments to determine elongational viscosity can be conducted in a number of
ways. One of the most convenient in terms of experimental accuracy is the
suspended siphon test. For many viscoelastic fluids it is possible to establish an
open siphon in which a stream of liquid is lifted from a reservoir to a tube by
virtue of its axial tensile strength. By using measurements of the weight of the
suspended thread of liquid, the liquid flow rate and the shape of the thread
(photographs) elongational viscosity may be determined as a function of
extension rate.
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47. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
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48. 10 BIBLIOGRAPHY
Ref
Source
[1]
W L Wilkinson, 'Non-Newtonian Fluids', Pergamon, New York,
1960.
[2]
K Walters, 'Rheometry', Chapman & Hall, 1975.
[3]
G Astarita et al (eds), 'Rheology' Vol. 1, 2, Plenum Press, 1980.
[4]
R I Tanner, 'Engineering Rheology', Clarendon Press, Oxford,
1985.
[5]
H A Barnes, J F Hutton, & K Walters 'An Introduction to Rheology',
Elsevier, 1989.
[6]
K J Carpenter, T E Heald, 'Derivation of Rheological Data from
Non-Standard Sensors on the Haake Rotovisco Viscometer'
[7]
P A Shamlov, M F Edwards, 'Power Consumption of Anchor
Impellers in Newtonian and Non-Newtonian Liquids' Chem. Eng.
Res. Des., Vol 67, Sept 1989.
[8]
L Choplin, T Merquinol, 'Mixing of Viscoelastic Fermentation Broth
with Helical Ribbon-Screw (HRS) Impeller' 6th European
Conference on Mixing, Pavia, Italy 1988.
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49. APPENDIX A
A.1
EQUATIONS FOR VISCOMETERS
EQUATIONS FOR CONCENTRIC CYLINDER VISCOMETERS
A.1.1 Equations for Newtonian Fluids
Newtonian Fluids
The level of viscous drag at any time is described in terms of force per unit area,
the shear stress, Ԏ.
Viscous drag is a function of the number of intermolecular collisions occurring per
unit time, this being described in terms of velocity gradient or shear rate, ẏ.
For Newtonian fluids the shear stress-shear rate relationship is adequately
described by the viscosity which is constant at constant temperature (and
pressure).
Viscosity = Ԏ /ẏ
=µ
Note that the calculation of the shear rate is only valid for Newtonian fluids.
No allowance for the influence of end effects is included. For discussion of this,
refer to 5.5.2
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50. A.1.2 Standard Equations for non-Newtonian Fluids
The shear stress, Ԏ, may be calculated as for Newtonian fluids, but the shear
rate requires a calculation procedure based on the data collected over a range of
speeds.
(a)
Plot the torque-speed data on log-log coordinates as shown in Figure 24
(where the data result in a linear plot) or Figure 24 (b) (where a non-linear
plot results).
FIGURE 24 TORQUE SPEED PLOTS
(b) Calculate the shear rate ẏ as follows:
case (i) for linear plot
ẏ
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51. where np is the slope of the linear log-log plot
case (ii) for non-linear plots
ẏ
where np is the slope of the log T vs log N plot at each value of N. As np varies
with N, the appropriate value must be applied for each value of N used in the
calculation.
The procedure is only valid if (ln s)/np < 0.5, which is generally the case for
commercial Viscometers. A more cumbersome calculation procedure is required
if this is not the case.
This procedure can also be applied to the frequently encountered pseudoplastic
or shearthinning fluids and the less common dilatant or shear-thickening fluids.
A.1.3 Calculation for Bingham Plastic Fluids
For Bingham plastic fluids which give a linear plot of torque against speed, as
illustrated in Figure 25, the Newtonian relationship for shear rate:
may be used.
However, if the plot is not linear the data should be re-examined as for A.1.2(b),
case (i) and (ii) using a log T vs log N plot. It is most likely that case (ii) will apply
(non constant value of np) and shear rate may be calculated in the same way,
remembering the restriction
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52. FIGURE 25 TORQUE vs SPEED PLOT FOR BINGHAM PLASTICS
A.2 EQUATIONS FOR CONE AND PLATE VISCOMETERS
Provided the gap angle (θc) is less than 4°, the shear rate can be calculated from
the angle and speed alone and the equations are valid for both Newtonian and
non-Newtonian fluids.
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53. A.3
EQUATIONS FOR PARALLEL PLATE VISCOMETER
The shear stress at radius R is given by:
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54. A.4
EQUATIONS FOR TUBE OR CAPILLARY VISCOMETERS
For Newtonian and non-Newtonian fluids, the shear stress and shear rate vary
with radial position in the tube. The values are therefore usually calculated at the
tube wall as follows:
Shear stress at the wall
The bracketed term in Equation 31(b) is called the Rabinowitsch correction.
Since m can be as low as 0.2, this correction can be highly significant in
determining the true wall shear rate.
If this plot is not linear, a value of m must be taken for each value of Q.
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55. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
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