The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...Gerard B. Hawkins
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed Tubular Reactor
CONTENTS
0 INTRODUCTION
1 n-BUTANE OXIDATION
2 REACTION KINETICS
3 HEAT AND MASS TRANSFER PARAMETERS
4 NON-ISOTHERMAL, NON-ADIABATIC REACTOR MODELING
5 USE OF THE REACTOR MODEL IN OPERABILITY AND DESIGN STUDIES
6 BIBLIOGRAPHY
7 NOMENCLATURE
Filtration
0 INTRODUCTION
1 The Theory Underlying Filtration Processes
1.1 The Mechanism of Simple Filtration Systems
1.1.2 Cake Filtration
1.1.3 Complete Blocking
1.1.4 Standard Blocking
1.1.5 Intermediate Blocking
1.2 Cake Filtration – Models and Mechanisms
1.2.1 Classical Theory for the Permeability of Porous Cakes and Beds
1.2.2 The Rate of Filtration through a Compressible Cake – The Standard Filtration Equation
1.2.3 The Compression or Consolidation of Filter Cakes – Ultimate degree of dewatering
1.2.4 The Rate of Consolidation
1.2.5 Useful Semi-Empirical Relations for Constant Pressure and Constant Rate Cake Filtration
1.2.6 Constant Pressure Filtration
1.2.7 Constant Rate Filtration
1.2.8 Multiphase Theory of Filtration
1.3 Crossflow Filtration
2 The Range and Selection of Filtration Equipment Technology
2.1 Scale
2.2 Solids Recovery, Liquids Clarification or Feed stream Concentration
2.3 Rate of Sedimentation
2.4 Rate of Cake Formation and Drainage
2.5 Batch vs Continuous Operation
2.6 Solids Loading
2.7 Further Processing
2.8 Aseptic or “Hygienic” Operation
2.9 Miscellaneous
2.10 Shear versus Compressional Deformation
2.11 Pressure versus Vacuum
3 Suspension Conditioning Prior to Filtration
3.1 Simple Filtration Aids
3.2 Mechanical Treatments
4 Post-Filtration Treatments and Further Downstream Processing
4.1 Washing
4.1.1 Air-Blowing
4.1.2 Drying
5 Testing and Characterization of Suspensions
5.1 Introduction – Suspension
5.2 Properties relevant to Filtration Performance
5.2.1 Pre-Filtration Properties of Suspension
5.2.2 Properties of Filter Cake
5.2.3 Laboratory Scale Filtration Rigs
5.3 Means of Monitoring Flocculant Dosage
5.4 Filter Cake Testing
5.4.1 Strength Testing (See also piston press described earlier)
5.4.2 Cake Permeability or Resistance
5.4.3 Rate of Cake Formation
6 Examples of the Application of the Forgoing Principles
6.1 Dewatering of Calcium Carbonate Slurries
6.2 Dewatering of Organic Products – Procion Dyestuffs
6.3 Filtration of Biological Systems – Harvesting a Filamentous Organism
References
Tables
Figures
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
H - Acid Caustic Fusion Stage
CONTENTS
0 INTRODUCTION
1 DESIGN INFORMATION
1.1 Reactor Type
1.2 Temperature Range
1.3 Pressure Range
1.4 Chemical System
2 BACKGROUND
3 KINETICS AND MECHANISM
4 MAXIMUM YIELD AND IMPLICATIONS FOR REACTOR DESIGN
5 USE OF DESIGN MODEL FOR START-UP AND MANUFACTURING MONITORING
6 BIBLIOGRAPHY
FIGURES
1 FUSION MODEL OUTLINE MECHANISM AND KINETIC SCHEME
2 TEST RUN OPTIMIZATION OF HEATING TIME 3600 kg/h STEAM
Gas Mixing
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 RECOMMENDATIONS FOR GAS MIXING:
PLUG FLOW
5 RECOMMENDATIONS FOR GAS MIXING:
BACKMIXED INITIAL ZONE
6 BIBLIOGRAPHY
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
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...Gerard B. Hawkins
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed Tubular Reactor
CONTENTS
0 INTRODUCTION
1 n-BUTANE OXIDATION
2 REACTION KINETICS
3 HEAT AND MASS TRANSFER PARAMETERS
4 NON-ISOTHERMAL, NON-ADIABATIC REACTOR MODELING
5 USE OF THE REACTOR MODEL IN OPERABILITY AND DESIGN STUDIES
6 BIBLIOGRAPHY
7 NOMENCLATURE
Filtration
0 INTRODUCTION
1 The Theory Underlying Filtration Processes
1.1 The Mechanism of Simple Filtration Systems
1.1.2 Cake Filtration
1.1.3 Complete Blocking
1.1.4 Standard Blocking
1.1.5 Intermediate Blocking
1.2 Cake Filtration – Models and Mechanisms
1.2.1 Classical Theory for the Permeability of Porous Cakes and Beds
1.2.2 The Rate of Filtration through a Compressible Cake – The Standard Filtration Equation
1.2.3 The Compression or Consolidation of Filter Cakes – Ultimate degree of dewatering
1.2.4 The Rate of Consolidation
1.2.5 Useful Semi-Empirical Relations for Constant Pressure and Constant Rate Cake Filtration
1.2.6 Constant Pressure Filtration
1.2.7 Constant Rate Filtration
1.2.8 Multiphase Theory of Filtration
1.3 Crossflow Filtration
2 The Range and Selection of Filtration Equipment Technology
2.1 Scale
2.2 Solids Recovery, Liquids Clarification or Feed stream Concentration
2.3 Rate of Sedimentation
2.4 Rate of Cake Formation and Drainage
2.5 Batch vs Continuous Operation
2.6 Solids Loading
2.7 Further Processing
2.8 Aseptic or “Hygienic” Operation
2.9 Miscellaneous
2.10 Shear versus Compressional Deformation
2.11 Pressure versus Vacuum
3 Suspension Conditioning Prior to Filtration
3.1 Simple Filtration Aids
3.2 Mechanical Treatments
4 Post-Filtration Treatments and Further Downstream Processing
4.1 Washing
4.1.1 Air-Blowing
4.1.2 Drying
5 Testing and Characterization of Suspensions
5.1 Introduction – Suspension
5.2 Properties relevant to Filtration Performance
5.2.1 Pre-Filtration Properties of Suspension
5.2.2 Properties of Filter Cake
5.2.3 Laboratory Scale Filtration Rigs
5.3 Means of Monitoring Flocculant Dosage
5.4 Filter Cake Testing
5.4.1 Strength Testing (See also piston press described earlier)
5.4.2 Cake Permeability or Resistance
5.4.3 Rate of Cake Formation
6 Examples of the Application of the Forgoing Principles
6.1 Dewatering of Calcium Carbonate Slurries
6.2 Dewatering of Organic Products – Procion Dyestuffs
6.3 Filtration of Biological Systems – Harvesting a Filamentous Organism
References
Tables
Figures
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
H - Acid Caustic Fusion Stage
CONTENTS
0 INTRODUCTION
1 DESIGN INFORMATION
1.1 Reactor Type
1.2 Temperature Range
1.3 Pressure Range
1.4 Chemical System
2 BACKGROUND
3 KINETICS AND MECHANISM
4 MAXIMUM YIELD AND IMPLICATIONS FOR REACTOR DESIGN
5 USE OF DESIGN MODEL FOR START-UP AND MANUFACTURING MONITORING
6 BIBLIOGRAPHY
FIGURES
1 FUSION MODEL OUTLINE MECHANISM AND KINETIC SCHEME
2 TEST RUN OPTIMIZATION OF HEATING TIME 3600 kg/h STEAM
Gas Mixing
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 RECOMMENDATIONS FOR GAS MIXING:
PLUG FLOW
5 RECOMMENDATIONS FOR GAS MIXING:
BACKMIXED INITIAL ZONE
6 BIBLIOGRAPHY
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
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
Fundamentals of Suspensions & Dispersion's
0 INTRODUCTION
1 NATURE OF SURFACE FORCES
2 STABILITY AND THE STATE OF DISPERSION OF
SUSPENDED PARTICLES
3 MECHANISMS OF FLOCCULATION
4 STRUCTURE OF FLOCCULATED SUSPENSIONS
4.1 Dilute Suspensions
4.2 Concentrated Suspensions
5 STRUCTURE OF STABLE SUSPENSIONS OF
MONODISPERSE PARTICULATES
6 SUMMARY OF STRUCTURES
7 PARTICLE PACKING
8 RHEOLOGY
8.1 Basic Rheological Concepts
8.2 Colloidally Stable Suspensions
8.2.1 Spherical Particles of around 1 µm
8.2.2 Effect of Particle Size Distribution
8.2.3 Effect of Particle Shape
8.2.4 Submicron Particles
8.2.5 Very Concentrated Systems
8.3 Rheology of Flocculated / Aggregated Systems
8.3.1 Dilute Flocculated Systems
8.3.2 Concentrated Flocculated Systems
8.3.3 Time and History Effects
8.3.4 Slip and Fracture
8.3.5 Behavior of Flocculated Cakes in Compression
8.4 Summary of Rheology
Deflocculated Suspensions
Flocculated Suspensions
9 SEDIMENTATION OF SMALL PARTICLES
9.1 Very Dilute Particles
9.2 Concentrated Systems
9.3 Polydisperse Systems
9.4 Flocculated Systems
10 ELECTROKINETIC BEHAVIOR
11 A NOTE ON MAKING DISPERSIONS AND SUSPENSIONS
12 References
13 Figures
Fig 1a Potential Energy Diagram for Steric Stabilization
Fig 1b PE Diagram for Electrostatic Stabilization
Fig 1c Combined Stabilization
Fig 2&3 DIFFERENT TYPES OF FLOCCULATION MECHANISM IN WHICH POLYMERIC SPECIES ARE INVOLVED
Fig 4 Rheological Behavior
Fig 5 Relative Viscosity versus Volume Fraction for Polystyrene Spheres in Water
Fig 6 Time Dependent Flow Behavior of Very Concentrated Suspensions
Fig 7 Flow curves for Flocculated Dispersions
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
Turbulent Heat Transfer to Non Newtonian Fluids in Circular TubesGerard B. Hawkins
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 THE INTEGRATION OF THE ENERGY EQUATION
5 THE EDDY VISCOSITY FOR NON-NEWTONIAN AND DRAG REDUCING FLUIDS
6 THE CALCULATION OF HEAT TRANSFER
COEFFICIENTS FOR NON-NEWTONIAN AND DRAG
REDUCING FLUIDS IN TURBULENT PIPE FLOW
6.1 General
6.2 Drag Reducing Fibre Suspensions
6.3 Transition Delay
7 NOMENCLATURE
8 BIBLIOGRAPHY
Overflows and Gravity Drainage Systems
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 OUTLINE OF THE PROBLEM
5 DESIGNING FOR FLOODED FLOW
6 DESIGNING NON-FLOODED PIPELINES
6.1 Vertical Pipework
6.2 From the Side of a Vessel
6.3 Established (uniform) Flow in Near-horizontal Pipes
6.4 Non-uniform Flow
7 NON-FLOODED FLOW IN COMPLEX SYSTEMS
8 ENTRAINING FLOW
9 SIMPLE TANK OVERFLOWS
9.1 Venting of the Tank
10 BIBLIOGRAPHY
11 NOMENCLATURE
TABLE
1 GEOMETRICAL FUNCTIONS OF PART-FULL PIPES
FIGURES
1 TYPICAL SEQUENCE OF SURGING FLOW
2 DESIGNING FOR FLOODED FLOW
3 CAPACITY OF SLOPING PIPELINES
4 OVERFLOW FROM SIDE OF VESSEL
5 METHODS OF AVOIDING LARGE CIRCULAR SIDE
OVERFLOWS
6 CAPACITY OF A GENTLY SLOPING PIPE AS A FUNCTION OF LIQUID DEPTH
7 COMPLEX PIPE SYSTEMS
8 REMOVAL OF ENTRAINED GASES
General Water Treatment For Cooling Water
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 CHOICE OF COOLING SYSTEM
4.1 ‘Once through' Cooling Systems
4.2 Open Evaporative Recirculating Systems
4.3 Closed Recirculating Systems
4.4 Comparison of Cooling Systems
5 MAKE-UP WATER QUALITY
6 FOULING PROCESSES
6.1 Deposition
6.2 Scaling
6.3 Corrosion
6.4 Biological Growth
7 CONTROL OF THE COOLING SYSTEM
7.1 ‘Once through' Cooling Systems
7.2 Closed Recirculating Systems
7.3 Open Evaporative Cooling Systems
TABLES
1 RELATIVE IMPORTANCE OF FOULING PROCESSES AND INSTALLED COSTS
2 WATER QUALITY PARAMETERS
FIGURES
1 PREDICTION OF CALCIUM CARBONATE SCALING
2 CALCIUM SULFATE SOLUBILITY
3 CALCIUM PHOSPHATE SCALING INDEX
Troubleshooting in Distillation Columns
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 FLOW DIAGRAM FOR TROUBLESHOOTING
5 GENERAL APPRAISAL OF PROBLEM
5.1 Is the Problem Real?
5.2 What Is the Magnitude of the Problem?
5.3 Is it the Column or the Associated Equipment which is Causing the Problem?
6 PROBLEMS IN THE COLUMN
6.1 Capacity Problems
6.2 Efficiency Problems
7 PROBLEMS OUTSIDE THE COLUMN
7.1 Effect of Other Units on Column Performance
7.2 Column Control System
7.3 Improper Operating Conditions
7.4 Auxiliary Equipment
8 USEFUL BACKGROUND READING
9 BIBLIOGRAPHY
FIGURES
1 FLOW DIAGRAM FOR TROUBLESHOOTING
2 DETERMINATION OF COLUMN CAPACITY
Determination of Inert Gas in Anhydrous Ammonia
ANHYDROUS AMMONIA: DETERMINATION OF INERT GASES
SCOPE AND FIELD OF APPLICATION
This packed-column GC method is suitable for the determination of hydrogen, nitrogen, oxygen, argon and carbon monoxide in anhydrous ammonia. The determinations of the gases are linear in the range O-100 ppm v/v.
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
Distillation Sequences, Complex Columns and Heat IntegrationGerard B. Hawkins
Distillation Sequences, Complex Columns and Heat Integration
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 SEQUENCING OF SIMPLE COLUMNS
4.1 Sidestream Columns
4.2 Multi-Feed Columns
5 SIMPLE COLUMN SEQUENCING AND HEAT
INTEGRATION INTERACTIONS
5.1 Energy Quantity and Quality
5.2 Heat Integration within the Total Flowsheet
6 COMPLEX COLUMN ARRANGEMENTS
6.1 Indirect Sequence with Vapor Link
6.2 Sidestream Systems
6.3 Pre-Fractionator Systems
7 COMPLEX COLUMNS AND HEAT INTEGRATION
INTERACTIONS
FIGURES
1 DIRECT AND INDIRECT SEQUENCES
2 A SINGLE SIDESTREAM COLUMN REPLACING 2
SIMPLE COLUMNS
3 A TYPICAL MULTI-FEED COLUMN
4 TYPICAL GRAND COMPOSITION CURVE
5 TYPICAL INDIRECT SEQUENCE WITH VAPOUR LINK
6 SIDESTREAM STRIPPER AND SIDESTREAM
RECTIFIER
7 SIMPLEST PRE-FRACTIONATOR SYSTEM
8 SIMPLEST PRE-FRACTIONATOR SYSTEM
9 PETLYUK COLUMN
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
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
Psychrometry
0 INTRODUCTION / PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 PSYCHROMETRIC CHARTS
5 EXAMPLE CALCULATION
6 CHARTS FOR SPECIFIC SYSTEMS
7 BIBLIOGRAPHY
FIGURES
1 GROSVENOR CHART (Humidity vs. Temperature)
FOR AIR-WATER VAPOR AT 1.0133 bar
2 MOLLIER CHART (Enthalpy vs. Humidity) FOR
NITROGEN-TOLUENE VAPOR AT 100 kPa
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
Isothermal Methanol Converter (IMC) UA Distribution AnalysisGerard B. Hawkins
Isothermal Methanol Converter (IMC) UA Distribution Analysis - Case Study: #0630416GB/H; ACME Co. 9,000 MTD MeOH
This converter uses plates instead of tubes to remove the heat from the reaction gas. The use of the plates and the orientation allow the heat transfer within the converter to be more accurately controlled to follow the maximum rate line.
This case study examines the Radial Flow – Isothermal Methanol Converter (IMC) for ACME Co. 9,000 MTD, based on the Casale Isothermal Methanol Converter (IMC) design.
Solid Catalyzed Gas Phase Reactor Selection
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 ADIABATIC REACTORS
4.1 Single Bed Reactors
4.2 Divided Bed Reactors
4.3 Moving Bed Reactors
4.4 Radial Flow Reactors
5 NON ADIABATIC REACTORS
5.1 Tubular Reactor with External Heating/Cooling
5.2 Tube Cooled Reactors
5.3 Autothermal Reactors
5.4 Hot/Cold Shot Reactors
5.5 Divided Bed Reactors with Intercooling
5.6 Radial Flow Reactors with Intercooling
5.7 Fluid Bed Reactors
6 NOTES ON USING REACTOR SELECTION
GUIDE (TABLE 1)
TABLE
1 REACTOR SELECTION GUIDE
FIGURES
1 TUBULAR REACTOR: EXAMPLE OF CATALYST IN ANNULAR TUBES COOLED BY STEAM RAISING
2 AUTOTHERMAL REACTOR: CATALYST BED COOLED BY INFLOWING GAS IN TUBES
3 COLD SHOT CONVERTER: FIXED ADIABATIC BEDS WITH INTERBED QUENCH GAS MIXING
Determination of Residue on Evaporation in Anhydrous AmmoniaGerard B. Hawkins
Determination of Residue on Evaporation in Anhydrous Ammonia
1 SCOPE AND FIELD OF APPLICATION
This method is suitable for the determination of the residue left after evaporation i.e., the non-volatile material in ammonia solution.
2 PRINCIPLE
A known weight of sample is evaporated to dryness in a platinum dish on a steam bath. The increase in mass of the dish is measured.
TEMPERATURE MEASUREMENT:
RESISTANCE ELEMENTS AND THERMOCOUPLES
SPECIFICATION OF FUNCTION
DESCRIPTION OF FLUID
NORMAL OPERATING TEMPERATURE
REQUIRED TEMPERATURE RANGE
ALARM SETTINGS
TRIP SETTINGS
FLUID VELOCITY
REYNOLDS NUMBER
LINE SIZE
LINE REFERENCE
EQUIPMENT REFERENCE
NOZZLE SIZE
MINIMUM DESIGN PRESSURE
CORRESPONDING TEMPERATURE
MAXIMUM DESIGN PRESSURE
CORRESPONDING TEMPERATURE
Incorporation of Linear Scaling Relations into Automatic Mechanism Generation...Richard West
Presented at the 2017 AIChE Annual Meeting on October 31, 2017, by Richard H. West and C. Franklin Goldsmith.
https://www.aiche.org/conferences/aiche-annual-meeting/2017/proceeding/paper/304c-incorporation-linear-scaling-relations-automatic-mechanism-generation-heterogeneous-catalysis
Abstract:
To predict the selectivity and reactivity of novel catalysts at industrially relevant conditions requires a detailed microkinetic mechanism, comprising many elementary reactions. Recent advances such as such as the work of Ulissi et al [5] use a combination of scaling relations, machine learning, and DFT calculations, to gradually refine a microkinetic model until the rate limiting steps have been calculated with sufficient accuracy to be confident that they are correctly identified. However, such a system requires as input a comprehensive kinetic model containing all the possible pathways. Our recently developed Reaction Mechanism Generator for Heterogeneous Catalysis (RMG-Cat) [3], built upon the open-source RMG software primarily used for gas-phase pyrolysis and combustion [1,2], can provide such mechanisms ab inito: the user supplies just the initial conditions (eg. reactant composition, temperature, pressure) and the software predicts all the possible reactions, estimates the thermochemical and kinetic parameters, solves the governing equations, and decides which reaction pathways to include and explore further. RMG-Cat makes its decisions regarding which pathways to explore and which to ignore, using the estimated parameters, so it is important that the estimates are reasonable, even if the important parameters will be refined with more accurate calculations later in the model development process.
Linear Scaling Relations (LSRs) can provide reasonable estimates of adsorption energies in a very computationally efficient manner [4-6]. We have now implemented linear scaling relationships for the estimation of adsorption energies in the RMG-Cat software. Our database of parameters is organized in a hierarchical tree structure, enabling detailed functional group descriptions to be used when data are available and more general descriptions to be used when necessary. We include parameters to describe many adsorbates on a range of metal surfaces, and a framework to re-train the parameters whenever new data are available.
[1] Gao, C.W. et al., Comput. Phys. Commun., 203, 212-225, (2016) http://doi.org/10.1016/j.cpc.2016.02.013
[2] RMG - Reaction Mechanism Generator, open-source software, RMG-Py. http://reactionmechanismgenerator.github.io
[3] Goldsmith, C. F., West, R. H., J. Phys. Chem. C., 121 (18), 9970–9981 http://doi.org/10.1021/acs.jpcc.7b02133
[4] Medford, A. J. et al., Topics in Catalysis (2013) 57, 135-142
[5] Ulissi, Z. W. et al., Nature Comm. (2017) 8, 14621-14627
[6] Hummelshøj, J.S. et al., Angewandte Chemie International Edition (2011) 51, 272-274
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
Fundamentals of Suspensions & Dispersion's
0 INTRODUCTION
1 NATURE OF SURFACE FORCES
2 STABILITY AND THE STATE OF DISPERSION OF
SUSPENDED PARTICLES
3 MECHANISMS OF FLOCCULATION
4 STRUCTURE OF FLOCCULATED SUSPENSIONS
4.1 Dilute Suspensions
4.2 Concentrated Suspensions
5 STRUCTURE OF STABLE SUSPENSIONS OF
MONODISPERSE PARTICULATES
6 SUMMARY OF STRUCTURES
7 PARTICLE PACKING
8 RHEOLOGY
8.1 Basic Rheological Concepts
8.2 Colloidally Stable Suspensions
8.2.1 Spherical Particles of around 1 µm
8.2.2 Effect of Particle Size Distribution
8.2.3 Effect of Particle Shape
8.2.4 Submicron Particles
8.2.5 Very Concentrated Systems
8.3 Rheology of Flocculated / Aggregated Systems
8.3.1 Dilute Flocculated Systems
8.3.2 Concentrated Flocculated Systems
8.3.3 Time and History Effects
8.3.4 Slip and Fracture
8.3.5 Behavior of Flocculated Cakes in Compression
8.4 Summary of Rheology
Deflocculated Suspensions
Flocculated Suspensions
9 SEDIMENTATION OF SMALL PARTICLES
9.1 Very Dilute Particles
9.2 Concentrated Systems
9.3 Polydisperse Systems
9.4 Flocculated Systems
10 ELECTROKINETIC BEHAVIOR
11 A NOTE ON MAKING DISPERSIONS AND SUSPENSIONS
12 References
13 Figures
Fig 1a Potential Energy Diagram for Steric Stabilization
Fig 1b PE Diagram for Electrostatic Stabilization
Fig 1c Combined Stabilization
Fig 2&3 DIFFERENT TYPES OF FLOCCULATION MECHANISM IN WHICH POLYMERIC SPECIES ARE INVOLVED
Fig 4 Rheological Behavior
Fig 5 Relative Viscosity versus Volume Fraction for Polystyrene Spheres in Water
Fig 6 Time Dependent Flow Behavior of Very Concentrated Suspensions
Fig 7 Flow curves for Flocculated Dispersions
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
Turbulent Heat Transfer to Non Newtonian Fluids in Circular TubesGerard B. Hawkins
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 THE INTEGRATION OF THE ENERGY EQUATION
5 THE EDDY VISCOSITY FOR NON-NEWTONIAN AND DRAG REDUCING FLUIDS
6 THE CALCULATION OF HEAT TRANSFER
COEFFICIENTS FOR NON-NEWTONIAN AND DRAG
REDUCING FLUIDS IN TURBULENT PIPE FLOW
6.1 General
6.2 Drag Reducing Fibre Suspensions
6.3 Transition Delay
7 NOMENCLATURE
8 BIBLIOGRAPHY
Overflows and Gravity Drainage Systems
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 OUTLINE OF THE PROBLEM
5 DESIGNING FOR FLOODED FLOW
6 DESIGNING NON-FLOODED PIPELINES
6.1 Vertical Pipework
6.2 From the Side of a Vessel
6.3 Established (uniform) Flow in Near-horizontal Pipes
6.4 Non-uniform Flow
7 NON-FLOODED FLOW IN COMPLEX SYSTEMS
8 ENTRAINING FLOW
9 SIMPLE TANK OVERFLOWS
9.1 Venting of the Tank
10 BIBLIOGRAPHY
11 NOMENCLATURE
TABLE
1 GEOMETRICAL FUNCTIONS OF PART-FULL PIPES
FIGURES
1 TYPICAL SEQUENCE OF SURGING FLOW
2 DESIGNING FOR FLOODED FLOW
3 CAPACITY OF SLOPING PIPELINES
4 OVERFLOW FROM SIDE OF VESSEL
5 METHODS OF AVOIDING LARGE CIRCULAR SIDE
OVERFLOWS
6 CAPACITY OF A GENTLY SLOPING PIPE AS A FUNCTION OF LIQUID DEPTH
7 COMPLEX PIPE SYSTEMS
8 REMOVAL OF ENTRAINED GASES
General Water Treatment For Cooling Water
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 CHOICE OF COOLING SYSTEM
4.1 ‘Once through' Cooling Systems
4.2 Open Evaporative Recirculating Systems
4.3 Closed Recirculating Systems
4.4 Comparison of Cooling Systems
5 MAKE-UP WATER QUALITY
6 FOULING PROCESSES
6.1 Deposition
6.2 Scaling
6.3 Corrosion
6.4 Biological Growth
7 CONTROL OF THE COOLING SYSTEM
7.1 ‘Once through' Cooling Systems
7.2 Closed Recirculating Systems
7.3 Open Evaporative Cooling Systems
TABLES
1 RELATIVE IMPORTANCE OF FOULING PROCESSES AND INSTALLED COSTS
2 WATER QUALITY PARAMETERS
FIGURES
1 PREDICTION OF CALCIUM CARBONATE SCALING
2 CALCIUM SULFATE SOLUBILITY
3 CALCIUM PHOSPHATE SCALING INDEX
Troubleshooting in Distillation Columns
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 FLOW DIAGRAM FOR TROUBLESHOOTING
5 GENERAL APPRAISAL OF PROBLEM
5.1 Is the Problem Real?
5.2 What Is the Magnitude of the Problem?
5.3 Is it the Column or the Associated Equipment which is Causing the Problem?
6 PROBLEMS IN THE COLUMN
6.1 Capacity Problems
6.2 Efficiency Problems
7 PROBLEMS OUTSIDE THE COLUMN
7.1 Effect of Other Units on Column Performance
7.2 Column Control System
7.3 Improper Operating Conditions
7.4 Auxiliary Equipment
8 USEFUL BACKGROUND READING
9 BIBLIOGRAPHY
FIGURES
1 FLOW DIAGRAM FOR TROUBLESHOOTING
2 DETERMINATION OF COLUMN CAPACITY
Determination of Inert Gas in Anhydrous Ammonia
ANHYDROUS AMMONIA: DETERMINATION OF INERT GASES
SCOPE AND FIELD OF APPLICATION
This packed-column GC method is suitable for the determination of hydrogen, nitrogen, oxygen, argon and carbon monoxide in anhydrous ammonia. The determinations of the gases are linear in the range O-100 ppm v/v.
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
Distillation Sequences, Complex Columns and Heat IntegrationGerard B. Hawkins
Distillation Sequences, Complex Columns and Heat Integration
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 SEQUENCING OF SIMPLE COLUMNS
4.1 Sidestream Columns
4.2 Multi-Feed Columns
5 SIMPLE COLUMN SEQUENCING AND HEAT
INTEGRATION INTERACTIONS
5.1 Energy Quantity and Quality
5.2 Heat Integration within the Total Flowsheet
6 COMPLEX COLUMN ARRANGEMENTS
6.1 Indirect Sequence with Vapor Link
6.2 Sidestream Systems
6.3 Pre-Fractionator Systems
7 COMPLEX COLUMNS AND HEAT INTEGRATION
INTERACTIONS
FIGURES
1 DIRECT AND INDIRECT SEQUENCES
2 A SINGLE SIDESTREAM COLUMN REPLACING 2
SIMPLE COLUMNS
3 A TYPICAL MULTI-FEED COLUMN
4 TYPICAL GRAND COMPOSITION CURVE
5 TYPICAL INDIRECT SEQUENCE WITH VAPOUR LINK
6 SIDESTREAM STRIPPER AND SIDESTREAM
RECTIFIER
7 SIMPLEST PRE-FRACTIONATOR SYSTEM
8 SIMPLEST PRE-FRACTIONATOR SYSTEM
9 PETLYUK COLUMN
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
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
Psychrometry
0 INTRODUCTION / PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 PSYCHROMETRIC CHARTS
5 EXAMPLE CALCULATION
6 CHARTS FOR SPECIFIC SYSTEMS
7 BIBLIOGRAPHY
FIGURES
1 GROSVENOR CHART (Humidity vs. Temperature)
FOR AIR-WATER VAPOR AT 1.0133 bar
2 MOLLIER CHART (Enthalpy vs. Humidity) FOR
NITROGEN-TOLUENE VAPOR AT 100 kPa
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
Isothermal Methanol Converter (IMC) UA Distribution AnalysisGerard B. Hawkins
Isothermal Methanol Converter (IMC) UA Distribution Analysis - Case Study: #0630416GB/H; ACME Co. 9,000 MTD MeOH
This converter uses plates instead of tubes to remove the heat from the reaction gas. The use of the plates and the orientation allow the heat transfer within the converter to be more accurately controlled to follow the maximum rate line.
This case study examines the Radial Flow – Isothermal Methanol Converter (IMC) for ACME Co. 9,000 MTD, based on the Casale Isothermal Methanol Converter (IMC) design.
Solid Catalyzed Gas Phase Reactor Selection
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 ADIABATIC REACTORS
4.1 Single Bed Reactors
4.2 Divided Bed Reactors
4.3 Moving Bed Reactors
4.4 Radial Flow Reactors
5 NON ADIABATIC REACTORS
5.1 Tubular Reactor with External Heating/Cooling
5.2 Tube Cooled Reactors
5.3 Autothermal Reactors
5.4 Hot/Cold Shot Reactors
5.5 Divided Bed Reactors with Intercooling
5.6 Radial Flow Reactors with Intercooling
5.7 Fluid Bed Reactors
6 NOTES ON USING REACTOR SELECTION
GUIDE (TABLE 1)
TABLE
1 REACTOR SELECTION GUIDE
FIGURES
1 TUBULAR REACTOR: EXAMPLE OF CATALYST IN ANNULAR TUBES COOLED BY STEAM RAISING
2 AUTOTHERMAL REACTOR: CATALYST BED COOLED BY INFLOWING GAS IN TUBES
3 COLD SHOT CONVERTER: FIXED ADIABATIC BEDS WITH INTERBED QUENCH GAS MIXING
Determination of Residue on Evaporation in Anhydrous AmmoniaGerard B. Hawkins
Determination of Residue on Evaporation in Anhydrous Ammonia
1 SCOPE AND FIELD OF APPLICATION
This method is suitable for the determination of the residue left after evaporation i.e., the non-volatile material in ammonia solution.
2 PRINCIPLE
A known weight of sample is evaporated to dryness in a platinum dish on a steam bath. The increase in mass of the dish is measured.
TEMPERATURE MEASUREMENT:
RESISTANCE ELEMENTS AND THERMOCOUPLES
SPECIFICATION OF FUNCTION
DESCRIPTION OF FLUID
NORMAL OPERATING TEMPERATURE
REQUIRED TEMPERATURE RANGE
ALARM SETTINGS
TRIP SETTINGS
FLUID VELOCITY
REYNOLDS NUMBER
LINE SIZE
LINE REFERENCE
EQUIPMENT REFERENCE
NOZZLE SIZE
MINIMUM DESIGN PRESSURE
CORRESPONDING TEMPERATURE
MAXIMUM DESIGN PRESSURE
CORRESPONDING TEMPERATURE
Incorporation of Linear Scaling Relations into Automatic Mechanism Generation...Richard West
Presented at the 2017 AIChE Annual Meeting on October 31, 2017, by Richard H. West and C. Franklin Goldsmith.
https://www.aiche.org/conferences/aiche-annual-meeting/2017/proceeding/paper/304c-incorporation-linear-scaling-relations-automatic-mechanism-generation-heterogeneous-catalysis
Abstract:
To predict the selectivity and reactivity of novel catalysts at industrially relevant conditions requires a detailed microkinetic mechanism, comprising many elementary reactions. Recent advances such as such as the work of Ulissi et al [5] use a combination of scaling relations, machine learning, and DFT calculations, to gradually refine a microkinetic model until the rate limiting steps have been calculated with sufficient accuracy to be confident that they are correctly identified. However, such a system requires as input a comprehensive kinetic model containing all the possible pathways. Our recently developed Reaction Mechanism Generator for Heterogeneous Catalysis (RMG-Cat) [3], built upon the open-source RMG software primarily used for gas-phase pyrolysis and combustion [1,2], can provide such mechanisms ab inito: the user supplies just the initial conditions (eg. reactant composition, temperature, pressure) and the software predicts all the possible reactions, estimates the thermochemical and kinetic parameters, solves the governing equations, and decides which reaction pathways to include and explore further. RMG-Cat makes its decisions regarding which pathways to explore and which to ignore, using the estimated parameters, so it is important that the estimates are reasonable, even if the important parameters will be refined with more accurate calculations later in the model development process.
Linear Scaling Relations (LSRs) can provide reasonable estimates of adsorption energies in a very computationally efficient manner [4-6]. We have now implemented linear scaling relationships for the estimation of adsorption energies in the RMG-Cat software. Our database of parameters is organized in a hierarchical tree structure, enabling detailed functional group descriptions to be used when data are available and more general descriptions to be used when necessary. We include parameters to describe many adsorbates on a range of metal surfaces, and a framework to re-train the parameters whenever new data are available.
[1] Gao, C.W. et al., Comput. Phys. Commun., 203, 212-225, (2016) http://doi.org/10.1016/j.cpc.2016.02.013
[2] RMG - Reaction Mechanism Generator, open-source software, RMG-Py. http://reactionmechanismgenerator.github.io
[3] Goldsmith, C. F., West, R. H., J. Phys. Chem. C., 121 (18), 9970–9981 http://doi.org/10.1021/acs.jpcc.7b02133
[4] Medford, A. J. et al., Topics in Catalysis (2013) 57, 135-142
[5] Ulissi, Z. W. et al., Nature Comm. (2017) 8, 14621-14627
[6] Hummelshøj, J.S. et al., Angewandte Chemie International Edition (2011) 51, 272-274
Presentation given by George Romanos of the National Center for Scientific Research “Demokritos” (NCSRD), Greece, on "CO2QUEST - Fluid Properties and phase behaviour of CO2 with impurities" at the EC FP7 Projects: Leading the way in CCS implementation event, London, 14-15 April 2014
Neutron evaporation spectra alongwith γ-multiplicity has been measured from the 185Re* compound nucleus at the excitation energies ~27 and 37 MeV. Statistical model analysis of the experimental data has been carried out to extract the value of the inverse level density parameter k at different angular momentum regions (J) corresponding to different γ-multiplicity. It is observed that, for the present system the value of k remains almost constant for different J. The present results on the angular momentum dependence of the nuclear level density (NLD) parameter ã (=A/k), for nuclei with A ~180 is quite different from our earlier measurements in case of light and medium mass systems. The present analysis provides useful information to understand the angular momentum dependence of NLD at different nuclear mass regions.
ISES 2013 - Day 2 - Professor John M. Dhaw (Professor, University of Albert...Student Energy
Game-Changing Technologies In The Oil and Gas Industry
How does the shale gas situation in the world change energy markets, are oil sands a part of the future and can subsea help provide the future with energy?
ISES 2013 - Professor John M. Shaw (Professor, University of Alberta) - Ener...Student Energy
How does the shale gas situation in the world change energy markets, are oil sands a part of the future and can subsea help provide the future with energy?
EXPERIMENTAL INVESTIGATION ON THERMAL PERFORMANCE OF POROUS RADIANT BURNER AN...BIBHUTI BHUSAN SAMANTARAY
This paper presents the heat transfer characteristics of a
self-aspirating porous radiant burner (SAPRB) that operates
on the basis of an effective energy conversion method between
flowing gas enthalpy and thermal radiation. The temperature
field at various flame zones was measured experimentally by
the help of both FLUKE IR camera and K-type thermocouples.
The experimental setup consisted of a two layered domestic
cooking burner, a flexible test stand attached with six K-type
thermocouples at different positions, IR camera, LPG setup
and a hot wire anemometer. The two layered SAPRB consisted
of a combustion zone and a preheating zone. Combustion zone
was formed with high porosity, highly radiating porous
matrix, and the preheating zone consisted of low porosity
matrix. Time dependent temperature history from
thermocouples at various flame zones were acquired by using
a data acquisition system and the temperature profiles were
analyzed in the ZAILA application software environments. In
the other hand the IR graphs were captured by FLUKE IR
camera and the thermographs were analyzed in the
SMARTView software environments. The experimental results
revealed that the homogeneous porous media, in addition to
its convective heat exchange with the gas, might absorb, emit,
and scatter thermal radiation. The rate of heat transfer was
more at the center of the burner where a combined effect of
both convection & radiation might be realized. The maximum
thermal efficiency was found to be 64% which was having a
good agreement with the previous data in the open literature.
Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube ...A Behzadmehr
The growth rate and uniformity of Carbon Nano Tubes (CNTs) based on Chemical Vapor Deposition (CVD)
technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as
carbon source and mixture of argon and hydrogen as carrier gas enters into a horizontal CVD reactor at
atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
We would send hard copy of Journal by speed post to the address of correspondence author after online publication of paper.
We will dispatched hard copy to the author within 7 days of date of publication
Radial Heat Transport in Packed Beds-III: Correlations of Effective Transport...inventionjournals
The reliability and accuracy of experimental with predictions data of two models ("MC model" Marshall and Coberly model, [1] and modified model by Ibrahim et al. [2] are investigated for the effective radial thermal conductivity (Ker), and the wall heat transfer coefficient (hw) in packed beds in the absence of chemical reactions. The results were evaluated by the modified mathematical model as to the boundary bed inlet temperature; (To) number of terms of the solution series and number of experimental points used in the estimate. Very satisfactory was attained between the predicted and measured temperature profiles for a range of experiments. These cover a range of tube to (equivalent) particle diameter ratios from dt /dp = 4 to 10; Reynolds numbers ranged between 3.8-218 for particle, and elevated pressure from 11 to 20 bar for particle catalyst pellets. In all cases the fluid flowing throughout the bed has been air. The results indicate to the choice of the inlet boundary condition can have a large impact on the values of obtained parameters. And model parameters have been shown to be dependent on the pressure inside the reactor. The following correlations for both (hw) and (Ker) respectively under a given conditions obtained by using multiple regressions of our results that based on the modified mathematical model: Nuw = 67.9Re0.883(dt /dp) -0.635(P/Po) -1.354 Ker = 0.2396 + 0.0041Re The results accuracy of these correlations obtained from the modified mathematical model are more than the results accuracy of correlations obtained from MC model with respect to experimental data; these accuracy of both correlations reach up to 91% and 65% for (hw) and (Ker) respectively; which these results indicate to the reliability
Design of Controllers for Continuous Stirred Tank ReactorIAES-IJPEDS
The objective of the project is to design various controllers for temperature control in Continuous Stirred Tank Reactor (CSTR) systems. Initially Zeigler-Nichols, modified Zeigler-Nichols, Tyreus-Luyben, Shen-Yu and IMC based method of tuned Proportional Integral (PI) controller is designed and comparisons are made with Fuzzy Logic Controller. Simulations are carried out and responses are obtained for the above controllers. Maximum peak overshoot, Settling time, Rise time, ISE, IAE are chosen as performance index. From the analysis it is found that the Fuzzy Logic Controller is a promising controller than the conventional controllers.
A simple simulation model for oxidative coupling of methane
Kinetics & Reactor Modeling
1. Kinetics and Fixed-Bed Reactor Modeling of
Butane Oxidation to Maleic Anhydride
Ramesh K. Sharma and David L. Cresswell
Systems Engineering Group, Federal Institute of Technology, CH-8092 Zurich, Switzerland
Esmond J. Newson
Swiss Aluminium R&D, CH-8212 Neuhausen, Switzerland
Selective oxidation kinetics of n-butane to maleic anhydride in air were studied
over a commercial, fixed-bed vanadium-phosphor oxide catalyst. The temperature
range was 573-653 K with butane concentrations up to 3 mol % in the feed, which
is within flammability limits but below ignition temperatures.
The rate data were modeled using power law kinetics with product inhibition and
included total oxidation and decomposition reactions. Kinetic parameters were es-
timated using a multiresponse, nonlinear regression algorithm showing intercorre-
lation effects. The kinetics were combined with independent measurements of catalyst
diffusivity and reactor heat transfer using a one-dimensional heterogeneous reactor
model. Model predictions and observed temperatures and concentrations from non-
isothermal pilot plants were compared up to 115 days on stream. Agreement was
acceptable with inlet butane concentrations up to 2.7 mol %. For example, runaway
was predicted at a salt temperature 3 K higher than observed. Effectiveness factors
around the hot spot were estimated at 0.6 with the catalyst surface temperature 2-
3 K higher than the average gas temperature.
Introduction
For economic and ecological reasons, n-butane is replacing runaway situations in commercial pilot-plant reactors.
benzene as the major feedstock for the production of maleic Prior kinetic studies have been undertaken from either of
anhydride. Enhanced catalyst activity and selectivity (Budi et two experimental viewpoints. The first and more fundamental
al., 1982),together with anhydrous, organic solvent absorption approach is the identification of intermediate surface species
downstream (Neri and Sanchioni, 1982), make the economics and their relative concentrations to understand the reaction
for the fixed-, or fluidized-bed process exbutane particularly mechanism and different reaction pathways (Centi et al., 1988;
favorable. More recently, a recirculating solids reactor has been Hodnett, 1987; Wenig and Schrader, 1986). Many such pub-
described, which optimizes the best features of fixed and flui- lications, however, fail to quantify kinetics for subsequent
dized beds (Contractor et al., 1988). reaction engineering and reactor optimization. The alternate
Whatever the preferred technology, knowledge of the in- approach is to obtain intrinsic reaction data, which is then
trinsic kinetics is essential for optimizing the reactor design confronted with different empirical and mechanistic models
(Schneider et al., 1987; Wellauer et al., 1986). For safety in (Centi et al., 1985). This approach requires statistical inter-
reactor operation with respect to temperature runaway at high pretation of the data to discriminate among different models
butane inlet concentrations, a study has been made (Sharma and to show intercorrelation of parameters thus selecting the
et al., 1984b), whose kinetics were used for comparison of most probable kinetic parameters (Schneider et al., 1987;
Sharma et al., 1984b).
The latter approach was chosen for this work whose purpose
Correspondence concerning this article should be addressed to E. J. Newson, Paul Scherrer
Institute, Dept. FS, CH-5232 Villigen PSI, Switzerland. is to develop an intrinsic kinetic model, which is not only
Present address: R. K. Sharma, Dept. of Chemical Engineering, University of Saskatch- consistent with laboratory and pilot-plant kinetic measure-
ewan, Saskatoon, Canada, S7N OWO: D. L. Cresswell, Chemicals and Polymers Ltd., P.O.
Box 8, The Heath, Runcorn, Cheshire, England, WA7 4QD. ments but also capable of being combined with heat and mass
AIChE Journal January 1991 Vol. 37, No. 1 39
2. transport steps to predict nonisothermal, fixed bed, pilot-plant CAHIO+ 3.50z-c4H203 i - 4 H z 0 (1)
data at commercial conditions. The kinetic work was accom-
plished in three stages first using isothermal, differential rate C4HZ03 p 0 2 - ( 6 - 2p)CO + (2p - ;!)CO
+ + HzO (2)
data, then isothermal integral rate data from pilot plants, and
finally testing the scale-up properties of the reactor model C4H10+n02-(13-2n)CO+(2n- 91CO2 L ~ H , O (3)
against full-scale pilot-plant data.
The major results of this work are based on kinetic data p and n are stoichiometric coefficients dependent on the cat-
with an industrial catalyst at high ( 5 3 mol Vo) inlet butane alyst and are determined by kinetic measurements.
concentrations in the temperature range 573-653 K. Only data
from isothermal, integral pilot plants 1:1 with commercial Reactor equations
reactors and on equilibrated catalyst were used in the final M~~~balance:
analyses, the latter point being rarely conceded as important
in the literature (Centi et al., 1988; Schneider et al., 1987).
c
3
G m dPl
~- -
Data from laboratory reactors proved quite misleading in es- - a,?l ( j , R ci) (4)
tablishing the final triangular kinetic scheme with product in- (1-WfdZ
hibition. This surprising result was independently confirmed
(Buchanan, 1985). The temperature and concentration meas- Energy balance:
urements along the length of the pilot-plant reactor were crucial
for satisfactory parameter estimation, in addition to the pres-
ence of maleic anhydride at the inlet to the test section of the
dT
G CP - =
dz c
l = J ( - ~ J ) ? l C I ' ) R t i ) ( l - ~ ) - r : r..i.(r--Ts.)
o,.
reactor to avoid systematic errors.
For rigorous testing of the kinetic and reactor models, pre- (5)
dictions were compared with data from full-scale pilot-plant where 70) and R U ) are the effectiveness factor and reacrion
reactors operated near stability limits. The effects of salt tem- rate, respectively, for the jth reaction and a, is the stoichio-
perature, inlet butane concentration and feed rate were illus- metric number for the ith species in jth reactr m , which is
trated up to runaway conditions. The heterogeneity of the positive for product and negative for the reactant The pressure
model indicated effectiveness factors for the catalyst of about drop across the reactor was calculated using the Er :un equation
0.6 at the hot spot, but little difference between catalyst and (Ergun, 1952).
average gas temperatures.
Pellet equations:
The Reactor Model
An appropriate compromise between excessive complexity
r" dr
r"
(Deffl 2) c =
3
J= 1
-aIJR(j) (6)
and oversimplification for such highly exothermic fast reac-
tions is a one-dimensional, heterogeneous model (Froment,
1972). The utility of such a model has been shown for the
:s (Keifr"3 =
/=I
(7)
-(--la,)i?(j)
vapor-phase oxidation of benzene to maleic anhydride (Sharma
et al., 1984a). The effects of axial and radial dispersion of heat Boundary conditions:
and mass can be neglected as a first approximation, since they
are relevant only over a short length of the industrial reactor
r = O -dT - =dCi
= (] (8)
in the region of the hot spot. ' dr dr
Reaction network
A simplified reaction network consistent with the literature (9)
and preliminary work is a triangular kinetic model with the
desired reaction of butane to maleic anhydride in parallel with
an undesired, total oxidation reaction. The decomposition re-
action of maleic anhydride to oxidation products closes the
network. The stoichiometric equations are:
kb hb
Bi, = and Bih = -
Deif Kerf
Desired Reaction
The feed entrance conditions to the reactor are bnown. Such
Butane + Oxygen Maleic Anhydride + Water equations need to be written only for butane, oxygen, and
/
maleic anhydride. The corresponding concentrations for CO,
Total Oxidation Decomposition Reaction COz, and HzO can be calculated from reaction s: oichiometry
Reaction and rates. Using a modified Euler predictor-correc.tor method,
the interstitial fluid-phase equations were integrated stepwise
CO, CO2, HzO starting at the reactor inlet in conjunction with the pellet equa-
Total Oxidation Products tions employing two corrections for optimal usage and a slep
40 January 1991 Vol. 37, No. 1 AI<'hE Journal
3. Table 1. Heat transfer Parameters for Butane Oxidation to where Nu is the Nusselt number. The corresponding mass
Maleic Anhydride transfer coefficient can be calculated from the heat and mass
transfer analogy assuming Prandtl and Schmidt numbers for
krsefr = 1.1 W.m-'.K-'
air to be equal. Typical ratios for inter- and intraparticle trans-
hw*eff = 164-167 W.rn-'.K-'
(Bed +
inside wall) coefficient = 111-113 W.m-'.K-'
port rates are 0.66 for heat and 250 for mass.
Overall heat transfer coefficient (Uou) = 105-107 W.rn-*.K-'
Biot number for heat = 0.66-0.67 Kinetic model for butane oxidation to maleic
anhydride
Two types of mechanistic models were considered to describe
size of 2 cm (Seinfeld and Lapidus, 1974). The coupled set of the triangular kinetics for the selective oxidation of butane,
two-point boundary value equations describing the pellet were i.e., Langmuir-Hinshelwood and Redox mechanisms. Since
solved by orthogonal collocation using Jacobi polynomials as alternative kinetic data on a fluidized-bed catalyst of the same
expansion functions (Villadsen and Michelsen, 1978). Com- composition showed that, above 15% oxygen in the feed, the
putation time for a 3-m-long reactor was about 65 s on a CDC reaction rates were independent of oxygen concentration for
6400 computer. The effectiveness factors 101 for any reaction butane conversions up to lo%, the rate equations could be
are computed from the reaction rates integrated over the cat- simplified. Preliminary work in an isothermal integral reactor
alyst pellet: had also shown that a maleic anhydride adsorption term was
required to better describe concentration profiles in the reactor.
The rate equations for the best model were:
where a is a geometry factor and equal to 0, 1, and 2 for a R1 = klpy' desired reaction
(1 +K2P2)
slab, infinite cylinder, and sphere, respectively.
decomposition reaction
Heat transfer in the reactor tube
This has been described by a two-phase continuum model
based on a diffusional model for heat transfer that allows for R3 = k3py3 total oxidation reaction (19)
different temperature profiles in solid and fluid phases and
includes axial conduction in both the fluid and solid (Wellauer To minimize correlation, the rate constants were repara-
et al., 1982). The overall heat transfer coefficient is based on meterized as
the measured temperature difference between the central axis
of the bed and the coolant. It is derived by asymptotic matching
of thermal fluxes between one-dimensional and two-dimen-
sional models using the effective radial thermal conductivity,
kr,eff, the wall heat transfer coefficient, hw,eff.
and According where kj673 the value of the rate constant kj at the reference
is
to the model, the overall heat transfer coefficient U,, can be temperature of 673 K.
calculated by:
Interpretation of the isothermal data
Using the integral method of data analysis, the triangular
where al is the smallest root of kinetics leads to the following equations for the system under
isothermal conditions and assuming constant density and con-
stant number of moles
dpl - ( l - ' ) Q ( R , + R , )
Jo is a zero-order Bessel function of the real kind. Table 1 dZ Ft
shows typical values of these parameters for one set of ex-
perimental data from a full-scale pilot plant. dp2 - ('-'I ( R l - R 2 )
Q
dZ Ft
Local heat and mass transfer parameters
These parameters are essential to calculate surface conditions
from measurable gas-phase temperatures and concentrations.
The fluid-solid heat transfer coefficient is calculated from the
relation (Dwivedi and Upadhyay, 1977) @ - -( 1 - E)Q
- [(6-2p)R, + (13-2n)RJ
dZ Ft
where
p I , . . p 4 = dimensionless partial pressures of n-butane, mal-
0.57 eic anhydride, carbon dioxide and carbon mon-
= -Pr1'3Rei6Re, 2 50 (16)
E oxide, respectively
AIChE Journal January 1991 Vol. 37, No. 1 41
4. Z = axial bed length Table 2. Tortuosity Factor for Butane Oxidation Catalyst
Q = cross-sectional reactor area
€ = bed voidage Reynolds Peclet Effective ortuosity
No. (Rep) No. (Pep) Diffusivit) Factor
m*.s-'(x 10") 7
For given rate models, the above equations were integrated - ____
numerically and fitted to observed reactant-product distribu- Nitrogen Pulse
tions employing the nonlinear regression program of Klaus
and Rippin (1979) utilizing a Marquardt routine. Basic as- 62.2 1.88 1.99 3.3
50.1 1.93 2.15 3 .O
sumptions in the program are that there are no systematic 40.8 1.99 2.18 3 .O
deviations between the model and the physical system, the 28.4 2.12 2.53 2.6
residuals are only due to errors in the measured responses p 1 19.5 2.31 2.06 3.2
to p 4 , and the errors between different experiments are not 10.7 2.77 2.09 31
correlated. Allowance is made, however, for correlation be- Helium Pulse
tween measured responses in any single run. Initial estimates
of the parameters were obtained from graphical testing of the 399.9 1.92 2.90 4.9
363.2 1.94 2.61 5.1
data. The objective function S was minimized with respect to 274.6 2.03 2.72 4.8
the parameters g where
. P w
tracer gases. Since pulse broadening can also be cai sed by axial
dispersion in addition to pore diffusion, the formu was meas-
where mf is the number of responses in pattern f, nf is the ured independently using identical nonpoi oiis glais particles.
number of measurements in pattern f,Pis the number of dif- Table 2 shows the results of the experiments. An ,werage tor-
(g) x
ferent patterns and Mf is the determinant of the (Mf mf) tuosity of 3 was used for all the species of the react,on mixture,
moment matrix of residuals of pattern f. The convergence since the molecular weight of nitrogen is closer to wtane than
criterion for each parameter was 1 x helium.
Diffusion inside the catalyst Reactor systems used
The effective diffusivity of the catalyst was calculated by Kinetic parameters were estimated from experiments carried
combining Knudsen and bulk diffusion contributions in the out in isothermal differential and integral reactors both with
Bosanquet relation (Satterfield, 1970). crushed and commercial extrudate sizes. The overall experi-
mental program is described in Table 3. The diluted bed integral
reactor data, from which the kinetic parameters wer 2 ultimately
I
_-__ - 1
1
- + (26) determined, were fractional in design includiing fc )ur temper-
Deff DK,eff DB,eff ature levels, four concentration levels, and ihree flow rates.
In a series of 40 experiments, a total of 160 poin:s were ob-
where served, and at each point the concentrations of four species
were measured. The total of 640 data points were considered
sufficient to estimate the minimum expected si., -parameter
(27)
model.
The tortuosity factor r was measured experimentally, 7 is Table 3. Scope of Experiments: Butane Kinetics and Non-
the mean pore radius in cm. isothermal Operation
~-
Isothermal N misothermal
~-
Experimental Studies Laboratory Pilot-Plant 4ot-Plant
The catalyst consisted of promoted vanadium-phosphor ox- Differential Low/High High
ides whose commercial form is 3 x 10-3-m-dia. extrudates. Converioii Conversion
The pore-size distribution by mercury porosimetry showed
Total pres., atm 1.1 1-3 1-3
pores in the range 10-s-10-6 m diameter, a pore volume of Salt temp., "C 300-370 320-380 360-400
0.38 x lo-' m3-kg-', and a BET surface area of 1 1 x Total feed rate
m2.kg- I . kmolx lO-'h-' 1-3 50-240 40-80
Mole fraction (inlet)
C4HIO 0.005-0.03 0.005-0.03 (,018-0.027
Measurement of the tortuosity factor 0 2 0.21 0.21 0.21
A single-pellet string column was used to measure the tor- C4H203 0 0.001-0.002 0
tuosity under nonreacting conditions by pulse broadening Cat. particle size, mm 0.7, I 3 3
Cat. weight, g 1-3 600-740 1,800-2,280
(Cresswell and Orr, 1982). Nitrogen and helium were used as
42 January 1991 Vol. 37, No. 1 AICtiE Journal
5. The differential reactor was a 60-cm-long, 35-mm-dia. glass I 1
tube placed in an electrically heated furnace. The temperature
in the reactor bed was measured by a sliding chrome-alumel
P
z I 0 0.7~10-~ m
-
thermocouple placed in an axial thermowell. Dilution of the 0 7~1O-~rn
catalyst with glass beads of the same size in the ratio 1:9 0.56% butane in feed -
practically gave isothermal conditions, the temperature vari-
ation along the length of the reactor not exceeding 2°C. Butane
-
conversions did not exceed 8%. Under conditions chosen for
the differential reactor, calculations for interphase transport
limitations (Gunn, 1978) showed that mass transfer rates were -
at least 100 times larger than reaction rates, and gas-solid
temperature differences were a maximum of 2°C. cn
Y
To check the role of product inhibition on kinetics, liquid (394°C) (350°C) (315°C)
maleic anhydride was pumped to the inlets of both differential
and integral reactors. Practically this proved so difficult that 1.5 1.6 1.7
experiments were carried out only with diluted-bed integral K-'
I/T x 1 ~ 3 ,
reactors to emphasize kinetic measurements in the presence of Figure 1. Influence of pore diffusion on reaction rate.
maleic anhydride. In initial work, 3-mm commercial-size ex-
trudates were packed in a 4-m-long, 25-mm-ID reactor tube
immersed in a stirred molten saltbath for cooling. The tube
had several intermediate sampling points and an axial ther- Results and Discussion
mowell for temperature measurements. In the front 40% of To study intraparticle diffusion, experiments were carried
the reactor, an inert to catalyst ratio of 1:2 was used, concen- out in the differential reactor with 7 x 10-3-m and 0.7 x
tration measurements were made only in the second section of 10-3-m-dia. catalyst pellets. The observed rates are shown in
the reactor. In a more extensive work using up to 3 mol Vo Figure 1 indicating that pore diffusion is significant above 653
inlet butane, catalyst dilution was used in both sections: 1:l K. Isothermal, integral reactor experiments were, therefore,
in the front and 1:0.5 (inert) downstream. performed with 3 x 10-3-m-dia. extrudates operating below
The product analyses were performed in the same way as 653 K.
the differential reactor experiments. Maleic anhydride in the
product gases was absorbed in water and titrated against a
Kinetic parameters from the differential reactor
standard alkali solution. Butane concentrations at the inlet and
outlet were measured using gas chromatography, and CO and Since conversions were small and the inlet concentration of
C02 were analyzed by an infrared instrument. Any runs with maleic anhydride was zero, the rate data were first modeled
a carbon balance not within *3Vo were rejected. assuming two parallel reactions following power law rate
Safety aspects of reactor operation
The high inlet butane concentrations in air used in this work
were often between the upper and lower flammability limits Table 4. Four-Parameter Simplified Model for Butane
of 10.3 and 1.7% by volume, respectively (Perry et al., 1963). Kinetics: Differential Reactor
The spontaneous ignition temperature at the stoichiometric
kl = (0.94 f 0.73)10-6kmol~kg-1.s~'.atm0.66
concentration of 3.1% is 704 K, which increases to about 820 El = E3 = 63,600 f 13,800 kJ-kmol-'
K at 1.7%. Thus salt-bath temperatures of 673 K were not a1 = a3 = 0.66 f 0.16
exceeded in this work for safety reasons. k3 = (0.40 f 0.32)10-6kmol~kg-1.s-1.atm0-66
To further ensure safe operation if flammability limits and Correlation Matrix
ignition temperatures were simultaneously reached, standard
procedures for such laboratories were additionally used. Rup- k , 1.00
El 0.48 1.00
ture discs at the top of the reactor are large and quick enough k, 0.97 0.47 1.00
to act to mitigate emergencies, automatic hydrocarbon feed 0.99 0.53 -0.97 1.00
shut off with nitrogen purge for variations of pressure and
temperature outside predefined limits, visual and audible alarm Objective Function Value = - 288
facilities.
The possibility of flame propagation in the fixed catalyst
bed is minimal due to the packing acting as a flame arrestor.
'>*
r l
= 30.3% '>
r z
= 9.6%
In the equipment before the packing where the greatest danger
lies, entering hydrocarbodair mixtures are preheated only to '>
r3
= 24.2% '>
r4
= 15.9%
about 450 K, well below the spontaneous ignition temperature.
Thus, the first few centimeters of catalyst are used to bring Stoichiometric Coefficient: n = 5.5
the feed up to reaction temperatures, but safely inside the t -
- (standard deviation of residuals of fitted response/range of
packed bed. In equipment after the packing, temperatures drop response) x 100
1 = butane; 2 = maleic anhydride; 3 = C 0 2 ;4 = CO
sharply, while exit concentrations of butane are well below
f = 95% confidence limits
flammability limits in high conversion operation.
AIChE Journal January 1991 Vol. 37, No. 1 43
6. expressions. This six-parameter model showed that k3 and a3 Table 5. Seven-Parameter Model for Butane Kinetics:
were poorly determined and with a strong correlation between Isothermal Integral Reactor
rate constant and reaction order. A simplified four-parameter
model gave better estimates, which are shown in Table 4 with kl = (0.96 f 0.28)10-6kmol.kg-1.s-' .atm0.54
El = E3 = 93,100 f 5,700 kJ.mol-I
their single-parameter 95% confidence limits, correlation ma- a1 = a3 = 0.54 f 0.05
trix, objective function value and accuracy of fit. Joint pa- k2 = (0.29 f 0.14)10-5kmol-kg~1~s-1~atm-'
rameter confidence limits are expected to be somewhat larger, E2 = 155 f 35 MJ.kmol-I
about 50%. However, reducing the total number of parameters k, = (0.15 f 0.03)10-6 k m o l . g - ' . ~ - ' ~ a t m - ~ . ~ ~
K2 = 310 f 125 atm-'
from six to four. did not increase the objective function sig-
nificantly. Also, kl and k3 are highly correlated as are kl and Correlation Matrix
al, k3and a ] .The inability to control the maleic anhydride
and k, 1.00
feed to the inlet of the differential reactor probably led to El 0.68 1.00
systematic errors accompanying the differential data (Cropley, k3 0.87 0.55 1.00
1987). The estimate of 63,600 f 13,800 kJ/kmol-' is about a1 0.94 0.62 0.94 1.00
50% lower than subsequent integral data which included prod- kz 0.50 0.46 0.08 0.34 1.00
E2 -0.20 -0.31 0.09 -0.13 -0.83 1.00
uct inhibition at the reactor inlet. K2 0.69 0.63 0.39 0.44 0.61 -0.22 1 . M
Incorporating the kinetics from Table 4 into the reactor
model (Eqs. 4-1 1) and comparison with experimentally ob- Objective Function Value = - 606
served temperature and concentration profiles from a 4-m pilot-
plant reactor indicated severe discrepancies. Since reaction rates
were underpredicted in the front end and overestimated in the
tail end of the reactor, the kinetic model was modified to
include inhibition by the product maleic anhydride. This is '>
r3
= 6.8% '>
r 4
= 2.3%
consistent with an in situ FTIR study of n-butane selective
oxidation to maleic anhydride on V-P-0 catalysts in which the Stoichiometric Coefficients: p =I, n = 5.5
carbonyl stretching vibrations of maleic acid and maleic an- 8 - (standard deviation of residuals of fitted responsehange of
-
hydride were observed (Wenig and Schrader, 1986). response) x 100
1 = butane; 2 = maleic anhydride; 3 = CO,; 4 = CO
f = 95% confidence limits
Kinetic parameters from isothermal integral reactors
The initial integral reactor work in the 4-m tube, with only
the front end diluted, was combined with independent meas-
urements of maleic anhydride decomposition kinetics in a lab- ing the decomposition reaction. The resulting seven-parameter
oratory salt-bath reactor (Kuhn, 1979). The latter work led to model, Table 5, gave better estimates, decreased the objective
the use of incorrect stoichiometryp=2, n = 5.5, when applied function value, and decreased the 070 standard deviation in
to full-scale pilot-plant data where CO/C02 ratios were always comparison to Table 4. A maleic anhydride adsorption term
greater then 1.0. The more extensive work using up to 3 mol is now included, and the activation energy of the decomposition
'70 inlet butane with catalyst dilution in both sections was, reaction, 155 MJ.kmol-' compared to the desired reaction
therefore, used to determine all the kinetic parameters includ- 93.1 M J -kmol-I, clearly shows the disadvantage with respect
Table 6. Testing of the Butane Reactor Model against Pilot-Plant Data
Days On Stream 111 112 113 114 115
Operating Conditions 1.67 1.67 1.27 0.95 0.95
Feed rate, m3.h-'
Inlet butane conc., Vo 1.81 1.81 2.20 2.57 2.68
Salt temperature, "C 383 363 363 363 373
Experimental Data 2 600
Hot spot, "C 420 375 380-85 390-95 Runaway!
Conversion, '70 85 60 65 50 60-65
Selectivity*, 9
'
0 55 67 63 56 -
Model Predictions Runaway
Hot spot', "C 422 383 390 40 1 (Salt temp. = 376°C)
Conversion, T o 82.3 58.6 64.4 72.9 92
Selectivity, Vo 61.1 66.4 63.5 59.3 53
CO/C02 ratio 1.48 1.25 1.26 1.27 1.62
Overall heat trans. coeff. 106 104 93 83 85
UOu, W.m-2.K-1
'Hot spot refers to axial gas temperature
**selectivity = moles maleic anhydride, ma/mol.ma + mol.(CO+ C02)/4.
44 January 1991 Vol. 37, No. 1 AIChE Journal
7. A
Salt temp.
400°C
Inlet C4H,,%
1.82
Feed rate, m3/h
1.69
t ,, t
I
"o I
Reactor diameter = 0.024m
Feed flow rate = 0 96 kg m+ s
- I l6
0 390°C 1.86 1.68 VHSV = 703 h-'
380°C 0.75 1.65
0
450
fi 0
v
370°C
350°C
0.75
1.26
1.65
1.66
.m E 1
x"3 0
extrudate
6
-2
2 430 1.0
0
410 0.8 0"
E N
I
390
d 0.6 0"
8
1 370
0.4
-
2
v v v v
350
0.4 0.8 12 1.6 2.0 24 2.8 3.2 3.6 4.0 4.4 4.8 0.2
Reactor length, m
Figure 2. Maleic anhydride exbutane temperature pro- 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
Reactor length, rn
files at various operating conditions: experi-
mental catalyst Figure 3. Observed and predicted reactant, product and
temperature distributions in a full-scale re-
actor tube.
to selectivity of operation with high hot spots. A temperature
dependence of K2 could not be estimated with any certainty
so it was considered constant. days on stream, predicted conversion is much higher than
The relative contribution of reactions 2 and 3 to the for- observed due possibly to an observed reactor upset since op-
mation of CO and COz is reflected in the new values of the eration was on the verge of stability. Runaway was predicted
stoichiometric coefficients p = 1, n = 5.5. These values allow at a salt temperature 3°C higher than observed at a butane
CO/C02 ratios greater than 1.0 as frequently seen in non- inlet concentration of 2.68%.
isothermal operation with hot spots. In a series of runs, the model was further tested using an
experimental catalyst. The temperature profiles at the respec-
Model predictions vs. pilot-plant data tive conditions are shown in Figure 2 and the comparison of
For rigorous testing of the kinetic and reactor model, pre- experimental and predicted exit concentrations are shown in
dictions were compared with data from a full-scale pilot-plant Table 7 . For salt temperatures between 350-4OO0C, Figure 2
reactor operated near stability limits due to low feed rateJ and shows that temperatures are well predicted. Table 7 shows that
high hydrocarbon concentrations. The reactor was 25-mm-dia, conversion and selectivity are satisfactorily predicted especially
5-m-long, and fitted with an axial thermowell. The catalyst at higher conversions.
was very similar to that used for kinetic measurements. Table Observed and predicted concentration and temperature pro-
6 shows a comparison of model predictions vs. experimental files in a full-scale reactor tube are shown in Figure 3. The
data at different operating conditions. Conversion and selec- conversion of butane and selectivity to maleic anhydride are
tivity have been calculated at average gas temperatures given well predicted. The hot-spot temperature is underpredicted but
by the one-dimensional model while predicted hot-spot tem- within the uncertainty of the heat transfer coefficient (f10%)
peratures are for the gas at the axial location, using the two- (Wellauer et al., 1982). The combined CO + C 0 2 profile
dimensional continuum model of heat transfer, as described illustrates the relative contributions of reactions 2 and 3 and
earlier. The data from 111, 112 and 113 days on stream indicate tests the stoichiometry shown in Table 5 , p = 1, n = 5 . 5 . The
that the model satisfactorily predicts the effects of salt tem- CO/C02 ratio at the reactor exit as shown in Table 7 also tests
perature, inlet butane concentration, and feed rate. At 114 the suitability of the chosen stoichiometry.
Table 7. Testing the Model with Data from an Experimental Catalyst in Pilot-Plant Reactors
Conditions 1 2 3 4 5
Operating Conditions
Feed rate, m3.h-' 1.68 1.68 16
.5 1.65 1.66
Inlet butane conc., Vo 1.82 1.86 0.75 0.75 1.26
Salt temperature, "C 400 390 370 380 350
Inlet pressure, atm 19
. 1.65 1.64 1.64 1.62
Experimental/Predicted
Hot spot, "C 440/451 419/424 3801380 392/393 360/359
Conversion, % 90/90.8 84/77.2 81 /72.4 89.4/82.4 52.3/42.2
Selectivity, Yo 60/57.5 68/63.4 71.9/73.2 66.1/71.2 81.6/74.2
CO/C02 ratio 1.51/1.7 1.55/1.49 1.56h.37 1.57/1.51 1.43A.16
Pressure drop, atm 0.9/0.6 0.65/0.61 0.64/0.70 0.64/0.72 0.62/0.59
Heat transfer coeff., W.rn-'.K-' /lo7 /lo4 /lo6 /lo7 /lo2
AIChE Journal January 1991 Vol. 37, No. 1 45
8. Table 8. Heterogeneity of the Reactor Model
Operating Conditions Exp . Pied.
_____
Feed rate = 1.68 rn3.h-' Hot-spot temp. 440°C 45l'C
Salt-bath temp. = 400°C Conversion 90% 90.8%
Inlet butane = 1.82% Selectivity 60Vo 5E VO
- ____
Reactor Temperature, "C Effectiveness Factor Selectivity (- O/CO,>
Location Avg. Axial Pellet 91 92 73
m Surface
0.2 411.5 415.0 413.3 0.62 2.80 0.98 77.1 1.20
0.4 436.5 447.7 439.1 0.66 1.72 0.95 71.9 1.34
0.6 438.2 447.9 440.6 0.72 1.38 0.94 68.8 1.45
1.o 423.9 431.2 425.3 0.82 1.15 0.95 65.8 1.51
2.0 412.4 416.2 413.1 0.89 1.06 0.95 62.4 1.56
4.0 406.1 408.0 406.5 0.90 1.02 0.92 58.8 1.65
- __-_
The heterogeneity of the model is illustrated from data with Notation
a fresh catalyst at a salt temperature of 400°C. Table 8 shows u,, = number of moles of species I invohed in reaction J
that in the hot-spot region, the pellet surface is about 2-3°C A = reactor surface areaheactor volumc., m
higher than the average gas temperature. Intraparticle tem- b = half thickness of the active phase iri the ~tellet,m
perature gradients are negligible. By assuming a parabolic ra- C,= concentration of species I , mo1.m '
C, = specific heat of the gas, J .kg-'.K
dial temperature profile, it is possible to estimate that, in the dp = diameter of sphere of equal volume to surface area, m
hot-spot region, the average gas temperature in the tube cross- D = axial dispersion coefficient, m2.s-'
,
section is about 11"C lower than the axial value predicted by D,,, = effective diffusivity of species I , m z 3 - l
the model. E, = activation energy of reaction step], .I.mc I - '
E, = catalyst particle porosity
Figure 4 illustrates the region of stable operation in contrast Ft = total gas molar flow rate, mo1.s
to runaway, with feed rate as a parameter. The development G, = gas mass velocity, kg.m-*.s-'
of more active and selective catalysts would allow inlet butane hw,erf= apparent wall heat transfer coefficient, I .m2.K-'
concentrations of 4 5 % to be used in stable operation in axial- -m, = heat of reaction of step j , J.mol '
kg, h = interphase mass and heat transfer ( oefficie, it, m . s- I and
flow fixed-bed reactors. W .m-2. K-'
kgs = molecular conductivity of air, W m-'.K I
k, = rate constant of step j
kreff = effective radial thermal conductivity )f the bed,
Acknowledgment W.m-l .K-'
One of the authors (RKS) acknowledges financial support from K,,, = effective thermal diffusivity of the catalyst pellet,
KWF Bern, ETH Zurich and Swiss Aluminium, Neuhausen. The re- W .m-' .K-'
actor work was performed by Dr. J. P. Stringaro, Messrs. M. Bollinger K2 = maleic anhydride adsorption rate constanr atm-'
and H. P. Keller in Neuhausen. This article was presented in prelim- M = molecular weight
inary form at the AIChE Meeting in San Francisco, November 1984, n, p = number of moles of oxygen required/molt of reactant
the delay in publication being a requirement of a confidentiality agree- Pep = Peclet number of axial dispersion (ullrp/D6Tx)
ment. p , = mole fraction of species I in the mixture
Pr, Sc = Prandtl and Schmidt number for the gas
R = universal gas constant, J.mo1-I.k
r = distance from pellet center to any point insitie the pellet,
m
390 I I I I I I R U ) = intrinsic reaction rate of j , rno1.s- 'in-3
Re, = Reynolds number (G,dp/p)
0
380 Runaway region - S = objective function defined in Eq. 25
T , P = temperature and pressure, K and atm
U,,, = overall heat transfer coefficient, W . n ~ - ~ . h -'
u = linear gas velocity, m.s-l
E
0.
Z = distance from reactor inlet, m
5
L
360
-1
Stable operation Greek letters
$ 350 - (feed rate 0.95nm3/h)
2-Dim. model p = gas density, k g . r ~ - ~
70') = effectiveness factor for step j
340 I I I I I I I E = catalyst bed voidage
1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 4.6 p = gas viscosity, kg.m-l.s-'
Inlet mole fraction x 1 0 2 , % 7 = catalyst tortuosity factor
01 U) = exponent in rate equation for step .i
Figure 4. Region of 'STABLE' operation. Cl = cross-sectional area of reactor tube. niL
46 January 1991 Vol. 37, No. 1 AIChE Journal
9. Subscripts Single and Multiresponse Situations,” Comp. and Chem. Eng., 3,
105 (1979).
1, 2, 3, 4 = butane, maleic anhydride, CO,, CO
Kuhn, P., “Maleic Anhydride Decomposition,” internal report, Alu-
K, B = Knudsen, bulk suisse (1979).
G , MA = gas, maleic anhydride Malow, M., “Benzene or Butane for MAN,” Hydro. Processing, 149
0, p = bulk gas or reactor inlet, particle (Nov., 1980).
s, t = salt, tube Neri, A., and S. Sanchioni, US 4.314.946 to Ftalital S. p. A., “Process
for the Continuous Separation of Maleic Anhydride from Process
Gases,” (Feb. 9, 1982).
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AIChE Journal Januarv 1991 Vol. 37. No. 1 47