This document provides an overview of cooling tower selection and sizing. It describes different types of cooling towers classified by air draft (natural, forced, induced), flow pattern (crossflow, counterflow), and construction (package, field erected). The document contains theories of cooling tower operation related to vapor pressure and humidity. It includes steps for sizing cooling towers using graphical methods and calculating make-up water and motor requirements. The intended audience is engineers performing preliminary equipment selection and specification.
Engineers often use softwares to perform gas compressor calculations to estimate compressor duty, temperatures, adiabatic & polytropic efficiencies, driver & cooler duty. In the following exercise, gas compressor calculations for a pipeline composition are shown as an example case study.
Surge Control for Parallel Centrifugal Compressor OperationsVijay Sarathy
Parallel Centrifugal Compressor Operations
- Base Load Method
- Suction Side Speed Control Method
- Equal Flow Balance Method
- Equidistant to Surge Line Method
CENTRIFUGAL COMPRESSOR SETTLE OUT CONDITIONS TUTORIALVijay Sarathy
Centrifugal Compressors are a preferred choice in gas transportation industry, mainly due to their ability to cater to varying loads. In the event of a compressor shutdown as a planned event, i.e., normal shutdown (NSD), the anti-surge valve is opened to recycle gas from the discharge back to the suction (thereby moving the operating point away from the surge line) and the compressor is tripped via the driver (electric motor or Gas turbine / Steam Turbine). In the case of an unplanned event, i.e., emergency shutdown such as power failure, the compressor trips first followed by the anti-surge valve opening. In doing so, the gas content in the suction side & discharge side mix.
Therefore, settle out conditions is explained as the equilibrium pressure and temperature reached in the compressor piping and equipment volume following a compressor shutdown
This is course on Plant Simulation will show you how to setup hypothetical compounds, oil assays, blends, and petroleum characterization using the Oil Manager of Aspen HYSYS.
You will learn about:
Hypothetical Compounds (Hypos)
Estimation of hypo compound data
Models via Chemical Structure UNIFAC Component Builder
Basis conversion/cloning of existing components
Input of Petroleum Assay and Crude Oils
Typical Bulk Properties (Molar Weight, Density, Viscosity)
Distillation curves such as TBP (Total Boiling Point)
ASTM (D86, D1160, D86-D1160, D2887)
Chromatography
Light End
Oil Characterization
Using the Petroleum Assay Manager or the Oil Manager
Importing Assays: Existing Database
Creating Assays: Manually / Model
Cutting: Pseudocomponent generation
Blending of crude oils
Installing oils into Aspen HYSYS flowsheets
Getting Results (Plots, Graphs, Tables)
Property and Composition Tables
Distribution Plot (Off Gas, Light Short Run, Naphtha, Kerosene, Light Diesel, Heavy Diesel, Gasoil, Residue)
Oil Properties
Proper
Boiling Point Curves
Viscosity, Density, Molecular Weight Curves
This is helpful for students, teachers, engineers and researchers in the area of R&D, specially those in the Oil and Gas or Petroleum Refining industry.
This is a "workshop-based" course, there is about 25% theory and about 75% work!
At the end of the course you will be able to handle crude oils for your fractionation, refining, petrochemical process simulations!
Basic Unit Conversions for Turbomachinery Calculations Vijay Sarathy
Turbomachinery equipment like centrifugal pumps & compressors have their performance stated as a function of Actual volumetric flow rate [Q] & Head [m/bar]. The following tutorial describes how pump/compressor head can be expressed in energy terms as ‘kJ/kg’. Turbomachinery head expressed in kJ/kg describes, how many kJ of energy is required to compress 1 kg of gas for a given pressure ratio. The advantage of using energy terms to estimate absorbed power is that it is based on the amount of ‘mass’ compressed which is independent of pressure and temperature of a fluid.
Engineers often use softwares to perform gas compressor calculations to estimate compressor duty, temperatures, adiabatic & polytropic efficiencies, driver & cooler duty. In the following exercise, gas compressor calculations for a pipeline composition are shown as an example case study.
Surge Control for Parallel Centrifugal Compressor OperationsVijay Sarathy
Parallel Centrifugal Compressor Operations
- Base Load Method
- Suction Side Speed Control Method
- Equal Flow Balance Method
- Equidistant to Surge Line Method
CENTRIFUGAL COMPRESSOR SETTLE OUT CONDITIONS TUTORIALVijay Sarathy
Centrifugal Compressors are a preferred choice in gas transportation industry, mainly due to their ability to cater to varying loads. In the event of a compressor shutdown as a planned event, i.e., normal shutdown (NSD), the anti-surge valve is opened to recycle gas from the discharge back to the suction (thereby moving the operating point away from the surge line) and the compressor is tripped via the driver (electric motor or Gas turbine / Steam Turbine). In the case of an unplanned event, i.e., emergency shutdown such as power failure, the compressor trips first followed by the anti-surge valve opening. In doing so, the gas content in the suction side & discharge side mix.
Therefore, settle out conditions is explained as the equilibrium pressure and temperature reached in the compressor piping and equipment volume following a compressor shutdown
This is course on Plant Simulation will show you how to setup hypothetical compounds, oil assays, blends, and petroleum characterization using the Oil Manager of Aspen HYSYS.
You will learn about:
Hypothetical Compounds (Hypos)
Estimation of hypo compound data
Models via Chemical Structure UNIFAC Component Builder
Basis conversion/cloning of existing components
Input of Petroleum Assay and Crude Oils
Typical Bulk Properties (Molar Weight, Density, Viscosity)
Distillation curves such as TBP (Total Boiling Point)
ASTM (D86, D1160, D86-D1160, D2887)
Chromatography
Light End
Oil Characterization
Using the Petroleum Assay Manager or the Oil Manager
Importing Assays: Existing Database
Creating Assays: Manually / Model
Cutting: Pseudocomponent generation
Blending of crude oils
Installing oils into Aspen HYSYS flowsheets
Getting Results (Plots, Graphs, Tables)
Property and Composition Tables
Distribution Plot (Off Gas, Light Short Run, Naphtha, Kerosene, Light Diesel, Heavy Diesel, Gasoil, Residue)
Oil Properties
Proper
Boiling Point Curves
Viscosity, Density, Molecular Weight Curves
This is helpful for students, teachers, engineers and researchers in the area of R&D, specially those in the Oil and Gas or Petroleum Refining industry.
This is a "workshop-based" course, there is about 25% theory and about 75% work!
At the end of the course you will be able to handle crude oils for your fractionation, refining, petrochemical process simulations!
Basic Unit Conversions for Turbomachinery Calculations Vijay Sarathy
Turbomachinery equipment like centrifugal pumps & compressors have their performance stated as a function of Actual volumetric flow rate [Q] & Head [m/bar]. The following tutorial describes how pump/compressor head can be expressed in energy terms as ‘kJ/kg’. Turbomachinery head expressed in kJ/kg describes, how many kJ of energy is required to compress 1 kg of gas for a given pressure ratio. The advantage of using energy terms to estimate absorbed power is that it is based on the amount of ‘mass’ compressed which is independent of pressure and temperature of a fluid.
BOIL OFF GAS ANALYSIS OF LIQUEFIED NATURAL GAS (LNG) AT RECEIVING TERMINALSVijay Sarathy
Liquefied Natural Gas (LNG) is a cryogenic mixture of low molecular weight (MW) hydrocarbons with its chief component being methane. Its uses cover a gamut of applications from domestic & industrial use, power generation, to transportation fuel in its liquid form. LNG is transported in double-hulled ships specifically designed to handle low temperatures of the order of -1620C. As of 2012, there were 360 ships transporting more than 220 million metric tons of LNG every year. [1]
When LNG is received at most terminals, it is transferred to insulated storage tanks that are built to specifically hold LNG. These tanks can be above or below ground & keep the liquid at a low temperature to minimize evaporation & compositional changes due to heat ingress from the ambient. The temperature within the tank will remain constant if the pressure is kept constant by allowing the boil off gas (BOG) to escape from the tank. This is known as auto-refrigeration. BOG is collected & used as a fuel source in the facility or on the tanker transporting it. When natural gas is needed, LNG is warmed enough using heat exchangers to vaporize it called re-gasification process, prior to transferring it to the pipeline grid to various users.
Boil-off gas (BOG) management & assessment of LNG’s thermodynamic properties are key issues in the technical assessment of LNG storage. Increased vaporization process may negatively affect the stability and safety of the stored LNG. For these reasons the rate of vaporization (boil off rate) should be precisely determined in storage terminal energy systems. [2].
Presentation on Calculation of Polytropic and Isentropic Efficiency of natura...Waqas Manzoor
This presentation demonstrates comparison of calculation of Polytropic and Isentropic Efficiency of Natural Gas Compressor using Aspen HYSYS & using Manual Calculations. Complete derivation of equations of Polytropic and Isentropic efficiency, have also been demonstrated. The slight difference observed in the manually calculated values and Aspen HYSYS simulation, may be attributed to the calculation method of the software which is based on numerical integration.
Centrifugal compressor head - Impact of MW and other parametersSudhindra Tiwari
Please read the revised version.
A sequential approach to describe compressor head, pressure, system head and impact of MW and other suction parameters on head.
Oil & Gas Pipelines are often subjected to an operation called ‘Pigging’ for maintenance purposes (For e.g., cleaning the pipeline of accumulated liquids or waxes). A pig is launched from a pig launcher that scrapes out the remnant contents of the pipeline into a vessel known as a ‘Slug catcher’. The term slug catcher is used since pigging operations produces a Slug flow regime characterized by the alternating columns of liquids & gases. Slug catcher’s are popularly of two types – Horizontal Vessel Type & Finger Type Slug catcher. However irrespective of the type used, the determination of the slug catcher volume becomes the primary step before choosing the slug catcher type.
Fired Heaters-Key to Efficient Operation of Refineries and PetrochemicalsAshutosh Garg
Fired Heaters are a critical to successful operation of refineries and petrochemical plants. They are a major energy consumer as well as a major source of air pollution. There are also concerns about the run length of the heaters as well safety issues.
Air Cooled Heat Exchanger Design
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 SUITABILITY FOR AIR COOLING
4.1 Options Available For Cooling
4.2 Choice of Cooling System
5 SPECIFICATION OF AN AIR COOLED HEAT
EXCHANGER
5.1 Description and Terminology
5.2 General
5.3 Thermal Duty and Design Margins
5.4 Process Pressure Drop
5.5 Design Ambient Conditions
5.6 Process Physical Properties
5.7 Mechanical Design Constraints
5.8 Arrangement
5.9 Air Side Fouling
5.10 Economic Factors in Design
6 CONTROL
7 PRESSURE RELIEF
8 ASSESSMENT OF OFFERS
8.1 General
8.2 Manual Checking Of Designs
8.3 Computer Assessment
8.4 Bid Comparison
9 FOULING AND CORROSION
9.1 Fouling
9.2 Corrosion
10 OPERATION AND MAINTENANCE
10.1 Performance Testing
10.2 Air-Side Cleaning
10.3 Mechanical Maintenance
10.4 Tube side Access
11 REFERENCES
Gas Compression Stages – Process Design & OptimizationVijay Sarathy
The following tutorial demonstrates how to estimate the required number of compression stages and optimize the individual pressure ratio in a multistage centrifugal compression system.
Course by Chemical Engineering Guy
Check out full course:
http://www.chemicalengineeringguy.com/courses/aspen-plus-physical-properties-course/
Ask me for special discounts, or checkout "SURPIRSE" tab in my site for special discounts.
This is course on Process Simulation will show you how to model, manipulate and report thermodynamic, transport, physical and chemical properties of substances.
You will learn about:
Physical Property Environment
Physical Property Method & Method Assistant
Fluid and Property Packages
Physical property input, modeling, estimation and regression
Thermodynamic Properties (Material/Energy balances and Thermodynamic Processes)
Transport Properties for (Mass/Heat/Momentum Transfer)
Equilibrium Properties (Vapor-Liquid, Liquid-Liquid, etc...)
Getting Results (Plots, Graphs, Tables)
This is an excellent way to get started with Aspen Plus. Understanding the physical property environment will definitively help you in the simulation and flowsheet creation!
This is a "workshop-based" course, there is about 50% theory and about 50% practice!
Mechanical Constraints on Thermal Design of Shell and Tube ExchangersGerard B. Hawkins
Mechanical Constraints on Thermal Design of Shell and Tube Exchangers
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 STANDARD DIMENSIONS
4.1 Shell Diameters
4.2 Tube Lengths
4.3 Tube Diameters
4.4 Tube Wall Thicknesses
5 CLEARANCES
5.1 Tube Pitch
5.2 Pass Partition Lane Widths
5.3 Minimum 'U' Bend Clearance
5.4 Tube-to-Baffle Clearance
5.5 Baffle-to-Shell Clearance
5.6 Bundle-to-Shell Clearance
6 TUBESHEET THICKNESS
7 END ZONE LENGTHS
8 TUBE COUNTS
8.1 Program Correlations
8.2 Use of Tube count Tables
8.3 Graphical Layout
8.4 Use of Computer Programs
8.5 Tie Rods
TABLES
1 HEAT EXCHANGER SHELLS - GEOMETRICAL DATA
FOR INLET & OUTLET BRANCHES: PIPE WITH ANSI
150 FLANGE
2 HEAT EXCHANGER SHELLS - GEOMETRICAL DATA
FOR INLET & OUTLET BRANCHES: PIPE WITH ANSI
300 FLANGE
3 TEMA TIE ROD STANDARDS
FIGURES
1 DEFINITION OF TUBE PITCH, LIGAMENT THICKNESS & PASS PARTITION LANE WIDTH
2 DEFINITION OF PASS PARTITION LANE WIDTH FOR U-TUBES
3 BUNDLE TO SHELL CLEARANCES FOR DIFFERENT BUNDLE TYPES
4 ESTIMATED TUBESHEET THICKNESS FOR FIXED TUBE CONSTRUCTION
5 ESTIMATED TUBESHEET THICKNESS FOR U-TUBE CONSTRUCTION
6 END ZONE
7 EXAMPLE OF OPTU3 GRAPHICAL OUTPUT
BOIL OFF GAS ANALYSIS OF LIQUEFIED NATURAL GAS (LNG) AT RECEIVING TERMINALSVijay Sarathy
Liquefied Natural Gas (LNG) is a cryogenic mixture of low molecular weight (MW) hydrocarbons with its chief component being methane. Its uses cover a gamut of applications from domestic & industrial use, power generation, to transportation fuel in its liquid form. LNG is transported in double-hulled ships specifically designed to handle low temperatures of the order of -1620C. As of 2012, there were 360 ships transporting more than 220 million metric tons of LNG every year. [1]
When LNG is received at most terminals, it is transferred to insulated storage tanks that are built to specifically hold LNG. These tanks can be above or below ground & keep the liquid at a low temperature to minimize evaporation & compositional changes due to heat ingress from the ambient. The temperature within the tank will remain constant if the pressure is kept constant by allowing the boil off gas (BOG) to escape from the tank. This is known as auto-refrigeration. BOG is collected & used as a fuel source in the facility or on the tanker transporting it. When natural gas is needed, LNG is warmed enough using heat exchangers to vaporize it called re-gasification process, prior to transferring it to the pipeline grid to various users.
Boil-off gas (BOG) management & assessment of LNG’s thermodynamic properties are key issues in the technical assessment of LNG storage. Increased vaporization process may negatively affect the stability and safety of the stored LNG. For these reasons the rate of vaporization (boil off rate) should be precisely determined in storage terminal energy systems. [2].
Presentation on Calculation of Polytropic and Isentropic Efficiency of natura...Waqas Manzoor
This presentation demonstrates comparison of calculation of Polytropic and Isentropic Efficiency of Natural Gas Compressor using Aspen HYSYS & using Manual Calculations. Complete derivation of equations of Polytropic and Isentropic efficiency, have also been demonstrated. The slight difference observed in the manually calculated values and Aspen HYSYS simulation, may be attributed to the calculation method of the software which is based on numerical integration.
Centrifugal compressor head - Impact of MW and other parametersSudhindra Tiwari
Please read the revised version.
A sequential approach to describe compressor head, pressure, system head and impact of MW and other suction parameters on head.
Oil & Gas Pipelines are often subjected to an operation called ‘Pigging’ for maintenance purposes (For e.g., cleaning the pipeline of accumulated liquids or waxes). A pig is launched from a pig launcher that scrapes out the remnant contents of the pipeline into a vessel known as a ‘Slug catcher’. The term slug catcher is used since pigging operations produces a Slug flow regime characterized by the alternating columns of liquids & gases. Slug catcher’s are popularly of two types – Horizontal Vessel Type & Finger Type Slug catcher. However irrespective of the type used, the determination of the slug catcher volume becomes the primary step before choosing the slug catcher type.
Fired Heaters-Key to Efficient Operation of Refineries and PetrochemicalsAshutosh Garg
Fired Heaters are a critical to successful operation of refineries and petrochemical plants. They are a major energy consumer as well as a major source of air pollution. There are also concerns about the run length of the heaters as well safety issues.
Air Cooled Heat Exchanger Design
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 SUITABILITY FOR AIR COOLING
4.1 Options Available For Cooling
4.2 Choice of Cooling System
5 SPECIFICATION OF AN AIR COOLED HEAT
EXCHANGER
5.1 Description and Terminology
5.2 General
5.3 Thermal Duty and Design Margins
5.4 Process Pressure Drop
5.5 Design Ambient Conditions
5.6 Process Physical Properties
5.7 Mechanical Design Constraints
5.8 Arrangement
5.9 Air Side Fouling
5.10 Economic Factors in Design
6 CONTROL
7 PRESSURE RELIEF
8 ASSESSMENT OF OFFERS
8.1 General
8.2 Manual Checking Of Designs
8.3 Computer Assessment
8.4 Bid Comparison
9 FOULING AND CORROSION
9.1 Fouling
9.2 Corrosion
10 OPERATION AND MAINTENANCE
10.1 Performance Testing
10.2 Air-Side Cleaning
10.3 Mechanical Maintenance
10.4 Tube side Access
11 REFERENCES
Gas Compression Stages – Process Design & OptimizationVijay Sarathy
The following tutorial demonstrates how to estimate the required number of compression stages and optimize the individual pressure ratio in a multistage centrifugal compression system.
Course by Chemical Engineering Guy
Check out full course:
http://www.chemicalengineeringguy.com/courses/aspen-plus-physical-properties-course/
Ask me for special discounts, or checkout "SURPIRSE" tab in my site for special discounts.
This is course on Process Simulation will show you how to model, manipulate and report thermodynamic, transport, physical and chemical properties of substances.
You will learn about:
Physical Property Environment
Physical Property Method & Method Assistant
Fluid and Property Packages
Physical property input, modeling, estimation and regression
Thermodynamic Properties (Material/Energy balances and Thermodynamic Processes)
Transport Properties for (Mass/Heat/Momentum Transfer)
Equilibrium Properties (Vapor-Liquid, Liquid-Liquid, etc...)
Getting Results (Plots, Graphs, Tables)
This is an excellent way to get started with Aspen Plus. Understanding the physical property environment will definitively help you in the simulation and flowsheet creation!
This is a "workshop-based" course, there is about 50% theory and about 50% practice!
Mechanical Constraints on Thermal Design of Shell and Tube ExchangersGerard B. Hawkins
Mechanical Constraints on Thermal Design of Shell and Tube Exchangers
0 INTRODUCTION/PURPOSE
1 SCOPE
2 FIELD OF APPLICATION
3 DEFINITIONS
4 STANDARD DIMENSIONS
4.1 Shell Diameters
4.2 Tube Lengths
4.3 Tube Diameters
4.4 Tube Wall Thicknesses
5 CLEARANCES
5.1 Tube Pitch
5.2 Pass Partition Lane Widths
5.3 Minimum 'U' Bend Clearance
5.4 Tube-to-Baffle Clearance
5.5 Baffle-to-Shell Clearance
5.6 Bundle-to-Shell Clearance
6 TUBESHEET THICKNESS
7 END ZONE LENGTHS
8 TUBE COUNTS
8.1 Program Correlations
8.2 Use of Tube count Tables
8.3 Graphical Layout
8.4 Use of Computer Programs
8.5 Tie Rods
TABLES
1 HEAT EXCHANGER SHELLS - GEOMETRICAL DATA
FOR INLET & OUTLET BRANCHES: PIPE WITH ANSI
150 FLANGE
2 HEAT EXCHANGER SHELLS - GEOMETRICAL DATA
FOR INLET & OUTLET BRANCHES: PIPE WITH ANSI
300 FLANGE
3 TEMA TIE ROD STANDARDS
FIGURES
1 DEFINITION OF TUBE PITCH, LIGAMENT THICKNESS & PASS PARTITION LANE WIDTH
2 DEFINITION OF PASS PARTITION LANE WIDTH FOR U-TUBES
3 BUNDLE TO SHELL CLEARANCES FOR DIFFERENT BUNDLE TYPES
4 ESTIMATED TUBESHEET THICKNESS FOR FIXED TUBE CONSTRUCTION
5 ESTIMATED TUBESHEET THICKNESS FOR U-TUBE CONSTRUCTION
6 END ZONE
7 EXAMPLE OF OPTU3 GRAPHICAL OUTPUT
Performance Analysis of the Natural Draft Cooling Tower in Different SeasonsIOSR Journals
Cooling towers are the biggest heat and mass transfer devices that are in widespread use. In this
paper we use a natural draft counter flow cooling tower in investigating the performance of cooling tower in
different seasons. The humidity is defined as water particles present in air. The humidity is the major factor in
the atmosphere, it depends upon ambient temperature. Humidity is high in winter season and low in summer
season.
The performance of the natural draft cooling tower is dominated by wind speed, ambient air
temperatures and humidity in the atmospheric conditions. When the humidity is high in atmosphere, large
quantity of water is required for cooling condensate. When humidity is low in atmosphere, small quantity of
water is required for cooling condensate. The value of relative humidity in the atmosphere varies from place to
place and season. The different losses in the cooling tower such as drift losses, evaporation losses and blow
down losses can be calculated. The maintenance of cooling tower in the form of removal of scale or corrosion
plays important role in the performance of the tower. The performance of the natural draft cooling tower of 500
MW is evaluated.
Cooling Tower:-By Using More Efficient Equipment Increase EfficiencyMayursinh Solanki
This Project Is Done Over ONGC Hazira Plant At Phase-I Cooling Tower.In This Slide Show,We Want To Give You Some New Ideas About Equipment Like Fills,Drift Eliminator,Storage Tank,ect.
Comparative Study on NDCT with Different Shell Supporting StructuresIJTET Journal
Natural draft cooling towers are very essential in modern days in thermal and nuclear power stations. These are the hyperbolic shells of revolution in form and are supported on inclined columns. Several types of shell supporting structures such as A,V,X,Y are being used for construction of NDCT’s. Wind loading on NDCT governs critical cases and requires attention. In this paper a comparative study on reinforcement details has been done on NDCT’s with X and Y shell supporting structures. For this purpose 166m cooling tower with X and Y supporting structures being analyzed and design for wind (BS & IS code methods), seismic loads using SAP2000.
In this Thesis I will try to understand the concept associated with cooling towers and model a laboratory sized cooling tower in a software package called Engineering Equation Solver (EES). An example of system modelling is presented in this progress report, along with the comparison of a set of results with an experimental data from P.A Hilton Model H892 Bench top cooling tower with a maximum of 9% error. A user interface is also modelled to simulate off-design performance rather than conducting experiments. It also allows you to do additional scenarios that cannot be practically being done in lab,
like Relative humidity, etc.
Analysis of forced draft cooling tower performance using ansys fluent softwareeSAT Journals
Abstract In this project the cooling tower performance has been analyzed by varying air inlet parameters with different air inlet angles and by attaching a nozzle in air inlet. The cooling tower analyzed here is used specifically for small scale industries, which is forced draft counter-flow cooling tower with single module capacities from 10 to 100 cooling tons. In this project 50 tons cooling capacity model has been taken as reference model. The analysis has been done using computational fluid dynamics (CFD) ANSYS 14.5 software. The cooling tower models have been modeled using SOLIDWORKS 2013 software and they have been meshed using ICEM CFD 14.5 software. The meshed models have been analyzed using FLUENT software. The air inlet angles varied in horizontal direction, vertical direction and by combining both horizontal and vertical inclination. A convergent nozzle has been modeled and assembled to the inlet pipe. The temperature contours of the cooling tower models have been taken from the analysis. Based on the outlet cold water temperature, the improved effectiveness of the cooling tower model has been obtained.
Keywords: Forced draft cooling tower, Air inlet parameter, Convergent nozzle, Cooling ton capacity, Counter flow cooling tower, Ansys 14.5, Solidworks 2013, ICEM CFD 14.5, Effectiveness of cooling tower.
Warping and Residual Stress Analysis using the Abaqus Interface for MoldflowSIMULIA
Residual stresses may be introduced into plastic parts produced by the injection molding process. As a result, the part may warp or experience a reduction in strength. The design of an injection molded product can be improved if the effect of residual stresses on the final shape and performance of the product are predicted accurately. Abaqus and Moldflow can be used for this purpose. The residual stresses generated by the solidifi-cation of the plastic material are computed by Moldflow and transferred to Abaqus using the Abaqus Interface for Moldflow. The component can then be structurally analyzed with Abaqus to determine warpage and/or response to in-service loading. In this Technology Brief, this methodology is demonstrated with two case studies.
Working of Continuous Distillation Column jagdeep123
Distillation Column has been widely used in industrial area where chemical processing and waste water treatment plays a significant role. It is also used nowadays in solvent recovery processes.
Solve Heat Transfer Challenges Quickly and Cost-Effectively With Flow SimulationEngineering Technique
To realize the benefits of using flow simulation to resolve thermal issues quickly and cost-effectively, choose a CAD-integrated application like SolidWorks Flow Simulation software. SolidWorks Flow Simulation software provides a wide range of fluid-flow and heat-transfer capabilities, which designers can use to gain greater insight into product behaviour for many applications.
Seminar Presentation file for "Autodesk CFD for better building design" by Mr. ZHU ge.
Event Details
Seminar: Autodesk CFD for Better Building Design
Co-organized by: Autodesk / HKIBIM / IVE BIM Centre
With your BIM model, Autodesk® Simulation CFD software can provides computational fluid dynamics and thermal simulation analysis to help you create better interior and exterior design. A range of CFD modeling and thermal modeling tools are included for architectural and mechanical, electrical, and plumbing (MEP) applications. Model radiant heat transfer and occupant comfort; better predict contaminant dispersion and smoke migration in and around buildings. Study the long-term effects of diurnal heating. The Design Study Environment allows you to automate the creation of design studies, compare critical values, and predict design performance, optimize designs, and validate behavior before construction.
For more information about Autodesk® CFD: http://www.autodesk.com/products/cfd/overview
Seminar details:
Date & Time: 9-Sep-2015; 7:00pm – 8:30pm
Speaker: Ge Zhu, Technical Sales Specialist, Autodesk
He is major in Engineering Thermophysics, Master of Huazhong University of Science and Technology. He has 7 years for electrical thermal and datacenter CFD simulation experience.
Location: Lecture Theater LT-01, G/F, IVE (Morrison Hill), 6 Oi Kwan Road, Hong Kong
Agenda:
1. Why Simulation
2. Auotdesk CFD Features
3. Key Application Areas of Autodesk CFD
For any enquiry, please contact Mr. Waiky Leung at waiky.leung@autodesk.com
Advances in Ethylene Unit Pyrolysis Furnace Design and Optimization Training ...Karl Kolmetz
This course will guide the participates to develop key concepts and techniques
for the optimization of Ethylene Unit Pyrolysis Furnace Design and Optimization.
These key concepts can be utilized to make operating decisions that can improve
your unit’s performance.
Many aspects of fired heaters operations and management can be improved
including, energy utilization, product improvements, furnace tube life, and safety.
This cannot be achieved without first an understanding of basic fundamental
principles of design and operation. These principles need to be understood in
advance of operating and trouble shooting a process unit operation for the
manager or problem solving to be effective.
Actiflow is a young and dynamic engineering company with a broad expertise. We have an excellent team of engineers experienced in the fields of product design, aero- & hydrodynamics, CAE (Computer Aided Engineering) and systems & control. We are focused on delivering high quality solutions while keeping close cooperation with our clients.
We offer our services to a wide range of industries. Ranging from the building industry to the medical industry, from automotive to aerospace and from oil & gas to wind energy, our expertise proves its value.
Our engineering work is split into two main categories:
* Aero consulting: advising clients in the fields of aerodynamics, fluid flows, ventilation & air conditioning, fire & smoke, etc.
* Design engineering: Conceptual design and engineering of high-tech products, including prototyping and testing.
Similar to Engineering design guidelines cooling towers - rev01 (20)
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Storytelling For The Web: Integrate Storytelling in your Design ProcessChiara Aliotta
In this slides I explain how I have used storytelling techniques to elevate websites and brands and create memorable user experiences. You can discover practical tips as I showcase the elements of good storytelling and its applied to some examples of diverse brands/projects..
1. KLM Technology
Group
Practical Engineering
Guidelines for Processing
Plant Solutions
www.klmtechgroup.com
Page : 1 of 52
Rev: 01
July 2011
KLM Technology Group
#03-12 Block Aronia,
Jalan Sri Perkasa 2
Taman Tampoi Utama
81200 Johor Bahru
Malaysia
COOLING TOWER SELECTION AND
SIZING
(ENGINEERING DESIGN GUIDELINE)
Author:
Viska Mulyandasari
Checked by:
Karl Kolmetz
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
TABLE OF CONTENT
INTRODUCTION
Scope 4
Cooling Tower 5
GENERAL DESIGN CONSIDERATION
Components of a Cooling Tower 13
Tower materials 17
Cooling Tower Design Consideration 18
Operation Considerations 18
Improving Energy Efficiency of Cooling Towers 18
Tower Problems 20
DEFINITIONS 23
NOMENCLATURE 32
2. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 2 of 52
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July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
THEORY
Cooling Tower Performance 34
Vapor Pressure of Water 36
Humidity 37
Relative Humidity and Percent Humidity 38
Dew Point 39
Humidity Chart 39
Wet Bulb Temperature 41
Cooling Tower Sizing 41
APPLICATION
Example Case 1: Cooling Tower Sizing 46
Example Case 2: Make-Up Water Calculation 50
REFERENCES 49
CALCULATION SPREADSHEET 52
3. KLM Technology
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Practical Engineering
Guidelines for
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COOLING TOWER SELECTION AND
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ENGINEERING DESIGN GUIDELINES
Page 3 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
LIST OF TABLE
Table 1. Typical Problems and Trouble Shooting for Cooling Towers 22
Table 2. Psychrometric Table: Properties of Moist Air at 101 325 N/m2
42
LIST OF FIGURE
Figure 1. Schematic diagram of a cooling water system 5
Figure 2. Classifications of cooling towers 6
Figure 3. Atmospheric cooling tower 8
Figure 4. (a) Cross flow and (b) counter flow natural draft cooling tower 9
Figure 5. Forced draft cooling tower 10
Figure 6. Induced draft cooling tower 11
Figure 7. Crossflow type design 12
Figure 8. Counterflow type design 12
Figure 9. Range and approach 34
Figure 10. Phase diagram for water 37
Figure 11. Humidity chart for mixture of air and water vapor at a total pressure of
101.325 kPa (760 mmHg) 40
Figure 12. Measurement of wet bulb temperature 41
Figure 13. Nomograph of cooling-tower characteristics 44
Figure 14. Sizing chart for a counterflow induced-draft cooling tower 48
4. KLM Technology
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Practical Engineering
Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 4 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
INTRODUCTION
Scope
This design guideline assists engineers to understand the basic principles of cooling
towers. Cooling towers are commonly used to remove excess heat that is generated in
places such as power stations, chemical plants and even domestically in air
conditioning units. This equipment has recently developed into an important part of
many chemical plants. They represent a relatively inexpensive and dependable means
of removing low-grade heat from cooling water.
Cooling towers might be classified into several types based on the air draft and based
on the flow pattern. Each type of cooling tower has its own advantages and
disadvantages; thus the proper selection is needed based on the system operation.
Besides, the material selection of cooling tower is also important. Cooling towers
tends to be corrosive since it always has direct contact with the water. Proper material
selection or additional water treatment is then needed to keep the cooling tower safe.
Some theories are needed to be understood before an engineer start to sizing a
cooling tower. Cooling tower process is generally related with vapor pressure of water
and humidity. Those theories are briefly described in this guideline to provide the
basic understanding of its calculation. Cooling tower sizing can simply be done by
graphical methods. Some additional calculation such as water make-up, fan and
pump horsepower calculations are also explained in this guideline.
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Practical Engineering
Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 5 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Cooling Tower
Cooling towers are heat removal devices used to transfer process waste heat to the
atmosphere. Cooling towers make use of evaporation whereby some of the water is
evaporated into a moving air stream and subsequently discharged into the
atmosphere. As a result, the remainder of the water is cooled down significantly.
Fig 1. Schematic diagram of a cooling water system
There are several important factors that govern the operation of cooling tower:
- The dry-bulb and wet-bulb temperatures of the air
- The temperature of warm water
- The efficiency of contact between air and water in terms of the volumetric mass
transfer coefficient and the contact time between the air and the water
- The uniformity of distribution of the phases within the tower
- The air pressure drop
- The desired temperature of the cooled water
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Guidelines for
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COOLING TOWER SELECTION AND
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ENGINEERING DESIGN GUIDELINES
Page 6 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Air might enter the tower driven by a density gradient (natural draft), might be pushed
into the tower (forced draft) at the base or drawn into the tower (induced draft)
assisted by a fan. Several types of cooling towers have been designed on the basis of
the above factors and operating strategies.
The cooling tower might be classified into several types, but they are broadly
categorized by following considerations:
1. Whether there is direct or indirect contact
2. The mechanism used to provide the required airflow
3. The relative flow paths of air and water
4. The primary materials of construction
5. the type of heat transfer media applied
6. The tower’s physical shape
General classification of cooling tower is pictured below:
Fig 2. Classifications of cooling towers
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Guidelines for
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COOLING TOWER SELECTION AND
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ENGINEERING DESIGN GUIDELINES
Page 7 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Classification by build
Package Type
This type of cooling towers is preassembled and can be simply transported on trucks
as they are compact machines. The capacity of package type towers are limited and
for that reason, they are usually preferred by facilities with low heat rejection
requirements such as food processing plants, textile plants, buildings like hospitals,
hotels, malls, chemical processing plants, automotive factories etc. Due to the
intensive use in domestic areas, sound level control is a relatively more important
issue for package type cooling towers.
Field Erected Type
Field erected type cooling towers are usually preferred for power plants, steel
processing plants, petroleum refineries, and petrochemical plants. These towers are
larger in size compared to the package type cooling towers.
Classification based on heat transfer method
Wet Cooling Tower
This type of cooling tower operates based on evaporation principle. The working fluid
and the evaporated fluid (usually water) are one and the same. In a wet cooling tower,
the warm water can be cooled to a temperature lower than the ambient air dry-bulb
temperature, if the air is relatively dry.
Dry Cooling Tower
This tower operates by heat transfer through a surface that separates the working fluid
from ambient air, such as in a tube to air heat exchanger, utilizing convective heat
transfer. Dry cooling tower does not use evaporation.
Fluid Cooler
This tower passes the working fluid through a tube bundle, upon which clean water is
sprayed and a fan-induced draft applied. The resulting heat transfer performance is
much closer to that of a wet cooling tower, with the advantage provided by a dry
cooler of protecting the working fluid from environmental exposure and contamination.
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Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 8 of 52
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Classification based on air draft
Atmospheric Tower
An atmospheric tower consist of a big rectangular chamber with two opposite louvered
walls. The tower is packed with a suitable tower fill. Atmospheric air enters the tower
through the louvers driven by its own velocity. An atmospheric tower is cheap but
inefficient. Its performance largely depends upon the direction and velocity of wind.
Fig 3. Atmospheric cooling tower
Natural Draft Tower
The natural draft or hyperbolic cooling tower makes use of the difference in
temperature between the ambient air and the hotter air inside the tower. As hot air
moves upwards through the tower (because hot air rises), fresh cool air is drawn into
the tower through an air inlet at the bottom.
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Practical Engineering
Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 9 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
A natural draft tower is so called because natural flow of air occurs through the tower.
Two factors are responsible for creating the natural draft:
- a rise in temperature and humidity of air in the column reduces its density, and
- the wind velocity at the tower bottom.
Due to the layout of the tower, no fan is required and there is almost no circulation of
hot air that could affect the performance. But in some cases, a few fans are installed
at the bottom to enhance the air flow rate. This type of tower is called ‘fan-assisted’
natural draft tower.
The hyperbolic shape is made because of the following reasons:
- more packing can be fitted in the bigger area at the bottom of the shell;
- the entering air gets smoothly directed towards the centre because of the shape of
the wall, producing a strong upward draft;
- greater structural strength and stability of the shell is provided by this shape.
The pressure drop across the tower is low and the air velocity above the packing may
vary from 1-1.5 m/s. The concrete tower is supported on a set of reinforced concrete
columns. Concrete is used for the tower shell with a height of up to 200 m. These
cooling towers are mostly only for large heat duties because large concrete structures
are expensive.
Fig 4 (a) Cross flow and (b) counter flow natural draft cooling tower
10. KLM Technology
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Practical Engineering
Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 10 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Mechanical Draft Cooling Tower
Because of their huge shape, construction difficulties and cost, natural draft towers
have been replaced by mechanical draft towers in many installations. Mechanical draft
towers have large fans to force or draw air through circulated water. The water falls
downwards over fill surfaces, which helps increase the contact time between the water
and the air. Cooling rates of mechanical draft towers depend upon various
parameters; such as fan diameter and speed of operation, fills for system resistance,
etc.
There are two different classes of mechanical draft cooling towers:
a. Forced draft
It has one or more fans located at the tower bottom to push air into the tower.
During operation, the fan forces air at a low velocity horizontally through the
packing and then vertically against the downward flow of the water that occurs on
either side of the fan. The drift eliminators located at the top of the tower remove
water entrained in the air. Vibration and noise are minimal since the rotating
equipment is built on a solid foundation. The fans handle mostly dry air, greatly
reducing erosion and water condensation problems.
Fig 5. Forced draft cooling tower
b. Induced draft
A mechanical draft tower with a fan at the discharge which pulls air through tower.
The fan induces hot moist air out the discharge. This produces low entering and
high exiting air velocities, reducing the possibility of recirculation in which
discharged air flows back into the air intake.
11. KLM Technology
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Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 11 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Fig 6. Induced draft cooling tower
Classification based on air flow pattern
Crossflow
Crossflow is a design in which the air flow is directed perpendicular to the water flow.
Air flow enters one or more vertical faces of the cooling tower to meet the fill material.
Water flows (perpendicular to the air) through the fill by gravity. The air continues
through the fill and thus past the water flow into an open plenum area. A distribution or
hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized
in a crossflow tower. Gravity distributes the water through the nozzles uniformly
across the fill material.
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SIZING
ENGINEERING DESIGN GUIDELINES
Page 12 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Fig 7. Crossflow type design
Counterflow
In a counterflow design the air flow is directly opposite to the water flow (see diagram
below). Air flow first enters an open area beneath the fill media and is then drawn up
vertically. The water is sprayed through pressurized nozzles and flows downward
through the fill, opposite to the air flow.
Fig 8. Counterflow type design
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Guidelines for
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COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 13 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
GENERAL DESIGN CONSIDERATION
Components of A Cooling Tower
Structural Components [1]
Most cooling systems are very vulnerable to corrosion. They contain a wide variety of
metals and circulate warm water at relatively high linear velocities. Both of these
factors accelerate the corrosion process. Deposits in the system caused by silt, dirt,
debris, scale and bacteria, along with various gases, solids and other matter dissolved
in the water all serve to compound the problem. Even a slight change in the cooling
water pH level can cause a rapid increase in corrosion. Open recirculating systems
are particularly corrosive because of their oxygen-enriched environment.
The structural components of cooling tower such as: cold water basin, framework,
water distribution system, fan deck, fan cylinders, mechanical equipment supports, fill,
drift eliminators, casing, and louvers.
1. Cold water basin
The cold water basin has two fundamentally important functions: collecting the cold
water following its transit of the tower, and acting as the tower’s primary
foundation.
2. Tower framework
The most commonly used materials for the framework of field-erected towers are
fiberglass, wood, and concrete, with steel utilized infrequently to conform to a local
building code, or to satisfy a specific preference.
3. Water distribution system
Lines might be buried to minimize problem of thrust loading, thermal expansion
and freezing; or elevated to minimize cost of installation and repair. In either case,
the risers to the tower inlet must be externally supported, independent of the tower
structure and piping.
4. Fan deck
The fan deck is considered a part of the tower structure, acting as a diaphragm for
transmitting dead and live loads to the tower framing. It also provides a platform for
the support of the fan cylinders, as well as an accessway to the mechanical
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Guidelines for
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ENGINEERING DESIGN GUIDELINES
Page 14 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
equipment and water distribution system. Fan deck materials are customarily
compatible with the tower framework.
5. Fan cylinder
Fan cylinder directly affects the proper flow of air through the tower. Its efficiencies
can be severely reduced by a poorly designed fan cylinder, or significantly
enhanced by a well-designed one.
6. Mechanical equipment supports
Customary material for the unitized supports is carbon steel, hot-dip galvanized
after fabrication, with stainless steel construction available at significant additional
cost.
7. Fill (heat transfer surface)
Fill (heat transfer surface) is able to promote both the maximum contact surface
and the maximum contact time between air and water determines the efficiency of
the tower. The two basic fill classifications are splash type and film type.
Splash type fill breaks up the water, and interrupts its vertical progress, by causing
it to cascade through successive offset levels of parallel splash bars. It is
characterized by reduced air pressure losses, and is not conducive to logging.
However, it is very sensitive to inadequate support.
Film type fill causes the water to spread into a thin film, flowing over large vertical
areas, to promote maximum exposure to the air flow. It has capability to provide
more effective cooling capacity within the same amount of space, but is extremely
sensitive to poor water distribution.
8. Drift eliminator
Drift eliminators remove entrained water from the discharge air by causing it to
make sudden changes in direction. The resulting centrifugal force separates the
drops of water from air, depositing them on the eliminator surface, from which they
flow back into the tower.
Eliminator are normally classified by the number of directional changes or
“passes”, with an increase in the number of passes usually accompanied by an
increase in pressure drop.
9. Casing
A cooling tower casing acts to contain water within the tower, provide an air
plenum for the fan, and transmit wind loads to the tower framework. It must have
diaphragm strength, be watertight and corrosion resistant, have fire retardant
qualities, and also resist weathering.
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Page 15 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
10.Louvers
Every well-designed crossflow tower is equipped with inlet louvers, whereas
counterflow towers are only occasionally required to have louvers. Their purpose is
to retain circulating water within the confines of the tower, as well as to equalize air
flow into the fill.
Mechanical Components [1]
1. Fans
Cooling tower fans must move large volumes of air efficiently, and with minimum
vibration. The materials of manufacture must not only be compatible with their
design, but must also be capable of withstanding the corrosive effects of the
environment in which the fans are required to operate.
a. Propeller fans: They have ability to move vast quantities of air at the relatively
low static pressure encountered. They are comparatively inexpensive, may be
used on any size tower, and can develop high overall efficiencies; but their
application naturally tends to be limited by the number of projects of sufficient
size to warrant their consideration.
b. Automatic variable-pitch fans: They are able to vary airflow through the tower in
response to a changing load or ambient condition.
c. Centrifugal fans: They are usually used on cooling towers designed for indoor
installations; their capability to operate against relatively high static pressures
makes them particularly suitable for that type of application. However, their
inability to handle large volumes of air, and their characteristically high input
horsepower requirement limits their use to relatively small applications.
All propeller type fans operate in accordance with common laws:
- The capacity varies directly as the speed ratio, and directly as the pitch angle of
the blades relative to the plane of rotation.
- The static pressure varies as the square of the capacity ratio.
- The fan horsepower varies as the cube of the capacity ratio.
- At constant capacity, the fan horsepower and static pressure vary directly with
air density.
2. Speed reducers
The optimum speed of a cooling tower fan seldom coincides with the most efficient
speed of the driver (motor); thus a speed reduction or power transmission unit is
needed between the motor and the fan.
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Page 16 of 52
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
3. Drive shafts
The driveshafts transmit power from the output shaft of the motor to the input shaft
of gear reduction units.
4. Valves
Valves are used to control and regulate flow through the water lines serving the
tower. Valves utilized for cooling tower application include:
a. Stop valves: They are used on both counterflow and crossflow towers to
regulate flow in multiple-riser towers, and to stop flow in a particular riser for cell
maintenance.
b. Flow-control valves: They are considered to discharge to the atmosphere, and
essentially as the end-of-line valves.
c. Make-up valves: These are valves utilized to automatically replenish the normal
water losses from the system.
Electrical Components [1]
1. Motors
Electric motors are used almost exclusively to drive the fans on mechanical draft
cooling towers, and they must be capable of reliable operation under extremely
adverse conditions.
2. Motor controls
Motor controls serve to start and stop the fan motor and to protect it from overload
or power supply failure, thereby helping assure continuous reliable cooling tower
operation. They are not routinely supplied as a part of the cooling tower contract
but, because of their importance to the system, the need for adequate
consideration in the selection and wiring of these components cannot be
overstressed.
3. Wiring system
The wiring system design must consider pertinent data on the available voltage (its
actual value, as well as its stability), length of lines from the power supply to the
motor, and the motor horsepower requirements.
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Tower materials
Originally, cooling towers were constructed primarily with wood, including the frame,
casing, louvers, fill and cold-water basin. Sometimes the cold-water basin was made
of concrete. Today, manufacturers use a variety of materials to construct cooling
towers. Materials are chosen to enhance corrosion resistance, reduce maintenance,
and promote reliability and long service life. Galvanized steel, various grades of
stainless steel, glass fiber, and concrete are widely used in tower construction, as well
as aluminum and plastics for some components.
1. Frame and casing
Wooden towers are still available, but many components are made of different
materials, such as the casing around the wooden framework of glass fiber, the inlet
air louvers of glass fiber, the fill of plastic and the cold-water basin of steel. Many
towers (casings and basins) are constructed of galvanized steel or, where a
corrosive atmosphere is a problem, the tower and/or the basis are made of
stainless steel. Larger towers sometimes are made of concrete. Glass fiber is also
widely used for cooling tower casings and basins, because they extend the life of
the cooling tower and provide protection against harmful chemicals.
2. Fill
Plastics are widely used for fill, including PVC, polypropylene, and other polymers.
When water conditions require the use of splash fill, treated wood splash fill is still
used in wooden towers, but plastic splash fill is also widely used. Because of
greater heat transfer efficiency, film fill is chosen for applications where the
circulating water is generally free of debris that could block the fill passageways.
3. Nozzles
Plastics are also widely used for nozzles. Many nozzles are made of PVC, ABS,
polypropylene, and glass-filled nylon.
4. Fans
Aluminum, glass fiber and hot-dipped galvanized steel are commonly used as fan
materials. Centrifugal fans are often fabricated from galvanized steel. Propeller
fans are made from galvanized steel, aluminum, or molded glass fiber reinforced
plastic.
18. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 18 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Cooling Tower Design Consideration
Once a tower characteristic has been established between the plant engineer and the
manufacturer, the manufacturer must design a tower that matches the value. The
required tower size will be a function of:
1. Cooling range
2. Approach to wet bulb temperature
3. Mass flow rate of water
4. Wet bulb temperature
5. Air velocity through tower or individual tower cell
6. Tower height
Other design characteristics to consider are fan horsepower, pump horsepower,
make-up water source, fogging abatement, and drift eliminator.
Operation Considerations
1. Water make-up
Water losses include evaporation, drift (water entrained in discharge vapor), and
blowdown (water released to discard solids). Drift losses are estimated to be
between 0.1 and 0.2% of water supply.
2. Cold weather operation
Even during cold weather months, the plant engineer should maintain the design
water flow rate and heat load in each cell of the cooling tower. If less water is
needed due to temperature changes (i.e. the water is colder), one or more cells
should be turned off to maintain the design flow in the other cells.
The water in the base of the tower should be maintained between 60 and 70o
F by
adjusting air volume if necessary. Usual practice is to run the fans at half speed or
turn them off during colder months to maintain this temperature range.
Improving Energy Efficiency of Cooling Towers
The most important options to improve energy efficiency of cooling towers are:
1. Follow manufacturer’s recommended clearances around cooling towers and
relocate or modify structures that interfere with the air intake or exhaust
2. Optimize cooling tower fan blade angle on a seasonal and/or load basis
19. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 19 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
3. Correct excessive and/or uneven fan blade tip clearance and poor fan balance
4. In old counter-flow cooling towers, replace old spray type nozzles with new square
spray nozzles that do not clog
5. Replace splash bars with self-extinguishing PVC cellular film fill
6. Install nozzles that spray in a more uniform water pattern
7. Clean plugged cooling tower distribution nozzles regularly
8. Balance flow to cooling tower hot water basins
9. Cover hot water basins to minimize algae growth that contributes to fouling
10.Optimize the blow down flow rate, taking into account the cycles of concentration
(COC) limit
11.Replace slat type drift eliminators with low-pressure drop, self-extinguishing PVC
cellular units
12.Restrict flows through large loads to design values
13.Keep the cooling water temperature to a minimum level by (a) segregating high
heat loads like furnaces, air compressors, DG sets and (b) isolating cooling towers
from sensitive applications like A/C plants, condensers of captive power plant etc.
Note: A 1o
C cooling water temperature increase may increase the A/C compressor
electricity consumption by 2.7%. A 1o
C drop in cooling water temperature can give
a heat rate saving of 5 kCal/kWh in a thermal power plant
14.Monitor approach, effectiveness and cooling capacity to continuously optimize the
cooling tower performance, but consider seasonal variations and side variations
15.Monitor liquid to gas ratio and cooling water flow rates and amend these
depending on the design values and seasonal variations. For example: increase
water loads during summer and times when approach is high and increase air flow
during monsoon times and when approach is low.
16.Consider COC improvement measures for water savings
17.Consider energy efficient fibre reinforced plastic blade adoption for fan energy
savings
18.Control cooling tower fans based on exit water temperatures especially in small
units
19.Check cooling water pumps regularly to maximize their efficiency
20. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 20 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Tower Problems
By their very design, open recirculating cooling systems are prime candidates for
contamination problems. As the cooling water evaporates, contaminants are allowed
to concentrate in the system. Contaminants enter the system either through the
makeup water or from the air via the cooling tower. If left untreated, high
concentrations of impurities in open recirculating systems can lead to a number of
serious problems, including:
1. Scale
The most serious side effect of scale formation is reduced heat transfer efficiency.
Loss of heat transfer efficiency can cause reduced production or higher fuel cost. If
heat transfer falls below the critical level. the entire system may need to be shut
down and cleaned. Unscheduled downtime can obviously cost thousands of dollars
in lost production and increased maintenance. Once scale becomes a serious
threat to efficiency or continued operation, mechanical or chemical cleaning is
necessary.
In most cases, mineral scale is a silent thief of plant profitability. Even minute
amounts of scale can provide enough insulation to affect heat transfer and
profitability severely.
Scale in cooling water systems is mainly composed of inorganic mineral
compounds such as calcium carbonate (which is most common), magnesium
silicate, calcium phosphate and iron oxide. These minerals are dissolved in the
water, but if left to concentrate uncontrolled, they will precipitate. Scale occurs first
in heat transfer areas but can form even on supply piping. Many factors affect the
formation of scale, such as the mineral concentration in the cooling water, water
temperature, pH, availability of nucleation sites (the point of initial crystal formation)
and the time allowed for scale formation to begin after nucleation occurs.
Dissolved mineral salts are inversely temperature soluble. The higher the
temperature, the lower their solubility. The most critical factors for scale formation
are pH, scaling ion concentration and temperature. Consequently, most open
recirculating systems operate in a saturated state. because the scaling ions are
highly concentrated. Precipitation is prevented under these conditions by the
addition of a scale inhibitor.
2. Fouling
Waterborne contaminants enter cooling systems from both external and internal
sources. Though filtered and clarified, makeup water may still hold particles of silt.
clay, sand and other substances. The cooling tower constantly scrubs dirt and dust
21. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 21 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
from the air, adding more contaminants to the cooling water. Corrosion by-
products, microbiological growth and process leaks all add to the waterborne
fouling potential in a cooling system.
The solids agglomerate as they collide with each other in the water. As more and
more solids adhere, the low water velocity, laminar flow, and rough metal surfaces
within the heat exchangers allow the masses of solids to settle out, deposit onto
the metal. and form deposits. These deposits reduce heat transfer efficiency,
provide sites for underdeposit corrosion, and threaten system reliability.
Waterborne fouling can be controlled by a combination of mechanical and
chemical programs
3. Microbiological growth
Cooling water systems are ideal spots for microscopic organisms to grow. "Bugs"
thrive on water, energy and chemical nutrients that exist in various parts of most
cooling water systems. Generally, a temperature range of 70-1 40º F (21-60 o
C)
and a pH range of 6-9 provide the perfect environment for microbial growth.
Bacteria, algae and fungi are the most common microbes that can cause serious
damage to cooling water systems. Microbiological fouling can cause:
- Energy losses
- Reduced heat transfer efficiency
- Increased corrosion and pitting
- Loss of tower efficiency
- Wood decay and loss of structural integrity of the cooling tower
4. Corrosion
Corrosion is the breakdown of metal in the presence of water, air and other metals.
The process reflects the natural tendency of most manufactured process metals to
recombine with oxygen and return to their natural (oxide) states. Corrosion is a
particularly serious problem in industrial cooling water systems because it can
reduce cooling efficiency, increase operating costs, destroy equipment and
products and ultimately threaten plant shutdown.
Most cooling systems are very vulnerable to corrosion. They contain a wide variety
of metals and circulate warm water at relatively high linear velocities. Both of these
factors accelerate the corrosion process. Deposits in the system caused by silt,
dirt, debris, scale and bacteria, along with various gases, solids and other matter
dissolved in the water all serve to compound the problem. Even a slight change in
the cooling water pH level can cause a rapid increase in corrosion. Open
recirculating systems are particularly corrosive because of their oxygen-enriched
environment.
22. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 22 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Table 1. Typical Problems and Trouble Shooting for Cooling Towers
Problem/ Difficulty Possible Causes Remedies/Rectifying Action
Excessive absorbed
current/electrical load
1. Voltage Reduction Check the voltage
2a.Incorrect angle of axial fan blades Adjust the blade angle
2b.Loose belts on centrifugal fans (or speed
reducers)
Check belt tightness
3. Overloading owing to excessive air flow-
fill has minimum water loading per m
2
of
tower section
Regulate the water flow by
means of the valve
4. Low ambient air temperature The motor is cooled
proportionately and hence
delivers more than name plate
power
Drift/carry-over of
water outside the unit
1. Uneven operation of spray nozzles Adjust the nozzle orientation
and eliminate any dirt
2. Blockage of the fill pack Eliminate any dirt in the top of
the fill
3. Defective or displaced droplet eliminators Replace or realign the
eliminators
4. Excessive circulating water flow (possibly
owing to too high pumping head)
Adjust the water flow-rate by
means of the regulating valves.
Check for absence of damage
to the fill
Loss of water from
basins/pans
1. Float-valve not at correct level Adjust the make-up valve
2. Lack of equalising connections Equalise the basins of towers
operating in parallel
Lack of cooling and
hence increase in
temperatures owing
to increased
temperature range
1. Water flow below the design valve Regulated the flow by means of
the valves
2. Irregular airflow or lack of air Check the direction of rotation of
the fans and/or belt tension
(broken belt possible)
3a. Recycling of humid discharge air Check the air descent velocity
3b. Intake of hot air from other sources Install deflectors
4a. Blocked spray nozzles (or even blocked
spray tubes)
Clean the nozzles and/or the
tubes
4b. Scaling of joints Wash or replace the item
5. Scaling of the fill pack Clean or replace the material
(washing with inhibited aqueous
sulphuric acid is possible but
long, complex and expensive)
23. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 23 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
DEFINITIONS
ACFM – The actual volumetric flow rate of air-vapor mixture.
Air Horsepower – The power output developed by a fan in moving a given air rate
against a given resistance.
Air inlet – Opening in a cooling tower through which air enters. Sometimes referred to
as the louvered face on induced draft towers.
Air rate – Mass flow of dry air per square foot of cross-sectional area in the tower’s
heat transfer region per hour.
Air travel – Distance which air travels in its passage through the fill. Measured
vertically on counterflow towers and horizontally on crossflow towers.
Air velocity – Velocity of air-vapor mixture through a specific region of the tower (i.e.
the fan).
Ambient wet-bulb temperature – The wet bulb temperature of the air encompassing
a cooling tower, not including any temperature contribution by the tower itself.
Generally measured upwind of a tower, in a number of locations sufficient to account
for all extraneous sources of heat.
Approach – Difference between the cold water temperature and either the ambient or
entering wet-bulb temperature.
Atmospheric – Refers to the movement of air through a cooling tower purely by
natural means, or by the aspirating effect of water flow.
Automatic variable-pitch fan – A propeller type fan whose hub incorporates a
mechanism which enables the fan blades to be re-pitched simultaneously and
automatically. They are used on cooling towers and air-cooled heat exchangers to trim
capacity and/or conserve energy.
24. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 24 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Basin curb – Top level of the cold water basin retaining wall; usually the datum from
which pumping head and various elevations of the tower are measured.
Bay – The area between adjacent transverse and longitudinal framing bents.
Bent – A transverse or longitudinal line of structural framework composed of columns,
grid, ties, and diagonal bracing members.
Blowdown – Water discharged from the system to control concentrations of salts and
other impurities in the circulating water.
Blower – A squirrel-cage (centrifugal) type fan; usually applied for operation at higher-
than-normal static pressures.
Brake Horsepower – The actual power output of a motor, turbine, or engine.
Btu (British thermal unit) – The amount of heat gain (or loss) required to raise (or
lower) the temperature of one pound of water 1o
F.
Capacity – The amount of water (gpm) that a cooling tower will cool through a
specified range, at a specified approach and wet-bulb temperature.
Casing – Exterior enclosing wall of a tower, exclusive of the louvers.
Cell – Smallest tower subdivision which can function as an independent unit with
regard to air and water flow; it is bounded by either exterior walls or partition walls.
Each cell may have one or more fans and distribution systems.
Circulating water rate – Quantity of hot water entering the cooling tower.
Cold water temperature – Temperature of the water leaving the collection basin,
exclusive of any temperature effects incurred by the addition of make-up and/or the
removal blowdown.
25. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 25 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Collection basin – Vessel below and integral with the tower where water is transiently
collected and directed to the sump or pump suction line.
Counterflow – Air flow direction through the fill is counter-current to that of the falling
water.
Crossflow – Air flow direction through the fill is essentially perpendicular to that of the
falling water.
Cycles of concentration (C.O.C) – The ratio of dissolved solids in circulating water to
the dissolved solids in make up water.
Distribution basin – Shallow pan-type elevated basin used to distribute hot water
over the tower fill by means of orifices in the basin floor. Application is normally limited
to crossflow towers.
Distribution system – Those parts of a tower, beginning with the inlet connection,
which distribute the hot circulating water within the tower to the points where it
contacts the air for effective cooling. May include headers, laterals, branch arms,
nozzles, distribution basins and flow-regulating devices.
Double flow - A crossflow cooling tower where two opposed fill banks are served by
a common air plenum.
Drift – Circulating water lost from the tower as liquid droplets entrained in the
exhausted air stream.
Drift eliminator – An assembly of baffles or labyrinth passage through which the air
passes prior to its exit from the tower, for the purpose of removing entrained water
droplets from the exhaust air.
Driver – Primary device for the fan drive assembly. Although electric motors
predominate, it may also be a gas engine, steam turbine, hydraulic motor or other
power source.
26. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 26 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Dry-bulb temperature – The temperature of the entering or ambient air adjacent to
the cooling tower as measured with a dry-bulb thermometer.
Entering wet-bulb temperature – The wet-bulb temperature of the air actually
entering the tower, including any effects of recirculation. In testing, the average of
multiple readings taken at the air inlets to establish a true entering wert-bulb
temperature.
Evaluation – A determination of the total cost of owning a cooling tower for a specific
period of time. Includes first cost of tower and attendant devices, cost of operation,
cost of maintenance, cost of financing, etc., all normalized to a specific point in time.
Evaporation loss – Water evaporated from the circulating water into the air stream in
the cooling process.
Fan cylinder – Cylindrical or venturi-shaped structure in which a propeller fan
operates.
Fan deck – Surface enclosing the top structure of an induced draft cooling tower,
exclusive of the distribution basins on a crossflow tower.
Fan pitch – The angle which the blades of a propeller fan make with the plane of
rotation, measured at a prescribed point on each blade.
Fan scroll – Convolute housing in which a centrifugal (blower) fan operates.
Fill – That portion of a cooling tower which constitutes its primary heat transfer
surface.
Fill cube – (1) Counterflow: the amount of fill required in a volume one bay long by
one bay wide by an air travel high. (2) Crossflow: The amount of fill required in a
volume one bay long by an air travel wide by one story high.
Fill deck – One of a succession of horizontal layers of splash bars utilized in a splash-
fill cooling tower. The number of fill decks constituting overall fill height, as well as the
27. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 27 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
number of splash bars incorporated within each fill deck, establishes the effective
primary heat transfer surface.
Fill sheet – One of a succession of vertically-arranged, closely-spaced panels over
which flowing water spreads to offer maximum surface exposure to the air in a film-fill
cooling tower. Sheets may be flat, requiring spacers for consistent separation; or they
may be formed into corrugated, chevron, and other patterns whose protrusions
provide proper spacing, and whose convolutions provide increased heat transfer
capability.
Float valve – A valve which is mechanically actuated by a float. Utilized on many
cooling towers to control make-up water supply.
Flow-control valves – Manually controlled valves which are used to balance flow of
incoming water to all sections of the tower.
Flume – A through which may be either totally enclosed, or open at the top. Flumes
are sometimes used in cooling towers for primary supply of water to various sections
of the distribution system. Flumes are also used to conduct water from the cold water
basins of multiple towers to a common pumping area or pump pit.
Fogging – A reference to the visibility and path of the effluent air stream after having
exited the cooling tower. If visible and close to the ground, it is referred to as “fog”. If
elevated, it is normally called the “plume”.
Forced draft – Refers to the movement of air under pressure through a cooling tower.
Fans of forced draft towers are located at the air inlets to “force” air through the tower.
Heat load – Total heat to be removed from the circulating water by cooling tower per
unit time.
Height – On cooling towers erected over a concrete basin, height is measured from
the elevation of the basin curb. “Nominal” heights are usually measured to the fan
deck elevation, not including the height of the fan cylinder.
28. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 28 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Hot water temperature – Temperature of circulating water entering the cooling tower
by means of an induced partial vacuum. Fans of induced draft towers are located at
the air discharges to “draw” air through the tower.
Interference – The thermal contamination of a tower’s inlet air by an external heat
source (i.e. the discharge plume of another cooling tower).
Leaving wet-bulb temperature – Wet-bulb temperature of the air discharge from a
cooling tower.
Length – For crossflow towers, length is always perpendicular to the direction of air
flow through the fill (air travel), or from casing to casing. For counterflow towers, length
is always parallel to the long dimension of a multi-cell tower, and parallel to the
intended direction of cellular extension on single-cell towers.
Liquid-to-gas ratio – A ratio of total mass flows of water and dry air in a cooling
tower.
Longitudinal – Pertaining to occurrences in the direction of tower length.
Louvers – Blade or passage type assemblies nstalled at the air inlet face of a cooling
tower to control water splashout and/or promote uniform air flow through the fill. In the
case of film-type crossflow fill, they may integrally molded to the fill sheets.
Make-up – Water added to the circulating water system to replace water lost by
evaporation, drift, windage, blowdown, and leakage.
Mechanical draft – Refers to the movement of air through cooling tower by means of
a fan or other mechanical devices.
Module – A preassembled portion or section of a cooling tower cell. On larger factory-
assembled towers, two or more shipping modules may require joining to make a cell.
Natural draft – Refers to the movement of air through a cooling tower purely by
natural means. Typically, by the driving force of a density differential.
29. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 29 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Net effective volume – That portion of total structural volume within which the
circulating water is in intimate contact with the flowing air.
Nozzle – A device used for controlled distribution of water in cooling tower. Nozzles
are designed to deliver water in a spray pattern either by pressure or gravity flow.
Partition – An interior wall subdividing the tower into cells or into separate fan plenum
chambers. Partitions may also be selectively installed to reduce windage water loss.
pH – A scale for expressing acidity or alkalinity of the circulating or make-up water. A
pH below 7.0 indicates acidity and above 7.0 indicates alkalinity. A pH 7.0 indicates
neutral water.
Pitot tube – An instrument that operates on the principle of differential pressures. Its
primary use on a cooling tower is in measurement of circulating water flow.
Plenum chamber – The enclosed space between the drift eliminators and the fan in
induced draft towers, or the enclosed space between the fan and the fill in forced draft
towers.
Plume – The effluent mixture of heated air and water vapor (usually visible) discharge
from a cooling tower.
Psychrometer – An instrument incorporating both a dry-bulb and a wet-bulb
thermometer, by which simultaneous dry-bulb and wet-bulb temperature readings can
be taken.
Range – Difference between the hot water temperature and the cold water
temperature (HW-CW).
Recirculation – Describes a condition in which a portion of the tower’s discharge air
re-enters the air inlets along with the fresh air. Its effect is an elevation of the average
entering wet-bulb temperature compared to the ambient.
30. KLM Technology
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Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 30 of 52
Rev: 01
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These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Riser – Piping which connects the circulating water supply line, from the level of the
base of the tower or the supply header, to the tower’s distribution system.
Shell – The chimney-like structure, usually hyperbolic in cross-section, utilized to
induced air flow through a natural draft tower.
Speed reducer – A mechanical device, incorporated between the driver and the fan of
a mechanical draft tower, designed to reduce the speed of the driver to an optimum
speed of the fan.
Splash bar – One of a succession of equally-spaced horizontal bars comprising the
splash surface of a fill deck in a splash-filled cooling tower. Splash bar may be flat, or
may be formed into shaped cross-section for improved structural rigidity and/or
improved heat transfer capability.
Splash fill – Descriptive of a cooling tower in which splash type fill is used for the
primary heat transfer surface.
Spray fill – Descriptive of a cooling tower in which has no fill, with water-to-air contact
depending entirely upon the water break-up and pattern afforded by pressure spray
nozzles.
Stack – An extended fan cylinder whose primary purpose is to achieve elevation of
the discharge plume.
Stack effect – Descriptive of the capability of a tower shell or extended fan cylinder to
induce air (or aid in its induction) through a cooling tower.
Standard air – Air having a density of 0.075 lb/cuft. Essentially equivalent to 70o
F dry
air at 29.92 in Hg barometric pressure.
Story – The vertical dimension between successive levels of horizontal framework
ties, girts, joists, or beams. Story dimensions vary depending upon the size and
strength characteristic of the framework material used.
31. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 31 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
Sump – A depressed chamber either below or along-side (but contiguous to) the
collection basin, into which the water flows to facilitate pump suction. Sump may also
designed as collection points for silt and sludge to aid in cleaning.
Total air rate – Total mass flow of dry air per hour through the tower.
Total water rate – Total mass flow of water per hour through the tower.
Tower pumping head – The static lift from the elevation of the basin curb to the
centerline elevation of the distribution system inlet; plus the total pressure (converted
to ft of water) necessary at that point to effect proper distribution of the water to its
point of contact with the air.
Transverse – Pertaining to occurrences in the direction of tower width.
Velocity recovery fan cylinder – A fan cylinder on which the discharge portion is
extended in height and outwardly flared. Its effect is to decrease the total head
differential across the fan, resulting in either an increase in air rate at constant
horsepower, or a decrease in horsepower at constant air rate.
Water loading – Circulating water rate per horizontal square foot of fill plan area of
the cooling tower.
Water rate – Mass flow of water per square foot of fill plan area of the cooling tower
per hour.
Wet-bulb temperature – The temperature of entering or ambient air adjacent to the
cooling tower as measured with a wet-bulb thermometer.
Wet-bulb thermometer – A thermometer whose bulb is encased within a wetted
wick.
Windage – Water lost from the tower because of the effects of wind.
Wind load – The load imposed upon a structure by a wind blowing against its surface.
32. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 32 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
NOMENCLATURE
a contact area, ft2
/ft3
tower volume
B base area, ft2
cp heat capacity of water, Btu/lbo
F
F air flow rate, ft3
/min
G air flow rate, lb/h
h enthalpy of air stream, Btu/lb
ha enthalpy of air-water vapor mixture at wet-bulb temperature, Btu/lb dry air
a
ah specific enthalpy of dry air, kJ/kg
hs specific enthalpy of saturated mixture, kJ/kg dry air
hw enthalpy of air-water vapor mixture at bulk water temperature, Btu/lb dry air
h’ enthalpy of saturated air at water temperature, Btu/lb
H humidity of an air-water vapor mixture, kg of H2O/kg of dry air or lb of H2O/lb
of dry air
Hp head of pump, ft
HP percentage humidity, %
HR percentage relative humidity, %
HS saturation humidity
K air mass-transfer coefficient, lb water/(h.ft2
)
Ka volumetric air mass transfer constant, lb water/(h.ft3
)
L
VKa
tower characteristic, lb air/lb H2O
L water flow rate, lb/(h.ft2
)
L Loading factor, lb H2O/h
P power, hp
PT total pressure (101.325 kPa, 760 mmHg, or 1.0 atm)
R range (T1 – T2), o
F
pA partial pressure of water vapor in the air
pAS partial pressure of the pure water at the given temperature
Ps pressure of water vapor at saturation, N/m2
ss specific entropy of saturated mixture, J/K·kg dry air
33. KLM Technology
Group
Practical Engineering
Guidelines for
Processing Plant Solutions
COOLING TOWER SELECTION AND
SIZING
ENGINEERING DESIGN GUIDELINES
Page 33 of 52
Rev: 01
July 2011
These design guideline are believed to be as accurate as possible, but are very general and not for specific design
cases. They were designed for engineers to do preliminary designs and process specification sheets. The final
design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will
greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines
are a training tool for young engineers or a resource for engineers with experience.
This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied,
reproduced or in any way communicated or made accessible to third parties without our written consent.
T1 inlet-water temperature, °F
T2 outlet-water temperature, °F
t2 outler-air temperature, o
F
V total fill volume, ft3
Va specific volume of dry air, m3
/kg
Vs specific volume of saturated mixture, m3
/kg dry air
V specific fill volume, ft3
/ft2
Wd drift loss
Wb blowdown [consistent units, m3
/(h.gal.min)]
Wm makeup water
Ws humidity ratio at saturation, mass of water vapor associated with unit mass of
dry air
Z fill height, ft
∆h1 value of (hw - ha) at T2 + 0.1(T1 - T2)
∆h2 value of (hw - ha) at T2 + 0.4(T1 - T2)
∆h3 value of (hw - ha) at T1 - 0.4(T1 - T2)
∆h4 value of (hw - ha) at T1 - 0.1(T1 - T2)
L/G water-air flow rate ratio, lb H2O/lb air
η fan efficiency, dimensionless (~0.80)
ρ density, lb/ft3