Process Technology Equipment
Chapter 11 Heat Exchangers
Page 1
CHAPTER 11 Heat Exchangers
Table of Contents
Contents
Page
Chapter Overview
2
Class Preparation Checklist
2
Chapter Objectives
2
Agenda
4
Lesson Plan
5
11.0 Heat Exchangers: Introduction
11.1 Types of Heat Exchangers
7
8
11.2 Heater Exchanger Components
13
11.3 Principles of Operation of Heat Exchangers
11.4 Potential Problems
11.5 Safety and Environmental Hazards
11.6 Process Technician’s Role in Operation and
Maintenance
11.7 Typical Procedures
14
16
17
18
18
Summary and Wrap-Up
21
Suggested Student Activities
21
End of Chapter Review Questions
21
Clicker Questions
Appendix
32
36
Process Technology Equipment
Chapter 11 Heat Exchangers
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CHAPTER 11 Heat Exchangers
Chapter Overview
In the process industries, heat exchangers transfer (exchange) heat from one
substance to another without the two materials physically contacting each other. Heat
exchangers come in a variety of types, with the most common type being the shell-and-
tube exchanger.
The process technician is responsible for understanding the purpose, components, and
safe operation of heat exchangers. While the heat exchanger is not a complicated piece
of equipment, problems do occur, and the process technician must know how to
address them. Since heat exchangers contain hot liquids and a heating medium, it is
essential that the process technician understand and adhere to all related operating and
safety procedures.
Class Preparation Checklist
1.
Familiarize yourself with the chapter content.
2.
Bring cutaways or other hands-on teaching aids if available.
3.
Copy and distribute any fill-in-the-blank handouts for today’s content.
4.
Safety Minute prepared or assigned.
5.
Review the PowerPoint slides associated with this chapter (if used) and
make sure that your computer is correctly set up to navigate the slide deck
smoothly.
6.
Request the appropriate A/V equipment (if needed) and make sure that
your computer is correctly synched with the projector to avoid any delays in
the classroom.
Chapter Objectives
11.1 Identify the purpose, common types, and applications of heat exchangers (NAPTA
Heat Exchangers).
11.2 Identify the components of heat exchangers and the purpose of each (NAPTA
Heat Exchangers).
11.3 Describe the operating principles of heat exchangers (NAPTA Heat Exchangers).
11.4 Identify potential problems associated with heat exchangers (NAPTA Heat
Exchangers).
11.5 Describe safety and environmental hazards associated with heat exchangers
(NAPTA Heat Exchangers).
Process Technology Equipment
Chapter 11 Heat Exchangers
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11.6 Describe the process technician’s role in heat exchanger operation and
maintenance (NAPTA Heat Exchangers).
11.7 Identify typical procedures associated with heat exchangers (NAPTA Heat
Exchangers).
Process Technology Equipment
Chapter 11 Heat Exchangers
Page 4
Class Agenda
Activity
Minutes
PPTs
1. Welcome to Class
1
1
2. Introduction and Agenda
1
2
3. Safety Minute
2
3
4. Objectives
0.5
4
5. Objectives (cont.)
0.5
5
6. Terms
1.5
6
7. Terms (cont.)
1.5
7
8. Heat Exchangers: Introduction
1
8
9. Heat Transfer Overview
2
9
10. Types of Heat Exchangers
0.5
10
11. Double-Pipe Heat Exchangers
1
11
12. Spiral Heat Exchangers
1
12
13. Cold Box Heat Exchangers
1
13
14. Air Cooled Heat Exchangers
1
14
15. Shell-and-Tube Heat Exchangers
2
15
16. Kettle Reboilers
0.5
16
17. Plate-and-Frame Heat Exchangers
1
17
18. Exchanger Applications and Services
2
18
19. Heat Exchanger Components
4
19
20. Principles of Operation of Heat Exchangers
3
20
21. Heat Transfer Coefficients
1
21
22. Types of Flow
3
22
23. What Goes Where? Rules of Thumb for Heat
Exchangers
2
23
24. Potential Problems
0.5
24
25. Consequences of Deviation from Normal
Operation
2
25
26. Safety and Environmental Hazards
2
26
27. Process Technician’s Role in Operation and
Maintenance
1
27
28. Typical Procedures
0.5
28
29. Start-up
3
29
30. Shutdown
1
30
31. General Maintenance Tasks
2
31
32. Summary and Wrap-Up
4
32
Process Technology Equipment
Chapter 11 Heat Exchangers
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Chapter 11 Lesson Plan
Welcome Everyone to Class
Time: 1 minute
Resources: Slide 1
Introduction and Agenda
Time: 1 minute
Resources: Slide 2
Safety Minute
Time: 2 minutes
Resources: Slide 3
(Note to Instructor: Follow this procedure for the Safety Minute.)
• Announce who has responsibility for today’s Safety Minute.
• Have the student present the Safety Minute.
• Announce who is presenting the Safety Minute next class.
Objectives
Time: 0.5 minute
Resources: Slide 4
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Chapter 11 Heat Exchangers
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Objectives (cont.)
Time: 0.5 minute
Resources: Slide 5
Terms
Time: 1.5 minutes
Resources: Slide 6
Sample Instructor Script:
Turn to the terms page in today’s chapter in the textbook. I’ll call on some of you to take
turns reading the term and definition aloud and then using that term in a sentence. We’ll
begin with the following terms:
Terms (cont.)
Time: 1.5 minutes
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Chapter 11 Heat Exchangers
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11.0 Heat Exchangers: Introduction
Time: 1 minute
Resources: Slide 8
Sample Instructor Script:
11.0.1 Heat Transfer Overview
Time: 2 minutes
Resources: Slide 9
Process Technology Equipment
Chapter 11 Heat Exchangers
11.1 Types of Heat Exchangers
Time: 0.5 minute
Resources: Slide 10
Sample Instructor Script:
Process Technology Equipment
Chapter 11 Heat Exchangers
Page 9
11.1.1 Double–Pipe Heat Exchangers
Time: 1 minute
Resources: Slide 11
Sample Instructor Script:
11.1.2 Spiral Heat Exchangers
Time: 1 minute
Resources: Slide 12
11.1.3 Cold Box Heat Exchangers
Time: 1 minute
Resources: Slide 13
Sample Instructor Script:
11.1.4 Air Cooled Heat Exchangers
Time: 1 minute
Resources: Slide 14
Process Technology Equipment
Chapter 11 Heat Exchangers
11.1.5 Shell–and–Tube Heat Exchangers
Time: 3 minutes
Resources: Slide 15
Sample Instructor Script:
A fixed tubesheet type of shell–and–tube heat exchanger uses either single– or multi–
pass arrangements based on the design of the channel heads. The advantage of this
type of exchanger is its low cost. The disadvantage is that design limitations reduce the
temperature differential (ΔT) that the exchanger can handle.
A floating head type of shell–and–tube heat exchanger has the process fluid exit the
tubes at one end and is captured and directed by a head that is not fixed to the shell of
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Chapter 11 Heat Exchangers
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11.1.6 Kettle Reboilers
Time: 0.5 minute
Resources: Slide 16
11.1.7 Plate–and–Frame Heat Exchangers
Time: 1 minute
Resources: Slide 17
Sample Instructor Script:
11.1.8 Exchanger Applications and Services
Time: 3 minutes
Resources: Slide 18
Sample Instructor Script:
Heat exchangers are used to heat or cool process fluids. They can be used alone or
Process Technology Equipment
Chapter 11 Heat Exchangers
A reboiler is a tubular heat exchanger, usually placed near the base of a distillation
column or stripper, which is used to supply necessary column heat. The reboiler boils
the liquid entering it to produce the vapor needed for the distillation column to separate
the product mixture. The control temperature is based on the boiling point of the fluid
being converted to vapor. The heating medium for a reboiler can be steam or hot fluids
from other parts of the facility.
Interchangers use hot process fluids on the tube side and cooler process fluids on the
shell side. Interchangers are often used on columns or towers to preheat the feed to the
column and cool the bottom material.
Chillers (coolers) are devices used to cool a fluid to a temperature below ambient
temperature. Chillers often use refrigerant as a coolant.
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Chapter 11 Heat Exchangers
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11.2 Heat Exchanger Components
Time: 4 minutes
Resources: Slide 19
Sample Instructor Script:
The components of a heat exchanger may vary based on the design and purpose of the
exchanger. However, there are some commonalities among exchangers. For example,
the components of a typical shell–and–tube heat exchanger include the tubes,
tubesheets, segmental baffles, and tie rods that make up the tube bundle.
The exchanger head (also called the channel head) is located on the end of a heat
exchanger and is where the flow of fluids is directed into and out of the tubes.
Finned tubing consists of thin plates of metal that are attached to the outside of a tube
to provide an additional surface area for heat transfer. A car radiator is a typical finned
tube application in everyday life. In the process industries, air–cooled exchangers (fin
fans), air preheaters, and tank heaters often use finned tubes.
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Chapter 11 Heat Exchangers
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11.3 Principles of Operation of Heat Exchangers
Time: 3 minutes
Resources: Slide 20
Sample Instructor Script:
In the process industries, many chemical reactions generate heat or require the addition
of heat. Some of this heat is transmitted to process fluids and must be removed. The
only way to remove heat from a process stream is to transfer it to another process
stream or some other heat-absorbing material.
11.3.1 Heat Transfer Coefficients
Time: 1 minute
Resources: Slide 21
Process Technology Equipment
Chapter 11 Heat Exchangers
Sample Instructor Script:
The overall heat transfer coefficient is a calculated variable that indicates the rate at
11.3.2 Types of Flow
Time: 3 minutes
Resources: Slide 22
Sample Instructor Script:
In a shell-and-tube exchanger, liquids or gases of varying temperatures are introduced
in opposite directions. Because it is the most efficient flow type, most shell-and tube-
exchangers have countercurrent flow design.
Crossflow occurs when two streams move perpendicular to each other. This is
commonly achieved by installing baffles, or dividers, in the shell side of the shell-and-
tube heat exchanger, which direct the flow.
Process Technology Equipment
Chapter 11 Heat Exchangers
11.3.3 What Goes Where? Rules of Thumb for Heat Exchangers
Time: 2 minutes
Resources: Slide 23
Sample Instructor Script:
Which fluid is put on the tube side of a shell–and–tube heat exchanger? While there are
many considerations, these are some of the most common:
11.4 Potential Problems
Time: 0.5 minute
Resources: Slide 24
Sample Instructor Script:
Process Technology Equipment
Chapter 11 Heat Exchangers
11.4.1 Consequences of Deviation from Normal Operation
Time: 2 minutes
Resources: Slide 25
Sample Instructor Script:
For sufficient heat transfer to take place, a specific temperature differential must exist
11.5 Safety and Environmental Hazards
Time: 2 minutes
Resources: Slide 26
Sample Instructor Script:
Hazards associated with normal and abnormal heat exchanger operation can affect
Process Technology Equipment
Chapter 11 Heat Exchangers
Personal protective equipment (PPE) should be worn during normal and abnormal heat
exchanger operations. In addition to basic PPE (gloves, safety shoes, glasses, hardhat,
hearing protection, and flame resistant clothing), additional PPE that may be required
includes:
11.6 Process Technician’s Role in Operation and Maintenance
Time: 1 minute
Resources: Slide 27
11.7 Typical Procedures
Time: 0.5 minute
Resources: Slide 28
Sample Instructor Script:
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Chapter 11 Heat Exchangers
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Process technicians should be aware of typical heat exchanger procedures, which
include monitoring, inspecting for leaks, lockout/tagout, routine and preventive
maintenance, sampling, start-up, shutdown, and emergency procedures. Failure to
perform proper monitoring and follow procedures could affect the process and result in
equipment damage or injury.
11.7.1 Start–up
Time: 3 minutes
Resources: Slide 29
Filling the Low-Temperature Fluid Side
1. Inspect the heat exchanger to see if it is ready for start-up.
2. Verify that all the drains and bleeders are shut and plugged.
3. Establish the cold stream flow to the heat exchanger.
4. Open the cold-side vent valve slightly to allow any trapped vapors to escape;
then slowly crack open the cold-side inlet valve.
5. Shut off the vent valve when the cold side is filled; open the cold-side inlet valve
fully.
6. Slowly open the cold-side outlet valve.
Lining Up the Hot Side
The next step after filling the low-temperature side is to line up the hot side of the
exchanger:
Process Technology Equipment
Chapter 11 Heat Exchangers
11.7.2 Shutdown
Time: 1 minute
Resources: Slide 30
Sample Instructor Script:
11.7.3 General Maintenance Tasks
Time: 2 minutes
Resources: Slide 31
Sample Instructor Script:
General maintenance tasks performed on heat exchangers may include backwashing,