Process Technology Equipment Chapter 12 Cooling Towers
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CHAPTER 12 Cooling Towers
Table of Contents
Contents
Page
Chapter Overview
2
Class Preparation Checklist
2
Chapter Objectives
2
Agenda
4
Lesson Plan
5
12.1 Purpose of Cooling Towers
12.2 Components
7
9
12.3 Principles of Operation
10
12.4 Potential Problems
12.5 Safety and Environmental Hazards
12.6 Process Technician’s Role in Operation and
Maintenance
11
13
14
Summary and Wrap-Up
16
Suggested Student Activities
17
End of Chapter Review Questions
17
Clicker Questions
Appendix
26
30
Process Technology Equipment Chapter 12 Cooling Towers
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CHAPTER 12 Cooling Towers
Chapter Overview
Cooling towers usually flow water over internal components made of plastic or wood.
These internal components are designed to break the water into tiny droplets, thereby
increasing surface area and promoting maximum water-to-air contact. Many different
types of cooling towers are in use today. While their designs differ, they all have similar
components and use the same principles of heat transfer.
The main purpose of cooling towers is to remove heat from process cooling water so
the water can be recycled and recirculated through the process. Cooling towers reduce
the temperature of water via heat exchangers and other devices through convection and
evaporation. Cooling tower water can be supplied from municipal water systems or from
other bodies of water, such as rivers or cooling ponds.
Cooling towers can be designed as either open circuit (wet) or closed circuit (dry).
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
12.1 Identify the purpose, applications, and common types of cooling towers (NAPTA
Cooling Towers).
12.2 Identify the components of cooling towers and explain their purpose (NAPTA
Cooling Towers).
12.3 Describe the operating principles of cooling towers (NAPTA Cooling Towers).
12.4 Identify potential problems associated with cooling towers (NAPTA Cooling
Towers).
12.5 Describe safety and environmental hazards associated with cooling towers
(NAPTA Cooling Towers).
Process Technology Equipment Chapter 12 Cooling Towers
12.6 Describe the process technician’s role in typical procedures associated with
cooling towers (NAPTA Cooling Towers).
Process Technology Equipment Chapter 12 Cooling Towers
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Class Agenda
Activity
Minutes
PPTs
Handouts
(title, if
any)
1. Welcome to Class
1
2. Introduction and Agenda
2
3. Safety Minute
3
4. Objectives
4
5. Objectives (cont.)
5
6. Terms
6
7. Terms (cont.)
7
8. Purpose of Cooling Towers
8
9. Types of Cooling Towers
9
10. Natural Draft
10
11. Induced Draft
11
12. Forced Draft
12
13. Closed Circuit
13
14. Applications
14
15. Components
15
16. Principles of Operation
16
17. Principles of Operation (cont.)
17
18. Potential Problems
18
19. Humidity
19
20. Temperature
20
21. Corrosion, Erosion, Fouling, and Scale
21
22. Corrosion, Erosion, Fouling, and Scale (cont.)
22
23. Safety and Environmental Hazards
23
24. Heat Exchanger Tube Leaks
24
25. Fires
25
26. Process Technician’s Role in Operation and
Maintenance
26
27. Component and Concentration Monitoring
27
28. Temperature Monitoring
28
29. Chemical Treatment
29
30. Blowdown
30
31. Maintenance
31
32. Summary and Wrap-Up
32
Process Technology Equipment Chapter 12 Cooling Towers
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Chapter 12 Lesson Plan
Welcome Everyone to Class
Time: 1 minute
Resources: Slide 1
Introduction and Agenda
Time: 2 minutes
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: 1 minute
Resources: Slide 4
Process Technology Equipment Chapter 12 Cooling Towers
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Objectives (cont.)
Time: 1 minute
Resources: Slide 5
Terms
Time: 1 minute
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 minute
Resources: Slide 7
Sample Instructor Script:
More terms that process technicians should be familiar with include the following:
Process Technology Equipment Chapter 12 Cooling Towers
12.1 Purpose of Cooling Towers
Time: 2 minutes
Resources: Slide 8
Sample Instructor Script:
12.1.1 Types of Cooling Towers
Time: 1 minute
Resources: Slide 9
Process Technology Equipment Chapter 12 Cooling Towers
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12.1.2 Natural Draft
Time: 1 minute
Resources: Slide 10
12.1.3 Induced Draft
Time: 1 minute
Resources: Slide 11
12.1.4 Forced Draft
Time: 1 minute
Resources: Slide 12
12.1.5 Closed Circuit
Process Technology Equipment Chapter 12 Cooling Towers
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Time: 1 minute
Resources: Slide 13
12.1.6 Applications
Time: 2 minutes
Resources: Slide 14
12.2 Components
Time: 2 minutes
Resources: Slide 15
Sample Instructor Script:
Although cooling tower designs vary, most are made of plastic and wood and have
similar components.
Process Technology Equipment Chapter 12 Cooling Towers
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• A water distribution system provides returned (hot) cooling water to a distributor
box located at the top of forced and induced draft cooling towers. The water flows
out of the distributor box through a series of nozzles and begins to fall on a set of
splash bars called fill.
• Fill, which consists of slats or splash bars, is the material that breaks the water
into smaller droplets as it falls through the cooling tower. The fill materials direct
the flow of water and maximize the falling path. Breaking the water into smaller
droplets helps increase the surface area of the water. This, coupled with an
increased falling path, facilitates the process of evaporation and increases the
12.3 Principles of Operation
Time: 2 minutes
Resources: Slide 16
Sample Instructor Script:
12.3.1 Principles of Operation (cont.)
Time: 2 minutes
Resources: Slide 17
Sample Instructor Script:
Process Technology Equipment Chapter 12 Cooling Towers
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Water is an excellent cooling medium because it is 50 to 100 times more efficient at
conducting heat than air alone. Lower humidity allows evaporation (latent heat of
vaporization) to make up 80 to 90 percent of the cooling, while sensible heat loss does
the remaining 10 to 20 percent of the cooling.
12.4 Potential Problems
Time: 1 minute
Resources: Slide 18
12.4.1 Humidity
Time: 1 minute
Resources: Slide 19
Sample Instructor Script:
Humidity is the moisture content in the air. Local humidity levels must be considered
when designing a cooling tower because evaporation is much more difficult in areas
with high levels of humidity. For example, a cooling tower in the hot, dry conditions of
Arizona could be significantly smaller than one in the hot, humid climate of south Texas
and still provide the same amount of cooling. The reason evaporation is more difficult in
humid areas is that the ambient air is already partially saturated with moisture, so less
water can be absorbed.
Process Technology Equipment Chapter 12 Cooling Towers
12.4.2 Temperature
Time: 1 minute
Resources: Slide 20
Sample Instructor Script:
Air temperature affects cooling towers by increasing or decreasing the rate of
12.4.3 Corrosion, Erosion, Fouling, and Scale
Time: 2 minutes
Resources: Slide 21
Sample Instructor Script:
12.5.2 Fires
Time: 2 minutes
Resources: Slide 25
Sample Instructor Script:
12.6 Process Technician’s Role in Operation and Maintenance
Time: 2 minutes
Resources: Slide 26
12.6.1 Component and Concentration Monitoring
Time: 2 minutes
Resources: Slide 27
12.6.2 Temperature Monitoring
Time: 2 minutes
Resources: Slide 28
Sample Instructor Script:
12.6.3 Chemical Treatment
Time: 2 minutes
Resources: Slide 29
Sample Instructor Script:
12.6.4 Blowdown
Time: 2 minutes
Resources: Slide 30
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12.6.5 Maintenance
Time: 2 minutes
Resources: Slide 31
Summary and Wrap–Up
Time: 4 minutes
Resources: Slide 32
Sample Instructor Script:
Let’s summarize today’s lesson and consider what we will be doing in the next class.
Process Technology Equipment Chapter 12 Cooling Towers
Suggested Student Activities
1. Given a model or diagram of a cooling tower, identify the components and explain the
purpose of each component.
1. What type of cooling tower has fans at the top of the tower that pull air
through the tower?
A. Natural draft
B. Induced draft
C. Forced draft
D. Open draft
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2. What type of cooling tower has fans or blowers at the bottom of the tower that
force air through the equipment?
A. Natural draft
B. Induced draft
C. Forced draft
D. Open draft
3. In what type of airflow in cooling towers does air and water flow in opposite
directions?
A. Cross-flow
B. Parallel flow
C. Counter-flow
D. Turbulent flow
4. What is the material that breaks the water into smaller droplets as it falls
through the cooling tower?
A. Fill
B. Louvers
C. Drift eliminators
D. Water distribution header