UFC 3-240-13FN
25 May 2005
3-6
COMMONLY ASKED QUESTIONS AND ANSWERS ON
BOILER WATER TREATMENT ......................................................
86
CHAPTER 4 COOLING WATER SYSTEMS
Paragraph
4-1
TYPES OF COOLING WATER SYSTEMS.......................................
88
4-1.1
Once-Through Cooling Water Systems .....................................
88
4-1.2
Open Recirculating Cooling Water Systems..............................
88
4-1.3
Types of Cooling Towers ...........................................................
91
4-1.3.1
Natural-Draft Towers .................................................................
91
4-1.3.2
Forced-Draft Towers..................................................................
92
4-1.3.3
Induced-Draft Towers ................................................................
92
4-1.3.4
Typical Cooling Towers at Government Installations.................
94
4-1.4
Components of a Cooling Tower ...............................................
95
4-1.4.1
Basin and Cold Well ..................................................................
95
4-1.4.2
Louvers ......................................................................................
95
4-1.4.3
Fill ..........................................................................................
96
4-1.4.4
Drift Eliminators .........................................................................
96
4-1.4.5
Water Distribution and Fan Deck...............................................
96
4-1.4.6
Cell ..........................................................................................
96
4-1.5
Common Cooling Water System Problems ...............................
97
4-1.5.1
Enhanced and Super-Enhanced Chiller Condenser Tubing......
97
4-1.5.2
White Rust .................................................................................
98
4-1.5.3
Cooling Tower Film Fill ..............................................................
99
4-1.5.4
Legionella Bacteria ....................................................................
99
4-2
COOLING TOWER WATER CALCULATIONS..................................
100
4-2.1
Principles of Cooling Tower System Operations .......................
100
4-2.1.1
Relationship Between Evaporation, Blowdown, and Makeup....
100
4-2.1.2
Cycles of Concentration (COC) .................................................
100
4-2.1.2.1
Calculating COC by Volume ......................................................
101
4-2.1.2.2
Determining COC by Water Analyses........................................
101
4-2.1.2.3
Controlling COC.........................................................................
102
4-2.1.2.4
Relationship Between COC and Makeup ..................................
102
4-2.1.3
Relationship Between Blowdown, Evaporation, and COC.........
103
4-3
OBJECTIVES OF COOLING WATER TREATMENT..........................
105
4-3.1
Deposit Formation and Control..................................................
105
4-3.2
Scale..........................................................................................
105
4-3.2.1
Determining Scaling Potential....................................................
105
4-3.2.2
Calcium Carbonate Scale ..........................................................
106
4-3.2.3
Calcium Phosphate Scale..........................................................
106
4-3.2.4
Calcium Sulfate Scale................................................................
106
4-3.2.5
Silica Scale ................................................................................
107
4-3.3
Determining COC to Control Operations ...................................
107
4-3.4
Calcium Carbonate Scaling Indices...........................................
108
4-3.4.1
Langelier and Ryznar Indices ....................................................
108
4-3.4.2
Practical (Puckorius) Scaling Index (PSI) ..................................
109
4-3.5
Scale Control Methods ..............................................................
109
4-3.5.1
Calcium Carbonate Scale Control Using Solubilizing
Chemicals ..................................................................................
110
4-3.5.1.1
Acids ..........................................................................................
110
4-3.5.1.2
Phosphonates............................................................................
110
4-3.5.2
Calcium Carbonate Scale Control Using Solubilizing
vi
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