MIL-HDBK-1003/7
Number of Water Passes. A single pass condenser is commonly used where the
7.2.7
water is supplied from natural sources such as rivers or oceans. If the source of
circulating water is at all limited, a two pass condenser will probably be the best
selection since a single pass condenser requires more cooling water per square foot of
condenser surface and per kilowatt of electrical generation. Usually, a two pass
condenser is used with cooling towers or a cooling lake. Plant layout and orientation
with respect to cooling water source may also dictate the use of a two pass condenser.
If sufficient water is available, the most economical condenser is a single pass. A
single pass condenser is normally smaller in physical size than the equivalent two pass
unit. Typical condenser sizes and cooling water flows for a given turbine generator
capacity are given in Table 15.
Table 15
Typical Condenser Size and Cooling Water Flow
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* Turbine
*
Condenser Surface
Cooling Water
Tube
Tube
*
* Generator Kw
2
ft
Gpm
Length
O.D.
*
*
Single
Two
Single
Two
Feet
Inch
*
*
Pass
Pass
Pass
Pass
*
*
* 5,000
*
3,836
5,147
6,607
4,433
20
3/4
* 7,500
*
5,754
7,721
9,911
6,650
20
3/4
* 10,000
*
7,096
9,522
12,223
8,201
20
3/4
* 20,000
*
12,728
17,079
21,924
14,701
20
3/4
* 30,000
*
18,486
24,637
32,301
21,525
24
7/8
* 40,000
*
24,071
33,290
36,051
24,929
28
7/8
* 50,000
*
30,704
43,211
42,921
30,202
30
7/8
* 60,000
*
34,705
46,889
57,205
38,645
30
1
* 80,000
*
38,706
52,295
63,800
43,100
30
1
*100,000
*
48,180
65,096
79,418
53,650
30
1
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Note: Based on use of Admiralty tubes, 85 degrees F (29.4 degrees C) cooling water
inlet, 2-1/2 inch Hg Abs. condensing pressure, 85 percent cleanliness factor, 6.5 ft/sec
tube water velocity, and 18 BWG tube wall thickness.
Tube Cleanliness Factor. Design tube cleanliness can vary from 70 to 95
7.2.8
percent depending on tube water velocity, cooling water cleanliness, and cooling water
scale-formation characteristics. As condenser tubes become dirty, the heat transfer
coefficient is reduced and the condenser vacuum is decreased. When the cooling water is
clean or is chlorinated, a factor of 0.85 is normally used. For bad water conditions, a
lower value should be used. If the cooling water conditions are very good, a value of
0.90 or 0.95 could be used. For a cooling tower system with stainless steel condenser
tubes, it is practical to use a value of 0.90. For a cooling tower system with
Admiralty condenser tubes, a tube cleanliness factor of 0.85 should probably be used
because of lower tube water velocities through the tubes. In general, with all types of
cooling water (river, ocean, lake, cooling tower) a factor of 0.85 is commonly used for
copper alloy tubes and 0.90 is commonly used for stainless steel tubes.
101
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