Cooling Towers |
Types of cooling towers
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Two types of cooling towers
1.Direct contact evaporative cooling tower (Open circuit heat exchangers)
2.Indirect contact evaporative cooling tower (Closed circuit heat exchanger)
*Cooling towers are used to dissipate heat from water cooled refrigeration systems and can economically cool condencor water down with 5 to 10 degrees farienhiet of ambient
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Thermal capacity of cooling towers determined by: |
Entering + leaving water temp 95-85
Entering wet bulb temp 78 F
Water flow rate 3 GPM/ tonn
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Fill material |
This material is used to increase surface area for heat exchange. There are two types:
1.Splash type
-Wood
-Plastic (Horizontal open)
2.Film type
-PVC (vertical closed)
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Water treatment for cooling towers |
Evaporation in direct or indirect tower applications results in a concentration of dissolved solids in the circulating water. This concentration is held with in limits by wasting water through an overflow or blow down
*Bleed off rate = approx. 2 gallons/ hour/ ton
*Additional water treatment may be required
-Chemical feed pumps= automatically
-Addition of required chemical (Manually)
Fill material is very susceptible to various types of deposits causing scaling and fouling leading to biological growth on the fill
-Wood fill = Worst
-Plastic fill = Best
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Corrosion And Scale Deposits |
Cooling towers as well as evaporative condensers are exposed to many atmospheric conditions such as:
-Industrial smoke
-Chemical fumes
-Salt air
-Heavy dust
In addition to
-Water quality
-Galvanic action
The deposits left from the above sources are the main reason of:
-Corrosion
-High Algae growth
-Scaling
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Corrosion And Scale Control |
Bleed off (Approx 2 GPM/ ton)
Chemical Treatment
Micro mate plates (Controlled Use) comfort air systems
Blend of phosphates and various polymers (keeps deposits in suspension)
PH levels normally maintained between 7.5 and 8.5
-Below 7 = Acidic add castic soda or alkaline
- 7 = Neutral
-Above 7 = Add sulpheric acid
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Algae & Bacteria Control |
-Chemical treatment
-Use algaecides or Bactericides (chlorine)
*Chemical type may be often changed as algae and bacteria adapts treatment
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