Improving Energy Efficiency of Cooling Towers
The most important options to improve energy efficiency of cooling towers are:
1. Follow manufacturer’s recommended clearances around cooling towers and relocate or modify structures that interfere with the air intake or exhaust
2. Optimize cooling tower fan blade angle on a seasonal and/or load basis
3. Correct excessive and/or uneven fan blade tip clearance and poor fan balance
4. In old counter-flow cooling towers, replace old spray type nozzles with new square spray nozzles that do not clog
5. Replace splash bars with self-extinguishing PVC cellular film fill
6. Install nozzles that spray in a more uniform water pattern
7. Clean plugged cooling tower distribution nozzles regularly
8. Balance flow to cooling tower hot water basins
9. Cover hot water basins to minimize algae growth that contributes to fouling
10.Optimize the blow down flow rate, taking into account the cycles of concentration (COC) limit
11.Replace slat type drift eliminators with low-pressure drop, self-extinguishing PVC cellular units
12.Restrict flows through large loads to design values
13.Keep the cooling water temperature to a minimum level by (a) segregating high heat loads like furnaces, air compressors, DG sets and (b) isolating cooling towers from sensitive applications like A/C plants, condensers of captive power plant etc.
Note: A 1oC cooling water temperature increase may increase the A/C compressor electricity consumption by 2.7%. A 1oC drop in cooling water temperature can give a heat rate saving of 5 kCal/kWh in a thermal power plant
14.Monitor approach, effectiveness and cooling capacity to continuously optimize the cooling tower performance, but consider seasonal variations and side variations
15.Monitor liquid to gas ratio and cooling water flow rates and amend these depending on the design values and seasonal variations. For example: increase water loads during summer and times when approach is high and increase air flow during monsoon times and when approach is low.
16.Consider COC improvement measures for water savings
17.Consider energy efficient fibre reinforced plastic blade adoption for fan energy savings
18.Control cooling tower fans based on exit water temperatures especially in small units
19.Check cooling water pumps regularly to maximize their efficiency