Size: 800 Ton Tower
Load: 90% Summer; 30% Winter
Location: Tokyo, Japan
Problem Description: The tower achieved target operating cycles of concentration (CoC) of 7.0 during the summer months. During the winter it was hard to achieve a CoC of >5.0.
Assumption: Cooler temperatures did not enable enough evaporation for tower to “Cycle Up”.
Finding: The calculated summer blowdown rate is 3.6 gallons per minute (GPM) @ 90% load. The calculated winter blowdown rate is 1.2 GPM @ 30% load. Upon inspection a condenser water pump was found with a badly leaking seal (see photo). An impromptu field test was conducted to measure the amount of water being lost through the seal leak. Using a sample bottle to capture the water loss from the pump and a watch to calculate the time it took to fill the bottle it was estimated that just under 2.0 GPM were being lost at the seal.
Conclusion: Water loss through a seal leak has the same effect on a tower that excessive blowdown does. Since the leak rate of 2.0 GPM exceeds the winter blowdown rate of 1.2 GPM it is not possible to achieve the results desired. This problem was not noticed in the summer because the summer blowdown rate of 3.6 GPM exceeds the leak rate of 2.0 GPM.
Load: 90% Summer; 30% Winter
Location: Tokyo, Japan
Problem Description: The tower achieved target operating cycles of concentration (CoC) of 7.0 during the summer months. During the winter it was hard to achieve a CoC of >5.0.
Assumption: Cooler temperatures did not enable enough evaporation for tower to “Cycle Up”.
Finding: The calculated summer blowdown rate is 3.6 gallons per minute (GPM) @ 90% load. The calculated winter blowdown rate is 1.2 GPM @ 30% load. Upon inspection a condenser water pump was found with a badly leaking seal (see photo). An impromptu field test was conducted to measure the amount of water being lost through the seal leak. Using a sample bottle to capture the water loss from the pump and a watch to calculate the time it took to fill the bottle it was estimated that just under 2.0 GPM were being lost at the seal.
Conclusion: Water loss through a seal leak has the same effect on a tower that excessive blowdown does. Since the leak rate of 2.0 GPM exceeds the winter blowdown rate of 1.2 GPM it is not possible to achieve the results desired. This problem was not noticed in the summer because the summer blowdown rate of 3.6 GPM exceeds the leak rate of 2.0 GPM.
Recommendation: Repair seal
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