The topic of Non Chemical Device (NCD) water treatment seems to always be popular. ASHRAE Project Number 1361-RP focused on Biological Control in Cooling Water Systems using Non-Chemical Treatment Devices. Five different NCD devices were analyzed in the study from the following categories: Magnetic, Pulsed Electric Field, Electrostatic, Ultrasonic, and Hydrodynamic Cavitation.
The experiment concluded, "...no statistically significant difference...in planktonic or sessile microbial concentrations (HPC) was observed between the control tower and a tower treated by any of the five NCDs evaluated in this study...", (i-ii).
You can download the entire report here: http://rp.ashrae.biz/page/ASHRAE-D-1361-RP-20101005.pdf
Wednesday, February 29, 2012
Water Treatment Case Study: Low Cycles of Concentration (CoC)
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
Saturday, February 11, 2012
Chiller Inspection
When is the best time of year for selling cooling tower water treatment? It is during the winter months. During the cooler season many clients will begin to do their preventative maintenance on Chillers, Cooling Towers, and Heat Exchangers. It is during this maintenance period that the effects of water treatment will become apparent. When a chiller is opened up for an inspection you want to be there to give your professional opinion. Having a boroscope, digital camera, and a flashlight will assit you in making a quality inspection.
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