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Find How Your Cooling Tower Can Save or Cost You Energy

October
29
2015


Cooling tower costs giving you the heebie jeebies? Halloween is almost here, and many of us will go to a haunted house where we expect things to jump out at us because that's what we pay for! However, when planning for your 2016 cooling costs, startling situations like this should be kept to a minimum. Here are some tips for your cooling tower that can help you save energy, time and money.



WATER

Water flow and water quality are huge contributors to either saving or costing you money. Analyzing how to increase your cooling tower capacity will help improve energy usage and lower cooling costs. To maximize cooling tower capacity there are three things to determine when it comes to water.


  • First your water flow rate (calculated as gallons per minute or GPM's) should be operating at maximum performance.
  • Second, to be able to maximize your water flow rate your cooling tower basin and water distribution systems need to be as clean as possible and free from debris. Dirt and debris filled water will clog nozzles, contribute to fill build up and slow the water rate down.
  • Third, when parts get clogged water will not be evenly distributed thus disrupting the heat transfer process which lowers the cooling capacity and leads to higher costs in energy use.

Save some time and energy yourself by calculating your water usage for your cooling tower so you can quickly determine where capacity improvements can be made.



DRIFT

Drift is another performance issue that needs to be watched closely. Drift is the water lost from your cooling tower due to evaporation through your drift eliminators. The drift rate is calculated as a percentage of the amount of circulating water being lost, measured as pounds of water per million pounds of exhaust air. When water gets lost through the air stream that passes through your drift eliminators of your cooling tower, it is lost forever. Too much water loss means that your drift rate is high and this affects your tower performance. Your tower will require more water to operate instead of keeping the maximum amount of water possible inside of your cooling tower to recirculate and maintain cooling capacity. Calculating your drift rate is important in determining if your drift rate is too high. The amount of acceptable drift loss can vary depending on weather and geographical location however the average drift rate is .002% but a drift rate of .0005% can be achieved. To do so, speak with a cooling tower expert has there are multiple variables to consider in helping you achieve a .0005% drift rate. Also, replace any cracked or brittle drift eliminators as quickly as possible to help achieve minimal drift loss. Need help determining your drift rate? Check out this article "What does Drift Rate Mean?" By Brentwood Industries and one of our trusted vendors.




MECHANICAL OPERATIONS

Your gearbox is the heart of your cooling tower, and without a properly functioning heart your cooling tower cannot operate at its peak performance. Your gearbox can make or break the total cost of energy, time and money. Because your gearbox operates all the mechanics of your cooling tower you must maintain oil lubrication and drive shaft alignment. If your gearbox is operating efficiently less energy will be exerted to operate your fan. Therefore the smoother your fan runs, the better your cooling capacity and the lower your cooling costs will be.





Maintaining your gearbox is fairly simple and does not take up much time compared to the down time and loss of revenue you may experience if your gearbox were to fail. To keep your gearbox happy be sure to always check and change your oil every 2500 hours or every 6 months. Also analyze your oil to determine the amount of water or other contaminations. Lastly check your drive shaft alignment. For detailed information on gearbox operations and maintenance, look at the Gearbox Handbook.





How do fan operations save you energy? When your fans run under minimal vibration and proper alignment you can gain higher fan speeds with less resistance. Higher fan speeds will increase the amount of air flow per square foot of a cross sectional area thereby aiding in your towers heat transfer performance. This increases overall cooling tower capacity thus saving energy. When checking fan performance it is important to determine if there is any fan vibration or decrease in speed performance.



The best way to stay aware of fan vibration issues is to monitor the fan with a vibration switch. The vibration switch is set up to shut the fan off in case of excessive vibration. These switches can be added to your tower for a very minimal cost. A vibration switch will save your maintenance team time and your organization money compared to the cost of failure which includes tower down time and likely mechanical and structural replacements.



To determine fan speed performance inspect the blade pitch, blade tracking, blade sweep, and fan imbalance. Lastly, check to see if there is any debris that may be causing issues. Use the fin fan check worksheet to help fix your system vibration issue.



In conclusion, the three simplest ways to determine if your tower is performing at maximum capacity is to first calculate your water flow rate and inspect your nozzles and water distribution system for clogging. Second, calculate your drift rate. Speak with a cooling tower expert who can help guide you in determining if your drift rate is too high based on the location of your cooling tower. A higher than average drift rate could also be due to cracked or brittle DE's. You will want to inspect your drift eliminators as well. Lastly, maintain your cooling tower mechanics (gearbox, fan, motor) to save energy and improve your cooling tower capacity and performance. Be sure to check your oil monthly and check fan vibrations. A couple of calculations and a little bit of proper maintenance will go a long way toward saving your cooling tower a lot of energy, and your business unnecessary time and money.


 
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