| Source Newsletter 2007 issue 1 |
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Non-contact Cooling Water
Quick test
A quick test to see if you are using too much cooling water is to feel the inflow pipe and feel the outflow pipe. Do you feel a noticeable change in temperature?
If no, you are probably using too much water and should investigate further. |
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You may have the opportunity to reduce water use and cost if you have not evaluated your facility’s use of non-contact cooling water. Non-contact, or single-pass, cooling water efficiently carries heat away from high temperature areas to maintain effective operating temperatures for equipment, such as air compressors, presses and x-ray processors.
Reducing water use
Check your use of non-contact cooling water against the list below. If your system meets any one of these criteria, you have flagged a possible opportunity to reduce water use.
- The wastewater temperature is not significantly warmer than the incoming water.
- Water is turned on and left on.
- No flow rate specifications. Water valve is left wide open or set at the operator’s discretion.
- Water goes to drain.
Set flow levels. Understand the need for cooling. Are you protecting equipment, tooling, operating fluids, or something else? Know the safe range for operating temperatures and set flow specifications to match those parameters.
Install controls to set flows. Eliminate operator guesswork by installing flow controls.
Reusing water
Non-contact cooling water is ideal for water reuse if process demands match supply. Before reusing or recycling water, be sure it meets your water quality requirements and identify any treatment steps that may be needed. Reuse opportunities are better if non-contact cooling water can be segregated from other wastewater streams.
Domino’s Pizza—ammonia compressor cooling
To reduce the cost of an impending sewer service availability charge (SAC), Domino’s Pizza Distribution Center changed from single-pass cooling of compressors in its refrigeration system to a closed-loop system that recirculates water through a holding tank. During the winter, the water is cooled sufficiently just circulating through the holding tank. The rest of the year, water is circulated from the tank through an evaporative cooling tower to provide additional cooling. On the hottest days of the year, half of the contents of the storage tank will be drained and refilled with cool city water to maintain appropriate cooling water temperatures. Closed looping this system eliminated 2,400 gallons per day of single-pass flow, saving $3,400 a year in water and sewer charges. The company avoided an $11,000 SAC.
Hibbing Fabricators—spot welder cooling
Hibbing Fabricators uses water to cool two large spot welders, which run four hours a day on average. When the equipment was not in use, water was too often left running. To reduce water use, the company fabricated a 180-gallon water reservoir and interlocked a circulating pump with the spot welder power-supply to automatically trigger the cooling water on and off. The company estimates closed looping has reduced water use by at least 116,000 gpy, saving $570 a year.
For assistance with reducing your non-contact cooling water call MnTAP at 612.624.1300. See the fact sheet Non-contact Cooling Water for more information.
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