NEWS CENTER
Oasis Iceberg
01
2024
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06
Closed-circuit cooling tower heat exchanger maintenance
The water accumulated inside the spray water tank needs to be replaced promptly. Since the closed cooling tower relies on water evaporation to absorb the latent heat of vaporization to reduce the temperature of the fluid inside the pipes, the spray water will continuously evaporate. The scale ions will continuously concentrate, and their concentration will increase. Once it exceeds saturation, crystallization will occur, attaching to the heat exchange tubes, the inner walls of the spray water tank, the spray pump, and the inside of the pipes. This buildup will increase over time, affecting the cooling effect. Over time, the cooling capacity decreases and eventually fails to meet production requirements. In severe cases, the heat exchange coils will have to be replaced, causing significant waste of funds and time.
During the use of closed cooling towers, careful observation and timely maintenance are necessary to ensure cooling efficiency, operational safety, and extended service life. Attention should be paid to the heat exchanger tubes:
1. Mechanism of heat exchanger tube scaling and solutions
Cause: The water accumulated inside the spray water tank needs to be replaced promptly. Since the closed cooling tower relies on water evaporation to absorb latent heat of vaporization to lower the temperature of the fluid inside the tubes, the spray water will continuously evaporate, causing scale ions to concentrate and increase in concentration. Once it exceeds saturation, crystallization occurs and deposits on the heat exchanger tubes, the inner walls of the spray water tank, spray pumps, and inside pipelines, increasing deposits and affecting cooling efficiency. Over time, cooling capacity decreases and eventually fails to meet production requirements. In severe cases, the heat exchanger coils must be replaced, resulting in significant financial and time losses.
Treatment: Clean the spray water tank weekly and replace the water quality to artificially reduce concentration. Although troublesome, this method is simple, reliable, and effective. The bottom water tank of the Oasis Ice Peak equipment is labeled "Spray water tank, clean weekly" to remind managers and operators to pay attention and clean regularly.
2. Impact on cooling efficiency
The heat energy in a closed cooling tower is dissipated from the fluid inside the tubes through the tube walls. External spray water forms a water film on the outer tube walls, which evaporates into gas. The water absorbs latent heat of vaporization as it changes from liquid to gas, carrying away heat, which is then expelled from the tower by the fan.
The heat transfer coefficient is determined by factors such as tube material, tube thickness, scaling coefficient, convection coefficient, wind speed, inlet air temperature, and air humidity. The larger the heat transfer coefficient, the better the cooling effect. After scaling, the scaling coefficient is affected, effectively adding a thick insulating layer on the outer tube wall, greatly reducing heat transfer performance. This reduces heat transfer outward, preventing the internal fluid's heat from being fully discharged in time, causing the cooling effect to fall short of design expectations and increasing outlet water temperature. In severe cases, it cannot meet production process requirements.
3. Treatment methods after scaling
1) For mild scaling, acid cleaning can be used. Since Ice Peak closed cooling towers use copper tubes to improve heat transfer performance, copper reacts chemically with acid:
Cu + H2SO4 = CuSO4 + H2
Therefore, during acid cleaning, the concentration must be properly proportioned to prevent copper tube corrosion and leakage; cleaning time must be reasonably controlled; specific operations require communication with chemical raw material suppliers to explain that the interior contains both copper and carbon tubes to determine the appropriate ratio and cleaning time.
2) For severe scaling, heat exchanger tubes can be disassembled and placed in air for less than 8 hours, then carefully scraped and tapped with wooden scrapers or small hammers to remove hardened scale flakes. Ice Peak closed towers are designed with maintenance convenience in mind, scientifically optimized structurally. After opening the front tube port of the heat exchanger, the tower shell at the rear can be opened to extract the heat exchanger coil. After cleaning, carefully reinstall and seal with sealant, tightening screws securely.
3) For very severe scaling, only replacing the heat exchanger coil is possible, which is costly, inefficient, and time-consuming.
Oasis Bingfeng Fluid Equipment Co.,Ltd
Contact Phone:+86 4000 616 676
Fax:+86 0310 3178005
E-mail:sales@hdbingfeng.com
Contact Address:No.1, Happiness Road, Feixiang Economic Development Zone, Handan City, Hebei Province
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