How to prevent freezing in a closed cooling tower in winter?
The heat rejection capacity of the closed cooling tower is designed and selected according to the hottest weather in summer. In other seasons, especially winter, the heat rejection capacity may be too large. When the closed cooling tower is in operation, even if the ambient temperature is higher than zero, the closed cooling tower may drop the water in the pipe to zero or even freeze. The freezing of circulating or spraying water in a closed cooling tower may cause rupture of piping, heat exchange tubes and other components in the tower. In order to prevent such accidents, winter equipment antifreeze, especially in northern areas, is particularly important .
1. Antifreeze spray system (outside the heat exchange tube)
a) Install an electric underwater heater to prevent freezing of the lower water tank. When installing an electric heater, it is recommended to install auxiliary equipment such as water level switch and temperature controller together with automatic control. Prevent the electric heater from burning dry or overheating.
b) At the sprinkler pipe (connected to the sprinkler pump) exposed outside the lower tank, install insulation materials or electric heating cables.
c) When shutting down for a long time, drain all external circulating water. And keep the drain valve of the lower tank and the drain valve of the spray water pump open.
d) When the temperature is low in winter, natural ventilation and cooling of the coil can be considered to drain the spray water.
2. Internal circulation antifreeze (in the heat exchange tube)
a) Add antifreeze. It is recommended to use industrial glycol. An aqueous solution containing 40% ethylene glycol has a freezing point of -25 degrees, and a 60% aqueous solution has a freezing point of -49 degrees. However, adding ethylene glycol may result in a slight decrease in the performance of the closed cooling tower. Therefore, in the hot weather in summer, the design margin of the closed cooling tower should be considered, and if necessary, the glycol solution should be replaced with clean water.
b) Antifreeze unit in the tube. For regular shutdowns such as day-to-day operation and night-time shutdown, an in-pipe bypass electric heater can be installed. When shutting down, the bypass electric heating provides heat to the heat exchange tube of the closed cooling tower to ensure that it does not freeze. This solution will bring about a certain amount of power consumption and must be professionally designed.
c) Drain the circulating water in the heat exchange tube. For units that have been out of service for a long time, be sure to drain the circulating water in the heat exchange tubes. If the user does not have a water outlet, some brands of closed cooling towers have spare water outlets below the inlet and outlet. When discharging water, please open the exhaust port of the closed cooling tower at the same time. If possible, use high-pressure air to force out the circulating water in the pipe. And keep the exhaust valve and drain valve open.
d) For units whose ambient temperature is above zero, an automatic control system can be used to prevent freezing. Monitor the outlet temperature of the cooling tower and the spray water temperature in the sump. When the temperature is lower than a certain temperature, stop the spray water pump; when it is lower than a lower temperature, stop the fan. In this way, the water in the tube can only drop to the ambient temperature at the lowest point, and it will not freeze.
Jiangsu Jincheng Air Conditioning Engineering Co., Ltd. has been focusing on the design, development and production of industrial air conditioning equipment for many years. Its industrial refrigeration is widely used. The main products are: industrial air conditioning, chemical fiber industrial air conditioning, textile industrial air conditioning, chemical fiber industrial refrigeration, and dust-free workshop refrigeration , Ventilation ducts, cooling towers, refrigerators and other air conditioning units and accessories.
Jiangsu Jincheng is a rare conscience manufacturer in the industrial refrigeration industry. If you want to know more product information, please contact: Mr. Song 13705113637 Website: http://q045.cn/