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description and measures for winter freezing prevention of closed cooling tower equipment

  187  2023/01/05

       the evaporative cooler (closed cooling tower) is to place the heat exchange components (coil or tube bundle) inside the equipment, through the forced convection of the axial flow fan, and the heat exchange of spray water and circulating water to ensure the cooling effect. due to the closed cycle, it can ensure that the water quality is not polluted, can well ensure the efficient operation of the main equipment, and increase its service life. when the outside temperature is low, the spray water system can be stopped to save water. with the implementation of national energy conservation and emission reduction policies and the increasing shortage of water resources, the closed cooling towers produced by our company have been widely used in metallurgy, electric power, petroleum, chemical and other industries.
       the winter temperature in northern areas is usually below zero, and the problem of frost prevention in the operation of closed cooling towers has become increasingly prominent. if it is not solved well, the heat exchange tubes or other parts of the cooling tower may be damaged by freezing. according to the process characteristics of different users, some closed cooling towers run all day in winter, some run for part of the time, and some stop running completely. however, it is necessary to consider the issue of winter equipment antifreeze.
       in response to the above situation, the user is provided with equipment antifreeze requirements and operating specifications:
1. anti-freezing measures for occasions that are basically not used in winter
       if the closed cooling tower does not need to be operated in winter, the spray water and the circulating water inside the heat exchange tube must be drained when it is shut down.
       specific operation sequence:
       ① turn off the power of the axial flow fan and spray water pump successively;
       ② close the equipment inlet valve, open the tube bundle vent and drain sealing cover, connect the dn32 water pipe to the tube bundle drain pipe to introduce the water in the tube bundle into the water tank, then close the water tank replenishment valve, open the drain valve to empty the water tank, and turn on the spray water pump the drain outlet drains the water in the pump body;
       ③ open the bottom line plug of each pipe pass, and use high-pressure air to drain the residual water in the pipe;
       ④ install the wire plug to the equipment, and cover the tube bundle to vent and drain.
       (for a closed cooling tower with a flexible coil structure, when it is out of service, open the inlet and outlet valves of the equipment to drain the medium in the pipe)
2. antifreeze measures for occasions during operation
       as the equipment load becomes smaller in winter, for a system with multiple equipment running in parallel, the fans and pumps of some equipment should be disabled, and the internal heat exchange tube (not less than 80% of the design flow) should be kept running; the antifreeze of a small circulating water system can be considered add ethylene glycol solution; adding antifreeze can solve the problem at one time without worries.
       ethylene glycol solution is the main component of most antifreeze liquids. refer to the following table for antifreeze formula:
ethylene glycol(wt%) 0 10 20 30 40 50 58 80 90 100
freezing point(c) -0.0 -3.5 -8 -15 -24 -36 -48 -47 -59 -63
antifreeze of spray water system:
       for equipment with electric heaters, it is generally turned on when the spray water is lower than 5°c, and stopped when the spray water is above 8°c. the temperature probe transmits the signal to the control cabinet to automatically control the start and stop of the electric heater.
       for equipment where the sprinkler pump is turned on and prepared, the flange of the upper water pipe on the side of the deactivated pump should be sealed with a flange cover or the spare water pump should be removed to ensure that there is no water in the water pipe on the side of the deactivated;
specific operation sequence:
       ①turn off the power of the spray pump first;
       ②put the upper water pipe butterfly valve to the fully open position, and then remove the pvc water connection pipe on the side of the disabled pump;
       ③choose a suitable flange cover (usually dn125 for the upper water pipe flange) to close the deactivated side;
       ④turn on the sprinkler pump to be used and check whether the water flange on the side of the stop is leaking. if the water leaks, tighten the flange bolts or replace the sealing gasket.
3. anti-freezing measures for occasions of year-round operation
       if the equipment works uninterruptedly, antifreeze is not required. when the ambient temperature is between 0℃ and -5℃, antifreeze measures must be taken when the machine is shut down for more than 10 hours. when the ambient temperature is between -5℃ and -10℃, antifreeze measures must be taken when the machine is shut down for more than 5 hours. measures: when the ambient temperature is lower than -10°c, anti-freezing measures must be taken when the machine stops for more than 1 hour. the specific anti-freezing measures can refer to the anti-freezing measures of some operating occasions.
       please use our company's closed cooling tower for frost protection according to your company's specific situation. if you have any questions or special circumstances, please contact our company's after-sales department, and we will provide you with quality services.