How to prevent freezing damage of closed cooling tower in northern regions

The cooling tower's heat dissipation capacity is designed and selected according to the hottest weather in summer. In other seasons, especially in winter, the heat dissipation capacity is obviously too large. The outlet water temperature of the cooling tower has little relationship with the ambient temperature, and is mainly affected by the wet bulb temperature, which is much lower than the ambient temperature. Even when the cooling tower is in operation, the ambient temperature is higher than 0℃, and the cooling tower can reduce the water inside the tube to below zero, or even freeze. Cooling tower internal circulation and external circulation water icing, may cause the pipe, cooling copper pipe and other components in the tower rupture, in order to prevent the occurrence of such accidents, winter anti-freezing is particularly important.

In order to prevent the coil in the cooling tower from freezing due to improper operation and affecting the normal production, the following winter anti-freezing scheme is provided for reference:

Part I. Outer circulation anti-freezing

(1)Install an electric water heater to prevent the lower tank from freezing. When installing electric heater, it is recommended to install water level switch, temperature controller and other auxiliary equipment together with automatic control. Prevent electric heater from dry burning or over heating. However, the water disc heater cannot prevent the freezing of water pipes, pumps and water pump channels outside the water disc.

(2) in the exposed outside the lower tank of the external circulation pipe (connected to the sprinkler pump), including all water supply and drainage pipes, pump piping and overflow joints should be wrapped with electric hot wire, and insulation to prevent freezing.

(3) when the machine is shut down for a long time, empty all the circulating water and keep the drain valve of the lower sink open and place the drain valve of the bulk water pump.

Part II. Internal circulation anti-freezing (heat exchanger coil tube)

(1) Add antifreeze, recommended to use industrial glycol, but to consider whether the supporting equipment is allowed to add the substance. The proportion should be adjusted according to the local temperature. Because the freezing point of ethylene glycol solution is low, the solubility in water is large, therefore, ethylene glycol is a very good antifreeze. However, the deficiency of this scheme is that, with the increase of the concentration of ethylene glycol solution, the performance of the cooling tower may be slightly reduced. In summer high temperature weather, it is necessary to empty the ethylene glycol and use clean water.

(2) The anti-freezing device inside the tube. At all times, an auxiliary load should be retained on the coil, so that when the cooling tower stops, the water temperature will not fall below 10℃. For the regular shutdown on the day and night, the heater can be installed on the side of the tube. During the shutdown, the heater on the side of the tube will provide heat to the cooling tower cooling copper pipe to ensure that it will not freeze. In addition, it is recommended that a minimum circulating water volume be maintained in the coil.

(3) The above two schemes are required to increase equipment, such as do not want to increase equipment to prevent freezing, long-term shutdown in winter can be taken to empty the circulating water in the heat pipe. If there is no water outlet on the user's pipeline, our cooling tower has designed a water outlet. When discharging water, please open the cooling tower exhaust valve 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 drainage valve open and placed. This method should only be used in an emergency. The water in the coil should not take long to empty.

(4) other possible energy regulation methods include two-speed motor, variable frequency drive and stop/open fan.

Part III. Matters needing attention when using electric heater:

(1) for the use of electric heater, please install a thermostat, so that the water temperature will not rise to excessive temperature.

(2) in order to prevent empty heating, please confirm whether the heating part of the electric heater is immersed in water before powering on. Water level alarms or detection switches are recommended.

(3) for other use methods of the electric heater, please refer to the "operation manual of cooling tower to prevent freezing of the electric heater" before use.

Part IV. Matters needing attention when using antifreeze:

(1) according to the type and concentration of the non-freezing solution, the performance of the cooling tower may change. Please note when selecting.

(2) due to water leakage and other reasons, the concentration of non-freezing solution will be reduced. Please check the concentration regularly and supplement if necessary.