Precautions for the use of closed cooling towers

Precautions for the use of closed cooling towers

1. Requirements for use environment
1. Avoid places with acid gas, explosive dust, severe soot, and excess water vapor;
2. Place next to buildings , should keep a sufficient distance from the air inlet (0.7-3M, depending on the model);
3, placed in the well-type enclosure, should be alert to the heat exhaust failure caused by the return of hot and humid air, special circumstances can consider the draft device ;

Second, piping problems
1. The piping and pump valve should be installed below the operating water level of the cooling tower to prevent overflow and air inhalation;
2. When considering the location of the equipment, it should be With sufficient pump head, the pressure loss along the way and the pressure loss of the cooling coil should be considered; 3. The pressure of the interface flange for fluid cooling is designed to be 1Mpa, and all pipes should be considered for hangers or supports.

Third, consider the compatibility of fluid (gas)
The fluid (gas) that needs to be cooled in a closed-circuit cooling tower (evaporative cooling) must be compatible with the cooling coil, or it will lead to Corrosion or bursting of the coil. For example, the refrigerant ammonia is not compatible with copper pipes, and the brine alkali water is not compatible with carbon steel pipes and copper pipes.

Four. Requirements for spray system
1. With the operation of the closed cooling tower (evaporative cooling), part of the water evaporates, and minerals and other impurities in the water are left and accumulated in the Therefore, the water quality must be checked regularly, and the sewage should be cleaned regularly, which can better control the water quality and prevent scaling. The cleaning of the water tank is generally recommended once a week in summer and once every two weeks in winter; (softening) treatment (for details, please contact our company or ask water treatment experts), if dosing is required, it is best to use stainless steel for the water tank.
3. The supplementary amount of spray water:
Evaporation Volume ≤ 0.8% of flow + drift rate ≤ 0.1% + sewage discharge ≤ 0.3% = ≤ 1.2% of circulating flow
4. One of the following three methods should be considered for the spray system to prevent freezing:
① Set up an indoor thermal insulation water tank, the water tank has enough capacity, and all the spray water can be collected and kept warm when the machine is shut down.
②A heater is installed in the spray tank, generally using an immersed electric heater or a steam coil for heat injection;
③ When the system stops running, drain the spray water.

V. Exhaust

1. Operation of fluid-tight system: copper pipes can be considered as fully enclosed or semi-enclosed as cooling coils; stainless steel or integral hot-dip galvanized pipes as cooling coils must be fully enclosed and supplemented by expansion liquid storage tanks For fluid and gas in the pipe, an automatic exhaust valve can be installed at the highest point of the pipeline. When the gas pressure reaches the set value, the valve opens and the gas is automatically discharged. A manual exhaust device can also be installed with the same effect.

2. It should be noted in the system of the closed cooling tower that the presence of non-condensable gases in the system will significantly reduce the heat exchange effect of the closed cooling tower, so the air discharge operation must be carried out frequently. The pipeline valves connected to the cooling tower are all closed, the air release valve is opened, and part of the air mixture is released without separation through the air separator.

6. Supplementary water
The circulating water of the closed system should meet the water quality requirements of the production process, and can use softened water, demineralized water or condensed water.
7. Antifreeze problem of the cooling coil of the closed cooling tower (very important!)
When the temperature is low in winter in the northern region, the circulating water of the closed system has no heat load, even if the circulating water keeps flowing. The phenomenon of freezing will occur, and proper anti-freezing measures must be taken. Generally, the following two methods should be considered as the most suitable: 1. Keep the circulating water at a certain heat load and ensure that the circulating water temperature is not lower than 5°C (southern region). In order to ensure this heat load, an immersed electric heater or a steam coil can be installed in the piping system to inject heat; at the same time, the circulating water in the closed system can be kept at a minimum flow rate.

2. The most effective method is to add antifreeze, ethylene glycol or propylene glycol, into the closed system. Attention should be paid when filling: the antifreeze effect will not be achieved when the filling is small, and the antifreezing effect will not be achieved when the filling is excessive. It will affect the heat that the medium takes away when it works.

Ø  Ethylene glycol (C2H6O2) solution, the main component of most antifreezes, has the disadvantage of high price. Refer to the following table for antifreeze formula:

Eighth, operating procedures of closed cooling tower

1. Make sure that the switch status of the pump and valve corresponds to normal

2. Make sure that each fan is running normally

3. Make sure the circulating pump and spray pump are working properly

4. Make sure the float valve is working properly

5. Make sure there is no water leakage everywhere in the cooling tower

6. Make sure the water level in the water tank is above the calibration line

7. When the temperature is low (≤5℃), do a good job of heat preservation and antifreeze