Maintenance of cooling tower components

16-04-2019

Maintenance of cooling tower components


Cooling Tower


Operation record

When the cooling tower is built or installed and put into operation, the design unit or manufacturer shall provide all the characteristic data of the cooling tower: including thermal characteristics, resistance characteristics, water load, heat load, ambient temperature (dry and wet bulb temperature), and cooling range. , air flow rate, power consumption, wind blow loss, evaporation water volume, supplementary water volume, concentration ratio, fan power consumption, water pressure into the tower, etc., the relevant responsible department of the user should make a record of operation according to the above contents.


2. Measuring instruments and methods

In order to check the cooling effect of the cooling tower, or to evaluate the cooling capacity, it is necessary to conduct an indoor test study or an identification test of the running cooling tower at the production site. Therefore, not only must there be scientific and technical personnel in the cooling tower test research, but also have a complete set of relatively complete and standard test methods, and must be equipped with a set of test instruments and instruments (some have spare), such as thermometers, anemometers, micro Pressure gauges, pressure gauges, sound level meters, etc., see the chapter "Cooling Tower Tests".


3. Cooling water collection basin

The cold water collecting basin should maintain the water depth of the pool to prevent cavitation. The freeboard height of the collecting pool is 15~30cm. The following is the effective volume of the pool. The water level of the pool should be maintained at a certain level. Otherwise, the supplementary water valve should be adjusted. For cross-flow cooling towers, if the operating water level is lower than the design requirements, air baffles should be installed below the original water surface to prevent air bypass. The cold water pool should be cleaned occasionally to remove the sludge and adhesive deposited on the bottom of the pool, remove the debris dropped by the packing and its support, keep the grille of the water pump suction port clean, and check the leak of the collecting pool from time to time, such as When repairing is required, it is necessary to pay attention to whether the acid, chlorine, and water quality stable drug dispensing devices are operating normally.

The amount of supplemented water and the amount of sludge discharged are closely related to the water quality control of the circulating water. The dosage should be adjusted in time according to the requirements of the system.


4. Hot water distribution system

In order to keep the hot water distribution system clean and smooth, including regulating valves, voltage regulators, water distribution pipes, nozzles, splashers, and adjusting the water flow in each tank in the distribution tank, the water depth is obtained (the water depth is 100-150cm). If there is a big change in the amount of circulating water entering the tower, the water distribution pipe and nozzle should be adjusted accordingly.


5. Fan and its transmission

Fan and drive shaft: Regularly check the surface of the fan blade for damage or abnormality. When checking the drive shaft and coupling, keep a straight line.

Gear reducer: Regularly check the oil level and oil temperature in the gear reducer, and use seasonal temporary parking to exchange oil and check various parts. Motor: The motor is the same as the fan and reducer, and must be lubricated and maintained according to the maintenance requirements of the relevant manufacturer. For example, the motor with the second gear should have a delay of at least 20 minutes after the high-speed coil is de-energized and before the low-speed coil is powered. In order to eliminate the extreme stress of the shifting, when changing the direction of rotation, there is at least 2 min delay before the fan and motor are powered.


6. The pool produces foam

At the beginning of the new tower operation, a large amount of foam is easily generated in the collecting tank. After a relatively short operation time, the foam generally decreases, so that all disappear. However, sometimes the concentration of some dissolved solids in the water increases, the air dissolves in the surface of the water or foam, or the circulating water and foam produce foam compounds, the cleaning method can be used or the emission can be increased (increasing the number of discharges or prolonging the discharge time) ) to reduce permanent foam. However, in some cases, chemicals and defoamers that inhibit foam must be added to the system.


7. Winter operation

Ice can cause deformation and damage to the water-filling device and cause an accident. Cooling tower freezing often occurs first when cold air entering the cooling tower is in contact with less water. At the air inlet, water flows down the inner wall of the tower to form an icicle, and then freezes into a dense ice curtain to seal the entire air inlet. When the air inlet forms an ice curtain, the amount of air entering the cooling tower is drastically reduced, and the water temperature in the tower rises. In addition, severe freezing on the watering device can cause dangerous vibrations in the tower structure. Internal icing is dangerous, only to be discovered after the sprinkler has been destroyed. Therefore, thermal and hydraulic loads are not allowed to fluctuate during the winter, cooling water must be evenly distributed within the sprinkler system, and the drenching density is not allowed to be reduced in individual locations.

In order to prevent the cooling tower from freezing a lot, it is necessary to periodically or periodically remove the ice from the cooling tower inlet or reduce the cold air entering the cooling tower. The lower the inlet air temperature, the smaller the heat load in the tower and the smaller the amount of air should be. If the intake air volume is properly adjusted so that the temperature of the cooling water in the tower is not lower than 12 to 15 °C, the cooling tower is generally not frozen and does not exceed the allowable limit.

To reduce the amount of cold air entering the cooling tower, it is possible to use a method of closing the fan, or reducing the speed to change the operation of the fan, or reducing the installation angle of the blade. In addition, in order to adjust the wind speed, a shutter can be installed at the air inlet of the tower.

In order to "thaw" the cooling tower, the frozen ice is removed, and the fan can be periodically reversed, so that hot air is blown from the water spraying device to the inlet of the tower to melt the ice of the cooling tower.

In order to alleviate the freezing phenomenon of the inlet of the large (multi-grid) mechanical ventilation cooling tower, various sprinklers have been promoted, including special slit nozzles; it is also possible to supply only the partial water to the partial grid, and completely stop the other compartments. Water can sometimes be used to reduce the amount of circulating water.

In order to prevent icing of the air inlet louver of the cross-flow mechanical ventilation cooling tower, the short pipe or nozzle of the end row of water distribution devices can be properly turned off in winter, and the upper part of the louver can be closed.

Under the condition that the fan works, the possibility of icing of the fan itself is ruled out because of the water collector and the rising hot air. However, when the fan in the cooling tower compartment is turned off, the steam is condensed on the surface to form ice, and then covered by ice formed by the condensed water. In this case, the ice must be removed and the water removed to heat the cooling tower before the fan is re-operated.

In the winter when the cooling tower is not running, in order to avoid freezing on the foundation, the collecting basin should be filled with water and ensure the water circulation in the pool; the cooling tower inlet should be tightly sealed. For those cooling tower tanks that stop running in winter, you can use a small amount of water to drain the sewer to ensure the circulation of water.

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