Addtime： 2020-07-16 Browse times： 4205
With the beginning of vacuum pump scaling, the heat transfer environment of circulating water in the pump is gradually destroyed, the heat exchange efficiency will be lower and lower, and the scaling speed will be faster and faster. The causes of scale include the following aspects:
1. Thermal decomposition
After the circulating water containing hardness components enters into the vacuum pump, it forms a water ring in the pump body with the rotation of the pump to work and heat, so that the bicarbonate dissolved in the water gradually decomposes, and the precipitation difficult to water forms scale.
vacuum system
2. Solubility decrease
With the increase of circulating water temperature, the solubility of SO4, CaSiO3 and CaCO3 with negative solubility temperature coefficient decreases and precipitates into scale. In the process of vacuum pump operation, salts with high solubility in circulating water react with other salts to form insoluble substances and form scale.
4. Evaporation and concentration
Due to the continuous work and heating of circulating water, evaporation and concentration will inevitably occur, which makes the concentration of dissolved salt in water increase continuously, and precipitate and form scale when reaching saturation.
Causes of scaling in vacuum pump and three methods to prevent scaling
Therefore, it is necessary to reduce the hardness of water as much as possible and control the working temperature of circulating water to solve the scaling problem of vacuum pump.
1. The operation process of circulating water in vacuum pump is very similar to that of boiler water in low pressure hot water boiler. Therefore, according to the water quality standard of hot water boiler to manage the water quality of vacuum pump can not only prevent the vacuum pump from scaling, but also prevent the vacuum pump from corrosion.
Most of the circulating water systems of vacuum pumps are open circulation systems with high backwater rate. In the case that ion exchange equipment is not used for water treatment due to capital and other reasons, a softened water tank and a high water tank are generally used to supply water to the vacuum pump.
2. Temperature control of circulating cooling water from the above analysis, it can be seen that the difference between the water ring temperature in the vacuum pump and the water temperature in the softening pool is an important factor leading to scaling. Therefore, increasing the circulating water supply and improving the cooling effect is an important guarantee to minimize the scaling rate. Therefore, in the process of circulating cooling water operation, it is necessary to monitor the return water temperature and quantity of each pump, so as to ensure the normal water supply of each pump and the return water temperature not exceeding 40.
The water supply can be controlled by valves. If the return water temperature exceeds the specified value, low-temperature cold water should be added or other cooling methods should be used to reduce the temperature of softened water in the softening pool.
3. Periodic flushing of the pump body water ring vacuum pump drainage gate valve, in addition to the normal discharge of water in the pump, but also in the operation of the pump body running water pressure to regularly flush the pump dirt and water slag, on the one hand, can prevent the accumulation of dirt, on the other hand, can also prevent water slag into scale.
The scaling problem of vacuum pump has its complicated formation mechanism, and the correct analysis of water quality index and operation parameters is the key to find out the correct preventive measures. In addition to water temperature control and periodic flushing pump, water treatment is the most important link to prevent the pump from scaling.
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