The evaporator circulating cooling water contains a large amount of salt material, corrosion products and various microbes. Due to the lack of water treatment, a large amount of calcium and magnesium carbonate scale and algae, microorganism silt and sticky mud will be formed on the water side after the evaporator has been running for a period of time. These fouling is firmly attached to the inner surface of the copper tube, causing heat transfer evil. The increase of the circulating pressure and the decrease of the vacuum degree of the unit will affect the operation efficiency of the unit and cause great economic losses.
Conventional cleaning methods usually use chemical cleaning acid pickling. This method is effective for all kinds of deposits, and it is less time-consuming than mechanical methods. However, chemical cleaning is corrosive to the system and other metal parts, and is prone to corrosion of equipment and pipelines, and also pollutes the environment when discharging.
Descaling preparation for evaporator
1. Disconnect other systems that have nothing to do with the evaporator.
2, open the evaporator water side high point vent valve and the steam side low point guide valve to ensure that the large amount of gas produced during the cleaning process can be discharged in time and the fullness of the cleaning liquid. At the same time, the leakage of the copper tube in the heat exchanger during the cleaning process is monitored through the guide valve.
3. In order to monitor the cleaning effect of the system and the corrosion of the equipment during the cleaning process, the standard corrosion test pieces and monitoring tubes, which are equivalent to the material of the equipment, are suspended in the cleaning tank before cleaning.
Evaporator maintenance work
1) the leak detection work of the evaporator is often carried out. Leakage is a common fault phenomenon of evaporator, so we should pay attention to leak detection frequently.
When it leaks, it has a pungent odor, and there is no frost at the leak point. The leak can be checked by phenolphthalein test paper, because ammonia is alkaline, and phenolphthalein test paper becomes red. When you look at it, it is usually the place where the evaporator does not froze somewhere, usually it is a leak point, or it can be found in the leak with soap and water.
The leakage of evaporator can be checked by halogen lamp and halogen leak detector, or with soap and water. Check to see if there is an oil trace on the evaporator, because freon and oil can dissolve, when Freon Leone, the oil will also leak out from the leak, so where there is oil, where the leakage. When Leon leak in a halogen lamp, the flame from the halogen lamp from the blue to the micro green, the light green, the green, the purple green, the purple and so on, can judge the amount of Leon leakage. If the flame is dark green or purple, the phosgene in the flame is poisonous and can not be checked with this method for a long time. In this case, soapy water can be used to check the leakage point. For micro leakage, halogen leak detector should be used for leak detection.
2) check the frosting condition of the evaporator often. When the frost layer is too thick, it should be defrosted in time. When frost is abnormal, it may be caused by blockage. We should find out the cause and eliminate it in time.
3) when the evaporator is stopped, the refrigerant will be clumsy to the accumulator or condenser, so that the pressure of the evaporator should be maintained at about 0.05MPa. If it is an evaporator in the salt water tank, it needs to be washed with tap water and filled with tap water after washing.