Shaft seals are used to prevent liquid leakage between the shaft of the compressor or other fluid delivery equipment and the bearings. Measures are taken to ensure the tightness of the vacuum system from the adjustment of the operation of the vacuum unit. It is closely related to the quality of the installation and also meets the operational management level of the operating personnel.
Many factors in the operation of the vacuum unit will affect the vacuum tightness, which is mainly manifested in the shaft seal pressure, the shaft seal heater water level, and the shaft seal two leakage. Determine the optimum shaft seal pressure. The shaft seal pressure is too large, the gap is too small, the shaft seal is heated, and the shaft seal is too small; the shaft seal pressure is too small, the gap is too large, and the shaft seal leakage is too large, which also affects the working efficiency of the vacuum unit.
In order to ensure the optimal shaft seal pressure of the vacuum unit operation, the shaft seal steam supply pressure formed by the self-sealing of the lowest steady-state load and high-load shaft seal system is 45kpa, which satisfies the low-pressure seal shaft seal pressure and minimizes the water intake in the oil. . Monitor the water level of the shaft seal heater. When an abnormality occurs, adjust it in time to ensure that the shaft water level is normal. The shaft is added with no water or the water level is too low, resulting in a decrease in vacuum tightness.
In order to further improve the vacuum degree of the vacuum unit, try to achieve the following requirements:
1. Use the repair and overhaul opportunities of the unit to carry out key inspections on the low-pressure shaft seal, including installation clearance and shaft seal tooth wear. Replace if necessary. The shaft seal pressure is too large, the gap is too small, the shaft seal is heated, and the shaft seal is too small; the shaft seal pressure is too small, the gap is too large, and the shaft seal leakage is too large, which also affects the working efficiency of the vacuum unit.
2. Technical transformation of low-pressure shaft seal supply and return steam drainage system. For the low-pressure front and rear shaft seal supply and the steam return hydrophobic system, if the U-type water seal is not provided, the U-type water seal should be added. The choice of U-shaped water seals must be reasonable to ensure the normal operation of the shaft seal hydrophobic system under various abnormal conditions.
Everything is not absolute. The size of the shaft seal pressure of the vacuum unit directly affects the degree of vacuum. The shaft seal is a sealing device that prevents leakage at the pump shaft and the casing. In order to ensure the life of the vacuum unit sealing device and reduce the leakage of the vacuum unit, the pump inlet pressure should be limited for the pump with dynamic sealing, namely: Ps<10%Pd; Ps——pump inlet pressure, Mpa; Pd— - Pump outlet pressure, Mpa.