The more widely used in the petroleum, chemical, pharmaceutical, metallurgical and other industries vacuum evaporation, crystallization, distillation, sublimation, drying, vacuum concentration, dehydration, chemical reaction absorption and vacuum conveying materials and other processes, a variety of processes using vacuum technology After the energy saving, speed up the reaction, improve product quality, increase economic efficiency also gradually formed a consensus, but the vacuum technology is a science edge, China's vacuum industry is the digestion and absorption after the liberation of the former Soviet Union, the United States, Japan, Germany products Developed on the basis of. Steam jet vacuum pump with high vacuum, low energy consumption, stable operation, no mechanical friction and long life, equipment safety and so on. In systems with high vacuum requirements, steam jet vacuum pumps are often the preferred vacuum pumping equipment. Based on years of production, development and supporting experience, this article makes a comprehensive analysis of the influencing factors of steam jet vacuum pump and puts forward some solutions to provide some references for its better application. 1, several concepts on the vacuum pump in the industrial production process how to apply a good vacuum pump, you need to be clear about the following concepts: (1) "vacuum" concept: "vacuum" is less than one in a given space Atmospheric pressure of the gas state, that is, the gas molecules in the space density is lower than the atmospheric pressure of gas molecules in the region. The state of space without gas is called absolute vacuum. (2) vacuum pump: is used to produce, improve and maintain the vacuum device. (3) the amount of exhaust: vacuum pump at work pressure per unit time pumping gas flow. Unit: kg / h or m3 / h (4) Ultimate pressure (degree of vacuum): The absolute pressure that the vacuum pump can achieve with a zero extraction volume. Unit: Pa, kPa, MPa or mmHg (the ultimate pressure minus the local atmospheric pressure is the ultimate vacuum) (5) Working pressure (vacuum): Jet pump rated suction absolute pressure. Unit: Pa, kPa, MPa or mmHg (Working pressure minus the local atmospheric pressure for the work of vacuum) (6) Working steam pressure: steam jet vacuum pump working steam pressure. Unit: MPa (7) Working steam consumption: steam jet vacuum pump steam consumption per unit time. Unit: kg / h (8) Cooling water temperature: water jet pump circulating water temperature or steam jet vacuum pump condenser circulating water temperature. Unit: ℃ (9) Cooling water circulation volume: circulating water flow through water ejector or steam jet pump condenser per unit time. Unit: kg / h 2, the structure and working principle of steam jet pump As the name suggests, steam jet vacuum pump working medium is steam. Its working principle can be described as: High-speed steam into the jet pump nozzle, the nozzle is a small hole, the cross-sectional area is small, and thus the formation of high-speed airflow, jet pump cavity, the super-high-speed airflow to the pump cavity negative The pressure and working system are connected to the pump chamber by a line so that non-condensable gases in the working system are constantly being pumped into the pump chamber to achieve a vacuum in the working system. 3, the main factors affecting the steam jet vacuum pump 3.1, steam quality (steam pressure and steam dryness) In the production practice we found that the quality of steam (steam pressure and steam dryness) is good or bad, the vacuum pump vacuum pumping ability And vacuum stability has a great impact. Low steam pressure and uneven pressure have a great impact on the capacity of the vacuum pump. However, due to the structural design of the vacuum pump has been established, the steam pressure is too high and will not increase the amount of suction and vacuum, so the steam pressure should be> 1.1MPa , 3.2, circulating cooling water cooling water supply is not enough, the condenser will heat, the sound of air flow becomes larger, the degree of vacuum drops rapidly, and even steam will return to the suction pipe. For inter-tube cold condensers, water pressure should be guaranteed to 0.2MPa. The amount of water supply should be slightly larger than the actual amount, but too large will make the formation of water droplets condensation was inhaled, so that the pump can not work properly. General 1C water control at 67m3 / h, 2C water control at 12m3 / h. Cooling water temperature is too high, vacuum pump capacity will be reduced, or even can not afford to vacuum. Cooling water temperature generally does not exceed 32 ℃. The impact of cooling water on the vacuum pump capacity is also a factor that can not be ignored. If the water quality is poor, the hardness is high, it will cause the condenser fouling or clogging, seriously affecting the heat exchange performance, making the steam difficult to condense, thus affecting the degree of vacuum. So should ensure that the circulating cooling water is demineralized water.