Currently vacuum technology is more and more widely used in such industries as vacuum, evaporation, crystallization, distillation, sublimation, drying, vacuum concentration, dehydration, chemical reaction absorption and vacuum conveying materials in the petroleum, chemical, pharmaceutical, After the application of vacuum technology in the process of processing, it can save energy, speed up the reaction, improve product quality and increase economic benefits. Gradually, the vacuum technology is a scientific edge. The vacuum industry in our country digested and absorbed the former Soviet Union and 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 process of industrial production how to apply a good vacuum pump, you need to make clear the following concepts: (1) The concept of "vacuum": "Vacuum" refers to the state of gas below a single atmospheric pressure in a given space, that is, the density of gas molecules in the space that is lower than the atmospheric pressure of that area. 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 reach when the amount of steam extracted is zero. Unit: Pa, kPa, MPa or mmHg (ultimate absolute pressure minus the local atmospheric pressure for the ultimate vacuum) (5) working pressure (vacuum): jet pump in the absolute amount of exhaust extraction pressure. Unit: Pa, kPa, MPa or mmHg (work pressure minus the local atmospheric pressure for the work of vacuum) (6) working steam pressure: working steam pressure of steam jet vacuum pump. 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 condenser circulating water temperature of the steam jet vacuum pump. Unit: ℃ (9) Cooling water circulation volume: circulating water flow rate per unit time through the water jet or steam jet pump condenser. Unit: kg / h 2, steam jet pump structure and working principle As the name implies, 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 production practice, we found that the quality of steam (steam pressure and steam dryness) is good or bad, which has great influence on the vacuuming ability and vacuum stability of the steam jet vacuum pump. 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 , <1.2MPa, and the steam pressure supplied by the boiler should be stable. Steam dryness has a greater impact on the performance of the vacuum pump. Water will cause vacuum fluctuations, too much water or even can not afford to vacuum, the general must be installed before the steam drum separator to achieve the required steam dryness, while the effective steam pipe insulation, the best working steam temperature 5 ℃ ~ 10 ℃. 3.2, circulating cooling water Cooling water supply is not enough, the condenser will heat, the sound of the air becomes larger, the vacuum drops rapidly, and even the 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. More Keyword Search: Vacuum Pumps