Air injection vacuum pump of working principle
Purpose of air jet vacuum pump According to the performance of air jet vacuum pump, in a variety of applications of vacuum systems, can be used as the following pumps. Main pump: Used in a vacuum system to obtain the required vacuum.
Crude pumping: Starting at atmospheric pressure, reducing the pressure of the system to the level at which the other pumping system begins to operate. Forestage pump: a vacuum pump used to maintain the forestage pressure of another vacuum pump below the maximum allowable forestage pressure. The front pump can also be used as a crude pumping pump. Maintenance pump: when the pumping volume is very small, the main front stage pump cannot be effectively used.
A auxiliary front stage pump with a small capacity is needed in the vacuum system to maintain the normal operation of the main pump.
The internal components of the jet vacuum pump are mainly composed of Laval nozzle and diffuser. The structure of the single-stage steam jet pump is basically the same as that of other levels. Its working process can be divided into three stages: adiabatic expansion stage, mixing stage and compression stage.
1. In the adiabatic expansion stage, after the working steam passes through the zoom nozzle, the pressure can be converted into velocity energy and enters the diffuser at a very high speed. At the same time, the working steam pressure drops at the exit of the nozzle, forming a vacuum to suck in the pumped gas;
2. In the mixing stage, the pumped gas enters the diffuser. In the diffuser, the steam collides and mixes with the pumped gas for energy exchange.
3. In the compression stage, after passing through the throat of the diffuser, the mixture velocity decreases and the pressure rises further. At the outlet of the diffuser reaches atmospheric pressure or the inlet pressure of the rear stage injector, the pumped gas is discharged;
The jet vacuum pump can better withstand temperature changes, so the pump can withstand higher temperature than the same type of pump without affecting its service life. The pump is widely used in the electronic industry, such as tube, picture tube, X-ray tube, as well as the refining and purification of semiconductor monocrystalline silicon, high boiling point oil distillation and purification separation, fluorescent lamp, vacuum flask high vacuum exhaust instrument.