(1) Overview
The water ring-atmospheric jet vacuum pump set is a vacuum pump set composed of a water ring pump and an atmospheric jet pump. It can extract air and other non-corrosive, water-insoluble, and solid-free gases; it can also extract flammable, explosive, moisture-containing, and dust-containing gases. The temperature of the pumped gas generally does not exceed 40°C, and the highest vacuum obtained is 1000Pa.

The characteristic of the water ring-atmospheric jet vacuum pump unit is that it can increase the ultimate pressure and pumping speed of the water ring pump or liquid ring pump. Because the limit pressure of a single two-stage water ring pump is 2000Pa-- 4000Pa, the pumping speed is generally unstable when the pressure is higher than 4000Pa, and the pumping speed gradually tends to zero as the inlet pressure decreases. The water ring-atmospheric jet pump not only has a lower ultimate pressure, but also has a significantly increased pumping speed when the pressure is low.

Water ring-atmospheric jet vacuum pumps are widely used in vacuum concentration, vacuum impregnation, vacuum drying, molten steel degassing and other fields.

(2) Working principle
The working principle of the water ring-air pump is based on the working principles of the water ring pump and the air pump.

Start the water ring pump to cause the pre-vacuum required for the work of the atmospheric pump. There is a pressure difference between the inlet and outlet of the nozzle, and the air flows into the pump through the nozzle. When the pressure difference reaches more than half of the atmospheric pressure (that is, the ratio of the nozzle outlet pressure to the atmospheric pressure is equal to or less than 0.528), the combed gas is accelerated through the contraction section of the nozzle, and the airflow at the throat of the nozzle reaches the speed of sound, and then passes through the expansion of the nozzle. section, gain further acceleration, and finally shoot towards the diffuser at supersonic speed. At the same time of the rapid increase of kinetic energy, accompanied by the decrease of pressure, a higher vacuum in the mixing chamber is formed, which is lower than the pressure of the pumped container, so that the pumped gas is inhaled.

During the mixing process of the two airflows, due to the exchange of momentum, especially the shock wave generated by the contraction section of the diffuser, the shock wave loss caused the speed of the mixed airflow to slow down continuously; when entering the throat of the diffuser When it reaches the exhaust pressure of the atmospheric pump, that is, the suction vacuum of the water ring pump, the water ring pump The gas is carried away and exhausted to the atmosphere.