1. Several vacuum pumps frequently used in the chemical industry – vacuum pumps commonly used in the chemical industry can be simply divided into variable volume vacuum pumps and jet vacuum pumps. Variable volume vacuum pumps use the periodic variation of the pump chamber volume to complete the suction and exhaust. The device, reciprocating vacuum pump, rotary vane vacuum pump, slide valve vacuum pump, water ring vacuum pump, Roots vacuum pump are variable volume vacuum pumps. The jet vacuum pump is a momentum transfer pump that uses a high-speed jet generated by the pressure drop of the Venturi effect to deliver gas to the outlet. The water jet vacuum pump, the steam jet vacuum pump, the soda water series jet vacuum pump, and the soda-water combined jet vacuum pump belong to the jet vacuum pump.
2. Working principle and advantages and disadvantages of variable displacement vacuum pump
(1) Reciprocating vacuum pump, rotary vane vacuum pump, slide valve vacuum pump, Roots vacuum pump rely on the reciprocating motion or rotation of the piston to suck, compress and discharge the gas. Their advantage is that the pump used in the new one is relatively high in vacuum, but the piston is the running part, so the wear of the piston can not be avoided. As the number of inspections increases, the working vacuum will continue to decrease until the production requirements are not met. Such pumps have high noise, large fuel consumption and high failure rate, which is also a fatal shortcoming. Generally, one standby unit is required, which inevitably increases equipment investment and operating costs. In addition, if such a pump is used to pump a condensable gas such as water vapor, the lubricating oil will be emulsified, so it can only be applied to the suction of non-condensable (air) gas, and it is also impossible to suck the medium with granularity. It also limits its scope of application.
(2) The water ring vacuum pump rotates by the eccentric rotor with multiple blades installed in the pump casing, throwing water to the pump casing to form a water ring concentric with the pump casing, and the water ring and the rotor blade form a volume cycle change and thus The gas is drawn in, compressed and discharged. It has the advantage of high pumping capacity at low vacuum and direct suction of condensable gases such as water vapor. Its disadvantage is that the degree of vacuum is low; the medium with granularity cannot be sucked; the rotor is not easy to be treated with anti-corrosion at high speed, so it is not possible to pump corrosive media.
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