1. Several kinds of vacuum pumps commonly used in chemical industry-the common vacuum pumps in chemical industry can be simply divided into variable-volume vacuum pumps and jet vacuum pumps. Variable-volume vacuum pumps are devices that use the periodic change of pump chamber volume to complete suction and exhaust. Reciprocating vacuum pumps, rotary vane vacuum pumps, slide valve vacuum pumps, water ring vacuum pumps and Roots vacuum pumps belong to variable-volume vacuum pumps. Type vacuum pump. Jet vacuum pump is a momentum transfer pump that uses the high-speed jet generated by the pressure drop of Venturi effect to transport gas to the outlet. Water jet vacuum pump, steam jet vacuum pump, steam-water series jet vacuum pump and steam-water combined jet vacuum pump belong to the same kind of jet vacuum pump. 2. Working Principle and Advantages and Disadvantages of Variable Volume Vacuum Pump
(1) Reciprocating vacuum pump, rotary vane vacuum pump, slide valve vacuum pump and Roots vacuum pump inhale, compress and discharge gas by reciprocating motion or rotation of piston. Their advantage is that the vacuum degree of the new pump is relatively high, but the piston is a running part, so the wear of the piston is inevitable. With the increase of maintenance times, the working vacuum degree will continue to decline until it can not meet the production requirements. This kind of pump has the disadvantage of high working noise, high fuel consumption and high failure rate. Generally, it needs to open a spare one, which invisibly increases the cost of equipment investment and operation. In addition, if this kind of pump is used to pump condensable gases such as suction steam, lubricating oil will be emulsified, so it can only be used to suck non-condensable (air) gases, nor can it suck medium with granular shape, which limits its scope of application.
(2) Water ring vacuum pump rotates by an eccentric rotor with multi-blades installed in the pump shell, throwing water into the pump shell to form a water ring concentric with the pump shell, and the water ring and the rotor blades form a volume periodic change, thus inhaling, compressing and discharging gas. It has the advantages of large suction capacity at low vacuum and direct suction of condensable gases such as water vapor. Its shortcomings are low vacuum, inability to suck granular media, high-speed rotation of the rotor is not easy to do anti-corrosion treatment, so it can not suck corrosive media. 3. Working Principle and Advantages and Disadvantages of Jet Vacuum Pump
Jet vacuum pump is a momentum transfer pump that uses the high-speed jet generated by the pressure drop of Venturi effect to transport gas to the outlet. It is divided into water jet vacuum pump, steam jet vacuum pump, steam-water series jet vacuum pump, steam-water combination jet vacuum pump. Jet vacuum pump is widely used in chemical operation because of its wide vacuum range, direct suction of condensable gases such as water vapor and granular media, simple structure, easy operation, small maintenance of non-operating components, energy saving and consumption reduction.
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