liquid ring vacuum pump basic types and characteristics
Liquid ring vacuum pump can be divided into the following types according to different structures:
(1) Single stage single acting liquid ring vacuum pump: single stage means that there is only one impeller, and single acting means that every revolution of impeller, suction and exhaust are carried out once respectively. The limiting vacuum of the pump is high, but the pumping speed and efficiency are low.
(2) Single stage double acting liquid ring vacuum pump: single stage refers to only one impeller, and double acting refers to two times of suction and exhaust for each rotation of impeller. Under the same pumping speed, double acting water ring pump greatly reduces the size and weight compared with single acting water ring pump. Because the working chamber is symmetrically distributed on both sides of the pump hub, the load acting on the rotor is improved. This kind of pump has higher pumping speed and efficiency, but lower limit vacuum.
(3) Two stage liquid ring vacuum pump: most of the two stage liquid ring vacuum pumps are single acting pumps in series. In fact, the impeller of two single-stage and single acting water ring pumps is connected by a mandrel. Its main feature is that it still has large pumping speed and stable working condition under high vacuum.
(4) Atmospheric liquid ring vacuum pump: the atmospheric liquid ring vacuum pump is actually a series liquid ring vacuum pump unit of atmospheric ejector. The air pump in series in front of the liquid ring vacuum pump is to improve the limit vacuum and expand the scope of use of the vacuum pump.
Compared with other mechanical vacuum pumps, liquid ring vacuum pump has the following advantages:
(1) The structure is simple, the manufacturing accuracy is not high, and it is easy to process. It is easy to operate and maintain.
(2) The structure is compact, and a larger exhaust volume can be obtained with a smaller structure size.
(3) There is no metal friction surface in the vacuum pump cavity, so it is unnecessary to lubricate the vacuum pump. The seal between the rotating part and the fixed part can be directly completed by the water seal.
(4) The temperature change of the compressed gas in the vacuum pump cavity is very small, which can be considered as isothermal compression, so the flammable and explosive gas can be removed.
(5) As there is no exhaust valve and friction surface, it is possible to pump out dusty gas, condensable gas and gas water mixture.
liquid ring vacuum pump disadvantages:
(1) The efficiency is low, generally around 30%, and the better can reach 50%.
(2) Low vacuum. This is not only because of the limitation of structure, but also because of the limitation of saturated vapor pressure of working fluid.
Generally speaking, liquid ring vacuum pump is widely used because of its advantages of isothermal compression and water as sealing liquid, which can pump out flammable, explosive and corrosive gases, as well as gases containing dust and water.
liquid ring vacuum pump application
Application in electric power industry: condenser vacuum pumping, vacuum water absorption, flue gas desulfurization, fly ash transmission, turbine sealing pipe exhaust, vacuum exhaust, exhaust geothermal gas.
Application in petrochemical industry: gas recovery, gas recovery, gas pressure rise, enhanced oil recovery, gas collection, crude oil stabilization, vacuum distillation of crude oil, exhaust gas compression, steam recovery / gas pressure rise, filtration / paraffin removal, tail gas recovery, polyester production, PVC production, packaging, recycle gas compression, PSA, production, acetylene and hydrogen, etc Explosion gas compression, tower top vacuum system in crude oil vacuum distillation, vacuum crystallization and drying, vacuum filtration, vacuum transportation of various materials.
Applications in the manufacturing industry: drying (pallet, rotary, flip, cone and freeze dryer), reproduction / reactor drying, distillation, degassing, crystallization / vaporization, filling and / or material transfer.
Application in pulp and paper production: black liquor evaporation, coarse pulp washing machine, lime mud and filter, sediment filter, vacuum dehydrator, raw material and white water degassing system, mixing box compressor, suction tank, couch roll, suction roll and transfer roll, vacuum press, wool cloth suction tank, blow box.
Application in plastic industry: extruder degassing, setting table (profile), EPS foaming, drying, pneumatic conveying device, vinyl chloride gas extraction and compression.
Application in instruments: steam sterilization, respiratory device, air cushion, protective clothing, dental instrument, central vacuum system.
Application in environmental protection industry: wastewater treatment, biogas compression, vacuum water addition, wastewater purification / activated sludge tank oxidation, fishpond ventilation, waste gas recovery (biogas), biogas recovery (biogas), waste treatment.
Application in food and beverage industry: Salmon cleaner, mineral water degassing, salad oil and fat deodorization, tea and condiment sterilization, sausage and ham production, tobacco products humidification, vacuum evaporator.
Application in the packaging industry: inflate the packaging bag, fill the goods, open the bag by air extraction, transport the packaging materials and products, attach labels and package the goods with glue, lift the cardboard box by vacuum manipulator and assemble it, vacuum packaging and air exchange packaging (map), PET container production, drying of plastic particles, transportation and extrusion of plastic particles Machine degassing, injection molding, film removal and treatment of injection parts, drying of injection parts, blow molding of bottle body, plasma treatment, to set up isolation layer, pneumatic conveying of bottle body, filling and filling, labeling, packaging and molding, recycling.
Application in wood processing industry: keeping and lifting, wood drying, wood preservation, log impregnation.
Application in marine industry: condenser exhaust, central vacuum pumping, marine low-pressure air compressor, turbine seal pipe exhaust.
Application in facility treatment: drying floor, water pipeline anti-corrosion protection, central vacuum cleaning system.
Application in metallurgical industry: steel degassing.
Application in sugar industry: preparation of CO2, filtration of pollutants, application in evaporator and vacuum suction cup.
What are the selection points of liquid ring vacuum pump
1、 liquid ring vacuum pump Determination of the type of liquid ring vacuum pump
The type of liquid ring vacuum pump is mainly determined by the medium pumped, air volume required for operation, vacuum degree or exhaust pressure.
There are two points to pay attention to after the liquid ring vacuum pump works normally:
1. As far as possible, the vacuum degree of the selected vacuum pump is required to operate in the high efficiency range, that is, in the critical vacuum degree or the critical exhaust pressure area, so as to ensure that the vacuum pump can work normally according to the required conditions and requirements. Operation near the maximum vacuum degree or the maximum exhaust pressure range of the vacuum pump shall be avoided. In this area, not only the efficiency is very low, but also the work is very unstable, which is easy to make the vacuum pump produce vibration and noise. For vacuum pumps with high vacuum degree, cavitation often occurs when they operate in this area. The obvious phenomenon is noise and vibration in the vacuum pump. Excessive cavitation will cause damage to pump body, impeller and other parts, so that the vacuum pump can not work normally.
It can be seen that when the vacuum degree or gas pressure required by the vacuum pump is not high, it can be selected preferentially in the single-stage pump. If the requirements for vacuum degree or exhaust pressure are high, the single-stage pump is often unable to meet the requirements, or the pump is still required to have a large amount of gas under the condition of high vacuum degree, that is, the performance curve is required to be relatively flat under the condition of high vacuum degree, so the two-stage pump can be selected. If the vacuum degree is required to be above – 710mmhg, roots water ring vacuum unit can be selected as the vacuum pumping device.
2. Select the vacuum pump correctly according to the air extraction required by the system
If the type of vacuum pump or vacuum unit is selected, the correct model shall be selected according to the air extraction required by the system.