Instruction of the principle of water ring vacuum pumps
Water ring vacuum pump (referred to as water ring pump for short) is a kind of rough vacuum pump, which can obtain 4~8kPa ultimate pressure for the single-stage pump, and 2~4kPa for 4 ~ 8kPa for the two-stage pump. Water ring pump can be widely used in many technical processes in the petroleum, chemical, machinery, mining, light industry, paper-making, power, metallurgy, medicine, food and other industries and municipal and agricultural sectors, such as vacuum filtration, vacuum feeding, vacuum degassing, vacuum evaporation, vacuum concentration, vacuum resurgence, etc.
As the gas compression process of the water ring pump is under isothermal condition, the flammable and explosive gases can be exhausted, as well as gases containing dust and water; therefore the application of the water ring pump is growing.
The figure is the functional diagram of water ring pumps. The water ring pump consists of the impeller, pump body, suction and exhaust tray, water ring formed by water at the inner wall of pump body, air entry, air outlet, auxiliary exhaust valve, and other components. The impeller is eccentricly installed in the pump body. When the impeller rotating by the direction showed in the figure, the water entering the body of water ring pump impeller pump body is thrown around by the impeller, and as a result of centrifugal force, the water forms a closed water ring constant thickness which is similar with the shape of the pump chamber. The internal surface of the upper part of water ring pump is exactly tangental to impeller wheel hub, and the internal surface of the lower part exactly contact the top of vanes (in fact, vanes are inserted into the water ring for a certain depth). At this time, a crescent-shape space is formed between the impeller wheel hub and the water ring, which is divided into several small chambers with same number of vanes by the impeller. If regard the of upper part of the impeller as the starting point, when the impeller rotating for 0~180, the capacity of the small chamber gradually increases, and pressure continuously gets down. As the chambers are connected with the air entry of the suction and exhaust tray, when the pressure in the small chamber space is lower than that in the container in which the gas is pumped, according to the principle of gas pressure balance, the pumped gas is continuously drawn into the small chamber, that is, the pump is in the process of suction. When the suction is completed, the small chamber is isolated from the air entry. The capacity of the small chamber is gradually reduced, the pressure continuously increases, that is the pump is in the process of compression. With the pressure of the compressed gas reaches the exhaust pressure in advance, it will be exhausted from the auxiliary exhaust valve. The capacity of the small chamber which connected with the air outlet is further reduced, and its pressure further increases. When the gas pressure is higher than the exhaust pressure, the compressed gas will be exhausted from the air outlet. In the continuous running of the pump, it continuously repeats the process of suction, compression, and exhaust, so as to achieve continuous pumping. In the water ring pump, the auxiliary exhaust valve is a special structure, and generally, it is a rubber ball valve. It is for eliminating the over compression and insufficient compression in the operation of the pump. The two phenomena will cause excessive power consumption. As the water ring pump does not have a direct exhaust valve, and exhaust pressure is always fixed, the compression ratio of the water ring pump is determined by the stop position of the air inlet and the initial position of the air outlet, however, the two positions are fixed; therefore it can not meet the needs of the variable suction pressure. To solve this problem, in general, a rubber ball valve will be equipped under the air outlet, so that when the pressure in the pump chamber reaches exhaust pressure before the time, the ball valve automatically opens and the gas is exhaust gas to eliminate the phenomenon of over compression. In general, for the design of the water ring pump, the compression ratio is always determined based on the minimum suction pressure to determine the initial position of the air outlet. As a result, insufficient compression is eliminated.
Range of use
They are mainly applied to paper-making, chemical industry, petrochemical industry, pharmacy, food, metallurgy, building materials, electric, coal washing, cradling, fertilizer and other industries for pumping air or other gases which are not soluble in water, free of solid particles and non-corrosive. As they adopt the single-stage and single-acting structures, pumps of this series possess compact structures, and are easy to maintain, reliable to use, as well as energy-efferent.