In papermaking production, how to choose a suitable vacuum pump to match it seems more complex. The liquid ring vacuum pump is the most common vacuum equipment in papermaking vacuum system. By introducing its development history, working principle, structural characteristics and the application characteristics of liquid ring vacuum pump in paper mills, this paper summarizes its advantages, hoping to provide references for the relevant technical personnel in the paper industry in choosing vacuum equipment.
Next, because the manufacturer of EVP vacuum pump introduces the development history of vacuum pump.
1. Liquid Ring Vacuum Pump Development History
Among all kinds of vacuum pumps, the liquid ring vacuum pump is the most widely used one in the paper mill field, and it is also one of the most important types of vacuum pumps with the fastest development of functional structure. With the continuous improvement of technological performance of liquid-ring vacuum pump, industrial robots, microelectronics, computers, intelligent and image sensing technology are widely used in the production system of pump industry. In the future market, the research and manufacture of liquid-ring vacuum pump will develop in the direction of high speed, multi-function and intelligent control. Motivation and integration will become the development direction of rotary vane pump in the future.
2. Liquid Ring Vacuum Pump Working Principle
The principle of liquid ring vacuum pump is that the pump shell is equipped with appropriate water as working fluid. When the centrifugal impeller rotates clockwise in azimuth, the water is thrown around by the centrifugal impeller. Because of the centripetal force, the water produces a closed ring which is approximately equal in thickness to the shape of the pump chamber.
The upper part of the inner surface of the water ring is just tangent to the circle of the centrifugal impeller, and the lower part of the inner surface of the water ring is just touching the top of the leaf (in fact, the leaf has the necessary insertion depth of 1 in the water ring).
At this time, a crescent-shaped interior space is created between the wheel ring and water ring of centrifugal impeller, and this interior space is divided into several small cavities with the same number of leaves by centrifugal impeller. If the upper end of centrifugal impeller is 0 degree as the starting point, the capacity of the small chamber increases from small to small when the impeller rotates 180 degrees, and interacts with the breathing port on the end surface. At this time, the vapor is sucked in, and at the end of the breathing, the small chamber is blocked from the breathing port.
When the centrifugal impeller rotates again, the small chamber shrinks from large to small, so that the steam body is reduced; when the small chamber interacts with the outlet, the steam body is discharged out of the pump.
3.Liquid Ring Vacuum Pump Structural Characteristics
The pump is composed of pump body, front and rear end caps, impellers, shafts and other parts. The intake pipe and exhaust pipe are connected with the pump chamber through the suction and exhaust holes installed on the disc on the end cover. The impeller is fixed on the shaft with keys and installed eccentrically in the pump body. The total clearance between the two ends of the pump is adjusted by the cushion between the pump body and the disc. The clearance between the impeller and the front and rear discs is adjusted by the impeller driven by the sleeve. The clearance between the two ends is uniform. For pumps above SK-12, the shaft and impeller are interference fit, and the clearance is determined by the front-end positioning. The clearance between the impeller’s two ends and the front and rear discs determines the loss of gas and its limit pressure in the flow from the inlet to the exhaust in the pump chamber.
4. Liquid Ring Vacuum Pump Application Characteristics
Modern paper machines use vacuum to help paper dehydration, so the vacuum system is an important part of a paper machine. There are several vacuum elements on a paper machine that require different vacuum degrees and need to be connected to the vacuum system. If the liquid ring vacuum pump is used to set up the vacuum system, some close points of vacuum degree are often combined, and several liquid ring vacuum pumps are selected to set up the vacuum system according to different vacuum degree. The use of vacuum pumps is independent, and there will be no interference or chain reaction between different vacuum pumps. Under the existing technical conditions, the comprehensive performance of liquid ring vacuum pump is better than others, so the application of liquid ring vacuum pump in paper mills occupies a dominant position. There is no mistake in choosing liquid ring vacuum pump.