Measures To Improve The Self-priming Performance Of Sanitary Rotary Vane Pumps

Sanitary Rotary Lobe Pump has the characteristics of simple structure, good self-priming performance, strong sewage discharge capacity, high efficiency and energy saving, easy use and maintenance, etc. It is the first domestic product in the sewage pump series. Various technical performance indicators are leading in China and have reached the international advanced level, with broad application market and development prospects. It adopts axial reflux external mixing, and through the unique design of pump body and impeller flow channel, it can not only do not need to install bottom valve and water diversion like general self-priming clean water pump, but also can absorb and discharge liquid containing large solid particles and long fiber impurities. It can be widely used in municipal sewage projects, river pond breeding, light industry, papermaking, textile, food, chemical industry, electricity, fiber, slurry and mixed suspension and other chemical media. The most ideal impurity pump

The self-priming height of the sanitary rotary vane pump is related to the impeller front seal gap, the number of pump revolutions, and the liquid level of the separation chamber. The smaller the impeller front seal gap, the greater the self-priming height, which is generally taken as 0.3~0.5 mm; when the gap increases, in addition to the decrease in self-priming height, the pump head and efficiency are reduced. The self-priming height of the pump increases with the increase of the circumferential speed u2 of the impeller. However, when the maximum self-priming height is reached, the self-priming height no longer increases with the increase of the speed. At this time, it only shortens the self-priming time. When the speed decreases, the self-priming height decreases. Under the condition that other conditions remain unchanged, the self-priming height also increases with the increase of the water storage height (but it cannot exceed the optimal water storage height of the separation chamber). In order to better mix the air and water in the self-priming pump, the impeller blades must be fewer and the pitch of the blade grid is increased; and it is advisable to use a semi-open impeller (or an impeller with a wider impeller groove), which makes it easier for the return water to penetrate deeply into the impeller blade grid.

Measures to improve the self-priming performance of sanitary rotary vane pumps:
(1) Increase the maximum circumferential speed of the impeller outlet and the outlet width of the impeller blades. The maximum circumferential speed of the impeller outlet can be achieved by increasing the impeller speed directly. However, excessively increasing the maximum circumferential speed of the impeller outlet and the outlet width of the impeller blades will change the basic performance parameters of the pump such as flow rate and head. Therefore, the maximum circumferential speed of the impeller outlet and the width of the impeller blade outlet should be appropriately increased under the premise that the flow rate and head of the pump meet the use requirements.
(2) The relationship between water storage capacity and self-priming performance: When the water storage capacity increases, the self-priming height of the pump increases significantly, but when the water output is too large, the gas discharge process will be slowed down, that is, the self-priming time will increase. Therefore, when the self-priming height requirement is high but the self-priming time requirement is not too strict, the water storage capacity of the pump can be increased, that is, the volume of the liquid storage chamber can be increased, but when the self-priming time requirement is strict, the size of the liquid storage chamber should be reasonably determined.
(3) The relationship between the reflux hole area and the self-priming time and self-priming height: Within the critical reflux hole area, when the reflux hole area increases, the self-priming time decreases, and the self-priming height decreases accordingly. Therefore, when the self-priming time requirement is strict and the self-priming height requirement is not high, the area of ​​the reflux hole can be appropriately increased, otherwise, the area of ​​the reflux hole should be appropriately reduced.
(4) Setting up a gas-liquid separation acceleration device can accelerate the gas-liquid separation, that is, shorten the self-priming time. The simplest gas-liquid separation acceleration device is to add a baffle in the gas-liquid separation chamber. As shown in Figure 1. Adding a baffle in the gas-liquid separation chamber has almost no effect on the self-priming height. Therefore, as long as the structure allows, a baffle should be set in the gas-liquid separation chamber to accelerate the separation of gas and liquid and shorten the self-priming time.