Pump Technology

The working principle of centrifugal pump with large flow and low head

Sanchang pump will share the working principle of centrifugal pump with large flow and low head. Please see the following for details:

 

(1) The impeller is driven by the pump shaft to rotate and work on the fluid between the blades. The fluid is driven by centrifugal force and thrown to the periphery from the center of the impeller. When the fluid reaches the impeller, the flow velocity is very high.

 

(2) The pump casing collects the liquid thrown out from the blades. The liquid flows in the casing along the expanding direction of the volute channel, which transforms the kinetic energy of the fluid into the static energy and reduces the energy loss. Therefore, the function of pump shell is not only to collect liquid, but also an energy conversion device.

 

(3) Principle of liquid suction: depending on the high-speed rotation of the impeller, the liquid in the center of the impeller is forced to be thrown away at a very high speed, thus forming a low pressure in the center of the impeller, so the liquid in the low-level groove is continuously sucked up. Gas binding phenomenon: if the centrifugal pump is filled with gas before startup, when the gas in the center of the impeller is thrown after startup, it cannot form enough vacuum at this place, so that the liquid in the tank cannot be absorbed.

 

This phenomenon is called air binding. In order to prevent the occurrence of air binding, the centrifugal pump should be filled with external liquid before starting. This operation is called pump filling. In order to prevent the liquid injected into the pump shell from flowing into the low-level tank due to gravity, a check valve (bottom valve) is installed at the inlet of the pump suction pipeline; if the position of the pump is lower than the liquid level in the tank, the pump does not need to be filled during startup.

 

(4) The guide wheel is installed around the impeller, so that the liquid energy conversion efficiency in the pump is high. The guide wheel is a fixed ring with blades around the impeller.

 

The bending direction of this blade is opposite to the bending direction of the impeller blade, and the bending angle is just suitable for the direction of liquid flowing out of the impeller, which guides the liquid to change the direction smoothly in the pump casing channel, so as to minimize the energy loss and improve the efficiency of converting dynamic pressure energy into static pressure energy.

 

(5) The balance hole on the rear cover plate eliminates axial thrust. The liquid pressure away from the impeller periphery is already high, and some of it will seep into the rear of the impeller rear cover plate, while the liquid inlet at the front of the impeller is low pressure, thus generating the axial thrust to push the impeller to the inlet side of the pump.

 

This is easy to cause impeller and pump casing contact wear, serious vibration will occur. The balance hole makes part of the high pressure liquid leak to the low pressure area, reducing the pressure difference between the front and back of the impeller. But this will also reduce the efficiency of the pump.

 

(6) The shaft seal device ensures the normal and efficient operation of the centrifugal pump. Centrifugal pump in the work is the rotation of the pump shaft and the shell does not move. If the ring gap between them is not sealed or the seal is not good, the outside air will penetrate into the low-pressure area in the center of the impeller, which will reduce the flow and efficiency of the pump. When serious, the flow is zero - Air binding. In general, mechanical seal or packing seal can be used to achieve the seal between shaft and shell.

Contact Us

Contact: Ms. Chrissie Gao

Phone: 0086-19918814904

Tel: 0086-731-83972723

Add: No.517, Xiangfu Rd(E), Yuhua District, Changsha City, Hunan Province, P.R. China. ZIP:410000.