The flow rate of centrifugal pump can be regulated by various methods. Generally, the pump works most reasonably at rated point, but sometimes the pump runs in a small flow due to some reasons.
Operating at the operating point will cause some negative effects below.
What are the disadvantages of centrifugal pumps operating at low flow rate for a long time?
What are the disadvantages of centrifugal pumps operating at low flow rate for a long time?
(1) The efficiency decreases and the power consumption increases. Centrifugal pumps are generally designed so that the highest efficiency is near the rated I point. If the centrifugal pump operates at a low flow point, its operation efficiency will be improved.
Generally, the smaller the flow rate of the same pump, the smaller the efficiency, so it is very uneconomical to operate under the condition of small flow rate. Usually, it needs to be heavy.
New equipped with suitable high efficiency small pump.
(2) Vibration and noise increase, causing environmental pollution, damaging pump parts, affecting the service life of the pump. At the design operating point, because the direction of the liquid flow is the same as that of the blade, the flow loss is caused.
The impact loss and eddy loss are relatively small, close to zero. However, when the pump works in a small flow area, it deviates from the design point, resulting in the loss of discharge, impact and vortices of the flow passage parts of the pump.
Losses are further increased, and these losses are accompanied by a large number of hydraulic noise and mechanical vibration.
(3) The internal reflux and cohesion heat of the pump increase greatly, which makes the temperature of the liquid in the pump rise, causes the heat of the pump body, affects the mechanical properties of the pump parts, and also causes the cavitation of the pump.
It can worsen and further affect the suction condition of the pump.
(4) The radial force of the centrifugal pump increases, which deteriorates the force acting on the rotor of the pump. Because the pump deviates from the design operating point when it works in a small flow area, the liquid flow velocity in the swirl chamber decreases, but the root of the flow rate decreases.
According to the analysis of velocity triangle, the flow velocity of liquid in impeller increases instead, so that the liquid can not converge, forming impact, increasing pressure and generating radial force.
