1. Change the pipeline characteristic curve:
Change the flow of
centrifugal pump is the most simple method is to use the pump outlet valve opening to control, its essence is to change the position of the pipeline characteristic curve to change the working point of the pump.
2. Change the centrifugal pump characteristic curve:
According to the laws and cutting the proportion of law and to change the pump speed, change pump structure (such as cutting impeller diameter method), the two methods can change the characteristic curve of
centrifugal pump, so as to achieve the flow adjustment (change in pressure head at the same time). But work has been for pump, change structure of the pump is not easy, and due to the change of the structure of the pump, reducing pump versatility, although it at some time adjusting economic flow of convenient, in the production are rarely used.
The method of changing the speed regulating flow of the centrifugal pump is analyzed here. When to change the pump speed control traffic declined from Q1 to Q2, the pump speed (or motor speed) from N1 decreased to N2 and speed for N2 pump characteristics of Q-H curve and the pipeline characteristic curve He=H0+G1Qe2 (Banlut curve does not change over to point A3 (Q2, H3), A3 to regulate traffic flow through the speed operating point. This adjustment method regulation effect is obvious, high-efficient and safe *, can prolong the service life of the pump, energy saving, in addition to a reduction in speed operation can effectively reduce the centrifugal pump NPSH NPSHr, away from the pump cavitation area, reduces the possibility of cavitation [2] centrifugal pump generation the. The disadvantage is to change the speed of the pump needs to have a frequency conversion technology to change the original motivation (usually motor) speed, the principle of complex, large investment, and a small flow regulation.
3. The pump string, and even the way to adjust:
When the
single centrifugal pump can not meet the transport task, the centrifugal pump can be used in parallel or in series operation. Two same types of
centrifugal pumps in parallel, although the pressure head changed little, but increase the total transport flow, the overall efficiency of the pump in parallel and
single pump efficiency is the same; centrifugal pumps in series increase the total pressure head, flow changed little, the overall efficiency of the tandem pump and single pump efficiency.
Although these methods from the perspective of energy analysis is more reasonable, but the operation is not convenient, in fact, very little. Therefore, the actual production or to regulate the opening of the valve to regulate the flow is more common.
