(1)Change the opening of the valve
Change the valve switch on the centrifugal pump outlet line, and its essence is to change the pipeline characteristic curve. As shown below, when the valve off hours, increased local resistance line, pipeline characteristic curve steepens, the operating point move by the M M1, flow from the QM reduced to QM1. When the valve is opened wide, the line resistance is reduced, the pipeline characteristic curve becomes flatter, the operating point moves to M2, the flow increased to QM2.
Valves regulate the flow quickly and easily, and traffic can be continuously changed, suitable for continuous production of chemical characteristics. It is widely used. The disadvantage is that the valve off hours, increase the resistance loss, increased energy consumption, very economical.
(2) Change the speed of the pump
Change pump speed substantially change the pump characteristic curve. The original pump speed n, operating point M, as shown below, if the pump speed increased to n1, the pump characteristic curve H – Q move up, move the operating point by the M M1, increased flow from the QM to QM1. If the pump speed falls n2, the operating point moves to M2, flow down to QM2.
This adjustment method requires expensive transmission gear or the prime mover, and it is difficult to achieve continuous adjustment of flow, so rarely used in chemical production.
So it is important to use centrifugal pump correctly.
