Horizontal single-stage double-suction split case pump is a large-flow water pump, so it is inevitable to adjust the flow of double-suction split pump, so when adjusting, we must pay attention to some problems and adjustment methods. Because improper adjustment methods will have a serious impact on the effect of adjustment and the performance of the pump. This article mainly analyzes the three effective adjustment methods of the horizontal double-suction pump flow.
Change the piping characteristic curve of horizontal single-stage double-suction split pump
The easiest way to change the piping characteristic curve to change the flow of the center-split pump is to use the opening of the center-split pump outlet valve to control. The essence is to change the position of the piping characteristic curve to change the working point of the center-split pump.
Change the characteristic curve of horizontal single-stage double-suction split pump
According to the law of proportionality and the law of cutting, changing the speed of the double-suction centrifugal pump, changing the structure of the double-suction centrifugal pump (such as cutting impeller outer diameter method, etc.) can change the characteristic curve of the double-suction centrifugal pump, so as to adjust the flow rate (at the same time) Change the purpose of the indenter). But for the already working double-suction centrifugal pump, it is not convenient to change the structure of the double-suction centrifugal pump, and because the structure of the double-suction centrifugal pump is changed, the versatility of the double-suction centrifugal pump is reduced, although it is adjusted at some point The flow is economical and convenient, and it is rarely used in production. Here only analyze the method of changing the speed of the centrifugal pump to adjust the flow. Analysis, when changing the speed of the double-suction centrifugal pump to adjust the flow rate from Q1 to Q2, the speed of the double-suction centrifugal pump (or motor speed) drops from n1 to n2, the pump characteristic curve QH and pipeline characteristic curve He at the speed of n2 =H0+G1Qe2 (the pipeline characteristic curve does not change) intersect at points A3Q2, H3, and point A3 is the new operating point after the flow rate is adjusted by speed regulation. This adjustment method is effective, fast, safe and reliable. It can prolong the service life of the double-suction centrifugal pump and save energy. In addition, lowering the speed can effectively reduce the NPSHr of the double-suction centrifugal pump and keep the pump away from the cavitation zone. , To reduce the possibility of cavitation in the double-suction centrifugal pump. The disadvantage is that changing the speed of the pump requires the use of frequency conversion technology to change the speed of the prime mover (usually a motor). The principle is complicated, the investment is large, and the flow adjustment range is small.
Series and parallel adjustment mode of horizontal single-stage double-suction split pump
When a single double-suction centrifugal pump cannot meet the delivery task, parallel or series operation of double-suction centrifugal pumps can be used. Using two double-suction centrifugal pumps of the same model in parallel, although the pressure head changes little, the total delivery flow is increased. The total efficiency of the parallel pumps is the same as that of a single pump; the total pressure of the double-suction centrifugal pumps in series The head increases, the flow rate does not change much, and the total efficiency of the series pump is the same as the efficiency of a single pump.
