The double-suction centrifugal pump is a large-flow water pump, so it is inevitable to adjust the flow rate of the double-suction centrifugal pump. When adjusting, we should pay attention to some problems and adjustment methods. Because improper adjustment methods have a serious impact on the adjusted effect and the performance of the pump. This paper mainly analyzes the three effective adjustment methods of the double suction centrifugal pump flow. Changing the pipe characteristic curve The easiest way to change the flow rate of the pump in the middle is to use the opening degree of the outlet valve of the middle open pump to control. The essence is to change the position of the characteristic curve of the pipe to change the working point of the pump.
Change the split case pump characteristic curve
According to the law of proportionality and the law of cutting, changing the speed of the double-suction centrifugal pump and changing the structure of the double-suction centrifugal pump (such as the outer diameter of the cutting impeller) can change the characteristic curve of the double-suction centrifugal pump to achieve the regulation flow (at the same time) Change the purpose of the indenter). However, for a double suction centrifugal pump that has already been operated, it is not convenient to change the structure of the double suction centrifugal pump, and the versatility of the double suction centrifugal pump is reduced due to the change of the structure of the double suction centrifugal pump, although it is adjusted at some time. The flow rate is economical and is rarely used in production. Here, only the method of changing the rotational speed of the centrifugal pump to adjust the flow rate is analyzed.
Analysis, when changing the speed of the double-suction centrifugal pump to reduce the flow rate from Q1 to Q2, the speed of the double-suction centrifugal pump (or motor speed) drops from n1 to n2, and the characteristic curve QH and the pipeline characteristic curve of the pump at the speed of n2 =H0+G1Qe2 (the pipe curve does not change) is at point A3Q2, H3, point A3 is the new working point after adjusting the flow rate through the speed regulation. The adjustment method is obvious, fast, safe and reliable, can extend the service life of the double-suction centrifugal pump, save energy, and reduce the speed operation, and can effectively reduce the NPSHr of the double-suction centrifugal pump, so that the pump is away from the cavitation area. Reduce the possibility of cavitation in double suction centrifugal pumps. The disadvantage is that changing the speed of the pump requires changing the speed of the prime mover (usually the motor) through frequency conversion technology, the principle is complicated, the investment is large, and the flow adjustment range is small. Series and parallel adjustment of double suction centrifugal pump When a single double suction centrifugal pump can not meet the transportation task, parallel or series operation of double suction centrifugal pump can be used.
Two parallel suction pumps of the same type are used in parallel, although the head change is not large, but the total delivery flow is increased. The total efficiency of the parallel pump is the same as that of a single pump; the total pressure of the double suction centrifugal pump in series The head is enlarged and the flow rate is not changed much. The total efficiency of the series pump is the same as that of a single pump.
