pump flow adjustment methods

pump flow adjustment commonly used the following methods:

(1) outlet valve adjustment, is the most commonly used, the most popular use. In the pump discharge pipe installed on the control valve, by changing the valve opening degree to achieve pump flow regulation, simple and reliable method, but the power loss is large, the economy is not good, small flow or small flow regulation is not good.

(2) variable speed regulation, by changing the pump impeller speed to adjust the pump flow, this method is very small additional power loss is the most economical method. But need to increase the variable speed mechanism and variable speed motor, the initial input cost is higher. Constant pressure frequency conversion water supply system and the central air conditioning cooling water (chilled water) circulation system is the frequency conversion velocity modulation in the water pump adjustment application two typical examples. The method of changing the speed is most suitable for turbines, internal combustion engines and DC motor-driven pumps. Variable speed control can also be used to change the motor speed, sometimes with a hydraulic coupler.

(3) bypass regulation, the use of bypass shunt regulator pump flow, can solve the problem of continuous operation of the pump in the small flow, but caused the shunt flow is not fully utilized additional losses increase, while process piping also increases.

(4) cutting the outer diameter of the impeller, by cutting the impeller diameter method to adjust the pump flow, power loss is small, but the impeller can not be restored after cutting only small flow direction to adjust the pump flow. And the cutting volume of the impeller is limited, the flow adjustment range is limited. Suitable for long-term work in a small flow and traffic change is not the occasion.

(5) replace the impeller pump, the replacement of the impeller diameter of different diameter or export regulation pump flow, power loss is small, but need to prepare a variety of diameter impeller, and adjust the flow range is limited.

(6) blocking part of the impeller flow channel, by blocking the impeller flow (even) to reduce the flow of the pump, the equivalent of export valve throttling adjustment, but the initiative to adjust the additional energy loss reduction than throttling regulating energy saving.

(7) adjust the exit angle of the blade, by changing the impeller blade exit angle to achieve the adjustment of pump flow, this method is used for axial flow pump.

(8) cavitation adjustment, by changing the pump inlet pressure (water level, suction valve) method, the pump cavitation, change the pump characteristic curve, thus changing the pump flow method. Practice has proved that if the use of appropriate cavitation adjustment, then the pump flow components of the damage is not serious; the other hand, it can automatically adjust the flow and reduce the pump power consumption. Cavitation regulation is generally more in small and medium-sized thermal power plant condensate pump on the use.

(9) to increase or decrease the number of pump units, by increasing, reducing the number of pump operation combined with the appropriate combination to achieve pump flow regulation.