Centrifugal Pump Flow Control Method
Method 1: The Export valve opening adjustment
In this method, the pump is connected in series with the outlet line regulating valve. The actual effect is like using a new pump system. The maximum output head of the pump is not changed, but the flow curve is attenuated.
Method 2: Bypass valve adjustment
In this method, the valve and the pump are connected in parallel. The actual effect is like the new pump system. The maximum output head of the pump changes and the flow curve characteristics also change. The flow curve is closer to the line shape.
Method 3: Adjust the impeller diameter
This method does not use any external components and the flow characteristic curve varies with diameter.
Method 4: Speed control
The impeller speed change directly changes the flow curve of the pump, and the characteristics of the curve do not change. When the speed decreases, the curve becomes flat, and the indenter and the maximum flow rate decrease.
The overall efficiency of the pump system, both the outlet valve adjustment and the bypass adjustment method, increases the line pressure loss and the pump system efficiency is greatly reduced. The impeller diameter adjustment has little effect on the efficiency of the whole pump system, and the speed control method basically does not affect the system efficiency, as long as the speed is not lower than 50% of the normal speed.
The main way of pump flow regulation
1, Change the pipeline characteristic curve
Change the centrifugal pump flow
2, Change the centrifugal pump characteristic curve
According to the law of proportionality and the law of cutting, changing the pump speed and changing the pump structure (such as the outer diameter of the cutting impeller) all can change the characteristic curve of the centrifugal pump to achieve the purpose of adjusting the flow rate (while changing the pressure head). But for pumps that already work, the method of changing the pump structure is not very convenient, because the pump structure has been changed, reducing the versatility of the pump, although it is economical and convenient to adjust the flow at some point, and is rarely used in production.
3, The pump series connection, parallel adjustment mode
When a single centrifugal pump cannot meet the delivery task, the parallel or series operation of the centrifugal pump can be used. Two same type pumps are used in the parallel connection. Although the head change is not large, the total delivery flow is increased. The total efficiency of the parallel pump is the same as that of a single pump; when the centrifugal pump is connected in series, the total head is increased. flow does not changes large, the total efficiency of the series pump is the same as that of a single pump.
Control effect
(1) The opening degree of the outlet valve is adjusted, the energy consumption is 94%, and the power consumption is large when the flow rate is low.
(2) Bypass adjustment, the bypass valve reduces the pump head to 55M, which can only be achieved by increasing the pump flow, resulting in a 10% increase in energy consumption.
(3) Adjusting the impeller diameter, reducing the impeller diameter, the output flow and pressure of the pump are reduced, and the energy consumption is reduced to 67%.
(4) Speed control, the speed is reduced, the flow rate and head of the pump are reduced, and the energy consumption is reduced to 65%.