Horizontal multi-stage centrifugal pump regulation which are the most commonly used two ways to introduce. 1, the valve throttling Change the centrifugal pump flow is the easiest way to adjust the pump outlet valve opening, while the horizontal multistage centrifugal pump speed remains unchanged (usually rated speed), its essence is to change the location of the pipeline characteristic curve ...
Horizontal multi-stage centrifugal pump regulation which are the most commonly used two ways to introduce.
1, the valve throttling
The simplest way to change the centrifugal pump flow is to adjust the pump outlet valve opening, while the horizontal multistage centrifugal pump speed remains the same (usually the rated speed), its essence is to change the position of the pipeline characteristic curve to change the pump Point situation. The intersection of the pump characteristic curve QH and the pipeline characteristic curve Q-Σh is the limit working point of the pump when the valve is fully open. When the valve is closed, the local resistance of the pipe increases, the pump operating point moves to the left and the corresponding flow decreases. When the valve is fully closed, it is equivalent to infinite resistance and zero flow. At this time, the pipe characteristic curve coincides with the ordinate. Thus, to close the valve to control the flow rate, the multistage centrifugal pump its own water supply capacity unchanged, lift characteristics unchanged, the tube resistance characteristics will change with the valve opening changes. This method is easy to operate, continuous flow, can be adjusted between a certain maximum flow and zero, and without additional investment, for a wide range of applications. However, the throttling regulation consumes the excess energy of the centrifugal pump (shaded part in the figure) to maintain a certain supply, and the efficiency of the centrifugal pump will also decrease, which is not economically reasonable.
2, Frequency Control
Operating conditions deviate from the high efficiency zone is the basic conditions for speed control. When the multi-stage centrifugal pump speed changes, the valve opening remains unchanged (usually the maximum opening), the same pipe system characteristics, and water supply capacity and head characteristics change. When the required flow rate is less than the rated flow rate, the lift of the frequency conversion speed regulation is smaller than the valve throttling, so the water supply power required by the frequency conversion speed regulation is also smaller than the throttling of the valve. Obviously, compared with the valve throttling, energy-saving effect of frequency control is very prominent, horizontal multistage centrifugal pumps work more efficiently. In addition, the use of frequency control, not only help reduce the possibility of centrifugal pump cavitation, but also by the speed / deceleration time to extend the pre-set start / stop process, the dynamic torque is greatly reduced , Thus largely eliminating the damaging water hammer effect, greatly extending the life of pumps and piping systems.
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