LKH multistage centrifugal pump adopts the high-efficiency and energy-saving hydraulic model recommended by the state, which has the advantages of high-efficiency and energy-saving, wide range of functions, safe and stable operation, low noise, long service life, convenient installation and repair, etc. After changing the pump material, sealing method and adding cooling system, it can transport hot water, oil, corrosive and abrasive media. Different multi-stage centrifugal pump manufacturers produce different types of multi-stage centrifugal pumps. The multi-stage centrifugal pump is a combination of more than two pumps with the same function. In terms of fluid channel structure, the medium pressure relief port of the stage is connected to the inlet of the second stage, and the medium pressure relief port of the second stage is connected to the inlet of the third stage. Such a series organization forms a multi-stage centrifugal pump. The meaning of multistage centrifugal pump is to increase the set pressure.

1. Valve savings

The simple way to change the flow of the centrifugal pump is to adjust the opening of the outlet valve of the pump, while the rotating speed of the multistage centrifugal pump remains unchanged (usually the extra rotating speed). Its essence is to change the position of the pipeline characteristic curve to change the operating point of the pump. The intersection point of pump characteristic curve Q-H and pipeline characteristic curve Q-∑ h is the extreme operating point of the pump when the valve is fully opened. When the valve is turned down, some resistance of the pipeline is added, the working point of the pump moves to the left, and the corresponding flow is reduced. When the valve is fully closed, the resistance is infinite and the flow is zero. At this moment, the pipeline characteristic curve coincides with the ordinate. It can be seen that when the flow is controlled by turning down the valve, the water supply of the multistage centrifugal pump itself will remain unchanged, the head characteristics will remain unchanged, and the pipe resistance characteristics will change with the change of the valve opening. This method is easy to operate, continuous flow, and can be adjusted between a large flow and zero at will, without additional investment. It is widely used. But saving conditioning is to consume the residual energy of the centrifugal pump to maintain a certain supply, and the power of the centrifugal pump will also decline, which is not reasonable economically. Alfa Laval

2. Variable frequency speed regulation

The basic condition of pump demand speed regulation is that the operating point violates the high efficiency zone. When the rotating speed of the multistage centrifugal pump is changed, the valve opening remains unchanged (generally large opening), the characteristics of the pipeline system remain unchanged, and the water supply ability and head characteristics change accordingly. When the required flow is less than the additional flow, the head of variable frequency speed regulation is less than that of the valve, so the water supply power required by variable frequency speed regulation is also less than that of the valve. Obviously, compared with valve saving, the energy-saving effect of variable frequency speed regulation is outstanding, and the working power of horizontal multistage centrifugal pump is higher. In addition, the use of variable frequency speed regulation is not only conducive to reducing the possibility of cavitation of centrifugal pump, but also can extend the startup/shutdown process through preset speed increase/decrease time, greatly reducing the dynamic torque, thus largely eliminating the destructive water hammer effect and greatly extending the life of the pump and pipeline system.