The horizontal multistage centrifugal pump has the characteristics of high efficiency, wide performance range, safe and stable operation, low noise, long service life and convenient installation and maintenance. For transporting clean water or other liquids with physicochemical properties similar to water. It is mainly used for water supply and drainage, fire water, factories, mine water supply and drainage, long-distance water transportation, water in production process cycle, HVAC cycle, domestic water and other uses.
What are the adjustment methods for horizontal multistage centrifugal pumps, we introduce them in the two most common ways.
1. The simplest way to change the flow rate of the centrifugal pump is to adjust the opening of the pump outlet valve, while the horizontal multistage centrifugal pump keeps the same speed (generally rated speed), which is essentially changing the position of the pipeline characteristic curve. To change the operating point of the pump. The intersection of the pump characteristic curve Q-H and the pipeline characteristic curve Q-∑h is the limit operating 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 rate decreases. When the valve is fully closed, it is equivalent to an infinite resistance and the flow rate is zero. At this time, the characteristic curve of the pipeline coincides with the ordinate. It can be seen that when the flow rate is controlled by closing the small valve, the water supply capacity of the multi-stage centrifugal pump itself is unchanged, the head characteristic is unchanged, and the pipe resistance characteristic will change with the change of the valve opening degree. This method is easy to operate, continuous flow, and can be adjusted freely between a certain maximum flow rate and zero, and no additional investment is required. However, the throttling adjustment is to maintain a certain amount of supply by consuming the excess energy of the centrifugal pump, and the efficiency of the centrifugal pump will also decrease, which is not economically reasonable.
2. Frequency control The deviation of the operating point from the high efficiency zone is the basic condition for the pump to be speed regulated. When the speed of the multistage centrifugal pump changes, the valve opening remains the same (usually the maximum opening), the piping system characteristics remain unchanged, and the water supply capacity and head characteristics change. When the required flow rate is less than the rated flow rate, the head of the variable frequency speed regulation is smaller than the throttle of the valve, so the water supply power required for the frequency conversion speed regulation is also smaller than the throttle of the valve. Obviously, compared with the valve throttling, the energy-saving effect of the frequency conversion speed regulation is very prominent, and the horizontal multi-stage centrifugal pump has higher working efficiency. In addition, the use of variable frequency speed regulation not only helps to reduce the possibility of cavitation of the centrifugal pump, but also can extend the start-up/stop process by presetting the up/down time, so that the dynamic torque is greatly reduced. , thus largely eliminating the highly destructive water hammer effect, greatly extending the life of the pump and piping system
