At present, the main energy saving technologies for water pumps in China include the following energy saving technologies: cutting impeller, frequency conversion technology, ternary flow technology and special energy saving pump. Now let's analyze the characteristics of these energy saving technologies.

1. Cutting impeller energy saving

As we all know, in the construction of centrifugal pumps, the impeller is an important component that determines the water volume and the head. Its working principle is that the high-speed rotating impeller drives the liquid inside it to rotate, thus generating centrifugal force. As we learned in the physics class of junior high school, an important factor determining the centrifugal force is the rotation radius. From this, we can see that once the impeller of a centrifugal pump is cut, that is, the diameter of the impeller is reduced, the centrifugal force of the liquid inside the impeller will be reduced, and the consequences can only be caused by the reduction of the flow, head and other parameters of the pump, which may cause hidden dangers to safety production.

2. Frequency conversion energy-saving technology

The main working principle of frequency conversion is to realize the effect of energy conservation by changing the frequency of the pump drive motor and reducing the speed of the motor. Its main application scope is: ① The load of the motor changes periodically with the needs of production conditions. In this condition, when the production load decreases, the load of the motor also decreases. The use of frequency conversion technology can reduce the speed of the motor at this time, So as to achieve the effect of energy saving, but in a system with relatively stable operating conditions, the energy saving rate of frequency conversion technology will be significantly reduced. ② It is suitable for some circulating water pumps with large margin of design parameters, that is, the so-called "big horse-drawn trolley", which has a certain effect. Under this condition, the frequency of the pump motor is changed by frequency conversion, the pump speed is reduced, and the operating points of the pump Q and H values are adjusted, so that the actual flow value of the water pump is lower than the rated flow value of the pump, so as to achieve the purpose of energy conservation.

The centrifugal pump is designed based on the specific speed under the condition of hydraulic characteristics as the similarity criterion. The geometric dimensions of the hydraulic model of the flow channel of each pump must correspond to its design parameters Q (flow), H (head), and r/min (speed) to produce the final efficiency of the pump. Therefore, the hydraulic model and geometric dimensions of the pump impeller cannot be changed with the change of the speed, so the variable frequency speed regulation will reduce the rated speed of the pump, and then the output flow of the pump will be reduced, the pump head will be reduced, and the actual efficiency of the pump will be reduced, which is far lower than the original efficiency value of the pump.

When the margin of the performance parameters Q and H of the circulating water pump selected for the industrial circulating water system is not large, if the actual parameters Q and H of the pump are reduced by frequency conversion speed regulation, the pump flow may be reduced too much, the system cooling water is insufficient, and the water temperature of the cooling water system may rise too high.

3. Three-dimensional flow technology

Three-dimensional flow technology is to divide the three-dimensional space inside the impeller infinitely, and establish a complete and real mathematical model of the flow inside the impeller by analyzing the working points in the impeller flow channel.

Through this method, the analysis of impeller flow channel can be done most accurately, and the flow field and pressure distribution of the fluid can be reflected most closely to the reality. The flow characteristics of jet and wake (vortex) at the impeller outlet are reflected in the design calculation. Therefore, the designed impeller can also better meet the working conditions, and the efficiency is significantly improved. However, if the impeller of the ordinary water pump is simply replaced with a three-way flow impeller, its energy-saving effect may not be as expected, because the single three-way flow impeller cannot change the water resistance and water loss of all the flow passage parts in the whole water pump when the pump shell and other parts have been finalized.

4. Special energy-saving water pump

The special energy-saving water pump is specially tailored for various types of circulating water systems. It comprehensively utilizes various technologies, combines the siphon principle, ternary flow technology and technical patents * *, and controls the whole process of design, mold opening, casting and processing of the special energy-saving water pump to make its design reasonable and mold opening meet the design requirements, and then applies advanced casting technology to reduce casting errors, and finally through careful processing and polishing, Make the final product consistent with the design concept.

When the fluid circulates inside the special energy-saving pump, it can present a relatively regular flow state, reduce the loss of inlet impact and outlet wake flow separation, greatly avoid the occurrence of turbulence, reduce the impact and flow separation of fluid in the design of the single-channel hydraulic model of ordinary pump, and avoid the formation of water backflow between the blades, so that the flow of water between the impellers is closer to the design state, improve the pump flow, and reduce the useless work, It reduces energy consumption and improves pump efficiency. The water pump using this technology can significantly reduce the effective shaft power of the water pump without any change in the flow, and fully meet the full-load operating conditions of the industrial system, without raising the water temperature of the cooling water system, with high efficiency, without changing the operating parameters of the system, and without any impact on the normal production.