Figure 1: Water pump impeller.
As we all know, the impeller is an important component in the composition of centrifugal pump that determines the water volume and head. Its working principle is that the high-speed rotating impeller drives the internal liquid to rotate, thus generating centrifugal force. An important factor that determines the size of 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, and the centrifugal force of the liquid inside the impeller will certainly be reduced. As a result, the flow, head and other parameters of the pump will decrease, which may cause hidden dangers to safety production.
The main working principle of frequency conversion is to change the frequency of the pump drive motor by frequency conversion and reduce the motor speed to achieve the effect of energy conservation.
Figure 2: Variable frequency motor water pump.
Its main application scopes include: the load of the motor changes periodically with the needs of the production conditions. Under such conditions, when the production load is reduced, the load of the motor is also lowered. The speed of the motor at this time can be reduced by using the frequency conversion technology, so as to achieve the effect of energy conservation. However, in the system with stable operating conditions, the energy conservation rate of the frequency conversion technology will be significantly reduced.
It is applicable to some water pumps with large surplus of design parameters in the circulating water system, that is, the so-called "big horse pulls a small cart". Under this condition, the frequency of the pump motor is changed by frequency conversion,
the pump speed is reduced, and the Q and H operating points of the pump are adjusted to make the actual flow value of the water pump lower than the rated flow value of the pump, so as to achieve the purpose of energy conservation.
Figure 3: Centrifugal pump.
Centrifugal pump is designed with the specific speed under the best hydraulic characteristics as the similarity criterion. The geometric dimension of the hydraulic model of each pump channel must correspond to its design parameters Q (flow), H (head) and r/min (speed) one by one to produce the final efficiency of the pump. Therefore, the hydraulic model and geometric dimension of the pump impeller cannot be changed correspondingly with the change of speed. Variable frequency speed regulation lowers the rated speed of the pump, and then the output flow of the pump decreases, the pump head decreases, and the actual efficiency of the pump decreases, which is far lower than the original efficiency value of the pump.
When the performance parameters of water circulating pump such as Q and H in industrial circulating water system have little surplus, if frequency conversion speed adjustment is adopted to reduce the actual parameters Q and H of the pump, it may cause excessive flow reduction of the pump, insufficient cooling water of the system, and increase the water temperature of the cooling water system.
The three-dimensional flow technology is to divide the three-dimensional space inside the impeller infinitely. Through the analysis of the working points in the impeller channel, a complete and real mathematical model of the flow in the impeller is established.
Figure 4: Impeller, cylindrical coordinates (R, Φ, Z) and flow velocity W.
Through this method, the analysis of the impeller passage can be done most accurately, and the flow field and pressure distribution of the fluid can be reflected most closely to the reality. The impeller outlet has the flow characteristics of jet-flow and wake (vortex), which can be reflected in the design and calculation. Therefore, the designed impeller can better meet the requirements of working conditions, and the efficiency is markedly improved.
However, if the impeller of an ordinary water pump is simply replaced with a three-dimensional flow impeller, the energy conservation effect may not reach the expectation. Because a single three-dimensional flow impeller cannot change the water resistance and water loss of all flow components inside the entire water pump when the pump case and other components have been finalized.
The energy-saving special water pump is specially tailored for various types of circulating water systems. It comprehensively utilizes various technologies, perfectly integrates the siphon principle, three-dimensional flow technology and technical patents, and controls the whole process of design, mold opening, casting and processing of the special energy conservation water pump, so that its design is reasonable and mold opening meets the design requirements, and then applies the advanced casting process to reduce the casting error. Finally, through careful processing and polishing, make the final product consistent with the design idea and reach the best state.
Figure 5: Swimming pool water circulation system.
When the fluid circulates inside the special energy conservation water pump, it can show a relatively regular flow state, reduce the loss of inlet impact and outlet wake flow, greatly avoid the occurrence of turbulence flow, reduce the impact and separation of flow of fluid in the design of the single channel hydraulic model of the ordinary pump, and avoid the backflow of water among the blades, so that the flow of water among the impellers is closer to the design state, improve the flow and reduce the useless work, The energy consumption is reduced and the efficiency of the water pump is enhanced.
The water pump applied 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 operation condition of the industrial system, without raising the water temperature of the cooling water system. It features high efficiency, does not change the operating parameters of the system, and has no impact on the normal production work.