In order to solve the problems of the sealing and overload of the submersible sewage pump, the auxiliary impeller hydrodynamic sealing technology and the overload free design technology of the pump are applied to the submersible sewage pump, which greatly improves the sealing reliability and bearing capacity of the pump, and prolongs the service life of the pump.
The application of the one, auxiliary impeller fluid dynamic seal technology
The so-called hydrodynamic impeller seal Deputy refers to the installation of an open impeller in the opposite direction near the back of the coaxial pump impeller hub. When the pump works, the auxiliary impeller rotates along with the main shaft of the pump. The liquid in the auxiliary impeller will rotate together. The rotating liquid will generate an outward centrifugal force. On the one hand, the centrifugal force will stop the liquid flowing to the mechanical seal and reduce the pressure at the mechanical seal. On the other hand, the solid particles in the medium are prevented from entering the friction pair in the mechanical seal, reducing the wear of the mechanical seal grinding block and prolonging its service life. Vice impeller play a role in addition to sealing, but also can reduce the axial force in the submersible sewage pump is mainly in the axial force acting on the impeller on the liquid pressure force and the rotating part of the gravity of the composition, the direction of the two force is the same, efforts are made by the two forces add a. It can be seen that in the case of the same performance parameters, the axial force of the submersible pump is larger than that of the ordinary horizontal pump, and the balance is harder than the vertical pump. So in the submersible pump, the reason that the bearing is easy to damage is also closely related to the axial force. If the auxiliary impeller is installed, the direction of the pressure difference acting on the auxiliary impeller is opposite to the above two forces, which can cancel part of the axial force and prolong the bearing life. But the use of the auxiliary impeller seal system also has one drawback. That is to consume a part of the energy on the auxiliary impeller, which is usually around 3%. However, as long as the design is reasonable, the partial loss can be reduced to a minimum. Starch cyclone
Two, the application of the non overload design technology of the pump
In general centrifugal pump, the power is always increased with increasing flow, that is to say, the power curve is an increase with the rising flow curve, the use of the pump will bring about a problem: when the pump is in operation at the operating point for design, in general, less than the motor rated power power pump the use of this pump is safe, but when the pump head decreases, the flow will increase (from the pump performance curve can be seen), power is also increased. When the flow of flow exceeds the design point and reaches a certain value, the input power of the pump may exceed the rated power of the motor and cause the motor to be overloaded and burned. When the motor is overloaded, it either protects the motion of the system to stop the pump from turning, or protects the failure of the system to cause the motor to burn down. The pump head below the design point lift usage, in practice is often encountered, a situation is when the pump selection, pump head selected too high, but the actual use is to lower the lift pump use; another situation is in use the pump operating point is not very good sure, in other words the flow of pump need to be adjusted; there is a need to change the location of pump use. These three kinds of cases may make the pump overload and affect the reliability of the use of the pump. It can be said that for pumps with no full lift characteristics (including submersible sewage pumps), the scope of their use will be greatly limited. Full lift characteristics (also known as the so-called non overload characteristics) refers to the power curve increase with the rising flow speed is very slow, it is more desirable when the flow rate increased to a certain value, the power will not rise again, it will decline, that is to say the power curve is a hump curve, if such if we just choose the motor rated power is slightly more than the power of hump point value, then flow to the entire range of maximum flow, whether you run on that one point, the pump power will not exceed the motor power and the pump overload, to have the performance of the pump, either selection or when in use, will be very convenient and reliable. In addition, the motor power does not need to be too large, and can save considerable equipment cost.
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