Weather the expeller seal have any influence to capacity or not?
The expeller not only plays a sealing role, but also can reduce the axial force. In the slurry pump, the axial force is mainly composed of the differential pressure force acted by the liquid on the impeller and the gravity of the whole rotating part. The action direction of these two forces is the same, and the resultant force is formed by adding the two forces. It can be seen that under the same performance parameters, the axial force of mud pump is larger than that of horizontal pump, and the balance difficulty is more difficult than that of vertical pump. Therefore, in the submersible sewage pump, the bearing is easy to damage, the reason is also has a great relationship with the axial force. If the expeller is installed, the direction of the differential pressure force acting on the expeller is opposite to that of the resultant force of the above two forces. Offset part of the axial force, it also plays a role in extending the bearing life. However, the use of expeller seal also has a disadvantage, that is to consume part of the energy on the expeller, generally about 3%, but as long as the design is reasonable, this part of the loss can be reduced to the minimum.
In the general slurry pump, the power always increases with the increase of flow, that is to say, the power curve is a curve rising with the increase of flow, which will bring a problem to the use of the pump. When the pump is running at the design operating point, generally speaking, the power of the pump is less than the rated power of the motor. The use of this pump is safe, but when the pump head is reduced, the flow rate will be increased. It will increase (as can be seen from the pump performance curve), and the power will also increase. When the flow exceeds the designed operating point flow and reaches a certain value, the input power of the pump may exceed the rated power of the motor, resulting in overload and burning of the motor. When the motor is overloaded, either the protection system acts to stop the pump, or the protection system fails to make the motor burn down. Pump head is lower than the design working point head, which is often encountered in practice. In general, when selecting the pump, the head of the slurry pump is selected too high, while in actual use, the pump is used to reduce the head; another case is that the operating point of the pump is not well determined, in other words, the flow of the pump needs to be adjusted frequently; there is another case The pump needs to be changed frequently. These three cases may overload the pump and affect the reliability of the pump.
