How to use submersible sewage pump in engineering?
Issuing time:2022-10-31 15:51
The so-called auxiliary impeller hydrodynamic seal refers to an open impeller installed in the opposite direction of the same axis near the back of the impeller rear cover plate of the pump. When the pump is working, the auxiliary impeller rotates with the main shaft of the pump, and the liquid in the auxiliary impeller also rotates. The rotating liquid will generate an outward centrifugal force, which on the one hand supports the liquid flowing to the mechanical seal, reducing the pressure at the mechanical seal. On the other hand, solid particles in the medium are prevented from entering the friction pair of the mechanical seal, which reduces the wear of the wear block of the mechanical seal and extends its service life.
In addition to sealing, the auxiliary impeller can also reduce the axial force. In the submersible sewage pump, the axial force is mainly composed of the differential pressure force of the liquid acting 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 the sum of the two forces. It can be seen that under the condition of identical performance parameters, the axial force of submersible sewage pump is greater than that of general horizontal pump, and the balance is more difficult than that of vertical pump. Therefore, in submersible sewage pump, the bearing is easy to be damaged because of the large axial force.
If the auxiliary impeller is installed, the direction of the differential pressure force exerted by the liquid on the auxiliary impeller is opposite to the resultant force of the above two forces, which can offset some of the axial force and also play a role in extending the life of the bearing. However, the use of the auxiliary impeller sealing system also has a disadvantage, that is, a part of the energy will be consumed on the auxiliary impeller, which is generally about 3%. However, as long as the design is reasonable, this part of the loss can be completely reduced to the minimum.