Currently, there are three types of balancing structures for multistage centrifugal pumps: self-balancing structure, balance disk structure, and balance drum structure. This article briefly introduces these three balancing structures.
1.Self-balancing structure of self-balancing multistage centrifugal pumps:
The axial forces generated during operation cancel each other out and can basically achieve self-balancing, so that the alignment of the impeller and guide vane is always in a balanced state, which improves the operating efficiency of the pump as a whole. It is a multistage centrifugal pump with an innovative structure.
2.Horizontal multistage pumps with balance drum structure:
Balance drums are mostly used for balancing the axial force of centrifugal compressors, where the working fluid is gaseous. But this is not absolute; for example, in compressors and blowers, although the medium is gas, it is also called a balance disk. There is no axial clearance in the balance drum. The labyrinth seal/comb tooth seal and the radial concave-convex grooves of the balance drum form a radial clearance, which can play a better pressure reduction role. The high-pressure gas flows through the radial clearance of the balance drum into the balance chamber, and then enters the balance pipe connected to the inlet, so that the pressure in the chamber is always equal to or slightly higher than the inlet pressure, so as to achieve the purpose of balancing the axial force.
3.Horizontal multistage pumps with balance disk structure:
The balance disk has an axial clearance. The balance chamber is connected to the inlet with a pipeline. The diameter of the balance disk should be selected such that the pressure difference between the two sides is sufficient to balance the axial force. A large axial thrust reduces the clearance and lowers the back pressure, achieving automatic balancing. To prevent excessive balance flow, an orifice plate can be added to the balance pipeline. The disadvantage of the balance disk is that the change in the pressure of the balance chamber will cause a change in the pressure of the stuffing box. The balance disk structure has a small leakage, but the balance disk is easy to wear.
