Pressure issues in the balance pipes of centrifugal compressors
Thread Content
As the title suggests, our unit’s centrifugal compressor is equipped with a balance pipe on which there is a pressure gauge; the reading shows a slight positive pressure, roughly equal to the pressure at the compressor’s inlet. I would like to ask whether the working principle of this balance pipe is the same as that of the balance pipes in multi-stage pumps, and why the pressure indicated by the gauge isn’t the pressure difference between the inlet and outlet Could someone explain it in detail?
This is what I found on the forum: Generally, compressors are designed with two types of balance pipes. One is the primary balance pipe, which connects behind the balance disk to the inlet of the unit or to a certain stage; its main purpose is to balance the axial forces. The secondary balance pipe is located at the toothed part at the end of the unit’s shaft, and there is usually an air hole in the middle of those teeth to connect the two ends; its main purpose is to balance the pressure in the sealing chamber.
Friend upstairs: Isn’t it a sealed chamber after the balance disc? Do you mean the comb teeth on the dry gas seal?
This works on the same principle as the balance tube in multi-stage pumps. The pressure gauge does not show the pressure difference at the inlet; one end of the balance tube is connected to the suction inlet, while the other end is connected to the balance chamber. Therefore, the pressure shown by the gauge is the pressure in the balance chamber, or the pressure at the inlet.
The principle of balance is basically similar; the balance tube leads to the back of the balance disc, so the pressure measured in the two chambers is identical, and it is not the pressure difference between the inlet and outlet!
The principle is the same: what is connected is the pressure at the inlet and that in the chamber after pressure reduction
The main function of the balance tube is to balance the axial force
It should be a single-axis multi-stage compressor, right? If so, the balance tube is connected to the balance disc on the high-pressure side, serving to balance the axial force.