Dry gas seal balance line pressure difference in centrifugal compressors
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The portion highlighted is the two ends of the balance tube; the left end is connected to the intake side of the machine, while the right end is connected to the outside of the exhaust side labyrinth. A pressure difference is created by the pressure from the balance tube and the pressure from the primary sealing gas. I don’t understand this pressure measurement point – why is it located inside the chamber rather than outside the labyrinth? With this setting, what pressure is being balanced? I would appreciate your guidance.
This diagram is missing some details; for example, the impeller inlet and the volute of a closed-type impeller are equipped with comb-toothed seals. Additionally, at one end of the rotor’s impeller, there is a device called a balance disk, which helps to balance the axial forces by utilizing its area under stress. Additionally, regarding the balance of axial forces, there are many methods for achieving balance on the rotor, which need to be carefully examined. Your diagram still lacks many details; it’s best to study the original blueprint*. For reference.
From your diagram, it seems that the goal is to ensure that the pressure of the sealed gas is higher than the suction pressure in order to prevent leaks. The balance tube is used to counteract the axial force of the impeller directed toward the inlet
Out of curiosity, I’m asking: other pipelines all have flow direction indicators, but this one doesn’t. Is it perhaps a marker indicating discharge?
This post was last edited by Front Row Viewer on 2020-8-2 at 10:01. This is likely the diagram for the dry gas seal of the compressor, showing the pressure sampling point for the secondary balance pipe within the pressure difference between the primary seal gas and the secondary balance pipe； The pressure in the secondary balance line is the compressor inlet pressure, while the pressure of the primary seal gas is the outlet pressure ； If pressure is not taken after sealing the labyrinth ； The pressure difference cannot be established ； If sealing gas cannot be injected, it will damage the dry gas seal. The compressor must maintain this pressure difference during operation ； If the pressure difference cannot be maintained during normal operation of the unit, it is basically because the labyrinth seal has failed.
The left side of the balance tube leads to the compressor inlet, while the right side leads to the back side of the balance drum. Gas flows from the compressor outlet side through the balance tube to the inlet side, creating a pressure difference on both sides of the balance drum, which generates a balancing force to counteract the axial force. The pressure in the balance tube is slightly higher than the inlet pressure and lower than the pressure of the primary seal gas.
This is a method that uses a balance drum to balance the axial thrust of the centrifuge; see the image analysis for details!
This is the diagram for the dry gas seal, showing the differential pressure between the balance pipe and the primary seal gas.