Compressor leak gas interlock

The magnitude of the primary leakage level directly reflects the quality of the primary seal. The back pressure at the primary vent in a dry gas seal system is generally controlled using a control valve, so as to maintain a certain pressure at the primary vent outlet, which in turn determines the operating pressure of the secondary seal. After the secondary dry gas seal is damaged, the primary vent gas will be discharged through the secondary seal, and the back pressure of the primary vent will not be maintained. Therefore, the quality of the secondary seal can be determined by changes in the primary vent pressure. Therefore, there is a interlock between pressure and flow in the primary seal gas leakage pipeline; if the primary leakage is detected at an elevated level, it clearly indicates a problem with the primary seal. If the pressure or flow related to primary leakage is significantly below normal levels, it is possible that the secondary seal has been damaged.

The primary seal vents to the flare, while the secondary seal vents to the atmosphere; monitoring the flow rate of the vent stream actually serves to monitor both the primary and secondary seals. If the flow rate through the flare is higher than normal, it indicates a leak in the primary seal; if the flow rate is lower than normal, there may be a leak in the secondary seal, with the sealing gas escaping into the atmosphere through that seal.