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We’re experiencing a recurring condenser vacuum deterioration issue in our steam turbine system with a two-stage steam ejector (primary & secondary with inter/after coolers).
This is the fourth occurrence of the same problem:
1. First two times: Vacuum improved by hit-and-trial — changing ejector sets (A/B) and running the hogger temporarily restored vacuum.
2. Third time: Vacuum restored after isolating and reintroducing the secondary ejector aftercooler trap.
3. Current incident: Again, trap isolation immediately improved vacuum, though vent flooding (steam/condensate at secondary vent) was observed for a short period.
Key observations:
Condenser vacuum drops gradually from around −84 to −71 kPa.
Turbine exhaust vacuum also rises correspondingly.
Both ejector sets receive normal motive steam (pressure and temperature stable).
Trap bypass has been open since commissioning without earlier issues.
When trap or bypass is open, vacuum worsens; when trap isolated, vacuum recovers.
Query points:
1. Why does trap isolation consistently restore vacuum if the bypass had always been open before without issue?
2. Could the trap or associated condensate line be causing intermittent flooding or steam leakage affecting ejector performance?
3. How can we confirm trap performance in operation under vacuum conditions (temperature difference, backpressure, etc.)?
4. Are there other possible ejector or inter-condenser causes linking this repeated pattern to condensate handling?
This is the fourth occurrence of the same problem:
1. First two times: Vacuum improved by hit-and-trial — changing ejector sets (A/B) and running the hogger temporarily restored vacuum.
2. Third time: Vacuum restored after isolating and reintroducing the secondary ejector aftercooler trap.
3. Current incident: Again, trap isolation immediately improved vacuum, though vent flooding (steam/condensate at secondary vent) was observed for a short period.
Key observations:
Condenser vacuum drops gradually from around −84 to −71 kPa.
Turbine exhaust vacuum also rises correspondingly.
Both ejector sets receive normal motive steam (pressure and temperature stable).
Trap bypass has been open since commissioning without earlier issues.
When trap or bypass is open, vacuum worsens; when trap isolated, vacuum recovers.
Query points:
1. Why does trap isolation consistently restore vacuum if the bypass had always been open before without issue?
2. Could the trap or associated condensate line be causing intermittent flooding or steam leakage affecting ejector performance?
3. How can we confirm trap performance in operation under vacuum conditions (temperature difference, backpressure, etc.)?
4. Are there other possible ejector or inter-condenser causes linking this repeated pattern to condensate handling?
