Vacuum Pump Suction Valve Blockage Identified by Infrared Camera.

Operation department reported increasing condenser vacuum. Condenser vacuum should be maintained at -710 mmHg. In the last three days, the highest vacuum was only -691 mm Hg. This condition was causing decreased turbine and overall power plant efficiency.
Condenser vacuum on this power plant were maintained by one vacuum pump ( one vacuum pump as redundant). The analysis was focused on this equipment. Infrared camera was used to identified any abnormality on the piping that connect condenser with this equipment. And it was found that some portion of the suction piping was 8 oC cooler than the other section.

The coolest section was after suction valve. It was suspected that the suction valve was blocked or partially opened and causing restricted flow of gasses.Recommendation was made to inspect suction valve opening/condition.

Inspection by mechanic verify that suction valve was only partially opened. Infrared scanning after inspection show the temperature was distributed evenly on all section and condenser vacuum rise to 705 mm Hg.