GE mark VI Gas turbine speedtronic control load reduction cause


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Dear i am working in combined cycle power plant and recently we have faced a problem that is,

we have 2 gas turbine of GE mark VI speedtronic control and 1 steam turbine of siemens. Few days ago a dust storm came to our site followed by heavy rain. After that our one gas turbine load reduced almost 2 MW.

load reduced turbine parameter are,

pressure drop before and after filters = 70.3 mmH20, compressor inlet temperature = 28 C, compressor discharge pressure = 13 barg, compressor discharge temperature = 408 C

Please tell me the load reduction root causes and comment on it and give me a reasonable solution to increase our reduced load
It is difficult to do RCA off site to determine why only one of the GT's was affected.

But the problem that caused the output drop sounds like clogged air house filters. The dust from the storm dirtied your air house filters/pre-filters then the rain turned it into mud on your filters and it dried like a mud cake so now you have restricted airflow.

you may need to inspect/change filters/pre-filters and do compressor wash to get back your 2 MW.
But if this could be the cause than why the other GT has not reduced the load as they has same geographical area and location.

please review the previous prameters and current parameters of before and after filter DP of turbine which has reduced load.

previous filter DP = 0.118053 PSI
current filter DP = 0.09102 PSI

The turbine which has not reduced the load it has following parameters of before and after filter DP.

Previous filter DP = 0.118053 PSI
current filter DP = 0.118053 PSI

Please suggest that what could be the major root cause by keeping in view the parameters which i have mentioned if you need further information than i ready to provide that.

waiting for kind response.

Chatchai Mairieng

How about the CPD before and after of 2 units? Is it possible to check the compressor condition? The lower of DP does not mean the good condition of filter. Its maybe break away yet!