Dear Gents,

we are operating two GE 7FA gas turbines in co-generation mode,

one typical problem we are facing is that our unit#01 Gas turbine degrading faster (within 20 days), and we are recovering the same output after offline water wash, usually we are recovering 7 to 8 MW after offline water wash,

the recovering of the output indicates of heavy compressor fouling

For trouble shooting we checked the following thing

1. air inlet filter house filters integrity checked and all filters were found intact

2. Checked the filter pulsing sequence and found normal

3. checked the inletplenum rubber joints for any bypassing and found intact

4. checked the IGV angle and found OK

5. We are also having wheel space temperature high alarm= is there any correlation between high alarm and denigration?

6. upcoming shutdwon we are planning to check the offline/online water wash nozzles checks (spray test) to verify the integrity of the nozzles

7. Also we are planning to hand clan the IGV

Are there any ideas for trouble shoot? have u faced the similar problem at your site?

Best regards
Parag

 

1) Has the Lube Oil consumption on the machine increased? It's possible that you have an internal leak.

2) Has any maintenance been done recently?

3) When did the high w/space temp. start? Can it be associated with any other event/maintenance ?

4) Have you had a look at the IGV and early compressor stages prior to offline wash. If yes, what do you see

 

Dear Parag,

Have you observed lube oil level drops? It could be lube oil leaks from bearing no.1. The leaks may travel into the bell mouth and into compressor and caused compressor blades fouling and efficiency drops.

regards
Fai

 

Dear Parag,

In addition to that was stated above;

1. Have you measured the suction pressure of the GT (after the filters), comparing it also with GT2 to determine whether the cause is the filter assembly or the GT itself?

2. You stated that you have offline/online washing system. Are you operating the online system? If yes, is the quality of the washwater OK? Low quality was will deposit salts on the compressor blades.

3. Is the GT1 exposed to some sort of contaminants in the atmosphere, possibly fouling the compressor, that GT2 may not be picking up, due to the way the site is laid up?

You stated that the GTs are operated in co-generation mode. What is the process that is using the recovered heat/generated steam?