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How to check whether the Compressor Blow Off Valve is passing or not for GE 9FA machine? What is the indication if Compressor Blow off valve is Passing? i.e CPD drops, CTD temps drops....
Most 9FAs that I've seen P&IDs for have multiple compressor <b>bleed</b> valves, as in four (4).
If a compressor bleed valve is passing (leaking) severely enough then the CPD will likely be lower than normal.
If a compressor bleed valve is not fully closed during normal operation, then the piping downstream of the valve will be hot, hotter than normal. Most sites with F-class units use non-contact thermal sensors ("heat guns") to check the temperatures of the piping downstream of the compressor bleed valves.
If a compressor bleed valve is passing (leaking) severely enough then the CPD will likely be lower than normal.
If a compressor bleed valve is not fully closed during normal operation, then the piping downstream of the valve will be hot, hotter than normal. Most sites with F-class units use non-contact thermal sensors ("heat guns") to check the temperatures of the piping downstream of the compressor bleed valves.
P
Paragkumar
> Most 9FAs that I've seen P&IDs for have multiple compressor <b> bleed</b> valves, as in four (4).
> If a compressor bleed valve is passing (leaking) severely enough then the CPD will likely be lower than normal.
> If a compressor bleed valve is not fully closed during normal operation, then the piping downstream of the valve
> will be hot, hotter than normal. Most sites with F-class units use non-contact thermal sensors ("heat guns") to check
> the temperatures of the piping downstream of the compressor bleed valves.
Dear Sir,
We are also experiencing the same problems. we are operating GE frame 7FA DLN 2.6 Gas turbines. recently we have completed Major Inspection on two units. we have refurbished the bleed v/v and its complete assembly. after MI, once we started the unit and it reached to base load, we have measure the bleed v/v upstream and down stream temperatures and found two bleed v/v passing.
As the both units ( GE 7FA ) came online after MI, we compared boht units on base load
unit#01 160 MW ( 2 bleed v/vs passing )
Unit#02 168 MW
and we have been running unit#01 with bleed v/v opened since last 5 days
I suspect if we run continue like this it may affect the hot gas path parts ( as in GT 80% air is used for cooling the Hot gas path parts ), and currently air is bypassing to the exhaust through leaky bleed v/vs
what are the consequences to run the GT with bleed v/v open in longer run?
Appreciate your help to understand the affects
Thanks & regards
KKK
> If a compressor bleed valve is passing (leaking) severely enough then the CPD will likely be lower than normal.
> If a compressor bleed valve is not fully closed during normal operation, then the piping downstream of the valve
> will be hot, hotter than normal. Most sites with F-class units use non-contact thermal sensors ("heat guns") to check
> the temperatures of the piping downstream of the compressor bleed valves.
Dear Sir,
We are also experiencing the same problems. we are operating GE frame 7FA DLN 2.6 Gas turbines. recently we have completed Major Inspection on two units. we have refurbished the bleed v/v and its complete assembly. after MI, once we started the unit and it reached to base load, we have measure the bleed v/v upstream and down stream temperatures and found two bleed v/v passing.
As the both units ( GE 7FA ) came online after MI, we compared boht units on base load
unit#01 160 MW ( 2 bleed v/vs passing )
Unit#02 168 MW
and we have been running unit#01 with bleed v/v opened since last 5 days
I suspect if we run continue like this it may affect the hot gas path parts ( as in GT 80% air is used for cooling the Hot gas path parts ), and currently air is bypassing to the exhaust through leaky bleed v/vs
what are the consequences to run the GT with bleed v/v open in longer run?
Appreciate your help to understand the affects
Thanks & regards
KKK
Dear Paragkumar,
I am not suggesting that it is a good idea to continue running with compressor bleed valves that are leaking or are not fully closed.
But I do not believe that you should be concerned about damage to the hot gas parts. The loss of compressor air through the bleed valves will reduce the CPR, compressor pressure ratio, which will reduce the air for combustion and for exhaust flow. This loss of exhaust flow will raise the exhaust temperature and will reduce the total output of the machine by limiting fuel for combustion. But since the loss of air is raising the exhaust temperature and that is how the machine is controlled then no damage to machine hot gas parts should occur.
Hopefully the bleed valves are not damaged, it may be a simple fix of adjusting the stop bolts allowing the valve to close fully. The problem should be identified so parts and a shutdown can be scheduled before these valves are damaged beyond repair, I do not think they were designed to be passing hot compressor air for long periods(days) of time. Someone has to make the choice to run and lose power output and risk damage to the very expensive bleed valves, or shutdown and repair the problem. But I would not be overly concerned about hot gas path part damage, the control algorithms and sensors should protect these parts.
I am not suggesting that it is a good idea to continue running with compressor bleed valves that are leaking or are not fully closed.
But I do not believe that you should be concerned about damage to the hot gas parts. The loss of compressor air through the bleed valves will reduce the CPR, compressor pressure ratio, which will reduce the air for combustion and for exhaust flow. This loss of exhaust flow will raise the exhaust temperature and will reduce the total output of the machine by limiting fuel for combustion. But since the loss of air is raising the exhaust temperature and that is how the machine is controlled then no damage to machine hot gas parts should occur.
Hopefully the bleed valves are not damaged, it may be a simple fix of adjusting the stop bolts allowing the valve to close fully. The problem should be identified so parts and a shutdown can be scheduled before these valves are damaged beyond repair, I do not think they were designed to be passing hot compressor air for long periods(days) of time. Someone has to make the choice to run and lose power output and risk damage to the very expensive bleed valves, or shutdown and repair the problem. But I would not be overly concerned about hot gas path part damage, the control algorithms and sensors should protect these parts.
