We have GE frame V MS5001 gas turbines with natural gas as fuel, at our one of gas turbines excessive exhaust spread is being observed at higher loads that is 10MW and higher. could any one suggest what could be the probable causes of that and does the slight leakage or passing of any or both compressor bleed valves contribute to the excessive exhaust spread? and what is the leakage class of compressor bleed valves?

 

How High is your spread? Have you done any maintenance recently? Primary cause of high spreads is usually fuel nozzles. If you have a spare set of nozzles, a change is probably the best course of action to at least eliminate this. Other causes are ingress of CPD around transition piece and liner seals but this is not so common. For the bleed valves, if the leak past is large it could be impacting on the exhaust TC in that area. Where is your low temp. point?

 

Thanks Bob for your reply. Last maintenance job on this machine was carried out in 2007 in which fuel nozzles were changed. most recently to resolve this problem offline water wash was carried out last month but situation did not improve. Low temp area keeps moving with different loads, below are readings of exhaust T/Cs at various loads

At load=3MW TTXD-1=312, 2=310, 3=312, 4=310, 5=308, 6=311, 7=320, 8=312, 9=310, 10=312, 11=309, 12=314, 13=310, TTXSP1=12

At load=4MW TTXD-1=314, 2=312, 3=313, 4=309, 5=310, 6=313, 7=320, 8=311, 9=308, 10=312, 11=310, 12=314, 13=312, TTXSP1=11.2

At load=6.8MW TTXD-1=360, 2=362, 3=361, 4=357, 5=358, 6=364, 7=367, 8=355, 9=354, 10=357, 11=359, 12=362, 13=358, TTXSP1=11.7

At load=9MW TTXD-1=381, 2=384, 3=379, 4=379, 5=378, 6=386, 7=389, 8=376, 9=378, 10=379, 11=381, 12=383, 13=380, TTXSP1=13.3

At load=11.7MW TTXD-1=410, 2=415, 3=404, 4=404, 5=408, 6=423, 7=430, 8=426, 9=420, 10=417, 11=408, 12=405, 13=404, TTXSP1=26.8

At load=14.3MW TTXD-1=380, 2=359, 3=357, 4=374, 5=399, 6=383, 7=375, 8=373, 9=369, 10=366, 11=370, 12=403, 13=377, TTXSP1=42.1

At load=16MW TTXD-1=376, 2=367, 3=375, 4=402, 5=406, 6=395, 7=382, 8=383, 9=375, 10=375, 11=394, 12=406, 13=384, TTXSP1=39.2

 

up to certain extent its not contributor in exhaust high spread. none the less its bergon passing can reveal in low temp of TC directly being cooled by bleed valve passing in exhaust plenum. If its the case you must check out wheel space temp & compare it with normal spread case. if its too high then it can be avert that passing is not ignorable do inspection of bleed valve flapper & seat,

 

> Thanks Bob for your reply. Last maintenance job on this machine was
>carried out in 2007 in which fuel nozzles were changed. most recently to resolve this problem offline water wash was carried out last month but situation did not improve. Low temp area keeps moving with different loads, below are readings of exhaust T/Cs at various loads <


I am having the same problem on MS9001E. At 50MW load the Unit trip on exhaust spread. We have checked the nozzles. Pls what else can be done?

 

I think you need to get a replacement set of fuel nozzles installed before you go any further. The spreads you have shown look typically like bad fuel nozzles and if the existing nozzles have been in service for four years I think this would be simplest way to try and eliminate.
Has this high spread developed over a period of time or did it suddenly appear?

 

in our unit after gas turbine washing tripped during startup due to high exhaust spread once, and on 2nd attempt it synchronize with out any abnormality. plz guide?

it has been going for last two months.