I have recently been doing work on GE 7F.05 simple cycle exhaust systems and have just found the second of three systems with failed exhaust silencer panels. Has anyone else been running into this issue? These are relativity new units that should not be experiencing these failures this soon.

 

See attached pictures

 

LQ1,

I really can't see much in the photo; and there's only one photo that I see. Are these panels installed in the hot gas path designed to muffle exhaust sounds, or are they pieces of the insulated side walls of the duct work which have come loose?

Were the exhaust components provided by GE? Is this a diverter damper arrangement used to deflect hot exhaust gases from the inlet to the HRSG and to a simple cycle exhaust stack?

Were these on the same site? Different sites?

I have not been to that many F-class sites with simple cycle exhaust stacks, or even with diverter dampers. I honestly don't recall silencer panels in the exhaust path to muffle exhaust sounds.... Doesn't mean they aren't used on some sites (especially in areas where there is some kind of noise restriction or regulation).

I have seen this before on smaller GE machines, when the side walls had been damaged by high-velocity exhaust gases which had worked their way behind the sheetmetal, blowing insulation out and damaging the sheetmetal. There was never really a consensus as to why the damage occurred. But the replacement sheetmetal had more overlap along the edges and more points of attachment to the outer shell for stability, and it seemed to stop the problem.

The only exhaust silencers I've ever seen that were damaged were damaged by rust (yes, rust of stainless steel components) and it was dangerous to be around the exhaust when the unit was running because small--and medium and large--chunks of perforated stainless steel would be blown out of the exhaust stack (which was only 50 feet tall) and rained down on the site, and cars and people and buildings. (And, the Customer tried to blame the rusting and deteriorating silencer panels on the Mark V which had just been installed to replace the previous Mark II turbine control panels. Yep; the Mark* was blamed yet again, because the units hadn't (couldn't because of neglect) run for a few years prior to the turbine control panel upgrade, and no one had known of the rust and corrosion prior to being able to run the units after the Mark Vs were installed. So, it had to be caused by the Mark*, right? That was the owner's position, and all work on site was shut down for four weeks while people came to investigate and actually write reports that said the Mark* had caused the safety problems (sharp pieces of rusty metal falling from the sky when the units ran. Yep; just another time the Mark* was blamed for problems it had nothing whatsoever to do with.)

Oh, I'm reminded this is a controls-related forum.... Is there some insinuation that the damage shown in the photo is caused by the Mark*????

Enquiring minds want to know.

 

LQ1,

I really can't see much in the photo; and there's only one photo that I see. Are these panels installed in the hot gas path designed to muffle exhaust sounds, or are they pieces of the insulated side walls of the duct work which have come loose?

Were the exhaust components provided by GE? Is this a diverter damper arrangement used to deflect hot exhaust gases from the inlet to the HRSG and to a simple cycle exhaust stack?

Were these on the same site? Different sites?

I have not been to that many F-class sites with simple cycle exhaust stacks, or even with diverter dampers. I honestly don't recall silencer panels in the exhaust path to muffle exhaust sounds.... Doesn't mean they aren't used on some sites (especially in areas where there is some kind of noise restriction or regulation).

I have seen this before on smaller GE machines, when the side walls had been damaged by high-velocity exhaust gases which had worked their way behind the sheetmetal, blowing insulation out and damaging the sheetmetal. There was never really a consensus as to why the damage occurred. But the replacement sheetmetal had more overlap along the edges and more points of attachment to the outer shell for stability, and it seemed to stop the problem.

The only exhaust silencers I've ever seen that were damaged were damaged by rust (yes, rust of stainless steel components) and it was dangerous to be around the exhaust when the unit was running because small--and medium and large--chunks of perforated stainless steel would be blown out of the exhaust stack (which was only 50 feet tall) and rained down on the site, and cars and people and buildings. (And, the Customer tried to blame the rusting and deteriorating silencer panels on the Mark V which had just been installed to replace the previous Mark II turbine control panels. Yep; the Mark* was blamed yet again, because the units hadn't (couldn't because of neglect) run for a few years prior to the turbine control panel upgrade, and no one had known of the rust and corrosion prior to being able to run the units after the Mark Vs were installed. So, it had to be caused by the Mark*, right? That was the owner's position, and all work on site was shut down for four weeks while people came to investigate and actually write reports that said the Mark* had caused the safety problems (sharp pieces of rusty metal falling from the sky when the units ran. Yep; just another time the Mark* was blamed for problems it had nothing whatsoever to do with.)

Oh, I'm reminded this is a controls-related forum.... Is there some insinuation that the damage shown in the photo is caused by the Mark*????

Enquiring minds want to know.

LQ1,

I really can't see much in the photo; and there's only one photo that I see. Are these panels installed in the hot gas path designed to muffle exhaust sounds, or are they pieces of the insulated side walls of the duct work which have come loose?

Were the exhaust components provided by GE? Is this a diverter damper arrangement used to deflect hot exhaust gases from the inlet to the HRSG and to a simple cycle exhaust stack?

Were these on the same site? Different sites?

I have not been to that many F-class sites with simple cycle exhaust stacks, or even with diverter dampers. I honestly don't recall silencer panels in the exhaust path to muffle exhaust sounds.... Doesn't mean they aren't used on some sites (especially in areas where there is some kind of noise restriction or regulation).

I have seen this before on smaller GE machines, when the side walls had been damaged by high-velocity exhaust gases which had worked their way behind the sheetmetal, blowing insulation out and damaging the sheetmetal. There was never really a consensus as to why the damage occurred. But the replacement sheetmetal had more overlap along the edges and more points of attachment to the outer shell for stability, and it seemed to stop the problem.

The only exhaust silencers I've ever seen that were damaged were damaged by rust (yes, rust of stainless steel components) and it was dangerous to be around the exhaust when the unit was running because small--and medium and large--chunks of perforated stainless steel would be blown out of the exhaust stack (which was only 50 feet tall) and rained down on the site, and cars and people and buildings. (And, the Customer tried to blame the rusting and deteriorating silencer panels on the Mark V which had just been installed to replace the previous Mark II turbine control panels. Yep; the Mark* was blamed yet again, because the units hadn't (couldn't because of neglect) run for a few years prior to the turbine control panel upgrade, and no one had known of the rust and corrosion prior to being able to run the units after the Mark Vs were installed. So, it had to be caused by the Mark*, right? That was the owner's position, and all work on site was shut down for four weeks while people came to investigate and actually write reports that said the Mark* had caused the safety problems (sharp pieces of rusty metal falling from the sky when the units ran. Yep; just another time the Mark* was blamed for problems it had nothing whatsoever to do with.)

Oh, I'm reminded this is a controls-related forum.... Is there some insinuation that the damage shown in the photo is caused by the Mark*????

Enquiring minds want to know.

The picture provided is looking down into the stack from a lift basket. At the top of the picture is a silencer panel still in place with exposed insulation were a perforated sheet is loose. These panels are installed in the gas path and are design to attenuate sound. In the bottom of the stack are two mostly intact panels and debris from another panel. The damage was not caused by the control system. I believe it was caused by improperly designed silencer panels. This is a fairly standard exhaust configuration for a large frame GE simple cycle unit that could be converted into a combined cycle unit in the future.

 

LQ1,

Who provided the panels? Did GE provide them, and were they drop-shipped to site from the manufacturer? Or, did the A/E for the power plant provide the exhaust equipment?

GE is not as well-known as it should be for cost reduction moves. It's possible their sourcing people picked a new low-cost supplier and this is the result. It's happened before, and to other manufacturers as well. There is no shortage of vendors who want to sell equipment to GE, and to A/E's building power plants.

I did see one exhaust silencer which broke the "channel" it was slid into and fell down into the bottom of the exhaust stack. In that case, it was clearly the welds on the support channel which were not up to snuff, and only on one side, but enough to cause the failure.

 

I have 4 frame 7ea that are located in area that the locals did not want the plant to be built.

To appease them we installed stack silencer.

Junk!!! I will try to find the vendor and metal supplier. Have replaced the silencers at least once.

Sorry, for the quick and short but in the middle of a major on 2 of the units listed above

 

P.S. We have other units with a standard stack NO PROBLEMS with them.