headsUP: Exhaust silencers

When did you last check the exhaust silencers?

David Clarida, Integrity Power Solutions

Clarida is knowledgeable about inlet and exhaust systems for gas turbines. He had years of experience in the design, installation, and maintenance of front and back ends for aeros and frames with GE Energy and Braden Manufacturing LLC before launching Integrity Power Systems (IPS) a couple of years ago. See Clarida’s artcle in CCJ, How to inspect, replace GT exhaust system components.

Recently, IPS and Willbros Downstream Field Services—a well known in the oil patch and looking to grow in power generation—established a strategic alliance for GT inlet and exhaust work. Clarida suggested that one area users might be overlooking in annual inspections today is the condition of exhaust silencers.

Noise is becoming more a concern as eco-friendly gas-fired plants are located closer to load centers. A little inspection and maintenance goes a long way in avoiding noise complaints from neighbors.

Clarida said exhaust silencers can be installed in horizontal ductwork just ahead of the stack breeching or in the stack proper and a visual inspection for condition is relatively easy. He suggested checking the stack periodically on startup to see if insulation is present; also, examining the perforated plates to verify their integrity. What happens is the high-velocity exhaust gas stream sucks insulation out of the silencer and as the quantity of insulation decreases, the metal suffers thermal damage conducive to failure.

It’s rare that an owner/operator pays much attention to exhaust silencers, so it should not be a surprise that the low-bid offshore supplier might use thinner gauge steel than the spec calls for and not do much in the way of fabrication quality control. Unlikely that the intended design lifetime will be achieved.

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