Written by Scott Schreeg | Power Plants
Every industrial site carries inherent safety risks that require constant monitoring and control in case of emergencies. Among the various hazards that industrial plant employees encounter is managing gas turbine exhaust systems and stack temperatures to prevent damage, protect employees, and minimize downtime.
How Can Gas Industrial Exhaust Stacks Become Hazardous?
The purpose of a gas turbine exhaust system and stack is to direct the turbine exhaust flow safely to the atmosphere. Turbine exhaust flow is hot and violent, and safety considerations need to be met to direct it away from any plant personnel. A typical turbine exhaust system will include an internal floating liner in the exhaust ductwork and stack. This internally lined system is designed thermally to maintain a safe outer casing temperature for plant personnel. Also usually included in a CT exhaust system are silencers so the exhaust noise from the gas turbine meets permitted site criteria.
Given that the exhaust temperatures can cycle from ambient to, in some cases, over 1200 degrees Fahrenheit, a lot of these materials can fatigue, which leads to cracking and degradation. Therefore, the materials in an exhaust system meant to keep a system safe and quiet compromise the system as they fail. This can result in metal being ejected from the stack. One of the most common pieces of material that can crack and become airborne is the silencer perforated sheets. Silencer cavities have insulation for acoustical purposes, providing absorption, and the perforated facings provide an open area so they can function as designed. However, it is not uncommon for the perforated facing to come detached and crack and have pieces of perforated steel exhausting out of the stack.
How Does a Stack Screen Help Minimize Downtime and Increase Safety?
Even if a plant is conducting routine inspections at its outages, the cracking of these materials can happen quickly and become a safety issue almost overnight. Plants want to avoid forced outages and unplanned outages, and considering that the exhaust system may need new silencers if they are past the point of repair, the lead time can be problematic for near-term replacement. In an effort to contain any materials, avoid any safety issues, and be able to run until new equipment can be designed and supplied for a future outage, one option could be to install a stack screen.
A stack screen does not fix the root cause of the problem, but it can help the site operate safely until a retrofit is properly planned for a future outage. The stack screen construction consists of structural framing designed to match the geometry at the top of the stack. It utilizes a heavy wire screen installed on the frame, designed to keep larger, more dangerous metal pieces from being ejected while only having a negligible impact on pressure drop for the system. Depending on customer preference, these screens can be designed to be bolted or welded to the stack.
SVI-BREMCO Can Help with Gas Turbine Exhaust Systems and Stacks
Stacks don’t always become compromised and have loose material being ejected. However, when it does happen, there is a risk of having to shut down the plant for repairs. Maintaining acceptable temperatures is essential for your gas turbine exhaust system and stack to help prevent that. At SVI-BREMCO, we can help you meet that requirement and keep your employees safe. Our team is available to come to your site and provide an inspection to determine if you have any thermal issues that need to be addressed.
If you have any problems with excessive temperatures in the exhaust system, we can design and install a liner system to meet your temperature goals. If you are currently experiencing debris being ejected from your stack, it’s crucial that you contact SVI-BREMCO to mitigate the problem. We will determine the best solution for the plant and your workers, whether it is a stack screen or something else.
If you want to learn more about our services, please contact us with any questions today.