A novel design of heat recovery system from exhaust stacks’ silencers in a simple cycle gas turbine

This paper aims to evaluate the potential of heat recovery from the integrated heat exchanger within the exhaust stack silencer baffles in a simple cycle gas turbine. Heat transfer channels were incorporated into the upstream (nose) and downstream (tail) sections of the parallel silencer baffles in the exhaust stack. The gas turbine exhaust gas represents the hot side flow across the baffles' sections. The integrated heat exchanger system offered an advantage of extracting waste heat from the exhaust stream, while reducing pressure drop on the flow and improving acoustic attenuation.

In this work, a series of parametric studies were carried out across a range of internal and external heat transfer area configurations within the silencers to maximize the heat transfer. Further enhancement opportunities were introduced and discussed based on the conducted parametric studies and practical aspects borne out of common industry practice. The proposed heat recovery system was implemented to power the gas fuel performance heater which is used to enhance the gas turbine cycle performance through utilization of the extracted waste heat while keeping lower exhaust pressure drop in the stack.

The obtained results showed that the proposed integrated heat exchanger within the silencers has a potential of generating a 5.48 MW net gain from the gas turbine exhaust stacks which are normally lost to the atmosphere from the simple cycle exhaust stack. The proposed heat recovery system proved significant fuel savings that lead to economic benefits and reduction in CO2 emissions.