Diffusion Bonded Heat Exchangers (PCHEs) in Fuel Gas Heating to Improve Efficiency of CCGTs

Abstract

The purpose of this paper is to show how compact heat exchanger technology can offer energy savings and hence cycle efficiency improvements on new and existing gas turbine installations by being utilised for fuel gas heating. After a brief introduction to high temperature compact heat exchanger technology and comparison to traditional equipment, thermodynamic cycle analysis for a combined cycle gas turbine plant (CCGT) is used show the advantages of compact technology over conventional technology, analysing the fuel gas heating, to illustrate the overall savings. A case study is used to demonstrate an increase in net LHV electric efficiency in the range of 0.5 to 1.17 % achievable using high effectiveness compact diffusion bonded heat exchangers in fuel gas heating. Intermediate pressure and high pressure feed water heating is considered for increasing the fuel gas inlet temperature to the combustor. The model is built in Excel and is extended to a capital expenditure overview based on new or a retrofitting in existing plants.