Fuel heating in combined cycle turbomachinery

摘要

Combined cycle efficiency can be improved by heating fuel in a gas turbine fuel line (42) in two stages (44,46) using (i) hot water from an HP economizer (32) of a heat recovery steam generator (HRSG) (16) in a second stage and (ii) hot water from an IP economizer (34) of the HRSG (16) and water output flow from the second stage in a first stage. Efficiency may be further improved by adding one or more fuel preheaters (52) using hot water from the IP feedpump (54) and sequential injections of hot water into the fuel.