Cogenerative combined cycle power plants fueled by coal and biomass gas

This paper proposes a system made-up by a Lurgi fixed-bed gasifier fed with coal or biomass and by a dual pressure level gas-steam combined cycle power plant in cogenerative application. Some comparisons among different configuration plants with single or double intercooled compression gas turbine are carried-out. In this analysis gas turbine off-design operating conditions, due to the use of low-medium Lower Heating Value coal or biomass gas fuel, are pointed-out. A constrained minimization algorithm is used for solving simultaneously all equations describing the system (included the ones representing energy balances and chemical equilibrium in the gasifier) to calculate the integrated plant performance. Results show that the proposed plant can work with energy conversion efficiency not much lower than the one obtainable when the gas turbine is fed with methane, that is the fuel for which the gas turbine itself was designed. Nevertheless, increases up to 15% in both electrical and thermal power are evaluated.