Proposal and Evaluation of Repowering Systems for Utilizing Waste Heat from Small Scale Garbage Incineration Plant

This paper evaluates two proposed repowering systems together with a conventional repowering system. A power generation system utilizing waste heat produced by a garbage incineration plant (GIP), which treats 45 t/d of garbage, was taken as an objective power generation system to be repowered. As the conventional repowering system (Sys-C), a gas turbine system with waste heat boiler was adopted. In the proposed system 1 (Sys-P1), temperature of the low temperature steam generated at the GIP is raised in the gas combustor by burning fuel and used to drive a gas turbine generator. Hence, required power for compressing the air becomes remarkably small compared with Sys-C. In the proposed system 2 (Sys-P2), the low temperature steam generated at the GIP is superheated by using regenerative burner and used to drive a steam turbine generator. Various basic characteristics of the three repowering systems were estimated through computer simulation, such as power generation efficiency, repowering efficiency, energy saving characteristics, and amount of CO₂ reduction. It was shown that Sys-P1 and Sys-P2 were both superior to Sys-C in the all characteristics, and Sys-P1 to Sys-P2 in repowering efficiency, and that Sys-P2 to Sys-Pl in energy saving characteristics and CO₂ reduction effect