Analytical study of power generation efficiency of WtE systems operating in Tokyo special ward district

This paper attempts to present a fundamental system analysis for the performances of currently operating waste-to-energy incinerators in Tokyo special ward district. Firstly, it is stated that the gross thermal efficiency η _G of any steam turbine generation system could be expressed as a product of four parameters: the boiler efficiency η _b, turbine steam utilization fraction R _t, heat cycle constant R _h, and turbine generator chamber efficiency η _tg. Secondly, reliable heat inputs to waste-to-energy systems were established by the ideal boiler efficiencies η _b,ids which are based on the versatility of the standardized combustion gas properties, to avoid totally depending on the conventional low calorific value measurements of the fed-waste which occasionally include dubious results. Thirdly, the achievement of technological progress of power generation in waste-to-energy systems over the past 3 decades was reviewed. The advantage of 4 MPa class incinerators (installed after 2001) over 3 MPa class incinerators (installed before 1999) in η _G by 33.1% on average was clarified. Fourthly, the difference in operational modes which affects the η _G was studied to seek for the optimum operation in terms of energy recovery. In conclusion, this paper evaluated that the overall η _G of the 20 incinerators in FY2015 proved to be 15.0%.