Specification of Circulating Fluidized Bed (CFB) and Steam Turbine Generator of Heat Recovery System for Marine Diesel Engine

概要

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In 21st century, ship energy system has to be updated not to consider only less fuel consumption but also emission control of NOx, SOx, and CO2 from marine diesel engine. For domestic ship, we proposed new concept of exhaust heat recovery system, consisting of circulating fluidized bed (CFB), and hi-speed radial steam turbine generator. This CFB is smaller than commercial CFB plant and has two-function: heat recovery from exhaust gas and desulfurization by choosing suitable particle. In this report, parameter survey about the CFB and the steam turbine-generator, which are main components of the system, was executed. Supposing water tubes located along riser of the CFB, specification of the CFB like particle diameter and exhaust gas velocity inside the riser, was evaluated to equilibrate the two-functions and gas-particle fluidization. The system was required to add external heat exchanger at upstream of exhaust gas flow, to produce higher superheated steam, in purpose of generating more power output by the radial turbine, based on the evaluation. Furthermore, steam temperature and pressure at inlet of 1st steam turbine-generator, and expansion ratio of all turbines were adjusted to gain more electrical power by increasing degree of superheat. As a result, maximum power became 9.48% of main engine power, in 75% loading factor of 1400kW-class marine diesel engines.