Abstract
Improvement of a ship's energy system is required for better fuel oil economy and environmental sustainability. The authors proposed a concept of heat recovery system from exhaust gas for a marine diesel engine. Core device of the system is a circulating fluidized bed (CFB) heat exchanger with desulfurization function. In this report, adjustments to the "Circulation Type", in which a condenser was added, were evaluated to gain more electrical power generated from the exhaust gas heat. Analysis of the "Circulation Type" connected to a 1400kW 4-stroke marine engine showed that the maximum electrical output of "Circulation Type A" system, consisting of the CFB and a steam-turbine generator, was 2.96%at 75%-loaded power in the engine. On the other hand, the maximum electrical output for "Circulation Type B" system, consisting of the CFB, a superheater and two generators, and "Circulation Type C" (preheater was added to "Circulation Type B") was up to 8.47%, and 9.20%, respectively. In addition, net electrical output, total heat transfer surface, and total volume of heat transfer regions at each system were also estimated. The total volume estimation in particular, showed that the CFB contributed to the miniaturization of the waste heat recovery system.
