Masahide Takagi

Conceptual Design of Power Generation System Utilizing Heat from Exhaust Gases of Marine Diesel Engine

Exhaust gas economizers have been installed on a wide range of ships, for better fuel oil economy; since the oil crises of the 1970s. After the turn of the century, the pressure improve the fuel economy further, as well as to protect the environment markedly increased. The authors propose a concept for a power generation system, for domestic ships, to substantially improve fuel oil economy. Also, reduce SOx emissions by utilizing the rejected heat of exhaust gases from marine diesel engines. As a heat exchanging device, a circulating fluidized bed, here a mixture of the exhaust gas and fine, desulphurization solid particles circulate. This for reason of higher overall heat transfer coefficients and the quality to reduce sulphur-oxides emissions through a dry desulphurization process, in the fluidized bed. As an electric power plant, a radial steam turbine was integrated with a high speed dynamo, this selected because of a higher energy conversion rate. This technology is based on the micro gas turbine. A preliminary estimate indicates that an electric power of 80 to 100 kW will be recovered from the exhaust gases, and at the loading factor of 75 % for 1500kW-class marine diesel engines.

Alternative Index for Compliance Verification of NOx Emission Value through On-board Nox Monitoring

The NOx Technical Code under the MARPOL 73/78 Convention ANNEX 6 specifies the NOx emission limits and has determined the direct measurement and monitoring method for the on-board NOx verification procedure. But the monitoring method might not have been established yet, since it is reported that some results of NOx emission values measured on board exceed the 15% allowance even in the case of engines with certification. Since there are several constraints in the measurements on board, the uncertainty is enhanced comparing to the measurements at a shop-test. In this report an alternative index is proposed to reduce the uncertainty and simplify the on-board measurement. The index is named as NOx 13 that is normalized with oxygen concentrations and contains the correction factor for humidity and temperature. The NOx emission value, NOx [g/kWh], is theoretically correlated to the NOx13 as in the following expression and the correlation is experimentally confirmed.NOx [g/kWh] = α1×α2× be [g/kWh] × N0x13 [ppm]α1, α2; constant, be [g/kWh] ; specific fuel consumption