Exhaust Gas Emission Improvements of Water/Bunker C Oil-Emulsified Fuel Applied to Marine Boiler

In this study, emulsified fuels were prepared and produced by blending 0%, 5%, 15%, and 25% water with Bunker C oil to reduce the amount of air pollution emitted by ships and replace oil resources, and they were applied to an actual marine boiler to analyze the exhaust gas. The fuel effects on the improvement in exhaust gas emissions were as follows: The oxygen (O2) concentration increased by up to 4.2%, and that of carbon dioxide decreased by approximately 2.1%. Under the standard O2 concentration of 4%, the concentration of nitrogen oxides decreased by up to 31.41%, and that of sulfur oxides decreased by up to 37.47%. However, the exhaust gas temperature decreased by approximately 14.3%, and the combustion efficiency decreased by approximately 2.6%. Comparing the emission improvements, the combustion performance of the emulsified fuels was close to that of the conventional Bunker C fuel. These results indicate that the application of water-emulsified fuels to a marine boiler can reduce the amounts of certain air pollutants.

An Intelligent Bio-Inspired Cooperative Decoupling Control Strategy for the Marine Boiler-Turbine System with a Novel Energy Dynamic Model

This paper presents an intelligent bio-inspired cooperative decoupling control strategy (IBICDC) for the problems of modeling difficulties and strong coupling in the marine boiler-turbine system (MBTS). First, the model of the main steam pressure control loop is successfully constructed by introducing the Martin-Hou equation, which solves the modeling difficulty caused by the complexity of structure, operation mechanism, and operation conditions, as well as the characteristics of nonlinearity, parameter time-varying, and time-delay in the marine boiler (MB). According to the mathematic method of homeomorphic mapping relationship between the rotational speed and the kinetic energy in the marine steam turbine with propeller (MSTP) and the feedback linearization method, the nonlinear degree of the MSTP rotational speed control loop model is reduced and the infinite point of discontinuity in the rotational acceleration when the rotational speed close to 0 is eliminated. Then, the IBICDC inspired by the internal environment regulation mechanism of human body is applied to the strong coupling problem between the two control loops, namely, to eliminate the large value sudden change of the main steam pressure caused by the change of operation conditions. The conventional decoupling methods are also presented. Finally, detailed numerical simulations are conducted to validate the effectiveness of the IBICDC strategy.