The Research Into The Combustion Control System Of Marine Main Boiler

This paper is aimed at studying and designing a new combustion control system according to the motion traits of marine main boiler and demands on combustion control system.First, the working principles of the combustion control system of marine main boiler in present use and its disadvantages are discussed in the paper; in the light of the structure and motion traits of marine main boiler, the combustion control systems of single and double cross amplitude limits are designed. At the same time, the schematic diagram of system and recovery curves of some relative parameters are given, the system working principles and its advantages and disadvantages are discussed. Based on the combustion control system of dual-crisscross amplitude limit, by selecting the independent variable , the fixed offset is improved into variable offset , the combustion control system of variable offset dual-crisscross amplitude limit is designed. In addition, the system schematic diagram and recovery curve of some relative parameters are given, meanwhile, the relational expression between the positive and negative offset functions of air pressure and fuel flow and variable offset polygonal functions are given. The system inherits the advantages of the combustion control systems of single and double cross amplitude limits, having overcome the disadvantages. It not only guarantees the system response performance of change in load, but also takes into account the economic performance of the system. Second, the main boiler combustion coordinated control system in present use in the coordinated control system of marine steam turbine and boiler, to counter the system advantages and disadvantages are introduced and discussed in the paper. Aiming at the disadvantages of marine main boiler combustion adjust control system now, the system has been improved and designed. The design schematic diagram of the system and the principle designing curves of polygonal functions are given, the transfer functions in some relative segments of steam turbine and boiler coordinated control system are deduced,analyzing the system working principles. The steam turbine and boiler coordinated control system which has been improved and designed inherits the advantages of the original one and overcomes the disadvantages of it. Finally, for the designed combustion control system and steam turbine and boiler coordinated control system, by closed-loop experiments, it is proved that the variable offset dual-crisscross amplitude limit combustion control system is reasonable and the function of steam turbine and boiler coordinated control system in reducing the main steam pressure dynamic warp is tested. By emulational experiments, the best domain of some relative control parameters and variable offset parameters in variable offset dual-crisscross amplitude limit combustion control system is given. The results can be used for control system in a real ship, also when it is debugging.