Optimization Of Ultra-low Emission System Of Coal-fired Power Plants Based On CO Method

As the continuous improvement of environmental protection requirements,the ultra-low emission system of flue gas from coal-fired power plants plays an increasingly important role in the whole thermal power system.The ultra-low emission system is mainly composed of four devices:selective catalytic reduction device,wet flue gas desulfurization device,electrostatic precipitator and wet electrostatic precipitator,and the devices can synergistic remove the same pollutant.It is a complex optimization problem with multiple models and constraints.Multidisciplinary design optimization is often used to optimize engineering problems with multi-model complex constraints.As an advanced decentralized solution strategy in multidisciplinary design optimization,collaborative optimization decomposes the problem into two-level optimization structure,which greatly reduces the complexity of the problem.Therefore,it is of great significance to apply collaborative optimization to the optimization of ultra-low emission system.The main research contents of this paper are as follows:(1)Aiming at the problem that traditional collaborative optimization is sensitive to initial point and easy to converge to local best,a global stable optimization collaborative optimization method is proposed.Dynamic penalty function is adopted at the system-level to transform the system-level optimization problem into unconstrained optimization problem,which expands the feasible optimization domain and enhances the global optimization ability of the system objective function.At the discipline-level,the original objective function of the discipline is combined into the discipline-level objective function in the way of dynamic weighting.While seeking consistency in the process of optimization,the influence of the original objective function of the discipline on the optimization of the discipline is taken into account to expand the scope of the optimization of the discipline.Finally,the method is verified by two typical examples and compared with other collaborative optimization methods.The results show that the improved method has better optimization performance and stronger stability.(2)By analyzing the mathematical models of each device in the ultra-low emission system,this paper constructs an optimized framework for the ultra-low-row synergy removal of flue gas based on the improved collaborative optimization method.The original system is decomposed into three parts:denitrification discipline,desulfurization discipline and dust removal discipline under the framework of improved collaborative optimization method.At the same time,the export concentration of pollutants was taken as the main constraint condition,and the operating cost of the system was taken as the optimization objective.Taking several typical working conditions as simulation examples,the improved collaborative optimization method was used to optimize the system and compared with the overall particle swarm optimization and independent optimization.The feasibility and effectiveness of the improved collaborative optimization in ultra-low emission system were proved.