Research On Simulation For Combustion Of Boiler

As the world economic is growing, the coal resource utility has been more critical than ever. It is of significance to improve the combustion control system of the power plant for high boiler efficiency and energy reservation as well as economic efficiency, because the boiler has complicated structure, heavy hot capacity and big delay and inertia. In addition, the difficulty of measuring the flow of fuel accurately, and the quality of the fuel is changeable. The vapor pressure control subsystem in use is very difficult to overcome fuel disturbance effectively in time. It is difficult to guarantee the stability of the combustion, influence the security and operation economically.First of all, the structures that make up the whole control system and their function were studied in this paper. Then the unit dynamic properties and the cunctation were analyzed chiefly, and the load dynamic properties as well as the main steam pressure cunctation were studied. To deal with the limitation of the conventional feedback signal, a radiant energy signal which could reflect the change of the fuel rate or the quality of combustion more directly was proposed to optimize the combustion control system.An adjusting system of boiler combustion based on the radiant energy is adopted. Through comparison with several traditional control systems of boiler combustion, the combustion control system with the main steam pressure as the primary adjusting parameter and the radiant energy of the furnace chamber as the subsidiary parameter was put forward. A parameter self-regulation fuzzy-PI controller was designed as outer loop. The controller automatically corrected the quantizing factors and proportional factor through compiling S-function to improve the properties of the basic fuzzy controller, then combined fuzzy control with PI control to optimize the control system. Simulation result shows the project is effective to control nonlinear and big-lagged system.To solve the problem that the mathematic model of the controlled object is not steady when the controlled object changes, a new control plan based on the H∞mixed sensitivity was put forward for combustion H∞control system. By choosing proper weighting function, the robust toolbox was used to obtain the H∞optimal controller In order to compare and analyze the properties between the original system and the improved system, the research analyzed both system in use of the toolbox of SIMULINK of MATLAB, the conclusion expressed the improved system worked better, the improved system can overcome the disturb more better than the original system, decrease the delay and the inertia, the improved can decrease the use of energy in power plant and improve the economy of the plant.