| Pollution made by NOx emission has influenced people’s daily life and work, it isurgent to reduce NOx emission. The main methods of reducing NOx in coal-fired powerplants are equipping denitration facilities (such as SCR or SNCR) and combustionadjustment, but the former has high initial investment and operating cost. Combustionoptimization has low cost, less investment of manpower and material resources and inaddition, it has obvious effect of denitration.It is helpful to reduce NOx emission and increase boiler efficiency by match airvolume and coal precisely in different combustion state. The air and coal adjustingmechanism of coal-fired boiler are independent respectively, but the traditionalcombustion control system can only insure the precisely matching of total air and coal,and can not give play to the advantages of independent adjusting mechanisms, so it is notable to adjust the ratio of air and coal, the center of flame, the shape of secondary airprecisely, which have important influence on boiler efficiency and NOx emission.According to data of combustion adjustment experiments and thermodynamiccharacteristics and laws, proposed combustion optimization control system combiningfeedforward and feedback control method, aiming to adjust excess air coefficient,primary air pressure, secondary air pressure, each coal feed amount, each temperature ofmill outlet, each primary air volume, each secondary air volume and over fire air in alloperation states specifically, dynamically and precisely, in order to gain the best excessair coefficient, the optimum shape of secondary air and the optimal center of flame.During the implement process, built a Simulation platform in Matlab verifying theoptimization control system, and transplanted it to actual DCS in case of insuring thefeasibility of the new control system. Put the optimization control system into operationand analyzed the data, guaranteeing the boiler efficiency, combustion optimizationcontrol system can reduce NOx emission efficiently. |
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