Research On Optimization Control And State Diagnosis Of Utility Boiler Combustion

Coal-fired power generation will be still the most important power generation technology for a long time in China.Changes in resource,environment and climate have serious challenges for sustainable development of coal-fired power generation.In the case of increasing unit capacity,more parameters and more complicated thermal process,research on optimization control and state diagnosis of utility boiler combustion based on measuring the parameters of furnace will offer an effective solution for the operation of coal-fired generating unit with high efficiency and low ermission.This dissertation focuses on the optimization control and state diagnosis of utility boiler combustion based on measuring the parameters of furnace,the main content includes:(1)The boiler furnace parameters which influence power boiler combustion was studied.An analysis was made to the effects of furnace parameters on the efficiency,pollutant emission and service life of a boiler,then the mutual realationship between these parameters and the boiler combustion optimization was researched.A new technology for measurement of furnace parameters based on laser absorption spectrum was described from the aspect of measuring principle and system structure.Taking a coal-fired boiler as an example,the studies of field measurement and reconstruction of furnace parameters were carried out on the boiler based on laser spectrum.(2)The balance control of furnace temperature field of the corner tangential coal-fired boiler was studied,the uneven distribution problems of the furnace temperature field was analyzed,and the effect of furnace temperature field on nitrous oxides generation of boiler were discussed,then a fuzzy self-tuning based PID control strategy is presented for balancing control of furnace temperature field.Firstly,the furnace temperature field image is reconstructed based on the data obtained from the laser spectrum measurement system,and then the center coordinates of the furnace temperature field can be calculated.Depending on distributed control system,the additional correction to each auxiliary air damper opening in each corner was calculated by PID controllers,and then the furnace temperature field can be regulated by changing the volume of auxiliary air in each corner.In the process of temperature field balance control,the parameters of PID controllers were optimized by fuzzy self-tuning method.(3)The combustion optimization in power station based on data-driven case-matching was studied.According to the characteristics of the power plant boiler operation parameters,the thermal parameters which affect the boiler efficiency and nitrogen oxide emissions can be divided into supporting thermal parameters and adjustive thermal parameters according to requirements.Considering dual requirements of improving boiler efficiency and reducing emissions,a boiler combustion optimization method based on data-driven case-matching was proposed.Firstly,by judging the steady state of the historical operating conditions in the historical database according to the supporting thermal parameters,an combustion case library wasbulit off-line.Then,calculating the current operating condition based on real time operation data,by the best match case in the case library was found out to get the optimal parameters value for the current running condition,thus power plant boiler combustion optimization was completed.Compared with the other combustion optimization method,this proposed method has obvious advantages and engineering application value.(4)The evaluation on combustion stability and economy of power plant boiler was studied.The effects of fiurnace parameters on combustion stability and economy of a boiler were analyzed.Based on the data obtained from the boiler laser spectrum measurement system,a fuzzy comprehensive evaluation strategy for the state of boiler combustion was proposed.Then,a secondaryfuzzy comprehensive evaluation model was established.Evaluating the boiler combustion stability and economy was presented from furnace temperature.O2 volume fraction and CO concentratio.On the basis of evaluation result,and in order to complete the evaluation of the combustion state of the boiler more quickly,a support vector machine model for the stability and economy of boiler combustion was developed and verified.Experimental results show that the evaluation of the stability and economy of boiler combustion can be effectively completed by the model proposed under different working conditions with a higher calculation speed,and can be used for providing guidance for online optimization and adjustment of boiler combustion.