Modeling Of Biomass Circulating Fluidized Bed Combustion System And Research On Unit Energy Storage

Due to the promotion of biomass circulating fluidized bed boiler power generation and cogeneration technology,biomass,as a "zero carbon emission"clean energy,has a good development prospect.Therefore,it is more necessary to explore its combustion characteristics and calculate the available energy storage.In order to analyze the internal combustion mechanism of biomass circulating fluidized bed boilers and facilitate combustion control optimization,the combustion process and combustion mechanism in the furnace are analyzed through the analysis of biomass fuel characteristics and its fluidized process in the furnace,as well as the application of carbon combustion theory.A combustion process mechanism model is established to analyze the dynamic changes of carbon combustion in the furnace,and to achieve the analysis of load,bed temperature Prediction of carbon monoxide emissions and oxygen content in flue gas.In terms of combustion system modeling,the heat storage of the unit is analyzed,and the unit combustion system model,bed material heat storage model,namely,carbon burning heat storage model,and boiler heat storage model are established.The calculation methods for boiler heat storage and condensate throttling heat storage are given,and the relevant calculations for the utilization of energy storage are conducted.Various methods and theoretical efficiency of energy storage utilization are proposed,and control strategy optimization based on energy storage utilization is given.The results show that after the volatilization of the incoming fuel,the formation of ready-to-burn carbon is slower than’ that of the volatile component,and the fluctuation of the feed directly affects the amount of ready-to-burn carbon in the furnace;That is,the combustion of carbon as the main source of heat during feed fluctuations requires less oxygen for combustion,resulting in fuller combustion.At this time,the emission of carbon monoxide in the flue gas is lower and the oxygen content is higher;The predicted values of bed temperature,load,carbon monoxide,and flue gas oxygen content have similar trends to the actual values.Changes in fuel density,water content,and unstable combustion and feed rates in the furnace are the main characteristics of biomass circulating fluidized beds,and are also the main reasons for affecting the prediction accuracy of the model.The heat storage coefficient of the boiler reaches 682.32 MJ/0.4MPa;Bed material heat storage and instant combustion carbon heat storage are mainly used to maintain combustion stability and boiler thermal load stability;that is,carbon combustion plays a key role in supporting the thermal load when the feed is significantly reduced.The combustion rate can be increased to 2-3 times,and the total amount of instant combustion carbon in the furnace is about 800 Kg.Due to the impact of combustion consumption,the fluctuation between up and down is large,and the fluctuation of instant combustion carbon stock in the furnace can reach 400 to 1400 Kg;Condensate throttling is a type of heat storage source other than boilers and steam turbines,which has a large amount of heat storage.In theory,it has a good adjustment effect for long-term and wide range fluctuations in load,and will not have an impact on the combustion side and steam water side.