Research On The Synergistic Mechanism And Optimization Of Coal Blending And Co-combustion With Tobacco Rods Under Oxygen-enriched Conditions

Biomass has negative carbon properties,and plays an important and irreplaceable role in promoting China’s carbon peak and carbon neutral goals.Oxygen-enriched combustion technology not only has high combustion efficiency,but also has the advantage of carbon capture.Carbon capture and carbon storage of biomass plus oxy-fuel combustion can achieve negative carbon emissions.Applying Yunnan’s rich coal resources and waste tobacco stem biomass resources in combination with oxy-fuel combustion in the fields of metallurgy,electric power and the chemical industry will not only improve the level of my country’s economic development,but also achieve the goal of carbon neutrality as soon as possible.Therefore,this paper uses methods and methods such as experimental analysis,theoretical calculation,numerical simulation,and the engineering application to study the synergistic mechanism and optimization of the oxygen-enriched mixed combustion of bituminous coal,lignite and tobacco stems.It can effectively promote the clean,low-carbon and efficient use of Yunnan’s local characteristic tobacco stem biomass resources and coal resources,as well as the early realization of the goal of carbon neutrality.In order to reveal the synergistic mechanism of oxygen-enriched mixing combustion of bituminous,lignite and tobacco stem,the optimum conditions of oxygen-enriched mixing combustion of bituminous,lignite and tobacco stem were studied.Based on the thermogravimetric experiment,the response surface optimization method was used to optimize the oxygen concentration,heating rate,coal blending and tobacco stem ratio,and the optimal conditions were rich source Bituminous:Xiaolongtan lignite:Yiliang tobacco stem mass ratio of 6:2:2.Under the optimal conditions of 30%oxygen concentration and 20K/min heating rate,the flammability index of the mixed fuel is 47.1892×10^-7,the combustion characteristic index is 4.9971×10^-10,and the burnout temperature is 478.2℃.The study about synergistic mechanism of oxygen-enriched cocombustion with bituminous,lignite and tobacco stem are carried out.The thermogravimetric experiment is carried out around the influence of factors such as the heating rate,the oxygen concentration,and tobacco stem ratio on the combustion characteristics of mixed fuel.The synergistic law of co-combustion of different ratios of tobacco stem and coal blends in an oxygen-enriched atmosphere was explored,and the study found that the synergistic temperature range of different mixing ratios was 200℃～750℃.By calculating the integral value of fuel interaction efficiency of different blending ratios,a synergy model of bituminous,lignite and tobacco stem oxygen-enriched mixed combustion was established,and the characteristic parameters of different blending ratios were obtained.The logistic model was used to establish the mixed fuel co-evolution equation,and the co-evolution mechanism of the co-combustion process was revealed.Aiming at the synergistic problem of water evaporation,volatile matter volatilization and carbon combustion reaction during the co-combustion of bituminous coal,lignite and tobacco stem,thermogravimetric experiment and Coats-Redfern method were used to study the synergistic kinetic mechanism of oxygen-enriched mixed combustion.Combustion kinetics parameters of three single fuels and mixed fuels with different ratios were obtained,and the synergistic models of activation energy for mixed combustion in stages I and II of combustion reaction be established.Finally,the synergistic model is validated,and it is found that the model predicted values deviate from the experimental values by less than±10%,and the calculation is high.Based on the explanation of the synergistic law of mixed fuel combustion in an oxygen-rich atmosphere and the synergistic mechanism of reaction kinetics,the flammability index,comprehensive combustion characteristic index,pre-reference factor and activation energy are used as evaluation indicators.The TOPSIS method was used to optimize the different ratios of bituminous,lignite and tobacco stem,and the optimal quality ratio of Fuyuan bituminous:Xiaolongtan lignite:Yiliang tobacco stem was 6:1:3.In order to enable basic theoretical research to better guide actual production,this thesis also carried out the following two aspects of work.On the one hand,based on the three fuels mixed the combustion test carried out by a 600MW boiler,a corresponding numerical simulation study was carried out.Research has obtained the distribution characteristics and laws of furnace temperature,flue gas composition,NO_xconcentration.At the same time,numerical simulation is verified by combining test data of some fields.On the other hand,the fouling characteristics of mixed fuels were experimentally studied.The properties of ash accumulation,such as ash content,ash melting point,sintering strength and surface morphology,were studied.