Study On The Pyrolysis Characteristics Of Coal-water Slurry And Coal-oil-water Slurry

Coal-water slurry and coal-oil-water slurry are new coal-based clean fuels,and the application of related technologies has the dual significance of environmental protection and energy efficiency.The pyrolysis of coal-water slurry and coal-oil-water slurry is the first step in the combustion and gasification reaction process,and they are the basis for the clean utilization of coal.Therefore,it is of great significance to study the pyrolysis of coal-water slurry and coal-oil-water slurry.Based on this,this paper used a high-temperature tube furnace to carry out pyrolysis experiments for coal-water slurry and coal-oil-water slurry under different conditions,and then carried out further research on the structure and combustion characteristics of coal char after pyrolysis;finally,this article used Lammps to pyrolyze the pyrrole and pyridine in N₂ and steam to explore the law of nitrogen migration and transformation.First of all,this paper conducted pyrolysis research on different concentrations of coal-water slurry and coal-oil-water slurry at different temperatures(800,900 and 1000?),and investigated the change law of the CO,CO₂,CH₄and H₂ with pyrolysis temperature and coal slurry concentration.The results show that under the condition that the concentration of coal-water slurry and coal-oil-water slurry remain unchanged,as the pyrolysis temperature increases,the production of CO,CH₄,CO₂,and H₂gradually increases.At the same temperature,as the water content of the coal-water slurry increases,the production of CO and CH₄ gradually decreases,while the production of CO₂ and H₂ gradually increases;as the oil content of the coal-oil-water slurry increases,the production of CO and CO₂ gradually decreases,while the production of CH₄ and H₂ gradually increases.Secondly,the above pyrolysis coke structure and the combustion reactivity of coal char were analyzed.As the pyrolysis temperature and the water content in the coal water slurry increase,the order of carbon crystallites of the coal water slurry pyrolysis coke gradually increases,which reduces the combustion reactivity.As the pyrolysis temperature increases and the oil content in the coal-oil-water slurry increases,the degree of ordering of the carbon microcrystals of the coal-oil-water slurry pyrolysis coke gradually increases,which reduces the combustion reactivity.Finally,the change law of nitrogen-containing pyrolysis gas was obtained by pyrolysis of different concentrations of coal-water slurry and oil-water coal slurry at different temperatures:with the increase of pyrolysis temperature and water content in the coal water slurry during the pyrolysis process,the relative contents of HCN and NH₃ gradually increase;with the increase of pyrolysis temperature and oil content in the coal-oil-water slurry during the pyrolysis process,the relative contents of HCN and NH₃ also gradually increase;and the relative content of pyrolyzed HCN of the two is much higher than the relative content of NH₃.In order to study the migration law of N during the pyrolysis process,the classical molecular dynamics software Lammps was used to pyrolyze pyrrole and pyridine under N₂ and water vapor atmosphere.The results show that the increase of temperature can promote the decomposition of pyrrole and pyridine to promote the formation of HCN and NH₃;during pyrolysis in the water vapor atmosphere,the water vapor will provide a large amount of H free radicals to promote the formation of HCN and NH₃.