Study On Gasification Characteristics Of Char From SD Coal Pyrolysis Based On Iron-based Oxygen Carrier

Coal gasification technology is the key technology of deep processing of coal to produce syngas,and the core content of clean and efficient utilization of coal.Therefore,vigorous development of coal gasification technology is the need of social development.Developing poly-generation technology based on coal pyrolysis and gasification is an effective means to realize comprehensive utilization of coal.Char,as a solid product of coal pyrolysis,has very important research value.Firstly,this paper takes SD coal pyrolysis char as the research object,and investigates the pyrolysis characteristics and gasification reaction characteristics of char.The study found that with the increase of the final temperature of pyrolysis,the weight loss of the char reduced,the weight loss rate increased,and the DTG curve moved to the high temperature region.When the char is pyrolyzed at a heating rate of 10°C/min,30°C/min,and 50°C/min,the weight loss of the char is between 15%and 16%,which is basically the same,but with the increase of the heating rate,the weight loss rate of the char decreased,and the DTG curve moves toward the high temperature zone.When the gasification temperature rises to final temperature at 30°C/min and 300°C/min,rapid heating gasification is helpful to the gasification reaction and improves the gasification activity of char.However,at high temperature,the reactivity of char decreases due to the influence of ash content in coal.According to the isothermal gasification reaction kinetics,the homogeneous model can more accurately describe the gasification reaction process.The reaction activation energies at slow temperature rise and rapid temperature gasification are 192.65 kJ/mol and 185.16 kJ/mol,respectively.The pre-exponential factor is reduced,and the rapid heating gasification is reduced by 7.49 kJ/mol compared to the slow heating gasification reaction activation energy.Secondly,iron-based oxygen carriers were prepared by precipitation method,and the effect of adding oxygen carriers in the process of mixed gasification of oxygen carriers and char was analyzed.It was found that both oxygen carrier and char reacted in nitrogen and carbon dioxide atmosphere.Oxygen carrier not only catalyzed the reaction,but also increased the reaction rate and provided oxygen medium for gasification process.The inert component Al₂O₃ provides support for the oxygen carrier and enhances the active area of the reaction.The reaction effect between the oxygen carrier Fe7Al3 and char is the best.The weight loss peak moves to the right with the decrease of the inert component Al₂O₃ content in the oxygen carrier.Due to the influence of the physical properties of the oxygen carrier,when the oxygen carrier and the char react at 900°C,the weight loss is the largest and the reaction effect is the best;Fixed bed experiments show that oxygen carriers are involved in the reaction in both nitrogen and carbon dioxide atmosphere.The gas products are mainly CO and CO₂.The CH₄produced during pyrolysis of char is consumed,and the CH₄ production cannot be detected.The reaction process is accompanied by the condensation process of char and a small amount of hydrogen is produced.