| Coal gasification technology is an important mean of coal efficient utilization, which has been extensive attention-getting all around the world. A large number of experts and scholars made a depth study and research. However, among so many researches on coal pyrolysis and gasification reaction, most of them focused on pulverized coal, and the large size of coal were rarely involved. The relevant theoretical research is also lacking. In this paper, a new controlled atmosphere TGA furnace was used under atmospheric conditions, different size coal pyrolysis and gasification characteristics, which provides a strong theoretical basis for Underground Coal Gasification industry.In this paper, pyrolysis characteristics of a brown coal at atmospheric pressure, and factors such as pyrolysis temperature, heating rate, particle size were studied. Three size scale of coal samples corresponding to mass of 5mg, 10g and 20g were selected for coal pyrolysis experiment. According to the experiment, the pyrolysis TG curves of thermal decomposition of coal properties were analyzed. A high-temperature tube furnace and portable gas chromatograph was used to analyze the gaseous products such as H2, CO, CO2 and CH4 during pyrolysis, as well as the heating rate and pyrolysis temperature on the emission characteristics were studied. Moreover, this paper studied the mechanism of coal gasification under carbon dioxide atmosphere and coal char gasification reactivity was also investigated. From the experiment, the results show that on the initial stage of pyrolysis reaction, the larger size coal dehydrated more quickly and there is more coal gas releasing. Study found that at a lower heating rate the releasing amount of H2 increased while CO and CO2 are on the opposite.In this paper, characteristics of pyrolysis and gasification of brown coal were suited which provided data support and theoretical basis for Underground Coal Gasification and is conducive to the further development.
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