Combustion Characteristics At High Temperature Of The Ash Agglomerating Gasified Coal Char

There are large number of coal in our country but less oil. According to this fact, the development of coal energy based on coal gasification and chemical industry is the most effective technological approach to achieve the goal which requires high efficiency, environmental protection and economy. Ash agglomerating coal gasification technology has many advantages, such as the gasification furnace's structure is sample; it can adapt kinds of coals; the product doesn't contain tar. But the carbon content of the gasified coal char that produced from the pressurized fluidized bed gasifier is high and taken a lot with airflow, that make the total carbon utilization is not high enough. The carbon utilization is enhanced by carbon combustion at high temperature, but the gasified coal char has the characteristics of low volatile, high ash, hard to combustion because it stayed a long time in the gasifier. So the research on the combustion characteristic at high temperature and the combustion reaction mechanism of gasified coal char can enhance the total carbon utilization, improve cascade use of resource and environmental friendly.The combustion characters and pore structure development of the gasified coal char obtained from the secondary cyclone of the Jincheng industrial gasifier was experimental studied at high temperature in a simulator of high-temperature entrained flow reactor. Gasified Chars were burned at the temperature of 1273K and 1573K, the oxygen contain of 5% and 20% and sampled along the reactor at different axial residence time. Pore structure and crystallite structure were analysised.Automatic adsorption instrument (ASAP 2020) were employed to measure absorption isotherms of sampled chars. Cryogenic nitrogen absorption isotherms, parameters such as BET specific surface area, BJH pore volume and average pore diameter were measured and analysised. Pore structure of the char was further researched by fractal theory and Scanning Electron Microscopy (SEM). The isotherms of char samples at different residence time were all typeⅡ. Higher temperature and much oxygen concern both can improve the development of char pore structure. The development of specific surface area during the combustion is the same as the trend of reacting rates of char. The char reacting rates in finial reacting period was mainly determined by char reactivity. The crystallite structural analysis was carried out by using Raman spectroscopy and X-ray diffraction (XRD). The change role of integral area radio of G band (1590cm-1), D1 band (1360cm-1), D3 band (1500-1550cm-1) of Raman spectroscopy was analysised. And the influence that crystallite structural made to reactivity was also analysised. The decomposition of organic matrix and the change role of aromatic rings during the process of gasified coal char combustion were analysised by X ray.Combustion kinetics of gasified coal char and fast pyrolysis coal char were calculated by a char combustion model. The diffusion resistance and oxygen pressure of char during combustion process were considered. And effective factor was used to mean the radio between observed rate parameter and chemical rate parameter. The active energy of gasified coal char calculated by chemical rate parameter is 90.9 KJ/mol. The chemical rate parameter calculated by DTF fits well with the one calculated by TG. As a result, the reactivity at high temperature can be reckoned on some degrees by the reactivity of coal char at low temperature.