Pyrolysis Using Solid Heat Carrier Of Lignite And Characteristics Of Semicoke

The development and utilization of quality thermal coal resource in China is in the relative transition,while the lignite resources is relatively abundant.Therefore, it has practical and economic significance to achieve the efficient and clean development and utilization of lignite which can relieve the tense situation of quality thermal coal resources.Considered with the characteristics of lignite of high volatile, high water content and low ignition and so on, the technology of solid heat carrier polygeneration pyrolysis which is designed to realize the comprehensive utilization of lignite through grading and transforming is the most effective way of the clean and efficient utilization. However, the process has many problems including the low production rate of the tar,the large amount of heavy tar and the unreasonable utilization of coke breeze.In order to improve the tar production rate and quality and to remain the gasification characteristics of semi-coke,which can improve the efficiency and completeness of the whole process. Relying on the sub-project of the national 863 program major projects of the research and development of catalytic heat carrier, this paper studies the effect of catalytic modulation of solid heat carrier to the production distribution and carbocoal characteristics which provide theoretical basis for the development of subsequent catalytic heat carrier.Pyrolysis temperature have the greatest impact on the structure of lignite semi-coke, In the investigation temperature of 400～600, the increase of pyrolysis temperature promote the small aromatic ring to large aromatic ring structure in semi-coal, the formation of no kind of graphite structure crystallite size increase, specific surface area increase, gasification reactivity decrease, the increase of pyrolysis rate were favorable for the formation of tar and a known structure.Internal minerals and the catalytic components such as Fe,Ca and Mg in olivine has also influence on the product distribution and composition from pyrolysis of lignite, and different effects on the featue of semicoke. Specific conclusions are as follows:coal minerals and the catalytic components of olivine has same effect on the the catalytic cracking of tar, which reduces the tar production rate and the heavy components in tar; Internal minerals of lignite contributes to the pyrolysis process, which accumulate the carbon crystal layer thickness (La) and increases the condensation degree of carbon, which is not conducive to the gasification reaction of the semi coke. Because the catalytic has greater effect than the microcrystalline structure on the gasification reaction of the semi coke, therefore, compared with the acid-washed semicoke, general gasification reactivity increases significantly. There is no catalytic components migrating to in the char during the process of pyrolysis of lignite,then, the olivine has less influence on the carbon crystal structure and condensation of carbon and its CO2 gasification reactionThermal process has a greater influence on the yield and composition of tar from the pyrolysis of lignite than olivine. Thermal process also effects the structure characteristic and reactivity greatly, there is two times larger in superficial area, and larger aromatic ring structure and CO2 gasification reactivity in the char from pyrolysis in self-heating of lignite than that from pyrolysis in external-heating.