| Coal consists of microscopically recognizable organic materials so called macerals and less amount of mineral compounds chemically bound or dispersed in organic materials. Coal composition and properties depend upon the original plants from which coal is derived and the biochemical and physichemical changes that take place during coalification. Since the changes for different macerals can differ considerably from each other, each sort of coal macerals has its own special properties that influence the behavior and performance of coal during processing and utilization.In this paper, some inertinite-rich concentrates and vitrinite-rich concentrates derived from four low rank bituminous coals (YM, DT, PS and LT A-3) have been separated according to the density gradient centrifugation separation principle and comparison has been made for their reactivity with CO2 and kinetic parameters. To study the synergistic effects between different macerals during gasification, some samples derived from three low rank bituminous coals (SH, PS and HDG) with different content of inertinite and vitrinite have been separated using sink-float separation process by means of the solutions with different specific gravities varying from 1.25 to 1.60. A large amount of gasification tests have been done with the Thermogravimetric Analysis (TGA) method and a tube reactor, respectively. The specific reactive rate, the average specific reactive rate, the initial specific reactive rate and the reactivity index for gasification with CO2 of various char samples from the inertinite-rich concentrates and vitrinite-rich concentrates have been calculated based upon the test results.It was found that the conclusions may be different if different expressions are adopted. The reactivity with CO2 of coal macerals are correlated with reactive temperature and holding time. At relatively lower temperature, the difference of CO2-reactivitiy between inertinite-rich and vitrinite-rich concentrates is small. But at higher temperature, theCO2-reactivity is in the order: inertinite > vitrinite. The influence of temperature on CO2-reactivity of various macerals is different. At relative lower temperature, the CO2-reactivity of inertinite-rich concentrates increases more obviously than that of vitrinite-rich concentrates as temperature increases. But at higher temperature, the influence of temperature on CO2-reactivity of inertinite-rich concentrates decreases in comparison with vitrinite. The CO2-reactivity of both vitrinite-rich and inertinite-rich concentrates decrease with coal rank increasing, but the difference of CO2-reactivity between vitrinite and inertinite becomes smaller. The CO2-reactivity of char samples fromcoal macerals is related to specific surface area (SN2) measured with N2 adsorption method. The larger the SN2 is, the higher the CO2-reactivity is. The test data on CO2-reactivity ofcoal macerals are well expressed by Unreacted Shrinking Core Model in which chemical reaction is considered as the rate-controlling step. Either active energy or pre-exponential factor doesn't explain the difference of CO2-reactivity between vitrinite and inertinite, and kinetic compensation effect between active energy and pre-exponential factor was observed.It was also found that the synergistic effects between different coal macerals during gasification are significant. The higher the content of inertinite in coal samples, the higher the CO2-reactivity of gasification. The CO2-reactivity of char samples from coal macerals is quite low when the content of vitrinite in the certain range. The gasification extent of different maceral-rich concentrates is correlated with V/I, I/(V+E) and E/I, the regression equation is as follows:where GE is gasification extent, V, I, and E represent the content of vitrinite, inertinite and exinite, respectively and a0, a1, a2 and a3 are regression constant.
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