Experimental Study On The Gasification Characteristics Of Rapid-Pyrolysis Char Of Typical Coals

In the field of clean coal utilization technology, the technology of coal gasification not only occupies the most important position, but also has broad prospects for development and significance. The current high efficiency and large coal gasification technology is mainly based on the entrained flow gasification, the gasification condition is very rigorous, which involves the conditions of high temperature, high pressure and complicated multiphase flow. As the background of entrained flow gasification, the main research contents of this paper was as the in China’s five kinds of typical coals（including: bituminous, lignite and anthracite） as the research object, the rapid-pyrolysis char was produced in the high temperature drop tube which was similar to realistic gasification process. And the physical and chemical structure characteristics of coal and char will be discussed.The pore structure of five coals had obvious difference, lignite and bituminous coals contained abundant and, lignite is given priority to with macropores, bituminous coal to mesopores, and anthracite containing abundant micropores. The infrared spectrum shows that there is still a certain amount of containing oxygen functional groups and the oxygen structure in the rapid-pyrolysis char.The kinetic parameters of the gasification reaction of five kinds of rapid-pyrolysis char would be obtained by using the integral distribution activation energy method（DAEM）. This method could obtain the change curve of the activation energy and the conversion rate, which was helpful for us to understand the variation law of the reaction kinetic parameters in the whole gasification process. Curves showed that the initial stage of reaction activation energy changes was more influenced by residual volatile, and at the later stage of the reaction activation curve was more stable, indicating that the DAEM method application in a single reaction, could get more stable results. At the same time, the reaction rate and activ ation energy showed obvious kinetic compensation effect.In last part, respectively, we discussed CO₂ gasification reactivity of the chars by using the thermo gravimetry coupled with gas chromatography,and another using of high temperature deposition furnace. The former was discussed under different temperature of raw coal and coal chars with CO₂. The experiments showed that coal and char reactivity was different, but reaction laws of char was consistent with coal. At the same time, under the high temperature, some chars under the low temperature showed poor reactivity of coal char exhibited strong reactivity, which was due to some special carbon structures matter in coal char. The latter experiment discussed five kinds of rapid-pyrolysis chars at 1500 ℃ temperature and CO₂ gasification reaction characteristics of results under the high temperature drop tube. The results showed that, the effects of pore structure on the char gasification was the key, low rank coal, gasification characteristic of rich macropores and mesopores, and high rank coal although rich micropores, which promoted gas diffusion, however, was not conducive to the gas in the pore surface react. In general, the gasification reaction of gas diffusion and pore surface is interdependent, so rich micropores char showed a poor gasification reactivity.