Experimental Study On Desulfuration Based On The Ultra-high Temperature Fume Producing Process

With the development of economic and society, there exists a urgent need of ultra-high temperature fume producing process in the steel, cement, metallurgy and other industries. However, the process with coal as its main fuel would produce large amounts of polluting gases which would damage the environment, and the critical reason is sulfur in coal. In this paper, the fundamental and technological research of desulfurization mechanism of the ultra-high temperature fume producing process was studied. The migration and removal characteristics of sulfur during the process was analyzed in-depth, which provided theoretical basis and empirical parameters to the actual production.In this study, Sichuan coal(SC), Shanxi coal(SX), Huangling coal(HL) and Linnancang coal(LN)were used. The pyrolysis experiment under nitrogen atmosphere and gasification experiment under nitrogen/steam atmosphere were determined in a fixed bed bench at atmospheric pressure. The migration characterisics of different forms of sulfur and the distribution of sulfur in different products druing pyrolysis and gasification were studied. Most inorganic sulfur in coal decomposes during pyrolysis and gasification, but only part of them release.The decompositon fo pyrite and the sulfur fixation of alkaline earth metals in coal could generate inorganic sulfide sulfur which remains in semi-coke.The increasing of temperature and the decreasing of the steam content both have a negative influence on the releasing of inorganic sulfide sulfur. There is a big link between the removal of organic sulfur in coal and the coal properties. High content of steam could inhibit the sulfur fixation of active organic matter effectively, which is propitious to remove the organic sulfur in coal. H2S is the main sulfurous gas during pyrolysis and gasification, and the amount of it is impacted by the sulfur content of raw coal, the steam content, the coal rank, the alkaline earth metal content and so on. The distribution of sulfur in products druing pyrolysis and gasification is as follows: most in coke, followed by gas, tar least. The increasing of steam content is in favor of transforming the sulfur from coke to gas.Sichuan coal was chosed to take gasification experiment under air/steam and combustion experiment of the mixture of semi-coke and ash in a fluidized bed bench at atmospheric pressure. The impacts of some factors, such as Ca/S ratio, steam content, kind of limestone and so on, on the desulfurization were studied. The releasing characteristics of sulfur in coal during gasification and combustion is related with the steam content. The higher the steam content is, the more sulfur would release during the gasification, but generally speaking, most sulfur releases during combustion. The increasing of Ca/S ratio is in favor of increasing the desulfurization efficiency. The impacts of different kinds of limestone to the desulfurization are different. The increasing of steam content isn't in favor of increasing the desulfurization efficiency and the use ratio of limestone.Finally, combined with the experiment results, some advises about desulfurization of the ultra-high temperature fume producing process were proposed: the desulfurization of combustion is important. Using uncalcined limestone as the desulphurization agent is not ideal, both the desulphurization efficiency and sorbent utilization was low, primarily due to not remove SO2 effectively druing combustion. In order to improve the desulfurization in ultra-high temperature fume producing process, it's necessary to add desulfurization agent in the combustion part, and another way is to calcine the desulfurization agent in advance.