The Pyrolysis Of Coal And Sulfur Emission Characteristics Pilot Study

Petroleum and natural gas are absent in our country, but coal resources are very rich. Our country is the minority country, which takes coal as the primary energy sources in the world. Sulfur pollutant caused by coal combustion is the maximal and most serious atmosphere pollute source, bring great loss to our economy. So the control of sulfur pollutant is the emphasis of the curb of atmosphere contamination all alone in our country, moreover, the research of the rule of the sulfur release in coal combustion is one of the foundations of the coal clean combustion. Coal pyrolysis is the important preliminary phases of coal combustion, which is the primary evolution phase of sulfur contamination, so the knowledge of sulfur variance can not only let us know the sulfur presence forms and distribution, but also have important meaning to open up and evaluate new Desulfurization technology and coal conversion techniques.The pyrolysis characteristics and sulfur release characteristics during coal pyrolysis of three different coals, which include high volatile, were studied by TG-GC-MS(Thermal gravimetry-Gas Chromatography-Mass spectrum), tube furnace of pyrolysis reactor and intelligent fixup sulfur equipment. The two main sulfurous products, H₂S and COS, were detected and analyzed. According to these, effects of sulfur presence form, coal particle size and minerals to the different sulfur-containing gases release were obtained. At the same time, total sulfur release characteristics of Longkou coal flash pyrolysis were studied.First of all, Mettler-Toledo TGA/SDTA851^e analyzer was uesed to study the effects of experiment parameters to the pyrolysis characteristics. First, temperature is the main factor to influence the coal pyrolysis. With the rise of the temperature, coal pyrolysis will experience three stages, low temperature weight loss stage; alive decomposes stage and second release gas stage, thereinto alive decomposes stage is the main weight loss stage. Second, with the increase of the heating rate, the initiatory temperature of pyrolysis decreased but the final temperature increased, main pyrolysis temperature zone broaden, the max weight loss rate and pyrolysis peak temperature increased, total weight loss decreased, the activity energy E and exponential factor k₀ increased. Third, with the increase of the particles size, the curve of the TG moves to the hightemperature zone, the initiatory temperature of pyrolysis augment but the abeyant temperature decrease, the main pyrolysis temperature zone become narrower, the total weight loss decreased. Forth, with the coal rank goes higher, TG curves moves to the higher temperature zone, the initiatory temperature increased but the final temperature decreased, the main pyroylsis temperature zone become narrower, the max weight loss rate and pyrolysis peak temperature increased, the total weight loss decreased. The pyrolysis product release characteristic coefficient D minish, the volatilization capability decreased, E and ko increased.In the next place, tube furnace of pyrolysis reactor and intelligent fixup sulfur equipment was used to research the total sulfur release of Longkou coal by flash pyrolysisi. The data indicate that the main sulfur release temperature zone is between 450°C⁵00"Cand550°C⁶00°C , which are formed by unstable organic sulfur and pyrite separately. The rate of desulfuration changed no more after 600°C and the final desulfuration rate is around by 55%.In the end, Finnigan Trace DSQ GC/MS was used to explore the sulfur release characteristics by temperature-programmed pyrolysis (TPP). First, the main released sulfur-containing compounds are H2S and COS, the release curve of three coals are "single peak curve", the peak temperature is around 400 °C, the main release temperature zone is between 250°C⁶00°C. Second, temperature programmed pyrolysis compared with the flash pyrolysis, the release temperatures of organic sulfur and pyrite reduced about 100°C, this indicate that temperature has important influence to sulfur release. Third, with the augment of granularity, the quantity of H2S release decreased. Forth, minerals have great influence on the sulfur release during coal pyrolysis, alkaline minerals can react with H2S and fix it in char, acidity minerals can catalyze the decompose of C-S bond. At the same time, minerals can recede the output of COS.