Upgrading of Zhaotong coal by pyrolysis and its effect on the gasification reactivity

In order to integratedly utilize the relatively rich coal resource of Zhaotong mine, temperature-programmed pyrolysis experiments of Zhaotong lignite were performed in fixed bed reactor at different temperatures. The resultant coal tar and char were characterized by GC-MS and Raman Spectroscopy, respectively. Char-H₂O isothermal gasification characteristics were evaluated in fixed bed reactor at 850℃. The results show that in pyrolysis at 700℃ the cumulative content of H₂, CO and CH₄ in gases accounts for about 70%, and the growth rate of low calorific value of gas is the fastest, which is 90% based on the value at 500℃. A large number of phenolic compounds are generated at 500-700℃. Above 700℃ the decomposition reactions of the phenolic compounds is intensified. With the increase of pyrolysis temperatures, the apparent reaction rate of char decreases, while the molar ratio of CO₂ and CO increases. The molar ratio of H₂ and CO in gasification from char pyrolyzed at 700℃ was the highest.