Experimental Study on Sulfur Removal from Pyrolysis Coke by Organic Acid

Abstract

During raw coal pyrolysis for preparing clean coal, FeS2is mainly converted to FeS, which is the main source of SO2 emission in clean coal combustion. This research proposed a method using organic acid for sulfur removal from pyrolysis coke. In terms of the dissolution tests of FeS (analytical reagent), several organic acids were chosen to study the effects of different organic acids (oxalic acid, citric acid, acetic acid), applied concentrations (0.1 mol/L-1 mol/L) and coal ranks (anthracite, bituminous coal) on sulfur removal process. Results show that FeS dissolves more in oxalic acid, citric acid and acetic acid compared to other organic acids. The amount of FeS dissolved in each of the three acids is about 1/3 of that in hydrochloric acid. Coal pyrolysis was conducted in a tubular furnace to make coke with volatile matter released, in which FeS2was converted to FeS. Sulfur content in the coke was measured by a Coulomb sulfur analyzer according to GB/T 214-2007. 1 g coke was immersed into 25 mL acid solution for 8 h, washed by distilled water, and then dried to be measured by the analyzer. For high sulfur content anthracite pyrolysis coke and bituminous coal pyrolysis coke, oxalic acid has the highest sulfur removal rate, followed by citric acid and acetic acid. The removal rates for pyrolysis coke from high sulfur content anthracite and high sulfur content bituminous coal are 8.1% and 11.8%, respectively, by 0.25 mol/L oxalic acid. The rate has little change under a higher concentration of 0.5.