Distribution of sulfur during coal pyrolysis in a high pressure entrained-flow reactor

Desulfurization of coal prior to combustion can be achieved by one or more of the following methods. (1) Advanced physical cleaning--this method involves a variety of approaches for reduction of pyrite in the coal based on the differences between the density of pyrite or marcasite and the organic matrix. (2) Chemical coal cleaning--based on the concept of breaking the chemical bonds of the organic sulfur by exposing the coal usually to molten chemicals such as sodium hydroxide. (3) Conversion of the coal to low-sulfur liquid and gaseous fuels--based on liquefaction and gasification technologies. According to the literature, there are three commonly recognizable forms of sulfur in coal: sulfate, pyrite and organic sulfur. Although the distribution of various forms of sulfur is less often determined than the total sulfur, their presence can have a significant effect on coal utilization. However, the degree to which the sulfur can be reduced and/or removed from the coal is strongly dependent on the forms of sulfur present in the coal. Therefore, accurate analytical data on the forms of sulfur is a requirement for improving removal processes. Pyrolysis has been used by some researchers to study the behavior and distribution of sulfur in coal. Some investigatorsmore » have also used pyrolysis in order to study the chemistry and kinetics of reactions involving sulfur-containing compounds in coal. The purpose of the current work was to determine the distribution of the total sulfur between the products of pyrolysis (tars and chars) and the various forms of sulfur in the chars from pyrolysis of a subbituminous coal in a high pressure entrained-flow reactor.« less