Abstract The perchloroethylene coal cleaning process uses perchloroethylene as the solvent to remove both organic and inorganic forms of sulfur without any significant loss to its calorific value. The process removes these forms of sulfur in two sequential unit steps. The objective of this investigation was to determine the exact sequence of operations in the Process. Hence, organosulfur was removed before and after depyriting and demineralizing the coal. The extent of total sulfur as well as organic sulfur removal were compared in both cases. It was found that the desulfurization is more efficient when organosulfur is extracted before pyritic sulfur and not vice versa, in the sequential removal of organic and inorganic forms of sulfur. The data presented in this paper reestablishes a fact that the mineral matter content in coal is quintessential to its organosulfur extractability.
This study is designed to examine the effect of the CRA on the financial performance of 60 banks. For this sample of banks, performance measures such as return on assets (ROA), return on equity (ROE), salary expense ratios improve significantly in the five year period after the passage of the CRA. Furthermore, smaller banks benefitted more than bigger banks. An important implication is that banks may be able to improve their performance by penetration of lending markets in disadvantaged neighborhoods, as required by the CRA.
A mini-pilot plant has been designed and fabricated to study the removal of sulfur from coal using perchloroethylene in a continuous process. Perchloroethylene solvent is used in a recycle process stream to perform both physical and chemical cleaning of finely crushed coal. Organic sulfur is removed in an extraction stage using perchloroethylene at atmospheric pressure. Physical removal of pyrites and minerals takes place in a float/sink apparatus in which perchloroethylene is used as a heavy medium. The plant is used to study process efficiency, control, and to provide scale-up data. The process variables studied will include type of coal, solvent-to-coal ratio, and extraction time among others. Design of the plant using bench-scale data will be discussed. Unit operations will be discussed, including extraction, heavy medium separation, screen separation, and drying.
Perchloroethylene solvent can be used for both the physical and chemical cleaning of high sulfur, finely crushed coals. Previous studies using bench-scale extractions have shown that perchloroethylene solvent can remove from 20% to 60% of the organic sulfur in many coals. Associated research using glass tube settlers has demonstrated the potential for using perchloroethylene as a heavy medium for the removal of pyrites and mineral matter using a float/sink process. Additionally, a mini-plot plant has been designed and fabricated to study the cleaning of coal using perchloroethylene in a continuous process. Data from the studies are used to develop models for the unit operations in the coal cleaning process. The models are then used to support the design of a 36 MT/day pilot plant planned for future construction. Studies are done using ASPEN to assess the optimal configuration for the 36 MT/day pilot plant unit operations and to evaluate overall plant efficiency.
