Effect of Liquefaction Processing Conditions on Combustion Characteristics of Solvent-Refined Coal

摘要

One of several direct liquefaction processes currently under advanced stages of development is the Solvent-Refined Coal-I (SRC-I) process. A major SRC-1 product option is a low sulfur, low ash solid (SRC) which could be used as an electric utility boiler fuel much in the same manner that pulverized coal is currently fired in this type of combustion equipment. SRC-I processing has been performed using three variations in the manner in which mineral matter and unconverted coal are separated from the hot coal liquid. These processes are the Pressure Filtration Deashing (PFD), Anti-Solvent Deashing (ASD), and Critical Solvent Deashing (CSD). Since processing conditions may influence the combustion of SRC-I solids produced, an experimental program was carried out at both the bench and pilot plant scale to determine the influence of processing (i.e. solids separation method) and combustion conditions on carbon burnout of these three varieties of SRC solid boiler fuels. Included in this study was an examination of NO/sub x/ emissions (particularly for the CSD SRC and PFD SRC) with the objective of attaining low NO/sub x/ emissions without adversely affecting combustion efficiency. The work was carried out at the laboratory, bench and pilot plant scales employing Thermo-Gravimetric analyses, Drop Tube Furnace testing, and Controlled Mixing History furnace testing, respectively. Reactivity and NO/sub x/ emissions results were compared with those obtained from two coals previously tested and used as reference coals. One of these coals was a high reactivity Wyoming subbituminous coal and the other was a low reactivity Kentucky high volatile bituminous coal. The type of processing scheme used in the SRC-I deashing step was found to have a major impact on the combustion properties of the resultant solid SRC product. (ERA citation 07:042080)