Subbituminous coals analysis

Analysis. Analyses of a number of lignitic coals are given in Table 3. Figure 1, a distribution plot of 300 U.S. coals according to ASTM classification by rank, indicates the broad range of fixed carbon values (18). According to the ASTM classification, fixed carbon for both lignite and subbituminous coals has an upper limit of 69%, but in practice this value rarely exceeds 61%. 

For each coal, at the maximum in hydrogen content, or H/C atomic ratio, the aliphatic hydrogen content (determined by H NMR analysis) accounted for over 90% of the total hydrogen. The aliphatic hydrogen contents were 10.5% for the subbituminous coal,PSOC-1403, and 6.9% for the bituminous coal, PSOC-1266. The high aliphatic hydrogen content was associated with the presence of polymethylene chains. The early release of paraffinic material, as n-alkanes and as long chain substituents to aromatic structures, under conditions of mild pyrolysis has been observed in other research (13-15. ... 

The plant processes 26,840 TPSD of low sulfur North Dakota lignite. The sulfur is 1.3 wt%/DAF coal. The coal analysis is shown in Table II. Output from the plant is 268,700 MM Btu/day of SNG, equivalent to 45,000 BOE/day. Total production of by-product elemental sulfur is 161 tons/day. This represents 78 wt% of total sulfur input from the coal feedstock. Since goal gasification and indirect liquefaction facilities are most likely to use Western low sulfur lignite or subbituminous coals, this represents the low sulfur case for coal conversion. 

Figure 2 is the GPC of S02 solubles of SRC from subbituminous coal. As in the case of the sample in Figure 1, the GPC effluent was collected as four fractions. After SO2 extraction, the GPC areas of fraction 1 and 2 have decreased and the analysis of fraction 2 of the SC -solubles does not show the presence of any alkanes. Elemental analysis of fraction 2 following the evaporation of all the THF shows the following composition... 

RESULTS OF THE SENSITIVITY ANALYSIS FOR THE SUBBITUMINOUS COAL CORRELATION COEFFICIENT... 

Figure 13, Regression analysis to determine aromatic and aliphatic absorptivities. Key a, bituminous coals and products and b, lignite and subbituminous coals and...

Two coal processing modifications are being developed. In the first, coal gasification, subbituminous coal has been used. An analysis of a typical subbituminous coal is shown in Table I. 

The char from gasification of subbituminous coal is an ideal pulverized fuel A typical analysis is shown in Table IV for a char which has been devolatilized at 1600 F but has hot been partially burned to process heat, and for char which has been partially burned at 1900 F. 

EPRI Studies. In 1987, EPRI contracted with Fluor Daniel and Destec to conduct a detailed technical and economic analysis of IGCC power generation based on 400-MW plants for both Texas lignite and Wyoming subbituminous coal (9). Central and South West Services, Houston Lighting and Power, Texas Utilities Electric Company, and the Salt River Project also participated in this analysis. 

Reactivity of petroleum coke, like all solid fuels, is a function of chemical structure. Recognizing that the vast majority of all petroleum coke is produced in delayed cokers, analysis focuses upon delayed petroleum coke. Reactivity measures used here include maximum volatile yield and both devolatilization and char oxidation kinetics. Black Thunder Powder River Basin (PRB) subbituminous coal and Pittsburgh 8 bituminous coal are shown, for comparison, as reference fuels. 

Coals were devolatilized at rates comparable with those encountered in combustion and gasification processes. Rapid pyrolysis was attained with pulse-heating equipment developed for this purpose. This technique permitted control of the heating time and the final temperature of the coal samples. Subbituminous A to low volatile bituminous coals were studied. All bituminous coals exhibited devolatilization curves which were characteristically similar, but devolatilization curves of subbituminous A coal differed markedly. The products of devolatilization were gases, condensable material or tar, and residual char. Mass spectrometric analysis showed the gas to consist principally of H2, CHh, and CO. Higher hydrocarbons, up to C6, were present in small quantities. 

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