Moisture, ash-free basis

The standard method for the ultimate analysis of coal and coke (ASTM D-3176) includes the determination of elemental carbon, hydrogen, sulfur, and nitrogen, together with the ash in the material as a whole. Oxygen is usually calculated by difference. The test methods recommended for elemental analysis include the determination of carbon and hydrogen (ASTM D-3178), nitrogen (ASTM D-3179), and sulfur (ASTM D-3177 ISO 334 ISO 351), with associated determination of moisture (ASTM D-3173) and ash (ASTM D-3174) to convert the data to a moisture-ash-free basis. 

All experiments in dilute-phase hydrogasification used a feed of Pittsburgh seam coal having a free-swelling index of 8 and a volatile content of 41% moisture- ash-free basis. Ultimate and proximate analyses... 

The Whatman No. 1 paper (as received) contained 4.1 vol Z moisture and 0.074 wt Z ash. All results reported here are on a moisture- ash-free basis unless other wise specified. Table II summarizes some analytical results of cellulose and condensed-phase cellulose pyrolysis products. A comparison of the results In Table II for cellulose and cellulose tars Indicates that the elemental composition of these two materials Is very similar. (The heating... 

Brown coals, like the hard coals, are also defined in terms of their calorific value (see the previous text) and were also recognized as potential fuels. The International System for the classification of brown coals is based on two inherent characteristics which indicate the value of brown coals as fuels (1) the total moisture (ash-free basis) and (2) the yield of tar (daf basis). Thus, the six classes of brown coal based on the ash-free, equilibrium moisture content are divided into groups according to the yield of tar on a dry, ash-free basis (Table 2.14). This system indicates... 

Coal analyses are reported on severalbases, and it is customaiy to select the basis best suited to the application. The as-received basis represents the weight percentage of each constituent in the sample as received in the laboratoiy. The sample itself may be coal as fired, as mined, or as prepared for a particular use. The moisture-free (diy) basis is generally the most useful basis because performance calculations can be easily corrected for the ac tual moisture content at the point of use. The dry, ash-free basis is frequently used to approximate... 

Total Carbon. The total carbon in Seam 4 varied between 62.09 and 74.18%, while in Seam 2 it varied between 62.27 and 67.80%. The total carbon presented in Table I is not on an ash-free basis, but on a moisture-free basis. The total carbon does not vary widely in either of the seams. However, it appears to vary more in Seam 4 than in Seam 2. 

Analyses reported on a dry basis are calculated on the basis that there is no moisture associated with the sample. The moisture value (ASTM D-3173 ISO 331 ISO 589 ISO 1015 ISO 1018 ISO 11722) is used for converting as determined data to the dry basis. Analytical data that are reported on a dry, ash-free basis are calculated on the assumption that there is no moisture or mineral matter associated with the sample. The values obtained for moisture determination (ASTM D-3173 ISO 589) and ash determination (ASTM D-3174) are used for the conversion. Finally, data calculated on an equilibrium moisture basis are calculated to the moisture level determined (ASTM D-1412) as the equilibrium (capacity) moisture. 

Moisture and ash (Chapter 3) are not determined as a part of the data presented for ultimate analysis but must be determined so that the analytical values obtained can be converted to comparable bases other than that of the analysis sample. In other words, analytical values may need to be converted to an as-received basis, a dry basis, or a dry, ash-free basis. When suitable corrections are made for any carbon, hydrogen, and sulfur derived from the inorganic material, and for conversion of ash to mineral matter, the ultimate analysis represents the elemental composition of the organic material in coal in terms of carbon, hydrogen, nitrogen, sulfur, and oxygen. 

Dry, ash-free basis data calculated to a theoretical base of no moisture or ash associated with the sample (ASTM D-3173 ASTM D-3174). 

Empirical parameter describing how the Donnan volume varies with ionic strength. Carboxyl group content (mmolg 1 on moisture- and ash-free basis). 

All data are reported on a moisture and ash-free basis. b The value of s is one standard deviation for four determinations. 

The ash content of raw and treated coals is reported on a moisture-free basis and the sulfur content on both a moisture- and ash-free basis. The ash reduction achieved corresponds to the overall change in moisture-free ash content divided by the moisture-free ash content of the raw coal. The reduction in total sulfur content corresponds to the change in total sulfur content divided by the total sulfur content of the raw coal, all on a moisture- and ash-free basis. The apparent reduction in organic sulfur content corresponds to the difference between the sulfur content of the acid-leached raw coal and the final sulfur content of the acid-leached, alkali-treated coal divided by the sulfur content of the acid-leached raw coal, all on a moisture- and ash-free basis. Coal recovery corresponds to the mass ratio of coal recovered during the alkaline treatment step to coal charged, all on a moisture- and ash-free basis. 

Several bituninous coals have been treated with molten mixtures of NaOH plus KOH at 350-370 C in a 1 10 coal-to-caustic ratio for 1 hour and then washed with water, dilute acid, and finally with water again. By this procedure, which is similar to that of the TRW Gravi-melt Process, 80-90% of the ash and 70-80% of the total sulfur have been removed with a recovery of 80-90% of the coal on a moisture- and ash-free basis. The desulfurization could be improved by using a finer grind of coal, better washing procedures, or a recleaning step. 

Coal treated at the Ames Laboratory with molten caustic by a procedure similar to that of the Gravimelt Process resulted generally in 80-90% reductions in ash and 70-80% reductions in total sulfur. The recoveries of coal on a moisture- and ash-free basis were 80-90%. 

Analytical results (Table 1) show that SRC have very high volatile matter and nitrogen contents (52-60% and 1.8-1.9%, respectively, on a dry-ash-free basis) and very low moisture and ash contents (0.1-0.3%, as-received basis in each case). The Higher Heating Values for the SRC (15,920-16,115 Btu/lb, dry-ash-free basis) are much higher than those of reference coals (13,290 and 14,110 Btu/lb for the WSB and KHB coals, respectively). 

The mg of galacturonic acid obtained in this way is the content of one-tenth of the weight of the washed and dried sample. To calculate the percent galacturonic acid on a moisture-and ash-free basis, multiply the number of mg obtained by 1000/x, in which x is the weight, in mg, of the washed and dried sample. If the pectin is known to be of the nonamidated type, only V and Vi need to be determined, and V3 may be regarded as zero in the formula for calculating mg of galacturonic acid. 

When Monarch (Lower Bench) coal (W-74-53) was hydrotreated with synthesis gas In anthracene oil and 25 wt% moisture at 425 + 5°C, an operating pressure of 3900-4000 psl, and a reaction time of one hour, a 99% conversion and 727. selectivity to oil on a moisture- and ash-free basis was observed. The viscosity of the coal oil in anthracene solvent was remarkably low, 53 cen-tlpolses at 60°C. At lower residence time from 15 min. to 30 min., the product oil resulted In a high viscosity, even-though the conversions were not greatly affected. These data are shown in Table III and Figure 1. 

Essentially all the subbltumlnous coals when hydrogreated with synthesis gas In anthracene oil and adequate amounts of moisture resulted In high conversions varying from 90 to 99% on moisture- and ash-free basis at a temperature of 425 + 5°C, an operating pressure of 3500 to 4500 pslg, and a residence time of an hour. The product oil Invariably had a low viscosity. 

Elemental analysis (in percent on a moisture-free and ash-free basis). 

Reliability Run 932-2A, which was made with fly ash, discharged a sludge containing 61 percent solids, and required a makeup of 17.5 lb/ton S02 When these data are normalized to a fly-ash-free basis, at equal limestone utilization, and equal sludge moisture, they yield the same makeup rate of 10.7 lb/ton SO2 for a concentration of 1500 ppm adipic acid in the scrubbing liquor. 

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