Dakota researchers are conducting research on the liquefaction behavior of low-rank coals necessary to apply major developing processes to these distinctly different coals. In a 5-lb coal/h continuous process unit, synthesis gas, raw lignite, and anthracene oil solvent were reacted at elevated temperatures in single pass tests in a continuous-stirred tank reactor (CSTR). Product yield fractions were correlated with percent coal in the feed slurry, hydrogen donor (tetralin) concentration, and temperature. The molecular weight of the soluble but nondistillable yield fraction was markedly reduced by increasing
A number of operational difficulties occurred during the run with temperature control of the reactor being the first. This resulted from faulty thermocouple splices and cross connections of heater and power supplies during rewiring of the reactor. The remaining problems were of a more routine nature, but they required considerable attention during the run and interrupted two yield periods. The deashing unit was operated early in the run and of the two yield periods completed, one was made after the deashing unit was shut down. Material balance closures were 100.3 percent and 101.8 percent for yield periods M-34A and M-34D, respectively. Adjustment of the material balance to 100 percent for each of the yield periods is discussed in the detailed write-up of the run (see Appendix A). Net gas yields averaged 35.2 weight percent while the net organic liquid yield was 66.3 percent of the MAF lignite fed. These values vary only slightly from those of Run M-33. Overall conversion was 91 percent compared with 92 percent of the MAF lignite fed in Run M-33. Averaging the results obtained for the six yield periods in both Runs M-33 and M-34 indicate that the net gas and net organic liquid yields when processing Gascoyne lignite are 36 and 64 weight percent of the MAF lignite charged, respectively, while the average overall conversion for the two runs was 91.5 percent. Comparing the ash and pyridine insolubles in the F-1 vacuum bottoms for yield period M-34D in which the deashing unit was not used with the sum of the pyridine insolubles and the ash in the SRL after deashing in Run M-34A showed that the product deashing was successful. In the former instance the insoluble material plus ash totaled nearly 27 percent of the vacuum bottoms while deashing reduced those materials to 0.6 weight percent of the final product. Only about 3 percent of the SRL charged was lost to the residue during the deashing process. Following Run M-34 approximately 85 pounds of oily solids and 23 pounds of solvent were removed from the reactor by blowdown. Samples of the solid material were analyzed for pyridine insolubles both before and after extraction with toluene. Additionally, sieve analysis showed 29 percent of the reactor solids larger than 21 microns and nearly 72 percent larger than 15 microns. This reflects an increase in particle size compared with the feed material and may indicate growth of .particles of minerals such as calcium carbonate.. Dried reactor solids were analyzed by X-Ray diffraction and by X-Ray fluorescence. The former analysis showed calcite to be the most abundant mineral with quartz, anhydrite and feldspar showing decreasing abundance.-11-3. Run M-35 Run M-35 was another in the series of runs to evaluate the effects of lignite variation on PDU operability and liquefaction yields. Lignite mined by the Consolidation Coal Company near Velva, North Dakota was used in this run. Velva lignite is similar in chemical makeup to Zap lignite even though slight variations exist in the chemical composition of the two ashes. Nominal ...
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