We have several times documented the fact that some processes for the indirect conversion of Coal into liquid hydrocarbons - - wherein Coal is first gasified, with or without the addition of Steam, to generate a synthesis gas that is then passed over a catalyst and condensed into a blend of hydrocarbon liquids - - can lead to a buildup, or accumulation, of semi-solid wax on the catalyst surfaces.
We have also documented that the petroleum industry knows all about such "Fischer-Tropsch Wax", as it seems to be called in the trade, and has devised strategies for refining that Coal conversion byproduct into additional hydrocarbon liquids.
Some examples of such reportage would include:
USDOE Pays Mobil Oil to Refine CoalTL Wax | Research & Development | News; and,
Exxon Lubricating Oil from CoalTL Wax | Research & Development | News; which entries detailed,
respectively, United States Patent: 4684756, and United States Patent: 5290426 .
Those disclosed technologies reveal how Fischer-Tropsch wax, as can be deposited on catalysts during the chemical condensation of hydrocarbons from Coal synthesis gas, could be directly treated and refined, and further converted into substitute petroleum products.
Herein, via the initial link in this dispatch, we see a different productive approach to the matter:
Fischer-Tropsch Coal conversion by-product wax can simply be added to the raw Coal being fed into the gasifier, a procedure which seems to enhance the generation of hydrocarbon synthesis gas from the Coal.
The corporate originator of, and designated Assignee of the rights to, the technology is identified as "GTL Energy", of Colorado.
More properly, they should be listed as "GTL Energy (USA)", and are, in fact, the US subsidiary of the Australian firm, GTL Energy Limited, a privately held company headquartered in Adelaide.
The core focus of their business is, actually, the "upgrading" of lower-rank Coals; and they did, just last year, complete and commission a plant in North Dakota that processes high-ash, high-moisture lignite Coal into a cleaner solid fuel with higher energy content.
Herein, we see that they have developed a technology that, as noted, utilizes a by-product of indirect Coal liquefaction to enhance the total Coal conversion process, by improving the initial Coal gasification.
Comment follows excepts from:
"United States Patent 6,664,302 - Method of Forming a Feed for Coal Gasification
Date: December, 2003
Inventors: Robert French, et. al., Colorado
Assignee: GTL Energy, Colorado
Abstract: The invention provides a method by which low-rank coal may be processed to provide a high-energy feedstock for coal gasification and synthesis gas production. Preliminary coal, preparation, which may include washing and drying, is followed by wax-impregnation to produce a high-energy, low-moisture, stable feedstock. The wax is preferably obtained from an on-site Fischer-Tropsch reactor that also produces diesel fuel and naptha.
Claims: A method of producing a feedstock for coal gasification (which comprises) contacting coal with a Fischer-Tropsch wax at (specified conditions) to form a Fischer-Tropsch wax-impregnated coal;
(And) introducing said Fischer-Tropsch wax-impregnated coal to a coal gasification operation.
(And) wherein said coal has a Btu content of less than about 7,000 Btu/lb.
(And) wherein said Fischer-Tropsch wax-impregnated coal is mixed with water to form a slurry feedstock for coal gasification."
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Our excerpts don't do justice to GTL's sophisticated scheme, which also includes means for generating electricity from a portion of the Coal synthesis gas, both to supply the grid at times of peak demand and to provide the energy needed by the Coal gasification and conversion process itself.
In basis, though, it is a technology that enables the use of a Coal conversion by-product, obtained from "an on-site Fischer-Tropsch reactor that ... produces diesel fuel" from Coal syngas, to enhance and improve the production of feed gas for that "Fischer-Tropsch reactor" from that, relatively lower-rank, Coal.