We have many times documented that Coal can be gasified, reacted, with varying amounts of both Carbon Dioxide and Steam, in order to form a hydrocarbon synthesis gas of variable composition, a composition which can be "tailored", so to speak, by adjusting the ratios of Coal, CO2 and Steam in the mix of reactants, so as to make the resulting synthesis gas suitable in composition for catalytic condensation into a specifiable range of liquid and/or gaseous hydrocarbon products.
A particularly interesting, from our point of view, example of our prior reportage on that issue would be:
California Hydrogenates Coal, & CO2, with Steam | Research & Development; wherein we discussed:
"United States Patent 4,162,959 - Production of Hydrogenated Hydrocarbons; 1979; Assignee: Occidental Petroleum Corporation, Los Angeles; Abstract: In a continuous process for recovery of values from a solid carbonaceous material, the carbonaceous material is pyrolyzed in the presence of a particulate source of heat to yield a particulate carbon containing residue of pyrolysis and volatilized hydrocarbons while simultaneously the volatilized hydrocarbons are hydrogenated. Steam and/or carbon dioxide can be introduced into the pyrolysis reaction zone to interact with carbon containing residue contained therein."
Occidental's technology, in fact, describes a process wherein Coal is first gasified, "partially oxidized", in what most descriptions of such technology label as a "traditional" manner, with only air or Oxygen, to generate what we would characterize as a "first cut" of hydrocarbon synthesis gas. The still-carbonaceous residues from that initial gasification are then reacted, further gasified, with Steam and/or Carbon Dioxide, depending on the product gas composition desired, and, the resultant product synthesis gas can then be blended with the first, partial oxidation, syngas, so as to tailor a final product suited in composition for catalytic conversion into a specifiable range of liquid and gaseous hydrocarbons.
And, we note that, in Occidental's technology, the initial partial oxidation of the Coal provides the heat to make the Steam which hydro-gasifies those carbonaceous gasification residues, with or without the addition of Carbon Dioxide.
As sophisticated as Occidental's technology might seem, herein, from Shell Oil, we submit description of even further, and very recent, refinements of such technique, wherein Steam and Carbon Dioxide can both be utilized in the gasification of Coal, so that the entire Carbon content of the Coal and of the Carbon Dioxide is consumed in the production of synthesis gas suitable for catalytic condensation into hydrocarbons.
We note, in advance, that Shell's technology herein seems to specify the use mostly of Carbon Dioxide that might become available within the process itself; and, we are uncertain in this case what the potentials for importing CO2, from extraneous sources, as seems to be the case in the above-cited Occidental Petroleum US Patent 4,162,959, into the system might actually be.
However, Shell Oil's process herein does, if nothing else, describe a technology wherein the entire Carbon content of the Coal is converted into Hydrocarbon Synthesis gas, and, that conversion is accomplished without the release of any Carbon Dioxide into the environment, with the attendant wastage of some the carbon content in the Coal such CO2 release would imply; and, it is accomplished without the need to import any energy from external sources into the process.
Comment follows excerpts from the initial link in this dispatch to:
"United States Patent 7,829,601 - Partial Oxidation Process of a Solid Carbonaceous Feed
Date: November, 2010
Inventors: Johannes Ploeg, et. al., Netherlands
Assignee: Shell Oil Company, Texas
Abstract: The invention is directed to a process for preparing a mixture comprising CO and H2 by operating a partial oxidation process of a solid carbonaceous feed, which process comprises the steps of:
(Supplying) the solid carbonaceous feed and an oxygen-containing stream to a burner, wherein a CO2 containing transport gas is used to transport the solid carbonaceous feed to the burner;
(Note that both Coal, the semi-anonymous "carbonaceous feed" and Carbon Dioxide are to be reacted in the initial gasification, with an "oxygen-containing stream". We have documented many times, as, for instance, in: More Oklahoma CO2 + Coal = Hydrocarbon Syngas | Research & Development | News; wherein is detailed: "US Patent 4.040,976 - Process of Treating Carbonaceous Material with Carbon Dioxide; 1977; Assignee: Cities Service Company, OK; Abstract: A mixture of carbon dioxide and a carbonaceous material, such as coal, is rapidly heated in a reactor, giving a gaseous effluent comprising carbon monoxide"; that: Carbon Dioxide and hot Coal can be reacted together, with both being consumed in the generation of useful and reactive Carbon Monoxide.)
(And) partially oxidizing the carbonaceous feed in the burner wherein a gaseous stream comprising CO and H2 is being discharged from said burner into a reaction zone, wherein the temperature in the reaction zone is from 1200 to 1800C and wherein said reaction zone is at least partly bounded by a wall, which wall comprises conduits in which steam is prepared by evaporation of water, resulting in a flow of steam being discharged from said reaction zone;
(Note, again: Heat generated by the initial Coal gasification is utilized to generate the Steam.)
(And) monitoring the conditions in the reaction zone by continually or periodically measuring the rate of the steam flow and using said flow rate as input to adjust the oxygen-to-coal (O/C) ratio.
(And) wherein the solid carbonaceous feed is coal.
A process ... wherein (the monitoring) is performed by a computerized system, which system compares the steam flow rate as measured with an optimal steam production valid for the actual synthesis gas production (so that adjustments in feed ratios can be made to effect) the optimal production of CO and H2.
A process ... wherein the CO2 poor stream as obtained in step (e) is further purified and subjected to a methanol synthesis reaction to obtain methanol; to a dimethyl ether synthesis reaction to obtain dimethyl ether; or to a Fischer-Tropsch reaction to obtain various hydrocabons.
Field and Background: The present invention is directed to a process for operating a partial oxidation process of a solid carbonaceous feed to prepare a mixture comprising of CO and H2. Mixtures of CO and H2 are also referred to as synthesis gas.
Process control is important in a process wherein solid carbonaceous feeds are partially oxidized. It has been found that the quality of the synthesis gas as obtained may vary, due to e.g. disturbances or variations in the solid carbonaceous stream and the oxygen containing stream being fed to the gasification reactor, the amount of ash in the carbonaceous stream, etc. If for example coal is used as the carbonaceous stream, variations in H2O content of the coal may result in altered process conditions in the gasification reactor, as a result of which the composition of the synthesis gas will also vary.
Summary: In some embodiments the invention provides a process for preparing a mixture comprising CO and H2 by operating a partial oxidation process of a solid carbonaceous feed (which includes) supplying the solid carbonaceous feed and an oxygen-containing stream to a burner (and) wherein a CO2 containing transport gas is used to transport the solid carbonaceous feed to the burner ... ."
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The upshot of the whole thing, as we read it, is that Coal can be converted, through reactions with variable amounts of Steam and Carbon Dioxide, at least some of which CO2 is generated within the system, in a process which can be monitored and adjusted so as to arrange for the compounding of, as desired, a hydrocarbon synthesis gas suitable for catalytic condensation into either Methanol; or, the substitute Diesel fuel, Dimethyl Ether; or, via the "Fischer-Tropsch reaction", other and "various hydrocabons".
And, all of that is accomplished with no CO2 being, as we read it, emitted to the environment; and, without the need for any separate, external source of energy.
The only things really needed, to cleanly and efficiently make "various hydrocarbons", are Oxygen, Water and Coal.