We recently made report, as now accessible on the West Virginia Coal Association's web site via:
Oklahoma Oxygen Donor Coal Gasification | Research & Development;
of an innovative Coal gasification technique, developed by Phillips Petroleum and as disclosed in the report through a series of three United States Patents awarded to Phillips, that uses an intermediary, Zinc Oxide, to accomplish both the controlled gasification of Coal, to produce, primarily, Carbon Monoxide, in a way which nearly eliminates the co-production of Carbon Dioxide, and, which, in the regeneration of the oxidant Zinc Oxide, produces Hydrogen, for combining with the Carbon Monoxide to form hydrocarbon synthesis gas, from Water.
There's a bit more on that integrated Phillips technology to follow in a future report, and we regret that we initially missed a bit or two of it; but, herein, we wanted to demonstrate that the concept of using an Oxygen donor substance, to effect the efficient conversion of Coal into reactive Carbon Monoxide, while preventing in large part the co-production of Carbon Dioxide, is a recognized concept within the petroleum industry.
And, there are substances aside from Zinc Oxide which can accomplish the task, that, while they might not enable the integrated production of Hydrogen, as does Zinc Oxide in the course of it's regeneration, do offer, instead, other "fringe" benefits.
Herein, we see that Exxon developed their own version of an Oxygen donor Coal gasification, that, like the Phillips technologies, produces Carbon Monoxide while limiting any co-production of Carbon Dioxide.
And, not only do they limit co-production of Carbon Dioxide, they can actually utilize some of it, recovered, we conjecture as only one possibility, from the off-gas of one of their now almost mythical Ethane Crackers, as one of the agents of Coal gasification, to increase production of the desired Carbon Monoxide.
Further, they have their own way of generating at least some of the Hydrogen needed to formulate, with the Carbon Monoxide, hydrocarbon synthesis gas, as an integral function within the overall process.
Their technology, further, enables not only the integrated removal of Sulfur compounds from the Coal, while Carbon Monoxide and Hydrogen are being generated, but the co-production of commercially-valuable elemental Sulfur, the sale of which would reduce the effective cost of producing that CO-H2 blend.
As explained, with some additional comment and links appended, in our excerpts from the initial link to:
"United States Patent 4,309,198 - Converting Liquid and/or Solid Fuel to a Substantially Inerts-free Gas
Date: January, 1982
Inventor: Gerald Moss, Great Britain
Assignee: Exxon Research and Engineering Company, New Jersey
Abstract: The invention relates to the conversion of fuel (solid and/or liquid) to reducing and/or synthesis gas by contacting the fuel in a fluidized conversion bed with a solid oxygen donor (e.g. CaSO4 - Calcium Sulfate) at a fuel conversion temperature ... in the presence of at least one gas/vapor phase substance such as H2 and/or H2O and/or CO and/or CO2 which serves to promote and or mediate the transfer of oxygen from the donor to the fuel and preferably in the absence of non-reactive gases (e.g. Nitrogen) whereby the fuel is converted to a reducing and/or synthesis gas product by ... partial oxidation employing the oxygen of the solid oxygen donor, the latter being reduced (to Calcium Sulfide, CaS).
The (CaS) is exothermically oxidized in a fluidized oxidation bed by contact with an oxygen-containing gas (e.g. air) and re-used for converting further quantities of fuel. Moieties (e.g. sulfur/sulfur compounds) whose presence is undesirable in the gas product may be removed by a solid moiety-fixing agent (e.g. CaO) in the conversion bed. The moiety-fixing properties of the latter are at least partly regenerated in a fluidized regenerator bed by treatment in a suitable regenerating atmosphere, and the regenerated moiety-fixing agent is returned to the conversion bed directly and/or indirectly via the oxidation bed.
(Don't be put off by the foregoing college-boy speak, especially as regards the unfortunate over-use of the alien word "moiety". As our consultants inform us, it simply means a connected group of atoms that are part of a larger molecule and which are able to interact with other atoms outside the molecule. By way of analogy, think of your hand, which, though a part of your body, can grab hold of other things, like a donut or a hammer, or, be put tightly into other things, like gloves or pockets. In chemistry, "moiety" is basically synonymous with "functional group", and, for more than you ever wanted to know concerning them, see:
Functional group - Wikipedia, the free encyclopedia. What Exxon is starting to tell us in the foregoing is that the Oxygen transfer agent can be regenerated and recycled within the total process, and, that, a mechanism exists in the process for capturing and getting rid of excess Sulfur that is brought into it.)
Claims: A method of converting ... solid carbonaceous fuel to a substantially inerts-free reducing and/or synthesis gas product, said method comprising: passing the fuel into a fuel conversion zone comprising a conversion bed of solid particles which are maintained at an elevated fuel conversion temperature and fluidized by a fluidizing gas which is passed into the bottom of the conversion bed, the conversion bed containing solid particles comprising calcium sulfate which constitutes substantially the sole source of oxygen used in the conversion of the fuel (and ) which is thereby reduced to calcium sulfide whereby a substantially inerts-free reducing and/or synthesis product gas leaves the top level of the conversion bed, the fluidizing gas being substantially free of molecular oxygen and unreactive and/or inert materials which would dilute the gas product.
(Stick with it. The Brits are a wordy lot, but sometimes they're worth listening to.)
(And) transferring solid particles containing calcium sulfide from the fuel conversion zone to an oxidizer bed in an oxidation zone and passing into the bottom of the oxidizer bed a gas containing molecular oxygen at a rate sufficient to fluidize the solid particles in the oxidation bed and to oxidize the calcium sulfide in said solid particles to form said calcium sulfate with the generation of heat which maintains the temperature of particles in the oxidizer bed higher than the temperature of particles in the conversion bed;
(And) transferring the solid particles comprising said calcium sulfate from the oxidizer bed to the conversion bed for use in converting further quantities of fuel in the conversion bed, the solid particles thus transferred to the conversion bed furnishing at least some heat for maintaining the conversion bed at the said elevation fuel conversion temperature.
(Note that heat is generated in one component of the process, which heat can be conveyed into another part of the process to help drive needed chemical reactions, and thereby provide some economies. - JtM)
The method ... in which the said gas phase ... substance in the fluidizing gas passed into the bottom of the fuel conversion bed is selected from hydrogen, a compound which serves as a source of hydrogen under the fuel conversion conditions in the fuel conversion bed, at least one oxide of carbon, and a mixture of at least two of the foregoing.
(As summarized more clearly in the Abstract, "a compound which serves as a source of hydrogen under the fuel conversion conditions in the fuel conversion bed" could be, simply, "H2O"; and, as they also specify, "one oxide of carbon" that can be used is "CO2".
Further, the Claims go on to explain that an excess of Calcium Oxide is added to and maintained in the "oxidizer bed" to, basically, extract and trap excess Sulfur, and remove it from the system. The Calcium Oxide is converted into Calcium Sulfide, CaS, the compound from which the Oxygen donor Calcium Sulfate is formed, but, again, in excess. And, to maintain a materials balance, some of it extracted, with its final disposition left unspecified.
We submit, that, as seen in the sum of equations provided by:
Calcium sulfide - Wikipedia, the free encyclopedia
We can easily react CaS with H2O to make, ultimately, Calcium Hydroxide (CaOH2) and the unpleasant Hydrogen Sulfide (H2S).
The Calcium Hydroxide can then, as seen in:
http://www.netl.doe.gov/
be used in "scrubbers" which are so efficient that they can extract Carbon Dioxide from the atmosphere itself, anywhere there are sufficient air currents available to drive and supply the process, with the ultimate product being Calcium Carbonate, essentially
The Hydrogen Sulfide could find application in a process such as we earlier reported, in:
Exxon Methane and Hydrogen from H2S and Carbon Monoxide | Research & Development; concerning: "United States Patent 4,517,171 - Synthesis of H2 and CH4 from H2S and CO;1985; Exxon Research and Engineering Company; Abstract: Hydrogen and methane are synthesized from a gaseous feed comprising a mixture of H2S and CO";
through reactions with just some of the Carbon Monoxide produced so efficiently by our subject Exxon process of "United States Patent 4,309,198" from Coal, and be made thereby to form both:
Methane, which could be utilized to recycle Carbon Dioxide, reclaimed from whatever source, perhaps thermally extracted from the Calcium Carbonate formed by the above-noted Columbia University and Los Alamos National Laboratory process for "Capturing Carbon Dioxide From Air", via a process such as that described in:
Exxon 2010 CO2 + Methane = Liquid Hydrocarbons | Research & Development; concerning: "United States Patent 7,772,447 - Production of Liquid Hydrocarbons from Methane; 2010; Assignee: ExxonMobil; Abstract: (A) process for converting methane to liquid hydrocarbons ... , including benzene and/or naphthalene, and produce a first effluent stream comprising hydrogen (by) contacting a feed containing methane and ... H2O (and) CO2 with a (specified) catalyst under conditions effective to convert said methane to aromatic hydrocarbons, including benzene and naphthalene, and produce a first effluent stream comprising aromatic hydrocarbons and hydrogen"; and:
Hydrogen, which, combined with the Hydrogen produced by the process of US Patent 7,772,447, immediately above, could, as in a process similar to that described in:
WVU Hydrogenates Coal Tar | Research & Development; concerning the: "Hydrogenation of Naphthalene and Coal Tar Distillate; West Virginia University; 2009; Abstract: The hydrogenation of naphthalene and coal-tar distillates has been carried out in a Trickle Bed Reactor, in which the liquid is allowed to flow through the catalyst bed in the presence of hydrogen (to, ultimately, enable) the direct ... conversion of coal to refinable crude hydrocarbons, from which liquid fuels such as gasoline, diesel, kerosene, etc., can be produced";
enable us to convert some of our abundant Coal directly into such things as "gasoline" and "diesel".
Or, the Hydrogen could be added to the Carbon Monoxide-rich "synthesis gas product" generated by our subject Exxon process herein of "United States Patent 4,309,198", from reactions between their Oxygen donor, Calcium Sulfate, and their somewhat anonymous "solid carbonaceous fuel"; and, that "synthesis gas" could then be catalytically condensed, as seen via:
Fischer–Tropsch process - Wikipedia, the free encyclopedia; "The Fischer-Tropsch process (or Fischer–Tropsch Synthesis) is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons";
into virtually anything we're now economically enslaved to OPEC for the supply of..
Dang. We're getting as wordy as the Brits. With apologies for the excursion, we return to excerpts from that United States Patent 4,309,198.)
The method ... in which the solid oxidizable material is calcium sulfide and the conditions of operation of the oxidation bed are such that substantially none of the calcium sulfide is converted to calcium oxide and substantially no sulfur oxide leaves the top level of the oxidation bed.
(No Sulfur compounds, in other words, are allowed to escape into the environment.)
Description and Summary: The present invention relates to a method of converting ... solid fuel to a substantially inerts-free gas, and more particularly but not exclusively to the conversion of ... carbonaceous (i.e. carbon-containing) fuels ... to reducing gas, useful for the production of heat, power, chemicals and for the reduction of metal oxides.
(Carbon Monoxide, and plain hot Carbon, has historically been used to refine oxide metal ores, as in the steel refining processes that were once common in the northern Ohio Valley. However, it is the "chemicals" that are of most interest to us here.)
The invention is further illustrated by reference to (an) example thereof ... for performing the invention, using coal as the fuel.
(The) method of the invention can be employed for the efficient gasification of (such) fuel to produce a fuel gas of high calorific value and high purity suitable for use as a fuel or as a synthesis gas for use in the production of hydrocarbons, alcohols and other industrial chemicals."
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The immediately-above reference to "using coal", by the way, is one of the only two places in the entire document where Exxon allows our favorite four-letter word to see daylight.
But, that's okay. They also employ the label "solid carbonaceous fuel", and, we sort of prefer that.
It confirms that any number of "carbonaceous" materials, which we'll take to mean sustainable, renewable, and Carbon-recycling products, likely including such things as cellulose, crop wastes and sewage sludge, can be added to the "coal", and used as components of the Exxon-specified "solid carbonaceous fuel" which is converted so efficiently, with zero emissions of "sulfur oxides", into a "synthesis gas product" suitable "for use in the production of