There should be nothing really, on a technical basis, conceptually new for you, presuming you to have followed our reports thus far, revealed by the Gulf Oil Corporation Coal gasification technology, confirmed as being viable by our own US Government, that we disclose herein.
Their intent is, simply, to generate as pure a mixture of Carbon Monoxide and Hydrogen synthesis gas, suitable for catalytic condensation, as via, for example, the Fischer-Tropsch process, into liquid hydrocarbon fuels, as possible.
And, they attain that goal by, as a function of the overall process, first generating a gas stream, from Coal, gas that contains a large percentage of Carbon Dioxide and Steam, with which they then gasify more Coal.
That has implications which should be obvious; but, we'll be sure to beat them to death for you as we go along, since there's been no indication to us yet that anyone's been picking up on 'em.
Comment follows, and is inserted within, our excerpts from the link to:
"United States Patent 3,971,635 - Coal Gasifier Having An Elutriated Feed Stream
(Don't be distracted by the "Elutriated" techno-jargon. It just means that particles of Coal have been classified and separated according to size and weight, a procedure accomplished by a stream of air. The "elutriation" herein is performed to separate the Coal particles into two separate streams, the purpose for which will become clear.)
Date: July, 1976
Inventor: Charles Matthews, Pennsylvania
Assignee: Gulf Oil Corporation, Pittsburgh
Abstract: A process for gasifying coal to produce carbon monoxide and hydrogen in which a first stream of coal is burned without bed formation in a combustion zone in the presence of water under oxidation conditions to produce gases containing carbon dioxide and steam. A second stream of coal is maintained as a fluid bed in a separate gasifier zone by upflowing carbon dioxide and steam from the combustion zone while being gasified under reducing conditions to produce carbon monoxide and hydrogen.
(We must note, as we will further emphasize, that: The initially-produced "carbon dioxide and steam" are reacted with a "second stream of coal ... to produce carbon monoxide and hydrogen". And, we urge you to keep in mind that we can, alternatively, as exemplified for one instance in:
Bayer Improves Coal + CO2 = Carbon Monoxide | Research & Development; concerning: "United States Patent 7,473,286 - Carbon Monoxide Generator; 2009; Bayer Material Science, AG, Germany; Carbon monoxide gas is ... produced in the art by means of a continuous process in which carbon-containing raw materials are reacted with oxygen and carbon dioxide";
react Carbon Dioxide recovered, separately, from whatever source, with hot Coal, and thus convert them both into Carbon Monoxide, and, that, we could supply Steam separately to the hot Coal as well, perhaps generated by a process that relies on renewable, environmental energy, along with the Carbon Dioxide, much as described in:
USDOE Hydrogasifies Coal with Solar Power | Research & Development; concerning: "United States Patent 4,415,339 - Solar Coal Gasification Reactor; 1983; The USA, as represented by the Department of Energy; Abstract: A method of producing a ... product gas with a solar reactor from ... coal and ... at least one reactive gas selected from the group consisting of steam (and) CO2".)
Feed coal for both streams is first passed through a crusher and the crushed coal is elutriated to remove coal fines, which are too small to be retained in the gasifier fluid bed, from coarse particulates. The elutriated fines are water scrubbed to form a slurry, which comprises at least in part said first stream of coal entering the combustion zone, while the coarse particulates comprise said second stream of coal.
Claims: A process for gasifying feed ash-containing coal comprising crushing a feed coal stream to produce relatively large particulates and relatively small coal feed particulates, elutriating said relatively small feed particulates from said relatively large feed particulates, passing said relatively small feed particulates and at least one member selected from the group consisting of water and steam in addition to an oxygen-containing gas to a combustion zone to provide heat and reactants for said process
(And) passing said relatively large feed particulates to a fluidized bed gasifier zone disposed upon grate means with said large feed particulates entering said gasifier zone above said grate means, maintaining said combustion zone under exothermic oxidation reaction conditions including a temperature between 2200.degree. and 3300.degree.F. and a residence time of up to 30 seconds to produce hot combustion gases and steam and to convert ash into molten slag, passing said hot combustion gases and steam upwardly from said combustion zone through said grate means into said fluidized gasifier zone to form a fluidizied bed of said relatively large feed particulates having a pseudo-liquid level.
(And) injecting at least one coolant selected from the group consisting of water and steam into said hot combustion gases between said combustion zone and said grate means to solidify molten slag in said hot combustion gases, maintaining said gasifier zone under endothermic reducing conditions including a temperature between 1400. and 2000F, and a pressure of at least 10 psi at which carbon dioxide and water vapor react with carbon to produce carbon monoxide and hydrogen,
(Note, again, above, the critically important: "carbon dioxide and water vapor react with carbon to produce carbon monoxide and hydrogen".)
Description: This invention relates to a process for gasifying coal ... to produce a gaseous mixture which, after removal of carbon dioxide and hydrogen sulfide, is composed mainly of carbon monoxide and hydrogen.
(Again, most of the "removal of carbon dioxide" is effected by reacting it with more hot Coal.)
The gaseous product may be utilized ... in coal conversion plants for manufacture of coal liquids ... .
In accordance with the present invention, coal is converted to carbon monoxide and hydrogen by a process which exhibits a minimum potential for polluting.
Essentially no water effluent is produced. Water makeup for use within the process as steam for gasification or as wash water may include polluted, solids-containing water from other processes. As a result, process requirements for fresh water are greatly reduced, and conventional requirements for purification and discharge of process waste water are similarly reduced.
Ash, entering as part of the coal feed, is removed from the process in the oxidized form as solidified slag, suitable for ... additional processing to recover valuable minerals.
Essentially no ash or other solids is rejected to the atmosphere.
Gaseous impurities, having a potential for pollution, which are generated within the process are treated within the process and converted into acceptable forms for sale or disposal, or the impurities are destroyed within the process.
For example, sulfur compounds entering the process are converted to hydrogen sulfide directly, or to sulfur dioxide and then to hydrogen sulfide; the hydrogen sulfide is recovered by known processes; and the recovered hydrogen sulfide is converted to elemental sulfur for sale or storage by use of known processes.
(We submit that one of those "known processes" for the "use" of the co-produced "hydrogen sulfide" could and should include the process disclosed in our report of:
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";
wherein the "CO" could be made by the above-referenced Bayer process of "US Patent 7,473,286 - Carbon Monoxide Generator", from hot Coal and Carbon Dioxide.)
Nitrogen compounds entering the process are converted mainly into ammonia, or to nitrogen gas, or to nitrogen oxides and then to ammonia or nitrogen gas; the ammonia is recovered and purified by known processes for sale.
(Again, keep in mind: Nearly all of the Carbon Dioxide produced in the first gasification zone is converted, through reaction with hot Coal, into the desired product Carbon Monoxide in the second gasification zone. Such a reaction process is more fully explained in our earlier report of:
Texaco CO2 + Coal = Hydrocarbon Synthesis Gas | Research & Development; concerning: "United States Patent 3,976,442 - Synthesis Gas from Gaseous CO2-Solid Carbonaceous Fuel Feeds; 1976; Texaco, Incorporated; Abstract: This is an improved continuous partial oxidation process for producing synthesis gas or fuel gas from gaseous CO2 (and) solid carbonaceous fuel feeds".)
Any traces of oils and tars which may be formed within the process are treated at high temperature to cause thermal cracking and are thereupon converted to gaseous or solid materials which are further reacted to form the desired gas product.
At the same time, the improvements of the present process enhance process economy, especially in water usage, in process heat utilization, and in reliability.
Another advantage of the present process is its flexibility in using a variety of conventional fuels, combustible wastes, and potential pollutants as a source of heat for gasification of coal. These combustible materials may have high sulfur content, high ash content, high moisture content but still would be useable.
(See, for example, our report of:
Exxon Co-Gasifies Coal and Carbon-Recycling Biomass | Research & Development; concerning: "US Patent Application 20100083575 - Co-gasification Process for Hydrocarbon Solids and Biomass; 2010; Assignee: ExxonMobil Research and Engineering Company; Abstract: A process for the co-gasification of carbonaceous solids (coal) and biomass";
for a better explanation of how "high moisture content" Carbon-recycling materials can be co-gasified with Coal, to, as does Gulf Oil herein, produce a synthesis gas blend of Carbon Monoxide and Hydrogen.)
Such fuels are injected into the combustion zone where oxidation occurs. Sulfur oxides and nitrogen oxides which may be formed initially are ultimately reduced to hydrogen sulfide and nitrogen gas or ammonia within the process for easy separation and conversion to acceptable forms. Ash is melted and the slag withdrawn from the process with coal ash slag.
Associated moisture is vaporized, superheated, and is reacted with coal to form the desired gas product.
Most water is consumed within the process by the chemical reaction: C + H2O = CO + H2, and is thereby converted to the desired gaseous product. Only small amounts of water are lost as moisture vapor contained in vented non-polluting gas streams. Makeup process water does not need to be treated, and, in fact, solids-containing and polluted water from other processes may be used.
(Note: This Coal gasification process could, in fact, also serve as a waste, "polluted water" treatment and disposal system.)
Some of the advantages of process water economy and process heat economy are achieved interdependently. Water is used at many locations throughout the process to scrub particulates from gas streams and to cool hot particulates. The resulting slurry contains substantially all the ash from the process plus associated combustible material and dissolved pollutants. After settling, clarified water is recycled for additional scrubbing and cooling duties; the thickened, concentrated slurry is pumped at a controlled rate to the combustion chamber of the process where the combustibles are burned with oxygen to supply process heat; the slurry water is vaporized and superheated for reaction with coal; and the ash is melted to form slag which is easily separated from the process. In this manner, essentially no combustible carbonaceous matter is withdrawn from the process as byproduct or waste, and the process can accept and usefully burn undesirable high-sulfur, high-ash combustibles which are byproducts or wastes from other processes, such as the high-sulfur, high-ash solid wastes of a solvent coal liquefaction process.
(And) pollutants contained in the slurry water such as phenols, cyanides and other nitrogenous substances, and various sulfur compounds are destroyed in the combustor as a result of combustion with oxygen and exposure to very high temperatures. The combustor conditions are chosen to generate a maximum of useful heat for the gasifier while avoiding vaporization of excessive amounts of water. As a result, combustor conditions may be chosen ranging from virtually total combustion of carbon to carbon dioxide to combustion primarily to carbon monoxide with a much reduced yield of carbon dioxide.
(Note, again, the pollution-abating potentials of this Coal-based process. Since "phenols, cyanides and other nitrogenous substances" can be entrained in the "slurry water" with which Coal is gasified, the potential would seem to exist to utilize, and destroy the wastes in, effluent from some chemical industries.)
Similarly, a combustible solid material (or gaseous or liquid) which is otherwise not useful as fuel because of the polluting character of its combustion gas can be utilized as combustor fuel. An example is the high-sulfur carbonaceous residue (perhaps containing diatomaceous earth filter aid) from a coal solvent liquefaction process. This residue can be added to the slurry system of the present process or can be charged directly to the combustor. Ordinarily, such a residue contains so much sulfur that it cannot be burned without an unacceptably high sulfur dioxide emission. When burned in the present process, the sulfur dioxide produced, which is very difficult or impossible to treat in a commercial manner, is converted to hydrogen sulfide in the gasifier and can then be easily recovered by known processes as elemental sulfur without the possibility of pollution.
(For examples of related technology involving the gasification of "carbonaceous residue ... from a coal solvent liquefaction process", see:
Consol Hydrogasifies CoalTL Residues | Research & Development; concerning: "United States Patent 4,248,605 - Gasification of Coal Liquefaction Residues; 1981; Assignee: Conoco, Inc.; A method for gasifying the bottoms fraction from a coal liquefaction process"; and:
Mobil Oil Converts CoalTL Residues to Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 4,583,993 - Carbon Monoxide and Hydrogen from Carbonaceous Material; 1986; Assignee: Mobil Oil Corporation; Claims: A method for producing separate streams of hydrogen and carbon monoxide of relatively high purity from a char like product selected from the group consisting of ... (the) char product of coal solvation".)
An additional purpose of the combustor is to cause the oxidation and destruction of water soluble pollutants such as phenols, cyanides, sulfur compounds, and ammonia contained in process water streams from this process and from external processes, thereby enormously reducing waste water treatment requirements of this and associated processes and providing the means that stringent environmental regulations may be readily met."
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Actually, "environmental regulations" should be more than "readily met" by this technology, since, in addition to minimizing or eliminating the emission of pollutants from the Coal gasification itself, the process enables the inclusion, and destruction and conversion into hydrocarbon synthesis gas, of any number of organic, and potentially hazardous, wastes.
Further, though not reflected well in our excerpts, Gulf demonstrates through accompanying equations that much of the Carbon Dioxide generated in the first gasification zone is converted into Carbon Monoxide, through reaction with hot Coal, in the second gasification zone, as indicated for one instance in their specification, as reproduced above, of reaction conditions in "which carbon dioxide and water vapor react with carbon to produce" the desired "carbon monoxide and hydrogen".
Any minimal Carbon Dioxide "slip", or pass-through, should be more than off-set by the ability of this technology to process and utilize, as Gulf suggests, "combustible wastes, and potential pollutants (which) may have high sulfur content, high ash content (and) high moisture content", which "combustible wastes", we submit, would include at least some of the naturally CO2-recycling "biomass" suggested by ExxonMobil, in their above-cited process of "US Patent Application 20100083575 - Co-gasification Process for Hydrocarbon Solids and Biomass".
And, what the heck, since Gulf does indicate that some "slag" is produced as waste from their CO2-free Coal gasification process herein, that disclosed by our subject "United States Patent 3,971,635", keep in mind, that, as we reported for one instance in:
Exxon Converts Coal Conversion Residues to Cement | Research & Development; concerning: "United States Patent 4,260,421 - Cement Production from Coal Conversion Residues; 1981; Assignee: Exxon Research and Engineering Company; Abstract: Cement is produced by feeding residue solids containing carbonaceous material and ash constituents obtained from converting a carbonaceous feed material into liquids and/or gases into a cement-making zone and burning the carbon in the residue solids to supply at least a portion of the energy required to convert the solids into cement";
even the inorganic mineral wastes resulting from a complete and thorough Coal conversion process that consumes and productively utilizes virtually all of the original Carbon content in the Coal, can still find beneficial and profitable employment.