In an earlier dispatch, now accessible via:
we made report of yet another of the many Coal, and other Carbon source, conversion technologies developed by the once-iconic Texaco, since vanished into the Chevron conglomerate.
The specific process is embodied as:
"United States Patent 3,976,442 - Synthesis Gas from Gaseous CO2-Solid Carbonaceous Fuel Feeds; 1976; Inventors: Peter Paull, CT, and Warren Schlinger, CA; Assignee: Texaco, Incorporated, NY; Abstract: This is an improved continuous partial oxidation process for producing synthesis gas or fuel gas from gaseous CO2 (and) solid carbonaceous fuel feeds. A solid carbonaceous fuel such as finely ground coal from a pressurized lock hopper is passed directly into a high pressure high velocity CO2 -rich gas stream which carries the particles of coal into a free-flow non-catalytic gas generator where by the partial oxidation reaction with a free-oxygen containing gas, preferably in the absence of supplemental H2O other than that normally present in the reactants, gaseous mixtures principally comprising H2, CO, CO2, and H2O are produced. A CO2 -rich gas stream is recovered downstream in the process and recycled to the pressurized feed system";
and describes how Coal can be reacted with Oxygen, Water and Carbon Dioxide, to form an hydrocarbon synthesis gas consisting essentially only of Carbon Monoxide and Hydrogen, in relatives ratios that can be controlled to a certain extent, depending on the desired final mix of product hydrocarbons, which, as Texaco specifies in their disclosure of USP 3,976,442, can include "alcohols ... and ... gasoline and diesel fuels".
What might not be very clear in that report is the fact that much of the Carbon Dioxide used in the Coal gasification is actually generated within the total process itself, mostly as a function of the reaction between Carbon Monoxide and Steam, H2O, a "water gas shift" reaction, that serves to generate needed, additional Hydrogen to enrich the Hydrogen content of the product synthesis gas.
Thus, although the process isn't really amenable to recycling Carbon Dioxide from an outside source, it doesn't emit much, if any, Carbon Dioxide itself, which is a big plus; and, more positively, doesn't require the addition of any externally-supplied, and potentially costly, Hydrogen.
There might, as we were advised, be the ultimate potential for some material imbalances to arise as the process was operated over time, with the consequent need to discharge some amount of Carbon Dioxide, unless some additional Hydrogen was independently supplied to the process from outside the system.
That is could well be a feasible, even an economical, possibility, since, as seen in:
More NASA Hydrogen from Water and Sunlight | Research & Development; concerning:
"United States Patent 4,051,005 - Photolytic Production of Hydrogen; 1977; Assignee: United Technologies Corporation; Government Interests: The invention described herein was made in the course of a contract with the National Aeronautics and Space Administration. Abstract: Hydrogen and oxygen are produced from water in a process involving the photo-dissociation of molecular bromine with radiant energy at wavelengths within the visible light region";
there are some technologies available which enable the dissociation of H2O into Hydrogen and Oxygen; and, which utilize only sunlight to drive the process, in conjunction with a co-reactant, Bromine in the case of the above "United States Patent 4,051,005", which isn't itself consumed in the process, but shuttles, cycles, between different reactions as a sort of energy transfer agent.
In any case, the same team of Texaco scientists, coincident with their development of the process of the above "United States Patent 3,976,442", were also at work on a variation of that technology, which was, coincident with issuance of USP 3,976,442, awarded with a patent of its own; a variation which discloses more specifically how Carbon Dioxide is to be utilized in the Coal gasification process; and, which opens up the door, given more recent advances, such as the above-cited "United States Patent 4,051,005", to the actual recycling of Carbon Dioxide reclaimed from a source outside the system.
As we attempt to explain, following excerpts from the initial link in this dispatch to:
"United States Patent 3,976,443 - Synthesis Gas from Solid Carbonaceous Fuel
Date: August, 1976
Inventors: Peter Paull, CT, and Warren Schlinger, CA
Abstract: This is an improved continuous partial oxidation process for producing synthesis gas or fuel gas from a solid carbonaceous fuel. Liquid CO2 and a ground solid carbonaceous fuel such as coal are mixed together to produce a pumpable slurry feed. The CO2 serves as a carrier for the carbonaceous fuel and as a temperature moderator, and is preferably obtained by purifying the product gas.
(Again, the Carbon Dioxide is to be "obtained (from) the product gas", a situation which, it seems to us, will lead to material imbalances unless more and more Coal is added; some extra Hydrogen from outside the system is brought in; or, some of the system-produced CO2 is discharged.)
Claims: A process for producing a gas stream principally comprising gases selected from the group consisting of CO, CO2, H2 H2O, CH4, H2S, COS, N2O, and mixtures thereof comprising:
(We are compelled to interrupt here at some length, to emphasize a few things concerning the specified product gases:
First, the production of "N2O", i.e., Nitrogen Oxide(s) can be minimized if pure, or nearly-pure, Oxygen were used in place of air as the gas which supports the "partial oxidation" of Coal. Such Oxygen could be obtained as the byproduct of a process, such as our above-cited NASA technology of "United States Patent 4,051,005 - Photolytic Production of Hydrogen", which splits Water, H2O, to generate Hydrogen for enriching the product synthesis gas; and, thus minimizes the need for internal generation Hydrogen, with the concomitant generation of Carbon Dioxide, through the specified water gas shift reaction. Thus, one extra external process can minimize or obviate the potential for generating two pollutants, CO2 and N2O, in this process for generating a hydrocarbon synthesis gas from Coal.
Further, since "CH4", i.e., Methane, is one of the product gases, along with "CO2", in addition to the others, it's conceptually feasible that, instead of recycling all of the Carbon Dioxide to the gasification phase, and eventually overwhelming it, the CO2 and the CH4 could be separated and combined, as via a process such as that described, for only one example, in:
Standard Oil 1949 CO2 + CH4 + H2O = Hydrocarbon Syngas | Research & Development; concerning:
"United States Patent 2,460,508 - Method and Means for Hydrocarbon Synthesis; 1949; Assignee: Standard Oil Company; Abstract: This invention relates to ... an improved method and means for producing normally liquid hydrocarbons by reacting hydrogen and carbon monoxide over catalysts ... (and) specifically it relates to hydrocarbon synthesis with methane as the raw material (and, wherein) it is desirable to feed to the reforming operation a gas comprising methane, oxygen and carbon dioxide";
and, be converted through a "reforming operation" into, ultimately, "liquid hydrocarbons".
And, finally, the "H2S", can, as seen in:
Florida Hydrogen and Sulfur from H2S | Research & Development; concerning:
"United States Patent 6,572,829 - Photocatalytic Process for Decomposing Hydrogen Sulfide; 2003; Assignee: University of Central Florida; Abstract: System for separating hydrogen and sulfur from hydrogen sulfide (H2S) gas produced from oil and gas waste streams. Hydrogen sulfide (H2S) gas is passed into a scrubber and filtration unit where it encounters polysufide solution. Elemental sulfur is freed and filtered through a porous media and continues to a stripper where excess H2S is removed. The excess H2S returns to the scrubber and filtration unit, while the sulfide solution passes into a photoreactor. The sulfide solution inside the photoreactor is oxidatively converted to elemental sulfur and complexed with excess sulfide ion to make polysulfide ion, while water is reduced to hydrogen. Hydrogen percolates out of the photoreactor, while the polysulfide solution is fed back to the scrubber where the system starts over";
be broken down, through the use of environmental energy, into it's elemental constituents of Sulfur, which would be a byproduct of commercial value, and Hydrogen, which could be recycled back into the process of our subject, "United States Patent 3,976,443 - Synthesis Gas from Solid Carbonaceous Fuel".)
(a) mixing liquid CO2 and solid particles of carbonaceous fuel together in a mixing zone at a temperature in the range of above about -69.degree. to 80.degree.F. and a pressure in the range of about above the triple point pressure of carbon dioxide to about 1000 psia to produce a substantially water-free pumpable slurry;
(b) introducing the mixture ... at a temperature in the range of about about -69 to 1200F. and pressure in the range of above about 76 to 4500 psia, and simultaneously introducing a stream of free-oxygen containing gas selected from the group consisting of air, oxygen-enriched air (greater than 21 mole % O2), and substantially pure oxygen (greater than 95 mole % O2) at a temperature in the range of about 80 to 500F. and a pressure in the range of above about 76 to 4500 psia, into the reaction zone of a free-flow noncatalytic gas generator; and:
(c) reacting said carbonaceous fuel and free-oxygen containing gas by partial oxidation in said reaction zone at an autogenous temperature in the range of about 1200 to 3000F and a pressure in the range of above about 30 to 4400 psia to produce said product gas stream.
(As in the above claims and sub-claims, broad ranges of starting temperatures and pressures are acceptable, with the final, higher, reaction temperatures being "autogenous", that is, generated within the reaction itself by the partial oxidation of the Coal.)
The process ... wherein the weight ratio of CO2 to carbonaceous fuel ... is in the range of about 0.6 to 2.0.
(Now, note: We can, according herein to Texaco, use, by weight, twice the amount of Carbon Dioxide as we do Coal in the initial gasification process. We submit that it would be a physical and chemical impossibility to generate twice the weight of CO2, relative to Coal, in a process where some significant amount, greater than half, of the Coal, or other initial Carbon, was being converted into final product Carbon Monoxide. If we can, in fact, use twice as much CO2, by weight, as Coal, and we should, one would think, use as much as we can, then we would, almost without doubt, have to import some of it from outside the system.)
The process ... wherein H2O at a temperature in the range of about 50 to 1000F and in an amount to provide a weight ratio H2O to carbonaceous fuel in the range of 0.01 to 0.15 is introduced into the reaction zone ... .
(The water, H2O, is added for the extra Hydrogen that can be derived from it. However, it also brings additional Oxygen into the reaction, with the resulting potential to form more, to a certain extent energy wasteful, Carbon Dioxide. Keep in mind that, as seen in:
California Rocket Scientists Liquefy Coal | Research & Development; concerning, in part:
"United States Patent 4,243,509 - Coal Hydrogenation; 1981; Rockwell International Corporation; Abstract: Disclosure is made of a method and apparatus for reacting carbonaceous material such as pulverized coal with heated hydrogen to form hydrocarbon gases and liquids suitable for conversion to fuels";
we can react elemental Hydrogen, instead of H2O, with Carbon to achieve the same ends; but, without generation of byproduct CO2. Both reactions are endothermic, and both require the addition of some heat, as in the above "temperature in the range of about 50 to 1000F", so the energy penalty of using pure H2 might not be that great, especially if balanced against the energy saved by not having to, also via an endothermic process, react co-product CO2 with Carbon in the system to reduce it to Carbon Monoxide.)
The process ... wherein said solid carbonaceous fuel is selected from the group consisting of coal, coke from coal, char from coal, ... particulate carbon soot, ... lignite, rubber, rubber tires and mixtures thereof.
(The waste "rubber" and "rubber tires", composed as they are of both natural and synthetic polyemers, are only a few of the Carbon-recycling wastes which can, in a process empowered by Coal, be converted, along with Coal, into a hydrocarbon synthesis gas. See, for example:
West Virginia Coal Association | California Hydrogasifies Coal & Carbon-Recycling Wastes | Research & Development; concerning:
"United States Patent 7,500,997 - Steam Pyrolysis ... to Enhance the Hydro-Gasification of Carbonaceous Materials; 2009; Assignee: The Regents of the University of California; Abstract: A process and apparatus for producing a synthesis gas for use as a gaseous fuel or as feed into a Fischer-Tropsch reactor to produce a liquid fuel in a substantially self-sustaining process. (And) wherein the carbonaceous material comprises municipal waste, biomass, wood, coal, or a natural or synthetic polymer". - JtM)
Background and Field: This invention relates to a continuous process for the production of a CO-rich gas stream by the partial oxidation of a carbonaceous fuel. More specifically, the present invention relates to the production of synthesis gas by noncatalytic partial oxidation starting with liquid CO2, solid carbonaceous fuel e.g. ground coal, and a free-oxygen containing gas e.g. air, or substantially pure oxygen.
Oil embargoes coupled with already developing petroleum shortages have led to an energy crisis in this country (and) long-term solutions demand that alternate energy resources be developed and utilized to the maximum degree.
Coal is the most promising raw material in the USA for the production of synthetic natural gas (SNG) and synthesis gas i.e. mixtures of CO+H2. In the U.S. in 1970 the estimated recoverable coal reserves assuming 50 percent recovery were about 778 billion short tons. In comparison in the U.S. in 1974 the proved reserves of crude oil amounted to about 35 billion barrels.
Nothing in the prior art teaches or suggests the subject invention wherein liquid carbon dioxide is mixed with a solid carbonaceous fuel e.g. ground coal to produce a pumpable slurry which is fed to an unpacked free-flow noncatalytic gas generator, where reaction takes place by partial oxidation to produce a CO-rich synthesis gas or fuel gas.
Summary and Description: This is a continuous process for producing a gas stream principally comprising gases selected from the group consisting of CO, CO2, H2, H2O, CH4, H2S, COS, N2, and mixtures thereof comprising: mixing liquid CO2 and solid particles of carbonaceous fuel together in a mixing zone to produce a substantially water-free pumpable slurry; introducing said slurry at a temperature in the range of above about - 69.degree. to 1200.degree.F. and free-oxygen containing gas into the reaction zone of a free-flow noncatalytic gas generator; and reacting said carbonaceous fuel and free oxygen containing gas by partial oxidation in said reaction zone at an autogenous temperature in the range of about 1200 to 3000F. and a pressure in the range of above about 30 to 4400 psia.
(As detailed in the full Disclosure, but not reflected in our excerpts, the above "H2S" component is, as explained further on, to be separated and, the "H2S-rich gas stream is (then) sent" as Texaco specifies, "to a Claus unit for sulfur recovery"; or, as we suggested above, to a conceptually-related Sulfur recovery process such as that disclosed by the University of Central Florida, in their "US Patent 6,572,829".)
The present invention pertains to an improved continuous partial oxidation process for producing gas mixtures containing for example H2 and CO starting with slurries of liquid CO2 and solid particles of carbonaceous fuel."
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We confess that much of the "liquid CO2", which is reacted with the Coal, and other "solid particles of carbonaceous" matter in the initial gasification, seems to be a product of further steps in the process of "United States Patent 3,976,443", wherein some of the product Carbon Monoxide reacts with Steam, H2O, in a water gas shift reaction to form some of the needed Hydrogen, with Carbon Dioxide as a byproduct which is recycled back to convey Coal into the gasification process.
We submit that provision could be made to import significant amounts of Carbon Dioxide from a source outside the system, and thereby effect a net recycling of CO2, if additional, supplemental Hydrogen could be added to the process, perhaps from the above-cited University of Central Florida's "United States Patent 6,572,829 - Photocatalytic Process for Decomposing Hydrogen Sulfide", where any Hydrogen Sulfide generated during the initial Coal, and other Carbon, gasification could be processed; or, perhaps, from a process similar to that of the above-cited "United States Patent 4,051,005 - Photolytic Production of Hydrogen", or similar, such as that reported in:
West Virginia Coal Association | Germany Makes Economical Hydrogen from H2O | Research & Development; concerning:
"United States Patent Application 20090026089 - System and Method for Splitting Water; 2009; Assignee: Hermsdorfer Institut, Germany; Abstract: The present invention relates to a system and a method for cleaving water by means of hyperpolarisation, the system comprising a first electrode and at least one additional electrode; at least one porous ferroelectric layer arranged between the first and the additional electrode; as well as an AC voltage or pulsed DC voltage source. With the method according to the present invention it is possible to cleave the water economically into hydrogen and oxygen and obtain gases for technical purposes. The method is even more environmentally friendly if AC voltage originating from solar energy is (utilized)."
The "AC voltage" could, of course, be generated by something other than "solar energy" in our beloved, but often cloudy, hills; if, for example, a process similar to the above, such as that disclosed in our report of:
Hydrogen from Wind Power | Research & Development; concerning:
"United States Patent 7,329,099 - Wind Turbine and Energy Distribution System; 2008; Inventor: Paul Hartman, Ohio; A wind electric system, wherein the apparatus ... is coupled to electrical generating means, and said electrical generating means is connected to an electrical load, whereby; said rotational power is converted to electrical power delivered to said electrical load; (And, which) electrical load comprises at least one electrolysis cell, said at least one electrolysis cell connected to an output stream of hydrogen gas and further connected to an input stream of water",
were to be installed at a site like that described in:
Beech Ridge Wind Farm - Wikipedia, the free encyclopedia; wherein we're told, that: "The Beech Ridge Wind Farm is a ... 119-wind turbine wind farm under construction in Greenbrier County, West Virginia. The 400 feet (120 m) tall wind tubined, each of which generates 1.5 megawatts of electricity, will be scattered for 15 miles (24 km) along Shellcamp, Smokehouse, Beech, Rockcamp and Big ridges and Cold Knob, Old Field, Blue Knob and Nunly Mountains. It is served by a new 13.8 miles (22.2 km), 138 kilovolt power transmission line, located in Greenbrier and Nicholas counties, tied to an electrical substation near Nettie, West Virginia. When completed, total output for the project will be 186 megawatts".
The same sorts of possibilities exist, as we've separately reported, for engaging Coal Country's abundant hydroelectric potentials to accomplish the same ends.
The point of it all being, that, if we were to engage some of our abundant environmental energy to generate a little Hydrogen, then, we could begin to utilize our abundant Coal, "the most promising raw material in the USA for the production of synthetic natural gas (SNG) and synthesis gas", in a process that consumes some of our organic wastes, such as used "rubber tires", and Carbon Dioxide, to manufacture hydrocarbon "synthesis gas or fuel gas".
It just seems to us, on our end, that there exist herein some extraordinary opportunities for Coal Country people of all sorts and outlooks to put their heads together and figure out how we can all work together, in at least a few ways we might all have some sort of agreement on, to start more wisely using our most abundant natural resource, Coal, and some of our abundant environmental energy potentials, to start cleaning up some of our organic wastes and recycling some of our Carbon Dioxide, in processes that result in the production of hydrocarbons that could benefit us economically, change the world politically in beneficial ways, and, clean up the environment a little.
Is there some reason we're not aware of here, in our cloistered, shunned little cell, that US citizens of all stripes wouldn't want to at least know about those possibilities and potentials, and openly discuss them?