The latter months of the year 1975, from whence the principal subject of our discussion herein originates, were, in terms of Coal conversion science and technology, busy ones both for our United States Patent Office and for the companies that some decades later found themselves getting homogenized into Chevron.
Texaco was one of those companies; and, we have documented their mid-1970's development of a variety of Coal utilization and conversion technologies in a number of prior reports.
For instance, as seen in:
Texaco 1975 Coal to Methanol | Research & Development; concerning: "US Patent 3,920,717 - Production of Methanol; Date: November, 1975; Assignee: Texaco Development Corporation, NY; Abstract: A continuous process for producing methanol (from) a hydrocarbonaceous feed (and) wherein said hydrocarbonaceous feedstock (can include) coal tar, coal oil, (and) pumpable slurries of coal ... in water";
Texaco developed, late in the year 1975, a technology for converting Coal into the liquid fuel, Methanol.
That achievement should have immediately been seen as one of rather immense value, since, as in:
"United States Patent: 4035430 - Conversion of Methanol to Gasoline; 1977; Assignee: Mobil Oil Corporation, NY; Abstract: The conversion of methanol to gasoline";
it was soon afterward demonstrated that we could convert such Methanol into Gasoline. And, as seen in:
1973 oil crisis - Wikipedia, the free encyclopedia, wherein we're toldt: "The 1973 oil crisis started in October 1973, when the members of (the) Organization of Arab Petroleum Exporting Countries .. proclaimed an oil embargo ... "in response to the U.S. decision to re-supply the Israeli military" during the Yom Kipppur War";
we already should have had the sense to, and have known, to start doing so - - in order to defend ourselves against any further economic warfare that could be waged against us, by those who didn't happen to agree with the foreign policies established and followed by our own democratically-elected US leadership .
Innovative and proactive companies, like and especially Texaco, in fact, had also set to work on the development of technologies that would have enabled us to start converting our abundant Coal into anything we were dependent on stuff that came up out of a well for the supply of, since, as we reported in:
Texaco 1975 Methane from Coal | Research & Development; concerning: "US Patent 3,922,148 - Production of a Methane-rich Gas; November, 1975; Inventor: Edward Child, NY; Assignee: Texaco Development Corporation; Abstract: This is an improved continuous process for producing a clean methane-rich gas stream (from Coal. And, the) product ... may have a methane content up to 98 to 99 mole percent";
Texaco also, in that same time frame, were developing the technology to efficiently convert Coal into the primary constituent of natural gas, Methane.
And, we submit herein even further testament to the fact that Texaco, in the person of the named inventor of US Patent 3,922,148, developed even more technology, in the very same year, that would have allowed us to start converting even our less-expensive and less-pure Coals into such nearly-pure Methane.
Comment follows excerpts from the initial link in this dispatch to:
"US Patent 3,928,000 - Clean Methane ... from High-Sulfur Containing Hydrocarbonaceous Materials
Date: December, 1975
Inventors: Edward Child, et. al., NY and CA
Assignee: Texaco Incorporated, NYC, NY
Abstract: This is an improved process for converting low-cost high-sulfur containing hydrocarbonaceous materials into a clean methane-rich gas stream which may be burned as a fuel without contaminating the atmosphere.
A high-sulfur hydrocarbonaceous fuel is gasified by partial oxidation to produce a process gas stream which is cooled, cleaned and subjected to catalytic methanation over a sulfur-resistant catalyst comprising 0.8 to 10 atoms of an element selected from the group comprising Co, Cr, W or mixtures thereof per atom of an element selected from the group Mo, Ni, or mixtures thereof.
The catalyst may be supported on a structure formed from Group III and IV elements e.g. alumina, silica stabilized alumina, zeolite.
(Nothing too expensive or exotic, in other words.)
A distinct advantage of the subject process, is that the sulfur in the process gas stream is not removed prior to the methanation step. Rather, the sulfur is permitted to remain in the process gas stream in order to moderate the highly exothermic methanation reaction.
After cooling and purification ... the resulting methane-rich gas stream comprises (up to) 95% CH4.
Optionally, the CH4 (Methane) content of said methane-rich gas stream may be increased to about 98% or more by the additional steps of water-gas shift conversion, catalytic methanation, cooling, drying and CO2 removal.
(Note, as above, in the improvement from "95% CH4" to "98%", such improvement is due only in part to "CO2 removal", and, thus, Carbon Dioxide must be co-produced only in very, very minor quantities.)
Claims: A process for producing a methane-rich gas from a sulfur-containing hydrocarbonaceous fuel comprising the steps of ... reacting said sulfur-containing hydrocarbonaceous fuel feed by partial oxidation with substantially pure oxygen comprising 95% O2 or more and a temperature moderator from the group H2O, CO2, and mixtures thereof.
(Note that, in confirmation of many of our earlier reports, Carbon Dioxide can be recycled through the use of it as an agent, along with Water, for the gasification of Coal. The reaction of CO2 with hot Coal, yields reactive, and quite useful, Carbon Monoxide. )
The process ... wherein said sulfur-containing hydrocarbonaceous fuel contains from about 1 to 7% sulfur and is (a slurry) of coal ... (in liquid.
(And) introducing supplemental H2O into the (initial product) gas stream ... to provide a ratio of CO/H2 O in the range of about 0.3 to 1.0 (and) reacting (that) gaseous mixture ... in a catalytic water-gas shift reactor to provide an effluent gas stream having a ratio H2 /(CO+CO2) in the range of about 1 to 4;
(And) reacting substantially all of the H2 and carbon oxides contained therein over a conventional methanation catalyst ... ; and (condensing) H2O, and removing CO2 to produce a product gas comprising about 98 or more % CH4.
The process ... wherein ... said CO2 is obtained at least in part from the (product) gas separation zone.
(Note: Though not reflected in our excerpts, Carbon Dioxide is used both as a reactant and as a "temperature moderator". And, to be clear: The reaction that converts Carbon Dioxide into Methane is "endothermic", and requires the addition of heat to take place. The reaction that converts Carbon Monoxide into Methane is "exothermic", and generates heat. Texaco describes herein a process where the two gases can be converted into Methane together, with the CO-to-Methane reaction providing the heat needed to drive the CO2-to-Methane reaction. The trick is in balancing the amounts of the two gases, and, since the process can effectively use more CO2 than is co-generated in the process itself, as implied in the "CO2 is obtained" only "in part from the gas separation zone", the potential exists, as in other, similar Coal conversion processes we've reported, to import Carbon Dioxide from a source external to the system into the reaction.
And, that use of Carbon Dioxide would be in addition to the potentials for utilizing it in the initial Coal gasification itself, to participate in the "partial oxidation" of the raw Coal, which potentials, though not really discussed by Texaco herein, have been explained in other venues by Texaco, and by others, as in, for just one instance, our earlier report:
Texaco CO2 + Coal = Hydrocarbon Synthesis Gas | Research & Development | News; concerning: "United States Patent 3,976,442 - Synthesis Gas from Gaseous CO2-Solid Carbonaceous Fuel Feeds; 1976; 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".)
The process ... wherein ... the sulfur-containing hydrocarbonaceous fuel feed ... comprises a pumpable slurry of a solid ... particulate carbon separated (out of the product in another step the process, and) coal ... in admixture with a liquid selected from the group consisting of liquid hydrocarbon fuel and water.
(And) wherein said ... liquid hydrocarbon (is) selected from the group consisting of ... coal tar, coal oil ... and mixtures thereof.
This invention relates to a continuous process for the production of a clean methane-rich gas stream from a high-sulfur containing fuel. More specifically, the present invention relates to the production of clean gaseous heating fuels from low cost high-sulfur containing hydrocarbonaceous materials. Further, the product gas may be burned without polluting the environment.
Background and Field: It is imperative that alternate sources of low-cost gaseous heating fuels be developed which will not pollute the atmosphere when burned.
In prior art catalytic methanation processes it was necessary to keep the sulfur content of the process gas stream below 0.1 parts per million (p.p.m) so as not to poison the methanation catalyst. When hydrocarbonaceous materials containing more than about 500 ppm of sulfur are used as fuels they require expensive processing to remove sulfur. In order to increase the life of conventional methanation catalyst in prior art processes, it is necessary to reduce the (Sulfur compound) content of the process gas stream prior its introduction into the methanation zone. In contrast, by means of the subject invention, sulfur remains in the process gas stream and goes into the catalytic methanation zone.
Summary: This is a process for producing a methane-rich gas comprising CH4 in the range of (up to) 95% (dry basis) or optionally 98% CH4, or more from a sulfur-containing hydrocarbonaceous fuel such as from high-sulfur ... coal.
The process steps comprise: reacting the sulfur-containing hydrocarbonaceous fuel feed by partial oxidation with substantially pure oxygen and a temperature moderator ... in the reaction zone of a free-flow unpacked noncatalytic synthesis gas generator (under specified conditions) to product a stream of effluent gas.
(And, remember: The "temperature moderator", which participates in and is consumed by the Coal gasification, as above, consists of "H2O, CO2, and mixtures thereof".)
Further, particulate carbon and any other entrained solids may be removed from the effluent gas stream by well known scrubbing techniques in a gas-liquid scrubbing zone. For example, the particulate carbon may be removed by scrubbing the process gas with a scrubbing fluid comprising oil, water, or both. The slurry of particulate carbon and scrubbing fluid may be recycled to the gas generator as a portion of the hydrocarbonaceous feedstock.
The effluent gas stream from the ... methanation zone is passed through a waste heat boiler and cooled to a temperature of about 400F. by converting water into steam."
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And, which co-product "steam", H2O, we again remind you, can be combined, as above, in a "temperature moderator" gas consisting of "H2O, CO2, and mixtures thereof", with that mix then used to increase the production of both Hydrogen and Carbon Monoxide from the initial "sulfur-containing hydrocarbonaceous fuel feed", which is specified to include "high-sulfur ... coal"; and, to, thus, serve in increasing the production of a gas "comprising CH4 in the range of (up to) 95% (dry basis) or optionally 98% CH4, or more".
Further, as in a closely-similar Coal-to-Methane technology we earlier reported, as available via:
Exxon Converts 99% of Coal to Methane | Research & Development; concerning: "USP 4,077,778 - Process for the Catalytic Gasification of Coal; 1978; Assignee: Exxon Research and Engineering Company, NJ; Abstract: A process for the production of synthetic natural gas from ... coal, by reaction ... with water (steam) in the presence of a mixture of hydrogen and carbon monoxide (both made within the system ...), in a ... further improved coal gasification process";
by reclaiming the particulate Carbon and the Carbon Dioxide that might be passed through, or produced in, the various series of staged reaction zones, and recycling them both back into the initial Coal gasification process, not only can essentially pure "98% CH4" be produced, but, virtually all, up to "99%", as Exxon specifies in their full Disclosure of "USP 4,077,778", of the Carbon content in the Coal can be so converted into CH4, i.e., Methane.
And, as desirable as such Coal-based Methane, in and of itself, might be, we remind you that, as seen in:
1941 CO2 + Methane = Liquid Hydrocarbon Fuels | Research & Development; concerning: "United States Patent 2,243,869 - Method of Synthesizing Liquid Hydrocarbons; 1941; Assignee: M.W. Kellogg Company; Abstract: Our invention relates to a method of synthesizing liquid hydrocarbons and more particularly to a method of converting methane and like light hydrocarbon gases into hydrocarbons suitable for use as a motor fuel. One object of our invention is to provide a ... commercially practicable and economical method of converting methane into liquid hydrocarbons suitable for use as motor fuel. (The) invention contemplates the oxidation of methane to form mixtures of carbon monoxide and hydrogen and the synthesis of the synthesis gas thus formed into liquid hydrocarbons ... (and) only steam and carbon dioxide (need be) employed for converting methane into synthesis gas";
such Coal-based, nearly-pure Methane can be reacted with "steam and carbon dioxide", which Carbon Dioxide could be reclaimed from whatever external source; with both the Methane and the Carbon Dioxide being converted, through that reaction, into a "synthesis gas" which can be catalytically condensed into certain "liquid hydrocarbons", which are "suitable for use as a motor fuel".