As seen in one of our earlier reports, as accessible via:
USDOE Hires Exxon to Improve Low-Rank Coal Liquefaction | Research & Development; concerning: "United States Patent 4,304,655 - Liquefaction Process; 1981; Assignee: Exxon Research and Engineering Company; Abstract: Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with a combination of pretreating agents comprising SO2 and an oxidizing agent.Government Interests: The Government of the United States of America has rights in this invention pursuant to Contract No. EF-77-A-01-2893 awarded by the U.S. Department of Energy; This invention relates to an improved process for ... liquefying coal and similar carbonaceous materials";
our United States Government, in it's wisdom, used tax money contributed, in theory, by every United States citizen - - including those United States citizens toiling in the Coal mines of Appalachia who were spending their hard-earned money on OPEC gasoline, in addition to taxes, and, thus, conceptually, buying toe rings for all the Oil sheiks' harem girls just to get to work every day - - to pay Big Oil to figure out how to do a better job of making liquid fuels out of our domestic US Coal.
And, even though Uncle Sam "has" some unspecified "rights" to that tax-funded technology, "B.O." owns it.
That abbreviated nickname seems appropriate to us, since something sure is beginning to smell.
Maybe Uncle Sam needs to spend a few of our tax dollars on some deodorant for him and his apparently good buddies, the next time he goes shopping, especially since his "rights" in that United States Patent didn't, and still don't, apparently, extend to letting the people who paid to have the technology developed even know that such technology had been developed.
In any case, Sam liked the way that deal turned out so much that he turned around and cut another one just like it, so that he could pay B.O. even more of our tax money to figure out how to do an even better job of converting even more of our domestic, low-rank Coal into liquid hydrocarbon fuels.
As should be evident in our excerpts from the initial link in this dispatch to:
"US Patent 4,450,066 - Pretreatment to Prevent Scale During Liquefaction of ... Carbonaceous Materials
Date: May, 1984
Inventors: John Stone and Frank Floyd, Texas
Assignee: Exxon Research and Engineering Company, New Jersey
Abstract: Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by hydrothermal pretreatment. The said pretreatment is believed to convert the scale-forming components to the corresponding carbonate prior to liquefaction. The said pretreatment is accomplished at a total pressure within the range from about 1000 to about 4400 psia. Temperature during said pretreatment will generally be within the range from about 500 to about 700 F.
Government Interests: The Government of the United States of America has rights in this invention pursuant to Contract No. DE-FC01-77ET10069 (formerly Contract No. EF-77-A-01-2893) awarded by the U.S. Energy Research and Development Administration, now the U.S. Department of Energy.
(The business deal formerly known as "Contract No. EF-77-A-01-2893", by the way, is the one which led to our previously-reported, above-referenced "United States Patent 4,304,655".)
Claims: A process for the liquefaction of a lower ranking coal or similar solid carbonaceous material containing (a specified amount of) moisture consisting essentially of the steps of: hydrothermally pretreating said coal or carbonaceous material by heating the coal or solid carbonaceous material to a temperature within the range from about 500 to about 700 F at a total pressure at least 10% above the vapor pressure of water at the pretreating temperature to reduce the amount of alkaline earth metal humates therein;
(and) liquefying the thus treated coal at liquefaction conditions to produce a petroleum-like product.
The process ... wherein the coal or similar carbonaceous material is combined with a solvent and heated for a period of time within the range from about 15 to about 120 minutes during the hydrothermal pretreatment.
The method ... wherein the liquefaction is accomplished in the presence of a hydrogen donor solvent (and) in the presence of added molecular hydrogen.
(As far as "hydrogen donor solvent"s go, see, for example:
WVU Hydrogenates Coal Tar | Research & Development; concerning: "Hydrogenation of Naphthalene and Coal Tar Distillate; Abhijit Bhagavatula; West Virginia University; 2009; The hydrogenation of naphthalene and coal-tar distillates has been carried out in a Trickle Bed Reactor. The operating conditions employed for the hydrogenation of naphthalene (were varied, and the results monitored, and a) unique peak for naphthalene was observed ... (as was) the peak for the hydrogenated product, tetralin ... (for use in the) the conversion of coal to refinable crude hydrocarbons, from which liquid fuels such as gasoline, diesel, kerosene, etc., can be produced"; and:
Exxon 1982 CoalTL Uses WVU CoalTL Hydrogen Donor Solvent | Research & Development; concerning: "United States Patent 4,345,989 - Catalytic Hydrogen-donor Liquefaction Process; 1982; Exxon Research and Engineering Company, NJ; Abstract: Coal or a similar solid carbonaceous feed material is converted into lower molecular weight liquid hydrocarbons by contacting the feed material with a hydrogen-donor solvent. Tetralin (is) an extremely good hydrogen-donor solvent".
And, since free, molecular Hydrogen is required both to hydrogenate the "hydrogen donor solvent", and then during "the liquefaction" of Coal with that solvent, keep in mind that, as, for just a few examples, in:
Consol 1953 Coal to Hydrogen & Methane with No CO2 | Research & Development; concerning: "United States Patent 2,654,661 - Gasification of Carbonaceous Solid Fuels; 1953; Consolidation Coal Company, Pittsburgh; This invention relates to the gasification of carbonaceous solid fuels, and particularly to the production of hydrogen or high B.t.u. gas from such fuels. A gaseous product is obtained which contains methane and hydrogen in varying relative proportions depending upon the particular temperature and pressure conditions"; and, in:
Pittsburgh Hydrogen for Coal Liquefaction | Research & Development; concerning: "United States Patent 3,888,750 - Electrolytic Decomposition of Water; 1975; Westinghouse Electric Corporation, Pittsburgh; Electrolysis and catalytic thermochemistry are combined to decompose water while minimizing the energy demanded to accomplish the decomposition";
some advantageous technologies are available to provide any Hydrogen which might be needed.)
Background and Field: This invention relates to an improved process for converting coal or similar solid carbonaceous material containing certain mineral matter. More particularly, this invention relates to an improved process for liquefying coal and similar carbonaceous materials.
As is well known ... petroleum and gas reserves are shrinking throughout the world and the need for alternate sources of energy is becoming more and more apparent. One such alternate source is, of course, coal since coal is an abundant fossil fuel in many countries throughout the world.
(And,) several processes wherein coal is either liquefied and/or gasified have been proposed heretofore. Of these, the processes wherein coal is liquefied appear to be more desirable in most cases since a broader range of products is produced and these products are more readily transported and stored. Difficulty has, however, been encountered during the liquefaction of certain coals, particularly the lower ranking coals, and apparently as the result of extraneous mineral matter contained in these coals.
While the inventors here do not wish to be bound by any particular theory, it is believed that the operating difficulties are associated with the presence of one or more alkaline earth metals, particularly calcium, and to some extent the presence of iron, which react during liquefaction with available anions to form a solid scale or deposit. A large portion of the scale remains in the liquefaction reactor thereby reducing reactor volume, and hence, the liquefaction contacting time and/or the total throughput. Ultimately, complete plugging may occur. Moreover, a portion of the scale or deposit remains in the liquid product and has resulted in downstream plugging.
The scaling and/or deposit problem is believed to have been first reported upon in the literature in connection with the operation of a high pressure coal liquefaction plant for producing liquids from lignites at Wesseling, near Cologne, Germany. According to the literature, operation of this plant was severely limited by a solid referred to as "caviar", the reference apparently stemming from the appearance of the solid in the form of agglomerated balls or spherulites. According to the literature, the spherulites were found to comprise calcium carbonate and hexagonal crystals of iron sulfide.
(Recently), it has been discovered that calcium carbonate deposits which form during liquefaction as the result of the decomposition of various calcium organic compounds can be avoided by converting the calcium organic compounds, which do decompose during liquefaction, to a salt which will remain stable during liquefaction or to a form which can be removed prior to liquefaction. Conversions of this type can be effected with a relatively broad range of pre-treating agents including salts of metals different from calcium which will, effectively, replace the calcium in the coal, various organic and inorganic acids and certain gaseous pre-treating agents such as SO2 and SO3.
Carbonic acid is included among the list of known pre-treating agents.
(The above "Carbonic acid", by the way, could be made by dissolving Carbon Dioxide in water.)
For the most part, these ion exchange-type pretreatments have been quite effective in solving the scale or deposition problem. Most such treatments, however, involve the use of aqueous solutions of pre-treating agents thereby increasing the amount of water which must be removed either prior to or during liquefaction. Moreover, many of these pretreatments increase the amount of ash or residue which must ultimately be disposed of and/or involve the use of pre-treating agents which are known pollutants and therefore which must be separated from any gas stream ultimately vented to the atmosphere and some of which are hazardous in their own right. The need, therefore, for an improved method of avoiding the scale and/or solid deposition problem is believed to be readily apparent.
Summary: It has now, surprisingly, been discovered that the foregoing disadvantages of the prior art pretreatment methods can be overcome with the method of the present invention and a method for more effectively liquefying lower ranking coals provided thereby. It is, therefore, an object of this invention to provide an improved method for liquefying lower ranking coals and similar carbonaceous materials containing organic salts of alkali metals which decompose during liquefaction to produce a scale and/or solid deposit which hampers smooth operation. It is still another object of this invention to provide such an improved process wherein the scale and/or solid deposition problem is avoided by pretreatment of the coal or similar carbonaceous material to be liquefied in a manner which does not require the use of added water. It is still another object of this invention to provide such an improved process wherein the pretreatment is accomplished in a manner which does not require the use of a pre-treating agent and hence which does not require the use of such an agent which is a pollutant or which is hazardous to use. It is yet another object of this invention to provide such an improved process wherein the pretreatment is accomplished with a pre-treating agent which does not result in an increase in the amount of residue which will ultimately be discarded.
In general, the improved method of this invention can be used with any coal containing one or more alkaline earth metal humates and particularly any coal containing calcium humate.
Following the pretreatment, the coal may then be liquefied by any of the methods known in the prior art to be effective therefore. Such methods include processes wherein the coal is simply subjected to pyrolysis in the absence of air or oxygen, processes of the type where the coal is heated in the presence of hydrogen and processes wherein coal is liquefied in the presence of a solvent.
In general, the pretreatment of the present invention can be effected simply by heating the coal, preferably in a finely divided state, to a temperature within the range from about 500 to about 700 F. at a total pressure within the range from about 1000 to about 4400 psi and holding the coal or other carbonaceous material at these conditions for a period within the range from about 15 to about 120 minutes. Best results will, however, be obtained when the finely divided coal is combined with a hydrocarbon solvent and preferably the solvent to be used during the subsequent liquefaction. Moreover, while the finely divided coal may be combined with the solvent in essentially any ratio, or at essentially any concentration, best results will, generally, be achieved when the coal is combined with the solvent at the same ratio as that employed during the subsequent liquefaction.
It is important that the coal be subjected to a hydrothermal treatment in accordance with the present invention and contain between about 20 and 40% moisture and that the hydrothermal treatment be effected at a total pressure sufficient to retain at least a portion of this moisture in the liquid state during the treatment."
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It's pretty straightforward, really: All that needs done is to grind the Coal; make sure it's mixed with sufficient Water, in amounts specified by Exxon; add a little Hydrogen-donor solvent for spice - which solvent is, in the first place, made from Coal tar; and, then, stew the mix for up to two hours in a pressure cooker.
Truth to tell, the pressure capacities required of the pretreatment stew pots, in combination with the sizes needed to accomplish the pretreatment and subsequent conversion of meaningful quantities of low-rank Coal, would present some engineering challenges.
But, we assure you:
All of the pressures and temperatures specified herein by Exxon, applied to reaction vessels of sizes significant enough to be meaningful in terms of low-rank Coal conversion, are well within the realm of current chemical engineering experience and commercial industrial practice.
The only real drawback would be in the initial capital investment needed to fabricate reaction vessels of the capacities needed.
But, that capital investment could, and should, be paid to American steel workers, so that they can make the equipment needed to process the material provided by American Coal miners, so that all American citizens can tell OPEC to take their Oil and shove it.
The entertainment value of that, alone, should be well-worth the investment price of admission.