We have documented to, we're certain, the point of tedium the multitudinous Coal liquefaction and conversion technologies that were developed, over multiple decades, by the various companies which at last coalesced into that lovable giant, ExxonMobil.
But, herein is yet another; albeit one with a delightful twist for those who object that CoalTL is too costly.
Esso themselves say that all the improvements in Coal liquefaction science they disclose and catalog herein "make the economics of the process appear attractive".
Moreover, as you will see via an additional reference appended, their improvements also likely prevent the release of any Carbon Dioxide.
And, as we point out in our excerpts, with comment inserted and appended, Esso makes Coal conversion "economics ... attractive" by combining and coordinating Coal liquefaction technologies closely related to somewhat dissimilar Coal conversion technologies that had been, and have since been, developed, separately, by the US Bureau of Mines and West Virginia University:
"United States Patent 3,841,991 - Coal Conversion Process
Date: October, 1974
Inventors: Saul Cohen, NJ, and Jack Hochman, UK
Assignee: Esso Research and Engineering Company
Abstract: A process for the preparation of liquid products from coal wherein finely-divided coal particles are slurried in a hydrogen-rich liquid hydrocarbon solvent at low temperature and substantially atmospheric pressure and the resulting slurry is passed into a fluid bed coking unit where conversion of the coal, solids separation, and thermal cracking of a heavy product take place simultaneously.
Background: This invention relates to the manufacture of liquid hydrocarbons from coal and is particularly concerned with an improved coal conversion process wherein conversion of coal, separation of solvent, and thermal cracking of heavy products are carried out simultaneously in a fluidized coking unit.
Prior Art: There is substantial interest in the development of processes for the manufacture of synthetic crude oils and liquid hydrocarbons from coal.
Among the more promising processes of this type are those based upon the solvent extraction of liquid constituents from coal with an aromatic solvent. Such processes require that coal be digested at elevated temperature and pressure with a hydrogen-donor solvent, generally in the presence of added hydrogen gas.
The hydrogen contributed by the solvent and gas increases the amount of extract recovered and upgrades the liquid products.
Following this solvent treatment, the products are separated to yield a high boiling extract containing liquid hydrocarbons and a solid phase composed of insoluble coal residues.
The extract is then subjected to catalytic cracking or other refining processes for conversion of the high boiling material into lower boiling hydrocarbons.
The solids separated from the extract are generally subjected to a low temperature carbonization treatment for the production of additional liquid products and char useful as fuel.
(Without citation, we remind you that, as we long ago reported, such "low temperature carbonization", or "LTC", for Coal conversion into various liquid and gaseous products, is a nearly-ancient Coal processing technology, that was further refined - and then reduced in some places to practice - in the 1920's, through the efforts of US Bureau of Mines scientist, Lewis Karrick, for whom the process is now better-known, if it is known at all, as "The Karrick LTC" process. Following our excerpts from the initial link in this dispatch, we append an additional link, with excerpts, offering more information concerning it.)
The process of the invention has numerous advantages over conventional coal liquefaction processes in that coal conversion, solids separation, and thermal cracking of heavy liquids produced from coal all take place within the coking unit reactor and hence separate liquefaction, solids separation and coking or carbonization units are not required.
This permits savings in plant investment and operating costs.
It also results in much better heat integration than can be obtained in conventional processes (and) permits generation of all of the (needed) process heat from coal without the use of complex coal-fired furnaces.
(And, thus, we submit, without the generation of additional co-product Carbon Dioxide.)
Moreover, it has been found that the yields obtained in the process of the invention compare favorably with those obtained in other coal conversion processes which require extraction of the coal with an aromatic solvent and that the molecular hydrogen which is generally needed to provide reasonable conversion levels in the liquefaction zone of conventional processes is not necessary.
These and other advantages, coupled with the savings in plant investment and operating costs, make the economics of the process appear attractive.
(Initially, an) aromatic hydrogen-donor solvent is introduced into (a) slurry preparation vessel simultaneously with the coal.
The solvent employed will normally be a coal-derived liquid ... .
(Once again, a "coal-derived liquid", taken from the process itself, is specified to be a suitable hydrogenating solvent for liquefying raw Coal.)
Other hydrogen-rich solvents may be used in lieu of or in addition to such a coal-derived liquid ... .
Suitable aromatic hydrogen-donor solvents include hydrogenated creosote oil ... and other coal-derived liquids which are rich in Indane, Tetralin, Decalin ... and similar donor compounds.
(Note that "Tetralin", as above, is, as we have many times reported and documented, an hydrogenated version of the primary Coal oil, Naphthalene; and is also, we believe, the Hydrogen donor solvent specified by WVU, in their "West Virginia Process" for the direct liquefaction of Coal.)
The solvent-coal slurry prepared as described ... is mixed with a high boiling bottoms stream.
(Again: The still-carbonaceous residues, CoalTL "resids", resulting from an initial Coal conversion reaction, be themselves further treated for the extraction of additional hydrocarbon values. In this case, as in one or two others we have previously reported, they are simply blended back into the initial Coal-Coal Oil slurry. We suspect, though, that prior to such recycle blending, some process for the removal of insoluble inorganic components in the residues would have to be employed; otherwise, it would seem that such material might accumulate, to bad effect, within the system.)
Claims: A process for the preparation of liquid products from coal ... ."
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The full Disclosure is fairly lengthy, and presents more technical details of the process than are indicated in our excerpts.
Esso includes all of those technical detailsl, we concluded upon study, simply to support beyond doubt that, by using the process disclosed herein, they could, in fact, prepare "liquid products from coal" with "savings in plant investment and operating costs" that, all the way back in 1974, "make the economics ... attractive".
PS: For those who might be interested in the "Karrick" Low-Temperature Carbonization, "LTC Process, as noted above, in addition to our earlier reports of it's use, as available on the West Virginia Coal Association's R&D web site, following is a link to a decent exposition of it, as made available to us all by the Wikipedia:
Karrick process - Wikipedia, the free encyclopedia
"The Karrick process was invented by Lewis Cass Karrick in the 1920s. Although Karrick did not invent coal LTC as such, he perfected the existing technologies resulting the Karrick process.
The Karrick process is a low-temperature carbonization process, which uses a hermetic retort. For commercial scale production, a retort about 3 feet (0.91 m) in diameter and 20 feet (6.1 m) high would be used. The process of carbonization would last about 3 hours.
Superheated steam is injected continuously into the top of retort filled by coal. At first, in contact with cool coal, the steam condenses to water acting as a cleaning agent. While temperature of coal rises, the destructive distillation starts.
Coal is heated ... in the absence of air. The carbonization temperature is lower compared with (that) for producing metallurgic coke. The lower temperature optimizes the production of coal tars richer in lighter hydrocarbons than normal coal tar, and therefore it is suitable for processing into fuels.
Resulting water, oil and coal tar, and syngas moves out from retort through outlet valves at the bottom of the retort. The residue (char or semi-coke) remains in the retort."
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Such "residue" we remind you, would be similar to that produced in the very similar "COED" Coal conversion process operated for a time by the FMC Corporation for our US Government, at a pilot plant in New Jersey.
In that operation, as we have previously documented, carbonaceous residues left by that process were themselves further processed, using both direct liquefaction with a Hydrogen donor solvent and by gasification with Steam, to produce additional liquid and gaseous hydrocarbons.
Finally, the Wikipedia makes one, perhaps important, last point concerning low-temperature carbonization of Coal:
"The Karrick LTC process generates no carbon dioxide."