http://www.anl.gov/PCS/acsfuel/preprint%20archive/Files/40_1_ANAHEIM_04-95_0124.pdf
We have many times in our posts documented the expertise of the Eastman Chemical and Air Products companies in the technologies of Coal conversion into value-added products, most especially into the gasoline, as in ExxonMobil's "MTG"(r) - methanol-to-gasoline - Process, raw material, Methanol.
That, especially as reduced to industrial practice in Eastman's Kingsport, TN, Coal-to-Methanol industrial production facility.
Herein, via the above link and attached document, is a fuller description of their technology, with excerpts and comment following:
COMMERCIAL-SCALE DEMONSTRATION OF A LIQUID-PHASE METHANOL PROCESS
Steven L. Cook; Eastman Chemical Company; Kingsport,TN 37662
Abstract: The Eastman Chemical Company operates a coal gasification complex in Kingsport. Tennessee.
The primary output of this plant is carbonylation-derived acetic anhydride. The required methyl acetate is made from methanol and acetic acid. Methanol is currently produced from syngas ... .
(Syngas made from Coal.)
A liquid-phase methanol process (LPMEOHIM) has been developed by Air Products. Efficient heat removal permits the direct use of syngas without the need for the shift reactor. An Air Products/Eastman joint venture, with partial funding from the Department of Energy under the Clean Coal Technology Program, has been formed to build a demonstration-scale liquid-phase methanol plant. This talk will focus on the unique features of this plant and how it will be
integrated into the existing facilities.
Eastman Chemical Company has practiced the carbonylation of methyl acetate to acetic anhydride for many years.In an array of integrated plants, coal is gasified and the resulting synthesis gas purified to a high degree. This gas, which consists chiefly of carbon monoxide and hydrogen, is used to feed the chemical plants. Methanol is produced in one plant by the Lurgi low-pressure gas-phase process.
The syngas needed for these plants is produced by two high-pressure gasifiers. High-sulfur coal is ground and fed to these gasifiers as a water slurry with pure oxygen. The hot gas is scrubbed with water to reduce the temperature and remove ash. A portion of the crude syngas is routed to a water-gas shift reactor to enrich the stream in hydrogen so that the stoichiometry required for methanol synthesis can be attained. Hydrogen sulfide is then scrubbed from the gas streams and converted to elemental sulfur.
(As we have earlier documented, the by-product Sulfur has commercial value. Importantly: The Sulfur is removed, and the resulting Methanol, liquid fuel, would be virtually Sulfur-free.)
In a methanol plant, the reaction between carbon monoxide, carbon dioxide, and hydrogen is exothermic and, because of the fixed bed reactor design, heat control and removal is of prime concern.
(Again as we have documented: Some of the process steps in indirect Coal conversion processes are exothermic, and the heat generated could be recovered, reclaimed, and used to help drive the overall process; as explained following.)
For a given catalyst, a liquid-phase reactor is preferable for numerous reasons. The basic characteristics of a liquid-phase reactor allow it to be cooled internally. This is a significant advantage for removing the rather large net heat of reaction encountered during methanol synthesis. By removing this heat with an internal heat exchanger, steam can be co-generated and employed for various process uses.
... benefits resulting from (the Eastman/Air Products) configuration are that the H2/CO/C02 stoichiometry need not be controlled as closely ... and carbon dioxide can be present in high concentrations.
(As we've previously documented: Perhaps additional Carbon Dioxide could be added.)
The net result ... is that the expense and added complexity of a shift reactor can be eliminated because, in most cases, syngas can be used directly.
(Coal-derived "syngas can be used directly" without additional costs for purification or concentration.)
The liquid-phase methanol process developed by Air Products and Chemicals, Incorporated, offers a sound way to take advantage of the benefits of internal heat removal. ... this process allows purified but otherwise unaltered synthesis gas to be fed directly to the reactor. The copper/zinc oxide-based methanol catalyst is suspended in an inert oil, which serves as the heat transfer medium. Internal heat exchangers remove the heat generated by the highly exothermic reaction and provide process steam for appropriate uses.
An Air Products/Eastman joint venture, with partial funding from the Department of Energy under the Clean Coal Technology Program, has been formed to build a demonstration-scale version of liquid-phase methanol plant. ... The gasification complex in Kingsport, Tennessee provides an ideal source of synthesis gas to test this plant. In addition to providing methanol ... (it will) ... be possible to ramp the output up and down, co-produce dimethyl ether (DME), and produce fuel-grade methanol for testing in on- and off-site applications, such as power plant boilers, buses, and vans.
(What about plain old automobiles? As we've earlier reported, dimethyl ether, DME, is a valuable, clean, almost direct substitute for diesel fuel.)
A brief description of the overall operation...: Coal is systematically unloaded from rail cars and continuously fed to grinding mills by a highly automated Coal Handling system. In the Coal Slurry section, coal is mixed with water during the grinding process to provide a mobile slurry that can be pumped to the gasifiers. Oxygen is provided by an Air Products separation plant. Use of pure oxygen allows the gasifiers to operate at over IOOO'C, which eliminates the coproduction of environmentally undesirable byproducts.
Within the Gasification Plant the coal slurry and oxygen combine in Texaco-designed gasifiers in a sustained reaction to produce a CO-rich product.
(We have earlier documented Texaco's expertise in the art of Coal gasification.)
The crude gas is then passed through a water-gas shift reactor to increase the hydrogen content. Before exiting the gasification plant, the product gas is cooled by water-fed heat exchangers that produce low-pressure process steam for use elsewhere in the complex.
Within the Gas Purification section Hydrogen Sulfide and Carbon Dioxide are removed by the Linde AG-developed Rectisol process.
(We have earlier documented the Linde Rectisol process for more efficient CO2 recovery which might enable the use of recovered CO2 in Sabatier-type, follow-on processes for the co-production of Methane.)
This is accomplished by selectively absorbing the gases in cold methanol. The hydrogen sulfide-carbon dioxide stream is sent to the Sulfur Recovery plant where a Claus unit, coupled with a Shell off-gas treating unit, converts it to elemental sulfur. This sulfur is clean enough to be sold as a pure byproduct.
The final off-gas consists mainly of carbon dioxide, which is converted to the solid form for various commercial uses.
(Again, if they can extract a gas that's mainly CO2, so pure it can be converted to, essentially, "dry ice", it could instead be recycled, via the Sabatier, and similar, processes, into additional hydrocarbons.)
As the syngas exits the purification section, a portion of it is passed to CO-Hydrogen Separation, essentially a cryogenic "cold box" (also developed by Linde) which permits separation of carbon monoxide and hydrogen by low-temperature distillation. The hydrogen from this unit is combined with (product) from the Gas Purification section to serve as feed for the Methanol Plant.
It is well known that the presence of CO2 is essential to optimal operation of copper/zinc oxide-based methanol reactors. It is critical for conditioning and preventing damage to the catalyst.
(There's a kicker, ain't it: "It is well known that the presence of CO2 is essential". We need the stuff.)
Again, because of the heat management capabilities of the LPMEOP process, the amount of carbon dioxide normally present in raw syngas can be used without concern for overheating the catalyst. This results in a much more efficient use of carbon in the syngas.
The construction and successful operation of the LPMEOHm plant will be a landmark in development of synthesis gas technology. Given the importance of methanol not only as a chemical feedstock but as a fuel, demonstration of this technology on a commercial scale could have far-reaching importance. We at Eastman are pleased to be a part of this effort."
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Well, it seems nearly all of us in US Coal Country somehow missed this "landmark in development of synthesis gas technology", and have, since then, badly lost our way.