A potential economic benefit of Coal liquefaction which might not readily leap to mind is revealed in the Chevron technology we report in this dispatch.
As with natural deposits of crude petroleum, commercially-significant beds of Coal aren't always close to established routes of transport, and mine sites can thus be remote from "the market".
Transport costs, even if suitable transportation routes are available, could thus be so excessive that mining the Coal, for any purpose, would be uneconomical.
That issue has been addressed by others previously, and one solution that has been proposed to lower the costs of Coal transport - though we haven't researched to find out if it has anywhere been reduced to genuine commercial practice - is to grind Coal up at the mine site, blend it into water, and then pump the resulting "slurry", via pipeline, for delivery to the end-use or refining and processing locations.
One famed petroleum industry example relating, or analogous, to that concept would be the Alaska Pipeline.
Herein, we see that Chevron takes the Coal slurry transport concept, as a means of reducing energy transportation costs, one step further:
They propose converting Coal at the mine site into a crude petroleum-like liquid, and piping that "syncrude" to places of further refining, nearer the marketplace, for separation into liquid fuel and lubricating oil.
Some advance excerpts might help to clarify that intent, which is otherwise somewhat obfuscated by the way the full Disclosure is structured, as in:
"In the process, a carbonaceous source which is recovered from a remote site is converted through a series of steps into a stabilized product mixture at or near the remote site. At least a portion of stabilized product mixture is then exported to a market location, for a final separation step to produce at least one finished fuel product.
More specifically, in the present process, a carbonaceous source, such as ... coal is recovered ... at a remote site (and) converted to a syngas comprising predominantly H2 and CO. The syngas is further converted to synthetic hydrocarbons in a hydrocarbon synthesis process, and the synthetic hydrocarbon products so produced are converted to a stabilized product mixture for export to a market location.
A Fischer-Tropsch synthesis process is the preferred process for preparing the synthetic hydrocarbons.
In the preparation of the stabilized product mixture, the synthetic hydrocarbon product is upgraded via hydroprocessing, at conditions selected to yield a stabilized product mixture which comprises fuel and/or lubricating oil base stock range products. At least one of the products present in the stabilized product mixture has the properties of a finished fuel product, and can be recovered as such by an additional distillation step."
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That "distillation step" would take place at or near "a market location"; and, both a "finished fuel product", specified by Chevron in the full disclosure to be Diesel, and "lubricating oil" are thereby extracted from the mix of Coal liquefaction products.
The concept has implications we attempt to highlight and clarify, following more complete, excerpts from:
"United States Patent 6,635,681 - Fuel Production from Fischer-Tropsch Process
Date: October, 2003
Inventor: Richard Moore, CA, and Mark Schnell, UK
Assignee: Chevron USA, CA
Abstract: A process is disclosed for preparing a finished fuel product from a stabilized product mixture, which is produced from the effluent of a Fischer-Tropsch synthesis process. In the process, a Fischer-Tropsch synthesis process is conducted at a site which is remote from the market site where the products from the process are ultimately marketed. The Fischer-Tropsch effluent product is hydroprocessed, and the hydroprocessed ... to yield a stabilized product mixture which can be exported to the market site.
At the market site, the stabilized product mixture is fractionated into at least one finished fuel product.
A heavy fraction may also be recovered at the market site for separation into at least one lubricating oil base stock and then conversion ... to form a lubricating base oil.
Claims: A method for preparing finished products from a Fischer-Tropsch synthesis process, the method comprising: a) reacting a synthesis gas comprising H2 and CO to form at least one Fischer-Tropsch effluent product at a remote site; reacting at least a portion of the Fischer-Tropsch effluent product at hydroprocessing conditions to form a hydroprocessed effluent at the remote site; ... (and) transporting at least a portion of the stabilized product mixture to a market site; and separating at least a portion of the stabilized product mixture at the market site into at least one finished fuel product.
(And) wherein the at least one finished fuel product is a diesel fuel.
(And) wherein the heavy fraction is ... separated (and) converted (into) a lubricating base oil.
Description and Summary: The present invention is directed to a method for preparing liquid fuel in a hydrocarbon synthesis process, and more specifically for preparing a stabilized mixed fuel from a carbon source at a remote site.
In the conventional synthesis process ... coal ... is generally converted to liquid hydrocarbons at a site adjacent to the natural resource. In the Fischer-Tropsch process, a carbon-based resource is converted to syngas (predominantly CO and H2) and the syngas converted to a primarily paraffinic hydrocarbon product.
However, the conventional method has several disadvantages. For one, the conventional processes are complex and expensive, with multiple processing steps conducted at the remote site. Developing the site and transporting equipment to the site is generally more costly that using existing processes at a more developed market site.
Methods for transporting Fischer-Tropsch derived syncrude from a remote site to a commercial refinery are known ... . One approach has been to isolate a C20-36 syncrude and ship this composition as a solid. A limitation of this approach is that it is difficult and expensive to transport solids, because it requires expensive forming, loading and unloading facilities.
(As with Coal. )
Other approaches have focused on transporting syncrude, or a syncrude which has been partially refined to convert some of the linear hydrocarbons into isoparaffins and thus generate a syncrude which is liquid at near ambient temperature.
However, (the necessary processing) may require the construction of facilities which are expensive and difficult to operate in remote locations.
What is needed is a process for preparing a finished fuel from a remote hydrocarbon synthesis process, while reducing the processing complexity of the process at the remote site.
The present invention relates to a Fischer-Tropsch synthesis process, and to an integrated process for preparing a stabilized product mixture, in a Fischer-Tropsch synthesis process, for export to a market location. In the process, a carbonaceous source which is recovered from a remote site is converted through a series of steps into a stabilized product mixture at or near the remote site. At least a portion of stabilized product mixture is then exported to a market location, for a final separation step to produce at least one finished fuel product.
More specifically, in the present process ... coal ... (which) is recovered as a resource at a remote site, is converted to a syngas comprising predominantly H2 and CO.
The syngas is further converted to synthetic hydrocarbons in a hydrocarbon synthesis process, and the synthetic hydrocarbon product so produced are converted to a stabilized product mixture for export to a market location.
A Fischer-Tropsch synthesis process is the preferred process for preparing the synthetic hydrocarbons.
(For) example ..., a carbonaceous material is converted to a syngas comprising CO and H2. Typical reforming methods for preparing CO and H2 from this material include steam reforming, partial oxidation, (etc.). Such processes are well known in the art.
The syngas is reacted in a Fischer-Tropsch reaction zone to produce a light stream ... and a wax stream.
The wax stream and/or the light stream may be processed in a number of alternative ways to produce the stabilized liquid mixture ... which is suitable for transporting from the remote site to a market site for fractionation to prepare finished fuel products."
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That is the sum of it.
We find it roughly similar in concept to some other mine-site CoalTL proposals we first reported to you a few years ago, wherein smaller, somewhat "portable", Fischer-Tropsch processors of modular construction could be manufactured and moved from site to site, where they would recover hydrocarbon values from Coal mine waste accumulations which still contained appreciable amounts of recoverable Carbon.
Older mine sites, especially those where metallurgical-grade Coal was the final product, frequently have waste pile accumulations that contain significant quantities of lower-grade Coals, which were separated from the metallurgical Coal that was shipped on to market.
And, Chevron's invention herein could, thus, relate to proposals like the Schuykill, Pennsylvania, mine waste processor, about which we've reported and which was intended to convert carbon wastes accumulated around old anthracite mines into more-easily transportable, and much more valuable, liquid hydrocarbons.
In any case, this Chevron invention, in one aspect, is focused on improving the total cost of Coal-derived liquids, by reducing the raw material transportation costs that would be rolled into the price of the "finished fuel products" made from Coal, since, in "the conventional synthesis process" wherein "coal ... is generally converted to liquid hydrocarbons at a site adjacent to" the Coal mine, the products have to be shipped from a sometimes "remote site".
Much of the savings arises from the fact that multiple CoalTL products, such as the Diesel fuel and lubricating oils specifically mentioned by Chevron, if refined at the mine site, would have to then be shipped to market separately, and via product-dedicated carriers. Chevron makes the process more economical by proposing that Coal be first converted into a crude, mixed liquid, which can then be transported via a consolidated carrier, in way less expensive than transporting solid Coal or individual liquid hydrocarbon products, to a central place better-situated, relative to the end-use markets, for final refining.
In essence, the Chevron technology reduces the cost of conveying energy to the market; though it also reduces capital cost since the "syncrude" would, presumably, be piped to already-existing petroleum refineries, thus eliminating the expense of building new large-scale refineries dedicated to Coal processing.