Process for the production of carbon monoxide from a solid fuel
We've extensively documented the development of a rather vast body of Coal, and other Carbon resource, conversion technology by the famous, and former, Texaco; which has since been assimilated by, and for all practical purposes disappeared into, the Chevron conglomerate.
We attempt to emphasize the importance of again demonstrating and explaining their expertise in Coal conversion science in comments, with separate links and excerpts appended, but:
Texaco's Carbon resource conversion efforts were founded originally, well more than half a century ago, on the gasification of Coal into a synthesis gas, composed primarily of Hydrogen and Carbon Monoxide, that can be catalytically condensed, as via, for one example, the long-known Fischer-Tropsch process, and be chemically transformed thereby into liquid hydrocarbons.
One early example of their Coal gasification technology can be seen in our report of:
Texaco 1951 Coal + CO2 + H2O + O2 = Syngas | Research & Development; concerning: "United States Patent 2,558,746 - Carbon Monoxide and Other Gases from Carbonaceous Materials; 1951; Assignee: The Texas Company, NYC; Abstract: This invention relates to a process and apparatus for the generation of gases comprising carbon monoxide from carbonaceous materials. In one of its more specific aspects it relates to a process and apparatus for the generation of a mixture of carbon monoxide and hydrogen, suitable as a feed for the synthesis of hydrocarbons, from powdered coal. The synthesis of hydrocarbons by the interaction of carbon monoxide and hydrogen is well known (and, a) number of processes are known to be effective for liquid hydrocarbon synthesis. The present invention is concerned with the generation of a mixture of carbon monoxide and hydrogen (and) is particularly suited to the production of a feed gas for the synthesis of hydrocarbons. (And,) the method and apparatus is especially useful when powdered coal is used as the feed material."
And, some of Texaco's Coal gasification technologies are so efficient, that, as seen in our report of:
Texaco Makes Methane from Coal & "Stuff" | Research & Development; concerning, among others: "United States Patent 3,671,209 - Garbage Disposal Process; 1972; Assignee: Texaco Development Corporation",
such things as plain old, Carbon-recycling "garbage" and "concentrated sewer sludge" can be added to and gasified with Coal; with all of those materials being converted into a gas mixture suitable for the synthesis of both gaseous and liquid hydrocarbons.
As plainly described in the full Disclosure of "United States Patent 2,558,746", some amount of free, molecular Oxygen is required to support the partial oxidation of the Carbon resource, and thus provide the thermal energy needed to drive the associated reactions between the Carbon resource both with Carbon Dioxide, CO2, to form Carbon Monoxide; and, with Steam, H2O, to form both Hydrogen and more Carbon Monoxide.
Our intent in this dispatch is to again confirm that Coal can be reacted with Steam and be made thereby to form a blend of Carbon Monoxide and Hydrogen in proportions well-suited for the chemical synthesis of hydrocarbons; and, to document and emphasize that economical industrial processes exist, and are now being commercially utilized, to provide the needed Oxygen to drive such synthesis gas production processes.
Comment, and additional links and excerpts, follow excerpts from the initial link in this dispatch to:
"United States Patent 2,761,772 - Production of Carbon Monoxide from a Solid Fuel
(Note that the title is somewhat misleading. This is, as will be seen, a process for the production of both Carbon Monoxide and Hydrogen, a complete hydrocarbon synthesis gas, in other words.)
Date: September, 1956
Inventor: Harold Atwell, NY
Assignee: The Texas Company (Texaco), NYC
Abstract: This invention relates to a process for the generation of carbon monoxide from a solid carbonaceous fuel. In one of its more specific aspects, this invention relates to an improved method for the production of a mixture of carbon monoxide and hydrogen from a solid carbonaceous fuel.
The process is particularly applicable to the reaction of powdered coal with oxygen and steam to produce carbon monoxide and hydrogen.
Gasification of coal to carbon monoxide is an industrially important operation.
Coal and related solid fuels may be reacted with a restricted quantity of free oxygen ... to produce carbon monoxide relatively free of carbon dioxide.
(Note the above important fact. Some "free oxygen" is needed, but it's supply can be "restricted" to prevent, or limit, the co-production of CO2.)
The reaction may be carried out with air in which case the product gas contains a relatively high percentage of nitrogen. Because this generally undesirable, oxygen or oxygen-enriched air may be preferred.
(Thus, the justification for separating and concentrating Oxygen for use in the gasification reaction.)
In any case, the reaction, being exothermic, liberates more heat than is required to maintain the desired reaction temperature.
Carbon dioxide or steam may be added to the reaction zone to control the reaction temperature.
Steam (serves) to control the temperature in the reaction zone and at the same time to produce hydrogen.
In accordance with this invention, a portion of the fuel is burned substantially completely, while a further portion is subjected to reaction with the resulting gaseous products of combustion to produce carbon monoxide and hydrogen.
(One of the "gaseous products of combustion" is Carbon Dioxide, which then reacts with a "further portion" of Carbon to form "carbon monoxide". The heat from that initial combustion provides the energy that drives the subsequent "C + CO2 = 2CO" and "C + H2O = CO + H2" reactions.)
Various solid fuels including lignite, anthracite and bituminous coals ... may be subjected to gasification.
Carbon monoxide, hydrogen and mixtures thereof are useful in a number of industrial processes. For example, liquid hydrocarbons suitable for use as motor fuels may be produced by reaction of hydrogen with carbon monoxide in the Fischer-Tropsch type synthesis reaction.
One of the objects of this invention is to provide an improved process for the generation of carbon monoxide and hydrogen from a solid carbonaceous fuel by reaction of oxygen ... . Another object is to provide a process for generation of carbon monoxide and hydrogen in such a system wherein the efficiency of gasification is substantially increased.
In accordance with this invention, solid fuel, for example, coal, is reduced to a particle size smaller than 40 mesh, commercially referred to as powdered coal. Before the powdered coal is subjected to gasification the finest particles are separated therefrom, for example, by screening. The fine particles are fed into the reaction zone into admixture with a stream of oxygen-containing gas in such proportions that are completely burned to carbon dioxide, thus yielding combustion products at a very high temperature.
(It is that "very high temperature" which drives the subsequent endothermic reactions, as following.)
The high temperature stream of gases, comprising carbon dioxide and steam, is (then) brought into contact with the coarser particles of coal under reaction conditions favorable for the production of carbon monoxide and hydrogen.
Contact between the hot carbon dioxide and steam, and the coarser particles of fuel is preferably conducted in a gas generation zone in which a high degree of turbulence is attained."
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We'll close our excerpts there to summarize what Texaco goes on to describe in great and thorough detail:
A first portion of relatively finer Coal is completely and thoroughly combusted with, preferably, purified Oxygen, and some Steam.
The very hot exhaust gases from that combustion are then passed, with, as we read it, the addition of more Steam and a restricted amount of Oxygen, to a second portion of relatively coarser Coal, where the heat from the first combustion drives reactions between both the Carbon Dioxide and the H2O in the exhaust with the Carbon, to form a blend of Carbon Monoxide and Hydrogen, which, as Texaco describes it, is essentially free of Carbon Dioxide; and, thus, is much more reactive and much more amenable to catalytic condensation into more desired hydrocarbons.
Note that this is, thus, a "two-stage" gasification process, similar in concept, if not specific design, to others about which we have previously reported, as in:
Chicago Gasifies Coal, and Recycles CO2 and Carbon for USDOE | Research & Development; concerning: "United States Patent 5,092,984 - Pyrolysis of Coal; 1992; Institute of Gas Technology, Chicago; Abstract: A method for mild gasification of crushed coal in a single vertical elongated reaction vessel providing a fluidized bed reaction zone, a freeboard reaction zone, and an entrained reaction zone within the single vessel. Government Interests: The U.S. Government has a paid-up license in this invention and rights as provided for by the terms of contract No. DE-AC21-87MC24266 awarded by the U.S. Department of Energy.Claims: A process for pyrolysis of coal comprising: separating coal feed particles into a coarse fraction (as specified) and a fines fraction (as specified, and) introducing said coal feed particles into at least two reaction zones."
Further, even more thorough, though still related, complete Coal gasification schemes have been developed, as in:
USDOE Hydrogasifies Coal, Recycles Carbon | Research & Development; concerning: "United States Patent 3,988,123 - Gasification of Carbonaceous Solids; 1976; Assignee: The United States of America;
The invention described herein was made in the course of Contract E(49-18)-1548 with the U.S. Energy Research and Development Administration; Abstract: A process and apparatus for converting coal and other carbonaceous solids (into) a synthesis gas. A stream of entrained pulverized coal is fed into the combustion stage of a three-stage gasifier along with a mixture of oxygen and steam at selected pressure and temperature."
But, we'll also note that other versions of related Coal gasification technology, as seen in:
Exxon Coal + CO2 + H2O Combo Gasification & Conversion | Research & Development; concerning: "United States Patent 4,318,712 - Catalytic Coal Gasification Process; 1982; Exxon Research and Engineering; A process for the catalytic steam gasification of coal. The process ... is one for the gasification of bituminous coal, subbituminous coal, lignite, organic waste materials or similar carbonaceous solids in the presence of added sodium and potassium compounds. It will be understood that the invention ... may be employed in ... gasification operations ... to promote the reaction of steam, hydrogen, carbon dioxide, or a similar gasification agent with (carbon, and, as) a result, the overall cost of the product gas may be substantially reduced";
seem able to do away with the need for an initial, high-temperature combustion, which generates Carbon Dioxide, through the use of catalysts which promote the needed reactions between H2O, CO2 and Coal at much-reduced temperatures.
Other technologies, utilizing "Oxygen donors", as, for just one example, seen in our report of:
Oklahoma Oxygen Donor Coal Gasification | Research & Development; concerning: "United States Patent 4,070,160 - Gasification Process with Zinc Condensation on the Carbon Source; 1978; Phillips Petroleum Company; Abstract: In a process for gasifying solid carbon sources such as coal utilizing zinc oxide as the oxygen donor";
are able to supply Oxygen in restricted amounts to the Coal gasification process through the use of reactive metals, which first extract Oxygen from the atmosphere, to become themselves "oxidized", and, then, transfer that Oxygen to Carbon, in a limited way, so that preferentially more Carbon Monoxide is formed in the heat of a gasification process.
However, we did want to make certain it was understood, that, no matter how it's approached, such complete gasification of Coal - - or any Carbon resource, such as, as in Texaco's above-cited "United States Patent 3,671,209", wherein "garbage" and "sewage sludge" are specifically mentioned - - even if such a gasification does require Oxygen, can be accomplished economically, since long-established industrial processes for the economical separation of gases in plain old air do exist.
And, such technology is being employed, right now, to help convert Coal, at one of the largest industrial complexes in the world, into anything and everything we now derive from petroleum, as told to us by Siemens Aktiengessellschaft (AG), in:
http://www.energy.siemens.com/
"Air Separation:
Our compressors provide the oxygen and nitrogen your processes need. Air separation plants supply oxygen and nitrogen to numerous applications such as ... Coal-to-Liquids (CTL),
The (South Africa Synthetic Oil Limited) Sasol group’s synthetic fuels business is based at Secunda, some 120 km east of Johannesburg. In 1993 its synfuels and petrochemical production facilities were integrated into a single giant production unit and developed to achieve far greater economies of scale. More than ten years on, the development of this massive complex remains the world’s largest engineering project ever undertaken at one time.
(Note: A facility intended to convert Coal into anything, literally anything, we now derive from conventional petroleum sources is now "the world’s largest engineering project ever undertaken at one time". How nice would it be to land a sucker like that in West Virginia? If you think that to be unrealistic, read on.)
(At Sasol's Secunda complex) coal is fed at around 120,000 tonnes per day to the gasification plant where it is converted into crude syngas under high temperature using superheated steam and oxygen in pressurized reactor vessels. The high-purity oxygen is supplied by 15 air separation plants at the astounding rate of 38,550 tonnes of gas per day ... making Sasol the world’s largest single producer and consumer of oxygen. Following the removal of condensates, sulfur and other impurities, the syngas is reacted under pressure and moderate temperature with an iron-based catalyst in a unique one-step process to produce literally hundreds of high-value chemicals—ranging from Acetic acid to Xylenol—simultaneously with synthetic petroleum products at the rate of some 150,000 barrels per day. The major share of the stream is routed to conventional refinery plants to produce liquid petroleum gas (LPG), propane, butane, fuel oil, paraffin, petrol and sulfur-free diesel."
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We'll have more on air separation, and the economical supply and utilization of Oxygen in Coal, and other Carbon resource, conversion technologies in reports to follow.
But, in closing, note:
South Africa, home of the "largest engineering project ever undertaken at one time", which project converts Coal into liquid hydrocarbon fuels and other needed products, has, according to British Petroleum, in:
Coal Mining in South Africa - Overview; "coal reserves of 30408 million tonnes".
West Virginia, has, according to the National Mining Association, in:
http://www.nma.org/pdf/c_
And, South Africa's Secunda Coal conversion complex likely utilizes a technology very similar that developed in the United States of America, more than half a century ago, by Texaco, wherein "liquid hydrocarbons suitable for use as motor fuels may be produced by reaction of hydrogen with carbon monoxide in the Fischer-Tropsch type synthesis reaction", and, wherein that blend of "hydrogen and carbon monoxide" is produced by the "reaction of powdered coal with oxygen and steam".