United States Patent: 4364915
Herein, we submit a technology that was developed specifically for the efficient and economical recovery of Carbon Dioxide from industrial flue gas, so that the recovered Carbon Dioxide could be subsequently utilized in the synthesis of hydrocarbons.
It has been, in fact, cited as a source of Carbon Dioxide by some very recent expositions of CO2-recycling technology, as for instance can be discovered in our report of:
West Virginia Coal Association | California July 2012 Efficient CO2 to Methanol | Research & Development; concerning: "United States Patent 8,212,088 - Efficient and Selective Chemical Recycling of Carbon Dioxide to Methanol, Dimethyl Ether and Derived Products; Date: July 3, 2012; Inventors: George Olah and G.K. Surya Prakash; Assignee: University of Southern California; Abstract: An efficient and environmentally beneficial method of recycling and producing methanol from varied sources of carbon dioxide including flue gases of fossil fuel burning powerplants, industrial exhaust gases or the atmosphere itself. Converting carbon dioxide by chemical or electrochemical reduction secondary treatment to produce essentially methanol, dimethyl ether and derived products".
Nobel Laureate George Olah consistently cites the technology disclosed herein in many of his and his USC colleagues' patents on their suite of Carbon Dioxide recycling technologies; which, as you know if you have followed our posts thus far, is extensive.
Further, this technology was actually developed to provide Carbon Dioxide, extracted from industrial flue gas, to a conceptually related, but much earlier, CO2-recycling hydrocarbon synthesis process.
As we explain, following excerpts, with comment inserted, from the initial link in this dispatch to:
"United States Patent 4,364,915 - Process for Recovery of Carbon Dioxide from Flue Gas
Process for recovery of carbon dioxide from flue gas - Procon International Inc.
Date: December, 1982
Inventor: Russell Parker, Texas
Assignee: Procon International, Inc., Illinois
(Yes, we know, you've never heard of "Procon International". We won't document their history through links, so you'll have to take our word for it; but, at the time this patent was issued, Procon were a subsidiary of Universal Oil Products, aka UOP, as in our report of:
West Virginia Coal Association | Chicago 1945 Coal to High-Octane Gasoline | Research & Development; "United States Patent 2,377,728 - Hydrogenation of Hydrocarbonaceous Materials; 1945; Assignee: Universal Oil Products, Chicago; Abstract: This invention relates to the production of valuable liquid products including high antiknock motor fuel from coal";
which at some point merged with Honeywell, as indicated in:
West Virginia Coal Association | Honeywell to Convert Coal & Biomass | Research & Development; concerning, in part, the fact that: "UOP LLC, a Honeywell company, announced ... that it has expanded its alliance with Rentech, Inc. to support clean fuels production, adding UOP gas processing technology for the treatment of synthesis gas, or syngas, from ... coal".
And, as Procon, as we'll document after these excerpts, they have worked with some other industry heavyweights on what appear to be government-funded development projects. They are credible.)
Abstract: A process for the recovery of carbon dioxide from a flue gas stream containing residual oxygen is disclosed. A combustible fuel, such as methane, is admixed with the flue gas stream and the flue gas stream is then passed into a combustion zone in which it may be contacted with a catalyst which promotes the consumption of the residual oxygen in a combustion reaction. Preferably, the heat liberated in the combustion reaction is recovered for use in heating flue gas to combustion supporting conditions and in downstream carbon dioxide recovery steps. The purpose of the combustion reaction is to lower the oxygen content of the flue gas stream, which is then contacted with a lean carbon dioxide absorbing amine solution. The low oxygen content reduces the degradation of the amine solution and the corrosiveness of the amine solution thus allowing the use of high strength amine solutions and very high absorbent liquid loadings.
(Don't be discouraged by the seeming waste of "methane", as above; there are other options, as will become clear further on.)
References: United States Patent 3,820,965 - June, 1974
(Quite a few other patents, as is standard practice, are directly referenced by the inventor. The one we include above is of special interest to us, as we will elaborate, following excerpts from our subject, "United States Patent 4,364,915 - Process for Recovery of Carbon Dioxide from Flue Gas".)
Claims: A process for recovering carbon dioxide from a flue gas stream which comprises the steps of:
(a) admixing a combustible fuel into a flue gas stream;
(b) passing the flue gas stream through a combustion zone in which the combustible fuel is reacted with oxygen originally present in the flue gas stream;
(c) cooling the flue gas stream;
(d) contacting the flue gas stream with a lean absorber liquid comprising an aqueous amine solution which absorbs carbon dioxide at carbon dioxide absorbing conditions in a contacting zone; and,
(e) recovering carbon dioxide from the absorber liquid.
(Ethanolamine - Wikipedia, the free encyclopedia; "Monoethanolamine (or) MEA is used in aqueous solutions for scrubbing certain acidic gases. Aqueous solutions of MEA (solutions of MEA in water) are used as a gas stream scrubbing liquid in amine treaters. For example, aqueous MEA is used to remove carbon dioxide (CO2) from flue gas." - We note that the main point of the process of our subject is to get rid of residual Oxygen in the flue gas, which both interferes directly with the absorption of Carbon Dioxide by the "amine solution" and actually degrades that amine solution. This is, again, a technique to enhance the recovery of Carbon Dioxide and make the process more efficient.)
The process ... further characterized in that the flue gas stream is heated prior to the admixture of the combustible fuel into the flue gas stream.
The process ... further characterized in that the flue gas stream is heated by indirect heat exchange against at least a portion of the flue gas stream which has passed through the combustion zone.
(Note that no external heat or energy needs to be supplied. It's all accomplished by heat exchange between treated and untreated streams of the flue gas.)
The process ... further characterized in that the flue gas stream contains less than 100 ppm oxygen after passage through the combustion zone.
The process ... further characterized in that the flue gas stream is passed through two combustion zones in series.
The process ... further characterized in that the flue gas stream is cooled and admixed with additional fuel between the two combustion zones.
The process ...further characterized in that the aqueous amine solution contains at least 20 wt.% monoethanolamine (and, that) the absorber liquid comprises monoethanolamine.
The process ... further characterized in that the flue gas stream entering the process contains more than 2 mole percent oxygen.
A process for recovering carbon dioxide from a flue gas stream which comprises the steps of:
(a) heating a flue gas stream by indirect heat exchange against a hereinafter characterized relatively hot gas stream;
(b) admixing a combustible fuel into the flue gas stream;
(c) passing the flue gas stream through a combustion zone in which the flue gas stream is contacted with a combustion catalyst at combustion-promoting conditions and thereby reducing the oxygen content of the flue gas stream to less than 200 ppm;
(Again, the "combustion catalyst" can be plain old Nickel; there's nothing too exotic or expensive being employed in any of this.)
(d) cooling at least a portion of the flue gas stream by indirect heat exchange as the previously specified relatively hot gas stream of step (a);
(e) contacting the flue gas stream with a lean carbon dioxide absorbing liquid comprising an aqueous amine solution in an absorption zone operated at absorption-promoting conditions and thereby forming a rich carbon dioxide absorbing liquid; and,
(f) recovering carbon dioxide from the rich carbon dioxide absorbing liquid.
The process ... further characterized in that the aqueous amine solution comprises monoethanolamine.
The process ... further characterized in that the flue gas stream is passed through two combustion zones in series and is admixed with additional combustible fuel between the two combustion zones.
The process ... further characterized in that the combustible fuel comprises methane (or) propane (or) carbon monoxide.
(As per the above, we can forget the "methane (or) propane", there's no need to waste them. Since this process recovers Carbon Dioxide, we can use a little bit of that recovered CO2 in a process like that seen in:
Carbon Dioxide Recycled in the Manufacture of Plastics | Research & Development; concerning: "United States Patent 4,564,513 - Process for the Production of Carbon Monoxide; 1986; Assignee: Bayer Aktiengesellschaft (AG), Germany; Abstract: Carbon monoxide is produced in an improved process in a carbon-filled, water-cooled generator in the configuration of a truncated cone in the longitudinal section, by the gasification of said carbon with a mixed gas of oxygen and carbon dioxide";
wherein it can be reacted with hot Coal and a little bit of Oxygen to make the Carbon Monoxide for use as the "admixed ... additional combustible fuel", which would, in any case, serve to enrich the CO2 content of the product gas more than would use of "methane (or) propane".
It might seem counterintuitive to do that, but, remember, the point is just to scavenge the remaining Oxygen in the flue gas, which would otherwise interfere with the Carbon Dioxide recovery.)
The process ... further characterized in that at least a portion of the heat expended in the recovery of carbon dioxide from the rich carbon dioxide absorbing liquid is obtained from the flue gas stream after the flue gas stream has passed through the combustion zone.
The process ... further characterized in that carbon dioxide is recovered by passing the rich carbon dioxide absorbing liquid into a regeneration zone which is reboiled with heat recovered by indirect heat exchange against the flue gas stream at a point downstream of the initial cooling ...
(Again, not much energy needs to be added to this process. It all seems to be derived from the heat of the flue gas and the heat of the secondary residual Oxygen-consuming catalyzed reaction.)
A process for recovering carbon dioxide from a flue gas stream which comprises the step of:
(a) heating a flue gas stream by indirect heat exchange;
(b) admixing a combustible fuel into the flue gas stream and passing the flue gas stream through a combustion zone maintained at thermal deoxidation conditions and thereby reducing the oxygen content of the flue gas stream;
(c) cooling the flue gas stream by indirect heat exchange;
(d) contacting the flue gas stream with a lean carbon dioxide absorbing liquid comprising an aqueous amine solution in an absorption zone operated at absorption-promoting conditions and thereby forming a rich carbon dioxide absorbing liquid; and,
(e) recovering carbon dioxide from the rich carbon dioxide absorbing liquid.
The process ... further characterized in that the flue gas stream is heated prior to passage into the combustion zone by indirect heat exchange against at least a portion of the flue gas stream which has passed through the combustion zone.
Background and Field: The invention relates to a process for the recovery of carbon dioxide from a flue gas stream such as is produced in the boiler of an electrical generating plant. The invention therefore relates to processes for the recovery of acid gases from a vapor stream. The invention also relates to processes which utilize a liquid absorbent, preferably an aqueous amine solution, to recover carbon dioxide from a gas stream. A specific concern of the inventive concept is the prevention or lessening of corrosion and absorbent degradation in an absorber-stripper system using an aqueous amine solution as the scrubbing liquid for the recovery of carbon dioxide.
Carbon dioxide is a useful chemical compound which finds many industrial and commercial applications. It may be used as a reactant, a relatively inert gas, or as a coolant if liquefied.
(More about it's use "as a reactant" is coming up.)
It has been recognized that carbon dioxide can be recovered from flue gas streams, in which it is present at relatively high concentrations as compared to air since it is a product of combustion. However, a number of other gases, such as nitrogen, oxygen, oxides of nitrogen and possibly sulfur oxides, are also present and result in certain operational and economic problems. One of these problems is the result of residual oxygen being present in the flue gas stream. Oxygen tends to react with amine-type absorbents thereby causing degradation of the amines into corrosive and nonproductive compounds which must be removed from the amine solution by "reclaiming". This increases the costs of operating the process and the necessity of using corrosion-resistant metals increases the cost of the required process equipment. Also, the normal absorber-stripper type of system which recovers acid gases such as carbon dioxide requires a net input of heat for the stripping or regeneration of the absorption liquid. It is believed that this has resulted in the great majority of carbon dioxide production being from sources other than flue gas.
It is therefore an objective of the subject invention to provide a process for recovering carbon dioxide from presently available gas streams. It is another objective of the subject invention to provide an economical and efficient process for recovering carbon dioxide from a flue gas stream."
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The Procon International process is apparently so effective, by the way, that, as can be learned via:
Energy Citations Database (ECD) - - Document #5817410; concerning:
"'Process to recover CO2 from flue gas gets first large-scale tryout in Texas'; J.H. Sinclair, et. al.; February, 1983; Research Organization: Procon International; Oil & Gas Journal Volume: 81:7; Abstract: This article describes a new plant that will recover 1,120 tons/day of CO2 for use in an enhanced oil recovery (EOR) project in West Texas. Feed for the plant is flue gas from an adjacent electrical power generating station. Product CO2 is pipelined from the recovery plant in a supercritical state at about 2,000 psig.
The pilot plant demonstrated the ability of Dow Chemical's Gas Spec amine solvent to recover CO2 from industrial flue gas, and confirmed that Procon/Dow's improved solvent adsorption system is effective in reducing the energy requirements";
it's efficiency has been confirmed in actual practice by a major league chemical industry player.
Okay, given that the technology is one which enables the "economical and efficient" recovery of Carbon Dioxide, specifically from "a flue gas stream", then, following, as indicated above by the inclusion of their prior art reference to "United States Patent 3,820,965 - June, 1974", is why we might be interested:
"Patent US3820965 - Method of Reducing Environmental Pollution by Utilizing Stack Gases, Resulting from the Burning of Fossil Fuels, and Water, Including Sea Water, to Manufacture Hydrocarbon Energy Fuel, Potable Water and Other Commercial Products
Patent US3820965 - METHOD OF REDUCING ENVIRONMENTAL - Google Patents
Date: June 28, 1974
Inventor: Robert New, Texas
Abstract: A method and apparatus for treating smoke stack gases diverted to minimize air pollution to recover the individual constituents thereof, namely carbon dioxide (CO2), water (H2O) and nitrogen (N2) freed from other products, such as oxides; and to recover from water ... the individual constituents thereof of interest here, namely, hydrogen (H2); and delivering the recovered carbon dioxide and the recovered hydrogen into a catalytic reaction chamber under sufficiently high temperature conditions in the presence of a suitable catalyst to establish therein a reaction temperature to support a Sabatier catalytic reaction (CO2 + 4H2 = CH4 + H2O) hydrogenating the carbon dioxide to form methane for use as fuel and potable water for commercial usage."
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The above "United States Patent 3,820,965" is just, in fact, an updated and perhaps more efficient version of the century-old Sabatier process, as we've discussed, for one instance, in:
West Virginia Coal Association | CO2 Solution Wins Nobel Prize - in 1912 | Research & Development;
"Paul Sabatier; The Nobel Prize in Chemistry; Nobel Lecture, December 11, 1912; During the period 1901 to 1905, together with Senderens, I showed that nickel is very suitable for the direct hydrogenation of nitriles into amines and, no less important, of aldehydes and acetones into corresponding alcohols. Carbon monoxide and carbon dioxide are both changed immediately into methane, which can therefore be synthesized with the greatest ease".
And, we'll have to add, that, once we have the Methane, CH4, made via the process of the above "United States Patent 3,820,965 - Method of Reducing Environmental Pollution" from Carbon Dioxide, as recovered so efficiently and economically "from a flue gas stream", we can react that CO2-derived Methane, as seen, for just one example in our report of:
Standard Oil 1954 CO2 + CH4 + H2O = Syngas | Research & Development; concerning: "United States Patent 2,676,156 - Preparation of Synthesis Gas; 1954; Assignee: Standard Oil Development Company; Abstract: The present invention relates to the preparation of a gas comprising carbon monoxide and hydrogen. In accordance with the present invention, carbon dioxide, steam and a light hydrocarbon gas such as methane (are reacted) to produce carbon monoxide and hydrogen in proportions suitable for employment in the hydrocarbon synthesis process. By manipulation of the quantities of CH4, H2O and CO2 to be reacted, desired ratios of H2 to CO in the product may be obtained";
with even more Carbon Dioxide, as perhaps again captured efficiently and economically from flue gas by the process of our primary subject, "United States Patent 4,364,915 - Process for Recovery of Carbon Dioxide from Flue Gas", and convert them both into a mixture of "carbon monoxide and hydrogen in proportions suitable for employment in the hydrocarbon synthesis process".
All of that is, of course, unless, as we're now beginning to suspect is the case with the Coal Country public press, you regular old Coal Country folk actually would prefer Cap & Trade taxes tacked on to your utility bills; ongoing economic enslavement to OPEC; and, continued high Coal Country unemployment.
It, simply, does not have to continue playing out that way.