PROCESS AND APPARATUS FOR UPGRADING COAL USING SUPERCRITICAL WATER - Patent application
We have previously cited the Carbon conversion expertise resident in Pennsylvania's Air Products and Chemicals Company.
Herein, in a United States Patent Application that is so recent we don't believe it has yet been officially published by the United States Patent and Trademark Office, and we thus can't provide you with an accurate date when this application was formulated, we see that Air Products has further developed and applied a concept we have already, from other sources, documented for you:
Water, plain old H2O, in one form or another, can be made to serve as the Hydrogen donor in hydrogenation processes that convert the Carbon content of Coal into more versatile hydrocarbons.
Comment follows excerpts from the link to:
"Patent Application Title: Process for Upgrading Coal Using Supercritical Water
Inventor: Rodney John Allam
Agents and Assignees: Air Products and Chemicals, Inc.; Allentown, PA
Abstract: Coal is converted into hydrocarbon compounds using supercritical water. The process involves two stages; a first stage in which carbonaceous material is reacted with supercritical water at above 850K to produce a first supercritical fluid reaction mixture comprising hydrocarbon compounds; and a second stage in which hydrocarbon compounds are extracted from coal mixed with at least a portion of the first supercritical fluid ... .Char from the second stage is finely divided and may be either be used outside the process, e.g. in a coal fired power station or a gasifier, or used as at least a portion of the carbonaceous material used in the first stage.
Claims: A process for producing hydrocarbon compounds from coal, said process comprising:reacting carbonaceous material with supercritical water ... .
(And) wherein char is produced as a by product of said extraction of coal, said process comprising using at least a portion of said char as at least a portion of said carbonaceous material.
(And) wherein said SCW (Super Critical Water) comprises oxygen to combust a portion of said carbonaceous material to provide at least a portion of the heat required to react said carbonaceous material with said SCW.
Background: The present invention relates to upgrading coal using supercritical water ("SCW"), i.e. using SCW to extract valuable products, e.g. "light" hydrocarbons, hydrogen and carbon monoxide, from coal. The invention may be applied to any type of coal ... .
Partial oxidation of coal using pure oxygen ... yields a synthesis gas ("syngas") mixture (containing predominantly carbon monoxide and hydrogen) which can be used as a ... raw material for the production of hydrogen, hydrocarbons and other chemicals by a variety of catalytic reactions.
There is ... a need for a process for primary treatment of coal which can be used to produce products such as gaseous fuels; valuable hydrocarbon compounds; heat energy (which is easily convertible to electrical energy); and an easily-handled ash residue. The process should also remove pollutants such as sulfur compounds ... .
The use of SCW to upgrade coal has been suggested before (as specified, wherein) gaseous products including hydrogen and gaseous hydrocarbons such as methane are (produced).
SCW conversion is a highly efficient process of coal transformation into supercritical products. The efficiency of the total conversion was observed to be no less that 93.5%.
"SCW" is water which is at a temperature and pressure exceeding its critical temperature and critical pressure. The critical temperature of water is the temperature above which water cannot be liquefied by an increase in pressure, i.e. 374° C. (and, the) critical pressure of water is the pressure of water at its critical temperature, i.e. 221 bar.
The process according to the first aspect of the present invention comprises, in a first (or hydrogenation) stage, reacting carbonaceous material with SCW ... to produce a first supercritical fluid mixture comprising hydrocarbon compounds. Coal is mixed with at least a portion of the first supercritical fluid mixture or a supercritical fluid mixture derived therefrom to form a supercritical fluid reaction mixture ... . In a second (or extraction) stage, the supercritical fluid reaction mixture is maintained (at specified temperatures) for sufficient time to extract hydrocarbon compounds from the coal and produce a second supercritical fluid mixture comprising hydrocarbon compounds.
'Hydrocarbon compounds' are hydrocarbon compounds having a lower molecular weight than the coal feedstock. The hydrocarbon compounds are typically produced in three fractions, i.e. a gas fraction; a liquid hydrocarbon fraction having a density less than water; and a hydrocarbon fraction having a density greater than water. The gas fraction usually comprises ... alkanes such as methane, ethane and propane; and alkenes such as ethene and propene.
The liquid hydrocarbon fraction usually comprises a mixture of benzene; toluene; and xylenes ("BTX").
("BTX", we remind you, as documented in earlier of our reports, is a starting blend from which petroleum refineries formulate Gasoline.)
One advantage of the present invention over the prior art is that, whilst a hydrogenation catalyst may be used in the first stage, use of such a catalyst is not necessary and, in preferred embodiments, the reaction of carbonaceous material with SCW is uncatalyzed.
The second supercritical fluid mixture usually comprises solid particles of carbonaceous char and ash. The solid particles are usually separated from the second supercritical fluid mixture to form separated solid particles and particle-free, second supercritical fluid mixture. The separated char is usually in a finely reduced form. In some preferred embodiments, at least a portion of the separated char is used as feed to a conventional coal fired power station or to a gasifier. In other preferred embodiments, at least a portion of the separated char is used as at least a portion of the carbonaceous material fed to the first reaction zone.
... the present invention may be applied to the conversion of any type of coal."
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We'll leave it there.
Air Products suggests Coal combustion as one way to get the Water heated and pressurized; but, we submit, instead, that:
Coal could be conserved, and CO2 emissions avoided entirely, if environmental energy, i.e., Solar or Hydro, were harnessed to the task of getting the Water up to the necessary pressure and temperature.
And, don't be misled or discouraged by Air Products' insistence on use of the Kelvin scale to specify the needed temperatures. As in their one translation, as we reproduced, above, into the Celsius scale, only twice the boiling temperature of Water is required.
The pressures needed are quite high; but, they are within the realm of current industrial practice.
Air Products and Chemicals definitely knows how to handle high-pressure gases.
In any case, using only Water as a co-reactant, "93.5%" of Coal can be converted into such useful products as "methane, ethane and propane", and the combination of Gasoline blending components, "benzene; toluene; and xylene".
The Methane, we again remind you, can be reacted, in bi-reforming and tri-reforming reactions, such as explained by scientists such as Chunsan Song and Craig Grimes at Penn State University, with Carbon Dioxide recovered from whatever source; with both gases being converted by such reactions into liquid hydrocarbons.
And, note:
If environmental energy were harnessed to the task of heating and pressurizing the Water, there would, as we read it, be no CO2 generated in, or released from, this Pennsylvania Coal conversion process itself.