Compositions – Gaseous compositions – Carbon-oxide and hydrogen containing
Reexamination Certificate
1999-05-27
2001-02-13
Griffin, Steven P. (Department: 1754)
Compositions
Gaseous compositions
Carbon-oxide and hydrogen containing
C423S418200, C423S437100, C423S580100
Reexamination Certificate
active
06187226
ABSTRACT:
TECHNICAL FIELD
This present invention relates to equipment for thermal conversion of a source of carbon atoms and a source of oxygen atoms and other reactants such as methane to desired end products, particularly carbon monoxide and hydrogen. The end products may be either a gas or ultrafine solid particles. It also relates specifically to methods for effectively producing such end products.
BACKGROUND OF THE INVENTION
Carbon dioxide is a generally inert gas that is produced in abundance by combustion processes. Whether it is slash and burn deforesting that occurs in developing countries or it is the numerous combustion processes of industrialized nations, carbon dioxide is constantly being produced. Carbon dioxide is also often found in natural gas. As a natural gas component, carbon dioxide is a contaminant that lowers the burn efficiency of the natural gas. Natural gases that are being extracted from the North Slopes of Alaska may contain up to 20% carbon dioxide or more. At any amount, carbon dioxide acts as a contaminant for specific volume energy output. Additionally, in petroleum refining operations, natural gas is often flared and carbon dioxide is present in abundance in the combustion products.
If carbon dioxide could be used more efficiently, it could be converted to valuable feed stocks such as carbon monoxide. Carbon monoxide is also considered one of the primary culprits in global warming theory. As such, if carbon monoxide emissions were reduced in all processes where it is a product, the global warming rate would be affected.
Carbon monoxide is a valuable intermediate for many industries. The prior technology for production of carbon monoxide involved steam and/or catalytic reforming of natural gas to form the products of carbon monoxide and diatomic hydrogen.
It would be an improvement in the art to utilize the abundant carbon dioxide, that is produced by the large number of operations around the globe, to generate the valuable intermediate of carbon monoxide.
SUMMARY OF THE INVENTION
The present invention relates to the formation of carbon monoxide and hydrogen from feed stocks containing carbon, oxygen, and simple hydrocarbons such as methane. The present invention also relates to an integrated liquid natural gas reforming and hydrogen combustion process in which carbon monoxide and diatomic hydrogen are produced.
The inventive process operates by injecting carbon dioxide and other optional reactants into the inlet end of a reactor chamber and rapidly heating the reactants to produce a hot carbon monoxide product stream which flows toward the outlet end of the reactor chamber. The reactor chamber may have a predetermined length that is sufficient to allow heating of the reactant stream to a selected equilibrium temperature and a preferred equilibrium composition of primarily carbon monoxide and diatomic hydrogen.
Upon reaching the selected equilibrium temperature, the desired end product is available within the product stream as a thermodynamically stable or unstable reaction product at a location adjacent to the outlet end of the reaction chamber. The gaseous stream is passed through a restrictive convergent-divergent nozzle arranged coaxially within the remaining end of the reactor chamber to rapidly cool the gaseous stream by converting thermal energy to kinetic energy as a result of substantially adiabatic and isentropic expansion as it flows axially through the nozzle to minimize back reactions. Thereby the desired end product within the flowing gaseous stream is retained. Subsequently, the product stream is cooled and slowed down in velocity.
Preferably the rapid heating step is accomplished by introducing a stream of plasma arc gas to a plasma torch at the inlet end of the reactor chamber to produce a plasma within the reactor chamber which extends toward its outlet end.
An alternate method of this invention uses a virtual convergent-divergent nozzle. This is accomplished by directing one or more streams of particles, droplets, liquid, or gas into the main flow stream of the reaction chamber such that the main reactant flow stream is forced to flow as though a real convergent-divergent nozzle were present. This phenomena occurs because the reduced axial momentum of the directing flow effectively impedes the flow of the main stream, thereby forcing the majority of the main stream to flow around the impeding stream, similar to the flow through the restriction of a conventional converging-diverging nozzle. A similar cooling effect is achieved with the virtual nozzle. The directing or impeding stream(s) can play other roles than merely providing the virtual nozzle effect. In addition to keeping the main flow stream away from the wall, they can interact with the main stream further downstream in various ways to provide, for example, enhanced heat transfer, mixing, chemical reaction, etc. The virtual nozzle effect can also be utilized in combination with a conventional converging-diverging nozzle to achieve optimal performance. To obtain the desired expansion and cooling it will be necessary to adjust the velocity of the reactants, the quantity of the reactants, the number and position of the supply inlets, and diameter of the reaction chamber.
The present invention converts a predominantly carbon dioxide stream to carbon monoxide with minor amounts of impurities. The present invention also converts a carbon dioxide-rich hydrocarbon stream into carbon monoxide, diatomic hydrogen, and minor impurities including elemental carbon.
The present invention also relates to an on-board plasma quench reformer system for hydrocarbon fuel such as a natural gas fuel. In the on-board plasma quench reformer, either liquid natural gas or compressed natural gas is vaporized and converted into hydrogen and a selection of carbon compounds including carbon dioxide, carbon monoxide, and elemental carbon. At least the hydrogen is then supplied to the internal combustion engine as a reformed fuel source.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
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Detering Brent A.
Kong Peter C.
Bechtel BWXT Idaho LLC
Griffin Steven P.
Strickland Jonas N.
Workman & Nydegger & Seeley
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