Plasma assisted conversion of carbonaceous materials into a gas

Abstract

A method and system for producing product gases in which a carbonaceous material and at least one oxygen carrier are introduced into a non-thermal plasma reactor at a temperature in the range of about 300° C. to about 700° C. and a pressure in a range of about atmospheric to about 70 atmospheres and a non-thermal plasma discharge is generated within the non-thermal plasma reactor. The carbonaceous material and the oxygen carrier are exposed to the non-thermal plasma discharge, resulting in the formation of a product gas in the non-thermal plasma reactor, which product gas comprises substantial amounts of hydrocarbons, such as methane, hydrogen and/or carbon monoxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings wherein:

FIG. 1 is a schematic diagram showing a process for plasma assisted reforming of carbonaceous materials in accordance with one embodiment of this invention;

FIG. 2 is a schematic diagram showing a process for plasma assisted reforming of carbonaceous materials with micronizer in accordance with one embodiment of this invention;

FIG. 3 is an end view of an entrained flow DBD reactor in accordance with one embodiment of this invention;

FIG. 4 is a schematic diagram of a plasma assisted reforming process module in accordance with one embodiment of the system of this invention;

FIG. 5( a) is a diagram showing the equilibrium composition of a C_(s)—H₂O mixture as a function of temperature;

FIG. 5( b) is a diagram showing energy cost of the PAR process for a C_(s)—H₂O mixture under conditions of absolute quenching and ideal quenching (A, eV);

FIG. 6 is a schematic diagram showing a topping cycle for a two-stage DBD-assisted plant for co-production of hydrogen and electricity in accordance with one embodiment of the system of this invention;

FIG. 7 is a schematic diagram showing a bottoming cycle with entrained flow gasifier for a two-stage plant for co-production of hydrogen and electricity in accordance with one embodiment of the system of this invention;

FIG. 8 is a schematic diagram showing a bottoming cycle with a boiler for a two-stage plant for co-production of hydrogen and electricity in accordance with one embodiment of the system of this invention;

FIG. 9 is a diagram showing the size distribution for steam-based micronization of PRB coal;

FIG. 10 is a diagram showing PRB coal conversion as a function of particle size with and without plasma;

FIG. 11 is a schematic diagram showing a staged process for plasma assisted reforming of carbonaceous materials in accordance with one embodiment of this invention;

FIG. 12 is a schematic diagram showing a staged process for plasma assisted reforming of carbonaceous materials in accordance with another embodiment of this invention;

FIG. 13 is a diagram showing the calculated mole fraction of methane produced by the method and system of this invention as a function of temperature and at elevated pressures in which steam is a reactant;

FIG. 14 is a diagram showing the calculated mole fraction of hydrogen produced by the method and system of this invention as a function of temperature and at elevated pressures in which steam is a reactant;

FIG. 15 is a diagram showing the calculated mole fraction of carbon monoxide produced by the method and system of this invention as a function of temperature and at elevated pressures in which steam is a reactant;

FIG. 16 is a diagram showing the calculated mole fraction of methane produced by the method and system of this invention as a function of temperature and at elevated pressures without steam as a reactant;

FIG. 17 is a diagram showing the calculated mole fraction of hydrogen produced by the method and system of this invention as a function of temperature and at elevated pressures without steam as a reactant;

FIG. 18 is a diagram showing the calculated mole fraction of carbon monoxide produced by the method and system of this invention as a function of temperature and at elevated pressures without steam as a reactant;

FIG. 19 is a diagram showing the calculated mole fraction of methane produced by the method and system of this invention at atmospheric pressure as a function of temperature and at various steam-to-carbon ratios;

FIG. 20 is a diagram showing the calculated mole fraction of hydrogen produced by the method and system of this invention at atmospheric pressure as a function of temperature and at various steam-to-carbon ratios; and

FIG. 21 is a diagram showing the calculated mole fraction of carbon monoxide produced by the method and system of this invention at atmospheric pressure as a function of temperature and at various steam-to-carbon ratios.

Claims

1. A method for conversion of a carbonaceous material to a gas comprising the steps of: introducing at least one carbonaceous material and at least one oxygen carrier into a non-thermal plasma reactor at a temperature in a range of about 300° C. to about 700° C.;generating a non-thermal plasma discharge within said non-thermal plasma reactor, forming a plasma reaction zone; andexposing said at least one carbonaceous material and said at least one oxygen carrier to said non-thermal plasma discharge in said plasma reaction zone, forming a product gas comprising a gaseous component selected from the group consisting of at least one hydrocarbon, H2, CO, and mixtures thereof.

2. A method in accordance with claim 1, wherein said at least one hydrocarbon is methane.

3. A method in accordance with claim 1, wherein pressure within said non-thermal plasma reactor is in a range from about atmospheric to about 70 atmospheres.

4. A method in accordance with claim 1, wherein said at least one carbonaceous material is selected from the group consisting of fossil fuels, carbonaceous fuels, renewable energy sources, carbonaceous wastes and combinations thereof.

5. A method in accordance with claim 1, wherein said at least one oxygen carrier comprises steam.

6. A method in accordance with claim 1, wherein said non-thermal plasma discharge is generated by one of a dielectric barrier discharge, a corona discharge and an electron beam.

7. A method in accordance with claim 1, wherein said carbonaceous material and said at least one oxygen carrier are preheated to a preheat temperature of at least about 300° C.

8. A method in accordance with claim 1, wherein said carbonaceous material comprises at least one of a solid and a liquid said carbonaceous material.

9. A method in accordance with claim 8, wherein said solid carbonaceous material is introduced with said at least one oxygen carrier into a micronizer prior to being introduced into said non-thermal plasma reactor, producing a micronized carbonaceous material having an average particle size of one of less than and equal to about 20 microns.

10. A method in accordance with claim 9, wherein said micronized carbonaceous material and said at least one oxygen carrier are preheated to at least about 300° C.

11. A method in accordance with claim 9, wherein said carbonaceous material is micronized with steam in said micronizer.

12. A method in accordance with claim 1, wherein said exposing of said carbonaceous material and said at least one oxygen carrier to said non-thermal plasma discharge forms char.

13. A method in accordance with claim 12, wherein said char is used in a bottoming cycle.

14. A method in accordance with claim 12, wherein said char is recirculated to a reactant inlet of said non-thermal plasma reactor.

15. A method in accordance with claim 1, wherein at least a portion of said product gas is utilized for generation of electricity in a topping cycle.

16. A method in accordance with claim 1, wherein said exposing of said carbonaceous material and said at least one oxygen carrier to said non-thermal plasma discharge results in formation of a plurality of partially reacted carbonaceous material particles.

17. A method in accordance with claim 16, wherein said plurality of partially reacted carbonaceous material particles is introduced into a post plasma reaction zone disposed downstream of said plasma reaction zone resulting in a reduced amount of said partially reacted carbonaceous material particles.

18. A method in accordance with claim 17, wherein said reduced amount of said partially reacted carbonaceous material particles is introduced with an additional amount of said at least one oxygen carrier into a second plasma reaction zone disposed downstream of said post plasma reaction zone resulting in a further reduced amount of said partially reacted carbonaceous material particles.

19. A system for conversion of carbonaceous materials to a gas comprising: a plasma assisted reforming module, said plasma assisted reforming module comprising a first non-thermal plasma reactor having a first plasma reaction zone having at least one reactant stream inlet and a product gas outlet, a carbonaceous material source in fluid communication with said at least one reactant stream inlet, an oxygen carrier source in fluid communication with said at least one reactant stream inlet, a power supply operably connected with said first non-thermal plasma reactor, and heat supply means for supplying heat to said first non-thermal plasma reactor.

20. A system in accordance with claim 19, wherein said plasma assisted reforming module further comprises size reduction means for reducing a particle size of said carbonaceous materials, said size reduction means having a carbonaceous material inlet in fluid communication with said carbonaceous material source and a reduced size carbonaceous material outlet in fluid communication with said at least one reactant stream inlet.

21. A system in accordance with claim 20, wherein said size reduction means further comprises a steam inlet in fluid communication with a steam source.

22. A system in accordance with claim 21, wherein said size reduction means comprises a micronizer mill.

23. A system in accordance with claim 22, wherein said plasma assisted reforming module further comprises at least one heat exchanger having a reduced size carbonaceous material inlet in fluid communication with said reduced size carbonaceous material outlet and having a heated reduced size carbonaceous material outlet in fluid communication with said at least one reactant stream inlet of said non-thermal plasma reactor.

24. A system in accordance with claim 19 further comprising a bottoming cycle module operably connected with said plasma assisted reforming module, said bottoming cycle module comprising said power supply, a steam supply and said heat supply means.

25. A system in accordance with claim 24, wherein said bottoming cycle module comprises an entrained flow gasifier.

26. A system in accordance with claim 24, wherein said bottoming cycle module comprises a boiler.

27. A system in accordance with claim 24, wherein said bottoming cycle module is a two-stage plant producing gaseous fuel and electricity from a carbonaceous material.

28. A system in accordance with claim 19, wherein said non-thermal plasma reactor is a fixed bed reactor.

29. A system in accordance with claim 19 further comprising a topping cycle module operably connected with said plasma assisted reforming module.

30. A system in accordance with claim 19, wherein said plasma assisted reforming module comprises a second non-thermal plasma reactor disposed downstream of said first non-thermal plasma reactor and a post plasma reaction zone disposed between said plasma reaction zone and said second non-thermal plasma reactor, said post plasma reaction zone in fluid communication with said plasma reaction zone and said second non-thermal plasma reactor.

31. A system in accordance with claim 30, wherein said non-thermal plasma reactors are selected from the group consisting of dielectric barrier discharge, corona discharge, and electron beam.

32. A system in accordance with claim 31, wherein said non-thermal plasma reactor is a dielectric barrier discharge plasma reactor.