Methods of Converting Fuel

Abstract

A method for converting fuel may include reducing at least one metal oxide in a first reactor with a fuel to produce a reduced metal or a reduced metal oxide, transporting the reduced metal or reduced metal oxide from the first reactor to a second reactor, oxidizing at least a portion of the reduced metal or reduced metal oxide from the first reactor in the second reactor to produce a metal oxide intermediate, transporting the metal oxide intermediate from the second reactor to a third reactor, removing ash, char, or unwanted materials with a separation unit from the metal oxide intermediate transported from the second reactor to the third reactor, regenerating the at least one metal oxide, and transporting the regenerated metal oxide from the third reactor to the first reactor.

What is claimed is: 
     
         1 . A method for converting fuel, the method comprising:
 reducing at least one metal oxide in a first reactor with a fuel to produce a reduced metal or a reduced metal oxide, and to produce carbon dioxide, steam, or combinations thereof, wherein ceramic composite particles comprise at least one metal oxide is dispersed on a support;   transporting the reduced metal or reduced metal oxide from the first reactor to a second reactor;   oxidizing at least a portion of the reduced metal or reduced metal oxide from the first reactor in the second reactor to produce a metal oxide intermediate using an oxidant comprising steam, carbon dioxide, air, oxygen, or combinations thereof, to produce hydrogen, carbon monoxide, syngas, heat or combinations thereof, and to produce syngas, wherein the metal oxide intermediate has a higher oxidation state than the reduced metal or reduced metal oxide and a lower oxidation state than the metal oxide;   transporting the metal oxide intermediate from the second reactor to a third reactor;   removing ash, char, or unwanted materials with a separation unit from the metal oxide intermediate transported from the second reactor to the third reactor;   regenerating the at least one metal oxide by oxidizing the metal oxide intermediate of the second reactor in a third reactor to produce heat; and   transporting the regenerated metal oxide from the third reactor to the first reactor.   
     
     
         2 . The method of  claim 1 , further comprising controlling a H 2 /CO ratio of the syngas by recycling part of a second reactor product, or controlling an amount of CO 2  and steam oxidants inputted into the second reactor. 
     
     
         3 . The method of  claim 1 , wherein the ceramic composite particles comprise a promoter. 
     
     
         4 . The method of  claim 1 , wherein the fuel comprises a solid fuel, a liquid fuel, a gaseous fuel, or combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the separation unit comprises a cyclone, a sieve, a particle classifier, or combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein reduction in the first reactor and oxidation in the second reactor are carried out at pressures of between about 1 atm to about 150 atm. 
     
     
         7 . The method of  claim 1 , wherein reduction in the first reactor and oxidation in the second reactor are carried out at temperatures of between about 400° C. to about 1200° C. 
     
     
         8 . The method of  claim 1 , wherein the metal oxide comprises a metal selected from a group consisting of Fe, Cu, Ni, Sn, Co, Mn, and combinations thereof, and the support material comprises at least one component selected from the group consisting of SiC, oxides of Al, Zr, Ti, Y, Si, La, Sr, Ba, and combination thereof. 
     
     
         9 . The method of  claim 1 , further comprising generating power by producing electricity from a product of the second reactor. 
     
     
         10 . The method of  claim 1 , wherein the first reactor and the second reactor comprise at least one moving bed reactor, a series of fluidized bed reactors, a rotatory kiln, a fixed bed reactor, or combinations thereof. 
     
     
         11 . The method of  claim 1 , wherein the ceramic composite particles are radially distributed, and unconverted fuel and the ceramic composite particles are mixed. 
     
     
         12 . The method of  claim 1 , wherein the fuel is a solid fuel, and the solid fuel is delivered to the first reactor by a conveyor or pneumatic feeding device. 
     
     
         13 . The method of  claim 1 , wherein metal carbonates, metal oxides, or metal hydroxides in the first reactor capture pollutants, heavy metals, or combinations thereof. 
     
     
         14 . The method of  claim 1 , wherein the first reactor received a recycled H 2  stream at a bottom portion of the reactor. 
     
     
         15 . The method of  claim 1 , wherein the first reactor receives the fuel at a first reactor region below a feed region of the ceramic composite particles. 
     
     
         16 . The method of  claim 1 , wherein the first reactor receives feeds including oxygen, CO 2 , air, steam, and combinations thereof at a location adjacent the middle region in which the fuel is fed. 
     
     
         17 . The method of  claim 1 , wherein the ceramic composite particles comprise at least 40% by weight of the at least one metal oxide 
     
     
         18 . The method of  claim 1 , wherein the first reactor and the second reactor defines a countercurrent contacting pattern between gas and solids. 
     
     
         19 . The method of  claim 1 , wherein the first reactor is a moving bed reactor comprising an annular region created around the moving bed, the annular region being located where a fuel is introduced. 
     
     
         20 . The method of  claim 1 , wherein the first and the second reactors comprise packed beds in the form of portable cassettes, wherein the portable cassettes are configured to generate and store hydrogen in a vehicle.