Production of activated char using hot gas

Abstract

A gas mixture preheated to high temperatures using an oxy-fuel, an oxygen-enriched air-fuel or an air-fuel burner is used to devolatilize and partially oxidize carbonaceous feedstock, thereby producing an active residual char that can be used in applications utilizing activated carbon. Use of hot gas and ground carbonaceous feedstock allows the equipment to be minimized, thereby allowing the activated carbon to be produced at or near points of use, for example the production of activated char at or near utility boilers for use in the reduction of mercury emissions from flue gas streams.

1 . A method for producing activated char, the method comprising:
 generating at least one gas stream containing an oxidant, the gas stream having a temperature of at least 800° F.;   mixing carbonaceous feedstock with the at least one gas stream such that the carbonaceous feedstock undergoes devolatilization and partial oxidation, thereby producing activated char and byproducts.   
     
     
         2 . The method of  claim 1 , wherein the byproducts comprise carbon monoxide and hydrogen. 
     
     
         3 . The method of  claim 2 , wherein the byproducts are suitable for use as fuel. 
     
     
         4 . The method of  claim 3 , wherein the byproducts are used as a reburning fuel. 
     
     
         5 . The method of  claim 1 , wherein the activated char and the byproducts are produced at a facility that utilizes the activated char. 
     
     
         6 . The method of  claim 1 , further comprising quenching the powdered activated char with a quenching media. 
     
     
         7 . The method of  claim 6 , wherein the quenching media comprises a fog of water droplets. 
     
     
         8 . The method of  claim 7 , wherein the quenching media includes a dopant for doping the activated char. 
     
     
         9 . The method of  claim 8 , wherein the dopant is KBr. 
     
     
         10 . The method of  claim 7 , wherein the activated char is further treated with steam to increase the surface area thereof. 
     
     
         11 . The method of  claim 6 , wherein the quenching media comprises nitrogen. 
     
     
         12 . The method of  claim 11 , wherein the activated char is further treated with steam to increase the surface area thereof. 
     
     
         13 . The method of  claim 1 , further comprising adding a secondary reactive gas prior to mixing the carbonaceous feedstock with the at least one gas stream. 
     
     
         14 . The method of  claim 13 , wherein the secondary reactive gas stream comprises steam. 
     
     
         15 . The method of  claim 1 , further comprising adding a solid, a liquid or a gaseous additive subsequent to devolatilization and partial oxidation. 
     
     
         16 . The method of  claim 1 , wherein the temperature of the at least one gas stream is at least 2000° F. 
     
     
         17 . The method of  claim 1 , wherein the activated char is a powder. 
     
     
         18 . The method of  claim 1 , wherein the carbonaceous feedstock is selected from coals, petroleum coke, biomass materials, nutshells, nut hulls and mixtures thereof. 
     
     
         19 . The method of  claim 18 , wherein the carbonaceous material comprises coal. 
     
     
         20 . The method of  claim 1 , wherein the step of generating the at least one gas stream comprises mixing an oxidant and a fuel. 
     
     
         21 . The method of  claim 20 , further including mixing steam with the oxidant and the fuel. 
     
     
         22 . The method of  claim 20 , wherein the oxidant and the fuel are mixed at or near the stoichiometric ratio of the oxidant and the fuel. 
     
     
         23 . The method of  claim 20 , wherein the oxidant and the fuel are mixed in a ratio of excess oxidant than the stoichiometric ratio of the oxidant and the fuel. 
     
     
         24 . A method for producing activated char, the method comprising:
 generating a superheated gas stream, the gas stream having a temperature of at least 800° F.;   mixing carbonaceous feedstock with the superheated gas stream such that the carbonaceous feedstock undergoes devolatilization and partial oxidation, thereby producing activated char and byproducts.   
     
     
         25 . The method of  claim 1 , wherein the byproducts comprise carbon monoxide and hydrogen. 
     
     
         26 . The method of  claim 24 , wherein the byproducts are suitable for use as fuel. 
     
     
         27 . The method of  claim 26 , wherein the byproducts are used as a reburning fuel. 
     
     
         28 . The method of  claim 24 , wherein the activated char and the byproducts are produced at a facility that utilizes the activated char. 
     
     
         29 . The method of  claim 24 , further comprising quenching the powdered activated char with a quenching media. 
     
     
         30 . The method of  claim 29 , wherein the quenching media comprises a fog of water droplets. 
     
     
         31 . The method of  claim 30 , wherein the quenching media includes a dopant for doping the activated char. 
     
     
         32 . The method of  claim 31 , wherein the dopant is KBr. 
     
     
         33 . The method of  claim 29 , wherein the activated char is further treated with steam to increase the surface area thereof. 
     
     
         34 . The method of  claim 29 , wherein the quenching media comprises nitrogen. 
     
     
         35 . The method of  claim 34 , wherein the activated char is further treated with steam to increase the surface area thereof. 
     
     
         36 . The method of  claim 24 , further comprising adding a secondary reactive gas prior to mixing the carbonaceous feedstock with the at least one gas stream. 
     
     
         37 . The method of  claim 36 , wherein the secondary reactive gas stream comprises steam. 
     
     
         38 . The method of  claim 24 , further comprising adding a solid, a liquid or a gaseous additive subsequent to devolatilization and partial oxidation. 
     
     
         39 . The method of  claim 24 , wherein the temperature of the at least one gas stream is at least 2000° F. 
     
     
         40 . The method of  claim 24 , wherein the activated char is a powder. 
     
     
         41 . The method of  claim 24 , wherein the carbonaceous feedstock is selected from coals, petroleum coke, biomass materials, nutshells, nut hulls and mixtures thereof. 
     
     
         42 . The method of  claim 41 , wherein the carbonaceous material comprises coal. 
     
     
         43 . A method for producing activated char, the method comprising:
 generating at least one gas stream containing an oxidant, the gas stream having a temperature of at least 800° F.;   mixing carbonaceous feedstock containing a dopant with the at least one gas stream such that the carbonaceous feedstock undergoes devolatilization and partial oxidation, thereby producing activated char and byproducts.   
     
     
         44 . The method of  claim 43 , wherein the dopant comprises NaBr, KBr or mixtures thereof. 
     
     
         45 . The method of  claim 43 , wherein the carbonaceous material comprises coal. 
     
     
         46 . The method of  claim 45 , wherein the coal comprises a sub-bituminous coal. 
     
     
         47 . The method of  claim 46 , wherein the sub-bituminous coal comprises Powder River Basin (PRB) coal. 
     
     
         48 . The method of  claim 45 , wherein the coal comprises a bituminous coal. 
     
     
         49 . The method of  claim 48 , wherein the bituminous coal comprises a Utah bituminous coal. 
     
     
         50 . The method of  claim 45 , wherein the coal comprises lignite coal. 
     
     
         51 . The method of  claim 43 , wherein the carbonaceous feedstock and dopant are formed by wet mixing prior to mixing with the at least one gas stream. 
     
     
         52 . The method of  claim 51 , wherein the dopant comprises NaBr, KBr or mixtures thereof. 
     
     
         53 . The method of  claim 51 , wherein the carbonaceous material comprises coal. 
     
     
         54 . The method of  claim 45 , wherein the coal comprises a sub-bituminous coal. 
     
     
         55 . The method of  claim 54 , wherein the sub-bituminous coal comprises Powder River Basin (PRB) coal. 
     
     
         56 . The method of  claim 45 , wherein the coal comprises a bituminous coal. 
     
     
         57 . The method of  claim 56 , wherein the bituminous coal comprises a Utah bituminous coal. 
     
     
         58 . The method of  claim 45 , wherein the coal comprises lignite coal. 
     
     
         59 . The method of  claim 43 , wherein the carbonaceous feedstock and dopant are formed by dry mixing prior to mixing with the at least one gas stream. 
     
     
         60 . The method of  claim 59 , wherein the dopant comprises NaBr, KBr or mixtures thereof. 
     
     
         61 . The method of  claim 59 , wherein the carbonaceous material comprises coal. 
     
     
         62 . The method of  claim 61 , wherein the coal comprises a sub-bituminous coal. 
     
     
         63 . The method of  claim 62 , wherein the sub-bituminous coal comprises Powder River Basin (PRB) coal. 
     
     
         64 . The method of  claim 61 , wherein the coal comprises a bituminous coal. 
     
     
         65 . The method of  claim 64 , wherein the bituminous coal comprises a Utah bituminous coal. 
     
     
         66 . The method of  claim 61 , wherein the coal comprises lignite coal.