Method for Producing a Product Gas from Municipal Solid Waste with Particulate Classification

Abstract

A multi-stage product gas generation system converts a carbonaceous material, such as municipal solid waste, into a product gas which may subsequently be converted into a liquid fuel or other material. One or more reactors containing bed material may be used to conduct reactions to effect the conversions. Unreacted inert feedstock contaminants present in the carbonaceous material may be separated from bed material using a portion of the product gas. A heat transfer medium collecting heat from a reaction in one stage may be applied as a reactant input in another, earlier stage.

What is claimed is: 
     
         1 . A method of producing a product gas from municipal solid waste feedstock, the method comprising:
 (a) providing a fluidized bed reactor having particulate heat transfer materials therein;   (b) providing a plurality of particulate classification vessels configured to selectively receive material from the fluidized bed reactor, and separate the material by size and/or density classification;   (c) providing a source of municipal solid waste feedstock, said municipal solid waste feedstock comprising carbonaceous material and inert feedstock contaminants;   (d) introducing said municipal solid waste feedstock, including the inert feedstock contaminants, into the fluidized bed reactor;   (e) in the fluidized bed reactor, converting the carbonaceous material within the municipal solid waste feedstock into product gas in the presence of the particulate heat transfer material, while the inert feedstock contaminants remain unreacted;   (f) discharging a mixture of the particulate heat transfer material and the unreacted inert feedstock contaminants from the fluidized bed reactor, into at least one of said plurality of particulate classification vessels;   (g) introducing a classifier gas into said at least one particulate classification vessel and separating at least some of the particulate heat transfer material from at least some of the unreacted inert feedstock contaminants; and   (h) removing, from said at least one of said plurality of particulate classification vessels, said at least some of the unreacted inert feedstock contaminants.   
     
     
         2 . The method according to  claim 1 , further comprising:
 after step (g), reusing said at least some of the particulate heat transfer material, to produce additional product gas.   
     
     
         3 . The method according to  claim 2 , comprising:
 recycling said at least some of the particulate heat transfer material back into the fluidized bed reactor.   
     
     
         4 . The method according to  claim 1 , wherein:
 before step (c), subjecting the source of municipal solid waste feedstock to a feedstock preparation step, wherein the feedstock preparation step is configured to process said municipal solid waste feedstock in three or more processes selected from the group consisting of:
 (i) removing water from the feedstock, 
 (ii) reducing a size of the feedstock, 
 (iii) removing polyvinyl chloride from the feedstock, 
 (iv) removing non-ferrous metal from the feedstock, 
 (v) removing ferrous metal from the feedstock, and 
 (vi) removing pathogens from the feedstock. 
   
     
     
         5 . The method according to  claim 1 , wherein:
 the particulate heat transfer material within the fluidized bed reactor is indirectly heated with at least two pulse combustion heat exchangers.   
     
     
         6 . The method according to  claim 5 , wherein:
 the particulate heat transfer material within the fluidized bed reactor is fluidized with a mixture of oxygen and superheated steam.   
     
     
         7 . The method according to  claim 1 , comprising:
 in step (d), introducing the municipal solid waste feedstock into the fluidized bed reactor via a plurality of feedstock inputs, wherein each of the plurality of feedstock inputs has its own steam/oxygen input configured to introduce steam and oxygen to the municipal solid waste feedstock introduced via that feedstock input; and   reacting the municipal solid waste feedstock with the steam and oxygen in the fluidized bed reactor to produce the product gas.   
     
     
         8 . The method according to  claim 7 , comprising:
 providing a source of steam, and splitting the source of steam into a plurality of streams of steam, and introducing each of the plurality of streams of steam to a corresponding one of the plurality of steam/oxygen inputs; and   providing a source of oxygen, and splitting the source of oxygen into a plurality of streams of oxygen, and introducing each of the plurality of streams of oxygen to said corresponding one of the plurality of steam/oxygen inputs.   
     
     
         9 . The method according to  claim 8 , comprising:
 mixing each of the plurality of streams of steam with said corresponding one to the plurality of streams of oxygen before introducing them into one of said plurality of steam/oxygen inputs.   
     
     
         10 . The method according to  claim 8 , comprising:
 providing a steam valve and a steam valve controller configured to control the amount of steam supplied to the steam/oxygen inputs; and   providing an oxygen valve and an oxygen valve controller configured to control the amount of oxygen supplied to the steam/oxygen inputs; and   before splitting the source of steam, passing the steam through the steam valve, and controlling the amount of steam supplied to the steam/oxygen inputs with the steam valve controller; and   before splitting the source of oxygen, passing the oxygen through the oxygen valve, and controlling the amount of oxygen supplied to the steam/oxygen inputs with the oxygen valve controller.   
     
     
         11 . The method according to  claim 10 , comprising:
 mixing each of the plurality of streams of steam with said corresponding one of the plurality of streams of oxygen before introducing them into one of said plurality of steam/oxygen inputs.   
     
     
         12 . The method according to  claim 11 , comprising:
 providing a computer configured to input and/or output signals from the steam valve controller and the oxygen valve controller; and   controlling the amount of the steam passing through the steam valve with the computer and the steam valve controller, and controlling the amount of the oxygen passing through the oxygen valve with the computer and the oxygen valve controller.   
     
     
         13 . The method according to  claim 1 , wherein:
 said inert feedstock contaminants are selected from the group consisting of allen wrenches, ball bearings, batteries, bolts, bottle caps, broaches, bushings, buttons, cable, cement, chains, clips, coins, computer hard drive shreds, door hinges, door knobs, drill bits, drill bushings, drywall anchors, electrical components, electrical plugs, eye bolts, fabric snaps, fasteners, fish hooks, flash drives, fuses, gears, glass, gravel, grommets, hose clamps, hose fittings, jewelry, key chains, key stock, lathe blades, light bulb bases, magnets, metal audio-visual components, metal brackets, metal shards, metal surgical supplies, mirror shreds, nails, needles, nuts, pins, pipe fittings, pushpins, razor blades, reamers, retaining rings, rivets, rocks, rods, router bits, saw blades, screws, sockets, springs, sprockets, staples, studs, syringes, USB connectors, washers, wire, wire connectors, and zippers.   
     
     
         14 . The method according to  claim 1 , wherein:
 said particulate heat transfer material is selected from the group consisting of alumina, zirconia, sand, olivine sand, limestone, dolomite, a sorbent, a catalytic material, microballoons, microspheres, and Geldart Group B alumina microspheres.   
     
     
         15 . A method of producing jet fuel and/or diesel fuel from municipal solid waste feedstock, the method comprising:
 (i) producing the product gas according to the method of  claim 1 ;   (ii) after step (i), reducing a temperature of the product gas;   (iii) after step (ii), compressing the product gas;   (v) after step (iv), removing carbon dioxide from the product gas, and recycling at least a portion of the removed carbon dioxide to be: (v1) mixed with the municipal solid waste feedstock before introducing said municipal solid waste feedstock into the fluidized bed reactor in step (d), and/or (v2) as the source of classifier gas in step (g);   (vi) after step (v), reacting the product gas with a catalyst to produce one or more Fischer Tropsch products including tail gas;   (vii) after step (vi), upgrading the one or more Fischer Tropsch products to produce said jet fuel and/or diesel fuel, plus naphtha.   
     
     
         16 . The method according to  claim 15 , comprising:
 recycling at least a portion of the tail gas produced in step (vi) as a fuel source to create heat for converting the carbonaceous material into product gas, in step (e).   
     
     
         17 . The method according to  claim 15 , comprising:
 recycling at least a portion of the naphtha produced in step (vii) as a fuel source to create heat for converting the carbonaceous material into product gas, in step (e).   
     
     
         18 . The method according to  claim 15 , comprising:
 recycling both tail gas produced in step (vi) and naphtha produced in step (vii), as a fuel source to create heat for converting the carbonaceous material into product gas, in step (e).   
     
     
         19 . The method according to  claim 15 , comprising:
 introducing at least a portion of the tail gas produced in step (vi) along with an oxygen-containing gas, into at least one heat exchanger;   combusting the tail gas and the oxygen-containing gas within the heat exchanger to form a combustion stream; and   indirectly transferring heat from the combustion stream to the particulate heat transfer material, to convert the carbonaceous material into product gas, in step (e).   
     
     
         20 . The method according to  claim 10 , comprising:
 introducing at least a portion of the naphtha produced in step (vii) along with an oxygen-containing gas, into at least one heat exchanger;   combusting the naphtha and the oxygen-containing gas within the heat exchanger to form a combustion stream; and   indirectly transferring heat from the combustion stream to the particulate heat transfer material, to convert the carbonaceous material into product gas, in step (e).