Post-combustion device and method

Abstract

The technical field is post-combustion noxious emissions reduction. A post-combustion apparatus 100 mixes noxious gases with a post-combustion gas fuel that burns in air at least at 1950° C., more preferably greater than 2,000° C. in a chamber that mixes the gases 330 and then ignites them on entry into a combustion expansion chamber 360 with a larger sectional surface area ensuring that there is no constriction of the exhaust system from that point in the process to avoid back-pressure. A collection vessel 460 , typically using a magnet and water trap is also provided that collects particulate and other magnetic and soluble matter from the exhaust stream.

1 . A post combustion apparatus comprising:
 a) a furnace flue inlet that (in use) connects to a furnace and permits ingress of furnace exhaust gas into the post combustion apparatus, thereby defining (in use) an extreme upstream location of furnace exhaust gas entering the apparatus;   b) a post combustion exhaust chamber comprising an inlet and an outlet, the outlet defining (in use) the extreme downstream location of processed furnace exhaust gas exiting the apparatus, such that gas flows (in use) between said extreme upstream location and said extreme downstream location;   c) a cooler comprising an inlet, connected to the furnace flue inlet, an outlet and a cooling element;   d) a mixing chamber comprising an inlet, connected to the outlet of the cooler, an outlet, and a post-combustion gas fuel injection port located downstream of the mixing chamber inlet that, in use, introduces and mixes post-combustion gas fuel with furnace exhaust gas;   e) a non-return valve interposed between the cooler outlet and the mixing chamber inlet, which non-return valve is configured to permit the flow of gas substantially in one direction only from the cooler to the mixing chamber;   f) a combustion expansion chamber comprising an inlet, connected to the mixing chamber outlet, and an outlet connected to the combustion exhaust inlet;   g) an igniter located downstream of the fuel injection port within the mixing chamber or the combustion expansion chamber;   h) a gas power system connected to the post combustion apparatus configured to, in use, drive furnace exhaust gas and particulates from the furnace flue inlet downstream through the post combustion apparatus and to the post combustion exhaust outlet;   i) wherein a mode of cross-sectional combustion expansion chamber area, bounded by internal walls of the combustion expansion chamber perpendicular to the gas flow, is larger than a mode of cross-sectional mixing chamber area, defined by internal walls of the mixing chamber and exhaust perpendicular to the gas flow; and   j) wherein a mode of a cross-sectional combustion exhaust chamber area, bounded by internal walls of the combustion exhaust chamber perpendicular to the gas flow, is larger than the mode of cross-sectional mixing chamber area.   
     
     
         2 . A post combustion apparatus as claimed in  claim 1 , wherein the ratio of the mode of cross-sectional area of the combustion expansion chamber is greater than that of the mode of cross-sectional area of the mixing chamber. 
     
     
         3 . A post combustion apparatus as claimed in  claim 1 , wherein at least double that of the mode of cross-sectional area of the mixing chamber. 
     
     
         4 . A post combustion apparatus as claimed in  claim 1 , wherein the mode of a cross-sectional combustion exhaust chamber area to be at least double that of the mode of the mixing chamber area. 
     
     
         5 . A post combustion apparatus as claimed in  claim 1 , wherein the post combustion exhaust chamber outlet is connected to an exhaust flue stack. 
     
     
         6 . A post combustion apparatus as claimed in  claim 1 , wherein the exhaust path between the furnace and the exhaust stack is sealed from the air such that no additional oxygen can be introduced into the system. 
     
     
         7 . A post combustion apparatus as claimed in  claim 1 , wherein the cooling element is a steam-line heat exchanger. 
     
     
         8 . A post combustion apparatus as claimed in  claim 1 , wherein the mixing chamber is between 0.3 m and 1.5 m in length. 
     
     
         9 . A post combustion apparatus as claimed in  claim 1 , wherein the mixing chamber is between 0.8 m and 1.5 m in length. 
     
     
         10 . A post combustion apparatus as claimed in  claim 1 , wherein the post-combustion gas fuel injection port has at least one nozzle within the chamber. 
     
     
         11 . A post combustion apparatus as claimed in  claim 10 , wherein the at least one nozzle is angled to, in use, swirl post-combustion gas fuel at least partially radially perpendicular to the flow direction of the furnace exhaust gas. 
     
     
         12 . A post combustion apparatus as claimed in  claim 1 , wherein there are three post-combustion gas fuel injection ports with nozzles. 
     
     
         13 . A post combustion apparatus as claimed in  claim 12 , wherein the fuel injection ports are spaced 0.1-0.3 m apart extending in the direction of propagation of the furnace exhaust gas. 
     
     
         14 . A post combustion apparatus as claimed in  claim 10 , wherein the at least one nozzle is angled to swirl the post-combustion gas fuel in the general downstream direction. 
     
     
         15 . A post combustion apparatus as claimed in  claim 12 , wherein one of the nozzles is directed in a direction oblique to the other nozzles to impart turbulence. 
     
     
         16 . A post combustion apparatus as claimed in  claim 10 , wherein the angle of the at least one nozzle is capable of being varied. 
     
     
         17 . A post combustion apparatus as claimed in  claim 1 , wherein the combustion expansion chamber is internally ceramic lined. 
     
     
         18 . A post combustion apparatus as claimed in  claim 17 , wherein the combustion expansion chamber is internally cast ceramic lined. 
     
     
         19 . A post combustion apparatus as claimed in  claim 17 , wherein the combustion expansion chamber is internally lined using a Kaolin ceramic clay. 
     
     
         20 . A post combustion apparatus as claimed in  claim 1 , wherein the igniter is located proximal the inlet of the combustion expansion chamber. 
     
     
         21 . A post combustion apparatus as claimed in  claim 1 , wherein the igniter is a pilot light, a spark plug, a series of spark plugs or combinations of these. 
     
     
         22 . A post combustion apparatus as claimed in  claim 21 , wherein the igniter is a platinum spark plug. 
     
     
         23 . A post combustion apparatus as claimed in  claim 21 , wherein the igniter is three spark plugs. 
     
     
         24 . A post combustion apparatus as claimed in  claim 1 , wherein a matter collection chamber is installed between the combustion expansion chamber and the post combustion exhaust chamber, which matter collection chamber comprises a gas passage and a matter collection vessel. 
     
     
         25 . A post combustion apparatus as claimed in  claim 24 , wherein the matter collection vessel has at least one magnet in close association with it. 
     
     
         26 . A post combustion apparatus as claimed in  claim 25 , wherein the magnet is at least one electromagnet. 
     
     
         27 . A post combustion apparatus as claimed in  claim 26 , wherein the matter collection vessel comprises a water tray between the exhaust flow and the at least one electromagnet. 
     
     
         28 . A post combustion apparatus as claimed in  claim 1 , wherein a U-bend pipe is installed into the apparatus. 
     
     
         29 . A post combustion apparatus as claimed in  claim 28 , wherein the U-bend pipe is located before the matter collection chamber. 
     
     
         30 . A post combustion apparatus as claimed in  claim 1 , wherein water jackets are installed between the combustion expansion chamber and the extreme downstream location. 
     
     
         31 . A process of post combustion including the steps of:
 a) feeding furnace exhaust gas through a furnace flue inlet from a furnace that permits ingress of furnace exhaust gas into the post combustion apparatus, thereby defining an extreme upstream location of furnace exhaust gas entering the apparatus;   b) exhausting processed furnace exhaust gas from an outlet in a post combustion exhaust chamber comprising an inlet and the outlet, the outlet defining the extreme downstream location of processed furnace exhaust gas exiting the apparatus, such that gas flows between said extreme upstream location and said extreme downstream location;   c) feeding furnace exhaust gas into a cooler comprising an inlet from the furnace flue inlet, an outlet and a cooling element and cooling the furnace exhaust gas;   d) feeding cooled furnace exhaust gas into a mixing chamber comprising an inlet, connected to the outlet of the cooler, an outlet, and a post-combustion gas fuel injection port located downstream of the mixing chamber inlet and mixing the cooled furnace exhaust gas with post-combustion gas fuel;   e) preventing backflow of gas by passing gas through a non-return valve interposed between the cooler outlet and the mixing chamber inlet, which non-return valve is configured to permit the flow of gas substantially in one direction only from the cooler to the mixing chamber;   f) passing the mixed cooled furnace exhaust gas and post-combustion gas fuel into a combustion expansion chamber comprising an inlet, connected to the mixing chamber outlet, and an outlet connected to the combustion exhaust inlet;   g) igniting the mixed cooled furnace exhaust gas and post-combustion gas fuel using an igniter located downstream of the fuel injection port within the mixing chamber or the combustion expansion chamber,   h) driving the gas in the post combustion process by use of a gas power system connected to the post combustion apparatus that drives gas from the furnace flue inlet downstream through the post combustion apparatus and to the post combustion exhaust outlet;   i) wherein the combusting cooled furnace exhaust gas and post-combustion gas fuel mixture is free to expand through the combustion expansion chamber due to the combustion expansion chamber having a mode of cross-sectional combustion expansion chamber area, bounded by internal walls of the combustion expansion chamber perpendicular to the gas flow, is larger than a mode of cross-sectional mixing chamber area, defined by internal walls of the mixing chamber and exhaust perpendicular to the gas flow; and   j) wherein the combusted cooled furnace exhaust gas and post-combustion gas fuel mixture is free to exit the combustion expansion chamber due to the combustion expansion chamber having a mode of a cross-sectional combustion exhaust chamber area, bounded by internal walls of the combustion exhaust chamber perpendicular to the gas flow, is larger than the mode of cross-sectional mixing chamber area.   
     
     
         32 . A process of post combustion as defined in  claim 31 , wherein the combustion exhaust chamber outlet is connected to an exhaust flue stack in fluid communication with an inlet for the furnace such that at least some processed furnace exhaust gas is recycled into the furnace. 
     
     
         33 . A process of post combustion as defined in  claim 31 , wherein oxygen levels in the mixing chamber are below atmospheric levels. 
     
     
         34 . A process of post combustion as defined in  claim 33 , wherein the exhaust path between the furnace and the exhaust stack is sealed from the air and no additional oxygen is introduced into the system. 
     
     
         35 . A process of post combustion as defined in  claim 31 , wherein the exhaust path minimises back-pressure by being at least the same cross-sectional area as the expansion chamber. 
     
     
         36 . A process of post combustion as defined in  claim 31 , wherein at least some processed furnace exhaust gas is used as a heat source for generators. 
     
     
         37 . A process of post combustion as defined in  claim 31 , wherein furnace exhaust gas is cooled to between 360 K and 395 K by the cooler. 
     
     
         38 . A process of post combustion as defined in  claim 31 , wherein the post-combustion gas fuel is swirled within the mixing chamber at least partially radially perpendicular to the flow direction of the furnace exhaust gas. 
     
     
         39 . A process of post combustion as defined in  claim 31 , wherein the post-combustion gas fuel is a gas capable of combustion in air with an air flame temperature of at least 1,950° C. at STP. 
     
     
         40 . A process of post combustion as defined in  claim 39 , wherein the post-combustion gas fuel is selected from the group consisting of propane, butane, methane and propane-butane mixtures. 
     
     
         41 . A process of post combustion as defined in  claim 31 , wherein the post-combustion gas fuel is a gas capable of combustion in air with an air flame temperature at STP of at least 2,000° C. 
     
     
         42 . A process of post combustion as defined in  claim 41 , wherein the post-combustion gas fuel is selected from the group consisting of a CO/H 2  mixture (Hydrogen 55-65% and carbon monoxide 30-35%), hydrogen, acetylene, propane, cyanogen and dicyanoacetylene. 
     
     
         43 . A process of post combustion as defined in  claim 31 , wherein the post-combustion gas fuel has an ignition temperature in air at STP greater than 480° C. 
     
     
         44 . A process of post combustion as defined in  claim 43 , wherein the post-combustion gas fuel is a CO/H 2  mixture (Hydrogen 55-65% and carbon monoxide 30-35%) or hydrogen. 
     
     
         45 . A process of post combustion as defined in  claim 31 , wherein the furnace exhaust gas has been cooled and mixed sufficiently that no furnace exhaust gas in proximity to the nozzle is above the Post-combustion gas ignition temperature. 
     
     
         46 . A process of post combustion as defined in  claim 45 , wherein, the furnace exhaust gas has been cooled and mixed sufficiently that no furnace exhaust gas in proximity to the nozzle is above 395 K. 
     
     
         47 . A process of post combustion as defined in  claim 31 , wherein the angle of the nozzles is capable of being varied and the nozzles are adjusted to achieve optimum burning based on an increasing roaring sound emanating from the post combustion reaction. 
     
     
         48 . A process of post combustion as defined in  claim 31 , wherein a matter collection vessel collects particulates downstream of the combustion expansion chamber, which particulates are drawn to the vessel by an electromagnetic field and captured by a water bath. 
     
     
         49 . A process of post combustion as defined in  claim 48 , wherein turbulence of the combusting cooled furnace exhaust gas and post-combustion gas fuel mixture prior to the matter collection vessel is increased. 
     
     
         50 . A process of post combustion as defined in  claim 31 , wherein the combusting cooled furnace exhaust gas and post-combustion gas fuel mixture is cooled by contact with water jackets between the combustion expansion chamber and the extreme downstream location such that the combusted cooled furnace exhaust gas and post-combustion gas fuel mixture is cooled within 2 seconds so that the gas exits the outlet of the apparatus at a temperature lower than 500° C.