# US 5,707,408 A · Method and apparatus for production of fuel gas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,408 A - Document ID: US5707408A - Status: Granted - Kind: A - Application number: 08/532,578 - Filed: 1995-10-20 - Granted: 1998-01-13 - Earliest claimed: 1993-04-22 - Assignees: Yugen Kaisha Libo - Inventors: Hideoki Kudo - Web page: https://patentgrep.com/patent/US5707408A ## CPC - C10L 3/00: Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas - C10G 2400/26: Fuel gas - C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS - C10G: CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION (cracking to hydrogen or synthesis gas C01B; cracking or pyrolysis of hydrocarbon gases to individual hydrocarbons or mixtures thereof of definite or specified constitution C07C; cracking to cokes C10B); RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES ## Abstract Production of fuel gas which generates little nitrogen oxides on combustion, has a prolonged combustion period for unit volume, and presents a high combustion temperature. Alcohol or other liquid fuel is burnt in a fuel layer 20 in a combustion chamber 18 to generate a primary fuel gas, which is mixed in a gas pipe 14 with pressurized air ejected by an air nozzle 16, where spiral flow of air is formed around the ejected air. The ratio of the cross section of the primary fuel gas flow to that of air ejected from the air nozzle 16 is first decreased and then increased, so that vortices are formed in the area where the cross section changes to react the primary fuel gas with air and decompose hydrocarbons in the primary fuel gas into carbon and hydrogen with high reactivity, thus producing a fuel gas capable of high temperature combustion with low amount of nitrogen oxides generated. ## Claims ### Claim 1 An apparatus for production of fuel gas, comprising: a combustion chamber; a fuel gas source which supplies primary fuel gas to said combustion chamber where said fuel gas is heated to a temperature equal to or higher than the boiling point and lower than the flash point; a gas pipe having a first end and a second end, said first end communicating with said combustion chamber, said gas pipe defining a gas pipe axis extending from a cross-sectional center of said first end of said gas pipe to a cross-sectional center of said second end of said gas pipe, said gas pipe having at least one inlet hole through which an interior of said gas pipe communicates with an exterior of said gas pipe; an outlet pipe, said outlet pipe communicating with said second end of said gas pipe, said outlet pipe having a cross-sectional area perpendicular to said gas pipe axis which is larger than the cross-sectional area of said gas pipe perpendicular to said gas pipe axis; and an air nozzle, said air nozzle having an entrance end and an exit end, said entrance end communicating with a source of air, said exit end of said air nozzle being positioned in said gas pipe, said air nozzle defining an air nozzle axis extending from a cross-sectional center of said entrance end of said air nozzle to a cross-sectional center of said exit end of said air nozzle, said air nozzle axis being substantially collinear with said gas pipe axis. ### Claim 2 (depends on 1) An apparatus for production of fuel gas according to claim 1, in which said air nozzle is arranged so that its position is adjustable along the gas pipe axis. ### Claim 3 (depends on 1) An apparatus for production of fuel gas according to claim 1, in which said at least one inlet hole is positioned close to said exit end of said air nozzle. ### Claim 4 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising fins to form a spiral flow placed around the exit end of said air nozzle and arranged in the same oblique angle against the gas flow, so that said primary fuel gas forms a spiral flow around the pressurized air from said air nozzle. ### Claim 5 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising a gas nozzle which is connected to said fuel gas source, located close to the exit end of said air nozzle in a direction oblique to said gas pipe axis and ejects the primary fuel gas. ### Claim 6 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising two or more small nozzles with different lengths arranged around said gas pipe axis, serving also as a means to form mixed flow, through which air is ejected to form a mixed flow. ### Claim 7 (depends on 6) An apparatus for production of fuel gas according to claim 6, in which said small nozzles are arranged spirally along a virtual conical surface around said gas pipe axis placed with its apex directed downstream but not protruding from the end of the pipe. ### Claim 8 (depends on 7) An apparatus for production of fuel gas according to claim 7, in which a virtual spiral formed by the tip of said small nozzles is right-handed when viewed downstream. ### Claim 9 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising a surface inclined to said gas pipe axis and at least one orifice formed through the surface, and is located in said gas pipe between said second end of said gas pipe and said exit end of said air nozzle. ### Claim 10 (depends on 9) An apparatus for production of fuel gas according to claim 9, in which said surface consists of a plate through which a number of orifices are formed. ### Claim 11 (depends on 9) An apparatus for production of fuel gas according to claim 9, in which said surface is constructed by forming metal mesh in a conical spiral. ### Claim 12 (depends on 1) An apparatus for production of fuel gas according to claim 1, in which said air nozzle is arranged so that its position is adjustable along said gas pipe axis. ### Claim 13 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising a first reaction cylinder made of a heat-resistant material with a number of through holes formed as a hollow cone with the base directed downstream; and a second reaction coil formed by winding spirally a plate of a heat-resistant material with a number of through holes with one of the ends connected to the base of said first reaction cylinder, said air nozzle being connected to the apex of said first reaction cylinder to eject pressurized air into the latter. ### Claim 14 (depends on 1) An apparatus for production of fuel gas according to claim 1, further comprising a reaction cylinder made of a heat-resistant material with a number of through holes formed by spirally winding a sheet of the material as a hollow truncated cone with the larger base directed downstream, said air nozzle being connected to the center of the smaller base of said reaction cylinder to eject pressurized air into the latter. ### Claim 15 (depends on 1) An apparatus for production of fuel gas as recited in claim 1, said combustion chamber having a wall positioned between said entrance end of said air nozzle and said exit end of said air nozzle, said air inlet axis passing through a center of said wall, said wall having at least one opening formed therethrough such that an interior of said combustion chamber communicates with an exterior of said combustion chamber. ### Claim 16 (depends on 1, 2, 3, 4) An apparatus for production of fuel gas according to any one of claims 1-4, in which said fuel gas source comprises a vessel to contain the fuel and a means to heat the fuel. ### Claim 17 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14) An apparatus for production of fuel gas according to any one of claims 1-14, in which said fuel gas source consists of a combustion chamber, in which the fuel is burnt, provided with an air inlet and a combustion air outlet, the latter being connected with said first end of said gas pipe. ### Claim 18 (depends on 17) An apparatus for production of fuel gas according to claim 17, in which said combustion chamber is a cylinder with said air inlet at one end and said combustion gas outlet on the other end, the fuel being formed into a layer covering at least a part of the inner surface of said cylinder. ### Claim 19 An apparatus for production of fuel gas according to claim, 18, in which said fuel layer in said combustion chamber is formed using a porous material impregnated with a liquid fuel. ### Claim 20 A method for production of fuel gas, comprising: heating fuel to a temperature equal to or higher than the boiling point and lower than the flash point; supplying said fuel to a first end of a gas pipe, said gas pipe also having a second end, said gas pipe defining a gas pipe axis extending from a cross-sectional center of said first end of said gas pipe to a cross-sectional center of said second end of said gas pipe, said second end of said gas pipe communicating with an outlet pipe, said outlet pipe having a cross-sectional area perpendicular to said gas pipe axis which is larger than the cross-sectional area of said gas pipe perpendicular to said gas pipe axis; feeding air to an entrance end of an air nozzle, said air nozzle also having an exit end, said exit end of said air nozzle being positioned in said gas pipe, said air nozzle defining an air nozzle axis extending from a cross-sectional center of said entrance end of said air nozzle to a cross-sectional center of said exit end of said air nozzle, said air nozzle axis being substantially collinear with said gas pipe axis; feeding air through at least one inlet hole formed in said gas pipe through which an interior of said gas pipe communicates with an exterior of said gas pipe; thereby mixing said fuel gas and air to form a secondary fuel gas. ### Claim 21 (depends on 20) A method for production of fuel gas according to claim 20, in which said primary fuel gas contains the combustion gas formed by combustion of said fuel. ### Claim 22 (depends on 20) A method for production of fuel gas according to claim 20, in which said primary fuel gas contains the combustion gas formed by combustion of said fuel and unreacted gases. ### Claim 23 (depends on 20) A method for production of fuel gas according to claim 20, in which said primary fuel gas contains air. ### Claim 24 (depends on 20) A method for production of fuel gas according to claim 20, in which said fuel is at least one of liquid, gaseous and solid fuel. ### Claim 25 (depends on 24) A method for production of fuel gas according to claim 24, in which said liquid fuel is at least one of alcohol and liquid hydrocarbon. ### Claim 26 (depends on 24) A method for production of fuel gas according to claim 24, in which said gaseous fuel is at least one of natural gas, carbon monoxide, hydrogen, methane, propane and butane. ### Claim 27 (depends on 24) A method for production of fuel gas according to claim 24, in which said solid fuel is at least one of coal, wax, charcoal, cellulose and coke. ### Claim 28 (depends on 20) A method for production of fuel gas as recited in claim 20, wherein said heating said fuel gas is conducted in a combustion chamber which communicates with said first end of said gas pipe, further comprising feeding air into said combustion chamber through at least one opening in a wall of said combustion chamber, said wall being positioned such that a center thereof is located on said gas pipe axis.