Flash-tube ignition system

A combustible fuel gas burner assembly comprising:

• supply means feeding air and gas to a burning zone for combustion thereat;
• an exhaust tube having an inlet at said burning zone for carrying away the products of said combustion and, in the absence of said combustion, for carrying away the mixture of said air and gas;
• means for varying the ratio of air to gas in said mixture in said exhaust tube such that the flame propagation speed of said mixture in said exhaust tube changes through a spectrum of values at least one of which is greater than the flow velocity of said mixture in said exhaust tube;
• an ignition source spaced from said burning zone for igniting said mixture in said exhaust tube when said flame propagation speed is greater than said flow velocity, whereby said exhaust tube also serves as a flash-tube through which a flame travels from said ignition source to said burning zone;
• wherein said means for varying said ratio in said exhaust tube is disposed in said supply means;
• said means for varying said ratio controls the amount of said air fed to said burning zone;
• said supply means comprises a primary supply feeding gas and primary air to said burning zone and a secondary supply feeding secondary air to said burning zone, said mixture in said exhaust tube comprising said gas plus said primary air plus said secondary air, and wherein said means for varying said ratio comprises control means disposed in said secondary supply for controlling the amount of said secondary air fed to said mixture;
• said control means comprises a valve operable between open and closed positions for controlling the amount of said secondary air in said mixture to thereby vary said ratio such that said flame propagation speed changes through said spectrum;
• and
• said primary supply comprises a primary line supplying said gas and said primary air to an elongated vertically extending primary tube to turn at a first cone at the top thereof, and wherein said secondary supply comprises a secondary line supplying said secondary air to an elongated vertically extending secondary tube concentrically surrounding said primary tube, said secondary air mixing with remaining gas unburned in said first cone to burn as a second cone, said first and second cones forming said burning zone, and wherein said exhaust tube concentrically surrounds said secondary tube and extends above said primary and secondary tubes, said exhaust tube being sealed at the top such that the products of combustion of said first and second cones are exhausted downwardly through said exhaust tube and, in the absence of said combustion, said mixture flows downwardly through said exhaust tube.

A combustible fuel gas burner assembly comprising:

• supply means feeding air and gas to a burning zone for combustion thereat;
• an exhaust tube having an inlet at said burning zone for carrying away the products of said combustion and, in the absence of said combustion, for carrying away the mixture of said air and gas;
• means for varying the ratio of air to gas in said mixture in said exhaust tube such that the flame propagation speed of said mixture in said exhaust tube changes through a spectrum of values at least one of which is greater than the flow velocity of said mixture in said exhaust tube;
• an ignition source spaced from said burning zone for igniting said mixture in said exhaust tube when said flame propagation speed is greater than said flow velocity, whereby said exhaust tube also serves as a flash-tube through which a flame travels from said ignition source to said burning zone;
• wherein said supply means comprises a primary supply feeding gas and primary air to said burning zone and a secondary supply feeding secondary air to said burning zone, said mixture in said exhaust tube comprising said gas plus said primary air plus said secondary air;
• and
• wherein said primary supply comprises a primary line supplying said gas and said primary air to an elongated vertically extending primary tube to burn as a first cone at the top thereof, and wherein said secondary supply comprises a secondary line supplying said secondary air to an elongated vertically extending secondary tube concentrically surrounding said primary tube, said secondary air mixing with remaining gas unburned in said first cone to burn as a second cone, said first and second cones forming said burning zone, and wherein said exhaust tube concentrically surrounds said secondary tube and extends above said primary and secondary tubes, said exhaust tube being sealed at the top such that the products of combustion of said first and second cones are exhausted downwardly through said exhaust tube and, in the absence of said combustion, said mixture flows downwardly through said exhaust tube.