A burner includes a main flange, an oxidant inlet coupled to the main flange, a combustion fuel inlet coupled to the main flange, a nozzle pipe coupled to the main flange, an outer pipe coupled to the main flange, and a diffuser coupled to the nozzle pipe and the outer pipe. The nozzle pipe has an inner volume in fluid communication with the oxidant inlet. The outer pipe is around the nozzle pipe. An annular volume is at least partially defined by the main flange, the nozzle pipe, the outer pipe, and the diffuser. The annular volume is in fluid communication with the combustion fuel inlet. The diffuser may be flat.

A burner includes a main flange, an oxidant inlet coupled to the main flange, a combustion fuel inlet coupled to the main flange, a nozzle pipe coupled to the main flange, an outer pipe coupled to the main flange, and a diffuser coupled to the nozzle pipe and the outer pipe. The nozzle pipe has an inner volume in fluid communication with the oxidant inlet. The outer pipe is around the nozzle pipe. An annular volume is at least partially defined by the main flange, the nozzle pipe, the outer pipe, and the diffuser. The annular volume is in fluid communication with the combustion fuel inlet. The diffuser may be flat.

A burner tip apparatus which is resistant to plugging, and a staged air method of operation which reduces the peak temperature of the flame of the burner tip to provide low levels of NO.sub.x and other emissions. The burner tip can be used as an auxiliary burner tip for stabilizing a main burner flame, or for other purposes.

A burner tip apparatus which is resistant to plugging, and a staged air method of operation which reduces the peak temperature of the flame of the burner tip to provide low levels of NO.sub.x and other emissions. The burner tip can be used as an auxiliary burner tip for stabilizing a main burner flame, or for other purposes.

A burner includes a diffuser wall delimiting an inner space in flow communication with an inlet passageway and forming a diffuser perforation for the gas mixture to pass from the inner space to an outer side of the diffuser wall where combustion occurs. A pilot chamber is formed in the inner space and delimited by a pilot portion of the diffuser wall, forming a pilot perforation, and by a pilot wall extended into the inner space. The pilot chamber forms pilot inlet openings supplying air/gas-air pre-mixture into the pilot chamber. A pilot gas opening supplies non-premixed fuel gas into the pilot chamber. A main chamber formed in the inner space is delimited by a diffuser wall main portion, forming a main perforation, and by the pilot wall. The main chamber delimits a main inner volume and is in flow communication with the inlet passageway to supply air/gas-air pre-mixture.

A burner includes a diffuser wall delimiting an inner space in flow communication with an inlet passageway and forming a diffuser perforation for the gas mixture to pass from the inner space to an outer side of the diffuser wall where combustion occurs. A pilot chamber is formed in the inner space and delimited by a pilot portion of the diffuser wall, forming a pilot perforation, and by a pilot wall extended into the inner space. The pilot chamber forms pilot inlet openings supplying air/gas-air pre-mixture into the pilot chamber. A pilot gas opening supplies non-premixed fuel gas into the pilot chamber. A main chamber formed in the inner space is delimited by a diffuser wall main portion, forming a main perforation, and by the pilot wall. The main chamber delimits a main inner volume and is in flow communication with the inlet passageway to supply air/gas-air pre-mixture.

A burner assembly having a blower housing, a blower to supply air to the burner assembly, a blast tube having a longitudinal axis, a fuel source to supply fuel to the burner assembly, a center tube that is substantially parallel to the longitudinal axis and conveys air and fuel to a center tube burner end opening, a plurality of premix tubes, each of which is substantially parallel to the longitudinal axis and conveys air and fuel to a premix tube burner end opening, a diffuser that is disposed in the center tube near the center tube burner end opening, a nozzle that is disposed in the center tube substantially perpendicular to the diffuser. The center tube air and fuel mixture is fuel rich and the premix tubes air and fuel mixture is fuel lean. A method for burning the center tube air and fuel mixture and the premix tubes mixtures.

A burner assembly having a blower housing, a blower to supply air to the burner assembly, a blast tube having a longitudinal axis, a fuel source to supply fuel to the burner assembly, a center tube that is substantially parallel to the longitudinal axis and conveys air and fuel to a center tube burner end opening, a plurality of premix tubes, each of which is substantially parallel to the longitudinal axis and conveys air and fuel to a premix tube burner end opening, a diffuser that is disposed in the center tube near the center tube burner end opening, a nozzle that is disposed in the center tube substantially perpendicular to the diffuser. The center tube air and fuel mixture is fuel rich and the premix tubes air and fuel mixture is fuel lean. A method for burning the center tube air and fuel mixture and the premix tubes mixtures.

A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.

A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.