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.

Liner device, adapted to be mounted between a burner box and a tube interface plate of a furnace. The liner device includes a base section, one or more tube sections, and one or more angle fasteners. The base section includes a shielding layer formed from a first flexible mesh of flame-resistant fibers, the shielding layer defining a first surface that is configured to face the burner box, a second surface opposite to the first surface, and a medial region with a through-hole forming a passageway through the shielding layer. The tube section is composed essentially of a second flexible mesh of flame-resistant fibers formed into a tubular shape that defines an internal channel around a nominal axis. A proximal end of the tube section is positioned at the base section, such that the channel opens into the through-hole and that the tube section projects from the second surface and in a direction faced by the second surface. The angle fastener has a base portion that is positioned along and fixed to the second surface of the shielding layer. The angle fastener further has a leg portion that projects towards the second direction and is positioned along and fixed to an outer surface of the tube section at or near the proximal end thereof.

Liner device, adapted to be mounted between a burner box and a tube interface plate of a furnace. The liner device includes a base section, one or more tube sections, and one or more angle fasteners. The base section includes a shielding layer formed from a first flexible mesh of flame-resistant fibers, the shielding layer defining a first surface that is configured to face the burner box, a second surface opposite to the first surface, and a medial region with a through-hole forming a passageway through the shielding layer. The tube section is composed essentially of a second flexible mesh of flame-resistant fibers formed into a tubular shape that defines an internal channel around a nominal axis. A proximal end of the tube section is positioned at the base section, such that the channel opens into the through-hole and that the tube section projects from the second surface and in a direction faced by the second surface. The angle fastener has a base portion that is positioned along and fixed to the second surface of the shielding layer. The angle fastener further has a leg portion that projects towards the second direction and is positioned along and fixed to an outer surface of the tube section at or near the proximal end thereof.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

A swirler apparatus for a combustor, including: primary and secondary swirlers disposed axially adjacent to each other along a swirler centerline; the primary swirler including a plurality of primary swirl vanes arrayed around the swirler centerline, each primary swirl vane including opposed sides bounded between opposed forward and aft edges and opposed leading and trailing edges; wherein the forward edge is oriented at a first vane angle with respect to a radial direction; wherein the aft edge is oriented at a second vane angle with respect to the radial direction; wherein the second vane angle is different from the first vane angle; and the secondary swirler including a plurality of secondary swirl vanes arrayed around the swirler centerline.

A swirler apparatus for a combustor, including: primary and secondary swirlers disposed axially adjacent to each other along a swirler centerline; the primary swirler including a plurality of primary swirl vanes arrayed around the swirler centerline, each primary swirl vane including opposed sides bounded between opposed forward and aft edges and opposed leading and trailing edges; wherein the forward edge is oriented at a first vane angle with respect to a radial direction; wherein the aft edge is oriented at a second vane angle with respect to the radial direction; wherein the second vane angle is different from the first vane angle; and the secondary swirler including a plurality of secondary swirl vanes arrayed around the swirler centerline.

A swirler apparatus for a combustor, including: primary and secondary swirlers disposed axially adjacent to each other along a swirler centerline; the primary swirler including a plurality of primary swirl vanes arrayed around the swirler centerline; and the secondary swirler including a plurality of secondary swirl vanes arrayed around the swirler centerline, each secondary swirl vane including opposed sides bounded between opposed forward and aft edges and opposed leading and trailing edges; wherein the forward edge is oriented at a first vane angle with respect to a radial direction; wherein the aft edge is oriented at a second vane angle with respect to the radial direction; and wherein the second vane angle is different from the first vane angle.

A swirler apparatus for a combustor, including: primary and secondary swirlers disposed axially adjacent to each other along a swirler centerline; the primary swirler including a plurality of primary swirl vanes arrayed around the swirler centerline; and the secondary swirler including a plurality of secondary swirl vanes arrayed around the swirler centerline, each secondary swirl vane including opposed sides bounded between opposed forward and aft edges and opposed leading and trailing edges; wherein the forward edge is oriented at a first vane angle with respect to a radial direction; wherein the aft edge is oriented at a second vane angle with respect to the radial direction; and wherein the second vane angle is different from the first vane angle.