US 12,435,872 B2 · High efficiency low NOx burner

Abstract

A burner having an air intake, a premix manifold, a blast tube, a rich fuel manifold, and a pilot. The blast tube includes a diffuser, an auxiliary passage, and a shutter. The shutter has at least an open position allowing air and fuel mixtures to flow through the auxiliary passage and the diffuser, and a closed position allowing flow through only the diffuser. Air moves from the air intake to the premix manifold where it mixes with a first fuel. The mixture moves through the blast tube and is ignited by the pilot, forming a lean center flame. A second fuel moves through the rich fuel manifold and ignites via the lean center flame, forming a rich secondary flame. The lean center flame and rich secondary flame combine to form a first flame.

Claims20

Dependent claims

A blast tube comprising:

an external wall creating a hollow interior;
an inlet end;
a blast end;
a diffuser disposed within the hollow interior proximate the blast end and having a primary passage configured to allow fluids to pass through the diffuser;
an auxiliary passage disposed radially between the diffuser and the external wall;
and
a shutter that is disposed within the hollow interior and is configured to be selectively moved between a plurality of selectable positions, including a first position and a second position,
wherein, when the shutter is in the first position, the primary passage and auxiliary passage are both open such that a fluid is permitted to flow through both the primary passage and auxiliary passage, and
wherein, when the shutter is in the second position, the primary passage is open but the auxiliary passage is closed such that the fluid is permitted to flow exclusively through the primary passage.

6 more elements

A method of operating a burner to produce a low NOx flame, the method comprising:

providing a burner comprising:
an air intake having an inlet and an outlet;
a windbox configured to alter a flow characteristic of air, the windbox fluidly connected to and disposed downstream of the air intake such that air from the outlet of the air intake flows into the windbox;
a premix manifold disposed downstream of the windbox and configured to mix fuel and air to form a premixed air/fuel mixture, the premix manifold having:
an internal cavity created by an inner wall;
a first fuel channel;
a plurality of fuel orifices connected to the first fuel channel and disposed radially in the inner wall and configured to allow a first fuel to pass from the first fuel channel into the internal cavity;
and
a first fuel inlet configured to provide the first fuel to the first fuel channel,
a blast tube having the inlet end disposed proximate a downstream end of the premix manifold, the blast tube having:
an external wall creating a hollow interior;
an inlet end;
a blast end;
a diffuser disposed within the hollow interior proximate the blast end and having a primary passage configured to allow fluids to pass through the diffuser;
an auxiliary passage disposed radially between the diffuser and the external wall;
and
a shutter that is disposed within the hollow interior and is configured to be selectively moved between a plurality of selectable positions, including a first position and a second position;
a rich fuel manifold disposed radially about the blast end having:
a central void disposed at the blast end,
a second fuel channel;
a plurality of fuel nozzles fluidly connected to the second fuel channel and disposed radially about the central void on a front wall and configured to allow a second fuel to pass from the second fuel channel and through the front wall;
and
a second fuel inlet configured to provide the second fuel to the second fuel channel, and
a pilot;
passing air into the windbox via the air intake;
receiving the air from the windbox with the premix manifold;
providing the first fuel to the fuel channel of the premix manifold and then moving the first fuel through the plurality of fuel orifices and into the internal cavity;
in the premix manifold, mixing the first fuel with the air to create a premixed air/fuel mixture;
providing the premixed air/fuel mixture to the blast tube;
with the pilot, igniting the premixed air/fuel mixture at the blast end to create a lean center flame,
providing the second fuel to the rich fuel manifold and then moving the second fuel through the front wall of the second fuel channel via the plurality of fuel nozzles to create a distributed second fuel;
igniting the distributed second fuel using the lean center flame or the pilot to create a rich secondary flame;
mixing the rich secondary flame with the lean center flame to create a first flame;
and
adjusting an amount of first fuel provided or adjusting an amount of the second fuel provided to create a low NOx second flame.

32 more elements

Dependencies are inferred from the claim text.

High efficiency low NOx burner

Life of this patent

High efficiency low NOx burner

Life of this patent

Abstract

Claims20