Disclosed are a combustor for fuel combustion and a combustion method therefor. The combustor includes a primary oxidant-fuel delivery assembly, a secondary oxidant delivery assembly, and a tertiary oxidant delivery assembly. The secondary oxidant delivery assembly and the tertiary oxidant delivery assembly are provided on the same side of the primary oxidant-fuel delivery assembly, and the secondary oxidant delivery assembly is located between the tertiary oxidant delivery assembly and the primary oxidant-fuel delivery assembly. The present invention combines the staged combustion and dilution combustion technologies, such that the combustor has a wide flame adjusting range, realizing adjustment of the flame combustion position, flame speed range, flame local atmosphere and flame length, effectively reducing the generation of NOx, and also achieving high heat transfer efficiency.

A method for heating a furnace with a longitudinal direction and a cross plane which is perpendicular to the longitudinal direction, which furnace includes at least one heating zone heated using combustion of a fuel with an oxidant, and which furnace is further arranged with a dark zone downstream of said heated zone, to which dark zone no fuel is supplied directly. Wherein the fuel and oxidant supplied to the heating zone is substoichiometric, in that between 10% and 40% of the total oxidant for achieving stoichiometric or near stoichiometric combustion is supplied directly to the dark zone, a flue gas temperature is measured in and/or downstream of the dark zone, and the share of the total oxidant supplied to the dark zone is controlled so as not to exceed a predetermined maximum measured such temperature. The invention further relates to a method for retrofitting an existing furnace, and a furnace.

Described herein are two-stage catalytic heating systems and methods of operating thereof. A system comprises a first-stage catalytic reactor and a second-stage catalytic reactor, configured to operate in sequence and at different operating conditions, For example, the first-stage catalytic reactor is supplied with fuel and oxidant at fuel-rich conditions. The first-stage catalytic reactor generates syngas. The syngas is flown into the second-stage catalytic reactor together with some additional oxidant. The second-stage catalytic reactor operates at fuel-lean conditions and generates exhaust. Splitting the overall fuel oxidation process between the two catalytic reactors allows operating these reactors away from the stoichiometric fuel-oxidant ratio and avoiding excessive temperatures in these reactors. As a result, fewer pollutants are generated during the operation of two-stage catalytic heating systems. For example, the temperatures are maintained below 1.000° C. at all oxidation stages.

A thermophotovoltaic generator incorporating a two-stage combustor for providing heat to a thermophotovoltaic cell. Combustor parts include a partial oxidation reactor, which functions catalytically to convert a hydrocarbon fuel and a first supply of an oxidant into a gaseous partial oxidation product; and further include downstream thereof, a deep oxidation reactor including a premixer plenum fluidly connected to a heat spreader comprising a porous matrix, such as a ceramic foam. Functionally, the deep oxidation reactor converts the gaseous partial oxidation product and a second supply of oxidant into complete combustion products. Heat produced by the two-stage combustor generates radiative energy from a photon emitter, which is directly converted to electricity in a photovoltaic diode cell.

A burner and methods of using the burner. The burner produces a flame from combustion air and fuel gas. Flue gas, also produced, can be withdrawn and recycled to the burner. A cooling or condition gas, such as ambient air, may be mixed with the flue gas to reduce its temperature. The burner may also utilize a stage injection so that a portion of the produced flue gas is recycled internally.

An improved and high capacity gas igniter for furnaces and burners. The igniter can include an igniter tip that is annular in shape and includes various holes of different sizes and angular projections distributed throughout. The igniter tip may utilize a slip-joint-like mechanism or sleeve that connects inner and outer tubes of a guide tube that allows the inner tube to slide when undergoing thermal expansion. This configuration alleviates stress from building up on the inner tube and igniter tip, preventing damage.

Emissions of NO.sub.X and/or CO are reduced at the stack by systems and methods wherein a primary fuel is thoroughly mixed with a specific range of excess combustion air. The primary fuel-air mixture is then discharged and anchored within a combustion chamber of a burner. Further, the systems and methods provide for dynamically controlling NO.sub.X content in emissions from a furnace by adjusting the flow of primary fuel and of a secondary stage fuel, and in some cases controlling the amount or placement of combustion air into the furnace.

A thermophotovoltaic generator incorporating a two-stage combustor for providing heat to a thermophotovoltaic cell. Combustor parts include a partial oxidation reactor, which functions catalytically to convert a hydrocarbon fuel and a first supply of an oxidant into a gaseous partial oxidation product; and further include downstream thereof, a deep oxidation reactor including a premixer plenum fluidly connected to a heat spreader comprising a porous matrix, such as a ceramic foam. Functionally, the deep oxidation reactor converts the gaseous partial oxidation product and a second supply of oxidant into complete combustion products. Heat produced by the two-stage combustor generates radiative energy from a photon emitter, which is directly converted to electricity in a photovoltaic diode cell.

Various implementations include a combustor system including an inner wall, a fuel grate, an ash grinder, an igniter, and a fan. The inner wall defines a combustion chamber and has a longitudinal axis and first and second ends. The inner wall defines primary and secondary air inlets. The primary air inlets are defined closer than the secondary air inlets to the first end. The fuel grate is disposed within the combustion chamber between the primary and secondary air inlets and is configured to support fuel disposed within the combustion chamber. The ash grinder is disposed between the fuel grate and the secondary air inlets and is rotatable about the longitudinal axis relative to the fuel grate. The igniter provides energy to the combustion chamber. The fan is configured to cause air to flow from the primary and secondary air inlets through the second end of the combustion chamber.

Emissions of NO.sub.X and/or CO are reduced at the stack by systems and methods wherein a primary fuel is thoroughly mixed with a specific range of excess combustion air. The primary fuel-air mixture is then discharged and anchored within a combustion chamber of a burner. Further, the systems and methods provide for dynamically controlling NO.sub.X content in emissions from a furnace by adjusting the flow of primary fuel and of a secondary stage fuel, and in some cases controlling the amount or placement of combustion air into the furnace.