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 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 process for operating a heater that can be operated with hydrocarbon fuel, especially for a vehicle includes providing a substoichiometric air/fuel mixture in a precombustion chamber (18) for a combustion operation and performing a cold flame combustion in the precombustion chamber (18). The precombustion products forming in the precombustion chamber (18) during the cold flame combustion are supplied to a catalyst arrangement (32) and a partial catalytic oxidation is performed for producing a gas containing hydrogen and carbon monoxide. The gas produced during the partial catalytic oxidation is supplied to a main combustion chamber (34) for producing a hydrogen/carbon monoxide/air mixture. The hydrogen/carbon monoxide/air mixture is burned in the main combustion chamber (34).

A process for operating a heater that can be operated with hydrocarbon fuel, especially for a vehicle includes providing a substoichiometric air/fuel mixture in a precombustion chamber (18) for a combustion operation and performing a cold flame combustion in the precombustion chamber (18). The precombustion products forming in the precombustion chamber (18) during the cold flame combustion are supplied to a catalyst arrangement (32) and a partial catalytic oxidation is performed for producing a gas containing hydrogen and carbon monoxide. The gas produced during the partial catalytic oxidation is supplied to a main combustion chamber (34) for producing a hydrogen/carbon monoxide/air mixture. The hydrogen/carbon monoxide/air mixture is burned in the main combustion chamber (34).

A steam generating system includes a nozzle assembly for pulverized coal and air, the coal nozzle assembly comprises an inner housing (3) for conveying primary air and coal and an outer housing (5) for conveying secondary air to an exit face (13) of a nozzle tip (1), wherein the outer housing (3) and the inner housing (5) are arranged coaxially and limit a channel (15) for the secondary air, wherein the cross-sectional area (A.sub.IH) of the inner housing (3) increases towards the exit face (13) of the nozzle tip (1), wherein the cross-sectional area (A.sub.OH) of the outer housing (5) decreases towards the exit face (13), and wherein bars (11) are located in the inner housing (3) near the exit face (13) that accelerate the velocity of the primary air and coal particles.

A steam generating system includes a nozzle assembly for pulverized coal and air, the coal nozzle assembly comprises an inner housing (3) for conveying primary air and coal and an outer housing (5) for conveying secondary air to an exit face (13) of a nozzle tip (1), wherein the outer housing (3) and the inner housing (5) are arranged coaxially and limit a channel (15) for the secondary air, wherein the cross-sectional area (A.sub.IH) of the inner housing (3) increases towards the exit face (13) of the nozzle tip (1), wherein the cross-sectional area (A.sub.OH) of the outer housing (5) decreases towards the exit face (13), and wherein bars (11) are located in the inner housing (3) near the exit face (13) that accelerate the velocity of the primary air and coal particles.

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.

The ignition characteristics of a fuel are adjusted using a unit which has a distribution zone, a oxidation zone and a conversion zone. Fuel is distributed in the distribution zone having a distribution structure. A portion of the fuel is oxidised in the oxidation zone with a oxidising agent on a catalyst on a catalyst carrier, and a portion of the distributed fuel and/or of another supplied fuel is thermally and/or catalytically converted in the conversion zone. The ignition characteristics of the fuel are adjusted via: the molar ratio of oxygen included in the oxidising agent to the oxygen required for the complete oxidation of the fuel provided; and/or via the pressure in the unit; and/or the dwell time; and/or the temperature. Exhaust emissions, in particular NOx and soot emissions, can be lowered.

The ignition characteristics of a fuel are adjusted using a unit which has a distribution zone, a oxidation zone and a conversion zone. Fuel is distributed in the distribution zone having a distribution structure. A portion of the fuel is oxidised in the oxidation zone with a oxidising agent on a catalyst on a catalyst carrier, and a portion of the distributed fuel and/or of another supplied fuel is thermally and/or catalytically converted in the conversion zone. The ignition characteristics of the fuel are adjusted via: the molar ratio of oxygen included in the oxidising agent to the oxygen required for the complete oxidation of the fuel provided; and/or via the pressure in the unit; and/or the dwell time; and/or the temperature. Exhaust emissions, in particular NOx and soot emissions, can be lowered.

A burner system for a cooking device has at least one burner surface wherein the at least one burner surface is designed in such a way that the burner system has a low minimum power density with homogeneous temperature distribution at the same time. In a first aspect, the burner system includes a fuel supply and a first burner surface for burning the fuel that is provided downstream of the fuel supply. The burner system includes a second burner surface for afterburning that is separate from the first burner surface and is provided downstream from the first burner surface. Moreover, a method for operating the burner system is shown.