The invention provides a combustion apparatus and a combustion method capable of ashing matter to be combusted inside a combustion chamber efficiently without providing a device such as an unburned combustibles measurement device and without varying the direction of injection of air into the combustion chamber. The powder fuel combustion apparatus 1 includes a fuel supply device 10, a primary combustion chamber 20, a secondary combustion chamber 50, an air supply/ash discharge device 32, and a cyclone dust collector 60. An inclined portion 23a is formed at a bottom portion 23 of the primary combustion chamber 20, and the inclined portion 23a includes bottom portion air supply ports 31 and an air supply/ash discharge device 32. The air supply/ash discharge device 32 includes a bottom portion air injection nozzle 34 and an ash delivery device 35. The bottom portion air injection nozzle 34 has upper and lower ends opened, and a plurality of injection ports 34a through which air is injected are formed on a side surface. During combustion of the powder fuel F, air having a strong wind pressure is injected through the bottom portion air injection nozzle 34 either regularly or irregularly to agitate the powder fuel F and achieve a good combustion state.

A method for heating a heating chamber to a temperature below the spontaneous ignition temperature of the fuel that is used, wherein fuel and air are reacted in flameless oxidation in a non-stoichiometric mixture ratio in a combustion chamber. The air ratio λ is at least lower than the stoichiometric ratio λ=1 such that the temperature in the combustion chamber does not exceed the temperature at which thermal nitrous oxide generation begins. Otherwise, λ is established such that the spontaneous ignition temperature of the fuel is exceeded. This results in two permissible air ratio ranges, between λ.sub.min and λ.sub.1 in sub-stoichiometric operation, and λ.sub.2 to λ.sub.max in superstoichiometric operation of the combustion chamber. The still-reactive gases released from the combustion chamber are made to react in the heating chamber, preferably by flameless oxidation. This avoids thermal nitrous oxide generation in the heating chamber.

A reverse-jet swirl pulverized coal burner with multi-stage recirculations includes a pre-combustion housing, a primary coal-air structure, a rich-lean output structure, an inner secondary air structure, and an outer secondary air structure. The pre-combustion housing has a pre-combustion chamber and a housing outlet. The primary coal-air structure is configured to separate a primary coal-air flow into a fuel-rich coal-air flow and a fuel-lean coal-air flow. The rich-lean output structure is configured to output the fuel-lean coal-air flow and block the fuel-rich coal-air flow to make the fuel-rich coal-air flow reversely flow to the pre-combustion chamber. The inner secondary air structure is configured to introduce an inner secondary air into the pre-combustion chamber, thereby forming a first-stage recirculation zone in the pre-combustion chamber and forming a second-stage recirculation zone. The outer secondary air structure is configured to form a third-stage recirculation zone at the housing outlet.

A process and a process plant for production of elemental sulfur from a feedstock gas including from 15 vol % to 100 vol % H2S and a stream of sulfuric acid, the process including a) providing a Claus reaction furnace feed stream with a substoichiometric amount of oxygen, b) directing s to a reaction furnace operating at elevated temperature, c) cooling, d) directing to contact a material catalytically active in the Claus reaction, e) withdrawing a Claus tail gas and elemental sulfur, f) directing to a means for sulfur oxidation, g) directing to contact a material catalytically active in SO2 oxidation to SO3, h) converting to concentrated sulfuric acid, i) recycling to the Claus reaction furnace, wherein an amount of combustibles, in the Claus tail gas, is oxidized in the presence of a material catalytically active in sulfur oxidation, at an inlet temperature below 400° C.

Embodiments of the present invention include high-temperature staged recirculating burners and radiant tube burner assemblies that provide high efficiency, low NOx and CO emissions, and uniform temperature characteristics. One such staged recirculating burner includes a combustion tube having inside and outside helical fins forming opposing spiral pathways for combustion gases and products of combustion, a combustion nozzle coupled to the combustion tube, a gas tube running axially into the combustion tube, and a staging gas nozzle coupled to the gas tube, where the staging gas nozzle includes radial exit holes into the combustion tube and an axial gas staging tube extending into the combustion nozzle to stage combustion.

A process for production of elemental sulfur from a feedstock gas including from 15% to 100 vol % H2S and a stream of sulfuric acid, the process including: a) providing a Claus reaction furnace feed stream substoichiometric oxygen with respect to the Claus reaction, b) directing to a reaction furnace zone operating at elevated temperature such as above 900° C., c) directing to a sulfuric acid evaporation zone downstream said reaction furnace zone, d) cooling to provide a cooled Claus converter feed gas, e) directing to contact a material catalytically active in the Claus reaction, f) withdrawing a Claus tail gas and elemental sulfur, g) directing to a Claus tail gas treatment plant, with the associated benefit of a process involving injection of sulfuric acid in a sulfuric acid evaporation zone allowing high temperature combustion of said feedstock gas, including impurities, without cooling from evaporation and decomposition of sulfuric acid.

A process and a process plant for production of elemental sulfur from a feedstock gas including from 15 vol % to 100 vol % H2S and a stream of sulfuric acid, the process including a) providing a Claus reaction furnace feed stream with a substoichiometric amount of oxygen, b) directing s to a reaction furnace operating at elevated temperature, c) cooling, d) directing to contact a material catalytically active in the Claus reaction, e) withdrawing a Claus tail gas and elemental sulfur, f) directing to a means for sulfur oxidation, g) directing to contact a material catalytically active in SO2 oxidation to SO3, h) converting to concentrated sulfuric acid, i) recycling to the Claus reaction furnace, wherein an amount of combustibles, in the Claus tail gas, is oxidized in the presence of a material catalytically active in sulfur oxidation, at an inlet temperature below 400° C.

A revamp process for modifying a sulfur abatement plant including a Claus process plant, the Claus process plant including a Claus reaction furnace and one or more Claus conversion stages, each Claus conversion stage including a conversion reactor and a means for elemental sulfur condensation, and a means of Claus tail gas oxidation configured for receiving a Claus tail gas from said Claus process plant and configured for providing an oxidized Claus tail gas, the process revamp including: a) providing a sulfuric acid producing tail gas treatment plant producing sulfuric acid, and b) providing a means for transferring an amount or all of the sulfuric acid produced in said sulfuric acid producing tail gas treatment plant to said Claus reaction furnace, wherein the moles of sulfur in the transferred sulfuric acid relative to the moles of elemental sulfur withdrawn from the Claus process plant is from 3% to 25%.

A combustion system such as a furnace or boiler includes a perforated reaction holder configured to hold a combustion reaction that produces very low oxides of nitrogen (NOx).

A burner includes a distal flame holder, first and second fuel nozzles, a fuel and oxidant source, and a mixing tube disposed upstream from the distal flame holder. Fuel emitted from the first fuel nozzle mixes with oxidant from the oxidant source to form a fuel and oxidant mixture to support combustion in the distal flame holder. A non-reactive fluid source such as recirculated flue gas provides a non-reactive fluid for dilution of the fuel and oxidant mixture to prevent flashback.