A supercritical CO.sub.2 boiler capable of realizing uniform combustion, corrosion resistance and coking resistance, and a boiler system are provided. The supercritical CO.sub.2 boiler includes a main combustion chamber, an upper furnace, a furnace arch and a flue, wherein a cross section of the main combustion chamber is circular or oval, or is of an N-sided shape, where N>4; at least four burner groups are disposed on the main combustion chamber, each group of burner nozzles corresponding to each burner group includes a recirculating air nozzle, a primary air nozzle and a secondary air nozzle; lateral recirculating air nozzles symmetrically distributed are respectively disposed at two sides of the primary air nozzle, the recirculating air nozzle and the lateral recirculating air nozzle are configured to feed recirculating flue gas or a mixed gas of the recirculating flue gas and secondary air into the main combustion chamber.

The invention relates to a method of making a mineral melt, the method comprising providing a circulating combustion chamber which comprises an upper zone, a lower zone and a base zone, injecting primary particulate fuel and particulate mineral material and primary combustion gas into the upper zone of the circulating combustion chamber, thereby at least partially combusting the primary particulate fuel and thereby melting the particulate mineral material to form a mineral melt and generating exhaust gases, injecting into the lower zone of the circulating combustion chamber, through at least one first burner, secondary combustion gas and gaseous fuel and secondary particulate fuel, wherein the secondary combustion gas and gaseous fuel and secondary particulate fuel are injected via a single first burner, wherein the amount of secondary combustion gas injected via each first burner is insufficient for stoichiometric combustion of the total amount of gaseous fuel and secondary particulate fuel injected via that first burner, and injecting tertiary combustion gas into the lower zone of the circulating combustion chamber, through at least one tertiary combustion gas injector, whereby the tertiary combustion gas enables completion of the combustion of the gaseous fuel and the secondary particulate fuel, separating the mineral melt from the hot exhaust gases so that the hot exhaust gases pass through an outlet in the circulating combustion chamber and the mineral melt collects in the base zone. The invention also relates to apparatus suitable for use in the method.

A gas pipe ignitor for igniting a non-premixed air and fuel mixture includes a housing having an axially interior space along its length, a supply end segment, a flame end segment axially spaced from the supply end segment, and a flexible segment spaced between the supply end segment and the flame end segment. A fuel supply conduit extends axially within the housing, and the fuel supply conduit is operatively flexible with the flexible segment. An ignition conduit extends axially within the housing, and the ignition conduit is operatively flexible with the flexible segment. A detector conduit extends axially within the housing, and the detector conduit is operatively flexible with the flexible segment. An air supply conduit is operatively connected to the housing at the supply end segment and provides combustion air within the interior space.

A supercritical CO.sub.2 boiler capable of realizing uniform combustion, corrosion resistance and coking resistance, and a boiler system are provided. The supercritical CO.sub.2 boiler includes a main combustion chamber, an upper furnace, a furnace arch and a flue, wherein a cross section of the main combustion chamber is circular or oval, or is of an N-sided shape, where N>4; at least four burner groups are disposed on the main combustion chamber, each group of burner nozzles corresponding to each burner group includes a recirculating air nozzle, a primary air nozzle and a secondary air nozzle; lateral recirculating air nozzles symmetrically distributed are respectively disposed at two sides of the primary air nozzle, the recirculating air nozzle and the lateral recirculating air nozzle are configured to feed recirculating flue gas or a mixed gas of the recirculating flue gas and secondary air into the main combustion chamber.

The present invention provides a solid fuel burner which ensures ignition performance and flame holding performance of a fuel nozzle. The present invention provides a solid fuel burner which achieves cost reduction by simplifying the structure of the fuel nozzle, for example, and which ensures the ignition performance and flame holding performance of the fuel nozzle. Further, the present invention provides a burner which enables stable combustion by both solid fuel and oil combustion with the suppression of soot and dust and mist generated during the oil start-up envisaged. The solid fuel burner of the present invention includes: a fuel nozzle straight tube portion allowing a mixing gas of a solid fuel and its carrier gas to flow therethrough; a fuel nozzle throttling portion narrowing a flow passage of the mixing gas passed through the fuel nozzle straight tube portion; a fuel nozzle diffusion portion horizontally expanding the flow passage of the mixing gas passed through the fuel nozzle throttling portion; a fuel nozzle outlet portion connected to the fuel nozzle diffusion portion and having an outlet flattened in shape; a ring-shaped outer peripheral flame stabilizer disposed on an outer periphery of the fuel nozzle outlet portion; and an inner flame stabilizer disposed in the fuel nozzle outlet portion and horizontally dividing the mixing gas passed through the fuel nozzle diffusion portion.

A powder metallurgical component has a chromium content of at least 80% by weight and pores and/or oxide inclusions which are present in the component. The number per unit area of a sum of pores and oxide inclusions at a cut surface through the component in at least one region is at least 10,000 per mm.sup.2.

The present invention relates to an apparatus and a method of making a mineral melt, the method comprising the steps of providing a circulating combustion chamber (1); injecting fuel, preheated mineral material and combustion gas into the circulating combustion chamber (1); combusting the fuel in the circulating combustion chamber (1) thereby melting the mineral material to form a mineral melt and generating exhaust gases; separating the exhaust gases from the mineral melt, collecting the mineral melt (9) and passing the exhaust gases (10) to a heat exchange system, the method being characterised in that the mineral material comprises a first mineral material and a second mineral material wherein the first mineral material has a higher sintering temperature than the second mineral material and the first and second mineral materials are provided separately to the heat exchange system, wherein the first mineral material is preheated through contact with the exhaust gases and subsequently the second mineral material is preheated through contact with the exhaust gases and the preheated first mineral material.

A cylindrical furnace having a vertical axis controls combustion. Solid fuel, particulates, and gases inside the furnace rotate around the axis, inducing radial stratification using centrifugal forces. Fuel and particulates drag on the wall of the cylinder, slipping in and out of suspension, thereby increasing particle residence times. The solid particles comprise combustible fuel particles, and non-combustible ash and contaminants. Control of the temperature of non-combustible particles and the wall surface prevents these non-combustible particles from adhering to, and building up on, the furnace wall. It is also advantageous to control the gas temperature leaving the furnace to minimize temperature-driven corrosion of downstream heat-exchange surfaces. Method and apparatuses are described to control the gas, non-combustible particle, and wall temperatures. The furnace can be integrated into a stand-alone boiler or as a combustor in which a portion of the pyrolysis gas from the combusting fuel is burned in a separate vessel.

A precombustor system (300) including an ignition chamber (301) having a front wall (308), a central axis, a diameter D.sub.ic, and an outlet (313) configured to discharge a product gas (315). The ignition chamber (301) includes a central ignition oxygen injector (307) configured to inject a first oxygen stream from the front wall (308) substantially parallel to the central axis, and a tangential primary fuel injector (303) configured to inject a primary fuel stream tangential to the central axis at a location an axial distance X.sub.pf downstream of the front wall (308). The ratio X.sub.pf/D.sub.ic is from 0.25 to 4.0. The central axis forms an angle a with a vertical line of less than or equal to about 45 degrees. The trajectory of the primary fuel stream forms an angle with a plane that is perpendicular to the central axis of less than or equal to about 20 degrees. A method for combustion is also disclosed.