Abstract: A nozzle in a descending discharge duct for hot flue gases has a tubular body of hourglass shape partly obstructed by a vertically movable frustoconical insert which defines a narrow, downwardly diverging annular channel with the lower part of the body lying below its waist. The upwardly converging top of the insert, projecting partly above the waist, is coated or clad with a refractory layer and is removable for replacement of that layer.

Abstract: The gas-cleaning apparatus for a blast furnace operating under pressure using a differential-pressure washing arrangement whereby the differential-pressure washer comprises at least one annular gap with an annular-gap passage and an axially adjustable body received in the annular gap washer. The nozzle is disposed upstream of the annular-gap washer to spray the washing liquid into the gas which is accelerated through the annular gap. The position of this body is controlled in response to the gas pressure within the head of the blast furnace. The annular gap of the washer diverges in the direction of flow of the gas and the body has a complementary shape so that the gap width remains generally constant although its flow cross section increases with the diameter of the annular gap in the direction of flow of the gas.

Abstract: Stack gas is first passed through a coarse-particle separator and then a prescrubbing tower. Then this gas, which is under pressure, is passed through a pair of differential-pressure (annular-gap) washers. The output side of one of the washers is connected directly to a droplet separator at the output of the system. The outlet of the other washer is connected through a turbine driving an electric generator and having its output side in turn connected to the droplet separator. The control body of at least the washer which is connected directly to the droplet separator is adjustable so as to maintain a constant backpressure in the system at the blast furnace from which the stack gas comes. The washer connected to the turbine is set up to pass at least four times as much of the gas as the other washers so that most of the gas passes through the turbine, undergoing a pressure drop that is transformed into the work of driving the turbine and generates electricity.

Abstract: An apparatus for cleaning the exhaust gas of a high-pressure blast furnace comprises a coarse-particle separator, a prewasher and a differential-pressure annular gap washer traversed in succession by the gases. The exhaust gases can be passed through a main duct provided with an expansion turbine or through a bypass duct around the expansion turbine. The expansion turbine unit controls the back pressure at the blast furnace while a separate control circuit is provided to operate the differential-pressure washer with optimum efficiency. A quick-closing valve in the turbine-supply line and a quick-opening valve in the bypass line permits rapid switchover, a pressure-control valve in the bypass line maintains a constant backpressure at the blast furnace when the expansion turbine unit is shut down.

Abstract: Waste gas from a coal-fired power plant is scrubbed with a lime-water mixture to form a sludge whose water content is reduced and which is mixed with a binder such as water glass. This mixture is then pelletized to produce hard water-stable material suitable for use as an aggregate or filler. The waste gas may be stripped of its fly ash and this ash added to the sludge to thicken it.

Abstract: An incinerator gas is first passed through an evaporative cooler operating above the dew point of the gas and then the gas is passed through an electrostatic precipitator or cyclone which strips dry particles from the gas. Thereafter the gas passes through a scrubber operating with a scrubbing liquid so as to produce a solution that is fed to a clarifier. The decantate from the clarifier is recirculated as the scrubbing liquid whereas the sludge is neutralized and fed back into the evaporative cooler. Flash evaporation of this neutralized sludge in the cooler causes salt to crystalize so that these crystals can be stripped out at the downstream dry filter. A valve body at the outlet side of the scrubber is positioned in accordance with gas pressure inside the incinerator so as to maintain back pressure within the system substantially uniform.

Abstract: A nonferrous metal is heated so as to produce a hot gas that is passed through an evaporative-cooler and, without saturation of the gas, is introduced into a dry-process filter where particulate material is removed. Thereafter this gas is fed to a scrubbing tower whose scrubbing liquid removes gaseous, liquid, and any remaining particulate material from the gas and exits from the tower as a scrubbing liquor. This liquor is clarified and the decantate is recirculated for use as the scrubbing liquid while the sludge is neutralized and sent back to the evaporative cooler. The neutralized sludge is flash evaporated in the evaporative cooler so as to form crystals that are removed from the system either in this cooler or at the dry filter downstream therefrom. A particle filter may be provided between the neutralizer and the evaporative cooler to remove any hard particulate material from the neutralized sludge.

Abstract: Stack gas is first passed through a coarse-particle separator and then a prescrubbing tower. Then this gas, which is under pressure, is passed through a pair of Venturi washers. The output side of one of the washers is connected directly to a droplet separator at the output of the system. The outlet of the other Venturi washer is connected through a turbine driving an electric generator and having its output side in turn connected to the droplet separator. The control body of at least the washer which is connected directly to the droplet separator is adjustable so as to maintain a constant back pressure in the system at the blast furnace from which the stack gas comes. The Venturi washer connected to the turbine is set up to pass at least four times as much of the gas as the other Venturi washers so that most of the gas passes through the turbine, undergoing a pressure drop that is transformed into the work of driving the turbine and generates electricity.

Abstract: Sodium carbonate is added to water used to scrub converter gases so that calcium-oxide particles in the gas react with the aqueous sodium carbonate and a thin inactive film of calcium carbonate is formed on the calcium-oxide particles, using carbon dioxide in the gas for the reaction. The coated particles are then separated from the wash water by settling and sedimentation and the wash water is recycled with the addition of more sodium carbonate and water.

Abstract: Dust-laden waste gases from a converter and from ancillary equipment are exhausted by respective blowers through a first and a second duct to a main and a secondary scrubbing station whence the purified gases escape through respective chimneys. The first duct is provided with two cascaded washing stages, the upstream stage being operable to throttle or block the flow of gases therethrough. An annular cowl for the interception of peripherally escaping converter gases is connected to a third duct which joins the first duct at a location between the two washing stages but is also connectable through a switching valve to the second duct.