Abstract: A rotary heat exchanger surmounts a scrubbing tower provided with two scrubbing columns through which the flue gas of fossil fuel combustion is passed in succession so that the rotary heat storage mass of the regenerative heat exchanger is heated by the incoming flue gas and the flue gas cooled in the scrubbing columns is reheated by the rotary heat storage mass as it leaves the tower.

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: 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.