Abstract: Limestone is dried for grinding to very fine particles e.g., about 8.mu. or less with more than 99% of the particle by weight less than 44.mu., by utilizing waste heat from the flue gas from a large combustor. The finely-divided calcium carbonate is then introduced dry into a scrubbing tower where it mixes with and renews the slurry employed therein for scrubbing SO.sub.x -laden effluent.

Abstract: Sulfur oxides (SO.sub.x) are scrubbed from combustion effluents with aqueous limestone slurries with greater efficiency due to the use of an improved entrainment separator. In the preferred embodiment of a single-loop, counter-current limestone wet scrubber operating at bulk gas flow rates of greater than 4.5 meters per second, a vertical stream of flue gas is freed of a substantial portion of slurry droplets and diverted for effective mist removal by a well-drained, horizontal-flow mist eliminator. The entrainment separator is a single-pass device with individual blades aligned for effective operation with reduced droplet impingement on the upper walls (e.g., roof) of the scrubber and to permit periodic washing.

Abstract: Sulfur oxides (SO.sub.x) are scrubbed from combustion effluents with aqueous limestone slurries with greater efficiency and with economies in capital and operating costs. In the preferred embodiment of a single-loop, open-tower countercurrent limestone wet scrubber, effluent flow rates are greatly increased while L/G values and reaction tank residence times are decreased. Improved entrainment eliminator design, novel nozzle placement and spacing, and the use of a hydrocyclone to separate and recycle smaller particles of limestone from the byproduct gypsum, facilitate these advantages. The limestone is reduced to very fine particles, e.g. about 8.mu. or less with more than 99% of the particle by weight less than 44.mu., and introduced into a scrubbing slurry which is contacted with SO.sub.x -laden effluent.

Abstract: Limestone is dried for grinding to very fine particles e.g., about 8.mu. or less with more than 99% of the particle by weight less than 44.mu., by utilizing waste heat from the flue gas from a large combustor. The finely-divided calcium carbonate is then introduced dry into a scrubbing tower where it mixes with and renews the slurry employed therein for scrubbing SO.sub.x -laden effluent.

Abstract: Sulfur oxides (SO.sub.x) are scrubbed from combustion effluents with aqueous limestone slurries with greater efficiency due to the use of an improved entrainment separator. In the preferred embodiment of a single-loop, counter-current limestone wet scrubber operating at bulk gas flow rates of greater than 4.5 meters per second, a vertical stream of flue gas is freed of a substantial portion of slurry droplets and diverted for effective mist removal by a well-drained, horizontal-flow mist eliminator. The entrainment separator is a single-pass device with individual blades aligned for effective operation with reduced droplet impingement on the upper walls (e.g., roof) of the scrubber and to permit periodic washing.

Abstract: Hot flue gas, such as the flue gas from a fossil fuel furnace or a waste incinerator, to be scrubbed to remove acidic gas, such as sulfur dioxide and hydrogen chloride gas, and particulates, such as fly ash, is passed to a primary drying chamber and contacted therein with a spray of droplets of an absorbent liquid containing particles of an alkali or alkaline reactant. The droplets are partially dried in the primary drying chamber to a tacky condition before reaching a foraminous collecting member extending through a lower portion of the primary drying chamber wherein it collects as a moist, porous mat. As the flue gas continues to flow through the mat depositing on the collecting member, the mat serves as a filter for removing particulates, including fly ash, in the gas and the remaining sulfur oxides in the gas react with unreacted particles of reactant and reactive ingredients of the fly ash collected in the mat.

Abstract: A process gas is introduced into a treatment chamber (40) through a horizontal spiral gas supply duct (30) having a tangential inlet (31) and opening to a pair of concentric, inner and outer annular gas inlet ducts (12,22) surrounding a liquid spray apparatus (2). Partition means (32) divide the spiral supply duct (30) into independent inner and outer sub-ducts (34,36) which define separate inner and outer flow passages (44,46) connected respectively to the inner and outer annular gas inlet ducts (12,22). Damper means (70) is provided in the inlet to the outer sub-duct (36) to selectively control the flow of process gas (7) therethrough as a means of maintaining the velocity of the flow of process gas (5) through the inner flow passage (44) above a minimum acceptable velocity.

Abstract: A sonic atomizing spray nozzle (40) wherein a slurry (30) of finely-divided sulfur oxide absorbent particles in a carrier liquid is sprayed into a flue gas stream (12) entering a drying chamber (20) for effecting the removal of sulfur oxides therefrom as a dry salt. The slurry is sprayed through a continuous circumferential slit (70) as a radially outwardly directed thin sheet which traverses an axially-downwardly directed curtain of atomizing gas passing from an annular channel (66) circumscribing and bordering upon the continuous slit (70).