Abstract: A gas cleaning system of the type having a gas cooling tower includes a septum arrangement within the cooling tower which divides the cooling tower into upper and lower chambers and effects a pressure drop between the chambers by directing streams of higher pressure gases through a pool of cooling water maintained in a trough in the septum arrangement to reduce the pressure while simultaneously scrubbing the gases, all within the cooling tower.

Abstract: An improved double alkali process is disclosed which is useful for the removal of sulfur dioxide from gas streams, especially waste gas streams derived from coal-fired plants which also contain entrained fine particles of ash which contain alkali, which process comprises leaching soluble alkali from said entrained fine particles to establish an aqueous alkali scrubbing solution, scrubbing the resulting gas stream with said scrubbing solution, which circulates between said leaching and scrubbing steps, followed by bleeding off a portion of the resulting scrubber effluent to a regeneration system wherein the alkali scrubbing solution is regenerated.

Abstract: An improved apparatus and process are disclosed for the removal of sulfur oxides such as sulfur dioxide from waste gas streams. The process comprises scrubbing the waste gas with a circulating aqueous sodium sulfite/sodium bisulfite absorption solution at a relatively low pH followed by subjecting a portion of the circulating absorption solution to an improved multi-stage regeneration procedure wherein lime is employed to regenerate sulfite from bisulfite. The bleed from the scrubbing step which is subjected to regneration has a low pH and hence can dissolve more lime thereby increasing the lime utilization efficiency. In the regeneration procedure, a lime slurry is separated into a slurry of coarser lime particles and a second portion which contains very fine lime particles. The main regeneration is accomplished by adding the coarse lime slurry to the scrubber bleed. Due to the low pH in this reaction, not all the bisulfite is regenerated to sulfite.