Flue gas purificn. system downstream of refuse incinerator - has acid treatment stage receiving sodium hydroxide to form pure sodium chloride which recycled to mixer stage

摘要

The scrubbing circuits of a flue gas purifcn. system downstream of a refuse incinerator are effected in a first stage with an acid and in a second stage in a neutral to alkaline absorption medium. The acid stage receives an addition of NaOH to form NaCl. The run-off of the acid stage is mixed with Ca(OH)2 to form CaCl2 in a mixer stage. The soln. produced in the mixer stage is merged with the run-off of the second stage in a sulphate pptn. stage. A part of the mother liquor from the NaCl crystallisate sepn. stage is recycled to the mixer stage. ADVANTAGE - This minimises the make of waste water and produces NaCl of adequate purity for re-utilisation.