Air pollution control process and apparatus

Claim 1

Method of removal of SO x and fly ash particulates from hot flue gases comprising: (a) passing said hot flue gases through a flue gases pretreatment and waste products dry collection zone; (b) introducing an aqueous reaction products liquor containing ammonium or sodium sulfur oxide salts and at least a portion of said fly ash in a slurry form into said hot flue gases in a first portion of said pretreatment-dry collection zone in a finely divided condition and at a solids content sufficient to permit evaporation of substantially all of the water content of said liquor and produce dried particles of ammonium and sodium sulfur oxide salts; (c) removing a first, major portion of said dried salts particles in association with fly ash in a second portion of said pretreatment-dry collection zone to produce a partially cleaned flue gas containing a minor portion of said dried salts particles, and said fly ash; (d) introducing said partially cleaned flue gas containing said fly ash into a reaction zone; (e) contacting said partially cleaned flue gas containing said fly ash in said reaction zone with an aqueous ammonium or sodium alkali SO x sorbent liquor selected from NH 4 OH, (NH 4 ) 2 CO 3 , NH 4 HCO 3 , NaOH, Na 2 CO 3 , NaHCO 3 and mixtures thereof for a time sufficient: (i) to react SO 2 and SO 3 in said partially cleaned flue gas therewith to form said reaction products liquor and fly ash slurry; (ii) to collect dried salts particles and said fly ash from said partially cleaned flue gas, and (iii) to form substantially clean flue gas; (f) exhausting said clean flue gas from said reaction zone; and (g) passing reaction product liquor containing at least a portion of said fly ash in slurry form from said reaction zone to said pretreatment-dry collection zone.