title: Dry scrubbing of acid gases in recirculating cyclones.
abstract: This paper describes a laboratory-scale study on the use of recirculating cyclones as reaction chambers for dry scrubbing of gaseous HCl with solid slaked lime particles. This gas cleaning system combines a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, which simultaneously increases the capture of the solid particles and promotes their partial recirculation. A laboratory-scale study was undertaken to test this technology and to compare its performance to a modified Stairmand HE reverse flow cyclone without recirculation. The experimental conditions were: reaction temperature approximately 326 K, gas flow rate approximately 2.9 x 10(-4) Nm(3) s(-1) and relative humidity of the gas approximately 8.5%. The experimental variables tested were the solids load (1.0-9.2 x 10(-7) kg s(-1)) and HCl concentration (0.4-2.8 x 10(-2) mol m(-3)) in the inlet gas. The experimentally obtained particulate removal efficiencies with the recirculating cyclones ( approximately 98%) were higher than those obtained with the Stairmand HE cyclone ( approximately 93%), with the additional advantage of having significantly lower pressure drop. As for the acid removal efficiencies ( approximately 10-96%), no significant differences were found between the two systems tested under the same experimental conditions. The possibility of using optimized recirculating cyclones for gas cleaning in a dry scrubbing process is very promising, since this is a low cost technology, highly efficient both for the removal of acid gases and for the capture of solid particles, which has the advantage of not requiring a post-reaction de-duster.
authors.affiliation: DEQ, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Vânia
authors.initials: V
authors.lastname: Chibante
authors.forename: Ana
authors.initials: A
authors.lastname: Fonseca
authors.forename: Romualdo
authors.initials: R
authors.lastname: Salcedo
mesh_terms: D000393:Air Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D000397:Air Pollution / Q000517:prevention & control; D017610:Calcium Compounds / Q000737:chemistry; D005740:Gases / Q000737:chemistry / Q000302:isolation & purification; D006851:Hydrochloric Acid / Q000737:chemistry / Q000302:isolation & purification*; D017745:Incineration / Q000295:instrumentation*; D010087:Oxides / Q000737:chemistry; D018505:Waste Management / Q000295:instrumentation*
chemical_list: D000393:Air Pollutants; D017610:Calcium Compounds; D005740:Gases; D010087:Oxides; C016538:lime; D006851:Hydrochloric Acid