Dry-Scrubbing of Acid Gases in Recirculating Cyclones

• Author(s): Chibante, Vania ; Fonseca, Ana ; Salcedo, Romualdo
• Date: 2007
• Persistent ID: http://hdl.handle.net/10284/294
• Origin: Repositório Institucional - Universidade Fernando Pessoa
• Subject(s): Recirculating cyclones; Gas Cleaning; Dry-scrubbing; HCl; Slaked lime; Cyclone reactor
• Document Type: Article
• Language: English

Description

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 ≈326K, gas flow rate ≈2.9x10-4Nm3.s-1 and relative humidity of the gas ≈8.5%. The experimental variables tested were the solids load (1.0-9.2 x10-7kg.s-1) and HCl concentration (0.4-2.8 x10-2mol.m-3) in the inlet gas. The experimentally obtained particulate removal efficiencies with the recirculating cyclones (≈98%) were higher than those obtained with the Stairmand HE cyclone (≈93%), with the additional advantage of having significantly lower pressure drop. As for the acid removal efficiencies (≈10 to 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.