Simultaneous SOx, NOx and Hg~0 Removal in Dry/Semi-Dry FGD Operation

摘要

Discussions/presentations addressing the emerging field of simultaneous removal of NOx in FGD operations invariably relate to wet collectors. They are known to have inherent flexibility in use of diverse chemical processes including methods for simultaneous SO_2/NO_x removal made possible by upstream flue-gas oxidation. Equal or superior in gas cleaning efficiency to wet scrubbing in all respects, dry scrubbers, particularly those employing circulating fluid bed reactors,....with existing, commercial, single-module capacity as great as 330 MW and with 700 MW modules commercially available.....also so function. They can accommodate above integrated gas-cleaning system design with attractive cost effectiveness. Moreover, dry scrubbing augments the performance of any upstream SO_3 abatement/adsorption step by efficiently collecting SO_3/H_2SO_4 (v), and they also avoid need for system conversion to wet stack design and operation. An updated review is given of diverse dry scrubbing based processes, commercial and near commercial, that can achieve extremely low, stack emission rates for multiple pollutants. Typically, they are at the same time particularly apropos in trim service wherein the scrubber, with flue-gas preoxidation system means incorporated, augments the control performance of any/all gas cleaning steps upstream such as primary and secondary deNOx, particulate collection and mercury removal.