Separation of Dust, Halogen and PCDD/F in a Compact Wet Scrubber

Abstract

Up-to-date exhaust gas cleaning systems of waste incineration plants are highly effective, yet expensive in terms of equipment and other expenses. Aiming at a simpler, but nevertheless effective system, a compact wet scrubber was developed that consists of several venturi scrubbers working in self-priming mode. The venturi scrubbers are located at the bottom of a multistage packed tower. This compact apparatus incorporates several of the steps of a conventional exhaust gas cleaning process, such as dust separation, quench, acid and basic wet cleaning. Therefore, investment and running costs for the gas cleaning process are reduced without any loss of separation efficiency. The design concept and important experimental results of the compact scrubber are reported. The scrubber has been employed at a hazardous waste incineration plant in order to test its applicability under real conditions. The experiments were used to identify benefits and drawbacks of the scrubber, and to improve the scrubber design concept. It is shown that the developed scrubber is highly effective in separating fine dust particles and inorganic-gaseous pollutants (HCl, HF, SO2). Additionally, the concentration of polychlorinated dioxins and furans (PCDD/F) is significantly reduced in the off-gas of the scrubber. These compounds are adsorbed into plastic packing materials.