Zero 'dioxin' releases in coal combustion and coal/organic waste co-combustion processes (NoDioxComb)

Basic technological developments aim at indirectly hindering dioxin/furan formation by greatly decreasing free hydrochloric acid and by neutralising catalytic effects of heavy metals swept along inside fly ash-loaded gases at combustor output. Addition of lime, potassium hydroxide and sodium carbonate (10 w %) decreases both dioxins/furans and heavy metals (Cu, Mn, Co, Cr, etc.) during lignite/RDF co-combustion. Gaseous ammonia injected into the raw gases after the combustion bed within a temperature range of 400-450 °C induces a decrease of PCDD/DFs released in flue gases (varying from 50 % to 90 %). Other end-of-pipe processing treatments are targeted to trap multi-pollutants in flue gases. Extruded ceramic composite clay/activated carbon (with AC content of up to 75 w %) can be successfully produced in various geometries (honeycomb, hollow tubes, etc.) and are potential PCDD/DFs adsorbers. Composite bag filters (P84/AC/P84) exhibit good dust filtration efficiency (higher than 99 w %) and high dioxin/furan adsorption capacity (a few hours, depending on the flue gas contamination level). Both of them can be regenerated by PCDD/DFs thermal desorption and destruction into the combustion unit. HyColl industrial technology (> 99.9 % particulate and > 99 % heavy metals collection efficiency) is a suitable best available technology candidate for coal power plants and could be an appropriate and low-cost add-on retrofit technology to existing plants with electrostatic precipitators (HyColl investment is about 50 % of fabric filters investment).