Risks and prevention in VOC adsorption units

Activated carbon is used extensively as a universal adsorbent for flue gas treatment, eliminating volatile organic compounds (VOCs) and odorous molecules present in industrial gaseous emissions . In France in 2010, activated carbon adsorption plants accounted for around 30-35% of the total number of plants treating VOC-laden gaseous emissions. Generally speaking, these plants take the form of fixed beds lined with grains of activated carbon (virgin or impregnated), through which the air or gas to be treated passes. The transfer of contaminants from the gas phase into the porosity of the carbonaceous material enables the gas to be purified. After saturation, the activated carbon is either placed in a landfill, reactivated in a plant, regenerated in situ by a heat transfer fluid (steam, hot gas) or by intrinsic heating of the material (electrodesorption, for example) . Due to an exothermic reaction occurring during the adsorption reaction, local heating can occur. This temperature rise depends on a number of parameters, such as pollutant concentration, activated carbon type and operating conditions (flow rate, humidity, etc.). This particular phenomenon of exothermicity in adsorption reactions has long been known, but needs to be better understood and understood to avoid incidents such as hot spots, thermal runaway or bed ignitions. The first accident involving the combustion of an activated carbon bed was reported in the 1940s. Ignition of...