The use of activated carbon in industrial vapor control systems to store move volatile organic compounds from process and ventilation air streams is very common. This adsorption process is exothermic (liberates heat) and will lead to a temperature rise within the carbon bed. A documented problem in some of these adsorption applications, however, is the formation of an excessive temperature rise that may lead to a thermal runaway in the carbon bed. An excessive temperature rise occurs when the heat of adsorption, plus the heat of reaction of the adsorbed organics exceeds the removal of heat by conductive or convective cooling. Certain compounds, particularly ketones such as Methyl Ethyl Ketone (MEK) or Cyclohexanone are particularly prone to auto oxidation once adsorbed onto activated carbon.
While there are no foolproof methods to guarantee the prevention of carbon bed temperature excursions, Evoqua Water Technologies’ scientists have developed the LoRise process, a patented (US Patent #6,425,941) method to reduce the inherent potential for the excessive liberation of heat in the carbon bed. Through the impregnation of selected activated carbons with Butylated Hydroxytoluene (BHT), an antioxidant and free radical scavenger, the potential for excessive temperature excursions is greatly reduced.