Removing PAHs from flue gas

Aircon H

Europe is taking the lead in recycling used materials. The construction industry is playing its part too. When resurfacing a tarmac road, the used asphalt is no longer disposed of in landfill sites. It can be recycled as a component in the production of new asphalt.

The used asphalt contains contaminants that evaporate during the recycling process, for example oil and tyre residues. This vapour contains, among other things, PAH's (polycyclic aromatic hydrocarbons), which are carcinogens. The most relevant PAH's are are benzo(a)pyrene, napthalene and anthracene.

In collaboration with Implenia in Switzerland, DESOTEC recently carried out a project which extracts these PAH's from flue gases using activated carbon adsorption. DESOTEC’s engineering team had to deal with some particular challenges: the high temperature of the gas (>100°C), the risk of condensation during standstills, reducing pressure drop despite the high gas flow rate (70,000 m3/h) and the limited space available. Apart from the PAH's, other volatile organic components are also removed from the gas.

Our solution: two temperature-resistant insulated mobile activated carbon filters, type AIRCON-H (see the video).
((c) Implenia Schweiz AG). DESOTEC’s role is shown from minute 2:40 onward in the video.

Not only is the asphalt recycled, but so too is the activated carbon.  It is turned into a reusable product in one of our three reactivation furnaces, while the adsorbed VOCs and PAH's are destroyed in our flue gas cleaning process.