Dioxins are among the most toxic substances known to man, and they can be formed when incinerating waste. Accordingly, the authorities place extremely stringent demands for low emissions.
Babcock & Wilcox Vølund AB has technologies for the removal of dioxins from flue gas, and for reducing the formation of dioxins. The methods for removal are well established and documented from a great number of installations. We can not only provide dioxin removal using our ADIOX ® technology, but also conventional baghouse filters with carbon dosing.
- ADIOX® is delivered as tower packing or droplet separators in a large range of types and sizes for installation in existing flue gas cleaning installations.
- ADIOX® scrubbers and absorbers, customized for desired removal efficiency and pressure drop.
- Dioxin is removed in baghouse filters with carbon dosing.
Information about dioxin removal (products, services and general information):
INFORMATION ABOUT DIOXINS AND DIOXIN EMISSIONS
Dioxins, or polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), belong to a group of extremely toxic organic substances that are difficult to break down. Dioxins are very stable and they accumulate in the food chain.
Dioxin concentrations are usually expressed in toxic equivalents (TEQs), which are the sum of the toxic congener concentrations multiplied by their specific TEQ factor. The extreme toxicity of 2,3,7,8-Tetra-CDD (aka Seveso dioxin) is used as a reference with a TEQ factor of 1. Dioxins and furans that include a higher number of chlorine atoms (including the 2, 3, 7 and 8-positions) have lower TEQ factors. In 1997, the World Health Organization (WHO) established that 2,3,7,8 TCDD is a human carcinogen.
Major emissions sources are installations for waste incineration, metal production, the combustion of biomass and uncontrolled fires at e.g. landfills. The EU directive stipulates that the emission level to atmosphere be lower than 0.1 ng TEQ/Nm3. In the past, dioxin emissions have been used as an argument against waste incineration, but in actual fact waste incineration only contributes a minor proportion of total atmospheric emissions. The current EU prohibition against the dumping of combustible materials and the increase in waste incineration that has resulted, reduces the risk of landfill fires, which present a much greater potential risk of very large diffuse emissions. Dioxins are destroyed practically in their entirety in stable incineration, but reform through de novo synthesis during flue gas cooling and dust removal in the 200-450°C temperature range. The net effect is a dioxin drop as more dioxins are destroyed than synthesized de novo.
A number of technologies are in use today to destroy or remove dioxins from flue gas in wet or dry applications. Götaverken Miljö provides a method, ADIOX®, of capturing dioxin molecules and preventing emissions caused by the so-called memory effect.