Dioxin removal/reduction by ADIOX^® in wet scrubber

Objective

Dioxin release is a very serious issue, both with regard to the direct threat to nature and mankind, but also in terms of human psychology and the attitude to the specific industry. The ADIOX^® technology is an efficient, safe and cost-effective technology for removing dioxin from gases.
ADIOX^® is suitable for installation in wet scrubber systems or in other types of containers in a gas cleaning system and at thermal treatment plants for:

Municipal solid waste
Hazardous/chemical waste, especially chloride-based waste
Sludge
Biomass
Steel and metal

Client benefits

Very simple installation of the purpose is to prevent dioxin release by the "memory effect" (described below)
The equipment can be sized for a specific dioxin removal efficiency
Very high availability due to the static absorber technology
Long replacement intervals
ADIOX^® can be integrated in traditional packed bed scrubber systems, thereby cost-effective
No residue product - the ADIOX^® material can be incinerated
Often economically very competitive.

General concept of ADIOX^®dioxin removal

The ADIOX^® technology separates dioxins from gases through absorption/adsorption in a polymer material. The material consists of polypropylene doped with carbon particles. The process has been developed in co-operation with Forschungszentrum Karlsruhe. Götaverken Miljö has the global rights to market and sell ADIOX^®. ADIOX^® is produced and implemented in the form of tower packings and droplet separators and with the traditional additional advantages of these. Subsequently it is installed in wet scrubbers but also in dedicated dioxin removal absorbers operating in a saturated (semi-wet) or dry gas atmosphere.

Products

ADIOX^® for dioxin removal is now introduced into the market as different types of tower packings (Telpac or Rauschert Hiflow of various sizes) or as droplet separators (demisters) of the knitted mesh type (Begg Cousland) or the lamella type (Lechler).

The material is supplied as bulk material to end users for installation in existing wet scrubber and as absorber installations in the form of package units to new flue gas treatment plants or to limited extensions.

The package units are also offered to companies in the position as main contractors in connection with the supply of complete incineration plants or flue gas treatment systems.

The material is installed in different types of applications as follows:

ADIOX^® in wet scrubber (ändrad rubrik, tidigare: Wet ADIOX scrubber)

Normally tower packing material is used in a wet scrubber system to increase the contact surface between the gas and process liquid. The separation of acid components, predominantly hydrochloric acid (HCl) and sulphur dioxide (SO₂) is in that way improved. By manufacturing the tower packing structure in ADIOX^® material, dioxin can be absorbed simultaneously. Also the droplet separators are med of ADIOX^® material.

Semi-wet (moisture saturated) ADIOX^®-absorber
ADIOX^® tower packings can also be installed separately in an absorber, typically placed immediately after a wet scrubber system, where the flue gas still is moisture saturated. From a dioxin removal point of view this is advantageous compared to the installation in a scrubber. The absorption capability is improved and the installation of a demister (droplet separator) and an expensive liquid circulation system will be unnecessary. Consequently the installation will be more compact.

Dry ADIOX^®-absorber
The dioxin removal efficiency in ADIOX^® material is much better when the gas is overheated, typically after a reheater. If the wet gas is reheated approximately 20^oC, the process is optimised and the investment cost for the dioxin removal system will be minimised. The geometry and the location of the dry absorber can be adjusted to prevailing conditions.

ADIOX^®tower packings as bulk delivery
ADIOX^® has been supplied to a large number of reference plants as tower packing material in order to improve the dioxin removal and to minimise the "memory effect" at existing flue gas cleaning plants. We offer ADIOX^® tower packings in various structures of type Rauschert or Mouvitekniikka.

ADIOX^®demisters
Most of existing wet scrubber systems have been equipped with demisters.These are normally constructed of polypropylene (PP) and therefore form a source for the so called "memory effect" (see below). By manufacturing the demisters in ADIOX^® material the risk of exceeding the emission limit values, as a consequence of the memory effect, will be diminished. At the same time the dioxin removal/reduction in the system will be improved. ADIOX^® demisters can be delivered either of "knitted mesh" type (Begg Cousland) or of lamella type (Lechler).

Dimensioning
The requested level of reduction as well as a number of process-technical parametres are dimensioning factors for the amount of ADIOX^® material to be installed. As of August 2009, ADIOX^® of various extent has been installed after approx. 80 incineration lines for mainly municipal and hazardous waste.

With a small amount of packings we have strived to reduce dioxin emissions in the most cost-effective way, alternatively to minimise the memory effect.

ADIOX^® is very suitable for applications where a multifunctional solution is required with integrated separation of HCl, SO₂, HF, Hg and dioxins, in combination with extensive energy recovery through flue gas condensation. In larger installations the dioxin concentration entering the scrubber system can be reduced from a certain level down to well below 0.1 ng/Nm³ TEQ. At Måbjergværket in Holstebro, Denmark, two parallel plants of this type were taken in operation in the autumn of 2004. Also the WTE plants in Malmö (Sysav) and Boden (Bodens Energi) in Sweden have been equipped with this system.

References
Read more about ADIOX^® dioxin removal and memory effect prevention in our reference and product brochures as well as in articles (Press) and Presentations.

Facts about dioxins and dioxin emission

ADIOX^® for dioxin removal - new technology