Division 8.5 Techniques to reduce emissions to air of dust, metals including mercury, and/or PCDD/F
United Kingdom
| Technique | Description |
|---|---|
| Bag filter | Bag or fabric filters are constructed from porous woven or felted fabric through which gases are passed to remove particles. The use of a bag filter requires the selection of a fabric suitable for the characteristics of the flue-gas and the maximum operating temperature. |
| Boiler sorbent injection (in-furnace or in-bed) | See general description in Section 8.4. There are co-benefits in the form of dust and metal emissions reduction. |
| Carbon sorbent (e.g. activated carbon or halogenated activated carbon) injection in the flue-gas | Mercury and/or PCDD/F adsorption by carbon sorbents, such as (halogenated) activated carbon, with or without chemical treatment. The sorbent injection system can be enhanced by the addition of a supplementary bag filter. |
| Dry or semi-dry FGD system | See general description of each technique (i.e. spray dry absorber (SDA), duct sorben injection (DSI), circulating fluidised bed (CFB) dry scrubber) in Section 8.4. There are co-benefits in the form of dust and metal emissions reduction. |
| Electrostatic precipitator (ESP) | Electrostatic precipitators operate such that particles are charged and separated under the influence of an electrical field. Electrostatic precipitators are capable of operating under a wide range of conditions. The abatement efficiency typically depends on the number of fields, the residence time (size), catalyst properties, and upstream particle removal devices. ESPs generally include between two and five fields. The most modern (high-performance) ESPs have up to seven fields. |
| Fuel choice | The use of a fuel with a low ash or metals (e.g. mercury) content. |
| Multicyclones | Set of dust control systems, based on centrifugal force, whereby particles are separated from the carrier gas, assembled in one or several enclosures. |
| Use of halogenated additives in the fuel or injected in the furnace | Addition of halogen compounds (e.g. brominated additives) into the furnace to oxidise elemental mercury into soluble or particulate species, thereby enhancing mercury removal in downstream abatement systems. |
| Wet flue-gas desulphurisation (wet FGD) | See general description in Section 8.4. There are co-benefits in the form of dust and metals emission reduction. |