Annex 12 Complementary information to source category 1d Light Fraction Shredder Waste Incineration
Overview of recent revisions
No revisions were made to emission factors in this source category. Additional guidance has been introduced on classifying sources within this category, estimating activity rates, and on data quality aspects.
Derivation of emission factors
The default emission factors are based on a fly ash generation rate of 3%.
Class 1 includes very simple type combustors such as simple stationary grate furnaces with no combustion controls and no APC equipment attached. Batch type operated furnaces without any APC also fall into class 1.
Class 2 should be chosen for all other furnaces with some kind of combustion control technology such as under and/or over fire air, stoker controls, fluidized beds, etc. including the facilities with some kind of APC system such as an ESP, baghouse or wet scrubber for dust removal.
Class 2 also applies to LFSW incinerators with controlled combustion and adequate APC equipment, which, however, are still operated in a batch type mode. The vast majority of all LFSW incineration plants can be assumed to fall into classes 1 and 2.
Class 3 should only be used for highly sophisticated RDF incineration plants and only, if a regulatory value equivalent to 0.1 ng TEQ/Nm³ (at 11% O2) is enforced, and the facility in question must be assumed to be in compliance.
Release to Air
There are not many measured data from this type of activity. The default emission factor for class 1 was derived based on a emission factor of 1,000 ng TEQ/kg as determined by the US EPA during a barrel burn study of selected combustible household waste which closely resembles the composition of fluff.
Class 2 uses various emission data from a series of Western European and North American RDF facilities including Japanese fluidized bed combustors with minimal APC equipment. An emission factor of 50 µg TEQ/t was determined.
Class 3 represents the current state-of-the-art in LFSW incineration and APC technology. Thus, only 10,000 Nm³/t light-shredder waste and a concentration of less than 0.1 ng TEQ/Nm³ (at 11% O2) is taken. In one study involving the combustion of shredder residue in an advanced incinerator, PCDD/PCDF concentrations in stack gas ranged from 4.93 to 14.82 pg TEQ/Nm³ (11% O2) (Mancini 2010).
Release to Water
Measured PCDD/PCDF concentrations found in scrubber effluent after LFSW incinerators are not available. No emission factor can be provided.
Release to Land
No release to land is expected unless untreated residue is directly placed onto or mixed with soil. The concentration released in such cases will be covered under “Release in Residues”.
Release in Products
The process has no product, thus no release to product occurs.
Release in Residues
PCDD/PCDF concentrations in fly ash must be assumed to be high. The amount of fly ash in LFSW is typically around 3%. In class 1, no APC equipment is used and consequently no fly ash is collected but rather most of it is emitted to the atmosphere with the flue gas. Even though no specific collection device for fly ash is installed and the majority of the fly ash is discharged through the stack, some fly ash is expected to collect in the furnace and the ductwork leading to the stack as well as in the stack itself. Since unburned carbon in the fly ash greatly enhances the adsorption of PCDD/PCDF, the concentration is greatest in class 1. However, no accurate data is available for this class.
Class 3 assumes not only high combustion efficiency but also very high collection efficiency, especially for the very small fly ash particles. Thus, a value of 15,000 ng TEQ/kg ash is chosen. These small particles supply a large adsorption surface for PCDD/PCDF and therefore the overall concentration does not decrease any further (LUA 1997, IFEU 1998). In addition, PCDD/PCDF concentrations reported in fly ash are 98 ng TEQ/kg (boiler) and 27 ng TEQ/kg (bag filter) and 29 ng TEQ/kg in bottom ash (Mancini 2010).