Annex 17 Complementary information to source category 2b Coke Production
Overview of recent revisions
New PCDD/PCDF data were found for coke production in class 2, with significant differences in values for air emissions, which are now considered more robust than those previously included in the Toolkit. Some new emission factors have also been developed with respect to PCBs and HCB air emissions:
Table III.17.1 PCB emission factors for source category 2b Coke Production
2b Coke Production Emission Factors (µg TEQ/t coke produced) Classification Air Water Land Product Residue 1 No gas cleaning 0.2 2 APC with afterburner/ dust removal 0.002
Table III.17.2 HCB emission factors for source category 2b Coke Production
2b Coke Production Emission Factors (µg/t coke produced) Classification Air Water Land Product Residue 1 No gas cleaning 2 APC with afterburner/ dust removal 0.6
These emission factors are provided with:
- A medium level of confidence for class 2, as emission factors are based on a low data range, they are not based on expert judgment, but are derived from a limited geographical coverage;
- A low level of confidence for class 1, as emission factors are based on extrapolation and expert judgment.
Derivation of emission factors
Release to Air
Emissions to air can occur during charging and discharging of the coal/coke as well as during heating. As there is no gas conducted to a stack, the emission factors are hard to measure and are therefore subject to uncertainty. Emission factors from the 2005 version of the Toolkit were derived from a single publication which was released in 1994 (Bremmer et al. 1994). Two publications from 2009 helped reviewing those emission factors. These publications provide data from plants in Taiwan and China (Wang et al. 2009, Liu et al. 2009). Emission factors from plants which can be regarded as class 2 plants were assessed at 0.0134 and 0.024 µg TEQ/t respectively. This assessment led to a revision of the emission factor for class 2 which is proposed to be set at 0.03 µg TEQ/t. The original emission factor for class 1 is not changed, assuming 99% efficiency for class 2 APC devices.
A new emission factor for PCBs (class 2) is derived from measurements achieved in China (Liu et al. 2009). Assuming the same APC efficiency as for PCDD/PCDF removal, an emission factor for class 1 is proposed as well. The same publication concluded on an emission factor for HCB (0.6 µg/t). This emission factor is assigned to class 2 facilities.
Release to Water
A release to water will occur if effluents from quenching or wet scrubbing are discharged. Two emission factors are given: 0.06 μg TEQ/t for untreated water and 0.006 μg TEQ/t for treated water (assumed to be 90% effective).
Release to Land
No release to land is expected.
Release in Products
Any PCDD/PCDF present in the coke product is expected to pass to other processes. No data were available to estimate these amounts.
Release in Residues
Residues may arise from sludge in water treatment and from any collected solids. No data were available on PCDD/PCDF in the residues.