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Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional POPs PART III Annexes |
Annex 36 Complementary information to source category 4b Lime Production
Overview of recent revisions
The emission factors for this source category have not been revised or otherwise changed. Additional guidance has been introduced on classifying sources within this category, estimating activity rates, and on data quality aspects.
Derivation of emission factors
Release to Air
Emissions have been measured from a number of German kilns (SCEP 1994). An emission factor of 0.07 μg TEQ/t of lime produced is to be used where lime kilns are well controlled and fitted with dust abatement equipment (typically electrostatic precipitator or fabric filter).
However, individual plants found in Europe (3 kilns, 2 rotary kilns and 1 shaft kiln in Sweden n the years between 1989 and 1993) showed measured concentrations between 4.1 and 42 ng N-TEQ/Nm³. All measurements of high PCDD/PCDF emissions were explained either by the raw material and/or fuel content, or the less than optimum burning conditions, underlining the importance of controlling the kiln inputs and maintaining a stable kiln operation (BREF 2010). Considerably higher emissions were also quoted for limited tests (LUA 1997), and an emission factor of 10 μg TEQ/t of lime produced is to be applied where control of the kilns is limited and dust control is basic (cyclone) or absent.
Raw materials or fuels that contain chlorides may potentially cause the formation of PCDD/PCDF in the combustion process of the lime kiln. Data reported from Europe, obtained from seven kilns, of which four were rotary kilns and three were shaft kilns, showed PCDD/PCDF concentrations below 0.1 ng TEQ/Nm³. Measurements at two annular shaft kilns in Germany were all below 0.05 ng TEQ/Nm³. However, the scarcity of measurements means it cannot be ruled out that individual plants may be found in Europe and elsewhere, which may have a local impact (LUA 1997).
High concentrations of PCDD/PCDF have been measured at three kilns, 2 rotary kilns and one shaft kiln, in Sweden. The measurements made between 1989 and 1993 gave concentrations between 4.1 and 42 ng N-TEQ/Nm³. All measurements of high PCDD/PCDF concentration have been explained either by the raw material and/or fuel content, or the less than optimum burning conditions, underlining the importance of controlling the kiln inputs and maintaining a stable kiln operation (BREF 2010).
Release to Water
No release to water is expected. Any effluent identified should be recorded and its source in the process identified.
Release to Land
Lime product or gas cleaning residues may be used on land. No information was available on levels of PCDD/PCDF in these to allow an estimate to be made of releases to land.
Release in Products
No information was available on PCDD/PCDF in lime products. Levels are expected to be low due to the high temperatures used in processing.
Release in Residues
A residue in the form of dust from gas cleaning operations may arise although this may be reused in the process or may have a product value. No information was available on PCDD/PCDF in such dust.
