# Commission Implementing Decision of 9 December 2013 establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for the production of chlor-alkali (notified under document C(2013) 8589) (Text with EEA relevance) (2013/732/EU), Division 6: Emissions to air

Extent: E+W+S+N.I.

BAT 8: In order to reduce channelled emissions of chlorine and chlorine dioxide to air from the processing of chlorine, BAT is to design, maintain and operate a chlorine absorption unit that incorporates an appropriate combination of the following features:
(i) absorption unit based on packed columns and/or ejectors with an alkaline solution (e.g. sodium hydroxide solution) as scrubbing liquid;
(ii) hydrogen peroxide dosing equipment or a separate wet scrubber with hydrogen peroxide if necessary to reduce chlorine dioxide concentrations;
(iii) size suitable for the worst case scenario (derived from a risk assessment), in terms of produced chlorine quantity and flowrate (absorption of the full cell room production for a sufficient duration until the plant is shut down);
(iv) size of the scrubbing liquid supply and storage capacity suitable to ensure an excess at all times;
(v) in the case of packed columns, their size should be suitable to prevent flooding at all times;
(vi) prevention of ingress of liquid chlorine into the absorption unit;
(vii) prevention of backflow of scrubbing liquid into the chlorine system;
(viii) prevention of solids precipitation in the absorption unit;
(ix) use of heat exchangers to limit the temperature in the absorption unit below 55 °C at all times;
(x) supply of dilution air after chlorine absorption to prevent the formation of explosive gas mixtures;
(xi) use of construction materials which withstand the extremely corrosive conditions at all times;
(xii) use of backup equipment, such as an additional scrubber in series with the one in operation, an emergency tank with scrubbing liquid feeding the scrubber by gravity, stand-by and spare fans, stand-by and spare pumps;
(xiii) provision of an independent backup system for critical electrical equipment;
(xiv) provision of an automatic switch to the backup system in case of emergencies, including periodic tests on this system and the switch;
(xv) provision of a monitoring and alarm system for the following parameters:
(a) chlorine in the outlet of the absorption unit and the surrounding area;
(b) temperature of the scrubbing liquids;
(c) reduction potential and alkalinity of the scrubbing liquids;
(d) suction pressure;
(e) flowrate of scrubbing liquids.
The BAT-associated emission level for chlorine and chlorine dioxide, measured together and expressed as Cl2, is 0,2 – 1,0 mg/m3, as an average value of at least three consecutive hourly measurements performed at least once every year at the outlet of the chlorine absorption unit. The associated monitoring is in BAT 7.
BAT 9: The use of carbon tetrachloride for the elimination of nitrogen trichloride or the recovery of chlorine from tail gas is not BAT.
BAT 10: The use of refrigerants with a high global warming potential, and in any case higher than 150 (e.g. many hydrofluorocarbons (HFCs)), in new chlorine liquefaction units cannot be considered BAT.

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Source: https://www.legislation.gov.uk/eudn/2013/732/annex/division/4/division/6 (the official version)
Page: https://openlegislation.uk/eu-decision-2013-732/annex/division-4/division-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.