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(BAT) Reference Document for the Production of Chlor-alkali ...

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Chapter 4<br />

demineralised water are equal to EUR 3.8 million. This results in a payback time on investment<br />

costs <strong>of</strong> two and a half to three years [ 128, SABIC 2008 ].<br />

Driving <strong>for</strong>ce <strong>for</strong> implementation<br />

The driving <strong>for</strong>ce <strong>for</strong> implementation <strong>of</strong> this technique is a reduction <strong>of</strong> operating costs due to<br />

reduced consumption <strong>of</strong> salt and water.<br />

Example plants<br />

AkzoNobel in Bitterfeld (Germany), chlorine capacity 87.8 kt/yr;<br />

Arkema in Saint Auban (France); chlorine capacity 20 kt/yr;<br />

Dow in Stade (Germany), chlorine capacity 1585 kt/yr;<br />

SABIC in Bergen op Zoom (Ne<strong>the</strong>rlands), chlorine capacity 89 kt/yr;<br />

Zachem in Bydgoszcz (Poland), chlorine capacity 72 kt/yr.<br />

<strong>Reference</strong> literature<br />

[ 3, Euro <strong>Chlor</strong> 2011 ], [ 33, Euro <strong>Chlor</strong> 2011 ], [ 57, EIPPCB 2011 ], [ 128, SABIC 2008 ],<br />

[ 129, Euro <strong>Chlor</strong> 2007 ], [ 220, Polish Ministry 2011 ]<br />

4.3.2.2 Water<br />

4.3.2.2.1 Overview<br />

Water which is consumed in <strong>the</strong> production <strong>of</strong> chlor-<strong>alkali</strong> leaves <strong>the</strong> process ei<strong>the</strong>r via <strong>the</strong><br />

products (hydrogen and caustic solution) or as waste water (see Section 3.3.2).<br />

With regards to <strong>the</strong> generation <strong>of</strong> waste water, various techniques can be used to reduce water<br />

consumption which are described in <strong>the</strong> following sections. A general overview can be found in<br />

<strong>the</strong> CWW BREF [ 124, COM 2011 ] and in [ 132, Germany 2000 ].<br />

4.3.2.2.2 Brine recirculation<br />

Description<br />

This technique consists in resaturating <strong>the</strong> depleted brine from <strong>the</strong> electrolysis cells with solid<br />

salt or by evaporation. The saturated brine is fed back to <strong>the</strong> cells.<br />

Technical description<br />

A detailed description <strong>of</strong> <strong>the</strong> brine recirculation system is given in Section 2.5.<br />

Achieved environmental benefits<br />

The achieved environmental benefits <strong>of</strong> this technique include <strong>the</strong> following:<br />

reduction <strong>of</strong> water consumption;<br />

reduction <strong>of</strong> salt consumption;<br />

reduction <strong>of</strong> chloride emissions.<br />

WORKING DRAFT IN PROGRESS<br />

Environmental per<strong>for</strong>mance and operational data<br />

Almost all membrane cell chlor-<strong>alkali</strong> plants in EU-27 and EFTA countries use a brine<br />

recirculation system. The average volume <strong>of</strong> waste water discharged is approximately 2 tonnes<br />

per tonne <strong>of</strong> chlorine produced [ 73, Debelle 2011 ]. For comparison, 9 – 11 tonnes <strong>of</strong> water per<br />

tonne <strong>of</strong> chlorine produced are discharged as waste water when using a once-through brine<br />

process (see Section 4.3.2.3.7).<br />

188 December 2011 TB/EIPPCB/CAK_Draft_1

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