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

Chapter 4
Achieved environmental benefits
The achieved environmental benefit of this technique is the prevention of carbon tetrachloride
emissions.
Avoid the use of carbon tetrachloride which is considered as harmful under the provisions of the
Montreal Protocol.
Environmental performance and operational data
Techniques not using carbon tetrachloride can be applied to new and existing plants. Hydro
Polymers in Stenungsund (Sweden) stopped using CCl4 for purification purposes some years
ago. They now use At the INEOS ChlorVinyls plant (formerly Hydro Polymers) in Stenungsund
(Sweden), the use of CCl4 for purification purposes was abandoned before 2000. Since then a
static mixer has been used to cool the gaseous chlorine as much as possible without getting any
liquefaction., and then send Subsequently, the gaseous chlorine is sent to the VCM plant where
NCl3 is decomposed at an elevated temperature. This method is a standard technique for plants
with integrated VCM production [ 75, COM 2001 ].
At the Akzo Nobel plants in Delfzijl and Rotterdam-Botlek (Netherlands), the use of carbon
tetrachloride stopped during the first decade of the 21st century in parallel to the installation of
new membrane cell units. In both plants, the intake of nitrogen compounds with the raw
materials was reduced. Furthermore, the plants were designed so as to avoid NCl3 accumulation
above critical limits. Finally, the possibility to thermally destruct NCl3 in liquid chlorine exists
but is rarely used [ 202, AkzoNobel 2010 ].
Cross-media effects
No cross-media effects occur when chlorine is directly used without liquefaction. Reducing the
intake of nitrogen compounds with the raw materials (salt, water, ancillary materials) should
also lead to minor cross-media effects except where additional purification steps are necessary.
However, some ancillary materials and energy are consumed if ammonium is removed from the
brine or if nitrogen trichloride is destroyed after its formation. Stripping of ammonia requires
additional treatment of the waste gases. The destruction of NCl3 to nitrogen and chlorine is
strongly exothermic and may require additional safety measures. When using radiation, a low
hydrogen content in chlorine has to be ensured to avoid the risk of explosions [ 36, Euro Chlor
2010 ].
If there is no market for the bleach produced from the absorption of the tail gas, some energy
and ancillary materials are required for its treatment (see Section 4.3.6.3).
Technical considerations relevant to applicability
Generally, there are no technical restrictions to the applicability of this technique.
Economics
To stop using CCl4 may involve a change of compressor type, depending on the chlorine
temperature. Depending on the plant design, some equipment may require replacement.
{Please TWG provide information.}
Driving force for implementation
The driving force for implementation of this technique is environmental legislation.
Emissions from leakage of CCl4 are avoided. Carbon tetrachloride-free chlorine liquefaction and
purification processes do not generate discarded carbon tetrachloride which has to be destroyed
according to approved destruction processes.
WORKING DRAFT IN PROGRESS
Example plants
Carbon tetrachloride-free chlorine liquefaction and purification processes are applied in
nearly all chlor-alkali plants in EU-27 and EFTA countries Europe;
AkzoNobel in Delfzijl (Netherlands), chlorine capacity 109 kt/yr;
AkzoNobel in Rotterdam-Botlek (Netherlands), chlorine capacity 633 kt/yr;
TB/EIPPCB/CAK_Draft_1 December 2011 229