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

Chapter 4
At the INEOS ChlorVinyls plant in Runcorn (United Kingdom) and the AkzoNobel plant in
Delfzijl (Netherlands), the diaphragm cell units were shut down while expanding an existing
membrane cell unit [ 31, Euro Chlor 2010 ].
Converting to asbestos-free diaphragms
In some cases the Tephram diaphragms can directly replace the old diaphragms and the
Polyramix diaphragms can replace the old diaphragms if the cathodes are also replaced. How
much change other designs of asbestos-free diaphragms require is not known to the author at the
time of writing.
Comparison between converting to membranes or to asbestos-free diaphragms
{The comparison was updated and moved to Economics.}
Conversion of a diaphragm plant to membrane technology can be an attractive choice because
of the high energy efficiency and the pure 33% caustic produced directly from the cells. This is
especially the case when there is a need for high purity 50% caustic, due to the reduced costs of
evaporation and the higher caustic quality of the membrane technology
A conversion to asbestos-free diaphragms requires substantially less change in the existing cell
room than a conversion to membranes, and thus a lower capital investment. A comparison of the
manufacturing costs is dependent on steam costs and the required caustic quality.
The final decision of the diaphragm cell producer between membranes and asbestos-free
diaphragms will depend on the situation at the individual site.
Achieved environmental benefits
The achieved environmental benefits of this technique include:
prevention of asbestos emissions;
prevention of generation of asbestos-containing waste;
reduction of energy consumption.
Avoids emission of asbestos and, in the case of membranes, significantly reduces the energy
use. Another advantage with membranes is the increased tolerance of power fluctuations, which
is especially attractive in regions with fluctuating energy prices.
Environmental performance and operational data
A technical advantage of the conversion is that membrane cells generally exhibit an increased
tolerance to power fluctuations which is especially attractive in regions with fluctuating energy
prices [ 31, Euro Chlor 2010 ].
At the Anwil plant in Wuocuawek (Poland), the conversion led to a 50 % reduction of steam
consumption, a 5 % reduction of electricity consumption as well as the prevention of asbestos
emissions and asbestos waste generation. Furthermore, the plant eliminated the need to use
liquid ammonia to purify the caustic soda [ 31, Euro Chlor 2010 ].
WORKING DRAFT IN PROGRESS
Cross-media effects
Significant amounts of raw materials and energy are required for the installation of the new
equipment.
Technical considerations relevant to applicability
Generally, there are no technical restrictions to the applicability of this technique.
Economics
The conversion of a diaphragm cell plant to a membrane cell plant technology can be an
attractive choice because of the high energy efficiency and the pure 33 wt-% caustic produced
180 December 2011 TB/EIPPCB/CAK_Draft_1