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

Chapter 4
directly from the cells. This is especially the case when there is a need for high-purity 50 wt-%
caustic, due to the reduced costs of evaporation and the higher caustic quality of the membrane
technology cell technique and/or when the diaphragm cell plant is operated at current densities
> 1.5 kA/m 2 . At low current densities, the specific electricity consumption of a diaphragm cell
plant can be lower than that of a membrane cell plant (see Sections 3.3.4.3 and 4.3.2.3.2) [ 31,
Euro Chlor 2010 ].
In comparison to the use of asbestos-free diaphragms (see Section 4.2.2), the conversion to the
membrane cell technique requires a large capital investment of at least EUR 300 – 400/t annual
chlorine capacity. For example, the total investment cost for the conversion at the Anwil plant in
Wuocuawek (Poland), was approximately PLN 230 million in 2004 – 2005 (equivalent to
approximately EUR 60 million). The operating costs of the two options depend on steam and
electricity costs, labour costs and the required caustic quality [ 31, Euro Chlor 2010 ].
The final choice of a plant operator between asbestos-free diaphragms and the membrane cell
technique will therefore depend on the situation at the individual site.
Driving force for implementation
The driving forces for implementation of this technique include:
environmental as well as occupational health and safety legislation;
reduction of costs related to energy consumption;
improved quality of produced caustic.
For membranes and asbestos-free diaphragms
Environmental regulation: no emissions of asbestos
For membranes
End-use market : need for high purity caustic without salt
Economic: high energy efficiency and less need for caustic evaporation
For asbestos-free diaphragms, “the long-life diaphragm cell”
Economic: reduced operating cost and reduced amounts of solid wastes
Example plants
AkzoNobel in Bitterfeld (Germany), chlorine capacity 88 kt/yr (only membrane cells),
shutdown of diaphragm cell plant in 1997, construction of membrane cell plant in
1998 – 2000;
AkzoNobel in Delfzijl (Netherlands), chlorine capacity 109 kt/yr (only membrane
cells), conversion in 2005/2006;
Anwil in Wuocuawek (Poland), chlorine capacity 213.5 kt/yr (only membrane cells),
conversion in 2004/2005;
BASF in Ludwigshafen (Germany), chlorine capacity of membrane cell unit 215 kt/yr),
conversion in 2003;
INEOS ChlorVinyls (formerly Norsk Hydro) in Rafnes (Norway), chlorine capacity
260 kt/yr (only membrane cells), conversion in 2005;
INEOS ChlorVinyls in Runcorn (United Kingdom), chlorine capacity of membrane cell
unit 400 kt/yr.
WORKING DRAFT IN PROGRESS
Any specific examples of conversions of diaphragm plants to membranes are not known to the
author at the time of writing. However, [Dibble-White, 1988] reports involvements in the design
and implementation of conversion of diaphragm cell plants to membrane technology.
Examples of conversions of diaphragm plants to asbestos-free diaphragms, including some
economic data, are presented in the previous section, 4.3.2.
TB/EIPPCB/CAK_Draft_1 December 2011 181