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

Chapter 3
Table 3.5: Operating conditions and electricity consumption of the chlor-alkali electrolysis
cells in EU-27 and EFTA countries
Parameter Unit
Mercury cell technique ( 1 )
Min. Max. Average Median
Theoretical voltage V 3.15
Current density min. kA/m 2
2.2 ND 5.5 4.5
Current density max. kA/m 2
ND 14.5 10.2 10.7
Cell voltage min. V 3.15 ND 3.67 3.61
Cell voltage max. V ND 4.80 4.15 4.18
Electrical energy use
for electrolysis
(alternating current)
AC kWh/t
Cl2
3024 4400 3424 3401
Diaphragm cell technique ( 2 Parameter Unit
Min.
)
Max. Average Median
Theoretical voltage V 2.35
Current density min. kA/m 2
0.8 ND 1.1 1.1
Current density max. kA/m 2
ND 2.7 2.0 1.9
Cell voltage min. V 2.9 ND 2.98 2.99
Cell voltage max. V ND 3.60 3.44 3.48
Electrical energy use
for electrolysis
(alternating current)
AC kWh/t
Cl2
2621 3134 2807 2770
Membrane cell technique (monopolar and bipolar) ( 3 Parameter Unit
)
Min. Max. Average Median
Theoretical voltage V 2.35
Current density min. kA/m 2
1.0 ND 2.7 2.6
Current density max. kA/m 2
ND 6.5 5.1 5.5
Cell voltage min. V 2.35 ND 2.89 2.90
Cell voltage max. V ND 4.00 3.40 3.38
Electrical energy use
for electrolysis
(alternating current)
AC kWh/t
Cl2
2279 3000 2618 2600
( 1 ) Data from 34 mercury cell plants. Reference year 2008: 34 plants. 29 plants measured electricity consumption,
4 plants estimated it and 1 plant did not provide information if data were measured or estimated.
( 2 ) Data from 6 diaphragm cell plants. Reference year 2008: 6 plants. 5 plants measured electricity consumption
and 1 plant did not provide information if data were measured or estimated.
( 3 ) Data from 40 membrane cell plants (monopolar and bipolar). Reference year 2008: 35 plants; reference year
2009: 4 plants; reference year 2010: 1 plant. 32 plants measured electricity consumption, 6 plants estimated it
and 2 plants did not provide information if data were measured or estimated.
NB: ND = no data available.
Source: [ 58, Euro Chlor 2010 ]
3.3.4.3.2 Energy consumption of mercury cells
WORKING DRAFT IN PROGRESS
The mercury cell technique is characterised by the highest electrical energy consumption
ranging from approximately 3000 to 4400 AC kWh/t Cl2 produced, the median being
approximately 3400 AC kWh/t Cl2 produced with current densities ranging from
2.2 – 14.5 kA/m 2 (Table 3.5). The increased electrical energy consumption is due to the higher
value of U0 compared to diaphragm and membrane cells which is the result of the different
cathodic reaction. The factor K ranges from 0.085 – 0.11 V·m 2 /kA and is lower than for the two
other cell techniques as there is no physical separator between the electrodes. The median of the
minimum and maximum current densities used are 4.5 and 10.7 kA/m 2 , respectively
[ 1, Ullmann's 2006 ], [ 63, Euro Chlor 2010 ].
The voltage increases with a greater is increased with increasing distance between the anode and
the cathode, resulting in higher electrical energy consumption. On the other hand, a close
74 December 2011 TB/EIPPCB/CAK_Draft_1