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

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Chapter 4 chloride by the reaction with hydrogen in the presence of a rhodium metal catalyst on an activated carbon carrier [ 34, Solvay 2010 ], [ 49, Euro Chlor 2010 ]: ClO3 - + 3 H2 V Cl - + 3 H2O The reaction occurs in a pressurised trickle-bed reactor in the presence of a gas (hydrogen), a liquid (brine) and a solid (the catalyst). Hydrogen is used in excess and the heat generated during the exothermic reaction is removed with the brine [ 34, Solvay 2010 ]. The technique has the advantage of not requiring huge amounts of sodium hydroxide for neutralisation. Hydrogen is also readily available at chlor-alkali plants. However, the technique is more difficult to operate than acidic chlorate reduction (see Section 4.3.6.4.3). The catalyst may be destroyed by high temperatures, frequent start-up and shutdown operations, high chlorate concentrations and the absence of a reducing atmosphere in the presence of brine. The reactor start-up is therefore carried out in an oxygen-free atmosphere before adding hydrogen and the reactor shutdown involves rinsing with demineralised water before removing hydrogen [ 34, Solvay 2010 ]. The first reactor with catalytic chlorate reduction was put into operation in 2001 [ 49, Euro Chlor 2010 ]. Achieved environmental benefits The achieved environmental benefits of this technique include: reduction of chlorate emissions; reduction of salt consumption; reduction of chloride emissions due to reduced brine purge volumes. Environmental performance and operational data The efficiency of the reduction is typically in the range of 99.6 – 99.8 % with a chlorate concentration in the inlet of about 5000 mg/l and outlet concentrations of 10 – 20 mg/l. However, if the inlet concentration is lower (e.g. 800 mg/l) the outlet concentration remains at 10 – 20 mg/l, reducing the efficiency to 97.5 – 98.8 % [ 34, Solvay 2010 ]. Any bromate present in the brine is similarly reduced to bromide, the reduction efficiency being better than in the case of chlorate [ 34, Solvay 2010 ]. Cross-media effects Some raw materials and energy are consumed for the construction and operation of the reactor. The hydrogen used for catalytic chlorate readuction cannot be used for other purposes. Technical considerations relevant to applicability There are no restrictions to the applicability of this technique. Diaphragm plants do not recirculate the brine and therefore do not use catalytic chlorate reduction. Any chlorate produced during electrolysis leaves the process with the caustic liquor. WORKING DRAFT IN PROGRESS Economics {Please TWG provide information.} Driving force for implementation The driving forces for implementation of this technique include: improvement of product quality (less chlorate in caustic); reduction of costs related to equipment and maintenance; environmental legislation. 248 December 2011 TB/EIPPCB/CAK_Draft_1
Example plants Solvin in Antwerp-Lillo (Belgium), chlorine capacity 180 kt/yr; Solvin in Jemeppe (Belgium), chlorine capacity 174 kt/yr; Solvay in Rosignano (Italy), chlorine capacity 120 kt/yr; Solvay in Tavaux (France), chlorine capacity 360 kt/yr. Reference literature [ 34, Solvay 2010 ], [ 49, Euro Chlor 2010 ] 4.3.6.4.5 Use of brine purge for the production of sodium chlorate Chapter 4 Description This technique consists in recycling the brine purge of the chlor-alkali plant to the brine system of a sodium chlorate production unit. Technical description Sodium chlorate is principally used to produce chlorine dioxide, which is used as bleaching agent in the pulp and paper industry. The production of sodium chlorate is based on the electrolysis of brine under pH conditions where the chlorine from the anode combines with the sodium hydroxide from the cathode to produce sodium hypochlorite, which is converted to sodium chlorate. The involved reactions are the same as those occurring as side reactions in chlor-alkali electrolysis cells (see Section 2.1). Following electrolysis, the cell liquor is stored in tanks to finalise the transformation of hypochlorite to chlorate. Sodium chlorate is obtained from the cell liquor by concentration in a crystallisation unit and subsequent washing. The mother liquid and the washing liquids are reconcentrated using solid salt or evaporation and are recycled to the brine circuit [ 209, COM 2007 ]. By recycling the brine purge of a chlor-alkali electrolysis unit to the brine system of a sodium chlorate production unit, the chlorate produced as an unwanted substance is converted into a saleable product. Any bromate in the brine purge from the chlor-alkali unit will leave the site with the crystallised sodium chlorate or with the brine purge from the sodium chlorate unit. Achieved environmental benefits The achieved environmental benefits of this technique include: reduction of chlorate emissions; overall reduction of raw material and energy consumption; overall reduction of chloride emissions due to reduced brine purge volumes. Environmental performance and operational data At the Kemira plant in Joutseno (Finland) the brine purge from the membrane cell chlor-alkali unit is completely recycled to the sodium chlorate production unit [ 57, EIPPCB 2011 ]. Cross-media effects There are no additional cross-media effects for a site which produces both chlorine and sodium chlorate. WORKING DRAFT IN PROGRESS Technical considerations relevant to applicability The use of this technique is restricted to sites where sodium chlorate is produced. Economics {Please TWG provide information.} Driving force for implementation The driving force for implementation of this technique is a reduction of operating costs due to reduced consumption of raw materials and energy consumption. TB/EIPPCB/CAK_Draft_1 December 2011 249
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EUROPEAN COMMISSION JOINT RESEARCH
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PREFACE 1. Status of this document
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Reference Document on Best Availabl
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3.4.7 Emissions of noise ..........
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4.3.6.3.3 Chemical reduction ......
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List of Tables Table 2.1: Main char
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List of Figures Figure 1.1: Share p
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SCOPE WORKING DRAFT IN PROGRESS Sco
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1 GENERAL INFORMATION 1.1 Industria
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Chlorine production in Mt/yr 12 11
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Chapter 1 Figure 1.4 shows the annu
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Share of total capacity in % 70 70%
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1.4 Chlor-alkali products and their
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Total consumption: 9 801 kt Miscell
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1.4.5 Consumption of hydrogen Chapt
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Chapter 1 and hazardous waste incin
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2 APPLIED PROCESSES AND TECHNIQUES
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Chapter 2 WORKING DRAFT IN PROGRESS
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Chapter 2 The main characteristics
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2.2 The mercury cell technique proc
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Chapter 2 Characteristics of the ca
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2.3 The diaphragm cell technique pr
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Source: [ 2, Le Chlore 2002 ] [USEP
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2.4 The membrane cell technique pro
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Chapter 2 (carcinogenic) [ 76, Regu
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Chapter 2 The membranes used in the
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Table 2.2: Typical configurations o
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2.5 Brine supply 2.5.1 Sources, qua
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Chapter 2 centrifuges before dispos
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Source: [ 29, Asahi Glass 1998 ] (p
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Impurity Source Upper limit of brin
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Chapter 2 No such dechlorination tr
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Chapter 2 The cooling water is gene
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Chapter 2 composition of the chlori
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2.6.11 Dealing with impurities 2.6.
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Chapter 2 amount of chlorine, and t
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2.6.12.2 Chemical reactions Chapter
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2.7 Caustic processing production,
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Chapter 2 2.8 Hydrogen processing p
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3 CURRENT PRESENT EMISSION AND CONS
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Chapter 3 Table 3.1: Overview of em
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3.3 Consumption levels of all cell
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3.3.3 Ancillary materials Ancillary
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Further materials and/or further us
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Chapter 3 current) and the efficien
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Chapter 3 distance means a higher f
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3.3.4.3.6 Production of caustic pot
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Chapter 3 hydrogen at low pressure
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28 kg of hydrogen is produced {Thes
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Chapter 3 depleted brine is recircu
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Chapter 3 Table 3.10: Emissions of
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Chapter 3 When measuring chlorine i
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Chapter 3 concentrations of organic
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Chapter 3 3.4.3 Emissions and waste
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Chapter 3 {Please TWG provide infor
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Chapter 3 in process and waste wate
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Chapter 3 produced per year has bee
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Chapter 3 of chlorine capacity. The
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Table 3.23: Mercury emissions from
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Mercury emissions in g Hg/t Cl capa
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Chapter 3 Table 3.24: Mercury emiss
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Chapter 3 KCl are higher than from
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Chapter 3 When concentrated solid c
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Chapter 3 Generally, storage of con
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Chapter 3 recycled brine systems si
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Process Maintenance To solid treatm
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3.5.9.5 Graphite and activated Acti
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Chapter 3 Table 3.31: Yearly waste
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Chapter 3 The fact that the differe
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Chapter 3 3.6 Emissions Emission an
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Reported asbestos concentrations ar
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Chapter 3 3.7 Emissions Emission an
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{A list of techniques used on full
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3.8.3 PCDDs/PCDFs, PCBs, PCNs and P
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Chapter 3 The ‘dioxin’ pattern
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Chapter 4 4 TECHNIQUES TO CONSIDER
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Heading within the sections Cross-m
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4.1 Mercury cell plants 4.1.1 Overv
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Chapter 4 plants at comparable capa
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Chapter 4 Table 4.2: Data from the
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Chapter 4 environment can be expect
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4. Plant size Chapter 4 An increase
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Table 4.6: Comparison of reported c
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Chapter 4 Generally, conversion cos
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4.1.3 Decommissioning 4.1.3.1 Decom
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3. Emptying of the cells and handli
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Chapter 4 Table 4.7: Overview of co
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Table 4.8: Techniques for monitorin
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Chapter 4 Table 4.10: Decommissioni
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4.2 Diaphragm cell plants 4.2.1 Aba
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Source: [ 146, Arkema 2009 ] Figure
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Chapter 4 diaphragms [ 31, Euro Chl
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Driving force for implementation Th
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Chapter 4 4.2.3 Conversion of asbes
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Chapter 4 directly from the cells.
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4.3 All Diaphragm and membrane cell
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Chapter 4 non-standardised) will be
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Chapter 4 removal of conductive com
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Chapter 4 Cross-media effects Plant
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Environmental performance and opera
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Example plants Dow, Stade (Germany)
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Chapter 4 current density resulting
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Page 273 and 274: 4.4 Membrane cell plants 4.4.1 High
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Page 283 and 284: 5 BEST AVAILABLE TECHNIQUES Scope
Page 285 and 286: General considerations In these BAT
Page 287 and 288: 5.2 Decommissioning of mercury cell
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Page 295 and 296: 5.6 Monitoring of emissions Chapter
Page 297 and 298: [This BAT conclusion is based on in
Page 299 and 300: 5.9 Generation of waste Chapter 5 1
Page 301 and 302: 5.11 Site remediation Chapter 5 20.
Page 303 and 304: Chapter 5 inorganic chloramines, di
Page 305 and 306: 6 EMERGING TECHNIQUES 6.1 Introduct
Page 307 and 308: Chapter 6 cooperation with the Japa
Page 309 and 310: Chapter 6 In December 1998 a test w
Page 311 and 312: 6.3 Use of fuel cells in chlor-alka
Page 313 and 314: Chapter 6 hydrogen that is burnt to
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Chapter 7 7 CONCLUDING REMARKS AND
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REFERENCES References [1] Ullmann's
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References [63] Euro Chlor, Euro Ch
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References [112] Santorelli et al.,
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References [161] Germany, 'Verordnu
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[212] Florkiewicz, Long life diaphr
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References [259] Rappe et al., 'Lev
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GLOSSARY OF TERMS AND ABBREVIATIONS
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V. Units · VI. Chemical elements T
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VIII. Acronyms and definitions AC A
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EOX Extractable Organically-bound H
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Glossary Technique Ensemble of both
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ANNEX Annex {The CAK plant capaciti
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Euro Chlor No. Country code Company
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