PROCESS ECONOMICS PROGRAM SRI INTERNATIONAL Menlo Park, California 94025 Abstract Proceee Economic Program Report No. 61 D CHLORINE (June 1992) Chloralkali producers around the world - in the major industrialized countries in particular - are pondering the balance between sagging demand for chlorine and strong demand for caustic soda. The former is caused by increasing environmental pressure in the following major sectors: Dioxin generated during pulp bleaching with chlorine has forced the pulp and paper industry to switch from chemical bleaching to chemi-thermal mechanical bleaching, replacing chlorine with hydrogen peroxide. Serious depletion of ozone layers has caused the major industrialized countries to totally phase out CFC production by 1995-l 996,4 to 5 years ahead of the deadline set by the 1990 internationally approved Montreal Protocol. Laws in Western Europe have been proposed to restrict the use of PVC for food and nonfood packaging. This report, a supplement to PEP Report 61 C issued in December 1962, presents a comprehensive review of technology and economics for the production of primary chlorine by electrolysis of brine in the membrane cell, diaphragm cell, or mercury cell processes, and production of secondary chlorine by catalytic oxidation as well as electrolysis of HCI. Also presented are preliminary economicsfor process conversion and retrofit from either mercury cells or diaphragm cells to membrane cells. PEP 92 YRC
Report No. 61 D CHLORINE SUPPLEMENT D by YU-REN CHIN with contributions by CHEE-HORNG CHANG MING-KUNG SHEN June 1992 A private report by the Menlo Park, California 94025
For detailed marketing data and information, the reader is referred to one of the SRI programs specializing in marketing research. The CHEMCAL ECONOMCS HANDBOOK Program cwers most major chemicals and chemical products produced in the United States and the WORLD PETROC#EM/CALS Program covers major hydrocarbons and their derivatives on a worldwide basis. In addition, the SRI D/RECTORY OF CHEMICAL PRODUCERS services provide detailed lists of chemical producers by company, product, and plant for the United States, Western Europe, Canada, and East Asia.
1 INTRODUCTION... l-l 2 SUMMARY... 2-l GENERAL ASPECTS... 2-l CHLORINE MANUFACTURING TECHNOLOGY.... 2-l Technology For Primary Chlorine.... 2-l Membrane Cell T-logy... 2-2 Diaphragm Cell Technology... 2-3 Mercury Cell Technology... 2-3 Conversion and Retroflt... 2-4 Technology For Secondary Chlorine... 2-4 ECONOMICS OF CHLORINE PRODUCTlON... 2-5 Primary Chlorine Production... 2-5 Secondary Chlorine Production... 2-6 3 INDUSTRYSTATUS... 3-l CHLORINESUPPLY... 3-1 Chloralkali Production in the United States... 3-2 Chloralkall Production in Western Europe... 3-3 Chloralkall Production in Japan... 3-3 Chloralkali Production in Canada... 3-3 Chloralkali Production In Other Regions... 3-3 CHLORINE DEMAND... 3-32 Chloralkali Demand in the United States... 3-32 Chloralkali Demand in Western Europe... 3-32 Chloralkall Demand in Japan... 3-33 Chloralkali Demand in Canada... 3-33 Chloralkali Demand in Other Regions... 3-34 4 REVIEW OF TECHNOLOGY FOR ELECTROLYSIS OF SALT... 4-l CHEMISTRY... 4-l QUALITYOFBRINE... 4-3 - iii -
CONTENTS (Continued) 4 REVIEW OF TECHNOLOGY FOR ELECTROLYSIS OF SALT (Concluded) ELECTRODES... 4-4 Anodes... 4-4 Cathodes... 4-5 DIAPHRAGM PROCESSES... 4-8 Diaphragms... 4-7 Diaphragm Electrolyzer... 4-7 MEMBRANE PROCESSES... 4-8 Composition of Membrane... 4-8 Mamfaclure of Membranes... 4-9 Properties and Performance of Membranes... 4-10 CommercialMembranes... 4-11 Struclure of Membrane Electrolyzers... 4-12 PowerConsumption... 4-17 Commercial Membrane Electrolyzers... 4-28 OPERARON OF MEMBRANE ELECTROLYZERS... 4-25 MERCURY CELL PROCESSES... 4-28 Commercial Mercury Electrolyzers... 4-28 CAUSTIC SODA... 4-27 CHLORINE... 4-28 SMALL ELECTROLYTIC CELLS... 4-28 OTHER ELECTROLYTIC CELLS... 4-28 6 ECONOMICS OF ELECTROLYTlC PROCESSES FOR CHLORINE... 5-l MEMBRANE CELL PROCESS... 5-l Process Description... 5-2 BrInePurification... 5-2 Electrolysis... 5-4 Caustic Soda Concentration... 5-4 ChlorIneRecovery... 5-5 Hydrogen Chloride Formation... 5-5 Hydrogen Recwery... 5-5 -iv-
CONTENTS (Continued) 5 ECONOMICS OF ELECTROL~C PROCESSES FOR CHLORINE (Concluded) Process Discussion... 5-13 CostEstimates... 5-14 DIAPHRAGM CELL PROCESS... 5-24 Cost Estimates... 5-24 MERCURY CELL PROCESS... 5-33 CostEstimates..... 5-33 ECONOMICCOMPARISON... 5-42 6 CONVERSION OR RETROFIT OF ELECTROLYTICELLS.................... 6-l REViRN OF PATENTS... 6-2 EFFECTS OF CONVERSION OR REiROFiT ON PLANT OPERATIONS... 6-3 Brine Purification... 6-4 Rectifier/Transformer System... 6-4 CellRoom... 6-4 CirculationSystem... 6-5 Dechlorination of Anolyte... 6-5 Caustic Concentration... 6-5 Chlorine and Hydrogen Recovery... 6-6 Off-siteStorage... 6-6 ECONOMICS OF PROCESS CONVERSION, RETROFTT, OR COMBINATIONS... Case 1: Conversion of Diaphragm Cells to Membrane Cells... ProcessConversion... EconomicsofConversion... Case 2: Retrofitting a Diaphragm Cell Process to a Membrane Cell Process... ProcessRetrofit... Economicsof Retrofit... Case 3: Conversion of Mercury Cells to Membrane Cells... ProcessConversion... Economicsof Conversion... Case 4: Combination of Diaphragm Cells with Membrane Cells... Diaphragm/Membrane Combination System... Economics of Diaphragm/Membrane Combination System... 6-6 6-6 6-7 6-6 6-13 6-13 6-13 6-20 6-20 6-20 6-26 6-26 6-27 -V-
CONTENTS (Concluded) 6 CONVERSION OR RETROFIT OF ELECTROLYnC CELL (Concluded) Case 5: Combination of Mercury Cdls with Membrane Cells... 6-32 Mercury/Membrane Combination System... 6-32 Economics of Mercury/Membrane Combination System... 6-33 7 CHLORINE RECOVERY FROM HYDROGEN CHmRIDE,..................... 7-l OXYCHLORINATION...................................................... 7-l HCI ELECTROLYSIS...................................................... 7-l CATALynC OXlDATtON OF HCI............................................ 7-4 8 ECONOMICS OF PROCESSES FOR RECOVERY OF CHU)RINE FROM HCI... 6-l CHUJRINE FROM HCI BY OXlDATtON WlTH A CHROMIUM OXIDE CATALYST... 6-l Process Description... 6-l Hydrogen Chloride Purification and Oxidation... 6-l Chlorine Purification... 6-4 Process Discussion... 6-10 Cost Estimates... 6-11 CHWRINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS... 6-26 Process Description... 6-26 HCI Purification and Absorption... 8-26 Electrolysis of HCI... 8-26 Chlorine Purification and Liquefaction... 8-29 Process Discussion... 8-35 Cost Estimates... 8-35 APPENDIX A: PATENT SUMMARY TABLES... APPENDIX B: DESIGN AND COST BASES... APPENDIX C: CITED REFERENCES... APPENDIX D: PATENT REFERENCES BY COMPANY... APPENDIX E: PROCESS FLOW DIAGRAMS.....*.*...a... A-l B-l C-l D-l E-l
4.1 ELECTRIC CONDUCTIVITY OF MEMBRANES......................... 4-l 3 4.2 ELECTROLYTIC PERFORMANCE OF FLEMION 753.................... 4-l 5 4.3 CONFIGURATION OF ELECTROLYZERS............................. 4-18 5.1 CHLORINE BY MEMBRANE CELL PROCESS PROCESS FLOW DIAGRAM....................................... E-3 5.2 CHLORINE BY MEMBRANE CELL PROCESS EFFECT OF OPERATING LEVEL AND PLANT CAPACITY ON PRODUCT VALUE OF ECU.................................... 5-23 6.1 COMBINATION OF DIAPHRAGM CELL PROCESS MEMBRANCE CELL PROCESS................................................ 6-29 6.2 COMBINATION OF MERCURY CELL PROCESS WITH MEMBRANE CELL PROCESS..................................... 6-42 7.1 SKETCH DIAGRAM OF HCI ELECTROLYRCCELL............................................ 7-3 8.1 CHLORINE FROM CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST PROCESS FLOW DIAGRAM....................................... E-Q 6.2 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST EFFECT OF OPERATING LEVEL AND PLANT CAPACITY ON PRODUCT VALUE............................................ 8-l 8 8.3 CHLORINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS PROCESS FLOW DIAGRAM..................................,.... E-11 6.4 CHLORINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS BLOCK DIAGRAM.....................,.....................,... 8-26 8.5 CHLORINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS EFFECT OF OPERATING LEVEL AND PLANT CAPACITY ON PRODUCT VALUE............................................ 8-41 - vii -
2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.6 3.9 3.10 3.11 PERCENTAGE DlSTRlBUTiON OF CHLORINE ELECTROLYTIC PROCESSES (AS OF DECEMBER 1991),... WORLDWIDE DISTRIBUTION OF LICENSED MEMBRANE CELL TECHNOLOGY........................ PRIMARY CHLORINE FROM SODIUM CHLORIDE BY ELECTROLYSIS PROCESSES SUMMARY OF ECONOMICS...................................... FIVE CASES OF PROCESS CONVERSION, RETROFTT, OR COMBINATIONS SUMMARY OF PREUMINARY ECONOMIC EVALUATION............... MEMBRANE AND MERCURY CELL COMBINATION COMPARED WITH GRASS-ROOTS MEMBRANE PROCESSES SUMMARYOFECONOMICS...................................... SECONDARY CHLORINE FROM HYDROGEN CHLORIDE BY CATALYTiC OXIDATION AND ELECTROLYSIS PROCESSES SUMMARY OF ECONOMICS........................... m,......... WORLD CAPACI-IY OF ELECTROLYTIC CHLORINE PRODUCTION....... U.S. PRODUCERS OF CHLORINE AND CAUSTIC SODA................ WESTERN EUROPEAN PRODUCERS OF CHLORINE AND CAUSTlCSODA... JAPANESE PRODUCERS OF CHLORINE AND CAUSTIC SODA.......... CANADIAN PRODUCERS OF CHLORINE AND CAUSTIC SODA.......... EASTERN EUROPEAN PRODUCERS OF CHLORINE AND CAUSTlCSODA... PRODUCERS OF CHLORINE AND CAUSTIC SODA IN OTHER COUNTRIES........................................... U.S. CONSUMPTION OF CHLORINE AND CAUSTIC SODA............. WESTERN EUROPEAN CONSUMPTION OF CHLORINE AND CAUSTIC SODA................................................. JAPANESE CONSUMPTION OF CHLORINE AND CAUSllC SODA........ CANADIAN CONSUMPTION OF CHLORINE AND CAUSTIC SODA....... 2-2 2-3 2-8 2-Q 2-10 2-11 3-4 3-5 3-8 3-13 3-16 3-17 3-20 3-35 3-36 3-37 3-38
TABLES (Continued) 4.1 BRINE PURIFICATION PATENTSUMMARY... A-3 4.2 ALLOWABLE IMPURllY LIMITS IN BRINE FOR MEMBRANE CELL ELECTROLYSIS................................. 4-5 4.3 ANODES FOR ELECTROLYSIS OF SALT PATENT SUMMARY.............................................. A-7 4.4 CATHODES FOR ELECTROLYSIS OF SALT PATENTSUMMARY... A-10 4.5 OXYGEN CATHODES FOR DIAPHRAGM CELL AND MEMBRANE CELL PATENT SUMMARY.......,...................................... A-16 4.6 DIAPHRAGM FROM ASBESTOS AND POLYMER PATENTSUMMARY... A-21 4.7 DIAPHRAGM FROM POLYMERS PATENTSUMMARY... A-24 4.8 STRUCTURE OF DIAPHRAGM CELLS PATENTSUMMARY... A-27 4.9 IMPROVED PERFORMANCE OF DIAPHRAGM CELLS PATEMSUMMARY... A-31 4.10 MEMBRANES FOR ELECTROLMlC CELLS PATENTSUMMARY... A-33 4.11 FEATURES OF COMMERCIAL MEMBRANES......................... 4-14 4.12 STRUCTURE OF MEMBRANE CELLS PATENTSUMMARY... A-44 4.13 SOUD POLYMERIC ELECTROLYTE CELLS PATENT SUMMARY.............................................. A-66 4.14 ELECTROLYZER IN COMBINATION WITH FUEL CELL PATENTSUMMARY n... A-69 4.15 CONFIGURATION OF COMMERCIAL MEMBRANE ELECTROLYZERS..... 4-22 4.16 MANUFACTURERS OF MEMBRANE ELECTROLYZERS................. 4-23 4.17 PERFORMANCE OF COMMERCIAL MEMBRANE ELECTROLYZERS...... 4-24 4.18 PERFORMANCE OF MEMBRANE CELLS PATENTSUMMARY... A-70 -X-
TABLES (Continued) 4.19 REPAIR AND REGENERATION OF CATION EXCHANGE MEMBRANES PATENT SUMMARY.............................................. 4.26 MERCURY CELLS PATENTSUMMARY... 4.21 CAUSTIC SODA BY ELECTROLYSIS OF BRINE PATENTSUMMARY... 4.22 CHLORINE BY ELECTROLYSIS OF BRINE PATENTSUMMARY... 4.23 SMALL ELECTROLYnC CELLS PATENTSUMMARY.............................................. 4.24 MULTICOMPARTMENT CELLS AND CELLS IN SERIES PATENTSUMMARY... 5.1 CHLORINE BY MEMBRANE CELL PROCESS DESIGN BASES AND ASSUMPTIONS............................... 5.2 CHLORINE BY MEMBRANE PROCESS STREAM FLOWS............................................... 5.3 CHLORINE BY MEMBRANE CEU PROCESS MAJOR EQUIPMENT............................................. 5.4 CHLORINE BY MEMBRANE CELL PROCESS UTILITIES SUMMARY............................................ 5.5 CHLORINE BY MEMBRANE CELL PROCESS TOTAL CAPITAL INVESTMENT..................................... 5.6 CHLORINE BY MEMBRANE CELL PROCESS CAPITAL INVESTMENT BY SECTION................................ 5.7 CHLORINE BY MEMBRANE CELL PROCESS PRODUCTION COSTS........................................... 5.8 CHLORINE BY MEMBRANE CELL PROCESS (ECU BASIS) PRODUCTION COSTS,.......................................... 5.9 CHLORINE BY DIAPHRAGM CELL PROCESS DESIGN BASES AND ASSUMPTIONS............................... 5.10 CHLORINE BY DIAPHRAGM CELL PROCESS TOTAL CAPITAL INVESTMENT,...-... A-74 A-75 A-77 A-79 A-80 A-82 5-3 5-6 5-Q 5-12 5-16 5-17 5-19 5-21 5-25 5-26 -xi -
TABLES (Contlnued) 5.11 CHLORINE BY DIAPHRAGM CELL PROCESS CAPITAL INVESTMENT BY SECTION................................ 5-27 5.12 CHLORINE BY DIAPHRAGM CELL PROCESS PRODUCTION COSTS........................................... 5-29 5.13 CHLORINE BY DIAPHRAGM CELL PROCESS (ECU BASIS) PRODUCTiON COSTS........................................... 5-31 5.14 CHLORINE BY MERCURY CELL PROCESS DESIGN BASES AND ASSUMPTIONS............................... 5-34 5.15 CHLOFilNE BY MERCURY CELL PROCESS TOTAL CAPITAL INVESTMENT............................,........ 5-35 5.16 CHLORINE BY MERCURY CELL PROCESS CAPITAL INVESTMENT BY SECTION................................ 5-36 5.17 CHLORINE BY MERCURY CEU PROCESS PRODUCTtON COSTS........................................... 5-38 5.18 CHLORINE BY MERCURY CELL PROCESS (ECU BASIS) PRODUCTION COSTS........................................... 5-40 5.19 THE ELECTROLYSIS PROCESSES ECONOMICS COMPARED........................................ 543 6.1 REi-ROFIlliNG OR CONVERSION OF DIAPHRAGM OF MERCURM PROCESS TO MEMBRANE PROCESS PATENTSUMMARY... A-84 6.2 COMBlNATlON OF MEMBRANE CELL WITH DIAPHRAGM OR MERCURY CELL PATENT SUMMARY.............................................. A-87 6.3 CASE 1 CONVERSION OF DIAPHRAGM CELL PROCESS TO MEMBRANE CELL PROCESS DESIGN BASES AND ASSUMPTIONS............................... 6-7 8.4 CASE 1 CONVERSION OF DIAPHRAGM CELL PROCESS TO MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT.............................. 6-11 -xii -
TABLES (Co-ed) 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 CASE 1 CONVERSION OF DIAPHRAGM CELL PROCESS TO MEMBRANE CELL PROCESS SAVINGS IN PRODUCTION COSTS................................. 6-12 CASE 2 RETROFIT OF DIAPHRAGM CELL PROCESS WITH MEMBRANE CELL PROCESS DESIGN BASES AND ASSUMPTIONS............................... 6-16 CASE 2 (A-TYPE MBC) RETROFIT OF DIAPHRAGM CELL PROCESS TO MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT..................... 6-17 CASE 2 (B-TYPE MBC) RElROFlT OF DIAPHRAGM CEU PROCESS TO MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT..................... 6-16 CASE 2 RETROFIT OF DIAPHRAGM CELL PROCESS TO MEMBRANE CELL PROCESS SAVINGS IN PRODUCTION COSTS................................. 6-19 CASE 3 CONVERSION OF MERCURY CELL PROCESS TO MEMBRANE CEU PROCESS DESIGN BASES AND ASSUMPTIONS............................... 6-23 CASE 3 CONVERSION OF MERCURY CELL PROCESS TO MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT.............................. 6-24 CASE 3 CONVERSION OF MERCURY CELL PROCESS TO MEMBRANE CELL PROCESS SAViNGS IN PRODUCTiON COSTS................................. 6-25 CASE 4 COMBiNATiON OF DIAPHRAGM CELL PROCESS WITH MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT.............................. 6-30 - xiii -
TABLES (Contlnued) 6.14 6.15 6.16. 8.17 6.18 8.19 6.20 7.1 7.2 8.1 8.2 CASE 4 COMBINATION OF DIAPHRAGM CELL PROCESS WITH MEMBRANE CELL PROCESS SAVINGS IN PRODUCTION COSTS....,......................... 6-31 CASES 5-l AND 5-2 COMBINATION OF MERCURY CELL PROCESS WITH MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT.............................. 6-36 CASE 5-3 COMBINATION OF MERCURY CELL PROCESS WITH MEMBRANE CELL PROCESS INCREMENTAL CAPITAL INVESTMENT.............................. 6-37 CASE 5-l AND 5-2 COMBINATION OF MERCURY CELL PROCESS WITH MEMBRANE CELL PROCESS SAVINGS IN PRODUCTION COSTS................................. 6-36 CASE 5-3 COMBINATION OF MERCURY CELL PROCESS WITH MEMBRANE CELL PROCESS PRODUCTION COSTS........................................... 6-39 MEMBRANE AND MERCURY CELL COMBINATION COMPARED WITH GRASS-ROOTS MEMBRANE PROCESS....................... 6-40 CONVERSION, RETROFIT OR COMBINATION OF DIAPHRAGM OR MERCURY CELL PROCESSES WITH MEMBRANE CELL PROCESS SUMMARY OF PRELIMINARY ECONOMICS.......................... 6-41 HYDROGEN CHLORIDE ELECTROLYSIS PATENTSUMMARY... A-68 CATALYTIC OXIDATION OF HYDROGEN CHLORIDE PATENTSUMMARY... A-90 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST DESIGN BASES AND ASSUMPTIONS............................... 6-2 CHLORINE FROM HYDROGEN CHLORIDE BY OXlDAllON WITH A CHROMIUM OXIDE CATALYST STREAM FLOWS................................................ 8-5 - xiv -
TABLES (Continued) 8.3 8.4 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST MAJOR EQUIPMENT............................................ CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM BASED CATALYST UTILITIES SUMMARY........................................... 8-7 8-Q 8.5 8.6 8.7 8.8 6.9 6.10 8.11 6.12 8.13 8.14 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST TOTAL CAPITAL INVESTMENT..................................... 8-14 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST CAPITAL INVESTMENT BY SECTION................................ 6-15 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST PRODUCTION COSTS...................................,....... 6-l 6 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH NITROGEN OXIDE AS CATALYST TOTAL CAPITAL INVESTMENT..................................... 8-19 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WiTH NITROGEN OXIDE AS CATALYST CAPiTAL INVESTMENT BY SECTION................................ 6-20 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH NITROGEN OXIDE AS CATALYST PRODUCTION COSTS........................................... 6-21 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH NITROGEN OXIDE AS CATALYST (EQUAL AMOUNT OF HCL FEEDSTOCK) PRODUCTIONCOSTS........................................... 6-23 CHLORINE FROM HYDROGEN CHLORIDE BY OXIDATION WITH A CHROMIUM OXIDE CATALYST (WITH RECOVERY AND RECYCLE OF UNCOVERTED HCI) PRODUCTION COSTS........................................... 8-24 CHLORINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS DESIGN BASES AND ASSUMPTIONS............,.................. 8-27 CHLORINE FROM HYDROCHLORIC ACID BY ELECTROLYSIS STREAM FLOWS............................................... 8-30 -xv-
TABLES (Concluded) 8.15 CHLORINE FROM HYDROGEN CHLORIDE BY ELECTROLYSIS MAJOR EQUIPMENT...................,........................ 8-32 8.16 CHLORINE FROM HYDROGEN CHLORIDE SY ELECTROLYSIS UTlLlTlESUMMARY............................................ 8-34 8.17 CHLORINE FROM HYDROGEN CHLORIDE BY ELECTROLYSIS TOTAL CAPKAL INVESTMENT..................................... 8-37 8.18 CHLORINE FROM HYDROGEN CHLORIDE BY ELECTROLYSIS CAPITAL INVESTMENT BY SECTION................................ 6-38 8.19 CHLORINE FROM HYDROGEN CHLORIDE BY ELECTROLYSIS PRODUCTION COSTS........................................... 8-39 8.20 ECONOMICS OF THE PROCESSES COMPARED..................... 8-42 -xvi-