| 1 |
Front Matter |
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Abstract
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| 2 |
Introduction |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
The chlor-alkali industry is one of the largest electrochemical operations in the world, the main products being chlorine and sodium hydroxide generated simultaneously by the electrolysis of sodium chloride solutions. The chlor-alkali industry serves the commodity chemical business, chlorine and sodium hydroxide (also called caustic soda) being indispensable intermediates in the chemical industry [.–.].
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| 3 |
History of the Chlor-Alkali Industry |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
During the last half of the 19th century, chlorine, used almost exclusively in the textile and paper industry, was made [.] by reacting manganese dioxide with hydrochloric acid
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| 4 |
Overview of the Chlor-Alkali Industry |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
The world production capacity of chlorine reached 53 million tons in 2002 from approximately 22 million tons in 1970 [.–.] and is expected to increase to 65 million tons by the year 2015 [.]. In this chapter, the major manufacturing processes and the factors affecting the growth pattern of the chlor-alkali industry are presented.
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| 5 |
Chemistry and Electrochemistry of the Chlor-Alkali Process |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Thermodynamics is a powerful tool for the study of chemical reactions and is intimately related to the atomic and molecular description of the species participating in these reactions. The transformation of energy involved in the reactions depends on the thermodynamic conditions of the reaction, and can be expressed in terms of various thermodynamic functions. One such function is the Gibbs free energy [.–.], expressed by Eq.(l):
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| 6 |
Chlor-Alkali Technologies |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
About 97 % of the chlorine and nearly 100% of the caustic soda in the world are produced electrolytically from sodium chloride, while the rest of the chlorine is manufactured by the electrolysis of KC1, HC1, chlorides of Ti and Mg, and by the chemical oxidation of chlorides [.]. The electrolytic technologies currently used are mercury, diaphragm, and ion-exchange membrane cells. Figures 5.1 and 3.10 show the distribution of these cell technologies in the world and on a regional basis [.]. Mercury cells had a world share of 45% in 1984 and declined to 18% in 2001 because of the health and environmental concerns associated with mercury. However, it is still the leading technology in Europe.
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| 7 |
Process Overview |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
This chapter presents a general overview of the processing steps in a typical chlor-alkali plant. As shown in Fig. 6.1, we can divide the process into three major steps. These are the preparation of purified brine, electrolysis, and processing of the crude products of electrolysis. The figure also subdivides brine preparation into its main elements. Later sections present flowsheets in block form for each of the process steps. A discussion of the differences among the various types of electrolyzer technology accompanies each flow diagram. Separate flowsheets for the complete processes for the three electrolyzer technologies are also available in the literature [., .].
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| 8 |
Brine Preparation and Treatment |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
This chapter considers the preparation of brine from solid salt and the design and operation of each of the major units in a brine purification system. The discussion begins with the sources of electrolysis salts (both sodium and potassium chlorides; both natural and refined) and the methods of handling and storing them and then dissolving them to prepare brine. There is also a brief discussion of the storage and handling of brine. The rest of the chapter is then devoted to the treatment of brine to reach the purity demanded by the various types of cell. The sequence of the discussion follows the flow diagrams of Figs. 6.1 and 6.2.
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| 9 |
Cell-Room Design |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
In their design and construction, electrochemical plants differ from ordinary chemical plants in several ways:
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| 10 |
Product Handling |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
The first three sections of this chapter discuss the processing and handUng of the products of electrolysis. Section 9.1, related to chlorine, comprises most of the chapter. Sections 9.2 and 9.3 then cover hydrogen and caustic soda or potash. Section 9.4 discusses applications of several byproducts that are sometimes found useful.
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| 11 |
Chemical Engineering Principles |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
The purpose of this chapter is to gather in one place some of the basic considerations that apply to the engineering techniques and unit operations that are important in the chloralkali process. Thus, the chapter begins with a discussion of material and energy balances (Section 10.2). These are basic to all of chemical engineering and are used implicitly throughout this book. Here, we present some of the fundamentals. Section 10.3 then covers current distribution. This is uniquely important in electrochemical processing. The presentation discusses methods of predicting and determining the distribution of current in electrochemical reactors of different kinds.
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| 12 |
Instrumentation and Control Systems |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Chapters 7 through 9 have already covered the processes involved in a chlor-alkali plant, along with some of the essentials of their control. This chapter goes into the details of control systems and hardware. The discussion, where differences exist, focuses primarily on the membrane-cell process. The chlorine and hydrogen processes are essentially the same regardless of the type of cell used. Control of absolute and differential pressures is especially important in the gas systems, and so the discussion is divided primarily according to operating pressure level. Membrane cells require extremely pure brine, and some of the operations used are not necessary with the other types of cell. Otherwise, mercury-cell brine systems are for the most part very similar to those in membranecell plants, but they require their own special features and precautions to prevent the escape of mercury into the environment. Diaphragm cells require approximately the same treatment of new brine, but, unlike the situation with the other cells, there is no direct recycle of the anolyte. Therefore, the discussion of brine systems follows the membranecell process, which is the most comprehensive of the three.
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| 13 |
Utilities |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
This chapter considers the major utility systems in a chlor-alkali plant. These include electricity (Section 12.2), steam and condensate (Section 12.3), the various water systems (Section 12.4), air and nitrogen (Section 12.5), and, for convenient grouping, vacuum (Section 12.6). Finding the best basis for a discussion of utilities in a work such as this is difficult. A comprehensive description is impossible in a reasonable amount of space, and in any case it is undesirable where the emphasis is to be on chlor-alkali technology itself. Our approach is to discuss the individual utilities from the standpoint of a chlor-alkali plant operator while avoiding the complexities of such things as steam boilers.
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| 14 |
Plant Commissioning and Operation |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Commissioning is the activity whereby the installed hardware of a new plant is transformed into an operational facility. Most works on industrial chemical technology ignore the subject/However, it is an extremely important topic, and the successful startup and subsequent operation of a new plant are critically dependent on the approach taken toward its commissioning.
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| 15 |
Corrosion |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Corrosion is a multibillion dollar worldwide problem. In the United States, corrosion is estimated [.] to occur at a rate of 14,000 kg min., costing about $200 billion per year. Incidents from corrosion may force shutdowns of chemical plants, the associated penalties in serious situations being financial loss, loss of human life, and damage to the environment. It is for these reasons that all chemical plants emphasize safety and implement safe operations by training plant personnel. Safety management extends into ensuring proper selection of materials of construction, quality control during manufacturing, fabrication, and construction, and routine maintenance during normal plant operations.
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| 16 |
Alternative Processes |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Chlorine is produced not only by the electrolysis of sodium chloride solutions but also from HC1, KC1, and other metal chlorides, by both chemical and electrochemical methods. The amount of chlorine from alternative processes is about 5.9% of the total world production. In the United States, it was about 4.0% of the total in 2002 [.]. Most of this chlorine was from the electrolysis of KC1 in mercury or membrane cells (Table 15.1) and from HC1. Only small amounts are produced by the electrolysis of other metal chlorides.
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| 17 |
Environmental Safety and Industrial Hygiene |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Safety considerations are inseparable from the principles of good design and operation and so have been a constant theme in our discussion of the chlor-alkali process. The preceding chapters deal with the practical details of direct protection of personnel in the workplace. They refer frequently to the programs and publications of various organizations with special interest in industrial safety. Other publications [., .] also discuss operating safety and provide guidance in design and operation. In this chapter, we consider safety more generally and also provide more quantitative information on hazard levels. To put those hazards in perspective and show the degree of success the industry has had in coping with them, consider the following [.]:
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| 18 |
Future Developments |
Thomas F. O’Brien,Tilak V. Bommaraju,Fumio Hine |
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Abstract
Chapter 2 recounts some of the history of chlor-alkali technology and production. While very important industrially, the process is an old one and, as one of the few examples of large-scale electrochemical production, somewhat outside the mainstream of chemical research and development. The industry is part of the commodity chemical business and has often faced difficult economic problems. All this seems a recipe for technological stagnation. However, the past few decades have seen two major developments that have had profound effects on the technology and economics of production. These are the introduction of metal anodes and the partial substitution of membrane technology for the older diaphragm and mercury technologies. The first of these was made possible by the development of durable, low-voltage coatings that could be applied to titanium. Metal anodes offered many advantages over graphite. Furthermore, direct replacement of graphite by metal anodes of essentially the same dimensions was also rather a simple matter. The changeout therefore was rapid. Membrane technology, on the other hand, required extensive changes in the process. Except for the “membrane-bag” cells, which we
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| 19 |
Back Matter |
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Abstract
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发表于 2025-3-21 18:34:41
