Chlor-alkali technology overview

An overview of the three chlor-alkali technologies is presented in this chapter, and the process details are addressed in Volumes II and HI. The terminology and the overall processes discussed in this chapter should enable the reader to relate the process steps to the electrochemical and chemical engineering principles discussed in Chapters 4 and 10. 

Abstract Ion-conducting materials are used as cell separators in electrolysis cells for the double purpose of carrying electric charges between electrodes and separating the products formed at each electrode. The purpose of this chapter is to provide an overview of chlor-alkali technology and associated cell separators. After a brief historical review of the chlor-alkali process, the main reaction characteristics (thermodynamics, cell reactions and kinetics) are detailed in Section 9.1. Main chlor-alkali technologies are described in Section 9.2. Main cell separators are described in Section 9.3 (diaphragm materials) and in Section 9.4 (membrane materials). Some improved electrolysis concepts are described in Section 9.5. 

This chapter gives an overview of the chlor-alkali industry in Australia and examines the background to the decision to replace the mercury cell plants. It then describes the new plants, their technical and safety features and the process used to arrive at the selection of the technology supplier. 

In spite of their importance, relatively little information exists in the literature concerning the fundamental physicochemical properties of these membranes. This is due both to their proprietary nature and to the rapid growth of the technology. Also, what information is available is dispersed in a wide range of sources, ranging from the literature specializing in macromolecules to that devoted to the chlor-alkali industry. This work attempts to provide, in one volume, an overview of both the fundamental properties and the technological aspects of the field. 

Today, the membrane process is state of the art. Its energy demand is about 25-30 % lower its operation is easier, safer, more efficient and flexible and needs less maintenance in comparison with the traditional processes, without environmental problems of asbestos or mercury (see entry Chlorine and Caustic Technology, Overview and Traditicaial Processes ). Investment costs and space requirements are significantly reduced. AU new chlor-alkali electrolysis plants use the membrane process since about 20 years. 

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