Membrane cell technology

A summary of the current membrane cell technologies is provided in Table 13. 

Table 13. Summary of Current Membrane Cell Technologies...

In 1998, Krupp Uhde became the sole owner of Single Element Technology and continues to put great effort into the further development of membrane cell technology for different electrolysis applications. With a new patent [4] for improved Single Element Technology, Krupp Uhde is ready for the future. 

J. L. Hurst, Implementing Membrane Cell Technology W ithin OxyChem Manufacturing. International Symposium on Chlor—Alkali Industry, Tokyo, Japan,... 

Uranous nitrate [U(N03)4] solution is used for the quantitative reduction of plutonium from loaded tributyl phosphate (TBP) phase [8]. Membrane cell technology was investigated for the production of 100% uranous nitrate solution [9], which is to be used in the partition cycle of the PUREX process in the fuel reprocessing plant. The membranes used hitherto have suffered from mechanical instability. A study was carried out at the BARC to obtain 100% uranous nitrate solution using a membrane-based electrolytic cell. The membrane used in this study was a thin polymer film reinforced with a Teflon fabric. The film was used as a separator between the anolyte and catholyte chambers, which are made of perfluorinated polymers, thus offering high thermal and chemical stability. 

Important vendors of membrane cell technology are Asahi-Kasei, Chlorine Engineers, ELTECH, and INEOS and UhdeNora. 

Other remaining technical concerns with membrane cells relate to somewhat lower current efficiencies and to relatively short membrane lifetimes. At present, this is limited to 2-3 year of operation when coupled to much more careful brine pretreatment than is required for conventional asbestos diaphragm cells. A combination of mercury cell and membrane cell technologies has been recently tested for commercial feasibility [19]. The economics of the three primary chloralkali technologies have also been reviewed [20]. 

Commercial application of membrane cell technology began in 1975 with the installation of the Nobeoka No 1 (Japan) using Asahi Chemical Co. electrolyzers, Reed Paper (Canada) using Hooker MX electrolyzers and American Can of Canada (Canada) using Ionics Chloromate electrolyzers. By the end of 1982 world capa-... 

Further development of the "Zero Gap" membrane cell technology by Asahi Glass Co., called AZEC, is reported to have achieved at laboratory scale an electrolytic power consumption of 1950 KWH/M ton NaOH at 2 KA/M current density and 35% NaOH and at a current density of 4 KA/M the power consumption is 2140 KWH/M ton NaOH (78). 

Development of these new zero gap membrane cell electrolyzers represents a major new approach in the membrane cell technology and promises to provide even more rapid development in this quiet revolution of the membrane cell chlor alkali process. 

Klamp, K. Lohrberg G. "Membrane Cell Technology-View of an... 

Low tonnage electrolyzers, which are typically needed for wastewater treatment purposes use the membrane cell technology for the manufacture of chlorine [51]. Unlike mercury or diaphragm cells, the membrane technology is more suited for intermittent production of chlorine. 

The process energy consumption in a membrane cell is small compared to diaphragm and mercury cell operations and the membrane cell caustic is of the same quality as mercury cell caustic. Hence, the membrane cell technology is recognized as the most economical and preferred method for producing chlorine and caustic (see Section 6 for additional details regarding membrane cells). 

Engineering Design Aspects of Ion-Exchange Membrane Cell Technology... 

The advent of membrane cells is largely dictated by environmental regulations related to the hazardous nature of mercury effluents (from mercury cell process) and asbestos (used in diaphragm cell technology).37 However, there are several advantages offered by the membrane cell technology as noted below. 

After DuPont introduced Nafion membranes. Diamond Shamrock intensified its research efforts in membrane-cell technology. Initial research tests with the membranes began in 1970 using laboratory cells. In 1972, a commercial-size electrolyzer and pilot plant were placed in operation in Painesville, Ohio. Four years later, a 20-ton per day demonstration plant was built in Muscle Shoals, Alabama. Hiis unit was integrated with an existing mercury-cell plant. 

Like Diamond, Hooker Chemicals demonstrated an interest in ion-exchange membranes since the mid-1940s. S.G. Osborne etal. of Hooker Chemical Corporation hold the original patent for the first membrane cell [36]. This patent was filed on January 23,1952. With this patent. Hooker embarked upon a major development program until 1957. Following a period of relative inactivity, the Nafion membrane rekindled interest in membrane-cell technology. 

Since then, several membrane-cell technologies were developed in Japan, as a pollution-free chlor-alkali process. Japanese contributions include composite membranes and several electrolyzer designs. Japan was the first major chlorine producing country to convert entirely to membrane cell technology. As of January 2003, 35% of world production of chlorine is by membrane-cell technology, generating 52,000 metric tons caustic/day. 

In 2002, approximately 67% of the chlorine in the United Sates was produced using the diaphragm-cell technology, 20% by the membrane-cell technology, and 10% by the mercury-cell technology. Five companies—Dow Chemical, Occidental Chemical Corporation, PPG Industries, Olin Corporation, and Formosa Plastics Corporation— manufacture 79% of the chlorine. Twenty-eight percent of the total US chlorine production was by Dow Chemical, whereas twenty-two percent of the production was by Occidental Chemical. PPG, Olin, and Formosa Plastics produce 12%, 9%, and 7% of the chlorine production in the United States, respectively. 

A. Nidola and R. Schira. Deactivation of Low Hydrogen Overvoltage Cathodes in Chlor-Alkali Membrane Cell Technology by Metallic Impurities, In M.M. Silver and E.M. Spore (eds), Advatutes in the Chlor-Alkali and Chlorate Industry, The Electrochemical Society Inc., Princeton, NJ (1984), p. 206. 

In the early 1990s, membrane-cell technology was available from seven or eight suppliers. However, there are now only five suppliers of ion-exchange membrane cells. They are Asahi Kasei, Chlorine Engineers, ELTECH, Uhde, and INEOS Chlor (formerly ICI). Both monopolar and bipolar cells are available from these cell manufacturers, but bipolar cells have become more popular in recent years. 

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