Sulfur Westinghouse

In the initial thiocyanate-complex Hquid—Hquid extraction process (42,43), the thiocyanate complexes of hafnium and zirconium were extracted with ether from a dilute sulfuric acid solution of zirconium and hafnium to obtain hafnium. This process was modified in 1949—1950 by an Oak Ridge team and is stiH used in the United States. A solution of thiocyanic acid in methyl isobutyl ketone (MIBK) is used to extract hafnium preferentially from a concentrated zirconium—hafnium oxide chloride solution which also contains thiocyanic acid. The separated metals are recovered by precipitation as basic zirconium sulfate and hydrous hafnium oxide, respectively, and calcined to the oxide (44,45). This process is used by Teledyne Wah Chang Albany Corporation and Western Zirconium Division of Westinghouse, and was used by Carbomndum Metals Company, Reactive Metals Inc., AMAX Specialty Metals, Toyo Zirconium in Japan, and Pechiney Ugine Kuhlmann in France. 

Westinghouse A proposed thermochemical process for decomposing water to oxygen and hydrogen by electrolysis, coupled with the high-temperature decomposition of sulfuric acid ... 

Carty R, Cox K, Punk J, Soliman M, Conger W (1977) Process sensitivity studies of the Westinghouse sulfur cycle... 

Westinghouse Electric Corporation (1980), A Study on the Electrolysis of Sulfur Dioxide and Water for the Sulfur Cycle Hydrogen Production Process, AESD-TME-3043, July. 

Brecher, L.E., S. Spewock, C.J. Warde (1977), The Westinghouse Sulfur Cycle for the Thermochemical Decomposition of Water , International Journal of Hydrogen Energy, Vol. 2, pp. 7-15, Pergamon Press. 

Farbman, G. H. NASA CR-134976 "The Conceptual Design of an Integrated Nuclear Hydrogen Production Plan Using the Sulfur Cycle Water Decomposition System" Westinghouse Electric Corporation April 1976. 

Farbman, G. H. Krasicki, B. R. Hardman, C. C. Lin, S. S. Parker, G. H. EPRI-EM-789 "Economic Comparison of Hydrogen Production Using Sulfuric Acid Electrolysis and Sulfur Cycle Water Decomposition" March 1978 prepared by Westinghouse AESD for Electric Power Research Institute Palo Alto, California 94304. 

Due to high T and 2 law efficiencies of sulfuric acid based cycles, to date, more than 20 sulfuric acid and/or metal sulfate decomposition based TCWSCs have been reported. Despite difficulties that challenge efficient electrolytic oxidation of sulfur dioxide (SO2), the Westinghouse hybrid cycle still remains as one of the most studied TCWSCs. The Westinghouse cycle is as follows [14] ... 

Brecher, L.E., Spewock, S., et al., Westinghouse Sulfur Cycle for the Thermochentucal Decomposition of Water, Proceedings of the V World Hydrogen Energy Conf, 1 9A, 1-16,1976. 

The system (Figure 12) is based on sulfuric acid (H2SO4) synthesis and decomposition process (the Westinghouse process) developed earlier. The sulfur trioxide (SO3) decomposition process is facilitated by electrolysis with ionic oxygen conductive solid electrolyte to reduce the operation temperature 200°C-300°C lower than the Westinghouse process. 

The Westinghouse cycle is a variant of sulfur—iodine and is a hybrid concept that requires both thermal and electrical energy. When the product of reaction (4.31) is cooled, sulfurous acid is formed and this is electrolyzed at around 80 °C to produce hydrogen and sulfuric acid for recycling, i.e.,... 

On the other hand, the test data available to date suggest that a number of matters remain to be resolved before this cycle can realistically be considered as a serious competitor to the sulfur—iodine and Westinghouse alternatives. Further experimental and engineering development work is required to address the following issues ... 

Fig. 2-10 Diagram of the Westinghouse sulfuric acid hybrid cycle, from [20]... 

In the Westinghouse sulfuric acid hybrid cycle shown in Fig. 2-10 (see also appendix A.3.2.), HTGR heat will be used for the H2SO4 decomposition step. Both high-temperature and electric steps have been experimentally investigated at the Research Center Julich. The above hybrid cycle has undergone a detailed balance and cost analysis already in a plant design based on nuclear power [8]. 

Thermochemical hybrid cycles offer the possibility of running low-temperature reactions on electricity. The expectations for realization of hybrid processes are similar to those for purely thermochemical processes. Various hybrid processes are energetically possible, but not always practicable. Important criteria are the minimum voltage for the electrolysis step, realizability, efficiency. The sulfuric acid hybrid or Westinghouse process is expected to reduce material streams as compared with the IS process. The electric energy demand here is a factor of 7 (in reality 3 - 4) lower than in the electrolytic water splitting process. Technological improvements are still possible. 

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