Molten carbonate process

The Chemistry of the Molten Carbonate Process for Sulfur Oxides Removal from Stack Gases... 

In the molten carbonate process a molten eutectic mixture of lithium, sodium, and potassium carbonates removes sulfur oxides from power plant stack gases. The resulting molten solution of alkali metal sulfites, sulfates, and unreacted car bonate is regenerated in a two-step process to the alkali carbonate for recycling. Hydrogen sulfide, which is evolved in the regeneration step, is converted to sulfur in a conventional Claus plant. A 10 MW pilot plant of the process has been constructed at the Consolidated Edison Arthur KiU Station on Staten Island, and startup is underway. 

In the molten carbonate process, a molten eutectic mixture of lithium, sodium, and potassium carbonates is used to scrub the power plant gas stream. The sulfur oxides in the gas stream react with the carbonates to form sulfites and sulfates which remain dissolved in excess unreacted carbonate melt. The molten carbonate-sulfite-sulfate mixture is then... 

Figure 1. Molten carbonate process flow diagram...

Molten carbonate process pilot plant at completion of construction, Mar. 30,1973... 

A thorough engineering and economic evaluation of the molten carbonate process was completed by Singmaster and Breyer in 1970, under contract to EPA (8). For the same plant situation, their cost estimates (based on 1970 dollars) were 16.81/kW for the capital investment (not including the Claus plant) and 0.95 mills/kW hr for operating costs without by-product credit. 

The only process in this category that has received significant research and development attention is the Molten Carbonate Process developed by Rockwell International (Oldenkamp and Margolin, 1969 Katz and Oldenkamp, 1969). Although the process has not been commercialized, it is of interest because of the unique technology involved. Its potential advantages are the ability to treat the flue gas at an elevated temperature without adding water vapor and the production of a useful byproduct (sulfur). 

The molten carbonate process is not widely adopted for the fabrication of IiCo02 fUm, and information about this process is limited. Todate, it has only been reported by Uchida et al. [139, 140], A preferentially (003)-oriented LiCo02 thin-film was obtained by oxidation of a thin cobalt film i n molten Li + K carbonate (62 38 mol%) onto a gold substrate at 923 K under an atmosphere of O2 and CO2 in a ratio of 9 to 1. The thickness of the IiCo02 film depends on the oxidation period. The difiusion... 

W. He and Kas Hemmes, Operating characteristics of a reformer for molten carbonate fuel-cell power-generation systems. Fuel Processing Technology, 67 (2000) 61. 

Molten Carbonate A flue-gas desulfurization process in which the sulfur dioxide contacts a molten mixture of inorganic carbonates. These are converted to sulfates and sulfides and then reduced to hydrogen sulfide, which is treated in a Claus kiln. The advantage of this process over most others is that it does not cool the flue-gases. Not commercialized. Oldenkamp, R. D. and Margolin, E. D., Chem. Eng. Prog, 1969, 65(11), 73. 

MCFC Molten carbonate 650 48-56 High efficiency, internal fuel processing, high-grade waste heat Electrolyte instability, short operating life, C02 recycling Power production, cogeneration... 

Electrolyte management, that is, the control over the optimum distribution of molten carbonate electrolyte in the different cell components, is critical for achieving high performance and endurance with MCFCs. Various processes (i.e., consumption by corrosion reactions, potential driven migration, creepage of salt and salt vaporization) occur, all of which contribute to the redistribution of molten carbonate in MCFCs these aspects are discussed by Maru et al. (4) and Kunz (5). 

A dense and electronically insulating layer of LiA102 is not suitable for providing corrosion resistance to the cell current collectors because these components must remain electrically conductive. The typical materials used for this application are 316 stainless steel and chromium plated stainless steels. However, materials with better corrosion resistance are required for longterm operation of MCFCs. Research is continuing to understand the corrosion processes of chromium in molten carbonate salts under both fuel gas and oxidizing gas environments (23,25) and to identify improved alloys (29) for MCFCs. Stainless steels such as Type 310 and 446 have demonstrated better corrosion resistance than Type 316 in corrosion tests (29). 

Direct coal fuel cells were also tried, using molten carbonate as the electrolyte [6], However, ash formation, poor conductivity, and technical problems in continuously feeding the fuel made the process impractical and uneconomical. The subsequent successful development of the internal combustion engine, and the... 

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