Flue gas desulfurization processes

ADVACATE A flue-gas desulfurization process, similar to CZD, but using a suspension of fly-ash instead of lime. Developed by the University of Texas, the U.S. Environmental Protection Agency, and Acurex Corporation. 

ASARCO [American Smelting and Refining Company] This large metallurgical company has given its name to a flue-gas desulfurization process in which the sulfur dioxide is absorbed in dimethylaniline and subsequently desorbed at a higher temperature. Operated in California, Tennessee, and Norway. 

Battersea A pioneering flue-gas desulfurization process, operated at Battersea power station, London, from 1931 until the station was closed. The flue-gases were washed with water from the River Thames whose natural alkalinity was augmented by chalk slurry. One of the problems of this process was cooling of the stack gases, which caused the plume to descend on the neighborhood. 

Bergbau-Forschung/Uhde A flue-gas desulfurization process that uses a movable bed of hot coke. Operated in a power station in Arzberg, Germany, since 1987. 

Bischoff A flue-gas desulfurization process. A slurried mixture of lime and limestone is sprayed into the gas in a spray tower. The calcium sulfite in the product is oxidized by air to calcium sulfate. Used in Europe in the 1980 s. Lurgi Bishoff is a part of the Lurgi group. The process is offered by Lentjes, Germany, a subsidiary of Lurgi. 

Cansolv A "flue-gas desulfurization process based on the selective absorption of sulfur dioxide in certain amine-based organic solvents. Developed by Union Carbide Corporation the first plant was planned for startup at Newburgh, IN, in 1994. See HS. 

ChemicoB-Basic A flue-gas desulfurization process using magnesium oxide slurry. 

CONOSOX A complex flue-gas desulfurization process using potassium carbonate solution as the wet scrubbing medium. The product potassium bisulfite is converted to potassium thiosulfate and then reduced with carbon monoxide to potassium carbonate for re-use. The sulfur is recovered as hydrogen sulfide, which is converted to elemental sulfur by the Claus process. Developed by the Conoco Coal Development Company and piloted in 1986. 

CZD [Combined zone dispersion] Also called Bechtel CZD. A flue-gas desulfurization process in which a slurry of a chemically reactive form of lime (pressure-hydrated dolomitic lime) is injected into the duct. The water in the slurry evaporates quickly and the solid product is collected downstream in an electrostatic precipitator. Developed by Bechtel International in the late 1980s, intended for retrofitting to an existing plant. 

DAP-Mn Also called the Manganese Dioxide Process. A flue-gas desulfurization process using a fluidized bed of manganese dioxide, which becomes converted to manganous sulfate. The adsorbent is regenerated with ammonia. 

Desox A flue-gas desulfurization process in which limestone slurry absorbs the sulfur dioxide, forming calcium sulfite. This is then oxidized to saleable gypsum ... 

Dowa A flue-gas desulfurization process in which the sulfur dioxide is absorbed in a basic aluminum sulfate solution. The product solution is oxidized with air and reacted with limestone to produce gypsum. Developed by the Dowa Mining Company, Japan, in the early 1980s. In 1986 it was in use in nine plants in Japan and the United States. 

Dual Alkali A flue-gas desulfurization process. The sulfur dioxide is absorbed in aqueous sodium hydroxide and partially oxidized, and this liquor is then treated with calcium hydroxide to regenerate the scrubbing solution and precipitate calcium sulfate. Developed by Combustion Equipment Associates and Arthur D. Little. 

ELCOX A flue-gas desulfurization process in which the sulfur dioxide is oxidized elec-trochemically to sulfuric acid, using an organometallic catalyst (e.g., cobalt phthalocyanine) adsorbed on activated carbon. Developed by the Central Laboratory of Electrochemical Power Sources, Sofia, Bulgaria. 

Flakt-Hydro A flue-gas desulfurization process which uses seawater as the scrubbing liquor. The pH of the effluent is raised with calcium hydroxide before it is discharged to sea. Developed by Norsk Viftefabrikk. Now owned by ABB Flakt Industri. As of 1996, 16 plants had been installed worldwide. 

Formate (2) A flue-gas desulfurization process. Potassium formate solution reduces the sulfur dioxide to thiosulfate, and then to hydrosulfide. 

FW-BF [Foster Wheeler-Bergbau-Forschung] A dry flue-gas desulfurization process that combines the sulfur removal system of Bergbau-Forschung, which uses a carbon adsorbent, with the Foster-Wheeler process for oxidizing adsorbed sulfur to sulfuric acid. 

HALT [Hydrate addition at low temperature] A flue-gas desulfurization process in which lime slurry is injected into the combustion gases after they have been cooled in the heat exchanger. Developed in Canada in the mid-1970s. 

Howden An early flue-gas desulfurization process using a lime or chalk slurry in wooden grid-packed towers. The calcium sulfate/sulfite waste product was intended for use in cement manufacture, but this was never commercialized. The key to the process was the use of a large excess of calcium sulfate in suspension in the scrubbing circuit, which minimized the deposition of scale on the equipment. The process was developed by Imperial Chemical Industries and James Howden Company in the 1930s and operated for several years at power stations at Fulham, London, and Tir John, South Wales, being finally abandoned during World War II. British Patents 420,539 433,039. 

Ionics A flue-gas desulfurization process using aqueous sodium hydroxide. The resulting sodium sulfate solution is electrolyzed to yield sodium hydroxide, sodium bisulfate, sulfuric acid, oxygen, and hydrogen. 

Ispra Mark 13A A flue-gas desulfurization process developed at the Joint Research Centre of the European Community at Ispra, Italy, from 1979. It uses a novel electrochemical method to regenerate the solution used for absorbing the sulfur dioxide. The products are concentrated sulfuric acid and hydrogen. The absorbent is a dilute aqueous solution of sulfuric and hydrobromic acids, containing a small amount of elemental bromine. Sulfur dioxide reacts with the bromine thus ... 

LIFAC [Limestone in-fumace and Added Calcium] A dry flue-gas desulfurization process in which limestone is injected into the lumace and calcium hydroxide is injected after it. Developed by Tampella in 1984 and used in a power station in Finland. A demonstration plant was built for Saskatchewan Power, Canada, in 1990. 

LIMB [Lime/limestone injection into a multi-stage burner] A flue-gas desulfurization process used in Germany and Finland. Dry, ground limestone is injected directly into the combustion chamber. This reacts with the sulfur dioxide, and the dry particulate product is collected downstream together with the ash. The process is suitable only for those systems which limit the maximum combustion temperature by staging, in order to minimize the production of oxides of nitrogen. 

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. 

Nahcolite A flue-gas desulfurization process. Nahcolite is a mineral containing 70 to 90 percent sodium bicarbonate, which is found in Colorado. In this process, the powdered nahcolite is injected into the baghouse and the following reaction occurs ... 

NEUTREC A flue-gas desulfurization process, intended for treating the waste gases from incinerators for municipal, hospital, and industrial wastes. Sodium bicarbonate, optionally mixed with active carbon, is injected into the gases after the usual bag filter, and the solid products are removed in a second bag filter. Sodium compounds can be recovered from the product for reuse, and ary toxic compounds disposed of separately. Developed by Solvay and operated in Europe since 1991. 

Poz-O-Tec A flue-gas desulfurization process which produces a fibrous form of gypsum, convenient for disposal. In a demonstration project, an artificial reef was built from the product in the Atlantic Ocean near Fire Island, New York. Developed by IU Conversion Systems, Philadelphia, PA. 

Reinluft A flue-gas desulfurization process using coke. The carbon acts as a catalyst for the oxidation of the sulfur dioxide to sulfur trioxide in the presence of water, and the sulfur trioxide is retained on the coke. The coke is regenerated in another vessel by heating with a hot gas stream, which reduces the sulfur trioxide back to sulfur dioxide and expels it for use in sulfuric acid manufacture. The key to this process is the inexpensive adsorbent. Developed by Reinluft GmbH and Chemiebau Dr. A. Zieren GmbH, and marketed as the Reinluft (Clean Air) Process. Four plants had been built by 1985. 

SDA [Spray drier absorber] A flue-gas desulfurization process in which an aqueous suspension of lime is injected into a spray drier. Basically similar to DRYPAC. Developed by Niro Atomiser, Denmark. In 1986 it was in use in 16 plants in Austria, Denmark, Germany, Italy, Sweden, China, and the United States. 

SFGD [Shell flue gas desulfurization] A flue-gas desulfurization process using a fixed bed of copper on alumina. The sulfur dioxide is desorbed with a reducing gas. 

SHU [Saarberg-Holter-Lurgi] A flue-gas desulfurization process using wet limestone as the sembbing medium, assisted by the addition of dilute formic acid. Developed by the companies named, and used in 11 power stations in Germany and Turkey in 1987. 

SOXAL A flue-gas desulfurization process, basically similar to the Wellman-Lord process but regenerating the bisulfite solution in a membrane electrochemical cell. Developed by Allied Signal Group and piloted at the Florida Power Light Company, Miami, FL, in 1991. A larger demonstration plant was planned for Dunkirk, New York. 

Stackpol 150 Also known as IFP Stackpol 150. A flue-gas desulfurization process. The sulfur dioxide is removed by scrubbing with aqueous ammonia, and the sulfur is then recovered by a four-stage process. Developed by the Institut Frangais du Petrole. 

Stone Webster/Ionics A flue-gas desulfurization process in which the sulfur dioxide is absorbed in aqueous sodium hydroxide, forming sodium sulfite and bisulfite, the sulfur dioxide is liberated by the addition of sulfuric acid, and the reagents are regenerated electrolyti-cally. Designed by Stone Webster Engineering Corporation and Ionics Incorporated and operated in a demonstration plant in Milwaukee in 1974 but not yet commercialized. 

SULF-X [Sulfur extraction] A regenerable flue-gas desulfurization process in which the sulfur dioxide is absorbed by aqueous sodium sulfide in a bed packed with pyrite. Ferrous sulfate is produced this is removed by centrifugation and calcined with coke and fresh pyrite. Sulfur vapor is evolved and condensed, and the residue is re-used in the scrubber. Piloted in the mid-1980s. Not to be confused with Sulfex or Sulph-X. 

Sultrol A flue-gas desulfurization process, similar to the Flakt-Boliden process, but using potassium citrate instead of sodium citrate. Developed by Pfizer and announced in 1985, but not known to have been commercialized. 

Walther Also called Walther Ammonia. A flue-gas desulfurization process in which the gas is scrubbed with aqueous ammonia. Two scrubbing stages are used, operating at different pH values. The by-product is suitable for use as a fertilizer. Developed and licensed by Walther Company. Two plants were operating in Germany in 1987, one of which was experiencing serious operational problems. 

Stuebner, D.O. "Evaluation of Regenerable Flue Gas Desulfurization Process, Vol. I. Final Report," Radian Corp., Austin, XX, EPRI FP-722, March 1976. 

Solution Equilibria in Aqueous Flue Gas Desulfurization Processes... 

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