Westvaco process

SO2 Sorber. In applying of the Westvaco process to boilers, Claus units, smelters, etc, a variety of waste gases will be encountered. Therefore, to estimate reactor size differential, sorption rate studies were made with simulated flue gases. Stepwise regression techniques were then applied to obtain a rate expression (Equation 5). A more detailed discussion of the rate models considered and the quality flt of the model... 

A related procedure is used in the Westvaco process, except that sulfur dioxide is catalytically oxidized to sulfur trioxide using activated carbon at 75-150°C. The sulfur trioxide is then hydrated to sulfuric acid which is absorbed onto the active carbon [36]. Sulfur recovery from the sulfuric acid is as sulfur dioxide, which is formed in a regenerator by raising the temperature of the carbon and adding hydrogen sulfide. 

Three other processes that electrolytically convert HC1 to Cf using metal chloride catalyst are the Schroeder process, using NiCf the Westvaco process, using CuC and the South African process, using MnC. None of these processes is commercial. The Schroeder process illustrates the principles involved in these technologies. The Schroeder process is cyclic and involves two steps. The metal chloride is electrolyzed to produce the metal and chlorine ... 

This approach to the conversion of HCl is known as the Westvaco process. The slow oxidation of cuprous chloride is its major disadvantage. Increasing the temperature to speed up the reaction also increases the vaporization of HCl and water. 

Hine and coworkers studied this electrolysis with oxygen-depolarized graphite cathodes [41]. This combination is known as the Kyoto cell, and it operates with either air or oxygen supplied to the cathode compartment. The reactions are the same as in the Westvaco process, but the oxidation of cuprous chloride takes place in the cell rather than in an external reactor. 

The Westvaco process is a dormant, experimental, activated carbon process that has a removal step somewhat similar to that of the Mitsui-BF process, but a regeneration step that does not consume carbon. The sulfuric acid adsorbed on the carbon is reacted with hydrogen sulfide to produce elemental sulfur and water. Part of the sulfur produced is reacted with hydrogen to produce the necessary hydrogen sulfide. Development was discontinued due to the high cost of activated carbon relative to activated coke (Radian, 1977 Behrens et al., 1984 Spears, 1992). 

Westvaco Corporation is reported to be the only significant producer of lignosulfonate utilising this process. 

C-21 dicarboxyhc acids are produced by Westvaco Corporation in Charleston, South Carolina in multimillion kg quantities. The process involves reaction of tall oil fatty acids (TOFA) (containing about 50% oleic acid and 50% hnoleic acid) with acryhc acid [79-10-7] and iodine at 220—250°C for about 2 hours (90). A yield of C-21 as high as 42% was reported. The function of the iodine is apparendy to conjugate the double bond in linoleic acid, after which the acryhc acid adds via a Diels-Alder type reaction to form the cycHc reaction product. Other catalysts have been described and include clay (91), palladium, and sulfur dioxide (92). After the reaction is complete, the unreacted oleic acid is removed by distillation, and the cmde C-21 diacid can be further purified by thin film distillation or molecular distillation. 

Westvaco (1) A variation of the Claus process for removing hydrogen sulfide from gas streams, in which the sulfur dioxide is catalytically oxidized to sulfur trioxide over activated... 

Westvaco (2) A process proposed for making chlorine by electrolyzing aqueous copper chloride. Invented in 1928 by F. S. Low at Chlorine Products, New York. Piloted by Westvaco in the 1940s, but not commercialized. 

A number of inoiganic pollutants are removable by TSA processes. One of the major pollutants requiring removal is S02 from flue gases and from sulfuric acid plant tail gases. The Sulfacid and Hitachi fixed-bed processes, the Sumitomo and BF moving-bed processes, and the Westvaco fluidized-bed process all use activated carbon adsorbents for proven S02 removal (58). Zeolites with high acid resistance, such as mordenite and clinoptilolite, have proven to be effective adsorbents for dry S02 removal from sulfuric acid tail gas (59), and special zeolite adsorbents have been incorporated into the UOP PURASIV S process for this application (54). 

Using active carbons and some other carbonic adsorbents, several processes have been elaborated to output commercial products (sulphuric acid, sulphur, and sulphur dioxide), Reinluft (FRG), Hitashi (Japan), and Westvaco (USA). However, because of the deficit and high cost of adsorbents, these processes may be recommended only for purification of small volumes of ejected gases. Recently, the methods using natural acid-stable clinoptilolite- and mordenite-type zeolites as adsorbents have been introduced into industry. It is safe to say, however that general drawback of all granular physical adsorbents is their low sorption activity at a sufficiently low concentration of SO2 n g comparatively high aerodynamic resistance. 

Westvaco has, over the past six years, developed a sulfur dioxide removal process using activated carbon that operates after the usual low... 

Pilot studies are currently underway on all process steps at the 20,000 ft /hr flue gas level. While concluding these studies, the reactors are being integrated to study cyclic operation and evaluate long-term effects in continuous equipment. Following these pilot studies installation of a 10 MW, 20,000 ft /min or larger prototype on a coal-fired boiler is projected by Westvaco. This size is also approximately comparable to expected gas volumes from a 200 ton/day Claus unit. 

Pan et al. [34] used the nonlocal density functional theory (DFT) [35] and the three-process Langmuir model (TPLM) [36] to predict the adsorption heats of propane and butane on carbon and compared these results with experimental data determined from isotherms measured on BAX-activated carbon (Westvaco) in the 297—333 K temperature interval. Both models agreed in showing that the adsorption heat for butane was c. 10 kj/mol higher than that of propane at the same loading. The satisfactory agreement found prompted the authors to propose the use of the DFT method as it requires only one experimental isotherm in contrast with the numerous isotherms required by the classic technique. 

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