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INDUSTRIAL AND ENGINEERING CHEMISTRY
reduction rates and smooth operation, the temperature of the hot zone should not be less than 1300’ C. The reduction of sulfur dioxide by means of carbon monoxide or oxysulfide is fast with any kind of catalyzing surface above 800’ C. At lower temperatures (250” to 500’ C.) alumina in the slightly hydrated and acid-soluble form is an efficient catalyst, and the reaction appears to be of the first order. Acknowledgment The writer wishes to express his appreciation of the valuable assistance rendered by R. M. B. Roome, J. Melville, G. S. Ortner, and J. H. Salter in conducting the experimental work upon which this paper is based.
Literature Cited (1) Clement, Adams, and Haskins, U. S. Bur. Mines, BUZZ.7 (1911). (2) Drakeley, T.J., J. SOC.Chem. Ind., 50, 319-30T (1931). (3) Haslam, R. T.,Hitchcock, F. L., and Rudow, E. W., IND. ENG. CHEM.,15, 119 (1923). (4) Haalam, R. T., and Russell, R. P., “Fuels and Their Combustion”, 1st ed., p. 338, New York, McGraw-Hill Book Co., 1926.
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(5) Ibid., p. 553. ( 6 ) Jones, J. H., King, J. G., and Sinnatt, F. S., Dept. Sci. Ind. Research (Brit.), Fuel Res. Tech. Papers 22 and 25 (1929-30). (7) Lepsoe, Robert, IND.ENG.CHEM.,30,92-100 (1938). (8) Perrott, G . St. J., and Kinney, S. P.,Trans. Am. Inst. Mining E w s . , 69,585 (1923). (9) Riley, H.L.,Chemistry &Industry. 58, 391-8 (1939). (10) Tu, C. M., Davis, H., and Hottel, H. C., IND.ENG.CHEM.,26, 756, Fig. 12 (1934).
... Correction In the previous paper on “Chemistry of Sulfur Dioxide Reactions”, which appeared in the January, 1938, issue of INDUSTRIAL AND ENGINEERING CHEMISTRY, some errors should be corrected : Page 95, table under “Monoatomic Sulfur” in the fourth column, the figure for /S/ should be 0.0085 instead of 0.085. Page 97, Table 111, the last figure under /CO/ should be 0.000005 instead of 0.055. Page 98, Table VI, the column headings “% CO” and “% COZ” should be transposed.
MULTICOMPONENT RECTIFICATION Optimum Feed-Plate Composition E. R. GILLILAND Massachusetts Institute of Technology, Cambridge, Mass.
I
The composition of the feed plate giving might be set to have a fixed conN DESIGNIKG rectification equipment for the continuseparation is centration of propane in the the fewest plates for a ous separation of a given bottoms and to recover a defi‘Onsidered for three different types Of feedmixture, the design engineer is nite fraction of the n-butane in often confronted with the probaction* equations are the feed with the bottoms; in lem of determining the plate on developed for these three cases, and they this case the key components serve as a method of estimating the optiwould be taken the same as bewhich the feed mixture should be fore, although the concentramum feed-plate composition. introduced into the rectifying column. In general, for given tion of the n-butane is not aboperating conditions the designer solutely fixed in the distillate, desires to introduce the feed to a plate having a composince the distribution of the intermediate component, isosition of the mixture to be separated, such that the total butane, would shift with the composition taken for the feed number of plates required for the separation will be a miniplate. I n general, little difficulty is found in selecting the mum; this will reduce the costs of the rectifying column. The two key components, although occasionally the problem of composition of the feed plate giving the fewest number of selection is somewhat involved but can usually be resolved plates will be termed the “optimum feed-plate Composition”, if the designer will analyze the fundamental purpose of the and a criterion of this composition will be of assistance to rectification in order to determine just what is fixed. the design engineer. I n performing the stepwise plate-to-plate calculations, The following derivations for the optimum feed-plate use is made of equilibrium data and of material balances composition will be on the basis of the two key components, expressed as the operating lines. Above the feed plate the where the “light key component” will be considered as the operating line1 is: most volatile component whose concentration is fixed in the bottoms, and the “heavy key component’’ will be considered as the least volatile component whose concentration is fixed in the overhead distillate. Thus, in the stabilization of a Below the feed the operating line is: gasoline containing saturated hydrocarbons ranging from methane UD to h e a w fractions. the design conditions mieht 1 Badger and MoCabe, “Elements of Chemical Engineering”. 2nd be set so as to have a’ definite concentratik of DroDane in ;he ed.. New York, McGraw-Hill Book Co., 1937; Robinson and Gilliland, “Elebottoms and of ,+butane in the distillate; in thi$ propane menta of Fractional Distillation”, 3rd ed., McGraw-Hill Book Co., 1939: be taken the light component and ” Walker, Lewia, MoAdams, and Gilliland. “Principles of Chemical Engineering”, 3rd ed., McGraw-Hill Book CO.. 1937. the heavy key component. Alternately, the conditions
