Nomenclature
The nomenclature is the same as in Chapter 6 (9),except that solvent-free streams are denoted by double-primes instead of boldface type.
\f=E,
literature Cited
/ W
Figure 2. In the absence of extract reflux the locations of points independent of any raffinate reflux
where ‘YpR and N w are the ordinates of points Px and W in Figure 1. This shows that the solvent requirements are identical in the two cases. Operation with a n d without Raffinate Reflux
Refer to figures 6.26 and 6.63 ( 9 ) : Material balances on each ideal stage lead to the same operating or difference point, W , both with and without raffinate reflux. When pure extracting solvent is used W j s on the vertical through PR, as shown on the Janecke diagram, Figure 2. [UT becomes the symbol 0, PR = R,, and Ef is called El when operating without reflux ( 9 ) ] Now F” - E“, = W”, and since points F and Ej (or E l ) are in the same respective positions both with and without raffinate reflux, this means that
800
W and M are
point 11; must also be in the same place in both cases (Figure 2). Consequently the total number of ideal stages needed must be the same both with and without raffinate reflux. If pure extracting solvent is used, a solvent-free material balance aver the whole plant is
fi”
Ef”+ PR’f
1
=
=
M“iV.\r - F“Nr
where N M and iVP are the ordinates of points M and F i n Figure 2. This shows that the solvent requirements are identical in the two cases.
INDUSTRIAL AND ENGINEERNO CHEMISTRY
for review January 12, 1961 RECEIVED ACCEPTED March 30, 1961
M’f
Since points E, (or E l ) ,PR and F have the same respective positions on Figure 2 both with and without raffinate reflux, this means that point M is also in the same place in both cases. A solvent balance yields
S
(l),Brown, G. G., others, “Unit Operations,” pp. 301-2, Wiley, New York, 1950. (2) “Chemical Engineers Handbook” (J. H. Perry, editor), pp. 717-18, 733-9, McGraw-Hill. New York. 1950. ( 3 ) Elgin, J. d,Chem. &’ Met. Eng. 49, NO. 5, 110-16 (1942). (4) Foust, A. S.,others, “Principles of Unit Operations,’’ pp. 51? 54, 55, Wiley, New- York, 1960. (5) Larian, M. G., “Fundamentals of Chemical Engineering Operations,” pp. 452-7, Prentice-Hall, Englewood Cliffs, N. J., 1958. (6) Maloney, J. O., Schubert, A. E., Trans. Am. 2nd. Chem. &grs. 36, 741-57 (1940). (7) McCabe, W. L., Smith, J. CI., ”Unit Operations of Chemical Engineering,” pp. 787-95, McGraw-Hill, New York 1956. (8) Sherivood, T. K., Pigford, K. L., “Absorption and Extraction,” pp. 394-5 McGraw--Hill,New York, 1952. (9) Trevbal, R. E., “Liquid Extraction:” pp. 176-94, 196-8, McGraw-Hill, Kew York, 1351. (10) Treybal, R. E., “Mass Transfer Operations,’’ pp. 412-25, McGraw-Hill, New York. 1955. (11) Varteressian, K. A,, Fenske. hf. R., IND. ENG.CHEM.28, 1353-60 (1936). (12) Wehner, J. F., A.2.Ck.E. Journal 5 , 406 (September 1959).
Correction Removing Carbon Monoxide from Ammonia Synthesis Gas I n this article by Holger C. Andersen and William J. Green [IND.ENG.CHEM. 53, 645 (1961)], there is a n error in the identification of Figures 1 and 2, page 646. T h e graphs above the captions should be interchanged.
