mg
_I__-
T. J. WALSH, CASE INSTITUTE
OF T E C H N O L O G Y , C L E V E L A N D 6, OHIO
The equations derived are similar to previous equations for the same purpose. Liquid-vapor phase relations in the hydrocarbon and petroleum field are frequently expressed in specialized terms. One of these is the “equilibrium constant, IC.” This constant is defined as the mole fraction of the component in the vapor divided by the mole fraction of the same component in the liquid, ( K = y/z) Poettmann and Mayland (186) extend the use of this approach to oils having normal boiling points as high a8 1000” F. The variables used are temperature, pressurel and characterization factor of the oil. Equilibrium constants are given by Stutzman and Brown (125) for components of natural gas at low temperatures. Another special method of defining phase relations for petroleum fractions is the equilibrium flash vaporization curve. which is particularly useful t o design engineers dealing with crude oil or heavy €ractions of the crude. Edmister and Pollock (37) present equilibrium flash vaporization data on 27 typical refinery stocks and develop a new correlation of these data with the A.S.T.M. distillation. This correlation is applioable in predicting the equilibrium flash vaporization curve at elevated temperatures. The sane curves are the subject of another correlation by Lamb and O’Brien (78). A correlation bt.tween the equilibrium flash vaporizadon curve and the true-boiling-point curve from pressures of 3000 to 10 mm. of mercury is presented by Okamoto and Van Winkle (88). The correlation appears satisfactory, although this relaLionship is generally not so exact as that between the curves having less fractionation. A nomograph for determining the relative volataity of two compounds is given by Frisho (46). This should be used only for the range ovcr which the vapors obey the ideal gas laws and not for the full range of pressure indicated on the scales. Equilibria data alone, however, are not enough to permit camplete calculations OR distillation equipment. It is also necessary to have the best possible data on the phyeical and t,hermodynamic propcrties of the system and its components. General thermodynamic data are discussed by Edmister (36) and by Kobe and Long (75). The relation of thermodynamic properties to molecular structure has been determined for several struct)ural groups in hydrocarbons b s Souders et al. (128). Data on particular compounds are available for benzene: ( l o o ) , is* propyl alcohol (@), n-butane (IO?), 1-hutenc and 1-propene (P16),light hydrocarbons (IOd),tars and pitches ( 6 7 ) , :ind 117 gases (281). Volumetric behavior of both liquid and vapor is important This is reported for benzene (@), propane (IO@, and propene (3Q). Correlations to be used in the absence of data are given by Dreisbach and Spencer (56), Obert (gYII Van Winkle ( I f B ) , Hanson (6@, and Rush and Gamson (If$). Viiiscosity-temperature data are an aid in predicting the eEciency of bubble-cap plates. The effect of structure on viscosity is determined by Sanderson (173)through the assistance of a viscosity-temperature number. Other correlations of assistance are those for Patent hea,t by Chu et al. (86)and Dreisbach (34),for activity coefficient corrwtion by Scheibel(116), for the relationship between vapor composi-
HE year 1949 appeals t o be one during which progress in high temperature distillation was concentrated on the accumulation of the basic data necessary for the utilization of the calculation techniyuee previously developed. This was desirable, as the theory had outstripped the data during recent years, leading in many cases to the performance of precise calculations based upon estimated data. With the information now appearing in the literature it is possible to use the more exact methods of designing and testing distillation equipment with confidence in the quantitative results of the CaIculations. Although the abundance of data reported overshadows the progress in the other phases of distillation, advances have been made in all aspects of this operation. Reviews of specialized phases of distillation are given by Rose (111, analytical distillation); Ortuno (1Of, rectifying columns); Hanson (69, still design); and Fowler (46, evolution of the Pquilibrium still). BASIC DATA
‘I’he data necessary to distillation calculations are expressed In many ways. Most direct are the vapor-liquid, z-y, equilibria data for a particular system. Data of this nature are given for butadienestyrene (132); ethylene chlorohydrin-cyciohexanc (68); nitromethane-trichloroethane (137); ethyl alcohol-met,hanolwater (63); ethyl alcohol-ethyl acetate-water (54); n-butane carbon dioxide (99); ethylene-butane (133); aeetone-ethylene chloride, acetonechloroform, propylene chloride-isopropyl axcohol, ethylene chloride-methyl alcohol, acetone-methyl alcohol, ethylene chloride-cyclohexane, toluene-ethylene chloride, and acetone-n-butyl alcohol (44); and 2,2,4trimetliylpentanemet,hylcyclohexane and 2,2,4-triz1et11ylpentane-toluene ( 4 7 ) . Data for the latter system are presented a t pressures of 14.7, 29.7, and 59.7 pounds per square inch absolute for use in the testing of equipment under pressure. The apparatus used in determining these data is suitable for pressures up to 600 pounds per square inch. More complete than the 2-y data are the enthalpy-concentration, H-x and H-y,data presented by Tyner (198)for the system hydrogen fluoride-water. These data are a t 1 atmosphere pressure. Equilibria data of binary systems can be calculated from azeotrope data using the methods described by Carlson and Colburn (83). Values of aseotropic composition and temperature are now widely available. Especially to be noted is the 2272-system supplement to Horsley’s Table of Azeotropes and Nonaeeotropes (66). Leeat, in a series of reports (78-82) also gives data on azeotropic systems of many types. Included smong these systems are several azeotropes formed between compounds containing the same functional groups. This behavior, if found to be common, will invalidate the suggestion Gf Scheibel (114) for predicting the formation of azeotropes. This suggestion is based upon the generalization that members of a homologous series do not form azeotropes. Azeotropes of toluene are reported by Marschner and Cropper (as), of m- and p-cresol by Othmer et al. (IO@, and of diborane by LlcCarty (86). Li and Coull(83) present. a method of predicting ternary system data from the data for the binary pairs of the system components.
32
January 1950
rNDUSTRIAL AND ENGINEERING CHEMISTRY
tion and solution properties by Othmer and Gilmont (IO@, and for bubble and dew points of benzene-toluene-xylene mixtures by Chetrick (24). INDUSTRIAL DISTILLATIONS
A
LI
d
The industrial applications of distillation oxygen are discussed by Bliss and Dodge the thermodynamics of the air fractionating towers. Continuous stills are now being used in the production of peppermint oil. A description of this operation is given by Bloomberg (14). Diffioulty in the removal of color from commercial naphthenic acids was investigated by Littmann and Xlote (84). The .of color cannot be removed from the acid by distillation on may be connected with the structure of the acid. Feeding a column with superheated vapors may be practical if provisions are made €or stripping the reflux just above the feed tray, is the conclusion of Volokh (131). Material and heat balances are uaed in studying this effect. The operational behavior of large bubble-cap columns is always of interest to designers and operators of equipment. The pressure drop through fractionating towers is found by Eld (38) to correlate with vapor density and vapor velocity. An equation and a nomograph are presented t o enable the calculation of this faator in tower design. Several examples show checks between the calculated values and field data. Hydraulic gradient across a large tray is another factor that (must be considered in plate layout. Properly designed trays keep the hydraulic gradient low even at high liquid loads and it $must never exceed the cap pressure drop a t any tray, Kemp and Pyle (72) rep0.d hydraulic gradient, pressure drop, and plate stability measurements for various arrangements of 3- and Much diameter bubble caps as a funotion of vapor rate, and seal depth. The plate variables are aumber of rows of caps, and skirt clearance. Pict aperation in a Lucite model column equivalent t o diameter tower are shown in the Kelloggrum (3). Normal tray operation, incipient flooding, and tray dumping are shown. Porcelain mushroom bubble caps were tested by Kirschbaum (?4). This equipment is reported t o tolerate high loading, prcvided the pIates are properly designed. Instrumentation of towers is discussed by Rector ( l o g ) , who explains why fractionators are controlled as they are. ‘Typical control systems are indicated by Boyd (29)and by Tivy (187). Somewhat different is the automatic control of a tower on the basis of dfierential absorption of light having a specific wave length (Anderson, 2). This would be applicable .to operation of a fractionating unit separating between close boiling compounds. Special design problems associated with the distillation of a ,polymerizable compound are discussed by Coulter (29). It is desirable that the residence time of the component in the column be less than the induction period of the polymerization reaction. The use of inhibitors is recommended and it is suggested that the .inhibitor pumps be installed in duplicate. DISTILLATION THEORY
The relationship existing among distillation, extractive distillation, and solvent extraction is discussed in two articles by Hibshman (6%’). From a thermodynamic viewpoint, aU three operations may be handled by parallel equations. If the separation selectivities are designated by CY for distillation, fl for tion, and y for extractive distillation, the relationship (a)( p ) =I y is approximately true for systems such as hydrocarbons. Incomplete correlation of distillation in wetted-wall columns with diffusion equations suggests t o Storrow (123s)that the diffusion equations may be inadequate. The technique used for -debmining composition by measurement of temperature
33
throughsut the column may be of interest to other investigators in this field. Equilibrium between vapor phase molecular species may be used to account for the behavior of formaldehyde solutions during distillation, The vapors apparently consist of an equilibrium mixture of formaldehyde and methylene glycol (Hall and Piret, 67). Bowman (27) proposes that distillation be considered as a means of separating an infinite number of compounds which need not all be different. When this conceptt is combined with material balances and ideal equilibrium relations, the fundamental equations are similar to those derived from the classical considerations. Distribution curves, defined by Harbert (61)as a plot of the fraction of a component in a tower feed that, appears in the overhead product us. the equilibrium constant (see above), are proposed as a method of simplifying multicomponent distillstion calculations. Murdoch (98) applies the calculus of finite differences t o systems having constant rAlative volatility and constant reflux. He derives algebraic equations for three- and four-component separations. The equations are presented as ing of multicomponent distillation. a t both high and low concentration of one component in a distillation tower is reported by Kirschbaum (78). This author refutes the assumption that heat- and masstransfer coefficients decrease with decreasing temperature difference. DISTILLATION CALCULATIONS
The McCabe-Thiele method of calculating a rectifying column is compared with the Ponchon method for the same problem by Diepen and Meyer is that the Ponchon method should be used nd they recommend that it be used in all ates a more complete knowledge of the system than the McCabe-Thiele approach. Another graphical approach to distillation problems is given h the form of eygograph (nomograph) by Yu and Coull (158). The algebraic approach is followed by Volkov and Zhavoronkov (130). Their equations are limited to conditions of‘ &xed reflux ratio and to systems obeying Raoult’s law. Batch distillations have long been difficult to handle, as the operation is occurring under unsteady state conditions. New relations for the minimum number of plates and for the minimum reflux ratio in batch operations are developed by Bowman and Cichelli (18). The concept of “pole height” to characterize a batch distillation curve is introduced. The pole height is defined as the product of the slope of the curve a t mid-height times the fraction of the charge remaining in the still pot. The equations developed are
;here n‘ is the minimum number of theoretical plates, R‘ is the minimum reflux ratio, 8 i s the pole height, and a is the relative volatility. Calculation of relative volatility from Margules’ constants for the system is proposed by Bergholm (IO). Other methods of determining relative volatility are also given. Sherwin (118) suggests that the calculation of theoretical trays under conditions of variable molal overflow be approximated by assuming that the molal enthalpy of the liquid is not affected by the vapor rate, and that the change in liquid enthalpy on rt tray is the same as on an adjacent tray. This leads to a solution that must be checked before proceeding to the next tray in tray-to-tray calculations. Key components are the basis of the methods of Smith and Dregser (119)and Chibseff (96). Both methods use a graphical
34
INDUSTRIAL AND ENGINEERING CHEMISTRY
solution of a key component separation as a method of determining the answer to a multicomponent problem. Bailey and Coates ( 7 ) recommend the Colburn correlation for minimum reflux ratio as a means of simplifying muIticomponent system calculations. In another article (8)this correlation plus Underwood's equations is used for determining the distribution of split key components. PACKED C O L U M N S
Several types of packing for laboratory and pilot plant columns have been reported and dcscribed. The efficiencies of the packrngs are given under a variety of conditions. Among the new packings are gauze rings formed from either stainless steel or pho5phor bronze scrpen (%), a protruded metal packing ($e), and a simplified wire screen packing (69). Perfoirnance data of stainless steel Illchlahon packings are also reported (41). Raschig rings were found by Kirschbaum (72) to be just as effective as more complicated ceramic and porcelain shapes. Rotating band columns srem to be more efficient than simple packed columns. The data of Jost (70) indic.tte that small clearances are necessary to obtain efficient operation with this type of column. A 1-mm. wall clearance gave a height of equivalent theoretical plate of 0.9 cm., while a 1- to 2-mm. clearance gave 1.7 cm. Data on siove plate columns arc reported by Nan& and Karim (93). Column esciency may be a function of the system used in testing the column. Storrow and Wilson (fZ,$),however, did not succeed in corrdzting experimental data with a dimensionless equation. The test mixtures used were carbon tetrachloridebenzene and methvlcycloheuane-toluene. Other test mixtures, ethylene dichloiidp-benzene and n-heptane-methylcyrlohexane, are also discussed hy Coulson and Herington (38). Coulson et al. ( 2 7 ) recommend a test mixture containing less than 1% thiophene in benzene for efficiencies up to 65 plates. Two test mixtures for vacuum columns, ( a ) n-dodecanecycloheuylpentane and ( b ) n-triderane-dicyrlohexyl, are recommended by Feldman et al. (40). System ( a ) is nearly ideal, but system ( b ) contains an azeotrope. A nomograph for the test system n-heptane-methylcyclohexane is prescnted by Brooks et al. ($0). The authors' proposal that this be used a i t h other systems should not be followed until the dependence of column efficiency on the system distilled is more fully understood. Liquid flow conditions in a packed tower are Lhown by Grimley (62). A wetted-wall tower and a laboratory tower packed with '/pinch rings were studied. IIcat transfer nntl mass transfer in paclird towers are compared by Tsecker and EIougen (120) and b v McAdams et al (85). Both investigations studied the system air and water L A B O R A T O R Y RISTILLATIONS
The results of several distillation programs were reported. .4mong these are thc analysis of recycle styrene (Glasgow et al., bo!, tho determination of polymer in furfural (Hillyer and Deutschman, 63), and the determination of lithium i n rocks by distillation of lithium chloride from the sintereti sample (Fletcher, 43). All three techniques are suitable for qu~ntitntive analytical work. An unusual technique for the determination of small tlmoirnts of benzene and diethylbenzene in ethylbenzene is desciibvd I-iy Morris el al. (91). A naphtha from Santa Barbara, Venezuela, crude oil was superfractionated and the fractions were analyzed. The results are reported by Schwartz et al. (117). Fractions of 0.5% were collected. The accuracy and precision of light hydrocarbon analysis were studied by the Rubber Reserve Committee on Butadiene Speci-
Vol. 42, No. B
fications and Methods of Analysis. The results are reported by Starr and Lane (1.29). Distillation analyses for propane showed an accuracy of -0.6'%, for butanes +0.4%, and for pentanes +0.2%.
A microstill consisting of an open tube is described by Babcock (6); semimicrostills by Bering ( 1 1 ) and Lappin (77); vacuum stills by Barnitz (Q), Bogdanov (16), Bowen (16), and Moore (90); a flash still by Gold (51); a student still by Mikus (8t9)9 an automatic A.S.T.M. still by Rolfson et al. (110); and equip ment for the distillation of glycerol and fatty acids by Pika (106)
An air sweep distillation unit in which a noncondensable gas (air) is used to carry the vapors from the surface of a boiling liquid is described by Artemov (I). Still heads were also popuIar, and variour designs are deHakala (56),Hopkinr scribed by Diehl and Hart (SO), Doty (X?), (65),Wojciechowski ( I % ' ) , and Ynfiesta and Achon (1366). Reflux dividers, other than in complete still heads, are given b: Nord (94)and Fisher (42). A water trap is shown by Caley and Gordon (21). A Z E O T R O P I C AND EXTRACTIVE D I S T I L L A T I O N
The principles of extractive distillation together with a guidr to the selection of a suitable solvent are discussed by Scheibel (114). In an approximate method of design, this article pointh out that a vapor feed is always desirable in extractive distillstions. Other design calculation techniques are proposed by Norman (96) and by Atkins and Boyer (6). The former assumes constant relative volatility and the latter uses a McCabo. Thiele diagram for the calculation of the trays necessary to make a desired separation. In view of the nonideality of any mixture being handled by these processes, it is surprising that the results of the calculations check the plant data. However, the succrw of the methods is claimed and the plant data presented are interesting. Hodgson ( 6 4 ) stresses the relationship among aseotropic. distillation, extractive distillation, and liquid-liquid extraction The analogy leads to simplified graphical design of azeotropir distillation columns. An extractive distillation column plate efficiency of 48% is reported by Griswold and Morris (65) for the preparation of methylcyclohexane from a straight-fun heptane fraction. The high efficiency is attributed to foam on the trays. Aniline was the solvent. The use of azeotropic distillation to dehydrate ethyl alcohol is reviewed by Norman (95),and to dehydrate allyl alcohol by Hands: and Norman (68). Combinations of extractive distillation and azeotropic distillation into a single process are described by Ahrens (1) and by McICinnis ( 8 7 ) . The latter states that the boiling point of the solvent should be a t least 15' F. above the maximum boiling point of any compound in the mixture being separated and the boiling point of the azeotrope former should be not more than 28' F. below the average boiling point of th? mixture. SPECIAL PROCESSES
Killiamson (134) considers the thermodynamics of isothermal distillation. The results confirm the usual practice. The article describes an improved apparatus designed on theorrtical grounds. The continuous product of dibutyl phthalate in a distillation column was studied by Berman et al. (12). Water was removed as formed in a constant boiling mixture with butanol. Operating variables were catalyst (sulfuric acid) concentration, molar ratio of reactants, and volume of plate holdup. LITERATURE CITED
(1) Ahrens, G. L. (to Standard Oil Development Co.), U. S Patent 2,459,403 (Jan. 18. 1949). (2) Anderson, J A. (to Standard Oil Development Co.), Ib;d.G 2,459,404 (Jan. 18, 1949).
Japuary 1950
x
b
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
(3) Anon., Kelloggram, 1949, No. 2. (4) Artemov, I. S., Dokludy Akad. NaukS.S.S.R., 64, 357 (1949). (5) . , Atkins, G. T.. and Boyer, C. M., Chem. Eng. Progress, 45, 553 (1949). (6) Babcock, M. J., AnaE. Chem., 21, 632 (1949). (7) Bailey, R. V., and Coates, J., PetroEeum Refiner, 27, No. 10, 547 (1948). (8) Bailey, R. V., and Coates, J., Ibid., 28, No. 1, 107; No. 2, 123 (1949). (9) Barnitz, E. S., J.A m . Oil Chemirts’ Sor., 26, 104 (1949). (10) Bergholni, Arne, Svenak. Kem. Tids., 60, 74 (1948). 411) Bering. P..Ibial.. 61. 10 (19491. 412; Berman, S . , Isbenjian,’H., ’Sedoff, A., and Othmer, D. F., IND. ENQ.CHEM.,40,2139 (1948). 113) Bliss, Harding, arid Dodge, B. F., Chem. Eng. Progress, 45, 51, 129 (1949). (14) Bloomherg, Ray, FoodInds., 21,599 (1949). (15) Bogdanov, N. F., Neftyanoe Khoz”,26, 48 (1948). (16) Bowen, J. B., J. Chem. Education, 26, 186 (1949). (17) Bowman, J. R., IND. ENG.CHEM.,41, 2004 (1949). (18) Bowman, J. R., and Ciphelli, M. T., Ibid., 41, 1985 (19) Boyd, D. M., Jr., Petroleum Refiner, 27, No. 10, 595 (1948). (20) Brooks, F. R., Nelsen, F. M., and Zahn, Victor, Ibid., 27, No. 11, 620 (1948). (21) Caley, E. R., and Gordon, Louis, Anal. Chem., 21,749 (1949). (22) Cannon, M. R., IND. ENG.CHEW,41,1953 (1949). (23) Carlson, H. C., and Colburn, A. P., Ibid., 34,581 (1942). (24) Chetrick, M. H., Ibid., 41,430 (1949). (25) Chibaeff, V., Rev. inst.frang. pdtrole, 4, 43 (1949). (26) Chu, J. C., Dmytryszyn, M., Moder, J. J., and Overbeck, R. L., IND. ENG.CHEM.,41, 131 (1949). (27) Coulson, E. A., Hales, J. L., and Herington, E. F. G., Trans. Faraday Soc., 44, 636 (1948). (28) Coulson, E. A., and Herington, E. F. G., Ibid., 44, 629 (1948). (29) Coulter, K. E., Chem. Eng. Progress, 45, 227 (1949). (30) Diehl, J. M., and Hart, Issac, Anal. Chem., 21,530 (1949). (31) Diepen, G. A. M., and Meyer, G., Chem. Weekblad, 44, 57 (1948). 132) Dixon, 0. G., J. SOC.Chem.Ind. (London),68,88 (1949). (33) Doty, W. R., Anal. Chem., 21, G37 (1949). (34) Dreisbach, R. R., IND. ENG.CHEM.,41,1749 (1949)). (35) Dreisbach, R. R., and Spencer, E. S.,Ibid., 41, 1363 (1949). (36) Edmister, W. C., Petroleum Refiner, 27, 609, 659 (1948); 28 No. 1, 128, No. 2, 137, No. 3, 139, No. 4, 157, No. 5, 149, No. 6, 143, No. 8, 128 (1949). (37) Edmister, W. C., and Pollack, D. H., Chem. Eng. Progress, 44, 905 (1948). (38) Eld, A. C., Petroleum Refiner, 27, 537 (1948). (39) Farrington, P. S., and Sage, B. H., IND.ENQ.CHEM.,41, 1734 (1949). (40) Feldman, J., Myles, M., Wender, I., and Orchin, M., Ibid., 41, 1032 (1949). (41) Fisher, A. W., Jr., and Bowen, R. J., Chem. Eng. Progress, 45, 359 (1849). (42) Fisher. H. E., Anal. Chem., 20, 982 (1948). (43) Fletcher, M. H., Ibid., 21, 173 (1949). (44) Fordyce, C. R., and Simonsen, D. R., IND.ENG. CIIEM., 41, 104 (1949). (45) Fowler, R. T., Ind. Chemist, 24, 717, 824 (1948). (46) Frishe, W.C., Chem. Eng., 56, No.7,llS (1949). ENG.CHEM., (47) Gelus, E., Marple, S., Jr., and Miller, M. E., IND. 41, 1757 (1949). (48) Cinnings, D. C., and Corruccini, R. J., Ibid., 40, 1990 (1948). (49) Glanville, J. W., and Sage, B. H., Ibid., 41, 1272 (1949). (50) Claugow, A. R., Jr., Krouskop, N. C., Sedlak, V. A., Willingham, C . B., and Rossini, F. D., Anal. Chem., 21, 688 (1949). (51) Gold, M. K.,Ibid., 21, 636 (1949). (52) Grimley, S. S., Trans. Inat. Chem. Engrs. (London), 23, 228 (1945). (53) Griswold, John, and Buford, C. B., IND.ENG.CHEM.,41, 2347 (1949). (54) Griswold, John, Chu, P. L., and Winsauer, W. O., Ibid., 41, 2352 (1949). (55) Griswold, John, and Morris, J. W., Ibid., 41, 331 (1949). (56) Hakala, R. W., J. Chem. Education, 25,465 (1948). (57) Hall, M. W., and Piret, E. L., IND. ENQ.CHEM.,41,1277 (1949). (58) Hands, C. H. G., and Norman, W. S., Trans. Inst. C h m . Engrs. (London),23, 76 (1945). (59) Hanson, D. N., Fruit Products J . , 28,237 (1949). (60) Hanson, E. S., IND.ENG.CHEM.,41, 96 (1949). (61) Harbert, W. D., Petroleum Refiner, 27, No. 10, 512 (1948). (62) Hibshman, €1. J., IND. ENQ.CHBM.,41, 1366, 1369 (1949). (63) Hillyer, J. C., and Deutschman, A. J., Jr., Anal. Chem., 20, 1146 (1948). (64) TTodgson, M. A. E., Research (London),1,568 (1948). r
35
(65) Hopkins, R. L., Petroleum Processing, 4, 698 (1949). (66) Horsley, L. H., Anal. Chem., 21, 831 (1949); 19, 508 (1947). (67) Hyman, D., and Kay, W. B., IND.ENG.CHEM.,41, 1764 (1949). (68) Jasper, J. J., and Pohrt, H . F., J . Chem. Education, 26, 485 (1949). (69) John, H. J., and Rehberg, C. E., IND.ENG.CHEM.,41, 1056 (1949). (70) Joet, W., Angew. Chem., B20, 231 (1948). (71) Kemp, H. S., and Pyle, Cyrus, Chem. Eng. Progress, 45, 435 (1949). (72) Kirschbaum, Emil, Angew. Chem., B20, 197 (1948). (73) I b X , B20, 333 (1948). (74) Kirschbaum, Emil, Chemie-Ing.-Tech.,21, 61 (1949). (75) Kobe, K. A., and Long, E. G., Petroleum Refiner, 28, No. 1, 83, No. 2, 113, No. 3,125, No. 4, 161, No. 7, 145 (1948). (76) Lamb, G. G., and O’Brien, L. J., IND.ENG. CHEM.,41, 182 (1949). (77) Lappin, G. R., J. Chem. Education, 25, 657 (1948). , Acad. roy. Belg., C ~ U S Ssei., ~ Mem., 23, 3 (78) Ann. chim. (12), 2, 158 (1947). Ann. 8oc. sci. Brwelles, Ser. I, 60, 155, 163, 169,228 (1946) ; 61, 153,255 (1947) : 62, 55, 93, 128 ( I 948) : 63, 58 (1949). (81) Lecat, Maurice, Bull. classe sci., Acad. Toy. Relg., 29, 273
(79)
(80)
(1943) ; 32, 351 (1946). (82) Lecat, Maurice, Compt. rend., 223, 286 (1946). (83) Li, Y.M., and Coull, J., J.Inst. Petroleum, 34, 692 (1948). (84) Littmann, E. R., and Klotz, J. R., IND. ENG. CHEM.,41, 1462 (1949). (85) McAdams, W. H., Pohlenz. J. B., and St. John, R. C., Chem Eng. Progress, 45, 241 (1949). (86) McCarty, L. V., J. Am. Chem. Soc., 71, 1339 (1949). (87) McKinnis, A. C. (to Union Oil Co. of Calif.), U. S. Patent 2,461,993 (Fob. 15, 1949). (88) Marschner, R. F., and Cropper, W. P., IND.ENG.CHEM.,41, 1357 (1949). (89) Mikus, F. F., J. Chem, Education, 26,230 (1949). (90) Moore, R. G. D., Chemist-Analyst, 37, 66 (1948). (91) Morris, H. E., Lane, W. E., and Stiles, R. B., Anal. Chem., 21, 998 (1949). (92) Murdoch, P. G., Chem. Eng. Progress, 44,855 (1948). (93) Nandi, 5. K., and Karim, B., J. Indian Chem. Soc., Ind. and News Ed., 11, 3 (1948). (94) Nord, Melvin, Chem. Eng., 55, No. 11, 154 (1948). (95) Norman, W. S.,Trans. Inat. Chem. Engrs. (London), 23, 66 (1945). (96) Ibid., p. 89 (1945). ENG.CHEM.,40,2185 (1948). (97) Obert, E. F., IND. (98) Okamoto, K. K., and Van Winkle, M., Petroleum Refiner, 28, No. 8.113 (1949). (99) Olds, R. H., Reamer, H. H., Sage, B. H., and Lacey, W. N., IND.ENQ.CHEM..41.475 (1949). (100) Organick, E. I., and Studhalter, .W. R., Chem. Eng. Progress, 44,847 (1948). (101) Ortuno, A. V., Ion, 9, 10 (1949). (102) Othmer, D. F., and Gilmont, Roger, IND.ENG. CHEM.,40, 2118 (1948). (103) Othmer, D. F., Savittp 8. A., Krasner, A., Goldberg, A. M., and Markowitz, D., Ibid., 41,672 (1949). (104) Peters, H. F., Petroleum Refiner, 28, No. 5, 109 (1949). (105) Pika, L., Soap, Perfumery and Cosmetics, 21, 1117 (1948) (106) Poettmann, F. H., and Mayland, B. J., Petroleum Refinsr, 28, No. 7,101 (1949). (107) Prenfle, H. W., Jr., Greenhaus, L. R., and York, R., Jr., Chem. Eng. Progress, 44, 863 (1948). (108) Reamer, H. H., Sage, B. H., and Lacey, W. N., IND.ENQ. CREM.,41,482 (1949). (109) Rector, N. K., Petroleum Processing, 4,525 (1949). (110) Rolfson, F. B., Penther, C. J., and Pompeo, D. J., Anal. Chem., 20, 1014 (1948). (111) Rose, Arthur, Ibid., 21, 81 (1949). (112) Rush, W. F., and Gamson, B. W., IND.ENG.CHEM.,41, 78 (1949). (113) Sanderson, R. T., Ibid., 41, 368 375 (1949). (114) Scheibel, E. G., Chem. Eng. Progress, 44,927 (1948). (115) Scheibel, E. G., IND.ENG.CHEM.,41, 1076 (1949). (126) Schlinger, W. G., and Sage, B. H., Ibid., 41, 1779 (1949). (117) Schwartz, F. G., Gooding, R. M., and Eccleston, B. H., Ibid., 40, 2166 (1948). (118) Sherwin, D. S., Chem. Eng. Progreas, 45, 342 (1949). (119) Smith, R. B., and Dresser, T., Ibid., 44,789 (1949). (120) Souders, M., Jr., Matthews, C. S., and Hurd, C. O., IND. ENG.CHEM., 41, 1037 (1949). (121) Spencer, H. M., Ibid., 40, 2152 (1948). (122) Starr, C. E., and Lane, T., Anal. Chem., 21, 572 (1949). ~
36
I N D U S T R I A L A N D E N G I N E E R I N G CHEMIS’TRY
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Oi:tl)kif?r
18, 15144
ARTHUR D. Lirri-E, INC., CAMBRIDGE, MASS.
iX THE fall of 1947 the first High Vacuum Symposiurii (Y4) was held in Cambridge, Mass., to celebrate the accoml.dishments of high vacuum in World War I1 and to usher in a I I C K era of high vaci~umtechnology. That same year-end niarlced the last appearance of this review ( 9 9 ) ; in 1948 there was imufficient niaterial to command space. The paradox is sinipie: the symposium had celebrated the conclusion of pEn era and only in a remote and confused sense did it presage the birth of another. The era had reached its olimax il-ith the production of giant vacuum equipment (44,58) for the inagaetic and other separation processed for uranium (46),the produotion of magnesium, and the dehydration of biologicals and wartime foods; but the foundat,ions had been laid in the previous 15 years in electroiiics 2nd conimercial molecular distillation. After the Cambridge conference there hm been a pause for review and planning of new work. The iiitervening lull in inveiit>ionand publication should not be mistaken for inact,ivity. Greater volumes of materials are being procemod on molecular stills thnn ever before, and many new researetics w e knuwn t,o be in the embryonic stage. The low temperature distillation of water from fruit juices (48, 4 9 ) has reached gigantic proportions. The definition of whast is distillation and what is high vacuum has become broadened (S8), and it s e e n s necessary to introduce a new term. The author offers with appropriate misgivings, I h c wurd “niegavacuuni” to describe t,he transport uE large niaesw of gases a t pressures far below those previously avnilabie in heavy industry, hut, yet not approcching the submicron range of accepted high vacuum. To use current clichds, the latter handle vast volumes of “nothing,” the former, very considerable masses of “something.” One requiros a vacuum pump, the other a vamum engine or prime mover. Steam eject0rs’an.d high pressure oil vapor ejectors, both in multiple stage ( 3 Q ) ,have become available as prime movers. Besides the application to orange juice (@), megavacuums are being introduced with increasing success for the drying of coffee sirup (td), the melting of metals in the absence of sir (65),and reductive me”:allurgy (68) in general. If the va,cuum requirements of this new era are to be envisaged, it is only necessary t o note t8he giant nuclear fissicn mschines tJhat are being projected and the laments of the high v-acuim distillers (28). A11 require larger, quic’ker, higher, and cheaper vacuums. The most significant recent contribut,ions have been in the form of symposia, review, and boolts. Two important conferences on high vacuum have been held, one a t Glenea,gles, Scotland (10,1.9, 18, %9,43, 46, ,5J, 5 6 ) , under the auspices of t,hr
(13rit’ish)Society of Chemical Industry, and theother in Caslbriclgc(34.). A full report (1,14,19,SS,S6,56,38,42,44,48,60,61, &+; 5 7 ) of ihe latter meeting has been available to readers of this journal since May, 1948. Some of the contributors presented, substantially similar papers ( 1 , 19) at both meetings, but, the stress v a s on technique (S6), measurement (14, 48), and megavacuums a t the American event and on high vacuum processes a t the British gathering. Notable communications ai; Ihm. bridge were the description of wax-born methods of loak detec lion and of measuring pressures from 10 mm. downward. The Gleneagles meeting opened with a broad survey by C ) i i 4 man (18) of the theory underlying vacuum technique. S w a l l o ~ and Gourlay (56) surveyed vacuum evaporation for the metalization of surfmes arid the purification of high polymers and na,turnl oils from low molecular weight contaminants. Morse (@) described American equipment in the megavacuum range for orange juice and biologicals, and Stauffer (JS), also from National Research Corporation, described the reduction and distilla tion of magnesium and calcium. ‘4paper of some interest for thie review was Fawcett’s appraisal of molecular distillation ( 2 3 ) As a leader of .the British school in the early days, %an-cet,t’s opinion, as follov;~ (condensed), after some years of scpa,la t inii has both debcbment and matnrity: Iloleculsr distillaticxi i h R process for the rather special case :tiid is not likely, in the present, form, tlo become a generally applied proc,ess on the commercial scale. One such special case is vitamin .4., where favorable factors have led to success. The iiwelopment. of cheap and effective molecular fractiona,ting columns of 10 to 20 molecula~plates would make the process of much more general applicability and value t o the Fheniicai engineer. To achieve this, a radical redesign of existing titi118 appears necessary.
It will be interesting to observe whether the challenge facing the moIecnl.ar still will. be met during the next few years. That it,s proponents have not lost faith is evidenced by other excellent reviews (11, 46), profusely illustrated. The very recent appraisal by Jaeckel and Oetjen (37) from. the Leybold laboratory, commands attention. Even more commanding, and indced, perhaps the most important event. in the period under review is the publication of Dushman’s long-awaited book ( 2 0 ) . Uniqut?; t~ll-inclusive, and accurat,e, i t will nevertheless irk the practical reader by its intellectual nutidiness and lack of selectivity. It? influence will be profound. Minor moclib’cations have appeared in the laboratory art, The falling-film still, which viould have seemed to defy further variation, has been altered (5)) to accommodate samples of I to 5 grams. Evaporation is done from the inside of a hot glaszi tnbr
