{"http:\/\/dx.doi.org\/10.14288\/1.0062193":{"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool":[{"value":"Science, Faculty of","type":"literal","lang":"en"},{"value":"Chemistry, Department of","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider":[{"value":"DSpace","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#degreeCampus":[{"value":"UBCV","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/creator":[{"value":"Guthrie, John","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/issued":[{"value":"2011-11-07T21:01:28Z","type":"literal","lang":"en"},{"value":"1940","type":"literal","lang":"en"}],"http:\/\/vivoweb.org\/ontology\/core#relatedDegree":[{"value":"Master of Arts - MA","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#degreeGrantor":[{"value":"University of British Columbia","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/description":[{"value":"[No abstract submitted]","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO":[{"value":"https:\/\/circle.library.ubc.ca\/rest\/handle\/2429\/38813?expand=metadata","type":"literal","lang":"en"}],"http:\/\/www.w3.org\/2009\/08\/skos-reference\/skos.html#note":[{"value":"DISTILLATION OP AZEOTROPIC MIXTURES By John Guthrie A Thesis submitted i n p a r t i a l fulfilment of the requirements for the degree of Master of Arts The University of B r i t i s h Columbia October - 1940 D i s t i l l a t i o n of Azeotrppic Mixtures The capacity of a column i s defined (1) as a measure of the amount of l i q u i d and vapor which can pass counter-current to each other i n the column, without causing flooding\u201e\u2022 Walker, Lewis, McAdams and G i l l i -land (2) have stated that flooding i s caused by f r i c t i o n of the r i s i n g gas holding up the liquid*, Souders and Huntington (5), i n work on a hubble-cap column, l i s t e d the following ways of overtaxing a column; by flooding or too much l i q u i d down Mie wiersj priming, or too great a pressure d i f f e r e n t i a l over the l i q u i d head? entrain-ment resulting from too great a vapor velocity\u00a9 However, these seem to be three ways of saying the same thing since a high v e l o c i t y (which produces entrainment) also produces more reflux or more l i q u i d down the wiers<> In work carried out by Weiss and Elgin (4) i t was found that at low gas rates, water gradually became the continuous phase ( as volume of water down the column increased ), and flooding resulted. At higher gas rates flooding appeared as a result of entrainment e In most d i s t i l l a t i o n however, the reflux i s less then, or at the greatest ( i n f i n i t e reflux r a t i o ) equal to the vapor mass r i s i n g , so that increase i n vapor v e l o c i t y w i l l bfe the chief factor i n causing flooding* I t was also shown that at certain v e l o c i t i e s the hold-up i n the packing sudden-2 l y increased very rapidly and could be used as an i n d i - ? cation of flood point\u2022 Others (12) have mentioned the importance of hold-up, a low hold-up leading to a sharp cut.*, I t has also been found (4,5) that a dry packing gave quite different results from a wet packings EFFICIENCY The efficiency of a column i s , i n general, the change of composition from one plate to another with per-fect equilibrium between l i q u i d and vapor, as compared to the equilibrium that i s actually attained. As v e l o c i t y r i s e s , the efficiency goes to a maximum and then f a l l s off (16) when excess entrainment shows up, Rhodes (7) showed that plate efficiency was largely independent of reflux but that entrainment was not\u2022 Holbrook and Baker (8) also state bhat entrainment i s greatly affected by vapor v e l o c i t y . There i s however, a certain r e l a t i o n between the two since a large reflux (with high vapor velocity) leads to entrainment and lowered ef f i c i e n c y * This i s not necessarily always the case. Sherwood and Jenny (18) have stated that even 10 % entrainment does not seriously affect e f f i c i e n c y . This i s also mentioned by Colburn (19) e PACKING The packing used i n the present investigation was No. 18 Jack chain. This packing i n comparison with such as beads , rings, helices etc\u00ab, gives a high ef f i c i e n c y 3 with a large capacity,, Packings have been investigated by a number of workers. H i l l and Ferris (10) and Marshall, Walker and Baker (9) showed that the chain mentioned above was highly e f f i c i e n t . Penske, Quiggle and Tongberg (11) have shown the d e s i r a b i l i t y of using packed columns. These give high e f f i c i e n c y , large throughput and a low hold-up. pa pel\" In a l a t e r (12) they stated that helices were found to be B best. This was also mentioned by Rose (13) and Tongberg, Lauroski and Penske (SO\u00ae A packing developed by Stedman (15) was a conical wire gauze which gave as high as twenty theoretical plates per foot with a high capacity, Peters (20) has stated that the efficiency of a column was a function of the radius of the packing. This has also been mentioned by Carswell (21) \u2022 PRESENT INVESTIGATION The present work i s an attempt to apply certain physical characteristics of the mixtures to the capacity ofna column. Souders and Brown (6) state that entrainment which l i m i t s : capacity i s a function of the v e l o c i t y , density of l i q u i d and vapor, and that surface tension has i t s e ffect. The l a t t e r affects the size of the entrained p a r t i c l e s . Holbrook (8) however, states that the absolute surface tension cannot be correlated to the entrainment, and agreement i n this i s reached by Rumford (32)\u2022 Ashraf, Cubbage and Huntington (27) state however that density and surface tension are connected to the entrainment (or that which l i m i t s capacity). In 1924 the problem was approached TABLE 1 No, Mixture A B B.P, B C. Densities A B Mol % A Mol % B 1. Et-Ale 78*15 .789 .998 89 .43 10,57 2. n Prop II 87.72 e804 .998 43.17 56 .83 Ale 3. Et Ac ti 70.4 \u2022901 .998 \u2022\u2022'76vG0 24.00 Io Me Ale Garb 55.7 .796 1.595 5.5,5 44.5 Tet. 5. \u2022 Et Ale II 64.95 .789 1.595 38*7 61*3 6. Et Ac II 74.75 .901 1.595 57.0 43.0 8. Et Ale 42.4 .789 18'260 14.0 86.0 9 0 Acet II 39.25 ..792 1.260 39.-0 61.0 10, , Me Ac it 40.15 .927 1.260 : 30.5 69.5 ; 11. Acet Me 55 e9 .792. .796 80 ..0 20.0 Ale 13. : Et Ac II 62 \u00ab3 \u2022 901 '\u2022*796 t 8.3 91.7 14 . C6 H6 n 58,34 \u201e894 .796 38 06 61.4 4 i n a different way by Lewis and Whitman (22) who studied the liquid-gas surfaces from the point of view of ab-sorption using absorption c o e f f i c i e n t s . They believed that the major factor i n determining f i l m thickness (which i s a measure of absorption or r e c t i f i c a t i o n ) i s the r a t i o r of v i s c o s i t y to density. Sherwood, Shipley and Holloway (28) have made an attempt to correlate surface area of packing and densities of l i q u i d and vapor to column v e l o c i -t i e s and did derive a relati o n for these 0 Brewer (29) showed that the capacity of a column was largely depen-dent on the molecular vo lume of the l i q u i d used c In general i t may be said that certain properties of the l i q -quids, such as v i s c o s i t i e s , density and mol\u00ab volume may be correlated with column capacity but correlation of surface tension seems doubtful. Much of the previous work i n t h i s f i e l d has been carried out using single component liquids and, very often, gases such as a i r , carbon dioxide etc\u00ae, have been used as of tn \/* tvrcs the vapor phase. In the present investigation a series were used. These were azebtropes. Such mixtures allow a study of physical characteristics to be made while no change i n composition occurs. APPARATUS A two- l i t r e ring-necked fl a s k (Pig. 1) covered with a layer of 85% magnesia ins u l a t i o n , was used to hold the mixtures. Heating was carried out by a bare nichrome wire immersed i n the l i q u i d . When necessary, the reflux FIGURE 2 5 could be returned to the f l a s k by the side arm. The coltmn was a glass tube 108 cm. long, 2.5 cm. inside diameter. It was nearly f i l l e d with No, 18 Jack chain and lagged with four layers of l \/ l 6 inch asbestos sheeting. Around th i s was wound a nichrome wire resistance, the number of turns pe r unit length increasing at the top to allow for a temperature gradient\u2022 This c o i l was heated by A.C. governed by a variac. A l l this was covered by one and one quarter inches pf 85% magnesia lagging. At the top was placed a system of condens ers. EXPERIMENTAL DETAILS The apparatus was f i r s t run at f u l l reflux and flood-ed. This was i n order to wet the packing thoroughly. The current was now shut off to allow the l i q u i d to return to the f l a s k . Then power was increased u n t i l the column was on the point of flooding. The reflux was then returned v i a the side arm and power into the column heating c o i l gradually increased u n t i l no condensation occurred on the inside walls of the tube. This could be seen by observing the uncovered bottom of the column. Then the stop-cock to the side arm was closed and the column brought to f l o o d . The side con-denser D was now connected at S and the output of l i q u i d per second by volume measured i n the graduate G. This volume was converted to grams per second. By applying the weight i n grams of one mol. of mixture, and the gas laws, the volume of vapor per second up the column was calculated. TABLE 55 If\u00a9.. Wt. A Wt. B : Vol. A Vol, B. Volumes A used B 1. 4118 190 5219 190,4 1200 44 \u20222.;. 2593 1023 3225 1025 960 310 3. 6692 432 7428 433 1200 70 4\u201e 1777 6845 2233 4292 450 865 5. 1782 9430 2259 5900 500 961 . 6\u00ab 5019 6614 5571 4147 750 558 8. 644 6546 817 5195 200 1272 9. 2264 4643 ,, 2858 3685 619 : 799 ''10.' 2257 5290 2435 4200 500 863 11. 4644 640 5864 805 1100 144 13 s 731 2937 811 3690 \" 266 L212 14. 3012 1966 3370 : 2470 750 551 6 This i n turn, was converted to cm. per second using the area of the column. RESULTS . Table 1 l i s t s the mixtures used, composition by mol, percent, b o i l i n g points and densities. Table 2 shows the weight of each component i n 100 mol. of mixture, volume composition of 100 mols., and actual volumes of each component used. Table 3 gives the time for 10 cc, of d i s t i l l a t e to run into the side arm graduate, density of this mixture, weight vaporized per second, weight of one mol. of mixture and volume of l i q u i d vaporized per second. These l a s t figures were found by converting one mol. of mixture to vapor volume at the given temperature and then calcula-t i n g the volume occupied by the weight i n column 4. Table 4 gives the v e l o c i t y , reciprocal mol. volume of the mixture used, density at B.P., v i s c o s i t y at B.P., and ra t i o of v i s c o s i t y to density! i n the case of four of the mixtures), The v i s c o s i t i e s were found as follows: small amounts of ,v each mixture used were d i s t i l l e d over and used i n a Wash-burn Viscosimeter. Readings were made at a series of tem-peratures . These were then plotted and extrapolated to B.P. These values were compared with calculated values using (31) In n = x, In n, + x^ln nowhere, n = v i s c o s i t y of mixture n, , n^are v i s c o s i t i e s of components x, and x a are mol, fractions of components. These values may be seen i n Table 4, TABLE 3 No-V Time\/lOcc \u2022(sec.\") Density (g\/cc) Wt\/Sec Wt 1 mol mixture Vol\/sec (vapor) \/\u2022I.:- 12.5 ,796 ,637 43,06 427 : \u2022 * 14.7. ;\"\u2022' \u00ab850 *578 36e06 475 12,7 .900 ,709 71,20 280 , '4. \u2022 11.4 1*321 1,160 86.90 391 5> \u2022 .. '11.5' 1.874 ;1.195 ... 111,88 297 6. \u2022ib-,5 1.200 :1.133 116,38 278 . 14,6 1.196 ' .819 71.80 295 11.7 1.055 ,900 . 65,98 \u2022'-349 \u2022 MG. 11.6 1.138 *98Q 75s38 329 1.1. 11.6 *790 ,671' 53,00 340 13 \u00bb 14.1 ,815 ,578 36,48 436 14 , 12,0 ,852 .71 49,94 387\". Figure 2 shows a plot of reciprocal mol, volume agcdinSfe vapor velocityo The result i s not very satisfactory but i t i s similar i n nature to that of previous work (29). Figure 3 i s a plot of vapor velo c i t y against n c\/p p where f\u00bbL i s the l i q u i d density and T>lis the l i q u i d v i s c o s i t y , both at B. P. It was previously staged (22) that the major factor i n determining f i l m thickness i s the ra t i o of l i q u i d v i s c o s i t y to density. In turn, this r a t i o i s a measure of the rate of r e c t i f i c a t i o n . Furnas and Taylor (33), i n a study of a l - . cohol mixtures using a variety of packings, based t h e i r work on absorption and found that major resistance to transfer i s i n the l i q u i d f i l m . In Table 5 % the figures for numbers 3, 5, and 6 were found l a t e r and the resulting viscosity-density ratios used i n the graph ( f i g . 3) to f i n d the v e l o c i t i e s . In Table 6 are then l i s t e d these v e l o c i t i e s , the actual experimental v e l o c i t i e s , and the percent error. Results are fair\u00ae It i s evident that when these ratios are applied to F i g . 3 the resulti n g graph w i l l not be quite as shown there. SUMMARY'-It has been found that with binary mixtures, as with single component l i q u i d s , the mol. volume could be a factor i n determining capacity of a column. It was also shown that the r a t i o of l i q u i d v i s c o s i t y to l i q u i d density could i n a general way be connected to the capacity. This r a t i o seems to have some theoretical importance since other investigators (22, 33) have mentioned the part TABLE 4 Ncu Vel\/sec l\/mol v o l . 2. 97 ,0236 ,806 ,438 13. 89 \u2022 0223 - . - . -1. 88 . 0185 .746 .330 .456 4 e 80 ,0152 1.290 ,550 .43 79 .0143 -, 9 \u00a9 ,0160 - -XX\u00ab 7P ,0150 - -10, 67 ,0146 -, 6 i .0123 - - . \u2022 - \u2022 8\u00ab 60 \u2022 ,0166 1\u00abxvx ,338 .288 3 . 57 ,0127 -6 \u2022 56 ,0104 - -TABLE 5 Wo. n ^ ( experimental) n L( calculated) 1. ,230 .490 2 \u00ab\u00a9 .438 .423 3\u00ab ~ .295 .304 4, o470 5 \u00a9 .543 .342 6\u00ab .371 ,374 8, ,338 .295 ' 8 that films play i n absorption, In Tafcle 6 i t w i l l be noted that run No. 5 i s mstet i n error. Prom Table 5 i t can be seen that the calcu-lated and experimental values of v i s c o s i t y are quite different\u201e It ms quite possible that the experimental value here may be i n error since a good deal of d i f f i -culty was experienced i n working with this mixture. There was a tendency for the product to vary a certain amount i n density. Bearing t h i s i n mind and assuming that the calculated values are f a i r l y correct, the v i s c o s i t y would then have a lower value, This would considerably decrease the error as shown i n Table 6, It i s evident, however, that the above factors are not s u f f i c i e n t to gifee a clear indication of what occurs i n a fractionnating column, A more complete work would have to include a study of pressure firop, hold-up e t c , which have been shown to have some effect on capacity. TABLE 6 No\u00a9 PL n L Calc, V e l . JBctual Vel. Error 3 \u202285 e 29 \u00ab339 67 -57 17.5$ 5 ,52 \u2022406 76 61 24*6 6 X \u00abxx \u202236 ,323 64 56 14.3 A CKN OWLEBGEMEN T S Thanks'are extended to Dr. M.J. Marshall under whose direction the investigation was oarrfeed ECU for h e l p f u l suggestions and advice\u00bb 10 \" ' REFERENCES l s Peters, W.A., J , Ind. Eng. Chera., 14, 426 (1922) e 2. McAdama, Lewis, Walker and G i l l i i a n d , \" P r i n c i p l e s of Chemical Engineering; 3rd Ed., New York, McGraw-Hill, 1939\u00a9 3. BSouders, M., J . Ind. Eng. Chem., 30, 86, (1938)\u00ae 4. E l g i n , J.C, Weiss, F. B., i b i d , 31, 435 (1939). 5. Fenske, M.R., Lauroski, S *. Tongberg, CO., i b i d , 29, 957 (1937). 6. Souders, M., Brown, G.G., i b i d , 26, 98 (1934). 7. Rhodes, F.H., i b i d , 29, 51 (1937 )\u201e 8 0 Holbrook, G.E., Baker, E.M., i b i d , 26, 1063 (1934), 9. Marshall, M.J., Walker, F., Baker, D.H., Can. J . Research, B15, (1937). 10 9 H i l l , J.B.\u201e F e r r i s , L.W., Ind* Eng. Chem., 19, 379 (1927)* 11. Fenske, M.R,, Quiggle, D\u00ab, Tongberg, CO., i b i d , 24, 408 (1932). 12. Fenske, M.R., i b i d , 26, 1169 (1934). 13. Rose, A., i b i d , 28, 1210 (1936)* 15. Stedman, D.F., Can. J . of Research, 15B, 383 (1937)\u00a9 16. Peavey, C.C., Baker, E.M, , ^iJlndSSEnggSchem^^? }, 29, 1056 (1937). 18. Sherwood, T.K., Jenny, F.J., i b i d , 27, 265 (1935). 19o Colfeurn, A.P., i b i d , 28, 526 (1936)\u201e 20. Peters, W.A., i b i d , 14, 476 (1922), 21. Carswell, T.S., i b i d , 18, 294 (1926), 22. Lewis, W.K., Whitman, W.G., i b i d , 16, 1215 (1924). 23. Murphree, E.V., i b i d , 17, 747 (1925). 2!7\u00ab Ashraf, F.A., Cubbage, T.L.. Huntington, R.L., i b i d , 26, 1068 (1934). 28. Sherwood, T.K., Shipley, G.H., Holloway, F.A.L., i b i d . 30, 765 (1938). 29. Brewer, CP., Thesis, Dept. of Chem., University <f B r i t i s h Columbia,(1938). 31. M i l l a r d , E.B., \"Physical Chemistry for Colleges\", 4th Ed., McGraw-Hill, (1936). REFERENCES (continued) 92e Rumford, F. , J\u00ab Roy, Teeho Colls,, (Glasgow) 4, 650 (1940), \u202233. Furnas s C.C., Taylor, M.L., Trans<\u2022> Amer, Inst\u00ab Chem. 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