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INDUSTRIAL AND ENGINEERING CHEMISTRY
Literature Cited (1) Claassen, Z . deut. Zuclcerind. Ver.. 29, 1161 (1904); 39, 807 (1914); A&. Suikerind., 23, 303 (1915). (2) Claassen, Z . deut. Zuckerind. Ver., 41,809, 825 (1916). (3) Curin, Oe, Ihid., 19, 756 (1894). (4) Duhring, “Neue Grundgesitze der rationeller Physik und Chemie”, Leipsig, 1878. ( 5 ) Holven, ISD. ENG. CHEM., 28, 452 (1936). (6) Holven, U. S. Patents 3,135,511-12 (1939), 2,263,847 (1941); Cuban P a t e n t 11,617 (1940). (7) International Critical Tables, Vol. IT, p. 344, New York, McGram-Hill Book Co., 1927. ( 8 ) Ibid., Vol. 111,pp. 211-12. (9) Ibid., Vol. 111,p. 328. (10) Kahlenberg, J . P h ~ s Chem., . 5, 339 ( l g o l ) .
Voi. 34, No. 10
(11) Kukharenko, “Vistnik Cukrovoi Promislorosti”, Kiev, 1920; Intern. Sugar J . , 29, 649 (1927). (12) Langen, German P a t e n t 210,543 (1909). (13) Monrad, IND. ENQ.CHEhf,, 21, 139 (1929). (14) Prinsen Geerligs, “Cane Sugar and I t s Manufacture”, p. 6,London, Norman Rodger, 1909. (15) Thieme, Facts About Sugar, 22, 1156, 1208-12 (1927); “Studiea in Sugar Boiling”, tr. by 0. &I. Willcox, New York, Facts About Sugar, 1928. (16) Tressler, Zimmerman, and Willits, J . phys. Chem., 45, 1242 (1941). (17) Webre, IND. Eria. CHEM., 27, 1157 (1935). (18) Wenner, Bur. Standards, Sci. Paper 531 (1926). (19) White, I N D . ENG. CHEhf., 22, 230 (1930). PRESENTED before the Division of Sugar Chemistry and Technology a t the 10.7rd Meeting of the AMERICAN CHEMICAL SOCIETY,Memphis. Tenn.
Densities of Liquefied Petroleum Gases TECHNICAL COMMITTEE, NATURAL GASOLINE ASSOCIATION OF AMERICA Kennedy Building, Tulsa, Okla.
HIS work was d e signed to provide newly determined liquid densities over a relatively wide temperature range for propane, p r o p y l e n e , isobutane, n-butane, 1-butene, and n-pentane which would be useful in the establishment of more accurate densities for them. A literature survey of the liquid densities of these liydrocarf ons had d i s c l o s e d that many density data mere for single temper‘‘Lt ures or for short temperature ranges. I n addition, few citations were found for t e m p e r a t u r es above 68” F. With the exception of n-pentane, the density values were in rather poor agreement. Only one literature reference was a v a i l a b l e indicating the degree to which hydrocarbon mixtures follow the loss of perfect solutions. It WRS decided, therefore, to include in the work the measurement of densities of two different two-component mixtures for a short temperature range.
T
F IC I RE 1. METALPYCNONETER USEDIN EXPERIMENTS
Hydrocarbons Investigated Fractionation of natural gasoline yielded a number of concentrates; each contained approximately 95 per cent of the desired paraffins. Each concentrate mas then fractionated in a column having 20 feet of S/8-inch stone Raschig rings as packing. A cut was taken from the middle of the temperature plateau of each concentrate for the density measurements. Each cut was examined for purity by a special precision weathering test: a weathering range of less than0.5” F. between the 20 and 70 per cent vaporized points was found for all cuts, which indicated a purity of a t least 99.5 per cent. The purity of the propane, however, was 99.8 per cent. Propylene was obtained by the fractionation of vapors from a cracking furnace. A heart cut from the propylene temperature plateau was taken for the density measurements. 1-Butene was prepared by the dehydration of n-butyl alcohol, followed by fractionation of the products of dehydration. Fractionation of both of these olefins was carried out in the column used in preparing the paraffins. The olefins were tested by [ow-temperature fractional analysis and Orsat analysis, and a purity of at least 90.5 per cent was found. Two mixtures were made by blending the pure components; the mole per cent compositions were determined by lowtemperature fractional analysis: Mole % ’ hlixt. 1 Mixt. 2
Propane Isobutane n-Butane n-Pentane
Mole %
52.6
47.4 62.4 47.6
Equipment and Procedure For temperatures above 0” F. a metal pycnometer was used for density mcavurement (Figure 1). It consisted of a steel cell, A , of approximately 4500 ml. capacity, to the top of which was attached a smaller steel cell, B, of approximately 400 ml. capacity. The two cells were connected by valve C. A smaller valve, D,was connected into the unattached end of the smaller cell. The empty weight of the complete
October, 1942
INDUSTRIAL AND ENGINEERING CHEMISTRY
The liquid densities for propane, isobutane, n-butane, and n-pentane have been determined for the temperature range -50" to 140' F., and for propylene and 1-butene from 0' to 60" F. The densities of approximately equimolar mixtures of propane-isobutane, and n-butane-n-pentane have been measured from 20' to 100" F. These new densities for propane and n-pentane and values found in the literature agree, in general, very well. Values for isobutane and n-butane in
unit was about 12 pounds. The volume of the larger cell was calibrated with water for both temperature and pressure. For temperatures below 0" F. a glass pipet was used to measure density (Figure 2). The pipet consisted of a spherical bulb of approximately 50 ml. capacity, to which was attached a stem calibrated in intervals of 0.01 ml. and having a total volume of approximately 2.5 ml. All temperatures above -36" F. were measured by a mercury-in-glass thermometer which had been calibrated against a National Bureau of Standards certified mercury-in-glass thermometer. For temperatures below -36" F. a five-junction copper-constantan thermocouple was used which had been calibrated against the same certified thermometer. The calibration curve was extrapolated to cover the temperature range from -36" to -50" F. A torsion balance having a sensitivity of 0.2 gram was used to weigh the pycnometer. It was checked for equality of length of the balance arms. The weights used were calibrated against analytical quality weights. No correction for buoyancy was found necessary. MEASUREMENTS ABOVE 0' F. The metal pycnometer was first pumped down to an absolute pressure of less than 1mm. mercury. Sufficient hydrocarbon was flowed into cell A to fill it, together with enough to fill half the smaller cell, B. Valve D was closed and valve C left open. The unit was placed in a constant-temperature bath in such a manner that cell A was totally immersed in the bath liquid but with no part of cell B immersed. When necessary, heat was applied externally to cell B to keep its temperature from 10" to 15" F. higher than the bath temperature. The length of time required to bring the temperature of the cell iind hydrocarbon content to the bath temperature was found experimentally. The practice was to leave the unit in the bath for a time 50 per cent longer than was found necessary. The bath temperature was held to *0.1" F. Just before the unit was removed from the bath, valve C was closed. After removal, the outside surface of the unit was dried, cell B evacuated, and if the bath temperature was sbove the dew point temperature of the room air, the unit wa8 then weighed. When the bath temperature was below the dew point of the room air, however, an additional step was necessary to prepare the unit for weighing which would prevent the condensation of moisture on the outside of the unit. Aftor cell B was evacuated, valve C was opened immediately and heat applied to the unit to bring its temperature above the dew point of the room. Cell B served to take up the expansion of the liquid hydrocarbon during this heating and thus avoided the creation of a high hydrostatic pressure in cell A with its accompanying damage to the unit. MEASUREMENTS BELOW 0" F. Densities were measured by an indirect method in the glass pipet. The pipet was first evacuated, filled with enough of the hydrocarbon so that at a temperature around 0" F. the meniscus would be near the
1241
the literature are in marked disagreement among themselves and with the figures reported here. When compared with the other publshied values, the new densities are somewhat lower for isobutane and somewhat higher for n-butane. The agreement of this work with previously published densities for 1-butene is good. Considerable difference was found for propylene. The two mixtures investigated do not appear to deviate appreciably from perfect solutions.
top of the graduated stem, and then capped. At or slightly above 0" F. the volume of the hydrocarbon was noted. The bath temperature was then lowered in steps of 10" to 20" F. At each temperature the bath was held to 1 0 . 1 " F. until the meniscus showed no change in level in 4 minutes. The volume was noted. Because the calibration of the pipet was carried out at room temperature, the observed volumes were corrected for the change in thq calibration of the pipet due to the low temperatures of the measurements. The density was calculated b i the following formula:
_ vrJdo - dg ut
where00
=
vt
=
corrected volume of hydro c arbon in pipet at 0' F. corrected volllmi? of hydrocarbon
in
pipet at t o F. do = d e n s i t y of hydrocarhon at 0'
dt
=
F. density a t t ern per ature t
Density Data T h e experimentally measured densities for the pure hydrocarbons are given in Tables I and 11. The values listed in Table I11 were obtained by plotting the experimental data in a similar manner to that shown in Figure 3 and reading the values from the curve. For temperatures above 0' F. the densities are b e l i e v e d accurate to 0.015 per cent and, a t temperatures below 0" F., to 0.03 per cent. Table IV contains the experimental a n d c a l culated densities of the two mixtures. The densities were cnlculated from values in Table 111.
FIGURE 2. GLASSPIPETUSED FOR TEMPERATURES BELOW 0" F.
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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
TEMPERATURE
Vol. 34, No. 10
"F.
FIGURE 3. LIQUIDDENSITIE~ OF THE HYDROCARBONS
The experimental data and the values found in the literature for the hydrocarbons studied are plotted in Figure 3. PROPANE. With the exception of the densities by van der
Vet (IS), all literature values which do not agree with the new measurements are higher than the latter. The values given by van der Vet were the most recent and agree most closely.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
October, 1942 4
1243
liable explanation of the increased deviation, however, must TABLE I. EXPERIMENTAL DENSITIES OF PUREHYDROCARBONS wait on further work. Otherwise the mixtures investigated AT TEMPERATURES ABOVE 0" F. appear to act as perfect solutions. No data were found in the r Density, Grams per Go. literature for mixtures of the components reported here. Temp., Pro160nn1F. pane butane Butane Pentane Propylene Butene van der Vet (IS),however, reported the appreciable devia0.5294 0.5849 ... ... 140 0.4314 0.5035 tion of mixtures of propane and n-butane from perfect soluO
120 100 80 60 40 39.2 20 0
0.4530 0.4722 0.4906 0.5073
0,5199 0.5345 0,5486 0.5626
0.5442 0.5578
0.5240 0.4384 0.5522
0.5762 0.5886 0.6008
0.'5963 0.6082 0.6197
0.5709 0.5840
0.5968 0.6083 0.6194 0.6304 0.6411
0.'8518 0.6621
... ...
...
0.'6216
0.6000
0.'5396 0.5553 0.5710
0.6260 0.6386
TABLE11. EXPERIMENTAL DENSITIESFOR BELOW 0" F. -PropaneF. +0.2 -4.7
-12.2 -17.2 -24.4 -30.3 -38.6 -44.4
G./cc.
0.5521 0.5556 0.5606 0.5651 0.5690 0.5729 0,5784 0.5822
-1sobutanF. +0.2 -10.0 -16.6 -29.5 -41.6
-48.5
G./oc. 0.6007 0.6067 0.6105 0.6182 0,6252 0.6293
--ButaneO F. G./cc. +0.1 -13.7 -30.1 -35.1 -51.4
0.6105 0.6272 0.6360 0.6389 0.6477
...
tions.
Acknowledgment The research which is briefly outlined in the above report was sponsored by the Natural Gasoline Association of America as a project of its Technical Committee. The work was done TEMPERATURES under the direction of T. W. Legatski of the Phillips Petroleum Company, chairman of the N. G. A. A. Liquefied Petro-n-Pentane---. leum Gas Subcommittee. Densities from 0' to 60" F. were F. G./cc. determined at the University of Tulsa under the direction of +0.1 0.6620 -13.7 0.6690 W. R. Nelson. The densities from -50' to Oo and from -25.7 0.6735 60" to 140' F. were determined by M. R. Dean and L. R. -35.1 0.6796 -44.2 0.6839 Fruit of the Phillips Petroleum Company. -55.4 0.6898 0.'$1'35
O
Dana (6) claims a purity of the propane used of 99 per cent. Assuming the impurity to be isobutane, the calculated purity, based on the new densities reported here, would be 98.5 per cent. This shows that the agreement with the densities reported here is better than is at first apparent. If these values are assumed as correct, it would appear that the preferred densities by Egioff (7) and Maass (9) are somewhat high. ISOBUTAND. Again the values reported by van der Vet (18) are in good agreement with the experimental values reported here. Although Dana (6) reports densities somewhat higher than the experimental figures, a purity of only 97 per cent is claimed. Assuming the impurity wm n-butane, the calculated densities of Dana (6) for pure isobutane would agree closely with the experimental results reported here. Densities cited by Coffi (4) and Burrell (2) are coasiderably higher than the new measurements. The presence of n-butane, the most probable impurity, would cause the deviation found between the densities reported here and those reported by those authors. +BUTAND. The densities by Maass (9) and Huckel(8) are in good agreement with the new measurements. The results reported by Dana (6)agree fairly well for the middle of the temperature range but show large deviation at the extremes of the range. Densities reported by van der Vet (18) are lower than those previously reported and those given here. n-Pmm"T. The densities reported here and those given by Chavanne (a), Seitz (11), Dornte (6),Brown ( I ) , and Shepard (12) are in good agreement as shown in Figure 3. The maximum deviation which occurs in the temperature range of 40" to 95' F. is about 0.0003. Values given in the classical work by Young (14) were identical with those of this work at 32", 122", and 140' F. Young's values were higher, however, at 50" and 68" F. by 0.0003, at 86' F. by 0.0004, and at 104" F. by 0.0001. OLEFINS. The only available densities for propylene were those reported by Coffin (4) and later by Pall (IO). Figure 3 shows that the new measurements gave densities somewhat lower than those previously reported. Densities listed by Maass (9) for 1-butene and the new measurements are shown in Figure 3 to agree closely, except for that regiou around 30" F. With the exception of the propane-isobutane mixture at 100' F., the differences between the calculated and experimental densities shown in Table I V are within experimental error. The large difference for the propane-isobutane mixture at 100' F. might be due to an experimental error. A re-
TABLE 111. SMOOTHED DENSITIES OF PARAFFINS AND OLEFINS (IN GRAMPER Cc.) Temp., o F.
Propane
butane
160-
nButane
Pentane
140 130 120 110
0.4314 0.4421 0.4627 0.4625
0.5036 0.5120 0.5197 0.5272
0.5293 0.5368 0.5440 0.5509
0.5860 0.5909 0.5968 0.6026
100 90 80 60
0.4722 0.4813 0.4903 0.4990 0.5074
0.5344 0.5417 0.5488 0.5556 0.5625
0.5578 0.5644 0.5710 0.5774 0.5838
0.6083 0.6139 0.6194 0.6250 0.6304
50 40 30 20 10
0.5157 0.5234 0.5312 0.63S7 0.5456
0.5692 0.5757 0.5821 0.5884 0.5947
0.5901 0.5961 0.6022 0.6081 0.6138
0 -10 -20 -30
0.6522 0.5592 0.5660 0.6728
0.6008 0.6067 0.0127 0.6186
-40 -50
0.6794 0.6244 0.5858 0.6301
70
12-
Propylene
... ,.. ... ... , .. ...
1-
Butene
... ... ...
...
... ... ... ...
O.*$il5
0.'8000
0.6367 0.6411
0.5302 0.6389 0.5472 0.5563 0.5632
6.6065 0.6131 0.6196 0.8260 0.6324
0.6196 0.6251 0.6306 0.6361
0.6621 0.6671 0.6721 0.6770
0.5710
0.6386
0.6416 0.6370
0.6818 0.6866
0.6465 0.6517 0.6570
... ... . .. ... ...
... ... ...
...
...
TABLEIV. EXPERIMENTAL AND CALCULATED DENSITIES OF MIXTURES (IN GRAMPER Cc.) Mixture No. 1
2
7 2 0 ° F.-
Exptl.
Calod.
0.5641 0.6300
0.5646 0.6305
7 - 0 0 ' F.-
Exptl.
Calod.
0.5362 0.6073
0.5359
0.6076
-100'
Exptl.
F.Calod.
0.5052 0.5833
0.5040 0.5836
Literature Cited (1) Brown, G. G., and Cam. A. R., IND. ENQ.CRBM.,18, 718 (1926). (2) Burrcll, G.A.,and Robertson, I. W., J . Am. Chem. Soo., 37, 2188 (1915). Chrtvanne, G . , and Simon, L. J., Compt rend., 168. 1324 (1919). Coffin, C.C , and Maass. O., J . Am. Chem. SOC.,50, 1427 (1928). Dana, L. I., Jenkins. A. C , Burdirk, J. N., and Timms, R. C.. Refriu. Enu.. 12,No.12,387(1926). Dornte. R. W., and Smythe, C. P.,J . Am. Chem. SOC.,52, 3546 (lV30). (7) Egloff. Gustav, "Physical Constants of Hydrocarbons", A. C. S. Monograph 78, VoI. I, New York. Reinhold Pub. Gorp., 1939. (8) Huokel. W.,Kraemer, Agnes, and Thiole, F., J . prakt Chem., 142,207(1935). (9) Maass. O., and Wright, C. H . J . Am. C h . SOC.,43, 1098 (1921).
(10) Pall, D.B.,and Maass, O . , Can. J . Research. 14B.96 (1936). (11) Seits, W.,Altertherm, H., and Lechner, G., Ann. phys., [4]49, 85 (1916). (12) - . T.. Jr., J . Am. Chem. . . She~ard,A. F.,Henne. A. L., and Middey, Soo., 53.1948 (1031). (13) Vet, A. P. van der, I P Conar. modial p6troZe 2, Sect. 2, Phye. Chim.. r a j h w s , 519 (1937). (14) Young, Sidney, Sei. Proc. Roy. Dublin SOC.,12,414 (1910).
