INDUSTRIAL AND ENGINEERING CHEMISTRY
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Vol. 17,No. 12
Relation between Boiling Point and Some Other Properties of Petroleum Products' By J. B. Hill and S. W. Ferris T EATLANTIC ~ ~ F I N I N OCo.,PHILADELPHIA, PA.
HE development of the
On account of the high vapor Close-cut fractions from various crude petroleums vacuum assay distillavelocity, it was found necesshow interesting relationships between their boiling tion test, as suggested sary t o have the entire vapor ranges, as determined by the vacuum assay distillation in Bureau of Mines Bulletin line, including stopcocks, of test, and their viscosities, specific gravities, and re207 and developed in further at least 9 mm. bore. fractive indices. Data are included on five typical detail by Peterkin and Ferris, D i s t i l l a t i o n s were concrudes varying from a Pennsylvania crude to a highly has furnished an additional d u c t e d especially on five naphthenic Gulf Coast crude. I t is shown that, for and highly valuable means of crudes representing, respecfractions of the same boiling point as indicated by the comparing crude oils. Fortively: 50 per cent point on the vacuum assay distillation, as mer comparisons of oils of the crude varies from paraffinic to naphthenic, the A-A typical Pennsylvania like flash point have atviscosity, the coefficient of viscosity change with temcrude tempted to arrive at the same perature, the specific gravity, and the refractive index B-An Oklahoma crude typical of the high-grade Midconthing in a somewhat different all increase. The relation between boiling point and tinent crudes way. The fact that two other physical properties is a good indication of the C, D, and E-Three Gulf oils have t h e s a m e flash source of the oil. Coast crudes, designated, repoint does n o t , however, spectively,,Gulf Coast 1.2, and 3. from different fields of the show by any means that they cover the same boiling range, since the flash point is Gulf Coast area and showing different degrees of naphthenic necessarily governed by the boiling point of the first few per characteristics cent of the oil and is almost independent of the boiling point In addition to straight runs of the five crudes, additional of the main body of the oil. As an extreme case, a residuum runs were made on partially dewaxed Pennsylvania and Midand a close-cut overhead may show identical flash points, continent crudes, On account of difficulty in dewaxing the but will be, of course, widely different in the characters of the straight crude, the procedure followed was to make an overoils contained in them. head cut by vacuum and steam-vacuum distillation, going This paper presents a collection of data obtained by de- 5 per cent deeper into the crude than the viscosity information termining the physical properties, including vacuum assay was to be carried. This overhead was cut back with an distillation of a large number of distillate fractions obtained equal volume of 52' A. P.I. naphtha, chilled to about -15" from various crude oils. The fractions on which the data C. for 3 hours, and filtered in a cold filter. The dewaxed oil, were obtained were prepared by laboratory distillation on a after removal of the naphtha, was replaced in the flask, which small scale. These distillations were run, for the most still contained the bottoms, redistilled, and collected in cuts. part, under vacuum without any attempt a t fractionation. The distillate from each of the seven runs was taken off in The very heavy fractions which fail to come over below crack- fractions representing about 5 per cent of the crude. The ing temperatures a t a pressure of about 10 mm. were distilled odors and also the assay distillations showed that cracking over with vacuum and steam. had been successfully avoided. The fractions were examined for their physical properties, especially their specific gravities, Method Saybolt viscosities a t 100" and 210' F., refractive indices, and vacuum assay disThe v a c u u m a n d tillations. t? steam distillations were Two of the cuts from carried out in the set-up M i d c on t i n e n t crude s h o w n i n F i g u r e 1. were of such high wax This consists of a 3-liter content that the visflask connected with cosity a t 100' F. could t w o c o n d e n s e r s in not be directly measseries, the first being ured. It was thererun hot to condense fore necessary to d e only oil, and the sectermine these viscosiond ice-cooled to insure ties a t 130' F. and practically c o m p l e t e transfer them to 100' c o n d e n s a t i o n of the F. In order to do this, water and thereby to three wax-bearing Midcut down the load on continent cuts and two t h e vacuum pump. heavier c u t s from which the wax had been 1 Presented before the partially removed were D i v i s i o n of P e t r o l e u m run a t both temperaC h e m i s t r y a t the 69th Meeting of the American tures and the values Chemical Society, Baltimore, plotted against each Md., April 6 to 10, 1925. other. The viscosities * Page 1248, this issue. Figure 1-Apparatus for Vacuum-Steam Distillation
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Table I--Properties of Fractions from Gulf Coast 1 Crude SAYBOLT VISCOSITY ASSAYDISTILLATION AT
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Cut 6
7 8 9 10
11 12 13 14 15 16
3OOXBOILING POINT Y 5.
%
-
SAYBOLT VISCOSITYS+XV
20
10
50%801LING P O i N T BIOmm -'G
a t 100" F. of the two cuts from Midcontinent were then read from the curve. The accuracy of this method was further checked by determining the viscosities of one of the cuts a t 130",120°, l l O o , and 104" F., the last figure being thelowest temperature to give trustworthy results. These viscosities were plotted against temperature and the curve extrapolated to 100" F. The two methods were found to check very closely. Results
The detailed data on the fractions from the Gulf Coast 1 are shown in Table I as an example of the data on the seven runs.
S O X B O I L I N G P O I N T C I 0 m m . - ?2
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At At Sp. gr. Refractive 10 100'F. 210'F. at index Pour Start 50 7 Sec. Sec. 15.5'C. at 25'C. OF. OC. C ! 39 0.8646 1.4723 91 127 45 0.8784 1.4809 121 152 55 0.8889 1.4878 141 174 0.8970 1.4924 73 166 196 102 0.9025 1.4965 182 216 154 0.9080 1.4995 201 233 251 44 0.9128 1.5023 208 253 419 51 0.9179 1.5051 0 235 268 732 63 0.9227 1.5077 5 257 291 1322 82 0.9283 1.5110 10 268 313 2682 120 0.9338 1.5156 15. 279 339
MM. End
'C. 203 220 246 271 287 300 321 324 347 365 395
%
etend 98.5 99.0 99.0 98.5 98.0 98.5 98.0 98.5 98.0 98.0 98.0
I t will be noted from the data that the distillation ranges of the several fractions vary from 75" to 115' C. It is general experience that a fraction boiling within as close a range as this has properties approximating those of a fraction of much closer boiling range but having the same 50 per ccnt point. In this case, the lighter boiling front end and the higher boiling tail end appear to balance each other, so that, as an approximation, the total fraction may be considered as having a boiling point corresponding to the 50 per cent point on the assay distillation. It would be expected that two reasonably close boiling fractions prepared from the same crude and having the same 50 per cent point on distillation would contain approximately the same proportions of the various series of hydrocarbons, and would therefore exhibit similar properties. Correspondingly, the fundamental differences between two crudes are shown up much better by comparing corresponding close boiling fractions-i. e., fractions of the same 50 per cent points-than by comparing the properties of the crudes themselves or fractions representing some arbitrary cut, or fractions of corresponding viscosities, etc. For purposes of comparison, therefore, Curves 1, 2, 3, and 4 have been drawn, plotting, for the five crudes investigated, the 50 per cent boiling point from the vacuum assay distillation a t 10 mm. against the Saybolt viscosity a t 100' F., the Saybolt viscosity a t 210" F., the specific gravity, and the refractive index, respectively. The facts shown by the curves are not particularly new, but
5 0 % B O I L I N G P O I N T @lOmm-'C.
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are rather strikingly brought out. Curve 1, giving Saybolt viscosity a t 100' F. against boiling point, shows a decrease in viscosity, for the same boiling point, as the naphthenic character of the crude decreases and its paraffinic character increases. Conversely, for the same viscosity the naphthenic crude has the lowest boiling point. This, of course, accords directly with the general experience that the naphthenic crudes give low flash points, the flash in fractions of this kind naturally increasing or decreasing with the boiling point.
Vol. 17, No. 12
sylvania fractions show little difference. The same relationships are brought out in Curve 4, showing refractive index against boiling point. Application
The relationships brought out above should find a usefulness in many different ways. For example, it is possible on any given crude definitely to tie up the viscosity with the boiling points of the fractions so that from the vacuum assay distillation of the viscosity oil it is possible to estimate yields of oil of various viscosities in the same way that the yield of naphthas are commonly estimated, by an inspection of the assay distillation of the light cuts. The relationship between boiling point and the other properties should also give considerable help in determining the composition of an unknown lubricating blend.
Gallium-in-Quartz Thermometer Graduated to 1000" C.' By Sylvester Boyer THOMSON RESBARCELABORATORY, GENERALELScrarc Co., WEST LYNN, M A $ %
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/Bo 220 260 JOO 3+0 5 0 X B O I L I N G POINT BIOmm.-eC.
QBO
The fact that the removal of the wax from the Midcontinent crude raises its curve more nearly to the Gulf Coast is due to the concentration of the naphthenic constituents by removal of some of the paraffinic constituents, thus making the crude more naphthenic in character. A few miscellaneous experiments, in which the wax was removed fairly completely, brought the Midcontinent curve very neakly up to the Gulf Coast 1 curve. The fact that the removal of wax from the Pennsylvania fractions has little effect on the curve is extremely interesting. Curve 2, showing the 210" F. viscosity against the boiling point, brings out exactly the same relations as Curve 1, except that at the higher temperature the curves are brought closer together, owing to the higher coefficient of viscosity change with temperature in the naphthenic oils. This fact is shown very well by the following data taken from the curves :
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EMPERATURES much above 700" C. have not h e r e tofore been recorded by direct-reading thermometers. The upper limit of the mercury-in-glass thermometer, because of the marked hysteresis of glass, is about 500' C. Mercury-in-quartz thermometers reading to about 700" C., using gas pressure for raising the boiling point of the mercury, have been manufactured in Germany in limited numbers. Above this range Dufour2 attempted to substitute tin for mercury, but because of the relatively high freezing point it was not adequate. The range in temperature above the mercury limits has been measured by changing electrical properties of certain metals with changing temperatures. These methods are troublesome, since the apparatus requires frequent rechecking. The first problem, therefore, in the production of a thermometer was the choice of a suitable filling liquid. The Filling Liquid
Previous work3 on the purification and properties of gallium revealed a number of changing properties with varied treatments. More recent investigations on the properties of gallium indicated its possible use as a thermometric liquid. Heretofore the wetting of glass and quartz surfaces by liquid gallium had prohibited its use for this purpose, but the change in this property of the metal was observed when changing the gas pressure above the metal, increasing its purity, removing oxide and water films, and freeing it from absorbed or dissolved gases. This paper briefly recounts these experimental observations. Properties of Gallium
60 Per cent Boiling Point of Fraction with: Vis./lOOo F. 1000 Vis./210° F. 58 0
Gulf Coast 3 Gulf Coast 2 Gulf Coast 1 Midcontinent Pennsylvania
c. -.
243 268
303 329 351
0
c. ~.
243 263 283 293 313
Curve 3, plotting the specific gravities against the 50 per cent boiling points, shows the same relationship between the individual curves except that the differences in gravities are more nearly constant over the range of boiling points. Again the partially dewaxed Midcontinent fractions are brought closer to the Gulf Coast while the part,ially dewaxed Penn-
As reported in the current literature, gallium melts at 29.7" C. and boils at approximately 1700' C. It may be undercooled to 1 or 2 degrees above 0" C. before solidifying. The metal, like aluminium, easily becomes coated with surface oxides which protect it from further oxidation. Lockyer4 noted that no gas was evolved upon heating in uacuo. 1
2
Received October 16, 1926. Burgess-LeChatelier, "High Temperature Measurements," 1911, p.
365. 8
4
Richards and Boyer, J . Am. Cham. Soc., 43, 274 (1921). Chem. News, 40, 101 (1870).
