Significance of A. S. T. ]MI. Distillation Curve '
M. G. BLAIRAND R. C. ALDEN Phillips Petroleum Company, Bartlesville, Okla. The fifth a x i s is p r o v i d e d FEW years ago it was Previous contributions relating the A . S. T. M . with two temperature scales. felt t h a t e x c e p t i n a distillation curve of motor fuels to automobile T h e scale on t h e l e f t of the very empirical way the performance are briefly reviewed. Mention is axis i n d i c a t e s the atmospheric A. S. T. M. distillation (1,Z) was made of the use of A . S. T. M . distillation curves temperature a t or above which a practically meaningless test, in estimating composition, gravity, and vapor d i f f i c u l t y from c r a n k case and a widespread s e a r c h was dilution, if i t occurs a t all, will carried on by many engineers to pressure of natural gasoline. Summary charts be limited to that part of the find m o r e comprehensive proare presented in the foregoing Jields. Graphs warming-up period d u r i n g cedures which would simulate are also presented, and briefly described, by which it is necessary to use the the condition of actual operameans of which the A . S. T. M . distillation curve choke. The scale on the right tion. The r e s u l t was, as one of motor fuels can be used to estimate the comof the axis is an index of the a u t h o r i t y (34) has s a i d , "to atmospheric t e m p e r a t u r e a t correl-ate the results of these position, vapor pressure, and minimum temor above which t h e r e will be t h e o r e t i c a l l y more sound but perature at which incipient vapor lock might loss of Dower as a result of too more difficult tests with the rebe expected. rapid Gaporization of the fuel sults obtained by the ordinary in the fueling system. A. S. T. M. (Engler) distillation." Performance characteristics have been correlated with An examination of the distillation curves representing averA. S. T. M. curves by many investigators (1-36). The Co- age motor gasolines in Figure 1 indicates that, in summer, operative Fuel Research Committee (American Petroleum gasolines give performance relatively much superior to Institute, Society of Automotive Engineers, and National winter results. At the same time it is more difficult to build Automobile Chamber of Commerce) has been responsible for much of the detailed work in this field. The most complete relationship, perhaps, is the one shown in Figure 1 developed by Brown (17). There are five vertical axes located a t various percentages evaporated along the path of the distillation curves. Each of these axes is graduated in O F., atmospheric temperature. The procedure in using this chart is to plot the A. S. T. M. curve across the figure and note the temperature reading a t its intersection with each of the axes. The axes from left to right, except the fifth, indicate the atmospheric temperatures above which the gasoline under examination provides the following features of performance : (1) possible starting (8 per cent), (2) easy starting (10 per cent), (3) quick warming-up characteristics (35 per cent), and (4) good acceleration, without choke, steady driving (60 per cent).
A
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an entirely satisfactory summer gasoline because of the economic necessity of marketing the volatile fractions as produced. The balance of supply against demand now results in summer gasolines with starting qualities, formerly considered highly satisfactory for winter gasolines, but uncomfortably close to the limit of vapor lock. In this dilemma, automobile manufacturers can assist materially by making the simple changes (13) necessary in automotive fuel systems to minimize vapor-locking tendencies.
COMPOSITION OF MOTORFUELS Extending the value of the A. S. T. M. curve still further, a means has been devised to estimate graphically the butanes and lighter, pentanes, hexanes, and heptanes and heavier contents of motor and aviation gasolines. This graph is presented in Figure 2. Butanes and lighter content has been found to have a close relationship with the 10 per cent VOLUME PER CENT EVAPORATED evaporated temperature. This relationship is expressed by FIGURE 1. EFFECTIVE VOLATILITY REQUIRED FOR EQUIVALENT PERFORMANCE AT IRDICA'IED ATMOSPHERIC TEMPERATURE curve A of Figure 2, which indicates a correlative tempera-
INDUSTRIAL AND ENGINEERING
560
FIGURE3. CATED BY
REID VAPORPRESSURE AS INDIRELATIONSHIP A AND B FACTOR
ture for each 10 per cent temperature, a t which a percentage equal to butanes and lighter will have been evaporated. Pentanes content may be determined directly by reading the percentage evaporated a t the intersection of the A. S. T. M. curve with curve B, and deducting the previously determined butanes and lighter. Hexanes content is the difference between the readings on curves B and C, whereas heptanes and heavier content is determined by difference. The relationships represented by CUNeS A , B, and C were established by careful study of the A. S. T. M. curves in conjunction with composition data of several hundred gasoline products. The composition analyses of these gasolines were determined in a column of the type described by Oberfell and Alden (87) and Podbielniak (23). I n the case of butanes and lighter predicted by the curve A relationship, it was found that the temperature a t which percentages equal
CHEMISTRY
Vol. 25, No. 5
The temperatures a t which quantities equal to pentanes and lighter, and hexanes and lighter were distilled off, for the products investigated, covered a sufficiently narrow range so that a direct relationship with the A. S. T. M. curve could be established for the prediction of these fractions. These relationships are expressed by the direct intersections of the distillation curve with curves B and c. An application of these means for graphical analysis is to be found on Figure 2. A distillation curve (dashed) has been plotted which shows a 10 per cent evaporated temperature of 141 O F. From curve A it will be seen that a t this 10 per cent temperature a temperature of 119' F. should cause the evaporation of a quantity equivalent to the butanes and lighter content of the product. The distillation curve, a t this temperature (119' F.) shows 4.7 per cent evaporated, which is the estimated butanes and lighter content. The intersection of the distillation curve with curve B indicates 14.9 per cent which, after deducting the estimated butanes, leaves a pentanes content of 10.2. The same procedure applied to curve C shows 27.8 per cent evaporated of which 14.9 per cent is pentanes and lighter, leaving a hexanes content of 12.9 per cent. By difference there is 72.2 per cent heptanes and heavier components. Comparison of this estimated composition with the actual composition as shown by laboratory analysis shows the following agreement : Butanes and lighter Pentanes Hexanes Heptanes and heavier
LABORATORY GRAPHICAL z 9% .5.2 4:7 10.6 10.2 12.9 12.9 71.3 72.2
DBYIATION
z .-
-0.5
-0.4 0.0
+0.9
Table I, which is a list of gasoline samples of widely varying characteristics picked a t random from several hundred fractional analyses, gives a comparison of actual and graphical analyses which illustrates the reliability of determinations made from Figure 1. The A. S. T. M. distillation data used in determining these relationships were plotted on coordinate paper ruled 20 X 20 to the inch. The ordinate representing distillation temperature was scaled so that each inch was equivalent to a change of 20" F. and the abscissa representing percentage evaporated had a range of 10 per cent to the inch.
7. EVAPORATED AT 140'F
. h ~ B T W
B
A
FIGURE4.
GRAPHICAL ANALYSIS OF NATURAL GASOLINE
to butanes and lighter would be evaporated varied over a wide range as the character of the product changed from high to low effective volatility. This circumstance made necessary an intermediate correlative for which the 10 per cent evaporated temperature was used, thus bringing about the relationship expressed by the curve.
REIDVAPORPRESSURE The Reid vapor pressure (3) of gasolines can be estimated from the A and B values derived from the A. S. T. M. distillation curves by means of Figure 2. This relationship is shown in Figure 3. There were more than three hundred
May, 1933
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561
TABLEI. COMPARATIVE ANALYSESILLUSTRATINQ RANQEAND ACCURACYOF FIGURE 2 (In per cent) r-
-ACTUAL
COMPOSITION ANALYSES QRAPHICAL
IDENTIFIButanes & Heptanes & Butanes & Heptanes & REIn VAPORPRESSURE CATION~ lighter Pentanes Hexanes heavier lighter Pentanes Hexanes heavier Actual Graphical Deviation M. N. 8.0 11.6 11.8 +0.2 20.5 18.8 22.8 14.3 53.7 52.7 1 9.2 A. N. 2.3 28.5 8.1 8.3 +0.2 35.9 33.3 2 0.6 29.2 36.9 33.3 M. N. 9.2 0.0 4.7 20.3 9.2 18.3 56.7 20.4 18.2 56.5 3 4.9 A. N. 11.4 11.2 -0.2 6.2 33.3 29.0 31.5 35.9 27.2 32.2 4 4.7 R. A. 6.5 6.8 +0.3 2.1 17.4 29.9 50.6 13.2 29.4 5 2.5 64.9 R. A. 7.8 7.1 -0.7 2.0 19.8 32.9 45.3 18.0 33.5 6 2.8 45.7 R. M. 5.4 9.4 9.2 -0.2 13.0 13.8 11.1 15.0 66.9 67.8 7 7.0 N. G. 3.8 43.2 11.2 10.6 -0.6 32.0 21.0 89.4 37.2 19.9 8 3.5 M. N. 8.2 20.4 17.2 54.2 11.3 11.9 +0.6 21.7 16.1 54.8 9 7.4 R. M. 3.0 5.3 4.5 -0.8 6.5 9.9 6.9 Q.9 80.2 80.6 10 3.0 R. M. 4.5 9.7 11.6 8.6 7.8 -0.8 74.2 11 5.4 10.0 12.5 72.1 R. A. 1.0 13.6 5.6 5.3 -0.3 34.4 51.0 13.7 38.3 46.3 12 1.7 R. M. 3.5 10.4 6.2 6.6 +0.4 14.1 72.0 13 3.0 8.4 14.6 74.0 M. N. 2.1 14.3 6.2 6.2 0.0 17.2 14.7 15.4 68.2 14 0.0 68.1 N. G. 4.3 52.2 12.3 11.7 -0.6 25.9 17.6 15 0.7 63.1 29.9 16.3 , R. M. 3.5 7.5 5.7 5.6 -0.1 8.0 13.2 76.0 11.9 77.1 16 2.8 R. M. 74.3 5.4 9.3 8.4 8.8 +0.4 8.4 11.3 10.7 74.6 17 6.0 R. M. 71.9 4.3 9.9 7.2 7.5 +0.3 9.6 14.4 12.3 73.5 18 4.1 R. A. 2.9 11.4 26.2 6.2 -0.4 10.8 23.2 63.0 59.5 6.6 19 3.0 N. G. 12.5 -0.4 43.2 23.9 28.0 8.0 39.8 12.9 26.5 25.7 20 4.9 M. N. = motor natural gasoline: A. N. = aviation natural gasoline: R. A. refinery aviation gasoline; R. M. refinery motor gasoline: N. G. natural gasoline. SAMPLE
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gasoline samples used in the determination of this relationship. For nearly 90 per cent of these samples the accuracy of graphical Reid vapor-pressure determinations was within the range of accuracy of the laboratory determination. The samples of Table I show something of this accuracy. The relative number of extreme products is much greater in this table than was the case with the samples used in constructing the plate. Illustration of the Reid vapor-pressure determination may be accomplished by the use of the A and B values in the analysis above. These values 4.7 and 14.9, respectively, applied to Figure 3 give, as the estimated Reid vapor pressure, 8.2 pounds in comparison with an actual value of 8.6 pounds. The deviation in this case is 0.4 pound per square inch. COMPOSITION OF NATURAL GASOLINE Figure 4 (28)correlates the A. S. T. M. distillation data of natural gasoline with composition, A. P. I. gravity, and Reid vapor pressure. The basic relationships shown in Figure 4A me between the percentages evaporated a t 100" and 140' F. of the A. S. T. M. distillation, and the butanes and lighter content and pentane ratio or percentage pentane occurring in the base material after removal of butanes and lighter. The intersection of the lines representing any two of these four factors is the intersection also of the lines representing the other two factors. Thus, the intersection of 40 per cent evaporated a t 100" with 65 per cent evaporated a t 140" F. is also the intersection of 26.8 per cent butanes and lighter and 0.423 pentane ratio. Figure 4B relates the ordinates of Figure 4A to Reid vapor pressure and A. P. I. gravity. The extension a t the right of Figure 4B is for the purpose of estimating the effect of propane inclusion on the Reid vapor pressure or, conversely, of estimating the propane content from the determined Reid vapor pressure. Thus, in the example cited in the description of Figure 4A, the Reid vapor pressure of the natural gasoline is 23 to 29 pounds with propane inclusions from 0 to 3 per cent. Conversely, if the observed Reid vapor pressure had been 26 pounds, the propane content would be estimated at 1.5 per cent. The A. P. I. gravity would be estimated a t 85.3". Figures 4A and B have been combined, enlarged, and printed in colors, and are being distributed by the Refinery Supply Company, Tulsa, Okla. The A. S. T. M. distillations used in determining the relationships were plotted on coordinate paper ruled 20 x 20 to the inch. The ordinate representing distillation temperature was scaled so that each inch was equivalent to a change of 10" F., and the abscissa representing percentage evaporated had a range of 10 per cent to the inch.
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INCIPIENT VAPORLOCK In studying the problem of vapor lock in the writers' laboratory, seventy-seven gasolines, varying widely in physical characteristics, have been subjected to the following test procedure in a Waukesha knock-testing, single-cylinder engine of early design. Cool gasoline from the sample source
VAPOR EQUIVALENT
OF VAPORLOCKWITH FIGURE 5. CORRELATION VAPOREQUIVALENT
passed through the bowl and was progressively heated by means of a water bath close to the jet. Vapor locking was determined by sustained loss of speed and power, and the temperature of the gasoline into the jet was then recorded as the vapor-lock temperature. Figure 5 shows a plot of an arbitrary vapor equivalent against the temperatures thus observed. The vapor equivalent was determined from Figure 2 according to the following formula: B - A A + - 4
C - B + T
Except in a few cases, vapor-lock temperatures for individual samples are within 5" F. of the curve drawn through all points. Seventy per cent of the samples are within 4' F. Obviously the test procedure outlined above does not dupli-
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cate tile rnany varisbles encountcreed under actual driving conditions, most of which are conducive to minimizing vapor lock. Motor gasoline in use is usually inspected as it enters the automobile tank. Evaporation in the tank and on the way to the hottest point in the fuel system is a matcrial and extremely variable factor. Nevertheless, it is believed that tlic vapor-lock temperatures represent a condition of incipient vapor lock and may be taken as the minimum fuclsystem temperature at which vapor look fiiiglit be encountcreed under conditions quite iavorahle to the phenomenon. LITERATURE CITED
124 (1929). (5) Bridgeman, 0. C., J . Soc. Automofive Engrs.. 22, 437 (1928). (0) Ibid., 23, 478 (19%). (7) Bridgeman, 0. C., ant1 hlrlrioh, E. W..Ibiil.. 27, 93 (19Sll). (8) Bridgeman, 0.C . , Aldrich. E. W.. and White. H. S., Am. I’rtroleuni Inst., P ~ c 10th . Ann. Moofinp, 11, ?To. 1. See. 111, 4 (1930). (91 . . Bridaeman. 0 . C.. Aldrioh. E. W.. sad White. If. S.. J . Sac. Au~omo1i;e E w T ~ . ,24, 488 (1929). (10) Bridgeman, 0. C., and Cragoe, C. S.. Am. Polroleurn Inrl., Proc. 8th Ann. Meeting, 9, No. 7, 54 (1927). (11) . . Brideeman. 0.C..and White. H. 5.. J . Soc. Aulornofive Enom.. 28,- 315 ‘(isaii. (12) Ihid.. 29, 447 (1931). (13) Ibid.. 30, S2D (1932). (14) Brooks. D. B., Ibid.. 24. 609 (1929). (15) Brown. A. C., andCsbe, G. C.,Trans. Am. I m f . C4sm. Enpis., 21, 91 (1928). (16) Drown, G. G., Pmc. Am. Soo. Tesfing Materiala (Atlentio City Meeting). June, 1930.
1.01 2 5 , No 5
Ann. Connenlion, May, 1931, p. 75 (ohart). (18) Brown, G. G., Univ. Mioh., Ene. KeseorehBvll. 7.46, 53 (1927). (19) Ibid.. Bull. 14 (May. 19301. (20) Brown. G. G.. and Skinner, E. M., IND. ENG.CHSX, 22, 278 (1930). Bruoe. C . S.. J . Soc. Aufomotive Engrs., 27, 275 (S!WIj. Bur. Mines, Semiannual Sumeya of hlotor Gnsolines. Cragoc. 0.S.. &nd Eisingor, J. C.,Ibid., 20,363 (1927). Edgar, Graham, IIill. J. B..and Boyd. T. A.. Am. Polroleurn Inat.. Pmc. lldh ..la%. Meeling. 21, No. 75, Seo. 111,D.46 (1930). Druse, W. A,, INS. EN. CHPX., 15, 796 (1928); Oil Cas. J . , 22,86 (1924): Pelroleurn Ape, 12, No. 10, 20 (1924); Chom. & Met. Encl., 29, 970 (1928,and 30, 304 (1924). J&niee,W. S., J . SOC.Automofiee Enprs., 18, 501 (1926); Am. Pelroloum Insf. Bull., 7, No. 27, 117 (1926); Nall. Polroleurn Ne.08. 18, No. 7, 85 (1926). Oborloll, G.G..snd Alden. R. C., Oil Ga6 I..27, 142 (Oct. 18. 1028). (28) Pocoek. L. A,, and Blair, M. G., Nafl. Pebolotm News, 24, No. 20, 37 (1932). (29) Podbiclniak. W. J., Oil Gas J . , 28, 38 (Jan. 17. 1Y29). and 29, 235 (Oct. 2,1930): IND.ENO.CBEM.,Anal. Ed..3,177 (1931). (30) Stevenson, R., snd Babor. J. A,, IND.E m . Camr., 19, 1361 (1927). (31) Stevenson. R..and Stark, H.J.. I b d . , 17, 679 (1925). (32) Whatrnough, W. A.,Ibid.. 18, 609 (1926). (83) Whstrnough, W. A., Proc. Inst. Autornofiw Enera., 17, 346 (1932): IND.ENG. Caex.. 18. 43 (1926); Automotive Eng., 17, 15, 452, 484 (1926). 1%) Wilson, R.E., Oil Gas J., 29, No. 9, 40, 98, 100; No. 10, 38, 127-8 (1930). (35) Wilson. R. E., and Bernsrd. D. P.. J. Iirn. ENQ. C ~ M .13, , 906 (1921). (36) Ibid., 17, 428 (1925); J . Soc. Aulonol~ueEngrs., 12. 287 (1923). Rsccwvxo October 13, 1932. Presented before the Division of Petroleum Chemistry st tbe 84th Meeting of the American Chemiasl So$iety, Denver Cnlo , Awn* 22 to 26, 1932.
The Dutch Chymisls Through the courtesy of Dr. Charlos A. Browne we are able to add a new artist-Jan Steen (162&-1679)-to those whose work we are reproducing from month to month, in this e s ~ efrom an etching by Bouvier. Oh*ously, the “Chief Chemist” is trying to make gold, hence the tears of his wife, whose jewelry is being sacrificed in the crucible. Steen has another similar painting which we shell reproduce later.
Orders fox photographic prints 8 by 10 inchheo s t $1.50, and 18 by 20 inches at $4.00, of thia etohing (No. 29) should be sent with advanoe wyment t o D. D. Berolnheimer, 50 Eaat 41sl St., New York. N. Y. Sea o w March. 1933, h u e , p g s 302. for complete l i s t of the preview reproduotiom In the ~ e r i e a .
