792
INDUSTRIAL AND EYGINEERING CHEMISTRY
time consumed in the glass tank is considerably greater, about 48 hours being required for freshly introduced raw material to find its way to the forehearth outlet.
Inspection Inspection is provided to remove any out-of-shape or offsize bulbs, as well as those containing bubbles, stones (unmelted mix), or strains as revealed by examination under polarized light. The character of the rejects is the governing factor in controlling the melting operation and the speed of the machine, since the cycle moves too swiftly to be followed in any other way. The inside frosting of the completed bulbs is accomplished by spraying them in racks of one hundred with hydrofluoric acid solutions in three doses-the concentration of the acid used in each cycle being successively weaker-and finally washing them clean with water. By using several successive acid washes, the weaknesses set up in the thin glass by a single treatment are eliminated and the pleasing effect of diffusing the light from the filament is secured. After final inspection the glass bulbs are ready for the lamp industry, whose automatic machines assemble the essential parts of lamps, vacuum tubes, or photoelectric cells into the bulbs.
VOL. 28, NO. 7
Because numerous sizes and styles of bulbs are required in quantities large enough to justify manufacture on an automatic blowing machine, its working parts are assembled on what is virtually a railroad car runnihg on light rails. Several such assemblies are at all times ready to be pushed up to the forehearth of the glass tank and set in motion. The assembly of the machine or its reassembly to make bulbs of different sizes or styles is a tedious operation requiring several men over a period of some hours to put in place the required molds and orifice plates and to adjust the air blasts to fit the requirements of a particular product. However, this assembling job is done on a spare machine, and, when it is ready for use, the shift from one machine in operation to another producing a different bulb is accomplished with barely half an hour's interruption of production. Ordinarily two machines taking glass from two different forehearths of the same tank are kept running. Each of them turns out half a million completed bulbs in a 24-hour day. The glass tank must be kept hot continuously since the congealing of the mass of glass in it is a major disaster, but operation of the blowing machines is adjusted to production and is continued from 5 to 7 days per week. RECEIVED May 1, 1936.
GASOLINES AND GASOLINE FRACTIONS SUSCEPTIBILITY TO TETRAETHYLLEAD AND ANILINE
I
N A PREVIOUS paper (9) the high octane number and high tetraethyllead susceptibility of certain fractions obtained in the efficient fractionation of straight-run gasolineswerementioned. Studies on the lead susceptibility of various types of gasolines were made by several investigators (Its,4, 5 ) ; Campbell and eo-workers ( 2 ) studied the lead susceptibility of pure compounds. Natural and straight-run gasolines are more responsive to tetraethyllead than other types of gasolines. However, the higher the octane number of the gasoline the smaller the increase in octane number per cubic centimeter of tetraethyllead added. This behavior, together with the comparatively poor lead susceptibility of cracked and polymer gasolines, renders the preparation of stable fuels with an octane number of 90 or higher a difficult matter. Campbell showed that there are hydrocarbons with not only a high octane number but also a high lead susceptibility. Some of these compounds are known to be in petroleum (6, 8). I n view of the latter results and the work done in this laboratory on the chemical composition of the gasolines reported here, the high values obtained for octane number and lead
C. 0. TONGBERG, D. QUIGGLE, E. M. FRY,AND M. R . FENSKE The Pennsvlvania State Colleae. - State College, Pa.
susceptibility of certain fractions of these gasolines are not entirely unexpected.
Experimental Procedure The gasolines were all fractionated in a column of seventyfive theoretical plates at a reflux ratio of 40 to 1. That is, the entire gasoline was fractionated by batch operation to obtain approximately two hundred consecutive fractions. This careful and efficient fractionation was done as part of a program on the composition of gasolines. The charge was 45 gallons. The properties of the original gasolines are given in Table I. Blends of the fractions obtained from each distillation were made by combining successive fractions. Only those fractions of high octane number and suspected high responsiveness to tetraethyllead were blended. The octane numbers were obtained by a series 30B Ethyl knock testing engine operating a t 345" F. jacket temperature and a t a motor speed of 900 r. p. m. (procedure 345) (9). The knock ratings of secondary reference fuels C-9 and A-4 were obtained on this engine by comparing with the primary standards. These values and certain others given
JULY, 1936
IXDUSTRIAL AND ENGINEERING CHEMISTRY
in Table I1 indicate the relationship between the engine used and the C. F. IZ. engine operating under the motor method. 'rABLE
I.
PROPERTIES O F ORIGINAL
A. S. T . Initial Gasoline Gravity b. p. F. 74.0 95 \Ir. Va. natural Hradford straight-run 6 2 . 3 104 111 Mich. naphtha 71.4 108 Yates straight-run 54.9 57.7 112 A a Tetraethyllead.
-4.P. I .
TABLE
GASOLINES
-Octane No. byProcedure 345 Gasoline 1 cc. M. Engler Distn. Final Original T. E. L. "/ gal. h. p . gasoline 50% a F. F. 69 310 57 173 258 410 41 53 274 41 60 185 410 59 66 294 52 64 246 432
+
11. COMPARISON OF OCTAXE NUMBERS BY MOTORAND SERIES30B METHODS
--
Octane Number--.---Procedure Ethyl Gas C. F. R. motor Corp.
Fuel Secondary reference fuels: A-2
75 77 74
70 79
76 78 74
44 59
..
..
41 59
67.5 61
.. ..
66 52
62.5 56 69
.. ..
64 57 60
44 41
c-7 C-S c-9 Pa. straight-run gasoline P a t e s straight-run gasoline Yates straight-run gasoline 1 cc. T.E.,L./gal. Straight-run gasoline A 1 cc. Straight-run gasoline A T. E. L./gal. W. Va. natural 711. Va. natural 1 cc. T. E. L./gal.
+ +
+
345--
48 41 40
A-4
..
..
..
R.
Pa. State
46 41
48
-4-3
c. F.
Octane numbers above 78 were obtained by blending fuel C-9 with isooctane or benzene to obtain secondary reference fuels which were checked against the primary standards of n-heptane akd isooctane. In a few instances the primary standard was used directly to rate the unknown fuel. Octane numbers below 40 were obtained by blending a ba,se gasoline of low octane number with reference fuel A 4 obtained from the Standard Oil Company of New Jersey and checking the blends with the primary standards. Therefore all octane numbers obtained were actual octane numbers and not socalled blending octane numbers.
793
prepared from different gasolines have considerable differences in octane number and lead susceptibility. This is, at least in part, due to the fact that different hydrocarbons as well as perhaps different sulfur compounds are present and boil in the same ranges. These observations on knock are entirely in agreement with more complete physical and chemical studies being made on these fractions. The work on the constitution of these gasolines in this laboratory has shown that the Yates gasoline contains a high proportion of naphthenic hydrocarbons-i. e., cyclohexane and cyclopentane derivatives-and fewer paraffinic hydrocarbons. This work further shows that there are considerable differences in the compounds present even in the paraffinic gasolines. It should be remembered in the high octane number region that not only is it difficult to obtain reliable octane numbers with the knock-testing engines now in use, but also that as far as ultimate engine performance is concerned, octane numbers, as well as changes in high-octane values, are much more important than in the lower portion of the octane scale. This is because considerably greater changes in compression ratio are possible for a given change in octane number in the high part of the octane scale than in the low part. For these reasons this work was intended to point out briefly the general and more important characteristics of these fuels rather than to place emphasis upon any particular fraction or any particular octane number. There still remains a large amount of work to be done before all the facts and observations relating to these materials can be adequately formulated and explained. The previous treatment of the gasoline, and particularly the presence of sulfur compounds, markedly influences the responsiveness of gasoline to tetraethyllead (6, 7). Becausc of this the sulfur content of certain fractions were obtained. These values are as follows: Yates (97-145" F.) 0.05 per cent; Bradford (97-142" F.) 0.05; Yates (162-192" F.) 0.03; Bradford (165-189" F.) 0.15; Yates (211-237' F.) 0.08; Yates (274-283" F.) 0.10; Yates (319-338' F.) 0.20 per cent. In view of these results and the work of Schulzc
Results The results obtained on the addition of tetraethyllead or aniline to various blends of the gasoline fractions are given in Table 111. The results show that blends from certain gasolines are very responsive to tetraethyllead and that even high-boiling fractions may behave similarly. The blend 109-144' F. from the West Virginia natural gasoline gave the greatest increase in octane number for 1 cc. of tetraethyllead and also comprised the greatest percentage of the charge. Since this material is known to contain largely 2-methylpentane, the lead susceptibility of the latter was obtained and its octane number was found to increase 18 upon the addition of 1 cc. of tetraethyllead. The addition of 2 cc. of tetraethyllead to the 109-144" F. blend from the West Virginia gasoline gave an octane number of approximately 98. In order to make the sample knock, it was necessary to open the throttle to maximum knock and then advance the spark to 17". The gasoline was rated directly against the primary standards. The effect of the second cubic centimeter of tetraethyllead is much smaller in comparison to the first. The data in Table I11 show clearly that octane number and lead susceptibility are not dependent alone on the boiling range of the fraction. Fractions of the same boiling range
VOLUME PER CENT ANILINE ADDED FIGURE
1, EFFECTIVENESS OF TETRAETHYLLEAD AND ANILINE IN PENXSYLVAA-IA STRAIGHT-RUN GASOLINE
INDUSTRIAL AND ENGINEERING CHEMISTRY
7 94
VOL. 2 8 , NO. 7
OF GASOLINE FRACTIONS 'ro TETRAETHYLLEAD AND ANILISE TABLE 111. SUSCEPTIBILITY
Octane No-. Blend 1 cc. Original T. E. L./ blend gal.
+
Gasoline Fractionated
Boiling Range of Blend
Vol % of Charge
Blend
+
aiipne
Octane No. Increase Lead Aniline blend blend
Compounds Piohably Piesent
OF
W. Va. natural Bradford straight-run Mich. naphthaa Yates straight-run
109-144 97-142 115-145 97-145
10.0 3.7 3.5 3.1
73 72 78 78
91 82 92 85
79 76 80 79
18 10 14 7
6 4 2 1
Cyclopentane and isomeric hexancs
W. Va. natural Bradford straight-run Mich. naphthaa Yates straight-run
160-189 165-189 160-181 162-192
5.5 2.0 4.4 3.8
81 79 79 79
90 86 90 88
84 82 83 82
9 7 11 9
3 3 4 3
Cyclohexane, benzene, and isomeric heptanes
W. T7a. natural Bradford straight-run Mich. naphthaa Yates straight-run
213-233 213-236 212-235 211-237
5.2 5.3 6.2 5.6
72 72 75 74
82 82 86 82
76 76 80 77
10 10 11 8
4
4 5 3
Methylcyclohexane, toluene, and isomeric octanes
Bradford straight-run A Yates straight-run
270-283 273-284 274-283
4 1 6.0 4.8
72 76 66
83 86 73
77 79 70
11 10 7
5 3 4
Ethylbenzene, xylenes, meric nonanes
Bradford straight-run A Yates straight-run a 1 1 1 O t o 274' F.
312-333 318-333 3 19-338
6 3 3.9 8.2
52 56 53
60 61 59
56 56
8 5 6
4 0 5
9 carbon aromatics and naphthenes, and isomeric decanes
and Buell (79,it is possible that some, but not all, of thevariations in lead susceptibility are due to sulfur compounds. The effect of differences in hydrocarbon structure in these fractions should not be overlooked. For comparative purposes the octane numbers of certain compounds and blends are given in Table IV. The responsiveness of n-hexane to tetraethyllead is of interest and is in agreement with the high lead susceptibility of the Michigan naphtha. The fact that a gasoline or naphtha has a low octane number does not necessarily preclude its use as a motor fuel if its responsiveness to tetraethyllead is good. TABLE IV. OCTANENUMBERSOF COMPOUNDS AND BLEKDS No. Procedure 345-Blend 1 cc. Blend 2 cc. Original T. E. L./ blend gal. T. E. L./gal. .---Octane
Fuel Cyclohexane 2-Methylpentane 3-Methd~entane n-Hexane W. Va. natural blend Blend A Yates blend Yates blend Yates blend
Boiliug Range of Blend F.
..... ..... ..... .....
109-144 273-284 97-145 211-237 274-283
83 70 66 22 73 76 78 74 66
+
88 87 83 54 91 86 85 82 73
+
.. ,.
58
These blends from fractionated gasolines could probably satisfy most of the requirements of aviation fuels, such as stability, gum formation, octane number, concentration of tetraethyllead, sulfur content, constancy of octane number under various operating conditions, and availability.
Addition of Aniline to Gasolines Containing Tetraethyllead Although aniline has been known as a good antiknock material for some time, it is not being used today commercially as an antiknock. Nevertheless it has properties that other
iso-
antiknocks do not have. The addition of aniline up to 7 volume per cent gives practically a linear increase in octane number for straight-run gasolines, whereas tetraethyllead, for example, gives only small increases in octane number when over 2-3 cc. are used. In cracked gasoline aniline gives a greater increase in octane number for the first 2 per cent than it does for the second 2 per cent, but from 2 to 7 per cent the increase is again practically linear. This property of aniline points to the possibility that it might supplement the action of tetraethyllead by acting independently of it. In Figure 1 the effect of adding aniline to a straight-run gasoline and to the same gasoline containing 1 cc. of tetraethyllead per gallon is shown. The slopes of the aniline-gasoline and aniline-tetraethyllead-gasoline curves are about the same. In other words, the tetraethyllead and the aniline are acting independently of one another. Certain cracked gasolines behave similarly and can be easily brought up to 80 octane number or higher by the use of aniline and tetraethyllead together, whereas the use of tetraethyllead alone would fail to accomplish this result.
QS (approx.)
89 92 84 79
and
Literature Cited (1) Alden, R . C., Natl. Petroleum News, 24, 32 (1932).
(2) Campbell, J. M., Signaigo, F. K., Lovell, W. G., and Boyd, T. A., IND.ENG.CKEM.,27, 593 (1935). (3) Garner, F. H., and Evans, E. G., J . Inst. Petroleum Tech., 18, 751 (1932). (4) Hebl, L. E., and Rendel, T. B., Ibid., 18, 187 (1932). (5) Hebl, L. E., Rendel, T. E., and Garton, F. L., IND. ENG. CHEM.,25, 187 (1933). (6) Leslie, R. T., and White, J. D., B u r . Standards J . Research, 15, 211 (1935).
( 7 ) Schulze, W. A,, and Buell, A. E., Natl. Petroleum News, 27, 2 5 (1935).
(8) Tongberg, C . O., and Fenske, M. R., IND.EXG.CHEM.., 24, 814 (1932). (9) Tongberg, C. O., Quiggle, D., and Feiske, 201 (1936).
RBCEIVED April 6, 1936.
LM. R.. Ibid., 28,
