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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 C H E M I ST K Y
The carbon dioxide in the product could be scrubbed out with triethanolamine and recovered. Losses of carbon dioxide due t o carbon monoxide formation could be readily made up from the flue gases of the heating operation. In this fashion a gas containing about 10 per cent of unsaturates (mainly acetylene), 10 per cent carbon monoxide, 35 per cent hydrogen, and 45 per cent methane could be obtained. The acetylene can be profitably converted into a variety of products for which there are large markets. Thus it is possible to make acetaldehyde, acetic acid, benzene, chloroprene, etc. Additional outlets for acetylene could be provided by hydrogenating it to ethylene. The latter could, for example, be used as the raw material for the production of ethyl alcohol, formaldehyde, ethylene glycol, and/or lubricating oil. By using a longer time of contact of the carbon dioxidemethane mixture, a product can be obtained which contains little or no methane, being mainly a mixture of hydrogen, carbon monoxide, and acetylene. After removal of the acetylene by an appropriate absorption medium, the remainder of the gas could be used for the production of methanol and higher alcohols, or for the production of synthetic motor fuel
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by passage over the catalyst's developed hy Fixher (1) and by Smith ( 7 ) . The influence of dilution with carbon dioxide on the pyrolysis of hydrocarbons such as ethane, propane, butane, etc., is a t present under investigation in this laboratory. LITERATURE CITED (1) E'i,*cher a n d Peters, Brennst0.f-Chem., 12, 286 (1931). (21 Fischer a n d Pichler, Ibid., 13, 381 (1932). ( 3 ) H a v k , Golden, Storch, a n d Fieldner, IBD. ESG. CHEW, 24, 28 (1932). (4) I m p e r i c a l C h e m . I n d . a n d D. Binnie, English P a t e n t 343,881 (SO\,. 1 2 , 1929). (5, Kassel, J . Am. Chem. Soc., 54, 3949 (1932). (6) R u d d e r a n d B i e d e r m a n n , BuU. SOC. chim., 47, 710 (1930). EXQ.CHEM.,20, 1341 (1928). (7) S m i t h , H a w k , a n d R e y n o l d s , IND. ( 8 ) Storch, B u r . Mines, Circ. 6549 (1932). (9) Storch, J . d m . Chem. Soc., 54, 4188 (1932). (101 Storch a n d G o l d e n , I h i d . , 54, 4662 (1932).
RECEIVED January 7, 1933. Presented before the Division of Industrial and Engineering Chemistry a t the 85th Meeting of the American Chemical Society, Washington, D . C . , March 26 t o 31, 1933. Published hy permission of the Director, U . S. Bureau of Mines. (Not subject to copyright.)
Explosive Properties of Propylene Dichloride-Air Mixtures G.
D
w. JOKES,Mr. E. MILLER,AND H. SEARIAX, Bureau of %lines Experiment Station, Pittsburgh, Pa.
U R I S G the past few years many new combustible
compounds have been marketed by manufacturers for various uses. Propylene dichloride, heretofore a rather expensive compound, may now be manufactured from cheaper sources of propylene a t a cost low enough to compete with other substances as a solvent for oils and greases. This makes it desirable that the fire and explosion hazard attending its use be ascertained. The empiric formula of propylene dichloride is C3H6C12 which is the same as that representing the four known dichloropropanes with which it is isometric. The constitutional formula of propylene dichloride is CH3 ('HCI CH2C1, and this same structural formula represents that one of the dichloropropanes that is also styled dichloroethylmethane. The four dichloropropanes differ from each other in their fundamental characteristics and particularly in their boiling points. The propylene dichloride now being produced commercially has a boiling point of 96.8" C. I n order t h a t this material may be used safely, it mas decided to determine its limits of inflammability when mixed with various proportions of air, the pressures which might be developed when these mixtures are ignited in a closed chamber, and how easily the mixtures are ignited.
PURITY OF PROPYLENE DICHLORIDE The propylene dichloride, supplied by the ('arbide and Carbon Chemicals Corporation, conformed to the following specifications : Specific gravity, 20°/200 Weight per gallon. Ib. Acidity, yo Boiling range: Below 93' (199.4' F.) Below 99' C. (210.2° F.i Above 103' C. (217.4' F.) Water
1.159 9.64 Not more than 0.005
Sone Not less than 95 None Substantially anhydrous
Tests were made with the propylene dichloride as received after it had been treated with anhydrous sodium sulfate to remove any traces of water which might be present.
TESTAPPARATUS The lower limit of inflammability in air was determined in an 8-liter closed cylindrical bomb. The bomb was 4 inches in diameter and 38 inches long, and mas mounted in a vertical direction. Flames were initiated near the bottom of the bomb and propagated in an upward direction. This bomb is now used as standard equipment for the determination of the limits of inflammabihy of gases and vapors. The bomb was designed and used in an investigation to determine the explosive properties of acetone-air mixtures ( 2 ) . Reference is made to this report for details of operation and methods used in the preparation and analysis of the vapor-air mixtures. LOWERIKFLAMJIABLE LIhlIT
BKD PRESSURES
DEVELOPED
Table I gives the results of tests made to determine the lower inflammable limit of propylene dichloride vapor in air and the pressures developed in the closed bomb. The lower limit was found to be 3.40 per cent by volume in air. The pressures developed varied from 38 pounds per square inch (above atmospheric) a t the lower limit to 67 pounds a t the maximum, when 5.02 per cent propylene dichloride was present. The saturation point of propylene dichloride in air a t the laboratory temperature was reached when the amounts present equaled 5.63 per cent and the pressure fell to 61 pounds. Calculation shous that the ideal mixture of propylene dichloride in air, which contains just sufficient combustible to consume all the oxygen present and give complete combustion products-carbon dioxide, water vapor, and hydrochloric
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Vol. 25, No. 7
FIGURE 1. APPARATUS FOR DETERMINING LIMITS OF INFLAMMABILITY OF VAPORS
acid-should contain 4.95 per cent propylene dichloride by volume. The results show that the maximum pressure is produced when the amount present is slightly on the rich side (5.02 per cent). TABLE I. PRESSURES PRODTJCED BY P R O P Y L E X E DICHLORIDEAIR MIXTURES,AXD TESTS MADETO ESTABLISHLOWER INFLAMMABLE LIMIT (Temperatures, 24' t o 28.4'
c.mm. (75.2' to 83.1' mercury]
F.): pressure8,735.8 to740.0
PRESSURE WHEN PRODUCED
TEST 20 22 21 23 19 18 17 16 11 12 10 9 8 7 6 4 3 2
PROPYLEKEIGNITED ABOVE
DICHLORIDE 70b y vol. 3.36 3.39 3.41 3.39 3.48 3.59 3.68 3.79 3.93 3.96 4.15 4.44 4.58 4.74 5.02 5.31 5.57 5.63
ATMOPRERIC Lb.jsg. in.
..
.. ..
38 41 44 50 50 50 51 56
58 60 66 67 66 65 61
PROPAQATED
FLAME NO NO
NO Yes Yes Yes Yes Yes Yes Y es Yes Yes Yes Yes Yes Yes Yes Yee
The pressures produced by combustible mixtures when ignited in a closed bomb have an indefinite meaning unless the comparisons are made in the same apparatus. The pressures produced by a given combustible mixture will vary when tested in different apparatus, depending upon the size and shape of the apparatus. However, the pressures become of real significance when comparing the pressures produced by different combustible mixtures in the same apparatus. The cylindrical bomb used in this investigation has been used to determine the maximum pressure developed by several com-
bustible gases and vapors in air, and the following values for the maximum pressures have been obtained: COMBUS-COMBUS-
COMBUSTIBLE Methane Propylene dichloride Aretnnr . .. .. . Manufactured
AfAX.
TIBLE I N
TIBLE
4.95 4.95
5.0 5.5
67 78
561
18.40 9.45
20.5 10.5
93 106
568 498
AIR FOR PRESENT PRESCOMPLETE A T h f A X . EURE LIMITSOF INFLAMMABILITY COMBCS- PRES- DEYEL-IGNITION Lower Upper TION SURE OPED TEMP. % Lb./sq. in. C. % b y volume 70 4.90 15.0 9.45 9.8 66 645 3.40 2.55
14.5 12.8
gas" 6.50 36.0 Methyl formate 5.05 22.7 a Composition of manufactured gas: % b y vol. Carbon dioxide 2.2 Illuminants 4.1 2.0 Oxygen Hydrogen 45.0
557
% by Carbon monoxide Methane Ethane Nitrogen
23.3 10.7 1.4 11.3
The above tests show that propylene dichloride exploded in a closed bomb gives a maximum pressure which is comparable to that produced by methane-air mixtures and which is less than the pressure produced by acetone, manufactured gas, and methyl formate.
July, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
UPPER IXFLAMMABLE LIMITOF PROPYLENE DICHLORIDE-AIR MIXTURES Propylene dichloride has insufficient vapor pressure to give upper limit mixtures at laboratory temperatures. Upper limit tests were therefore made in a n apparatus (Figure 1) having a n explosion tube 2.5 inches in diameter and 3 feet long. The method of preparing the propylene dichlorideair mixtures follows that described by Jones and Klick ( 3 ) . The vaporizer, 0 , the copper tube, p , leading from the vaporizer to the glass explosion tube, and the explosion tube itself were wrapped with nichrome resistance wire, and sufficient current was passed through the wire to maintain the temperature in the glass explosion tube at 100-105° C. I n these tests the inflammable mixtures were ignited by electrodes 4 inches from the closed end, and the flame mas propagated upward from the closed to the open end. The mixtures were also in motion when ignited and were traveling forward
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There are listed in the following table the inflammable limits in air of several chlorohydrocarbons showing the effect of addition of chlorine to the molecule. These values were obtained in the explosive research laboratories, Pittsburgh Experiment Station, U. S. Bureau of Mines: INFLAMMABLE
COMBUBTIBLE Methane iMethyl chloride Methylene dichloride Chlorbform Carbon tetrachloride
Propane Propyl ohlbride Propylene dichloride
FORMUL~
Lower
LIMITS Upper
Per cent b y colume 15.00 5.00 18.70 5.2 N o t explosive
h o t explosive Not explosive 12,50 3.10 1 4 . SO 4.00 21.70 4.00 15.90 6.20 12.80 9.70 Not explosive 9.50 2.40
CONCLUSIOKS
PROPYLENEB1CIIMP.W PPRCENTBYVOLUM:
FIGURE2. IGNITION TEMPERATURES OF PROPYLENE DICHLORIDE-AIR MIXTURES
through the tube a t a rate of about 0.5 cm. per second. Tests have shown t h a t the limits are slightly wider under these conditions than when the mixtures are not in motion. The upper limit of inflammability at 100" C. was found to be 14.5 per cent in this apparatus.
The lower inflammable limit of propylene dichloride in dry air a t laboratory temperatures and pressures was found to be 3.40 per cent by volume. The upper inflammable limit of propylene dichloride in dry air a t 100" C. and normal pressures was found to be 14.5 per cent by volume. The maximum pressures developed by propylene dichloride-air mixtures in a n 8-liter @.&quart) closed cylindrical bomb 4 inches in diameter and 38 inches long was found to be 67 pounds per square inch above atmospheric. This maximum pressure was produced with mixtures containing 5.02 per cent propylene dichloride. The mixture which contains the proper amount of propylene dichloride just to consume all the oxygen present contains 4.95 per cent; therefore, the maximum pressure is produced by mixtures containing propylene dichloride slightly in excess of that necessary for complete combustion. A comparison of the maximum pressures developed by propylene dichloride-air mixtures in the closed bomb with values obtained in the bomb with other combustibles, shows that the maximum pressures developed by propylene dichloride-air mixtures are slightly more than that produced by methane-air mixtures and considerably less than those produced by acetone, manufactured gas, and methyl formate. The ignition temperatures of propylene dichloride-air mixtures show that this combustible has ignition temperatures varying from 557" to 570" C. These values are lower than those obtained for methane, nearly the same as those for acetone and manufactured gas, and higher than that for methyl formate.
IGNITIOX TEMPERATURE The ignition temperature of propylene dichlorideair mixtures was determined in an apparatus similar to that used by Mason and Wheeler (4). It consisted of a transparent quartz bulb of 88 cc. capacity, mounted in a n electric furnace in which the temperature could be accurately controlled (1). Since the ignition temperature of combustibles varies with the concentration of the combustible present, the time the mixture is in contact with the heated surface, the initial pressure of the mixture, the concentration of the oxygen present, the type of apparatus used, the material of which the apparatus is constructed, and other variables, it, is apparent that data given for the ignition temperature are of little value for comparing different combustibles unless all tests are made under the same conditions. The data given in this report for different combustibles were made with the same apparatus under the same conditions. The ignition temperatures obtained for propylene dichloride-air mixtures are given in Figure 2 . The ignition temperature varies only slightly with the concentration of propylene dichloride present in the mixture. The lowest ignition temperature found was 557" C. For comparison, the ignition temperatures obtained for other combustibles in the same apparatus are given in Table I.
RECEIVED December 12, 1932. Published b y permiasion of the Director, U . S. Bureau of Mines. ( N o t subject t o copyright.)
GERM.4N POTASH COUNCIL REORGANIZED. In order to give new impulse to national economy, the Reich Government has ordered a reorganization of both the Coal and Potash Councils. The reorganization of the former will be of a more comprehensive nature than that of the potash, the chief changes in the latter for the present being a realignment in its membership with an increased representation for agriculture.
The Potash Council comprises 30 members representing the various national interests concerned, and while, under the reorganization, the total number of members will remain unchanged, members representing agriculture will be increased from four t o seven, with a corresponding decrease for workers in the potash industry. Members representing the potash workers must be engaged in productive activity.
LITERATURE CITED (1) Coward, H. F., Jones, G. TT., Dunkle, C. G., and Hess, B. E., Bur. Mines and Carnegie Inst. Tech., C'doperatice Bull. 30, 34 (1926). ( 2 ) Jones, G. W., Harris, E. S., and Miller, W. E., Bur. Mines, Tech. P a p e r 544 (1932). ( 3 ) Jones, G. W., and Klick, J. R., IND.ENO.CHEM., 21, 791 (1929). (4) Mason, T. N.,and Wheeler, R. V., J . ?hem, Soc., 121, 2079 (1922).
