HYDROOEN CYANIDE
1. 2.
3. 4. 5.
6. 7. FLUORINE -OXYGEN F L O W SYSTEM
8.
Fluorine-oxygen cylinder Pressure gage 0(Monel), 1 6 0 pounds per square inch absolute Sulfuric acid constant pressure bub bier Mercury manometer Kel-F oil flowmeter Teflon orifice Fluorine-oxygen outlet Hydrogen cyanide cylinder
9. Water pump 10. Pressure gage, 0-60 pounds per square inch absolute in 11. Flowrator water bath 12. Knife heater 13. Stirrer 14. Thermoregulator 15. Water bath 16. Thermoregulator relay 17. Hydrogen cya*nideoutlet ' 18. Valve, Monel or stainless steel for thorine service
F L O W SYSTEM
Gas streams are penetrated in these two flow systems
CHARLES S. STOKES and A. V. GROSSE, Jr. The Research Institute of Temple University, Philadelphia 44, Pa.
Hydrogen Cyanide-Fluorine-Oxygen Flame Dual gas streams burned in a diffusion torch produce the highest temperatures that can be achieved with commercially available materials *
f
T E M P E R A T U R E S above 4000' K. have been produced in this laboratory by burning hydrogen with fluorine (8, 9 ) and cyanogen with oxygen (3, 4 ) . Cyanogen, however, is not commercially available, and fluorine is expensive. As these flames produce temperatures over 4000' K . and carbon monoxide, nitrogen, and hydrogen fluoride as combustion products, which are stable a t these high temperatures, it was assumed that if cheap compounds could be burned to such products, an inexpensive source of high intensity heat could be produced. The heat release would be enhanced if highly endothermic compounds were burned, as their heat of formation would add to the heat of combustion. Hydrogen cyanide and acetylene are such compounds. Hydrogen cyanide, fluorine, and oxygen are available in quantity, and a flame with these constituents produces a temperature of approximately 4000' K. As fluorine is by far the most costly material, the hydrogen cyanide-oxygenfluorine flame produces about 1.9 times
the amount of heat with approximately the same temperature as the hydrogen and fluorine flame for the same cost:
+ F B 2HF + 128 kcal. (1 atm., 25" C.) 2HCN + + Fz 2HF + 2CO + NB + 243.63 kcal. (1 atm., 2 5 " C . ) H2
-+
0
2
-+
The first objective in studying the hydrogen cyanide-oxygen-fluorine flame, therefore, was to establish its stoichiometry, so that theoretical flame temperatures could be calculated.
Stoichiometry of Flame Reaction Materials. The fluorine was obtained in cylinders from the Pennsylvania Salt Mfg. Co. I t was mixed with oxygen in a small pressure cylinder which was allowed to fluorinate prior to use. Fluorine was admitted to the cylinder to 50 pounds per square inch absolute, followed by oxygen to 100 pounds per square inch absolute. The mixture was allowed to diffuse for at least a day before use.
The hydrogen cyanide, obtained from the American Cyanamid Co., contained 2 to 3y0 water with small amounts of phosphoric acid as an additive inhibitor. As these impurities would lower the flame temperature, it was desirable to purify the cyanide by two distillations in vacuo. Small amounts of the liquid were transferred from the main cylinder into a trap containing a drying agent at dry ice temperature and then distilled from the trap to a small evacuated cylinder used for the runs. Apparatus. The hydrogen cyanide was brought to 2-atm. pressure by heating the cylinder in a constant temperature bath at 47' C. The oxygen-fluorine mixture was admitted from the pressure cylinder through a constant pressure sulfuric acid bubbler, copper or Kel-F connections being used throughout. The two streams were burned in a diffusion torch. The oxygen-fluorine mixture went through a 0.5-mm. stainless steel tube which was surrounded by a VOL. 49, NO. 8
AUGUST 1957
13 1 1
Table I.
Data from Two Runs
OxygenFluorine
iMixtureFz,
Tol. Gas Collected
0 2 ,
$&
%
FdOz Ratio
48 56
52
0.925
44
1.27
1701.
vol.
COa
CO,
Mole %
Mole %
N.T.P., Cc.
