Pure Ozone Flame and the Combustion of Various Fuel Gases in Pure

Pure Ozone Flame and the Combustion of Various Fuel Gases in Pure Ozone A. G. STRENG and Α. V. GROSSE

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on February 3, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch006

The Research Institute of Temple University, Philadelphia 44, Pa.

The interest in studies of pure ozone, solid or liquid, in explosives lies not only in the momentary production of high temperatures, but primarily in the possibility of determining experimentally the parameters for equations of state for simple molecules in a region of pressures (about 100,000 atm.) a n d temperatures ( 5 0 0 0 ° to over 10,000° K.) far outside of that which can be investigated by any ordinary method.

In t h e l a s t f e w y e a r s t h i s i n s t i t u t e h a s b e e n p a r t i c u l a r l y i n t e r e s t e d i n t h e p r o d u c t i o n of h i g h t e m p e r a t u r e s b y c h e m i c a l m e t h o d s . T h e t w o p r e r e q u i s i t e s f o r p r o d u c i n g h i g h t e m p e r a t u r e s a r e : a r e a c t i o n w i t h a h i g h h e a t release, a n d t h e r m a l s t a b i l i t y o f the reaction products. C a r b o n monoxide a n d nitrogen are t h e r m a l l y t h e m o s t stable molecules k n o w n . B y b u r n i n g c y a n o g e n w i t h o x y g e n t o these p r o d u c t s a t 1 a t m . a t e m p e r a t u r e of 4 8 0 0 ° K . w a s p r o d u c e d (2). B y c a r r y i n g out t h e same combustion under pressure 5 0 5 0 ° K . h a s b e e n a t t a i n e d (1). B y u s i n g a m o r e e n d o t h e r m i c c o m p o u n d , s u c h as c a r b o n s u b n i t r i d e , o r C N , a t e m p e r a t u r e o f 5260° K . h a s b e e n r e a c h e d (5). B y c o m b i n i n g t h e a b o v e e n d o t h e r m i c fuels w i t h a n e n d o t h e r m i c o x i d i z e r , s t i l l h i g h e r t e m p e r a t u r e s s h o u l d b e a t t a i n a b l e . B e c a u s e ozone i s a n o b v i o u s s u b s t i t u t e f o r o x y g e n , c o m b u s t i o n s w i t h ozone w e r e s t u d i e d . 4

2

O z o n e i s one of t h e m o s t s e n s i t i v e c o m p o u n d s k n o w n a n d a t h i g h c o n c e n t r a t i o n s is p r o n e t o e x p l o s i o n s o r d e t o n a t i o n s . F o r t h i s r e a s o n t h e d e c o m p o s i t i o n o r " c o m b u s t i o n " f l a m e of ozone t o o x y g e n w a s first s t u d i e d . T h e h e a t of c o m b u s t i o n of ozone t o m o l e c u l a r o x y g e n o r Δ H° a t 2 9 1 ° K . = —33.92 k c a l . p e r m o l e . I n v i e w of t h i s h i g h heat l i b e r a t i o n i t was expected t h a t p u r e ozone c o u l d be b u r n e d t o oxygen i n a v i s i b l e flame, i f i t s e x p l o s i o n o r d e t o n a t i o n c o u l d b e a v o i d e d . Ozone-oxygen m i x t u r e s a n d e v e n p u r e ozone c a n b e b u r n e d i n a r e g u l a r flame t o o x y g e n w i t h o u t m i s h a p , i f t h e ozone u s e d i s p u r e a n d free f r o m s e n s i t i z e r s . T h e o z o n e w a s p u r i f i e d b y t h e m e t h o d first d e s c r i b e d b y T h o r p , A r m o u r R e s e a r c h F o u n d a t i o n ( 7 ) . T h e e x p e r i m e n t a l p r o c e d u r e h a s b e e n d e s c r i b e d i n d e t a i l b y S t r e n g a n d G r o s s e (6). f

P u r e ozone b u r n s t o o x y g e n w i t h a b l u e flame w i t h a t y p i c a l p i n k c a s t . T h e l u m i n o s i t y of t h e flame i s l o w , a l t h o u g h i t s t e m p e r a t u r e i s 2 6 7 7 ° K . f o r 1 0 0 % ozone a t 1 - a t m . p r e s s u r e a n d 300° K . i n i t i a l t e m p e r a t u r e . T h e e x p e r i m e n t a l l y d e t e r m i n e d b u r n i n g v e l o c i t y u n d e r t h e same c o n d i t i o n s i s 4 7 5 c m . p e r s e c o n d . T h e p u r e o z o n e flame i s of p a r t i c u l a r t h e o r e t i c a l i n t e r e s t , because i t r e p r e s e n t s t h e s i m p l e s t flame i m a g i n a b l e . T h e o n l y p o s s i b l e i n t e r m e d i a t e s b e t w e e n t h e i n i t i a l a n d final p r o d u c t s a r e o x y g e n a t o m s . T . v o n K a r m a n , J . O . H i r s c h f e l d e r , a n d t h e i r 38

In OZONE CHEMISTRY AND TECHNOLOGY; Advances in Chemistry; American Chemical Society: Washington, DC, 1959.

STRENG A N D

39

GROSSE-PURE O Z O N E FLAME

associates a n d R . S a n d r i h a v e d e v e l o p e d t h e t h e o r y of l a m i n a r flame p r o p a g a t i o n . R e c e n t l y t h i s t h e o r y was a p p l i e d b y v o n K a r m a n w h e n c a l c u l a t i n g t h e t h e o r e t i c a l flame v e l o c i t y f o r 1 0 0 % ozone. H i s r e s u l t s (8) are e s s e n t i a l l y i n a g r e e m e n t w i t h t h e authors' experimental results. T h e theories give a detailed insight i n t o the m e c h a n i s m a n d k i n e t i c s of t h e flame p r o p a g a t i o n . T e m p e r a t u r e Effect o n

Burning Velocity of

Ozone

S u b s e q u e n t t o t h e Y a l e p r e s e n t a t i o n {6) t h e b u r n i n g v e l o c i t y of p u r e ozone w a s also d e t e r m i n e d a t — 7 8 ° C . a n d f o u n d t o e q u a l 270 c m . p e r s e c o n d . I n first a p p r o x i m a t i o n t h e b u r n i n g v e l o c i t y of ozone is a s t r a i g h t - l i n e f u n c t i o n of t e m p e r a t u r e .


}

Extrapolated Velocities °C.

°K. 273 233 161

0 -50 -112 a

a

D i f f u s i o n F l a m e s of

Cm./Sec. 420 325 205

Boiling point of ozone.

Pure O z o n e with

Fuel

Gases

P u r e ozone w a s s u c c e s s f u l l y b u r n e d , i n a d i f f u s i o n flame, w i t h h y d r o g e n , c a r b o n m o n o x i d e , c y a n o g e n , m e t h a n e , a n d e t h y l e n e . T h e ozone was a d m i t t e d a t t h e r a t e of ^ 6 cc. p e r s e c o n d t h r o u g h t h e i n n e r t u b e of a n a l u m i n u m b u r n e r ( t i p a r e a 0.34 s q . m m . ) , w h i l e t h e f u e l gases w e r e a d m i t t e d t h r o u g h a n a n n u l u s w i t h a n a r e a of 1.42 s q . m m . , u s u a l l y i n q u a n t i t i e s sufficient f o r c o m p l e t e c o m b u s t i o n . D e t a i l s of t h e b u r n i n g t i p a r e g i v e n i n F i g u r e 1. C o m p a r a t i v e r u n s were m a d e w i t h t h e s a m e a m o u n t of o x y g e n . O z o n e b u r n s i n h y d r o g e n s i m i l a r l y t o o x y g e n , t h e o n l y difference b e i n g t h a t t h e ozone flame is s l i g h t l y b r i g h t e r . T h e ozone was a d m i t t e d first a n d h y d r o g e n a d d e d subsequently. I n c a r b o n m o n o x i d e ozone b u r n s w i t h a m u c h b r i g h t e r flame t h a n o x y g e n . The c a r b o n m o n o x i d e w a s i g n i t e d first, t h e n ozone w a s a d m i t t e d . P h o t o g r a p h s of t h i s flame a r e s h o w n i n F i g u r e 2, C o m p a r e d w i t h t h e c a r b o n m o n o x i d e - o x y g e n a n d p u r e ozone flame. O z o n e b u r n s i n c y a n o g e n w i t h t h e b r i g h t e s t flame p r o d u c e d so f a r i n these l a b o r a t o r i e s ( F i g u r e 3 ) . T h e flame t e m p e r a t u r e is c a l c u l a t e d to be 5200° K . — i . e . , p r a c t i c a l l y i d e n t i c a l t o t h a t of t h e C N - 0 flame {3). I n t h i s case t h e ozone flame was e s t a b l i s h e d first a n d t h e n t h e c y a n o g e n w a s a d d e d . M e t h a n e a n d e t h y l e n e , r e s p e c t i v e l y , were i g n i t e d first a n d t h e n ozone w a s a d d e d . B o t h flames w e r e a g a i n b r i g h t e r t h a n t h e c o r r e s p o n d i n g o x y g e n flames. 4

Self-Igniting

P r o p e r t i e s of

2

2

Ozone—Fuel

Gas

Mixtures

S p e c i a l tests w e r e m a d e t o d e t e r m i n e t h e s e l f - i g n i t i n g c h a r a c t e r i s t i c s of t h e f u e l g a s ozone m i x t u r e s . A t atmospheric pressure, w h e n the m i x t u r e was a d m i t t e d t h r o u g h the a l u m i n u m t i p , n o i g n i t i o n t o o k p l a c e w i t h h y d r o g e n , c y a n o g e n , a n d m e t h a n e (ozone r a t e 6 cc. per second). C a r b o n monoxide a n d ethylene, however, ignited spontaneously a n d b u r n e d n o r m a l l y a f t e r w a r d s w i t h o u t i n i t i a t i n g a n e x p l o s i o n o r d e t o n a t i o n i n t h e ozone line. Static B e h a v i o r of

100%

Ozone—Fuel

Gas

Mixtures

T h e p r e c e d i n g r e s u l t s i n d i c a t e d t h a t m i x i n g 1 0 0 % ozone w i t h h y d r o g e n , c y a n o g e n , a n d m e t h a n e is possible, e v e n i f f o r a v e r y s h o r t t i m e . T h i s l e d t o tests of m i x i n g 1 0 0 % ozone w i t h h y d r o g e n , c y a n o g e n , a n d m e t h a n e , r e s p e c t i v e l y . T h e m i x e d gases


40

A D V A N C E S IN


9.53 mm!

CHEMISTRY SERIES

W)

TOP VIEW ( TIP ONLY)

Figure 1.

Burner tip for ozone diffusion flames

were a l l o w e d t o s t a n d i n b o r o s i l i c a t e glass t u b e s ( P y r e x b r a n d N o . 7740) of a b o u t 10 cc. v o l u m e . T h e c o n d i t i o n s u s e d a n d o b s e r v a t i o n s m a d e are g i v e n i n T a b l e I . T a b l e I.

Mixture 4 H + Os 4H + 0 I.5C2N2 + 0 I.5C2N2 + O3 1.5CH4 + 20 1.5CH4 + 20 2

2

3

3

3 3

Behavior of Various Fuel G a s e s with Pure O z o n e

Total Pressure, M m . Hg 504 504 774 551 778 804

Temp., °C. -78 +21 0 + 23 -78 + 21

Time of Standing, Hours

Results

*4 η 1 2 q j

No change in pressure. No visible reaction

18 1.0 1.0

Pressure increased 6 mm. No change in pressure. Pressure increased 26 mm.

A l l t h r e e m i x t u r e s are s t a b l e f o r h o u r s , a t least a t d r y ice t e m p e r a t u r e s . M e t h a n e reacts n o t i c e a b l y a t r o o m t e m p e r a t u r e , w h i l e h y d r o g e n a n d c y a n o g e n cause n o c h a n g e i n p r e s s u r e . T h e b l u e c o l o r of ozone c o u l d be o b s e r v e d a f t e r a l l these tests. O n i m m e r s i n g t h e c y a n o g e n - o z o n e t u b e i n l i q u i d o x y g e n , s o l i d c y a n o g e n a n d b l u e l i q u i d ozone c o n d e n s e d a f t e r t h e t e s t ; o n i m m e r s i n g t h e s a m e t u b e i n a d r y ice b a t h , t h e u n r e a c t e d c y a n o g e n w a s s o l i d i f i e d a n d t h e u n r e a c t e d ozone gas p u m p e d off.



STRENG AND GROSSE-PURE OZONE FLAME

Figure 2.

Ozone

flames

burning

at 6 cc. per second

A. Combustion of 1 0 0 % ozone, 6 cc. per second, to oxygen B. Combustion of 1 0 0 % ozone, 6 cc. per second, in excess of carbon monoxide C. Combustion of pure oxygen, 6 cc. per second, in excess of carbon monoxide

Figure 3.

O z o n e flames burning at 6 cc. per second

A. Combustion of 1 0 0 % ozone, 6 cc. per second, to oxygen B. Combustion of 1 0 0 % ozone, 6 cc. per second, in excess of cyanogen (temperature of flame 5200* C. Combustion of pure oxygen, 6 cc. per second, in excess of cyanogen


A D V A N C E S IN CHEMISTRY SERIES

42

Premixed Cyanogen-Ozone Flames In view of the surprizing stability of cyanogen-ozone mixtures, the gases were burned i n long tubes 1.6 m m . i n inside diameter, without detonation, at room temperature and atmospheric pressure. I n wider tubes, as expected, the mixtures exploded, shattering the tubes completely. T h e stoichiometric cyanogen-ozone mixture (1.5 C N + 0 ) burns very rapidly with a very bright flame b u t without explosion or detonation. T h e corresponding mixture of cyanogen and oxygen burns rapidly under the same conditions, although more slowly, and the flame is definitely less bright than the flame with ozone. Pure ozone under the same conditions burns with a fallow flame, again without explosion or detonation. In view of the fact that the same mixtures of cyanogen-oxygen and pure ozone itself can be burned from burner tips at a steady flame at a constant rate, it is likely that ozone-cyanogen mixtures can also be successfully burned i n the same manner.


2

Production of Instantaneous

2

3

High Temperatures

T h e demonstrated possibility of premixing various fuels with pure ozone opens up new opportunities for using pure ozone i n the study of explosives. In connection with the above investigation, it has been found that liquid ozone is stable i n the presence of cyanogen powder at 9 0 ° K . B y evaporating liquid ozone i n a vacuum it can be solidified i n the form of ozone crystals on crystals of cyanogen without explosion. Careful handling should make it possible to study the detonation of various mixtures of solid cyanogen powder with either liquid ozone or solid ozone powder at various loading densities. Whereas in the gaseous cyanogen-ozone system the highest temperatures are produced when the products of combustion are carbon monoxide and nitrogen, simple application of the hydrodynamic theory of detonation shows that higher temperatures—i.e., up to and even above 10,000° K . — w o u l d be reached for the stoichiometric equation : ( C N ) + 4/3 0 -> 2 C 0 2

3

2

+ N

2

because at the very high pressures of a detonation wave i n a condensed explosive (of the order of 100,000 atm.) the dissociation of the carbon dioxide molecule is negligible as compared to atmospheric pressure. Thus detonations of solid cyanogen or carbon monoxide mixtures with solid ozone (or solid oxygen) would give data for the carbon dioxide and nitrogen molecules. Detonations of solid ozone alone would give data on the oxygen molecule, etc. Techniques for handling and studying the solid cyanogen-liquid oxygen system have been developed (4).

Literature C i t e d (1) Conway, J. B., Smith, W. F. R., Liddell, W. J., Grosse, Α. V., J. Am. Chem. Soc. 77, 2026 (1955); Conway, J. B., Grosse, Α. V., Ibid., 80, 2972 (1958). (2) Conway, J. B., Wilson, R. H., Jr., Grosse, Α. V., Ibid., 75, 499 (1953). (3) Grosse, Α. V., Kirshenbaum, A. D., "Combustion of Carbon Subnitride, C N , and a Chemical Method for the Production of Continuous Temperatures in the Range of 5000-6000° Kelvin or 9000-11000° Rankine," Tech. Note 1, Contract N o . AF 18(600)1475, Study of Ultra High Temperatures, Air Research and Development Command, Washington, D . C . Dec. 15,1955. (4) Kirshenbaum, A. D., " F i n a l Report on Fundamental Studies of New Explosive Reac tions for Office of Ordnance Research," Contract N o . DA-36-034-ORD-1489, April 30, 1956, pp. 34-43. (5) Kirshenbaum, A. D., Grosse, Α. V., J. Am. Chem. Soc. 78, 2020 (1956). 4


2

STRENG A N D G R O S S E - P U R E O Z O N E

FLAME

43

(6) Streng, A. G., Grosse, Α. V., Sixth International Symposium on Combustion, Yale University, pp. 264-73, Reinhold, New York, 1956. (7) Thorp, C. E., U. S. Patent 2,700,648 (Jan. 25, 1955). (8) von Karman, T . , Sixth International Symposium on Combustion, Yale University, p. 6, Reinhold, New York, 1956. S.

RECEIVED for review March 27, 1957. Accepted June 19, 1957. Research supported by Air Force through A i r Force Office of Scientific Research, A i r Research and Development Command, under contract N o . AF 18(600)-1475.


U.


Pure Ozone Flame and the Combustion of Various Fuel Gases in Pure

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