Effect of Gaseous Diluents on Energy Yield of Ozone Generation

Effect of Gaseous Diluents on Energy Yield of Ozone Generation from Oxygen W. E. CROMWELL

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 9, 2017 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch040

The Welsbach

and T. C. MANLEY

Corp., Philadelphia,

Pa.

The effect of various diluent gases on the energy yield of ozone generation from oxygen in commercial ozonators is discussed. The greatest loss in energy yield is noted for the presence of less than 1% of hydrogen, water, or Freon 12 (dichlorodifluoromethane). Up to 50% of carbon dioxide or argon reduces the energy yield to about 85% of that expected with pure oxygen. C a r b o n monoxide or nitrogen, in amounts of less than 1 0 % , apparently increases the energy yield of ozone generation. In greater amounts, it gradually but steadily reduces the energy yield.

T h e o b j e c t of t h i s i n v e s t i g a t i o n w a s t o s t u d y ozone g e n e r a t i o n i n c o m m e r c i a l o z o n a t o r s . P r i m a r y c o n c e r n h a s b e e n p l a c e d o n o z o n a t o r s u s i n g o x y g e n feed. T h e effect of c e r t a i n f o r e i g n substances i n t h e o x y g e n has been s t u d i e d w i t h respect t o t h e e n e r g y y i e l d of ozone g e n e r a t i o n . T h e s e studies a r e c o n s i d e r e d i m p o r t a n t because ozone is a c o m p e t i t i v e c h e m i c a l . I t m u s t b e p r o d u c e d a t t h e l o w e s t possible cost. S o m e c o n t a m i n a n t s i n o x y g e n w e r e k n o w n t o decrease e n e r g y y i e l d ; o t h e r s were q u e s t i o n a b l e o r e v e n u n k n o w n . C o m m e r c i a l o z o n a t o r s m a y use e i t h e r a i r o r o x y g e n as a feed gas. A s l o n g as t h e c o m p o n e n t s of these gases a r e w i t h i n k n o w n l i m i t s , o z o n a t o r p e r f o r m a n c e c a n b e p r e d i c t e d w i t h reasonable c e r t a i n t y . R e c e n t l y , h o w e v e r , t h e size of some ozone p l a n t s h a s i n c r e a s e d t o a p o i n t w h e r e i t is e c o n o m i c a l l y feasible t o r e c y c l e t h e o x y g e n b a c k t o t h e o z o n a t o r s . T h i s m e a n s t h a t t h e o z o n e - o x y g e n m i x t u r e is p a s s e d i n t o a r e a c t i o n of some k i n d . T h e ozone is u s e d u p i n t h e process, b u t t h e o x y g e n is r e c o v e r e d f r o m t h e r e a c t i o n a n d r e t u r n e d t o t h e o z o n a t o r . I n t r i n s i c a l l y , t h i s o x y g e n w h i c h is r e t u r n e d t o t h e o z o n a t o r m a y be c o n t a m i n a t e d ; a n d t h e c o n t a m i n a n t s m a y b e m a t e r i a l s n o t normally found i n commercial oxygen. I n t h i s i n v e s t i g a t i o n , v a r i o u s d i l u e n t gases were a d d e d t o t h e o x y g e n t o see t h e i r effect o n t h e e n e r g y y i e l d of ozone g e n e r a t i o n a n d o n t h e t o t a l p r o d u c t i o n of ozone. T h e r e s u l t s i n some cases i n d i c a t e t h a t o n l y t r a c e a m o u n t s of t h e i m p u r i t y c a n be t o l e r a t e d . I n o t h e r cases, s m a l l a m o u n t s e v e n increase t h e e n e r g y y i e l d of ozone generation. P u b l i s h e d references were s t u d i e d c a r e f u l l y (1-7). U n f o r t u n a t e l y , these e a r l i e r investigations were seldom conducted i n such a w a y t h a t v a l i d comparisons c o u l d be made to present-day commercial ozonator operation. Several variables are considered i m p o r t a n t i n ozonator performance. 304

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

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F i s t h e gas flow r a t e i n p o u n d s p e r h o u r of d r y gas. W is t h e e l e c t r i c p o w e r i n w a t t s . a i s t h e e n e r g y i n p u t p e r u n i t m a s s o f gas t r e a t e d , a r a t i o o f W/F, expressed a s watt-hours per pound. c is t h e ozone c o n c e n t r a t i o n expressed as w e i g h t f r a c t i o n . Β is t h e e n e r g y y i e l d of ozone g e n e r a t i o n expressed as p o u n d s of ozone p e r k i l o w a t t h o u r of p o w e r . T h e m e a s u r e of o z o n a t o r p e r f o r m a n c e selected w a s t h e e n e r g y y i e l d of ozone g e n e r a t i o n , B. I t is a p a r a m e t e r of t h e p r o d u c t . T h e e n e r g y i n p u t l e v e l of o z o n a t o r o p e r a t i o n , a, is also c o n s i d e r e d a m o s t i m p o r t a n t i n d e p e n d e n t v a r i a b l e . W i t h these t w o p o i n t s i n m i n d , i t is m o r e s i g n i f i c a n t t o p o i n t o u t t h e inconsistencies e n c o u n t e r e d i n t h e references of o t h e r i n v e s t i g a t o r s . T h e gas flow r a t e , F> i f m e a s u r e d , w a s n o t a l w a y s k e p t c o n s t a n t . T h e m e a s u r e m e n t of e l e c t r i c p o w e r , W, w a s o f t e n n e g l e c t e d . Obviously, the energy i n p u t , a, c a n be c a l c u l a t e d o n l y i n those cases i n w h i c h e l e c t r i c p o w e r w a s m e a s u r e d . N o t w i t h s t a n d i n g these o m i s s i o n s , t h e r a n g e of o p e r a t i n g c o n d i t i o n s w a s n o t a l w a y s c o m p a r a b l e t o present-day ozonators. C o m m e r c i a l o z o n a t o r s a r e o p e r a t e d i n t h e r a n g e of 50 t o 100 w a t t - h o u r s p e r p o u n d of gas t r e a t e d . H o w e v e r , i t w a s n o t u n c o m m o n t o find i n these previous investigations, ozonators operated between 300 a n d 400 watt-hours p e r p o u n d of gas. C o n c e n t r a t i o n , c, w a s t h e one p a r a m e t e r of o z o n a t o r p e r f o r m a n c e w h i c h s e r v e d as a c o m m o n d e n o m i n a t o r . F e w of t h e earliest e x p e r i m e n t e r s were c o n c e r n e d w i t h t h e o p e r a t i o n of o z o n a t o r s at o p t i m u m e n e r g y y i e l d s . T h i s c o u l d e x p l a i n t h e e x p e r i m e n t a l r e s u l t s o f t e n r e p o r t e d . T h e d e m a n d of i n d u s t r y f o r ozone a t a p r i c e w h i c h c o u l d b e c o m p e t i t i v e m a d e i t necessary t o r e s t u d y t h e effects of c e r t a i n gaseous c o n t a m i n a n t s i n o x y g e n w i t h respect t o t h e e n e r g y y i e l d of ozone g e n e r a t i o n . W i t h these t h i n g s i n m i n d , e x p e r i m e n t s w e r e p l a n n e d a n d c o n d u c t e d w i t h a f u l l scale u n i t o z o n a t o r designed a n d f u r n i s h e d b y T h e Welsbach Corp.

Equipment A s c h e m a t i c d i a g r a m of t h e o z o n a t o r a n d a s s o c i a t e d e q u i p m e n t i s s h o w n i n F i g u r e 1. A v i a t o r ' s b r e a t h i n g g r a d e o x y g e n , u s e d because of i t s l o w m o i s t u r e c o n t e n t , w a s d e l i v e r e d t o t h e o z o n a t o r t h r o u g h a p r e s s u r e r e g u l a t o r , a n i r o n case m e t e r , a n d a n orifice m a n o m e t e r . S u i t a b l e c o n n e c t i o n s were p r o v i d e d f o r m e a s u r i n g t h e f r o s t p o i n t , pressure, a n d temperature. I n a s i m i l a r m a n n e r t h e d i l u e n t gas w a s d e l i v e r e d t o a T - c o n n e c t i o n u p s t r e a m of the ozonator. T h e gas flow r a t e w a s m e a s u r e d b y a n orifice m a n o m e t e r , w i t h s u i t a b l e c o n n e c t i o n s f o r p r e s s u r e a n d t e m p e r a t u r e m e a s u r e m e n t . A l l flowmeters h a d b e e n previously calibrated according to accepted standard procedures. A s a m p l i n g p o i n t w a s p r o v i d e d f o r a n a l y s i s of t h e m i x e d gases. T h i s s e r v e d as a check o n t h e r a t i o of gases as d e t e r m i n e d b y t h e flow r a t e m e a s u r e m e n t s . T h e o z o n a t o r w a s c o n s t r u c t e d of stainless steel. T e m p e r e d glass w i n d o w s w e r e b o l t e d o n e a c h e n d of t h e a s s e m b l e d o z o n a t o r , u s i n g steel r i n g s . C o o l i n g w a t e r w a s s u p p l i e d a n d w i t h d r a w n a t c o n n e c t o r s l o c a t e d o n t o p of t h e o z o n a t o r s . T h e dimensions were : Jacket length Length of corona space Inside diameter S.S. tube Volume of ozonator and associated connections

42.75 inches 41.00 inches 3.122 inches 0.685 cu. ft.

A s t a n d a r d W e l s b a c h o z o n a t o r d i e l e c t r i c c o m p r i s i n g a 3 - i n c h b o r o s i l i c a t e glass t u b e w i t h a w r i n k l e d open e n d was used. A n i n t e r n a l conductive coating of metallic a l u m i n u m s e r v e d as a n i n n e r electrode. E l e c t r i c a l contact was established b v means


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of a n a l u m i n u m w i r e s p r i n g b e n t t o b e a r o n t h e i n s i d e of t h e t u b e a n d f a s t e n e d t o t h e high voltage connector. P r e s s u r e w a s c o n t r o l l e d b y t h e r e g u l a t o r , a n d t h e t o t a l t h r o u g h p u t o f gases w a s controlled b y a throttle valve at the outlet. A sample t r a p was provided for deter m i n a t i o n o f ozone c o n c e n t r a t i o n b y t h e n e u t r a l p o t a s s i u m i o d i d e m e t h o d . T h e electric power s u p p l y a n d metering system are shown schematically i n F i g u r e 2. P o w e r w a s s u p p l i e d t o t h e o z o n a t o r f r o m a h i g h v o l t a g e t r a n s f o r m e r w h i c h w a s supplied b y a Sola constant voltage transformer a n d a variable ratio transformer. A

Figure 1.

Schematic diagram of apparatus P. T. W. S. P.P.

Pressure Temperature Water Sample Frost point

v o l t m e t e r , a m m e t e r , a n d w a t t m e t e r w e r e c o n n e c t e d i n t h e p r i m a r y of t h e m a i n t r a n s former. A n electrostatic voltmeter was used to measure the secondary potential. I n a t y p i c a l experiment t h e ozonator was operated a t some energy i n p u t level w h i c h w o u l d be e x p e c t e d i n n o r m a l i n s t a l l a t i o n s . A t least 3 0 m i n u t e s w e r e a l l o w e d t o e s t a b l i s h s t e a d y - s t a t e c o n d i t i o n s . T h e r e a d i n g s of f l o w r a t e m e t e r s , a s s o c i a t e d p r e s sures, a n d t e m p e r a t u r e s as w e l l as e l e c t r i c a l m e t e r s w e r e r e c o r d e d . T h e s a m p l e s of t h e i n l e t o z o n a t o r gases were a n a l y z e d f o r c o m p o s i t i o n ; s a m p l e s of o z o n a t o r o u t p u t gases w e r e a n a l y z e d f o r ozone c o n c e n t r a t i o n . T h e r e s u l t s h a v e b e e n c a l c u l a t e d i n t e r m s of e n e r g y y i e l d of ozone g e n e r a t i o n e x p r e s s e d as p o u n d s of ozone p e r k i l o w a t t - h o u r of e l e c t r i c p o w e r , a n d p l o t t e d a g a i n s t t h e w e i g h t p e r c e n t of d i l u e n t gas i n t h e o x y g e n as s u p p l i e d t o t h e o z o n a t o r .


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OZONATOR-

115-VOLT 6 0 ^ j LINE


SOLA CONSTANT VOLTAGE TRANS.

Figure 2.

ELECTROSTATIC VOLTMETER-

Schematic diagram of electrical apparatus a n d meters /. Ammeter E. Voltmeter W. Wattmeter

Effect o f

Hydrogen

T h e r e s u l t s o f m i x i n g h y d r o g e n w i t h o x y g e n a r e s h o w n g r a p h i c a l l y i n F i g u r e 3. I t is a p p a r e n t t h a t e v e n a m o u n t s o f h y d r o g e n as l o w as a f e w h u n d r e d t h s o f 1 % w i l l a d v e r s e l y affect t h e e n e r g y y i e l d o f ozone g e n e r a t i o n . O n e e x p l a n a t i o n i s t h a t t h e h y d r o g e n r e a d i l y c o m b i n e s w i t h o x y g e n t o f o r m w a t e r . T h e presence o f w a t e r i n t h e oxygen could account for such a reduction i n energy yield. A n o t h e r explanation is t h a t t h e h y d r o g e n p e r se is r e s p o n s i b l e f o r t h e c h a n g e as r e p o r t e d . A n a t t e m p t w a s m a d e t o d i f f e r e n t i a t e b e t w e e n these t w o possible e x p l a n a t i o n s . I n this experiment, where hydrogen was admixed w i t h the oxygen, the a m o u n t of water produced i n the ozonator was determined b y the frost p o i n t m e t h o d . T h e difference b e t w e e n i n l e t a n d o u t l e t m o i s t u r e c o n t e n t w a s t a k e n as t h e a m o u n t p r o d u c e d b y t h e r e a c t i o n . O n l y a b o u t 4 % of t h e h y d r o g e n a d d e d w a s c o n v e r t e d t o w a t e r . T h e r e d u c t i o n i n e n e r g y y i e l d of ozone g e n e r a t i o n w a s g r e a t e r t h a n w o u l d b e p r o d u c e d b y t h i s a m o u n t o f w a t e r a d d e d as s u c h . I t is concluded t h a t h y d r o g e n itself is i n p a r t responsible f o r t h e r e d u c t i o n i n 0.30r

1

.

1

0.28

0.26 o.24i 0

$ : ι 0.04 0.08 PERCENT

Figure 3.

H

ι 0.12 2

Effect of hydrogen

F. 1.47 lb./hr. W. 99 watts σ. 68 watt-hr./lb.


308


e n e r g y y i e l d . S o m e of t h e h y d r o g e n — i n t h i s case at least 4 % — i s c o n v e r t e d t o w a t e r i n t h e presence of o x y g e n i n t h e d i s c h a r g e . T h e presence of t h i s w a t e r w i l l a d m i t t e d l y reduce t h e e n e r g y y i e l d , b u t f a i l s t o a c c o u n t f o r a l l of t h e loss as s h o w n . Effect of

Moisture

T h e r e s u l t s s h o w n i n F i g u r e 4 a r e t a k e n f r o m t h e w e i g h t e d a v e r a g e of s e v e r a l


0.30

FROST

I 0

1 100 WATER,

Figure 4.

POINT

°C.

1

1

200

300

P P M . BY

WEIGHT

1 400

Effect of moisture in oxygen F. 0.8 to 1.8 lb./hr. W. 105 to 109 watts a. 59 to 128 watt-hr./lb.

e x p e r i m e n t s . F o r t h i s r e a s o n , t h e e n e r g y i n p u t s a r e g i v e n as a r a n g e , i n s t e a d of specific v a l u e s . T h e s e r e s u l t s s h o w t h a t t h e presence of m o i s t u r e is t o be a v o i d e d , i f h i g h e n e r g y y i e l d s of ozone a r e d e s i r e d . F r o m s u c h a s t u d y as t h i s , i t was p o s s i b l e t o c a l c u l a t e t h e w a t e r p r o d u c e d i n t h e r e a c t i o n of h y d r o g e n a n d o x y g e n i n t h e d i s c h a r g e . T h e r e s u l t s here a r e p u r p o s e l y s h o w n i n t e r m s of t w o i n d e p e n d e n t v a r i a b l e s : f r o s t p o i n t , a n d w e i g h t of w a t e r i n o x y g e n . I t is t r u e t h a t —60° C . f r o s t p o i n t is n o t e q u a l t o 0 p . p . m . of w a t e r . H o w e v e r , t h e f r o s t p o i n t of t h e gas w a s t h e v a r i a b l e t h a t w a s m e a s u r e d e x p e r i m e n t a l l y . T h e w e i g h t of w a t e r , as s h o w n here, is a c a l c u l a t e d v a l u e , a n d is c o r r e c t e x c e p t f o r t h e range v e r y close t o 0 p . p . m . T h e m e a n s of p r e s e n t a t i o n i n F i g u r e 4 d o n o t a l l o w a m o r e a c c u r a t e c o m p a r i s o n of t h e t w o v a r i ables. I t is c o n c l u d e d t h a t f o r o p t i m u m o z o n a t o r o p e r a t i o n , t h e o x y g e n feed s h o u l d be d r i e d t o a f r o s t p o i n t of a t least —60° C , a n d t h a t i n t r o d u c t i o n of w a t e r t o t h e o x y g e n s h o u l d be a v o i d e d i n a l l cases. Effect of

Freon

I n F i g u r e 5 a r e s h o w n t h e r e s u l t s of a d d i n g F r e o n 12, d i c h l o r o d i f l u o r o m e t h a n e , t o oxygen. T h i s p a r t i c u l a r s t u d y w a s u n d e r t a k e n because i n s t a l l a t i o n of c o m m e r c i a l o z o n a t o r s , l e a k t e s t i n g of a l l j o i n t s , flanges, etc., a r e o f t e n p e r f o r m e d b y a d d i n g some F r e o n 12 t o t h e s y s t e m . T h e presence of t r a c e a m o u n t s of F r e o n i n a p r o p a n e flame r e n d e r s i t a v i v i d g r e e n . T h e q u e s t i o n w a s : H o w i m p o r t a n t is t h e c o m p l e t e r e m o v a l of F r e o n a f t e r a l e a k t e s t i n g o p e r a t i o n ? I t a p p e a r s t h a t as l i t t l e as t r a c e a m o u n t s w i l l cause serious r e d u c t i o n i n t h e e n e r g y y i e l d of a n o z o n a t o r . Effect o f

Argon

I n F i g u r e 6 a r e s h o w n t h e r e s u l t s of a d d i n g a r g o n t o o x y g e n . L i t t l e change is n o t e d i n t h e e n e r g y y i e l d f o r i n c r e m e n t s of a r g o n u p t o a b o u t 1 0 % . F o r l a r g e r


CROMWELL A N D MANLEY-EFFECT OF GASEOUS DILUENTS O N


0

0.4

02 PERCENT

Figure 5.

ENERGY

309

0.6

CCI F 2

2

Effect of Freon 12

F. 1.14 lb./hr. W. 98 watts a. 86 watt-hr./lb.

a m o u n t s , a g r a d u a l r e d u c t i o n i n t h e e n e r g y y i e l d is n o t e d . A t 5 0 % a r g o n , t h e o b s e r v e d y i e l d is 8 8 % of t h a t o b t a i n e d w i t h p u r e o x y g e n . O n e p u r p o s e i n t h e s t u d y of a r g o n w a s t o use i t as a n i n e r t d i l u e n t t o r e d u c e t h e p o s s i b i l i t y of flame a n d e x p l o s i o n i n o z o n i z a t i o n r e a c t i o n s . F r o m t h i s s t u d y i t is possible t o p r e d i c t t h e e x p e c t e d loss i n ozone p r o d u c t i o n as a r e s u l t of t h e use of a r g o n i n s u c h a n a p p l i c a t i o n . A n o t h e r p u r pose of t h i s s t u d y w a s t o find t h e effect of a m o u n t s of a r g o n t h a t w o u l d be e x p e c t e d n o r m a l l y i n c o m m e r c i a l o x y g e n . A s t h i s a m o u n t is less t h a n 1 % , i t is c o n c l u d e d t h a t n o a d v e r s e effect s h o u l d be e x p e c t e d . Effect of

Carbon

Dioxide

I n F i g u r e 7 a r e s h o w n t h e r e s u l t s of a d d i n g c a r b o n d i o x i d e t o o x y g e n before o z o n i z i n g . H e r e a g a i n , as i n t h e case of a r g o n , i t is possible t o r e d u c e t h e h a z a r d of flame a n d e x p l o s i o n i n o z o n i z a t i o n r e a c t i o n s b y u s i n g c a r b o n d i o x i d e as a n i n e r t d i l u e n t . I n t h e p r i m a r y p u r p o s e of t h i s i n v e s t i g a t i o n , h o w e v e r , t h e a m o u n t s of c a r b o n d i o x i d e e x p e c t e d w e r e t h e r e s u l t of o x i d a t i o n of o r g a n i c c o n s t i t u e n t s i n t h e o x y g e n — n o m o r e t h a n s e v e r a l h u n d r e d p a r t s p e r m i l l i o n . I t is a p p a r e n t t h a t l i t t l e loss i n e n e r g y y i e l d is expected for carbon dioxide u p to 1 0 % . U s i n g 5 0 % carbon dioxide w i l l reduce t h e e n e r g y y i e l d t o a b o u t 8 5 % of t h a t e x p e c t e d w i t h p u r e o x y g e n . I n t h e p r e v i o u s

0.201 0

I

I

I

25

50

75

PER

Figure 6.

CENT

A

Effect of argon




310

e x a m p l e i t w a s s h o w n t h a t 5 0 % a r g o n w o u l d g i v e a n e n e r g y y i e l d of 8 8 % of t h a t e x p e c t e d w i t h p u r e o x y g e n . T h e p o s s i b i l i t y of r e a c t i o n s w i t h i n t h e d i s c h a r g e a r e u n d e r s t a n d a b l e w i t h c a r b o n d i o x i d e , b u t n o t w i t h a r g o n . J u s t w h a t i t is t h a t p r o d u c e s t h e same decrease i n e n e r g y w i t h t w o d i f f e r e n t d i l u e n t s is n o t e x p l a i n e d b y these results. F u t u r e e x p e r i m e n t s w i l l b e n e c e s s a r y t o a n s w e r these q u e s t i o n s .


0.30,

,

.

_ 20

40

,

0.26

0.24

PER CENT C 0 Figure 7.

2

Effect of carbon dioxide F. 1.52 lb./hr. W. 100 watts a. 66 watt-hr./lb.

Effect o f

Nitrogen

I n F i g u r e 8 a r e s h o w n t h e r e s u l t s of m i x i n g n i t r o g e n w i t h o x y g e n . T h e m o s t s u r p r i s i n g t h i n g is t h a t e n e r g y y i e l d is i n c r e a s e d w h e n n i t r o g e n is e m p l o y e d i n t h e r a n g e f r o m 1 u p t o a b o u t 1 0 % . W h e n a b o v e 1 0 % n i t r o g e n is p r e s e n t i n o x y g e n , t h e e n e r g y y i e l d shows a g r a d u a l b u t s t e a d y decrease. O n e i m p o r t a n t c o n c l u s i o n is t h a t c o m m e r cial oxygen for ozonators need n o t be 9 9 . 5 % p u r e . T h e 96 to 9 7 % p u r i t y w o u l d n o t o n l y g i v e a h i g h e r e n e r g y y i e l d of ozone b u t also b e m o r e e c o n o m i c a l t o p r o d u c e . T h e s h a p e of t h e c u r v e as d r a w n m i g h t l e a v e r e a s o n a b l e d o u b t as t o t h e e x p e c t e d m a x i m u m . O t h e r e x p e r i m e n t s w e r e c o n d u c t e d f o r i n c r e m e n t s of n i t r o g e n less t h a n 6 % a n d t h e r e s u l t s a r e s h o w n i n F i g u r e 9. I t is c o n c l u d e d t h a t t h e a d d i t i o n of e v e n s m a l l

0.30

0.28

0. 26

0.24 10 PER CENT Figure 8.

30

20 N

2

Effect of nitrogen



CROMWELL A N D MANLEY-EFFECT OF GASEOUS DILUENTS O N

ENERGY

311

0.24

0.22

0.20


0.18

2

4

PER CENT Figure 9.

No

Effect of nitrogen

F. 0.7 to 1.2 lb./hr. W. 85 to 105 watts a. 87 to 93 watt-hr./lb.

a m o u n t s of n i t r o g e n , of t h e o r d e r of 1 t o 2 % , is sufficient t o p r o d u c e these u n e x p e c t e d r e s u l t s . T h e c o n t r o l of n i t r o g e n t o w i t h i n o p t i m u m v a l u e s is i m p o r t a n t i n c o m m e r c i a l ozonator operation. Effect o f C a r b o n

Monoxide

I n F i g u r e 10 a r e s h o w n t h e r e s u l t s of m i x i n g c a r b o n m o n o x i d e w i t h o x y g e n . T h i s is a n o t h e r d i l u e n t w h i c h gives a s u r p r i s i n g a n d u n e x p e c t e d increase i n t h e e n e r g y y i e l d . S o m e w h a t less c a r b o n m o n o x i d e t h a n n i t r o g e n is necessary t o p r o d u c e t h i s i n crease. T h e presence of c a r b o n m o n o x i d e c a n be e x p e c t e d i n t h e p r o d u c t s of t h e recycled oxygen system. I f the organic contaminants are burned, carbon dioxide a n d w a t e r a r e e x p e c t e d ; b u t i t is n o t u n r e a s o n a b l e t o e x p e c t s o m e i n c o m p l e t e o x i d a t i o n products, including carbon monoxide. I t is c o n c e i v a b l e t h a t t h e c o n t r o l of a n o p t i m u m c a r b o n m o n o x i d e c o n t e n t w i l l be a f a c t o r t h a t s o m e ozone p l a n t s c a n n o t a f f o r d t o ignore.

0.34i

0.281 0

I 2

I 4

I 6

PER CENT CO Figure 10.

Effect of carbon monoxide F. 1.52 lb./hr. W. 90 watts a. 59 watt-hr./lb.


312

A D V A N C E S IN

CHEMISTRY SERIES

Conclusions O f t h e seven d i l u e n t s s t u d i e d , t h e greatest loss i n e n e r g y y i e l d r e s u l t e d f r o m t h e presence of less t h a n 1 % of h y d r o g e n , w a t e r , o r F r e o n 12. A g r a d u a l decrease i n e n e r g y y i e l d r e s u l t e d f r o m a d d i t i o n of e i t h e r c a r b o n d i o x i d e o r a r g o n t o o x y g e n ; a m o u n t s u p t o 5 0 % r e d u c e d t h e e n e r g y y i e l d to o n l y 8 5 % of that expected w i t h pure oxygen.


F i n a l l y , t h e presence of e i t h e r c a r b o n m o n o x i d e or n i t r o g e n i n a m o u n t s u p t o 1 0 % a p p a r e n t l y i n c r e a s e d t h e e n e r g y y i e l d of ozone g e n e r a t i o n i n o x y g e n . I n a m o u n t s g r e a t e r t h a n 1 0 % , a g r a d u a l decrease i n e n e r g y y i e l d r e s u l t e d . Literature

Cited

(1) B r i n e r , E., B e v e r , B., Helv. Chim. Acta 25, 900-6 (1942). Influence of d i l u t i n g gas i n p r o d u c t i o n of ozone f r o m oxygen b y electric discharge. (2) B r i n e r , E., M o n n i e r , D., Ibid., 25, 844-51 (1951). D i s t r i b u t i o n of electric energy i n p r o d u c t i o n of ozone a n d o x i d a t i o n of n i t r o g e n in oxygen-nitrogen mixtures i n a n elec tric discharge. (3) G l o c k l e r , G., Lind, S. C . , " E l e c t r o c h e m i s t r y of Gases a n d O t h e r D i e l e c t r i c s , " W i l e y , N e w Y o r k , 1939. (4) J u l i a r d , Μ . Α., Bull. acad. roy. Belg. 12, 914-20 (1926). P r o d u c t i o n of ozone b y electric discharge i n presence of foreign gases. (5) P i n k u s , Α., J u l i a r d , Μ. Α., J. chim. phys. 24, 370-90 (1927). P r o d u c t i o n of ozone b y electric discharge in presence of foreign gases. (6) R i d e a l , Ε. K., " O z o n e , " C o n s t a b l e , L o n d o n , 1920. (7) V o s m a e r , Α., " O z o n e , Its M a n u f a c t u r e , P r o p e r t i e s , a n d U s e s , " V a n N o s t r a n d , N e w Y o r k , 1916. RECEIVED

for review May 17, 1957.

A c c e p t e d J u n e 19, 1957.


Effect of Gaseous Diluents on Energy Yield of Ozone Generation

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