Removal of Trace Contaminants from the Air - ACS Publications

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Removal of Contaminants from Submarine Atmospheres

Downloaded by 80.82.77.83 on January 16, 2018 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0017.ch001

HOMER W. CARHART and JOSEPH K. THOMPSON U.S. Naval Research Laboratory, Washington, D. C. 20375

A submarine can be described very simply as a large bubble of air, encased in steel, and f i l l e d with machinery and men. This vessel is expected to go to sea and cruise under water for many weeks without access to surface air. The purpose of this paper is to describe some of the constituents of this large air bubble and then tell some of what is being done to maintain a livable atmosphere therein. A few problems that have arisen w i l l be specifically mentioned. The Chemistry Division of the Naval Research Laboratory has been engaged in submarine atmosphere research since 1929. With the advent of the nuclear submarine and its prolonged submergence capability about 1955, research on closed atmospheres has become an important field of study in the Navy (1, 2, 3, 4, 5, 6). Techniques developed in connection with nuclear submarine atmosphere research have also been extended and applied to atmosphere research for the Navy's SeaLab experiments. In the SeaLab experiments, men lived and worked for extended periods in and around a stationary underwater habitat at pressures determined by the depth of the water (7, 8). However, the work discussed here deals primarily with the nearly constant-pressure atmosphere of nuclear submarines. The progress that has been made results from the contributions of many people operating in a variety of scientific disciplines. Composition of the Atmosphere in Underwater Craft Table I, Column 1, shows the approximate composition of a typical nuclear submarine atmosphere. It is to be noted that, in addition to the normal constituents of air—nitrogen, oxygen, and a trace of argon, there are relatively small amounts of carbon dioxide, carbon monoxide, methane, hydrogen, and traces of a great variety of other compounds. These minor components cause most of the problems in maintaining air quality. Many of the 1 Deitz; Removal of Trace Contaminants from the Air ACS Symposium Series; American Chemical Society: Washington, DC, 1975.


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components a r e p r e s e n t i n c o n c e n t r a t i o n s o f a few p a r t s p e r m i l l i o n or l e s s . F o r c o m p a r i s o n , T a b l e I , Column 2, shows t h e a p p r o x i m a t e c o m p o s i t i o n o f t h e a t m o s p h e r e i n SeaLab I I , i n w h i c h t h e t o t a l p r e s s u r e was t y p i c a l l y 7 a t m o s p h e r e s . Man r e q u i r e s an o x y g e n p a r t i a l p r e s s u r e o f a p p r o x i m a t e l y 152 t o r r t o s u s t a i n l i f e , and he c a n t o l e r a t e o n l y c e r t a i n l i m i t e d p a r t i a l p r e s s u r e s of t h e v a r i o u s c o n t a m i n a n t s . I n SeaLab I I t h e s e p a r t i a l p r e s s u r e l i m i t s a r e much l o w e r p e r c e n t a g e s o f t h e t o t a l p r e s s u r e t h a n t h e y a r e f o r t h e one a t m o s p h e r e p r e s s u r e o f t h e n u c l e a r s u b m a r i n e . The t e c h n i q u e s o f gas and l i q u i d c h r o m a t o g r a p h y and o f mass s p e c t r o s c o p y h a v e b e e n u s e d i n a c o n t i n u i n g p r o g r a m o f i d e n t i f i c a t i o n and a n a l y s i s o f t h e s e t r a c e c o n t a m i n a n t s i n t h e submarine atmosphere. Many o f t h e c o n t a m i n a n t s , p a r t i c u l a r l y o r g a n i c compounds o f l e s s t h a n 10 c a r b o n a t o m s , h a v e b e e n q u a n t i t a t i v e l y measured. Others have been q u a l i t a t i v e l y i d e n t i fied. Many more d i s c r e t e components h a v e b e e n o b s e r v e d b u t n o t identified. Over 400 d i s c r e t e p e a k s w e r e r e c o r d e d i n one gas c h r o m a t o g r a m o f a t m o s p h e r i c c o n t a m i n a n t s c o l l e c t e d on c h a r c o a l and l a t e r e x t r a c t e d f o r a n a l y s i s . The n e x t s e v e r a l t a b l e s l i s t some o f t h e compounds t h a t h a v e b e e n f o u n d i n n u c l e a r s u b m a r i n e atmospheres. T h e s e a r e g r o u p e d by c h e m i c a l t y p e f o r c o n v e n i e n c e i n l i s t i n g and d i s c u s s i o n . Among t h e h y d r o c a r b o n s , a r o m a t i c s and t h e i r d e r i v a t i v e s p r e s e n t t h e g r e a t e s t p r o b l e m f r o m a t o x i c o l o g i c a l s t a n d p o i n t ; h e n c e , t h e y h a v e b e e n s t u d i e d more t h o r o u g h l y t h a n some o f t h e o t h e r s ( 9 , 1 0 ) . T a b l e I I shows a l i s t o f i n o r g a n i c compounds t h a t h a v e b e e n i d e n t i f i e d i n n u c l e a r s u b m a r i n e a t m o s p h e r e s ( 9 ) . Oxygen f o r a t m o s p h e r e r e p l e n i s h m e n t i s g e n e r a t e d c o n t i n u o u s l y a t 3000 pounds p e r s q u a r e i n c h by t h e e l e c t r o l y s i s o f w a t e r , t h a n k s t o t h e ample s u p p l y o f power a v a i l a b l e f r o m t h e n u c l e a r r e a c t o r . F o r e v e r y m o l e o f o x y g e n f o r m e d , two m o l e s o f h y d r o g e n a r e produced. T h i s h y d r o g e n must be pumped o v e r b o a r d . Any l e a k a g e , of c o u r s e , goes i n t o t h e s h i p ' s a t m o s p h e r e . Another source of h y d r o g e n , and a l s o o f a r s i n e and s t i b i n e , i s t h e bank o f l e a d a c i d s t o r a g e b a t t e r i e s w h i c h t h e s h i p c a r r i e s as a n emergency power s o u r c e . Carbon d i o x i d e i s a product of r e s p i r a t i o n . Most of t h i s i s a b s o r b e d f r o m t h e a i r by a m o n o e t h a n o l a m i n e (MEA) s c r u b b e r . Spent amine i s s u b s e q u e n t l y h e a t e d t o r e l e a s e t h e CO 2» w h i c h i s pumped overboard. The r e g e n e r a t e d amine i s t h e n c o o l e d and r e c y c l e d t h r o u g h t h e s c r u b b e r . I n t i m e , t h i s MEA p a r t i a l l y b r e a k s down to f o r m ammonia. B o t h ammonia and MEA v a p o r i n t h e a i r a r e o x i d i z e d i n the c a t a l y t i c burner (see below) t o form o x i d e s of n i t r o g e n . Hydrogen f l u o r i d e i s a product of d e c o m p o s i t i o n of c e r t a i n r e f r i g e r a n t g a s e s i n t h e c a t a l y t i c b u r n e r . Ozone and n i t r o g e n d i o x i d e a r e p r o d u c e d by i m p r o p e r l y f u n c t i o n i n g e l e c t r o s t a t i c p r e c i p i t a t o r s , p r e s e n t t o remove a e r o s o l s f r o m the a i r . C a r b o n m o n o x i d e i s a m a j o r p r o d u c t o f s m o k i n g , as a r e a e r o s o l s and a v a r i e t y o f o t h e r p y r o l y s i s p r o d u c t s f r o m t o b a c c o .

Deitz; Removal of Trace Contaminants from the Air ACS Symposium Series; American Chemical Society: Washington, DC, 1975.


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AND THOMPSON

Submarine

Atmospheres

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The c a t a l y t i c b u r n e r i s a f l o w - t h r o u g h r e a c t o r whose b e d i s packed w i t h H o p c a l i t e , a c a t a l y s t c o n s i s t i n g o f c o p r e c i p i t a t e d o x i d e s o f c o p p e r a n d manganese. T h i s c a t a l y s t , when h e a t e d t o 315°C, q u a n t i t a t i v e l y o x i d i z e s H^, CO, a n d many o r g a n i c compounds t o CO^ a n d H^O. Methane i s a n e x c e p t i o n ; i t i s n o t o x i d i z e d a p p r e c i a b l y a t o r d i n a r y o p e r a t i n g t e m p e r a t u r e s . The c a t a l y t i c b u r n e r ' s e f f e c t o n c e r t a i n o t h e r compounds w i l l b e d i s c u s s e d l a t e r i n t h i s paper. T a b l e I I I l i s t s a l i p h a t i c hydrocarbons t h a t have been i d e n t i f i e d i n n u c l e a r submarine atmospheres ( 9 ) . Except f o r methane, t h e s e come l a r g e l y f r o m p a i n t s , s e a l e r s , a n d cements t h a t c o n t i n u e t o exude v a p o r s l o n g a f t e r a p p l i c a t i o n a n d f r o m s o l v e n t s , o i l s , a n d f u e l s . Methane i s a m a j o r c o n t a m i n a n t i n t h e s u b m a r i n e a t m o s p h e r e . The p r i n c i p a l s o u r c e s o f methane are f l a t u s and the d e c o m p o s i t i o n o f wastes i n the s h i p ' s s e p t i c t a n k . Methane i s n o t a p p r e c i a b l y o x i d i z e d i n the c a t a l y t i c burner; hence, i t s c o n c e n t r a t i o n continues t o i n c r e a s e as l o n g a s t h e s h i p i s c l o s e d . I n a prolonged closed period t h e methane c o n c e n t r a t i o n may r e a c h 500 p a r t s p e r m i l l i o n o r more. F o r t u n a t e l y , t h i s c o n c e n t r a t i o n i s w e l l b e l o w t h e 5.3% minimum c o n c e n t r a t i o n r e q u i r e d f o r f l a m m a b i l i t y i n a i r . A l s o , methane i s r e l a t i v e l y n o n - t o x i c ; s o i t s p r e s e n c e i s o f no g r e a t concern. T a b l e I V shows a l i s t o f a r o m a t i c h y d r o c a r b o n s t h a t h a v e been q u a n t i t a t i v e l y measured i n n u c l e a r submarine atmospheres (9, 10). T h e s e a l s o can b e t r a c e d t o s o l v e n t s , o i l s , c e m e n t s , and s e a l e r s , a s w e l l a s t o b y - p r o d u c t s o f s m o k i n g , c o o k i n g , and d e c o m p o s i t i o n o f h o t o i l s i n s h i p ' s m a c h i n e r y . A r o m a t i c s make up a b o u t 2 5 % o f t h e t o t a l h y d r o c a r b o n c o n t e n t o f t h e s u b m a r i n e atmosphere. T a b l e V l i s t s some o f t h e u n s a t u r a t e d a n d a l i c y c l i c compounds t h a t have been i d e n t i f i e d i n submarine atmospheres ( 9 ) . T a b l e V I shows o t h e r m i s c e l l a n e o u s compounds t h a t h a v e b e e n found i n submarine atmospheres ( 9 ) . Monoethanolamine, o f c o u r s e , comes f r o m t h e C0~ s c r u b b e r . E t h y l a l c o h o l comes l a r g e l y f r o m t h e m e d i c a l d e p a r t m e n t . C e r t a i n o t h e r s c a n be t r a c e d t o p a i n t and cement s o l v e n t s . T a b l e V I I shows some o f t h e c h l o r i n a t e d compounds t h a t h a v e been i d e n t i f i e d ( 9 ) . These have been p a r t i c u l a r l y t r o u b l e s o m e — n o t o n l y b e c a u s e o f t h e i r own t o x i c i t y , b u t a l s o b e c a u s e some a r e decomposed o r c o n v e r t e d i n t h e c a t a l y t i c b u r n e r t o f o r m o t h e r h a r m f u l m a t e r i a l s . A p a r t i c u l a r example, m e t h y l c h l o r o f o r m , w i l l be d i s c u s s e d l a t e r i n t h i s p a p e r . T a b l e V I I I l i s t s r e f r i g e r a n t and p r o p e l l a n t gases t h a t have b e e n f o u n d on b o a r d s u b m a r i n e s . These g a s e s come f r o m l e a k s i n the r e f r i g e r a t i o n systems and from p r e s s u r i z e d a e r o s o l c o n t a i n e r s t h a t h a v e b e e n b r o u g h t on b o a r d ( 9 ) . The f o r e g o i n g t a b l e s show a l a r g e number o f compounds t h a t have b e e n i d e n t i f i e d i n s u b m a r i n e a t m o s p h e r e s . T h e s e a r e n o t i s o l a t e d cases. F i g u r e 1 shows a c o m p a r i s o n o f t h e c o n c e n t r a t i o n s


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Table I . Atmospheres i n undersea c r a f t ; approximate v a l u e s , d r y b a s i s Nuclear Submarines

Gas

Ar He CO


C H

4 Higher organics H„

Table I I .

78% 19-21% 0.8-1.3% 0.9% 0 TOTAL HYDROCARBON 34 m g / M 3

SAMPLE r INJECTION

I-


IlI

10

Figure 4. submarine

6 4 2 T I M E (MINUTES)

0

Chromât ο gram of organic vapor content in atmosphere as determined by NRL Total Hydrocarbon Analyzer

Figure 5. Effluent n-hexane concentra tion as a function of total hydrocarbon adsorbed. •—weighted values for ndecane and n-hexane. O-weighted value for n-decane; value for n-hexane calcu lated from concentration-time product. M, ·—values for carbon bed with built-in leak.

10 TOTAL

15

HYDROCARBON

20

25

ADSORBED


30 (wt. percent)


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but also most known fire fighting agents can be hazardous in a closed environment. The relationship between oxygen partial pressure and percentage composition of the atmosphere has suggested a possible way to combat submarine fires." Man requires an oxygen partial pressure of about 152 torr. In our normal atmosphere, this is about 20% of the total pressure. At a total pressure of 1.5 atmospheres, 152 torr is only 14% of the total, but i t is sufficient for man's needs. However, many open flame fires which w i l l continue to burn in 20% oxygen w i l l be extinguished at 12-14%. Thus, i f one can increase the total pressure in a closed environment by adding nitrogen, the oxygen partial pressure w i l l s t i l l remain at 152 torr, and man can s t i l l survive. However, the percent of oxygen would be lowered to values low enough so that combustibles would not burn. This concept of pressurization with nitrogen to snuff out fires in submarines is now being studied extensively in the laboratory and is showing a high degree of promise (21, 22, 23). Literature Cited 1.

Miller, R. R., and Piatt, V. R., Eds., "The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 5465, Washington, D. C., April 1960. 2. Piatt, V. R., and Ramskill, Ε. Α., Eds., "Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 5630, Washington, D. C., July, 1961. 3. Piatt, V. R., and White, J . C., Eds., "Second Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 5814, Washington, D. C., August, 1962. 4. Carhart, H. W., and Piatt, V. R., Eds., "Third Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 6053, Washington, D. C., December, 1963. 5. Lockhart, L. Β., and Piatt, V. R., Eds., "Fourth Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 6251, Washington, D. C., March, 1965. 6. Alexander, A. L., and Piatt, V. R., Eds., "Fifth Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 6491, Washington, D. C., January, 1967.


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Submarine Atmospheres

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7. Umstead, M. E., and Smith, W. D., "Trace organic contaminants in the atmosphere of SEALAB II; preliminary report on," Naval Research Laboratory letter report 6180-89:MEU:WDS:ec, 26 May 1966. 8. Umstead, M. E . , "Carbon monoxide in the atmosphere of SEALAB II; information on," Naval Research Laboratory letter report 6180-55A:MEU:ec, 31 March 1966. 9. Carhart, H. W., and Piatt, V. R., Eds., "Third Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 6053, Chapter 8, Washington, D. C., December, 1963. 10. Johnson, J . E . , Chiantella, A. J., Smith, W. D., and Umstead, M. E . , "Nuclear Submarine Atmospheres: Part 3 Aromatic Hydrocarbon Content," Naval Research Laboratory Report 6131, August, 1964. 11. Piatt, V. R., and Ramskill, Ε. Α., Eds., "Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory Report 5630, Chapter 18, Washington, D. C., July, 1961. 12. Bitner, J . L., Naval Research Laboratory, Washington, D. C., Personal communication. 13. Carhart, H. W., and Piatt, V. R., Eds., "Third Annual Progress Report: The Present Status of Chemical Research in Atmosphere Purification and Control on Nuclear-Powered Submarines," Naval Research Laboratory report 6053, Chapter 9, Washington, D. C., December, 1963. 14. Christian, J . G., and Johnson, J . E . , "Catalytic Combustion of Nuclear Submarine Atmospheric Contaaminants," Naval Research Laboratory Report 6040, Washington, D. C., March 1964. 15. Musick, J . K . , and Williams, F. W., Ind. Eng. Chem., Prod. Res. Develop., (1974), 13, 175-179. 16. Musick, J . Κ., and Williams, F. W., "Catalytic Decomposition of Halogenated Hydrocarbons with Hopcalite Catalyst," American Society of Mechanical Engineers Publication 75-ENAs-17, New York, Ν. Y . , 1975. Presented at Intersociety Conference on Environemntal Systems, San Francisco, California, July 21-24, 1975. 17. Johnson, J . E . , "Nuclear Submarine Atmospheres: Analysis and Removal of Organic Contaminants," Naval Research Laboratory Report 5800, Washington, D. C., September 1962. 18. Eaton, H. G., Umstead, M. E., and Smith, W. D., J . Chromatographic S c i . , (1973), 11, 275-278. 19. Umstead, M. E . , Smith, W. D., and Johnson, J . E . , "Submarine Atmosphere Studies Aboard USS Sculpin," Naval Research Laboratory Report 6074, Washington, D. C., February, 1964. 20. Eaton, H. G., Thompson, J . K., and Carhart, H. W., "Feasibility of the Total Hydrocarbon Analyzer for Evaluating


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the Life of Charcoal Beds," Naval Research Laboratory Report 7712, Washington, D. C., April, 1974. 21. Carhart, H. W., and Gann, R. G., "Fire Suppression in Submarines," Report of NRL Progress, May, 1974. 22. Tatem, P. Α., Gann, R. G., and Carhart, H. W., Combustion Sci. and Technol., (1973), 7, 213. 23. Tatem, P. Α., Gann, R. G., and Carhart, H. W., Combustion Sci. and Technol., in press.


Removal of Trace Contaminants from the Air - ACS Publications

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