Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested

Kanda, S.

Kondo, S.

Matsumura, H.

Otsubo, K.

Otsuji, K.

Satoh, S.

Sawada, T.

English

NASA Technical Reports Server

- 
N88-12261 
PRELIMINARY EXPERIMENTAL RESULTS OF GAS RECYCLING SUBSYSTEMS 
EXCEPT CARBON DIOXIDE CONCENTRATION 
K. Otsu j i *,T. Sawada*, S. Sa toh**, S .  Kanda***, H.Ma tsumura** *, S. Kondo+,and K.Otsubo+' 
*Mitsubishi Heavy Industries, Ltd. 10, Oye-clio, Minato-ku, Nagoya, 
455, Japan. **Mitsubishi Heavy Industries, Ltd. 2-1-1, Shinhama, 
Arai-cho, Takasago, 676,  Japan. ***Kawasaki Heavy Industries. Ltd. 
3-1-1, Higashikawasaki-cho. Chuo-ku, Kohe, 650-91, Japan. +Kawaju 
Marine Enq. Co, Ltd. 3-1-1, Higashikawasaki-cho, Chuo-ku, Kobe, 
650-91, Japan. ++National Aerospace Laboratory, 1880, shindaiji-cho, 
Chofu, Tokyo, 182, Japan. 
ABSTRACT 
Oxygen concentration and separation is an essential factor for air recycling in a CELSS. 
Furthermore, if the value o€ the plant assimilatory quotient is not coincident with that 
o €  the animal respiratory quotient, the recovery of O2 from the concentrated C02 
through chemical methods will become necessary to balance the gas contents in a CELSS. 
Therefore, oxygen concentration and separation equipment using Salcomine and 02 recovery 
equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested. 
1. BASIC CONSIDERATION ON GAS RECYCLING 
Fundamental €unctions of gas recycling in CELSS, as shown in Fig. 1. 1, are to separate 
each component, such as 02, Cog, and N2 gases, and to concentrate and store each gas 
in order to supply appropriate gas concentration for human beings, plants and algae. 
2. OXYGEN RECOVERY FROM CONCENTRATED CARBON DIOXIDE 
Many research and development ef€orts have been conducted for the recovery of  oxygen from 
concentrated C02 by the catalytic hydrogenization process. The Bosch reaction utilizes 
an iron catalyst and produces carbon (C) and water (H20) with CO as an intermediate 
product /l/. Product water is further electrolyzed to recover 0 2  for animal respiration 
and H2 for subsequent hydrogenization. The Sabatier reaction utilizes a ruthenium (Ru) 
catalyst and produces methane and water /2/. An additional CH4 cracking process 
providing C and H2 is necessary to make the Sabatier reaction comparable to the Bosch 
reaction /3/. 
Mitsubishi Heavy Industries, Ltd. (MHI) has 
been involved in CELSS research €or several 
years /4/ under the direction oE the National 
Aerospace Laboratory and conducted the 
experimental program to evaluate the basic 
characteristics and performance of the two 
oxygen recovery processes. 
2.1 Once Throuph Tests 
In order to determine the basic characteristics 
of each reaction, once through tests of C02 
reaction with H2 on the catalyst are 
performed. Fig. 2.1 shows the schematic of the 
test set up. 
Bosch Reaction Fig. 2.2 shows the reaction 
rate of C02 v s .  reaction temperature in the 
first Bosch reaction, as well as the reaction 
rate of CO vs. temperature in the second Bosch 
reaction. The different nature of the two 
reaction rate curves suggests a phased process 
concept using two reactors operating at 
different temperature ranges to obtain higher 
pcrtormance in the Bosch C02 cracking process. 
Fig. 1.1 Fundamental function of 
Gas Recycling Sys tein 
HI A i  TliE 
D X l - -  I,J 
Fig. 2.1 Bosch/Sahatier 
Once Through Test Setup 
PRWm€NG PAGE BLANK NOT 
67 
https://ntrs.nasa.gov/search.jsp?R=19880002879 2020-03-20T08:39:42+00:00Z
I I I 0 
4 1 ~ )  v x i  I,IXI a n i  Hini S U H I  
Fig. 2.2 Reaction Efficiency vs Temperature 
of Bosch Reaction 
I<RJ) I . *  , 1 * 1 1 <  ( 1 I 
Sabatier Reaction Fig. 2.3 shows the reaction rate 
of C02 vs mole ratio of H2/C02 in the feed gas 
mixture of the first Sabatier reaction. Reaction 
rate of more than 9 9  % is achieved with a little bit 
higher ratio (4.5) than the stoichiometric value. 
As for the second Sabatier reaction, reaction rate 
of CH4 vs. time after start of the reaction is 
presented in Fig. 2.4. Very rapid degradation is 
observed for the catalytic reactions using Pt or Ni, 
while a steady and much higher conversion efficiency 
is observed in pyrolytic reaction on silica wool 
filler. 
2.2 Recycle Test 
A Recycle Test Apparatus was prepared based on the 
once through test results as shown in Fig. 2.5. 
c 
= -  c 
Fig. 2.3 
11- IO 
5 ,,,,,I ,,,, nI.,r,c \ I l l l C  L ' . l I k I ,  l l l ~ ~ ~ ~ ~ ~ ~  
C 0 2  Reaction Eeficiency vS 
H2/C02 Mole Ratio 
for Sabatier First Reaction 
Fig. 2.4 CH4 Creacking Efficiency vs 
Time for Sabatier Second Reaction 
The supply rate of mixture gas is shown in Fig. 2.6. 
The amounts of processed C02 are 0.15 kg/day 'and 
0.42 kg/day for Bosch and Sabatier, respectively. 
Energy required for the above processes were 
estimated and the Sabatier process showed several 
times less energy use than Bosch process. The 
character of deposit carbon in the Bosch process was 
a loose powder form, while a hard solid block was 
obtained from the Sabatier reactor. This fact has an 
important meaning for maintainance operations to 
periodically extract carbon on orbit. 
Thus, the O2 recovery system with Sabatier methane 
cracking shows a good possibility for application in 
CELSS and Space Station. 
68  
TI* 1,- (I.,, <I1 HI ,,,, ,>,, I h , l  
Fig. 2 . 6  Feed gas Supply Rate in 
Bosch/Sabatier Recycle Process 
ORIGINAL PAGE 13 
OB POOR QUALITY 
3 .  OXYGEN SLI'AIL\'I'ION SYSTEM USING SAI.COFIINE 
3.1 
Kawasaki lleavy I n d u s t r i e s  Ltd. (KIII) has  
been involved  i n  CELSS research  under 
c o n t r a c t  w i t h  t h e  Nat iona l  Aerospace 
Laboratory (NAL) /5/. 
Fig .  3 .1  shows t h e  func t ion  of O2 sepa- 
r a t i o n  arid concen t r a t ion  system, con- 
cern ing  t h e  COz and N 2  s epa ra t ion  and 
concen t r a t ion .  In t h e  F ig .  3.1, t h e  i n -  
l e t  gas  i s  mixture  o f  0 2 ,  COz and N z .  A t  
t h e  COz c o n c e n t r a t e r ,  COZ is sepa ra t ed  
and concen t r a t ed ,  and s t o r e d  i n  t h e  
COz gas  b o t t l e .  A t  t h e  OZ c o n c e n t r a t e r ,  F ig .  3 .1  Function of Oxygen Sepa ra t ion  
0 2  i s  sepa ra t ed  antl conccn t r a t cd ,  and and Concent ra t ion  System 
s to rcd  i n  t h e  Oz gas b o t t l e .  The r e s i d u a l  
i s  N2 gas  and t h i s  i s  s t o r e d  i n  
t h r e e  (3) components, CO,, O,, and N, having h igh  p u r i t i e s .  
There a r e  many methods f o r  Cot s e p a r a t i o n  and concen t r a t ion .  ;'he s t u d i e s  repor ted  h e r e  
a r e  focused cn t h e  Oz sepa ra t ion  antl concen t r a t ion  system us ing  Salcomine. 
Salcomine absorbs  t h e  0 2  under normal tempera ture  (lower than about 40°C) and desorbs  t h e  0 2  
under h igh  tempera ture  (h igher  t han  about 80°C). So, when t h e  i n l e t  g : i ~  is in t roduced  i n t o  
t h e  Salcomine c a n i s t e r ,  t h e  inc luded  0 2  i s  absorbed by Salcomine. A f t e r  t h e  Salcoinine ab- 
so rbs  t h e  02,  t h e  Salcomine c a n i s t e r  i s  hea ted  and Salcoinine desorbs  0 2  of high p u r i t y .  
In  t h e  F ig .  3.1,  t h e r e  are t h r e e  (3) c a n i s t e r s  and each c a n i s t e r  i s  opera ted  i n  abso rb ing ,  
desorb ing  and p re -coo l ing  modes r e s p e c t i v e l y .  Thus, cont inuous  02 sepa ra t ing  ope ra t ion  
can be  c a r r i e d  out  by t h e  c y c l i c  exchange of t h e s e  ope ra t ion  modes. 
Functions of Oxygen Separa t ion  Systeni _- 
~ 
~ 
t h e  N 2  gas  b o t t l e .  Thus, i n l e t  g a s  i s  separa ted  i n t o  
3.2 SALCOMINE 
Fig .  3.2 shows t h e  s t r u c t u r a l  formula of t h e  Salcomine and i t s  02 abso rp t ion  and dcso rp t ion .  
/ 6 /  c a r r i e d  ou t  t h e  experimental  s tudy  on t h e  O2 absorb ing  and desorb ing  c h a r a c t e r i s t i c s  and 
t h e i r  v a r i a t i o n s  under repea ted  r e a c t i o n  of t h e  Salcomine, as a p a r t  o f  t h e  development of 
Di f fus ive  Atmosphere Control System (DACS, a kind of a r t i f i c i a l  g i l l ) ,  which e x t r a c t  O2 from 
sea wa te r  d i s s o l v i n g  oxygen. 
llie P resen t  s tudy  i s  based on t h e s e  r e s u l t s  and i s  designed t o  g e t  d a t a  t o  determine t h c  
o~)tirnuiii 0 2  s e p a r a t i n g  and concen t r a t ing  system f o r  CELSS. 
desorb ing  performance tests of Salcomine wi th in  t h e  c a n i s t e r  a r e  c a r r i e d  ou t  t o  g e t  t h e  d a t a  
t o  des ign  a compact, l i g h t  weiglit and lower energy consuming system. 
3 .3  Oxveen Abosrbine and Desorbine Tes t  of SALCObIINE 
There a r e  some s t u d i e s  on the  a p p l i c a t i o n  of Salcomine f o r  0 2  concent ra t ior i .  Cla tsutla 
In t h i s  s tudy ,  02 absorb ing  and 
3.3.1 Tes t  o f  SALCOMINE Proper .  I n  Fig.  3 . 3 ( a ) ,  oxygen con ta in ing  n i t rogen  gas i s  
in t roduced  i n t o  t h e  equipment and Salcomine absorbs t h e  0 2 ,  and i n c r e a s e s  i t s  weight.  And 
then  t h e  Salcomine is  hea ted  and t h e  Salcomine decrease  i t s  weight desorb ing  02. From t h e  
weight change of t h e  Salcomine, t h e  0 2  absorbed and desorbed i s  measured. 
T e s t  r e s u l t s  are shown i n  Fig.  3 .3 (b ) .  0 2  absorb ing  and deso rb ing  c a p a c i t y  o f  Salcomine is  
expressed  wi th  t h e  percentage  o f  oxygen weight t o  t h e  Salcomine. weight (wt%) .  
3 .3 (b ) ,  02 absorb ing  c a p a c i t y  i s  about 4.0 w t %  f o r  20% of 0 2  concen t r a t ion .  
From Pig .  
3 .3 .2  T e s t  o f S F C a l I N E  wi th in  C a n i s t e r .  
t h e  a i r  pump and in t roduced  i n t o  t h e  Salcomi 
absorbed  by Salcomine. 
In F ig .  3 .4 ,  0, 
.ne c a n i s t e r .  In t h c  
con ta in ing  a i r  i s  drawn by 
c a n i s t e r .  0 7  i n  t h e  a i r  i s  
(a) Tes t  Equipment (b) l e s t  I lesu l t s  
Reaction by SALCBIINE Fig.  3 .3  C h a r a c t e r i s t i c  Tes t  o f  SALCOPIINE 
Fig .  3 . 2  Oxygen Absorb and Desorb 
Proper  
69 
1,- "11.. 
Fig .  3 . 4  Diagram of C a n i s t e r  Contained 
SALCOFIINE Performance Test 
F ig .  3 .5  R e s u l t s  of  C a n i s t e r  Contained 
SALCON I NE Per f  orinanc e Tes t 
And a t  t h e  e x h a u s t  g a s  mani fo ld ,  02 c o n c e n t r a t i o n  i s  measured.  During t h i s  time, The 
Salcomine c a n i s t e r  i s  c o o l e d .  For  t h e  d e s o r b i n g  t e s t ,  t h e  c a n i s t e r  i s  h e a t e d  by hot w a t e r  
(90°C)  and drawn bv t h e  vacuum pump. 0 2  desorbed  from t h e  Salcooiine i s  c o l l c c t e d  i n t o  t h e  
sainpl ing  bag and  ana l  y s e d .  
F i g .  3 .5  shows t h e  r e s u l t s  of t h e  t e s t .  I n i t i a l l y ,  02 c o n c e n t r a t i o n  i n  t h e  o u t l e t  a i r  i s  
a lmost  0"; because  a l l  0 2  i n  t h e  a i r  i s  a b s o r b e d .  A f t e r  a few m i n u i t s ,  t h e  b r e a k - t h r o u g h  oc- 
c u r s  and 0 2  c o n c e n t r a t i o n  rises, and r e a c h e s  t o  21% which i s  equal  t o  t h a t  of t h e  i n l e t  a i r .  
From F i g .  3 . 6 ,  absorbed  02 i s  675CC and t h i s  cor responds  t o  2.7 w t o i  o f  02 a b s o r b i n g  c a p a c i t y .  
On t h e  s t a r t  of  0 2  d e s o r b i n g  t e s t ,  t h e  vacuum pump i s  o p e r a t e d  t o  purge  t h e  a i r  i n s i d e  t h e  
t es t  equipment .  The c a n i s t e r  is  then  h e a t e d .  And i s  drawn by t h e  vacuum pump. The drawn 
g a s  i s  measured 710 C C ,  and 02 c o n c e n t r a t i o n  i n  t h i s  gas  is  measured 51.4";. 
becomes 649 CC. 
So, desorbed  0 2  
4 .  CONCI,USION 
A s  a p a r t  o f  CELSS Cas Recycl ing  System Development, p r e l i m i n a r y  e x p e r i m e n t a l  s t u d i e s  were 
conducted f o r  t h e  p r o c e s s e s  of 0 2  r e c o r v e r y  from c o n c e n t r a t e d  COz and  o f  0 2  s e p a r a t i o n  and 
c o n c e n t r a t i o n  from exhaled  g a s  of  a n i m a l ,  p l a n t  e t c .  
S a b a t i e r  p r o c e s s  f o r  t h e  r e g e n e r a b l e  02 r e c o v e r y  from COz shows a good p o s s i b i l i t y  compared 
w i t h  Bosch p r o c e s s  i n  i t s  h i g h e r  e f f i c i e n c y  o f  Oz recovery  and easier h a n d l i n g  of  p r o d u c t  
carbon.  From t h e  02 s e p a r a t i o n  and c o n c e n t r a t i o n  t es t s  u s i n g  Sa icomine ,  oxygen a b s o r b i n g  
and d e s o r b i n g  c h a r a c t e r i s t i c  d a t a  a r e  o b t a i n e d  as t h e  fundamental  d e s i g n  d a t a .  
The above r e s u l t s  can b e  used  i n  t h e  p l a n n i n g  o f  a complete  and s t a b l e  g a s  r e c y c l i i l g  system 
r e q u i r e d  i n  CELSS. 
s i o n  of t h e  human f r o n t i e r  i n  Space.  
We hope t o  c o n t i n u e  our r e s e a r c h  and development  e f f o r t  f o r  t h e  expan- 
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Reduct ion of Carbon Dioxide i n  t h e  Bosch Process" ,  ASEIE Paper  No. 76-ENAs-7, J u l y ,  1976. 
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J u l y ,  1985. 
4 .  K .  O t s u j i ,  M .  I l i r a o ,  S.  S a t o u ,  "Concept S tudy  o f  Regenerable  Carbon Dioxide Reinoval and 
Oxygen Recovery System f o r  t h e  J a p a n e s e  Experiment Module", I A F / I A A - 8 5 - 3 0 5 ,  O c t .  1965. 
5 .  K .  N i t t a ,  81. Oguchi ,  S.  Kanda, "CELSS Experiment Model and Design Concept o f  G a s  Recycle  
System" SAE Technica l  Paper  No. 851393, J u l y ,  1985. 
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70 


Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

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