Radiolytic-chemical method for production of gases

The invention disclosed provides a new improved radiolytic-chemical method for gas production by inclusion of oxide of nitrogen in the processing system to inhibit recombination of radiolytic products and to scavenge oxygen from the process stream. The present multi-step chemical and radiation method provides gases which may be used directly as fuel or as a base in production of hydrocarbon fuels.

BACKGROUND 
This invention relates to a new improved radiolytic-chemical method for gas 
production. More particularly, the present invention provides an efficient 
means for the improved production of gases useful for generation of fuels 
by inclusion in the radiolytic processing steps of predetermined amounts 
of oxide of nitrogen. 
One problem in the prior art when deriving oxygen from compounds including 
combustible fuels is that of scavenging the surplus oxygen. This general 
subject matter is set forth for example in copending application Ser. No. 
416,999 filed Nov. 19, 1973 by Robert J. Teitel. 
Radiolysis, that is, the molecular fragmentation or dissociation of larger 
molecules by radiation is a known phenomenon. One example of radiolysis is 
the formation of carbon monoxide and oxygen by radiolytic decomposition of 
carbon dioxide. Typically, however, such production of carbon monoxide and 
oxygen is low an commercially inefficient because of the great tendency of 
carbon monoxide to re-combine with the oxygen. 
A number of publications have considered use of oxides of nitrogen as means 
for inhibiting recombination of carbon monoxide and oxygen during 
decomposition of carbon dioxide by ionizing radiation. See for example, 
Chemonuclear Reactors and Chemical Processing, page 313, FIG. 19; P. 
Harteck et al., "Decomposition of Carbon Dioxide by Ionizing Radiation. 
Part II". J. Chem. Phys., 26, no. 6, 1727-33 (1957); A. R. Anderson et 
al., "The Radiolysis of Carbon Dioxide", Radiation Res. Rev. 1, 269-300 
(1968); and Steinberg "Radiation Processing Report No. 3", BNL 665 (T-219) 
(1961). 
OBJECTIVES AND BRIEF DESCRIPTION 
It has now been found, that by practice of the present invention there 
results a new improved method for radiolytic-chemical gas production. 
Oxides of nitrogen are used to prevent combination of the combustible 
fuels with oxygen during radiolysis. In addition they are useful in 
separating surplus oxygen from combustible fuel residual gases. The 
multi-step method is arranged such that, except for secondary losses such 
as by escape, evaporation, mutation and so forth, all chemicals, except 
for feed and product materials are completely recycled. 
Generally, the present method is based on the following chemical reaction 
sequence: 
##EQU1## 
Thus, carbon dioxide is dissociated to carbon monoxide and oxygen while in 
the presence of nitrogen dioxide. The carbon monoxide may then be reacted 
with water to form carbon dioxide and hydrogen. 
In the above reaction (III), the carbon dioxide can be recycled. The only 
feed material, namely water, is consumed through conversion to oxygen (I) 
and hydrogen (III). It will be appreciated that the heat needed for the 
thermochemical reactions can be derived directly from the fusion reaction 
or other high heat source as may be convenient. Reference is made to 
Advances in Nuclear Science & Technology, Vol. 1, P. 297, where a similar 
process has been reported in connection with fission energy sources. 
The radiation source used for practice of the present invention may include 
those conventionally used to effect radiolysis. Dissociation may be 
effected by neutrons, alpha, X or gamma radiation. Use of radiation from 
thermonuclear fusion reactions has a significant advantage over the use of 
radiation from fission reactions because of the efficient production of 
neutrons and the absence of severe contamination of the products by 
radioactive fission fragments and by the fuel particles. In fission 
reactions, direct exposure of the molecules is necessary because about 80 
per cent of the fission energy is contained in the fission fragments. In 
some cases, it is recognized however that fission energy such as gamma 
radiation or even some fast neutrons may prove useful without direct 
contact of the fission fragments with the materials being processed. 
In thermonuclear fusion of D-T, 80 percent of the energy is released as 
fast neutrons and the remaining 20 percent of the energy is released as 
alpha and X rays. In the fusion reaction, the material to be processed may 
be exposed directly to the radiation or may be exposed while being 
confined in a separate container. The latter condition is particularly 
appropriate for the neutron exposure since the neutrons have an effective 
penetration characteristic. 
Thus, the use of fusion devices, with the resulting high energy neutrons, 
as well as alpha and X rays, allows for the direct interaction of the 
radiation with the reactants while avoiding contamination with fission 
fragments. This difference alone is extremely significant in considering 
the use of thermonuclear reactors for chemonuclear processing by the 
present method. 
Practice of the present invention will become more apparent from the 
following detailed description taken in connection with the accompanying 
drawing wherein like numerals refer to similar elements.

DETAILED DESCRIPTION 
Referring to the block diagram of the accompanying FIGURE, radiolysis may 
be effected by exposing carbon dioxide (CO.sub.2) gas to a source of 
radiation (RS) while containing a stabilizing amount of an oxide of 
nitrogen. The amount of the oxide of nitrogen such as nitric oxide (NO), 
nitrogen dioxide (NO.sub.2) or the like varies from about 0.1% by weight 
to about 5% by weight based upon the amount by weight of carbon dioxide. 
Typically, the amount of the gaseous oxide of nitrogen varies from about 
0.5% to about 1.5% by weight with about 1% by weight being preferred. 
Carbon dioxide and, for example, nitrogen dioxide may be introduced into 
the radiation source RS via line 1 and after radiation exposure exits the 
source by line 2 for passage to steam generator 4, steam from which may be 
used to generate power in turbine 11. Condenser 6 is cooled by water 
passing lines 8 and 10 while being cycled by pump 12. 
In the illustrated method, the preferred embodiment of radiolytic 
conversion is effected by energy of a fusion reaction such as from 
deuterium-tritium (D-T) in pellet form. Although a number of different 
approaches are available, one that utilizes a source of energy from a 
laser and particular pellet configurations to achieve a fusion reaction in 
a reaction chamber is especially useful. Patents which illustrate 
generally the apparatus which can be used in this type of system include 
U.S. Pat. Nos. 3,378,446; 3,489,645; and 3,762,992. Also commercial 
neutron generators are currently available in the art, such as the Kaman 
generators, which may provide radiation energy. 
Because of the relatively low conversion rate of CO.sub.2 to CO and O.sub.2 
per pass, and the greater separation work required for a more dilute 
mixture of gases, a fraction of the gas, after heat removal in steam 
generator 4, is recycled via line 14. For example, about 3/4 of the gas 
from the steam generator may be recycled via line 14 to inlet line 1. 
Pumps can be used at convenient locations such as shown. 
Gases which are not recycled may be passed by line 16 to mixer 18. The 
oxygen in the gases is combined with nitric oxide (NO) via line 20 to form 
NO.sub.2 which simplifies the separation of hydrogen, carbon dioxide, 
carbon monoxide or other forms of combustible gases and oxygen. For 
thermal efficiency, heat generated within mixer 18 may be recovered for 
other uses including supply of thermal energy where needed in the 
processing system. 
The gas stream is next cooled in heat exchanger 22 which reheats CO.sub.2 
being recycled via line 24. Most of the NO.sub.2 is removed in condenser 
26 by counter-current flow of CO.sub.2 liquid which evaporates via lines 
28 and 30. Most of the CO.sub.2 and remaining NO.sub.2 is next separated 
in refrigeration unit 32. Liquid CO.sub.2 passes via line 28 to NO.sub.2 
condenser 26. The cold gas stream passes into NO.sub.2 absorber 36 via 
line 34. The NO.sub.2 absorber 36 removes the remaining NO.sub.2 from the 
cycling stream. Next, the gas mixture of CO.sub.2 and CO enters an aqueous 
K.sub.2 CO.sub.3 absorber unit 38 to effect removal of CO.sub.2. The gas 
leaving absorber unit 38 via line 41 contains about 1% by weight CO.sub.2 
with the remainder being CO gas. The CO.sub.2 removed is recovered and 
recycled to the heat exchanger 22 via lines 101 and 47. The gas mixture 
next proceeds to a water-gas shift reactor and H.sub.2 separation unit 42 
from which H.sub.2 gas results via line 44. CO.sub.2 from the H.sub.2 
separation unit is recycled in line 46. Also gases leaving water cooler 52 
are permitted to return to line 50. 
The recovered NO.sub.2, except for a small recycle 60, is fed to HNO.sub.3 
subsystem 54 by means of lines 56 and 58. In unit 54, the NO.sub.2 is 
permitted to react with azeotropic HNO.sub.3 to form concentrated 
HNO.sub.3 and regenerate NO for recycle in line 20. The concentrated 
HNO.sub.3 is decomposed at elevated temperature and pressure to form 
O.sub.2 which passes out by line 62. 
A number of positive features are apparent in the CO.sub.2 based cycle for 
producing hydrogen from water. For example, there is excess mechanical 
power capability. Also, the corrosion problems for most of the process are 
sufficiently mild that low alloy steel is a likely material of 
construction, except for unit 54. 
A representative flow balance for the present system is presented in Table 
1. 
Although the present method has been illustrated generally by diagram, it 
will be apparent to those of the art that many variations may be made 
therein without departing from the essence of the features disclosed 
herein. 
TABLE 1 
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Process 
Temp Pressure 
Flow Rates, Lb. Mole/Hr. (G = 10) 
Stream # 
.degree. F. 
PSIA CO.sub.2 
CO NO.sub.2 
NO H.sub.2 O 
H.sub.2 
O.sub.2 
Total 
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1 600 600 38,217 2,609 430 1,305 42,561 
2 1,200 600 37,389 3,438 430 1,719 42,976 
5 600 600 37,389 3,438 430 1,719 42,976 
16 600 600 9,011 829 103.6 414 10,357 
14 600 600 28,378 2,609 326.4 1,305 32,819 
24 600 600 9,839 103.6 9,943 
20 100 600 829 829 
19 610 600 9,011 829 808 124 62.1 10,834 
60 12 600 103.6 103.6 
50 148 600 9,839 9,839 
23 175 600 9,011 829 932 10,771 
30 43 600 7,548 7,548 
29 53 600 654 654 
27 53 600 9,011 829 278 10,118 
28 12 600 7,548 7,548 
57 12 600 254 254 
59 600 932 932 
34 12 600 1,463 829 24 2,316 
40 160 600 10.1 829 5.5 844.6 
48 95 600 1,453 1,453 
56 100 600 24 24 
58 12 600 829 829 
62 100 150 414 414 
37 80 600 829 829 
41 290 600 839 829 1,668 
44 100 600 829 829 
46 90 600 839 839 
47 95 600 2,292 2,292 
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