Nuclear Production of Hydrogen, Fourth Information Exchange ...

CEA ASSESSMENT OF THE SULPHUR-IODINE CYCLE FOR HYDROGEN PRODUCTION
Figure 3: Pressure and temperature evolution in a low iodine
content liquid-vapour equilibrium measurement experiment
300
250
200
Temperature
Pressure
35
30
25
20
T (°C)
150
100
50
15
10
5
0
P (bar)
0
23/10/07
12:00
24/10/07
0:00
24/10/07
12:00
25/10/07
0:00
t (h)
25/10/07
12:00
26/10/07
0:00
26/10/07
12:00
-5
27/10/07
0:00
Table 1: Energy consumption of the I/S cycle
kJ/mol H 2
Heat Electricity
Bunsen section 000 04
Sulfur section 365 00
Iodine section 235 60
TOTAL 600 64
Feasibility
The sulphur-iodine cycle was demonstrated in Japan (Kubo, 2004), so there is little doubt it can indeed
continuously produce hydrogen. The question of its feasibility therefore only arises when related to
industrially acceptable conditions, both from the point of view of the efficiency and of the hydrogen
production cost. It is to address this question that the US DOE and French CEA teamed up to build an
Integrated Laboratory Scale experiment (Russ, 2009), with prototypical operating conditions that could
be extrapolated to a large scale production plant.
The status of this experiment is presented in another paper (Russ, 2009), and we just mention
two points here:
• The small scale (100 l H2 /h) which was chosen for the experiment turned out not to facilitate
the demonstration. Many technological solutions that could have been used with larger flows
and pipes were not available at such a small scale.
• Iodine handling appeared to require extreme care to avoid condensation and clogging.
In particular, it proved difficult to consistently and routinely melt and flow the pure iodine
which is fed to the Bunsen section. Special care must therefore be given to temperature
control in order to make sure all points remain above iodine melting point, including during
start-up and shutdown transients.
Aside from this experiment, several other feasibility questions have to be mentioned.
172 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010