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CaBr 2 HYDROLYSIS FOR HBr PRODUCTION USING A DIRECT SPARGING CONTACTOR
Results and discussion
In the initial phase of the test programme, shake-down tests were performed to study the behaviour
of the melt phase; evaluate compatibility of materials, controls and safety; and validate the HBr
capturing process. The analysis of the NaOH solution showed that calcium bromide was not carried
over by flowing product gases as vapour and/or by entrainment. Over the course of the reaction for
each test run, the molten reagent CaBr 2 with the CaO product maintained a single phase, consistent
with the anticipated behaviour of the molten eutectic composed of CaBr 2 /CaO that formed as the
molten reagent CaBr 2 was consumed. The quartz glass proved to be unsuitable for hydrolysis in any
zone where the bath and steam were in contact, while commercial alumina and silicon carbide were
practical and showed no evidence of corrosion or surface degradation after being cycled through these
experiments. The experiments show that both alumina and SiC are compatible with the melt
although SiC seems to plug more readily. Details around the test apparatus showing the original
funnel-design quartz glass sparger are attractive concepts (Figure 3), but all reported runs employed a
non-funnel straight tube.
Figure 3: Sparger assembly showing funnel concept
Test conditions are presented in Table 1, which has been organised from highest to lowest
bromine accumulation rates in the NaOH capture solution. These do not reflect the actual run order.
All tests were performed at atmospheric pressure. Figure 4 shows bromine as a function of reaction
time for all the tests. After the steam feed was shut off the furnace kept the melt at the reaction
temperature while an argon flow through the apparatus swept any uncollected bromine into the
NaOH bath. The sample collected at the end of this sweep appears as the final data point in Figure 4
for each test.
274 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010