1. Introduction - Firenze University Press

Hydrate storage capacity was measured in CO2wt% (weight percentage) and in Nm 3 /m 3 (Nm 3 of gas
entrapped in 1 m 3 of hydrates), since these two parameters represent, in a macroscopic and
engineering approach, the capability of hydrates to entrap gases in their structure.
Results of experimental applications are reported in Table 1. Initial temperature is calculated as the
mean value of those measured in the lower and upper part of the reactor, before starting
recirculation and spraying.
Table 1. Results of experimental applications for CO2 hydrate formation.
Run T initial, Promotor Water spraying CO2 Wt% Storage
°C
time, min
capacity
Nm 3 /m 3
1 1.7 - 15 1.3 6.4
2 3.0 SDS 300
ppm
15 8.0 47.4
3 2.2 THF 1%wt 15 5.3 30.9
4 4.0 SDS 300
ppm
30 9.2 62.3
5 3.8 THF 1%wt 30 7.5 44.6
For comparison, a first experiment without additives was carried out (Run1). Results show that in
this case gas content is very small and the effect of gas solubility is not negligible.
Both SDS and THF promote formation of gas hydrates with a short reaction time, suitable for
industrial in-continuo applications (Run 2-3). Fig. 6 shows the picture of the hydrates formed in
Run 2.
Fig. 6. Carbon dioxide hydrates on the internal heat exchanger.
Gas storage increased of 15%, in case of SDS, and 41%, in case of THF, if the spraying time was
doubled (Run 4-5).
Gas storage capacity values are consistent with or rather greater - in case of SDS - than that
observed by other authors [9].
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