Rheological Properties of CO2 Hydrate Slurry Flow in the Presence of Additives

This work investigates the flow properties of CO2 hydrate slurry in dynamic loop in the presence of additives (surfactants, antiagglomerants) for use as two-phase secondary refrigerant. To be considered as suitable for refrigeration systems, the use of hydrate slurries must overcome instability phenomena such as hydrate particle agglomeration. The additives were employed in the present work to prevent this phenomena, and thus to improve the stability and the homogeneity of the fluid. A multicriterion approach was used to select additive and to define the optimal operating conditions for its use. The selected additive was an EO/PO block copolymer. The flow properties of CO2 hydrate slurry in aqueous media in the presence of this additive were then measured in an experimental loop. It was possible to model the rheological behavior of the CO2 hydrate slurry in the presence of EO/PO block copolymer by an Newtonian-type equation. The present results were compared to previous results obtained without additive. This article provides new information on CO2-hydrate slurry rheology, which is important not only in the development of hydrate-based refrigeration systems, but also in the field of flow assurance in oil and gas pipelines or for other applications such as gas purification and storage processes using clathrate hydrates.