Hydrate formation during CO2 transport: Predicting water content in the fluid phase in equilibrium with the CO2-hydrate

In order to evaluate the risk of hydrate formation in CO2 transport one has to be able to predict the water content in the fluid phase in equilibrium with the CO2-hydrate. A literature review has identified some knowledge gaps, for example, there are no results available at temperatures lower than 243.15K (-30 degrees C); and none of the models found in literature predicts the water content with high accuracy. A model based on equality of water fugacity in fluid and hydrate phase is presented here and used for the predictions of water content in equilibrium with hydrates. Although this model gives better accuracy in the overall temperature and pressure ranges of measurements than the models found in the literature, it is not accurate enough to satisfy the requirements of CO2 transport. The simulation results also show that it is possible to form hydrate at low water content, such as x(w) = 50 vppm, if temperature is low enough. In order to verify the results and improve the model accuracy further, more experimental data in a larger temperature and pressure region are required. (C) 2010 Elsevier Ltd. All rights reserved.