Hydrate-based desalination process using CO2 as hydrate forming agent – Modelling and techno-economic analysis
Isabel S. Fernandes, Mariana G. Domingos, Marcelo Fernandes Costa, Ricardo J. Santos, José Carlos B. Lopes
Abstract
The potential of using CO 2 for hydrate-based desalination is evaluated in this work. CO 2 hydrate formation occurs in a device that uses the NETmix technology and is implemented and modelled in Aspen Plus. To ensure that the vapour-liquid and liquid-liquid equilibria are correctly estimated, the solubility of CO 2 in salt water under incipient hydrate formation conditions is predicted by different property models available in Aspen Plus and compared with published models based on experimental data. The energy and economic costs of the process are then assessed for two process flowsheets, which differ in the cold utility source. In one case, heat pump/refrigeration cycle technology integrates the heat from the hydrate formation and dissociation units, resulting in a Specific Energy Consumption (SEC) within the range of Multi-Stage Flash desalination technologies. In the other case, using the latent heat of natural gas regasification as a cold utility significantly reduced the costs, enabling the production of drinking water with an SEC in the same range as Reverse Osmosis. • Hydrate-based desalination process using CO 2 was modelled in Aspen Plus • Two cold utilities were considered: heat pump and the heat from LNG regasification • Hydrate-based process using a heat pump led to an SEC ~ 13.2 kWh·m −3 • Hydrate-based process using LNG cold utility reduces the SEC for 3.8 kWh·m −3 • This desalination technology is a cost-effective solution for water scarcity