A continuous production of gas hydrates is the route proposed for the CO2 capture and separation.Gas hydrates are crystalline solid materials similar to ice crystals, wherein non-polar small molecules, such as CO2, CH4, N2 H2, and other small hydrocarbons are trapped. The solid crystals are essentially cages of water molecules linked by hydrogen bonds. The formation of hydrates typically results in a volume reduction, which for the CO2 case is about 170 times smaller than that occupied at Normal Temperature and Pressure (NPT) conditions. The solid hydrates can be quite stable at ambient pressure and cold temperatures (0-10 °C), as long as they are well isolated from thermal energy sources to avoid the reverse gasification process. This drastic reduction in CO2 volume enables the storage and transportation of these gases at nearly atmospheric pressures in the form of an icy material at mild freezing temperatures. This is an alternative mean of transportation and long-term storage of CO2 from flue gases of power plants, but also from oil and gas exploration platforms. Another potential application also includes the re-injection of CO2 into the oil reservoirs for EOR.
Continuos production of CO2 hydrates.
The crystals formation/growth step is strongly exothermic, and temperature control is a key production constraint. The efficiency of hydrates production is intrinsically linked to difficulties on gas-liquid poor heat/mass transfer rates; mixing intensity for promoting crystallization; and subsequent precipitation/separation of hydrates.
In NET4CO2, the production of such hydrates is implemented by strongly mixing the gas streams with water, in the NETmix* technology, under the previously mentioned favorable conditions of temperature and pressure.
The continuous production of a CO2 hydrates has been successfully demonstrated at lab (1 kg/h of CO2) and pilot scale (10 kg/h of CO2). Production of units capable of producing 1 ton/h of CO2 is planned for the near future.
* PAT No. 103072 UNDER LICENSE OF FLUIDINOVA, S.A.