Utilization of excess steam to provide refrigeration for cryogenic-based carbon dioxide removal systems
Publication Date: 2009-May-28
The IP.com Prior Art Database
Utilization of membrane water gas shift reactors for CO2 removal from syngas and FT tail gas
In converting synthesis gas to long chain paraffinic hydrocarbons, a Fischer-Tropsch based gas-to-liquids (GTL) plant generally exhibits both a poor thermal and carbon efficiency of around 60-70%. Therefore, in a carbon constrained world, GTL plants may be prime targets for greenhouse gas mitigation through carbon capture and sequestration involving the capture of large volumes of CO2 for long-term storage in underground geologic formations. Another characteristic of GTL plants is that there is a significant amount of excess medium pressure steam, since the remote locations of these plants make it economically infeasible to use this steam to produce power. In GTL plants, large volumes of unconverted gases, commonly called tail gases, are produced. The tail gases are either recycled back to the syngas generation step or they are used for fuel. In some circumstances, there is excessive tail gas. The gas cannot be recycled and the volumes that are available are higher than the fuel requirements. This tail gas normally contains high concentrations of CO2. This CO2 prevents recycling the tail gas back to the syngas generation step because it changes the key H2:CO ratio in the syngas, and it will build up in the syngas conversion step, resulting in lower reactant concentrations and lower conversion levels. The CO2 can be removed using conventional solvent absorption s...