This technology can be used to separate anode gases exiting a fuel cell at medium to high pressure. This invention is also applicable to exhaust gases of a similar composition from oxycombustion and chemical looping technologies. This technology achieves both efficiency improvement of power plants and carbon capture and sequestration by reducing the parasitic load required to capture and pressurize the CO2 (compared to the prior art), and by providing sufficient purification for pipeline transport to a geological sequestration site. This invention will be beneficial in power plant implementations, including those using a large variety of carbonaceous feedstocks such as coal, natural gas, and biofuels.
Existing methods to remove CO2 from fuel gases (such as solvent-based absorption, specially designed selective membranes, calcination, and condensing oxidation waste gases at low pressures) are often expensive, hazardous, or inefficient. Achieving CO2 purities as a supercritical fluid suitable for transport in a pipeline is also difficult. By using a multi-stage flash cascade in conjunction with multi-stage compression and condensation, this process will remove CO2 with high efficiency and high purities.
This invention describes a process for separating and capturing CO2 from water. A vapor stream containing CO2 and water is separated using a multi-stage flash cascade in conjunction with multi-stage compression and condensation. Additional cooling and flash steps can optionally be employed to help remove atmospheric gases such as nitrogen and argon from the feed. CO2 is condensed and pressurized to purities suitable for pipeline transport and eventual storage in geological formations, and water is recovered at high purity. Additionally, this power generation process incorporating the technique is shown to achieve high efficiency and zero emissions.
- More energy efficient separation with zero emissions
- Higher purity water
- No special solvents or membranes required
- Removal of incondensable gases such as nitrogen and argon