Method and device for separating carbon dioxide from an exhaust gas of a fossil fuel-powered power plant

摘要

The method comprises burning a fossil fuel in a combustion process (1) to produce carbon dioxide-containing exhaust gas (2), contacting the carbon dioxide-containing exhaust gas with a first absorption medium in a pre-cleaning step (3) with a first absorption process (4) to absorb carbon dioxide by the absorption medium such that a first loaded absorption medium and a pre-cleaned exhaust gas is formed, which is partially free from carbon dioxide, and contacting the pre-cleaned exhaust gas with a second absorption medium in a final cleaning step with a second absorption process. The method comprises burning a fossil fuel in a combustion process (1) to produce carbon dioxide-containing exhaust gas (2), contacting the carbon dioxide-containing exhaust gas with a first absorption medium in a pre-cleaning step (3) with a first absorption process (4) to absorb carbon dioxide by the absorption medium such that a first loaded absorption medium and a pre-cleaned exhaust gas is formed, which is partially free from carbon dioxide, and contacting the pre-cleaned exhaust gas with a second absorption medium in a final cleaning step with a second absorption process to absorb carbon dioxide by the absorption medium such that a second loaded absorption medium and a cleaned exhaust gas are formed, which is free from carbon dioxide to a large extent. The gaseous carbon dioxide is delivered from the loaded absorption medium in a desorption process (8) to form a regenerated absorption medium. The gaseous carbon dioxide is thermally driven from the loaded absorption medium in the desorption process, and is delivered from the first loaded absorption medium in the pre-cleaning step in connection to the first absorption process with a first desorption process. The absorption medium is guided into a first circuit between the first absorption process and the first desorption process. The gaseous carbon dioxide is delivered from the second loaded absorption medium in the final cleaning step in connection to the second absorption process with a second desorption process. The absorption medium is guided into a second circuit between the second absorption process and the second desorption process. The absorption medium used in the first circuit is different from the absorption medium used in the second circuit. The absorption medium is a liquid such as fluid, gas, aerosol or suspension. A vaporizable solvent is used as fluid and is a solution made of water and amine derivatives. The heat from the regenerated absorption medium is removed from the circuits in a heat transfer process and is delivered to the loaded absorption medium from the first- or second circuit. The carbon dioxide separated from the exhaust gas is compressed, where the compressed carbon dioxide is stored. An independent claim is included for a fossil fuel-powered power plant.