Patent PT-1953130-E (PT)
Title: Method and installation for raw gases containing processing methane and carbon dioxide, in particular biogas, for extracting methane
Inventor: GUENTHER LOTHAR
IPC: B01D53/00
Filed: 2007-01-30
Abstract: The method of treating biogas for extracting methane, comprises subjecting the raw gas under normal pressure or small negative pressure (50 mbar) in single or multi-stage wash (K01) with an amine containing washing solution with an amine concentration of 15% at normal temperature or at 100[deg] C under formation of clean gas flow consisting of methane and water, compressing the washing solution to 8-12 bar and then heating at 120[deg] C and 1-3 bar under a post-reaction duration of 280-1200 seconds and a constant reaction temperature, and cooling the cleaned washing solution below 50[deg] C. The method of treating biogas for extracting methane, comprises subjecting the raw gas under normal pressure or small negative pressure (50 mbar) in single or multi-stage wash (K01) with an amine containing washing solution with an amine concentration of 15% at normal temperature or at 100[deg] C under formation of clean gas flow consisting of methane and water and subsequently separating by cooling and condensation of the water or optionally recycling in the washing cycle, compressing the washing solution containing carbon dioxide and sulfur compounds to 8-12 bar and then heating at 120[deg] C and 1-3 bar under a post-reaction duration of 280-1200 seconds and a constant reaction temperature, and cooling the cleaned washing solution below 50[deg] C and then expanding in a second expansion stage (F03) on normal pressure. In the compression process, the predominant portion of carbon dioxide and sulfur compounds is separated from the washing solution and removed as gas flow. The existing residues at dissolvable carbon dioxide and sulfur compounds are separated and the cleaned washing solution is cooled to normal temperature and then recycled into the washing stage. During the multi-stage washing, more than 50% of the necessary quantity of washing solution is used in the first washing stage. The washing solution obtained in the washing is heated in two stages by indirectly heating heat exchanger (W02, W03) on the reaction temperature. The gas flow is led through two heat exchangers (W06, W07) turned in row, cooled on normal temperature and then supplied to a separator (F02), in which water condensed from the gas flow is separated and the water-free gas flow (carbon dioxide and sulfur compound) is exhausted in a pressure-regulated manner. The hot washing solution eliminated from the first expansion stage (F01) is used as heat distribution medium for the heat exchanger and is cooled down at 50[deg] C. The raw gas is heated at 20-60[deg] C and a pressure is adjusted to 20-150 mbar. In the first expansion stage (F01) over 95% of the portions of carbon dioxide and sulfur compounds is deposited. The gas flow separated from the first relaxation stage (F01) is desulfurized in a desulfurization plant. The washing solution is exposed to an ultrasound treatment during the first expansion phase (F01). An independent claim is included for a plant for treatment of biogas for extracting methane.