Method and system for recycling carbon dioxide from biomass gasification

摘要

A method for recycling carbon dioxide from biomass gasification. The method includes: 1) employing carbon dioxide as a gasifying agent, allowing the carbon dioxide to gasify biomass to yield syngas; 2) cooling the syngas; 3) introduced cooled syngas to a cyclone separator and a gas scrubber for dust removal and purification; 4) allowing purified syngas in 3) to react with the vapor to modify a ratio of hydrogen to carbon monoxide of the syngas; 5) desulfurizing modified syngas to remove H2S and COS therein; 6) decarburizing desulfurized syngas to separate carbon dioxide therein; 7) introducing desulfurized and decarburized syngas to a synthesizing tower to yield oil products and exhaust gas including carbon dioxide; 8) decarburizing the exhaust gas including carbon dioxide and separating the carbon dioxide; and 9) introducing the carbon dioxide separated in 6) and 8) to 1) as the gasifying agent for gasification.

主权项

1. A method of biomass gasification by utilizing carbon dioxide as a gasifying agent, the method comprising:
1) allowing the carbon dioxide to gasify biomass in a gasifier in the presence of external energy, whereby yielding syngas comprising CO, CO2, CH4, H2, H2O, H2S, and COS; 2) cooling the syngas from 1) in a primary heat exchanger by using carbon dioxide as a cooling medium, whereby the carbon dioxide is heated by the syngas to a temperature of between 350 and 600° C.; 3) cooling the syngas from 2) in a secondary heat exchanger by using water as a cooling medium whereby producing water vapor; 4) feeding carbon dioxide from 2) to the gasifier; 5) introducing the syngas from 3) to a cyclone separator and a gas scrubber for dust removal and purification; 6) contacting the syngas from 5) with the water vapor so that part of carbon monoxide in the syngas reacts with the water vapor to produce hydrogen and carbon dioxide; 7) removing H2S and COS from the syngas from 6) to obtain a desulfurized syngas; 8) removing carbon dioxide from the desulfurized syngas to obtain a desulfurized and decarburized syngas; 9) introducing the desulfurized and decarburized syngas to a synthesizing tower, wherein the desulfurized and decarburized syngas is catalyzed to yield oil and exhaust gas comprising carbon dioxide; 10) separating carbon dioxide from the exhaust gas from 9) to obtain an effluent gas free of carbon dioxide, and discharging the effluent gas; and 11) introducing the carbon dioxide obtained in 8) and the carbon dioxide obtained in 10) to the primary heat exchanger as the cooling medium.