Comprehensive capture technology for low-concentration carbon dioxide in industrial waste gases. For industrial waste gases with a carbon dioxide content of only about 10 to 60%, a series of carbon dioxide capture and concentration technologies have been developed to recover carbon dioxide from low-concentration gas sources. , combined with adsorption distillation refining technology, to make it meet national food grade standards and industrial gas standards.
Serialized carbon dioxide capture and concentration technology has the following three process methods:
1. Solvent absorption method: power plant boiler flue gas, steel plant smelting exhaust gas, lime kiln and cement In gas sources generated by combustion processes such as factory exhaust gas and ore decomposition gas, the carbon dioxide concentration ranges from 12 to 40%. A chemical composite solution developed for the above gas source (patent has been accepted), the raw material gas is fully contacted with the solution in the absorption tower, the carbon dioxide is absorbed by the reaction, and then heated and desorbed in the desorption tower, releasing a concentration of more than 96% Carbon dioxide is purified through adsorption distillation to obtain high-purity carbon dioxide products. For the pressured low-concentration gas source, a physical composite solvent is used to contact the raw gas in the absorption tower. After the carbon dioxide is dissolved, the carbon dioxide is released by reducing the pressure in the flash evaporation tower. High-purity carbon dioxide products can also be obtained. Among them, low-temperature methanol washing technology to recover carbon dioxide is a patented technology that is being widely promoted and applied.
2. Pressure swing adsorption method: For the conversion gas of chemical fertilizer plants, the carbon dioxide concentration must be removed between 12 and 20%. The pressure swing adsorption decarbonization technology is used, using strip activated carbon and spherical small holes. Silica gel is used as an adsorbent to enrich carbon dioxide to about 60% and then drain it. This decarbonization technology is only suitable for decarbonizing conversion gas and is not suitable for producing high-purity carbon dioxide gas products.
3. Catalytic combustion (catalytic oxidation) method: For carbon dioxide gas field gas, the content is between 83 and 89%, and the remaining 11% or so is saturated hydrocarbons mainly methane. Using catalytic oxidation method technology, Pure oxygen is added to burn off hydrocarbon impurities under the action of palladium carbon catalyst. This method requires adding excess pure oxygen to support combustion. The catalytic combustion must be operated above 300°C. The process is complicated and the energy consumption is high. There are also some non-combustible impurities such as sulfides that are difficult to remove. Therefore, in addition to gas field gas, other Gas sources generally do not use this technology.