In the context of human society beginning to use fossil fuels represented by coal and oil in large quantities, carbon dioxide emissions have risen sharply, causing certain damage to the balance between the atmosphere and the biosphere. The resulting greenhouse effect has led to various living environment problems, which have posed a great threat to human survival. At a time when carbon dioxide emissions are increasing day by day, considering the development and utilization value of this gas, people have begun to explore the recycling of carbon dioxide as a carbon resource. Therefore, based on the description of several carbon dioxide separation and recovery technologies, its comprehensive utilization as a carbon resource is analyzed.
CO 2 Recovery and Liquefaction Plants Physical Absorption Method
Physical absorption method refers to the use of organic solvents to separate and absorb acid gas components under pressure according to the different solubility of components, and to achieve solvent regeneration by lowering the pressure, so it does not require too much regeneration energy. The key to the effective application of this method is to select high-quality absorbents. The quality standards are high boiling point, large CO2 solubility, non-corrosive, non-toxic and stable chemical properties. At present, the commonly used absorbents are cyclopentane, tributyl phosphate, propylene carbonate, methanol, and N-methylpyrrolidone.
The principle of this method is that CO2 in the raw gas shows a higher solubility in the absorbent, while the solubility of other gases is relatively small. CO2 is removed based on this physical difference. It is often used in solute gases with high partial pressure, absorption under high pressure and low temperature, and desorption under low pressure heating control. Low pressure heating is the most effective way to reduce energy consumption.
CO 2 Recovery and Liquefaction Plant Membrane separation method
The realization of membrane separation technology mainly depends on the different permeabilities of different components through polymer membranes. When facing gas crossing, the membrane made of polymer materials will achieve gas separation according to the difference in permeability. Pressure difference is the driving force of membrane separation. Only with the existence of pressure difference can gas components with higher permeability pass through the membrane and be separated in the form of permeation gas flow. Most gases with low permeability will stay on the air inlet side of the membrane.
The membrane materials currently used for CO2 membrane separation are mainly polysulfone membrane, cellulose acetate membrane, polypeptide membrane, polyethersulfone membrane and polyamide membrane, which are especially suitable for separating and recovering CO2 produced in the process of natural gas and oil mining. However, the heat resistance of these membranes is not very good. Although the heat resistance temperature of polyamide membrane itself has reached the maximum value of 300℃, it can only reach the maximum operating temperature of 50℃ in actual application due to the limitation of membrane component related materials. Since the structure of membrane separation device is relatively simple, the cost required is much lower than that of solvent absorption method, but the purity of CO2 gas obtained in the end is not high. We can try to combine the two separation and recovery technologies to form a fusion mode of fine separation and rough separation, reduce comprehensive energy consumption, and control investment costs.
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