CO2 capture and purification
method and device based on absorption
This method improves absorption devices, increasing their effectiveness. The well-known problem is the pollution (gasification) of absorbent with gaseous impurities. Impurities dissolved in absorbent pollutes the received gaseous mixture. The problem can be partially solved by degassing of the absorbent using the previously offered method of liquids purification. But the other solution is the offered multiple-absorption method.
The method is based on the different distribution of gaseous impurities in gaseous and liquid phases during absorption (in absorbent). During the absorption, the gaseous impurities are distributed in liquid/gaseous phases according to the ratio depending on the absorbent(liquid) type and pressure, and it can be taken as 10 or 0,1 for example. So if we make the absorption-desorption of the same gas portion several times, each time we will make the concentration of impurities 10 or more times less.
For example, if after the first absorption-desorption cycle we have 70% CO2 and 30% of impurities, then after second cycle we will have 97% CO2 and 3% impurities, and after the third cycle, we will have 99,1% CO2 and 0,9% of impurities. Then the product can be purified using other methods (for example by the previously offered degassing) or by this method.
The method can be optimised by:
- using of different absorbents in some cycles,
- and/or different pressure, temperature,
- and/or different additions to absorbents (such as soda). For example, in the first cycle, the absorbent with soda can be used. And in the other cycles, the other absorbents (sensitive to impurities removed in the first cycle) with lower pressure & temperature needed or just cheaper absorbent can be used;
- the absorbent can be purified (degassed) between absorption and desorption in some or every cycle using degassing method.