- Multi-step process
There are several steps involved in post-combustion capture. These are outlined in the following. We have the expertise to fine-tune and customise each of these steps to optimise overall system performance – maximising the capture rate and energy efficiency of the process flow.
- Gas pretreatment
Hot flue gas is fed to the PCC plant, where it first enters the pH-controlled Direct Contact Cooler (DCC). In addition to cooling the flue gas, the DCC also removes sulfur dioxide to prevent the downstream amine loop from forming particulates. If necessary, an additional module for removing fine particles/aerosols can be included in the DCC to mitigate amine losses at the top of the absorber column.
After the DCC, the flue gas flow is pressurised by the flue gas blower to overcome the pressure drop of the entire absorber column.
- CO₂ absorption
After leaving the blower, the flue gas is fed to the bottom of the absorber column where CO2 is removed by a liquid aqueous amine in a counter-current flow. High-performance packing is installed in order to ensure efficient mass transfer and to minimise the column diameter and pressure drop. Due to the absorption enthalpy, the temperature in this section increases and this has the effect of lowering the process efficiency overall. A gravity-driven interstage cooler is installed between the absorption beds in order to increase the general performance of the plant. The upper section of the absorber column features the advanced emission control system.
The hot, rich solution enters the upper section of the desorber column and flows downwards counter-current to the vapour, which is generated in the reboiler. CO2 is stripped off the amine solution at this stage. After leaving the desorber column, the CO2 stream saturated with water is cooled in the overhead condenser. Condensate and CO2-rich gas are separated in the reflux drum and the condensate is fed back to the desorber column. Steam is used to provide the regeneration heat in the reboiler. The hot steam condensate is sent back to battery limit.