## 3 Model Development
### Steady-State Model Development
#### 3.2.6 Stripper Design  
After being heated, the rich amine enters the stripper, where the stripper is designed as a packed column tower. The top stream leaving the stripper goes into a condenser to condensate the water present in the vapor stream and to cool it down before being separated in a flash drum. The reflux pure water stream was recycled back to the stripper acting as a water wash to remove any entrained MEA that might be leaving as vapor. The CO\({}_{2}\) with a mass fraction of 0.99 was sent to the compression stage for further utilization. The operating pressure of the stripper was higher than the absorber (1.7 bar), as higher pressures in the reboiler entail higher temperature, which is more favorable for the liberation of the CO\({}_{2}\) and requires less steam to maintain the driving force. Nevertheless, the operating conditions were limited by the degradation of the MEA solvent at elevated temperatures [11]. Steam from utilities provides the required heat duty in the reboiler, which can be divided into three main requirements: (1) sensible heat to raise the rich amine temperature to the stripper temperature, (2) required heat of reaction to release the CO\({}_{2}\) component from the rich amine stream (reverse absorption), (3) heat to produce steam that would ensure a driving force for the release of CO\({}_{2}\) from the liquid phase to the vapor phase. At the elevated temperatures present in the stripper, the partial pressure of CO\({}_{2}\) (\(p_{\text{CO}_{2}}\)) over MEA is much higher, thus reversing the process of absorption.  
Two fundemental criteria had to be taken into account while designing the desorber column, the purity of the CO\({}_{2}\) stream has to be \(>\)98%, and the lean loading of the amine stream leaving at the bottom of the desorber had to match that of the lean amine entering at the top of the absorber with a value of 0.2. The lean loading values have to match for the model to converge once the solvent loop is closed. The Design spec tool was utilized to run several iterations with various heat duties until the loading was adjusted at a duty of 45,177 kW, while maintaining the purity of \(>\)98% CO\({}_{2}\) in the top stream. The lean amine stream leaves the reboiler with a temperature of 122 \({}^{\circ}\)C and exchanges heat with the incoming rich amine in the cross heat exchanger, as previously discussed. The outlet stream cools down to 67 \({}^{\circ}\)C, and a further cooler was required to lower the temperature to 40 \({}^{\circ}\)C to match the absorber operating conditions. A make-up amine stream was added to compensate any lost solvent through the process vent and CO\({}_{2}\) product steams. The balance tool in Aspen flowsheeting options was used to calculate the solvent and water make-up streams to avoid any imbalances, as also suggested by [PERSON] et al. [41]. In the actual process, a solvent reclaimer will be necessary to treat some of the heat-stable salts that are formed during operation, usually with a strong alkali and heat application [11]. Ignoring such a unit would lead to a lower solvent capacity by time reducing the efficiency of the process. Table 2 summarizes the Absorber-Stripper design parameters used in the model: