https://doi.org/10.3390/su14127095
“The chemical concentration is one of the most concerning parameters that may possibly affect the removal performance. To observe the influence of the chemical concentration on the process performance, different blends of PZ + AMP were prepared by maintaining the PZ concentration at 7 wt.% and added to 3, 13, 23, and 33 wt.% concentrations of AMP. Hence, the chemical concentration was tested in the range from 10 to 40 wt.%. The gas and liquid phases were constantly supplied to the column at flow rates of 26.52 kmol/m2∙h and 4.33 m3/m2∙h, respectively. The variations in the chemical concentration and Lamine/GCO2 ratio that were analysed in the current experimental work are shown in Table 5. It can be seen that the Lamine/GCO2 ratio increased as the amine concentration increased.”
| Chemical Concentration (wt.%) | CO2 Flow Rate (GCO2) (kmol/m2 h) |
Total Liquid Flow Rate (kmol/m2∙h) | Amine Flow Rate (Lamine) (kmol/m2 h) | Lamine/GCO2(kmol/kmol) |
|---|---|---|---|---|
| 10 | 10.61 | 15.84 | 5.33 | 0.50 |
| 20 | 10.61 | 15.84 | 10.44 | 0.98 |
| 30 | 10.61 | 15.84 | 15.37 | 1.45 |
| 40 | 10.61 | 15.84 | 20.26 | 1.91 |
“Figure 9 shows that an increase in the chemical concentration from 10 to 40 wt.% can lead to respective increments in the CO2 removal performance from 33% to 100% at the exit of the column. By observing the trendline for the blended solution containing 40 wt.% PZ + AMP, a significant increase was observed at the column height from 0 to 1.02 m, followed by a steady increase beyond the 1.02 m section to achieve 100% removal. A high absorption percentage was observed at the bottom section of the column (0 to 0.68 m), in which approximately 56% of the CO2 molecules in the gas stream were absorbed by the absorbent. The remaining 18% of CO2 in the gas phase travelled upwards in the column, where the CO2–amine reaction began to decrease due to the decreased CO2 concentration in the gas phase. Hence, within the middle section of the column (0.68 to 1.36 m), this system was able to remove 37% more CO2 from the gas stream. This system achieved 100% CO2 removal at the column height of 1.70 m. Hence, it was concluded that the blended solution containing 40 wt.% PZ + AMP (Lamine/GCO2 ratio = 1.91) demonstrated excellent CO2 removal within 83% of the column height.”
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“Apart from the higher process performance at a higher amine concentration, the increase in viscosity as the amine concentration increases needs to be considered, as it could possibly hinder CO2 diffusion across the gas to liquid film [64]. It could also reduce mass transfer performance due to the reduced effective area of the absorbent on the packing surface. Furthermore, the high amine concentration could also contribute to processing equipment corrosion. Therefore, an optimal chemical concentration is vital for the potential absorbent to be applied as an industrial absorbent.”