https://doi.org/10.1016/j.ijggc.2022.103597
“The validated model from Section 2.3 was applied to a commercial-scale PCC process integrated with a natural gas combined cycle (NGCC) power plant. The condition of the combustion gasses entering the PCC system was set following typical composition Feron et al., 2020) with the gas flow rate modelled after a ∼650 MW gross electrical output NGCC power plant (Zoelle et al., 2015). Table 5 summarizes the combustion gasses conditions used in this study. Table 6 shows the configurations for the absorber and the stripper, and the operating conditions for the process. A structured packing (Mellapak 250Y) was used for both columns as recommended by IEAGHG (2012). The column diameter was determined so that the flooding factor was within 80%. Since a single train was used for absorber and stripper in this simulation to simplify the calculation, the column diameter, especially for the absorber, might be large relative to the height of the column. Though combustion gasses are supposed to be divaricated and treated with multiple trains in the commercial-scale real-world PCC, such a ramification is not associated with the main examination in this study and thus not considered. The heat exchanger between the rich and the lean solution was modelled with the heat exchanger module in Aspen Plus® (‘HeatX’). In HeatX, the product of the overall heat transfer coefficient (U) and the heat transfer area (A) must be specified. The heat transfer area was fixed at 18,000 m2 based on a plate-and-frame exchanger (PHE) (Lin, 2016). The overall heat transfer coefficient was calculated considering the effects of physical properties of the solution by using Eq. (17). The heat transfer coefficients of hot side (hh) and cold side (hc) were calculated by Eq. (18). In Eq. (18), k is the thermal conductivity of the fluid, De is the hydraulic diameter, and Nu is the Nusselt number. The Nusselt number was calculated using an empirical correlation for PHE using the Reynolds number (Re) and Prandtl number (Pr) as shown in Eq. (19) (Talik et al., 1995). The fluid velocity (u) was calculated considering the geometry of the heat exchanger by Eq. (20). In Eq. (20), L is the mass flow rate of the fluid, ρ is the fluid density, and l is the total flow length. The physical properties of solution relevant to Eqs. (17)–(20) were given as the average between the inlet and outlet conditions.
Table 5. Combustion gasses condition in commercial scale process simulation.
| Composition volume % | Mass flow rate kg/s | ||||
|---|---|---|---|---|---|
| N2 | CO2 | O2 | H2O | Ar | Empty Cell |
| 75.5 | 4.3 | 12.2 | 7.2 | 0.9 | 1029.31 |
Table 6. Configurations for the absorber and the stripper, and operational conditions in commercial scale process simulation.
| Empty Cell | Units | Value |
|---|---|---|
| Packing height (absorber/stripper) | m | 30/30 |
| Column diameter (absorber/stripper) | m | 22/10 |
| Packing type (absorber/stripper) | – | Mellapak 250Y/ Mellapak 250Y |
| Liquid temperature at the absorber inlet | °C | 40 |
| Gas temperature at the absorber inlet | °C | 40 |
| Liquid temperature at the stripper outlet | °C | 120 |
| Absorber pressure | kPa | 101.325 |
| Stripper pressure | kPa | Adjusted |
| Liquid-to-gas ratio | kg/kg | 0.81, 0.88, 1.15 |
In the sensitivity analysis, the inlet conditions of combustion gasses shown in Table 5 remained unchanged. The liquid flow rate was varied corresponding to the L/G in Table 6. By adjusting the pressure of the stripper according to the change in the liquid flow rate, the temperature at the bottom of the stripper was fixed at 120 °C. The CO2 capture rate was held constant at 90% by adjusting the reboiler duty.”
