Novel Postcombustion Capture Process for CO₂ from the Flue Gas of Coal-Fired Power Plants Using a Green Deep Eutectic Solvent

Abstract

Green, efficient, and low energy consumption capture of CO 2 from the flue gas of coal-fired power plants has been one of the most popular research topics in the world. In this work, a concept process of postcombustion capture (PCC) using a choline chloride/urea (1:2) deep eutectic solvent (DES) as a physical solvent was proposed. The DES-based PCC process is modeled and simulated using commercial Aspen Plus simulation software. The required parameters were studied and further embedded in Aspen Plus. The simulation results show that the process has a good capture effect; the capture ratio of CO 2 is 97.33%, and the purity of CO 2 in the product gas is 99.42%. Through sensitivity analysis, the influence of several key parameters on the process performance is studied and reasonable operating conditions are determined. Exergy analysis is carried out for a CO 2 absorption unit and a solvent regeneration unit. The results show that the total exergy efficiency of these two units is 74.28%. The new DES-based PCC process has great potential and will provide a new way to capture CO 2 in the flue gas of coal-fired power plants.

Comprehensive Evaluation of a Deep Eutectic Solvent Based CO2 Capture Process through Experiment and Simulation

“…Process Design and Optimization. On the basis of the research of Wang et al, 43 the process flow sheet of the DESbased PCC CO 2 capture is shown in Figure 8. As shown in Figure 8, the flue gas first enters the separator to remove water, and then the dehydrated flue gas is mixed with the gas from the flash tank (Flash1) and enters the multistage compressor (MCompr, five stages) together to be compressed.…”

“…This is due to the fact that low pressure causes a large desorption of CO 2 , affecting the recovery rate of CO 2 , while high pressure causes insufficient O 2 and N 2 desorption, influencing the purity of CO 2 in the product gas. 43 Therefore, the pressure of Flash1 is set to 10 bar to meet the requirements: namely, a purity of CO 2 in the product gas of >90% and a recovery rate of CO 2 of >90%. In contrast to the pressure, as shown in Figure 10b, low temperature leads to insufficient CO 2 and N 2 desorption, while high temperature causes a large desorption of CO 2 .…”

“…Due to the lack of experimental data, the vapor−liquid equilibrium data of DES + O 2 and DES + N 2 were estimated by using the COSMO-SAC model, and the estimated data were further substituted to the binary interaction parameters of the thermodynamic model. 43 Life Cycle Assessment. The environmental sustainability of the DES-based PCC process was evaluated and compared with that of the MEA-based PCC process by life cycle assessment (LCA), which is in accordance with the guidelines of the ISO 14040/14044 standards.…”

“…The temperature-dependent correlation parameters, such as the liquid molar volume and dynamic viscosity of DESs, were determined experimentally, and the heat capacity and surface tension were calculated by the generalized model proposed by Taherzadeh et al and the generalized model proposed by Haghbakhsh et al, respectively. Due to the lack of experimental data, the vapor–liquid equilibrium data of DES + O 2 and DES + N 2 were estimated by using the COSMO-SAC model, and the estimated data were further substituted to the binary interaction parameters of the thermodynamic model …”

Simulation of a Depropanizer Distillation Column and Validation of Results by Industrial Data

“…The initial design with the equilibrium model for the DDC shows that the calculated diameter for the first part of the column is 1.23 m, while the second part is 1.78 m. Of course, the obtained values for the diameter of each part are used as the first estimate in the non-equilibrium model. Consequently, the new values of diameters are corrected and get closer to the real industrial values using the nonequilibrium model[31][32][33][34]. The mechanical specifications of the DDC for the first and second parts of the column are presented in rows 4-10 and 4-8 of Tab.…”