Browsing by Author "Yang, Congning"

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    Experimental And Simulative Studies For Evaluating Desorption Performance With Blended Amine Solvents In Post-Combustion CO2: Capture Systems
    (Faculty of Graduate Studies and Research, University of Regina, 2020-07) Yang, Congning; Tontiwachwuthikul, Paitoon; Idem, Raphael; Torabi, Farshid; Young, Stephanie
    Desorption is a very important process to liberate CO2 from CO2 saturated rich solution by adding thermal energy provided by a reboiler. This process should be studied very seriously for improving economic efficiency because fresh solvent for every cycle of capture is very expensive and also up to 70% high energy consumption is required for solvent regeneration procedure. The objective of this research was to evaluate the desorption performance using reactive aqueous MDEA/PZ blends and aqueous MEA/MDEA/PZ experimentally in a bench-scale packed column and compared with the benchmark aqueous 5M MEA solution in terms of cyclic capacity, rate of desorption, desorption efficiency, liquid-side mass transfer coefficient and regeneration energy. The ProMax simulation results were validated with the experimental results. Results showed that the desorption performance was ranked as 3M MDEA+2M PZ>2M MDEA+3M PZ>1M MEA+2M MDEA+2M PZ>5M MEA and it highly depended on the amine type and concentration. It was observed that higher MDEA concentration in the blends can produce more bicarbonate ions which helped to accelerate desorption process with lower regeneration energy consumption. On the contrary, the higher percentages of MEA could cause more regeneration energy due to the high thermally stable carbamate formation. Although PZ could improve the absorption performance significantly, it was not beneficial for the desorption process like MEA. The parametric sensitivity analysis was conducted by the full absorption- desorption process with Promax simulation by changing operating conditions including CO2 concentration in the flue gas, amine flow rate, flue gas flow rate and reboiler temperature. Results demonstrated that cyclic capacity, rate of desorption, desorption efficiency and liquid-side mass transfer coefficient were strongly impacted by the flow rate of flue gas, concentration of CO2 in the flue gas and flow rate of amine. The regeneration energy not only was dependent upon the molar ratio of each amine in the blends, but also highly influenced by amine flow rate and reboiler temperature. The initial cost assessment was simulated later for calculating CO2 capture cost by computing amine cost, pump electrical energy cost and regeneration energy cost with the target of 90% CO2 removal efficiency. Results revealed that the best choice of removing CO2 is 3M MDEA+2M PZ because it only costed $93.88/kg CO2 and it could save approximately 34.59% cost than 5M MEA with the lowest regeneration energy. It was also observed that regeneration energy cost was the most contributor in the operating cost.
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    Experimental Evaluation of Innovative Catalytic Heat Exchangers for Energy-efficient Amine-based Post-combustion CO₂ Capture Processes
    (Faculty of Graduate Studies and Research, University of Regina, 2025-04) Yang, Congning; Tontiwachwuthikul, Paitoon; Chan, Christine; Idem, Raphael; Choi, Phillip; Sema, Teerawat; Raina-Fulton, Renata; Ricardez-Sandoval, Luis
    This PhD research focused on enhancing CO2 desorption performance in post-combustion carbon capture processes by developing and optimizing catalytic heat exchangers. The guiding principle was to address challenges, including operational complexity and high energy consumption, while minimizing costly modifications to existing piping and infrastructure in pilot plants. The feasibility of novel aqueous piperazine-based biphasic solvents was initially investigated to reduce solvent flow rates and optimize heat exchanger size. Although these solvents demonstrated promising absorption and desorption performance, challenges such as high viscosities, suboptimal phase split ratios and low amine concentrations in the rich phase limited their applicability in the catalytic heat exchanger system. An innovative agitated jacket vessel with a coil heat exchanger (JVC-EX) was developed and experimentally validated. Compared to the conventional fixed catalyst bed desorber, the JVC-EX using benchmark MEA solvent and solid acid catalyst HZSM-5 achieved approximately 30% catalytic enhancement, a 50% reduction in catalyst demand, and a 22% decrease in energy consumption while maintaining excellent operational stability and flexibility. However, concerns emerged regarding catalyst durability due to mechanical stirrer-induced attrition, highlighting the need for further mechanical optimization. To address this limitation, a spouted bed and jet-flow catalytic heat exchanger (SBJ-EX) was introduced as a non-agitated alternative. The SBJ-EX demonstrated a 70% improvement in heat transfer efficiency compared to traditional plate heat exchangers and delivered excellent CO2 desorption performance at lower operating temperatures. Its spouted design effectively minimized catalyst attrition, ensured system stability, and enabled faster catalyst replacement, significantly reducing maintenance downtime. Both catalytic heat exchangers showed strong adaptability for integrating existing and new industrial-scale carbon capture systems. Overall, this thesis provided valuable insights into the design, operation, and optimization of novel catalytic heat exchangers, emphasizing their potential to drive the adoption of catalysts in commercial-scale carbon capture applications.