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Title:CO2 absorption into concentrated carbonate solutions with promoters at elevated temperatures
Author(s):Devries, Nicholas
Advisor(s):Wang, Xinlei
Department / Program:Engineering Administration
Discipline:Agricultural & Biological Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):carbon capture
Carbon dioxide (co2) capture
potassium carbonate
Abstract:As atmospheric carbon dioxide (CO2) emissions continue to increase, it becomes important to develop methods to capture CO2 from large emission sources such as power plants. The Hot Carbonate Absorption Process with Crystallization Enabled High Pressure Stripping (Hot-CAP), which employs a concentrated potassium carbonate/bicarbonate (PCB) aqueous solution as a solvent and a potassium carbonate/bicarbonate slurry for CO2 stripping, is a novel method to capture this CO2 more efficiently than conventional technologies. We focused on addressing the issue associated with a slow rate of CO2 absorption into a potassium carbonate/bicarbonate solution by using amine and amino acid promoters. We will conduct an initial screening study using a lab scale stirred tank reactor. Promoters which showed the most potential were tested on a bench scale, packed bed column to simulate real process conditions. Five different primary/secondary amines and three amino acid salts were evaluated as promoters for a concentrated 40 wt% potassium carbonate/bicarbonate solution using a batch stirred tank reactor. Using amino acids, absorption rate was improved compared to the unpromoted 40 wt% potassium carbonate/bicarbonate but was not sufficiently high for the practical purpose. Amine promoters increased absorption rates into potassium carbonate/bicarbonate solution at 70°C by 3.5 to 50 times, with piperazine (PZ) and aminomethyl propanol (AMP) showing the highest promotion rate. Compared to the 5 M monoethanolamine (MEA) solution at 50°C (typical absorption temperature in benchmark MEA process), the absorption rates into the potassium carbonate/bicarbonate solution promoted with 1 M PZ and 1 M AMP at 70°C (typical absorption temperature in Hot-CAP) were higher or comparable either at CO2 lean or rich conditions. As determined by testing of CO2 absorption in a bench scale, packed bed column, use of selected rate promoters increased the rate of CO2 removal into potassium carbonate/bicarbonate solution. The 40 wt% potassium carbonate/bicarbonate solution promoted with 0.5 M PZ, DEA or AMP tested at 70°C performed 1 to 3 times better than 5 M MEA at 50°C at their respective lean loading levels and 3 to 5 times better at rich CO2 loading levels, when other conditions were the same.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Nicholas Devries
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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