Performance of an Electrified Hot Potassium Carbon Capture System under Varying Operating Conditions
Author
Jeppesen, Mads Bluhme
Term
4. term
Education
Publication year
2025
Submitted on
2025-09-22
Pages
48
Abstract
Dette speciale undersøger et punktkilde-kulstoffangstsystem, der bruger varmt kaliumcarbonat (HPC) til at fjerne CO2 fra røggas, baseret på CapSols End-of-Pipe-design. Systemet blev modelleret i procesprogrammet Aspen Plus V12.1 som en hastighedsbaseret, stationær model (hastighedsbaseret betyder, at reaktions- og masstransporthastigheder beregnes i stedet for at antage fuld ligevægt; stationær betyder, at forholdene ikke ændrer sig over tid). Modellen blev valideret ved at sammenligne reaktionsligevægten med forsøgsdata; afvigelsen var 14–17 %, og den højeste simulerede temperatur i reaktionszoner var cirka 120 °C. Formålet var at finde de driftsbetingelser, hvor HPC yder bedst, og at give nøgletal, der gør det lettere at sammenligne med andre kulstoffangstsystemer. Resultaterne indikerer, at anlægget kan drives med elektrisk energi og køleforsyning (samt lidt makeup-vand og absorbent), med et specifikt forbrug på cirka 915 kJ/kg CO2 el og 993 kJ/kg CO2 køling ved 24 vægt% CO2 (ca. 16 mol%) i røggassen. Ydeevnen falder markant ved lavere CO2-koncentrationer. Derudover blev det undersøgt, hvordan trykket i regeneratoren (hvor CO2 frigives), absorberen (hvor CO2 optages) og lean flash-beholderen (en trykaflastningsbeholder) påvirker systemet, samt hvor følsom fangstgraden er over for ændringer i flash-beholderens tryk.
This thesis studies a point-source carbon capture system that uses hot potassium carbonate (HPC) to remove CO2 from flue gas, based on CapSol’s End-of-Pipe design. The system was modeled in the Aspen Plus V12.1 process simulator as a rate-based, steady-state model (rate-based means it calculates reaction and mass-transfer rates rather than assuming equilibrium; steady-state means conditions do not change over time). The model was validated by comparing the reaction equilibrium to experimental data; it differed by 14–17%, and the peak simulated temperature in reaction zones was about 120 °C. The goal was to identify operating conditions that give the best performance and to report metrics that make comparisons with other capture systems easier. The results indicate the unit can run on electric power and a cooling utility (plus some makeup water and solvent), with specific energy use of about 915 kJ/kg CO2 electricity and 993 kJ/kg CO2 cooling at 24 wt.% CO2 (≈16 mol%) in the flue gas. Performance drops significantly at lower CO2 concentrations. The study also examined how the pressures in the regenerator (where CO2 is released), absorber (where CO2 is captured), and lean flash box (a pressure-reduction vessel) affect the system, and how the capture rate responds to changes in flash-box pressure.
[This summary has been rewritten with the help of AI based on the project's original abstract]
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