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Crystals 2018, 8(1), 39; https://doi.org/10.3390/cryst8010039

CO2 Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber

Department of Chemical and Materials Engineering, Lunghwa University of Science and Technology, Taoyuan 33306, Taiwan
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Received: 21 November 2017 / Revised: 9 January 2018 / Accepted: 12 January 2018 / Published: 16 January 2018
(This article belongs to the Special Issue Carbonates)
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Abstract

A lab-scale bubble-column scrubber is used to capture CO2 gas and produce ammonia bicarbonate (ABC) using aqueous ammonia as an absorbent under a constant pH and temperature. The CO2 concentration is adjusted by mixing N2 and CO2 in the range of 15–60 vol % at 55 °C. The process variables are the pH of the solution, temperature, gas-flow rate and the concentration of gas. The effects of the process variables on the removal efficiency (E), absorption rate (RA) and overall mass-transfer coefficient (KGa) were explored. A multiple-tube mass balance model was used to determine RA and KGa, in which RA and KGa were in the range of 2.14 × 10−4–1.09 × 10−3 mol/(s·L) and 0.0136–0.5669 1/s, respectively. Results found that, RA showed an obvious increase with the increase in pH, inlet gas concentration and gas temperature, while KGa decreased with an increase in inlet gas concentration. Using linear regression, an empirical expression for KGa/E was obtained. On the other hand, ammonia bicarbonate crystals could be produced at a pH of 9.5 when the gas concentration was higher than 30% and γ (=Fg/FA, the gas-liquid molar flow rate ratio) ≥ 1.5. View Full-Text
Keywords: ammonia bicarbonate; carbon dioxide; mass-transfer coefficient; capture; bubble-column scrubber ammonia bicarbonate; carbon dioxide; mass-transfer coefficient; capture; bubble-column scrubber
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Chen, P.C.; Yu, S.C. CO2 Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber. Crystals 2018, 8, 39.

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