Abstract
The performance of a 4-bed/16-step vacuum swing adsorption cycle containing three pressure equalization (PE) steps has been analysed in order to understand the role played by the multiple PE steps in the process performance. The cycle was designed for CO2 capture from a feed gas mixture of 15 %CO2/85 %N2, with zeolite ×13 adsorbent from UOP (PSO2HP). Simulations were performed with the help of the commercial Aspen Adsorption simulator to help interpret the experimental results. It was found that CO2 loading decreased only slightly, but N2 loading decreased significantly and uniformly across the bed after each PE step. Thus, while CO2 working capacity remained almost constant, working selectivity and CO2 product purity increased with the number of PE steps. An experimental purity of 91.3 mol% CO2 could be obtained at a recovery of 77 % at 3 kPa desorption pressure, with a cycle containing 3 pressure equalisation steps. Specific energy consumption (calculated with a constant pump efficiency of 70 %) was calculated as 0.3 MJ/kg CO2, which was lower than the 1 and 2 pressure equalisation cycles. We evaluated 2-bed and 3-bed cycles containing one and two pressure equalisation steps respectively, by means of simulation in order to compare their performance with the base 4-bed 3PE cycle. For a constant recovery of 75–77 %, CO2 product purities increase by 7.4 and 4.2 % (relative) in going from 1PE, to 2PE and 3PE cycles respectively, at an evacuation pressure of 3 kPa. Specific energy consumption also decreased with the number of PE steps, owing to the lowering of the starting pressure for desorption and some savings in repressurization energy with the number of PE steps. The specific energy dropped by 13 % in going from 1PE to 2PE and 3PE steps. However, the extra beds and extra cycle time required for the 3PE steps led to a reduction in productivity by almost 33 % in going from the 2PE to 3PE cycles. The choice for including additional PE steps therefore relies on the tradeoff of capital and operating costs which is strongly location and project specific.
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References
Ackley, M.: Application of natural zeolites in the purification and separation of gases. Microporous Mesoporous Mater. 61, 25–42 (2003)
Aspen, 2011. Aspen adsorption v8.0 user help file. Aspen Technologies, Inc. (WWW Document)
Benkmann, C.: Six adsorber pressure swing adsorption process. US Patent 4,834,780 (1989)
Bird, R.B., Stewart, W.E., Lightfoot, E.N.: Transport Phenomena. Wiley, New York (1960)
Cho, S.-H., Park, J.-H., Beum, H.-T., Han, S.-S., Kim, J.-N.: A 2-stage psa process for the recovery of co2 from flue gas and its power consumption. In: Sang-Eon Park, J.-S.C., Kyu-Wan, L. (eds.) Studies in Surface Science and Catalysis, pp. 405–410. Elsevier, Amsterdam (2004)
Chue, K.T., Kim, J.N., Yoo, Y.J., Cho, S.H., Yang, R.T.: Comparison of activated carbon and zeolite ×13 for CO2 recovery from flue gas by pressure swing adsorption. Ind. Eng. Chem. Res. 34, 591–598 (1995)
Haghpanah, R., Nilam, R., Rajendran, A., Farooq, S., Karimi, I.A.: Cycle synthesis and optimization of a VSA process for postcombustion CO2 capture. AIChE J. 59, 4735–4748 (2013)
Kikkinides, E.S., Yang, R.T., Cho, S.H.: Concentration and recovery of CO2 from flue gas by pressure swing adsorption. Ind. Eng. Chem. Res. 32, 2714–2720 (1993)
Krishnamurthy, S., Rao, V.R., Guntuka, S., Sharratt, P., Haghpanah, R., Rajendran, A., Amanullah, M., Karimi, I.A., Farooq, S.: CO2 capture from dry flue gas by vacuum swing adsorption: a pilot plant study. AIChE J. 60, 1830–1842 (2014)
Maring, B.J., Webley, P.A.: A new simplified pressure/vacuum swing adsorption model for rapid adsorbent screening for CO2 capture applications. Int. J. Greenh. Gas Control 15, 16–31 (2013)
Na, B.K., Lee, H., Koo, K.K., Song, H.K.: Effect of rinse and recycle methods on the pressure swing adsorption process to recover CO2 from power plant flue gas using activated carbon. Ind. Eng. Chem. Res. 41, 5498–5503 (2002)
Reynolds, S.P., Mehrotra, A., Ebner, A.D., Ritter, J.A.: Heavy reflux PSA cycles for CO2 recovery from flue gas: Part I. Performance evaluation. Adsorption 14, 399–413 (2008)
Ruthven, D.M., Farooq, S., Knaebel, K.S.: Pressure Swing Adsorption. VCH Publishers Inc., New York (1994)
Shen, C.Z., Liu, Z., Li, P., Yu, J.G.: Two-stage VPSA process for CO2 Capture from flue gas using activated carbon beads. Ind. Eng. Chem. Res. 51, 5011–5021 (2012)
Sircar, S., Golden, T.C.: Purification of hydrogen by pressure swing adsorption. Sep. Sci. Technol. 35, 667–687 (2000)
Sircar, S., Kratz, W.C.: Simultaneous production of hydrogen and carbon dioxide from steam reformer off-gas by pressure swing adsorption. Sep. Sci. Technol. 23, 2397–2415 (1988)
Takamura, Y., Narita, S., Aoki, J., Hironaka, S., Uchida, S.: Evaluation of dual-bed pressure swing adsorption for CO2 recovery from boiler exhaust gas. Sep. Purif. Technol. 24, 519–528 (2001)
Waldron, W.E., Sircar, S.: Parametric study of a pressure swing adsorption process. Adsorption 6, 179–188 (2000)
Wang, L., Yang, Y., Shen, W., Kong, X., Li, P., Yu, J., Rodrigues, A.E.: Experimental evaluation of adsorption technology for CO2 capture from flue gas in an existing coal-fired power plant. Chem. Eng. Sci. 101, 615–619 (2013)
Warmuzinski, K.: Effect of pressure equalization on power requirements in PSA systems. Chem. Eng. Sci. 57, 1475–1478 (2002)
Xiao, P., Zhang, J., Webley, P., Li, G., Singh, R., Todd, R.: Capture of CO2 from flue gas streams with zeolite ×13 by vacuum-pressure swing adsorption. Adsorption 14, 575–582 (2008)
Xu, J., Weist, E.L.: Six bed pressure swing adsorption process with four steps of pressure equalization. US6454838B1 (2002)
Zhang, J., Webley, P.A.: Cycle development and design for CO2 capture from flue gas by vacuum swing adsorption. Environ. Sci. Technol. 42, 563–569 (2008)
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The authors gratefully acknowledge the funding provided by the Australian Government through its CRC Program to support this CO2CRC research project.
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Ntiamoah, A., Ling, J., Xiao, P. et al. CO2 capture by vacuum swing adsorption: role of multiple pressure equalization steps. Adsorption 21, 509–522 (2015). https://doi.org/10.1007/s10450-015-9690-8
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DOI: https://doi.org/10.1007/s10450-015-9690-8