Cycle Development and Design for CO 2 Capture from Flue Gas by Vacuum Swing Adsorption

Cooperative Research Centre for Greenhouse Gas Technologies, Department of Chemical Engineering, Monash University, Victoria 3800, Australia.
Environmental Science and Technology (Impact Factor: 5.33). 02/2008; 42(2):563-9. DOI: 10.1021/es0706854
Source: PubMed


CO2 capture and storage is an important component in the development of clean power generation processes. One CO2 capture technology is gas-phase adsorption, specifically pressure (or vacuum) swing adsorption. The complexity of these processes makes evaluation and assessment of new adsorbents difficult and time-consuming. In this study, we have developed a simple model specifically targeted at CO2 capture by pressure swing adsorption and validated our model by comparison with data from a fully instrumented pilot-scale pressure swing adsorption process. The model captures nonisothermal effects as well as nonlinear adsorption and nitrogen coadsorption. Using the model and our apparatus, we have designed and studied a large number of cycles for CO2 capture. We demonstrate that by careful management of adsorption fronts and assembly of cycles based on understanding of the roles of individual steps, we are able to quickly assess the effect of adsorbents and process parameters on capture performance and identify optimal operating regimes and cycles. We recommend this approach in contrast to exhaustive parametric studies which tend to depend on specifics of the chosen cycle and adsorbent. We show that appropriate combinations of process steps can yield excellent process performance and demonstrate how the pressure drop, and heat loss, etc. affect process performance through their effect on adsorption fronts and profiles. Finally, cyclic temperature profiles along the adsorption column can be readily used to infer concentration profiles-this has proved to be a very useful tool in cyclic function definition. Our research reveals excellent promise for the application of pressure/vacuum swing adsorption technology in the arena of CO2 capture from flue gases.

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    • "The use of CAs to remove CO 2 from flue gas requires the enzyme to be integrated into the scrubbing process (Cowan et al., 2003). The flue gas first undergoes a pre-scrubbing treatment, which requires the use of solvents to remove anions and various other impurities (Maeda et al., 1995; Zhang and Webley, 2008). The flue gas then enters a room temperature (RT) chamber containing immobilized TcruCA, or another suitable CA, along with a CO 2 scrubbing solvent. "
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    ABSTRACT: The α-class carbonic anhydrase (CA) from the thermophilic gammaproteobacterium Thiomicrospira crunogena XCL-2 (TcruCA) has been recently proposed as a candidate enzyme for carbon dioxide removal (CDR) in flue gas scrubbing systems. However during this process, the enzyme may be exposed to anionic impurities which can limit the use of CA for CDR. The inhibition of TcruCA by various anions, some of which are found in flue gas, is reported. The majority of the anions tested display weak (mM) inhibition but some, such as the metal poisons and anionic acids, exhibit stronger (μM) inhibition. Most relevant to the use of CA in CDR is the inhibition by SOx, NOx, and Hg2+, which can be removed through a pre-scrubbing treatment. In addition, the active site structural architecture of TcruCA is compared with other α-class CAs and differences in catalytic efficiency and anion inhibition are discussed. This study provides information regarding anionic inhibition of CAs as bio-catalytic CDR agents and the results should therefore be considered in the design of CA-mediated flue gas scrubbing systems.
    Full-text · Article · Aug 2015 · Chemical Engineering Science
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    • "Indeed, the Si/Al ratio and the number/nature of extraframework cations can play a major role in controlling the CO 2 adsorptive properties [22] [23]. "
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    ABSTRACT: Among all the post-combustion technologies, adsorption processes on solid sorbents are attractive due to their low energy requirements. Great interest is focused on ultra-fine materials, whose chemicophysical properties can be tuned at the molecular level. However, the capture capacity of these fine materials strongly depends on the technology adopted for the adsorption tests. Common techniques, such as thermogravimetric analysis or fixed bed operation, end up underestimating it, since these fine powders are organized in structures (aggregates), which can be difficultly permeable to the gaseous phase. Therefore, the choice of the proper adsorption technique becomes crucial. In this framework sound-assisted fluidization has already been proved to maximize the CO2 adsorption capacity of fine sorbents with respect to common technologies, due to the higher exploitation of the exposed surface. The aim of the present work is, therefore, to compare the adsorption performances of different materials (two activated carbons, two zeolites and a metal organic framework) under sound-assisted fluidization conditions (140 dB–80 Hz) in order to maximize the gas–solid contact efficiency and, in turn, minimize the limitations to the intrinsic adsorption capacity of the sorbents. All the tests were performed at ambient temperature and pressure with values of CO2 concentration typical of flue gases (5–10 vol.%). The different behaviors exhibited by the materials were explained on the basis of their textural properties. In particular, the microporosity falling in the range of 8.3–12 Å strongly affects the CO2 adsorption performances under the investigated operating conditions.
    Full-text · Conference Paper · Jun 2015
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    • "Thus, the development of a promising material that would adsorb CO 2 with a high capacity and the ability to be regenerated with a low energy input will certainly enhance the competitiveness of an adsorptive separation system in a flue gas treatment [7]. The cyclic adsorption–desorption operation was commonly carried out by means of pressure swing adsorption (PSA), temperature swing adsorption (TSA), or vacuum swing adsorption (VSA) with many kinds of solid materials including carbon based adsorbents [8] [9] [10] [11] [12] [13] [14] [15] and zeolite based adsorbents [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27]. In order to make CO 2 desorption from the spent adsorbents become more practical in the field, a combination of TSA and VSA (TVSA) was employed to reduce desorption time of CO 2 from the spent amine-loaded carbon nanotubes (CNTs) [12] [28] and spherical mesoporous silica particles (MSPs) [29] as compared to TSA or VSA. "
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    ABSTRACT: Abstract A dual-column temperature/vacuum swing adsorption (TVSA) with 3-aminopropyltriethoxysilane-loaded carbon nanotubes (CNT(APTS)) was built to study cyclic CO2 capture from gas streams. The working CO2 capacities and the characteristics of CNT(APTS) were preserved through 100 TVSA cycles under dry or wet conditions, displaying the multi-cycle stability of CO2 capture with CNT(APTS). The cyclic working CO2 capacity of CNT(APTS) was notably enhanced in the presence of saturated water vapor in the gas stream at 25 °C which gives relatively high desorbed CO2 concentrations (∼67%). These results suggest that a dual-column TVSA with solid CNT(APTS) has the possibility to be a promising CO2 capture technology, especially in the post-flue gas desulfurization in which saturated water vapor is present in the flue gas.
    Full-text · Article · Jan 2014 · Applied Energy
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