| 1. |
- Nookuea, Worrada, 1985-, et al.
(författare)
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Regenerating CO2 at High Pressures for Chemical Absorption
- 2018
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Konferensbidrag (refereegranskat)abstract
- Chemical absorption is suitable to capture CO2 from the large point sources with low CO2 concentration such as from the power plant. However, high-energy requirement for solvent regeneration is the main burden to apply this capture technology. Operating the desorber at high pressures has the potential to reduce the energy penalty of CO2 capture and storage since it can reduce the compression work after the desorption. In this work, a rate-based chemical absorption model was developed in Aspen Plus to investigate the impact of operating pressure. After absorption, the solvent pump lifts the pressure of the rich solvent, and CO2 is regenerated at a lifted pressure in the desorber. After condensation and dehydration, the high pressure CO2 is compressed to 110 bar by the two-stage compressor with inter-cooling to 313.15 K for transportation. The results from steady state simulations show that by increasing the desorber pressure, both the required thermal energy of solvent regeneration and the power consumption of compressors decrease, even though the power consumption of pumps and the temperature of solvent regeneration increase. However, from the exergy analyses, the total exergy increases slightly with the desorber pressure.
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| 2. |
- An, Lin, et al.
(författare)
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CO2 capture using a superhydrophobic ceramic membrane contactor
- 2015
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Ingår i: CLEAN, EFFICIENT AND AFFORDABLE ENERGY FOR A SUSTAINABLE FUTURE. - : Elsevier. ; 75, s. 2287-2292
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Konferensbidrag (refereegranskat)abstract
- Wetting and fouling of membrane contactor result in performance deterioration of membrane gas absorption system for CO2 post-combustion capture of coal-fired power plants. To solve these problems, in this study, a superhydrophobic ceramic (SC) membrane contactor was fabricated by chemically modification using 1H, 1H, 2H, 2H-perfluorooctylethoxysilane (FAS) solution. The membrane contactor fabrication costs for both SC membrane and PP (polypropylene) membrane contactors per unit mass absorbed CO2 were roughly the same. However, by using the SC membrane, the detrimental effects of wetting can be alleviated by periodic drying to ensure a high CO2 removal efficiency (>90%), whereas the drying does not work for the PP membrane. The SC membrane contactor exhibited a better anti-fouling ability than the PP membrane contactor because the superhydrophobic surface featured a self-cleaning function. To ensure continuous CO2 removal with high efficiency, a method that two SC membrane contactors alternatively operate combined with periodic drying was proposed. (C) 2015 Published by Elsevier Ltd.
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| 3. |
- Li, Hongliang, et al.
(författare)
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Catalytic performance and characterization of Al2O3-supported Pt-Co catalyst coatings for preferential CO oxidation in a micro-reactor
- 2010
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 387:1-2, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- Platinum-cobalt (Pt-Co) catalyst coatings are studied for preferential oxidation of carbon monoxide (PROX) ill hydrogen-rich gas streams. Experimental results show a role for cobalt in improving catalytic activity. The most active catalyst coating can decrease carbon monoxide concentrations from 1% to a value of less than 10 ppm for GHSV values ranging from 40,000 to 120,000 ml g(-1) h(-1). This catalyst coating can work at a wide window of operation ill terms of temperature. Transmission electron microscopy, selected-area electron diffraction, and diffuse reflectance infrared Fourier transform spectroscopy show that the addition of Co forms Pt3Co intermetallic compounds and slightly increases the average particle size. In situ laser Raman spectroscopy reveals the co-existence of Co metal and its oxides on the catalyst surface, due to gradual oxidation of Co by gas phase oxygen within the initial stage of the PROX reaction. The promotional effect of Co during PROX is confirmed and ascribed to this Pt3Co intermetallic compound and the synergetic effect of Co-0 and Co chi+. The high accessibility of the reactant to Pt3Co species appears favorable and crucial for PROX.
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| 4. |
- Li, Hailong, et al.
(författare)
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Feasibility study on combining anaerobic digestion and biomass gasification to increase the production of biomethane
- 2015
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 100, s. 212-219
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Tidskriftsartikel (refereegranskat)abstract
- There is a rapid growing interest in using biomethane as fuel for transport applications. A new concept is proposed to combine anaerobic digestion and biomass gasification to produce biomethane. H-2 is separated from the syngas generated by biomass gasification in a membrane system, and then is used to upgrade raw biogas from anaerobic digestion. Simulations have been conducted based on the real operation data of one full scale biogas plant and one full scale biomass gasification plant in order to investigate the feasibility of the new concept. Results show that although less power and heat are generated compared to the gasification plant, which results in a lower overall efficiency, much more biomethane can be produced than the biogas plant; and the new concept can achieve a higher exergy efficiency. Due to the increasing price of biomethane, the novel concept demonstrates a big potential of income increase. For example, at a biomethane price of 12.74SEK/kg, the annual income can be increased by 53% compared to the total income of the biogas and gasification plant. (C) 2015 Elsevier Ltd. All rights reserved.
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| 5. |
- Lu, Yuexia, et al.
(författare)
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CO2 capture by the absorption process in membrane contactors
- 2009
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Ingår i: The First International Conference on Applied Energy (ICAE09).
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Konferensbidrag (refereegranskat)abstract
- Membrane has a potential to improve the CO2 capture process. In this paper, experimentswere carried out to investigate the impact of amine absorbents on membrane surfaceproperties with polypropylene (PP) fibers immersed in monoethanolamine (MEA) andmethyldiethanolamine (MDEA) aqueous solutions with and without CO2 loading. The surfacemorphological changes of the membrane were examined by using scanning electronmicroscopy (SEM). The experimental results showed that the fibers immersed in the aqueoussolutions without CO2 loading underwent significant deformation than those with CO2 loading,which is mostly linked to the decrease of absorbent concentration with the reaction betweenCO2 and aqueous solutions. It was also found that the morphological changes of membraneimmersed in MDEA were severer than that in MEA due to the lower surface tension of theformer.
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| 6. |
- Lu, Yuexia, et al.
(författare)
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INFLUENCE OF MEA AND MDEA SOLUTIONS ON SURFACE MORPHOLOGY OF MICROPOROUS POLYPROPYLENE MEMBRANES
- 2009
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Ingår i: The First International Conference on Applied Energy (ICAE09).
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Konferensbidrag (refereegranskat)abstract
- Membrane has a potential to improve the CO2 capture process. In this paper, experimentswere carried out to investigate the impact of amine absorbents on membrane surfaceproperties with polypropylene (PP) fibers immersed in monoethanolamine (MEA) andmethyldiethanolamine (MDEA) aqueous solutions with and without CO2 loading. The surfacemorphological changes of the membrane were examined by using scanning electronmicroscopy (SEM). The experimental results showed that the fibers immersed in the aqueoussolutions without CO2 loading underwent significant deformation than those with CO2 loading,which is mostly linked to the decrease of absorbent concentration with the reaction betweenCO2 and aqueous solutions. It was also found that the morphological changes of membraneimmersed in MDEA were severer than that in MEA due to the lower surface tension of theformer.
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| 7. |
- Lv, Yuexia, et al.
(författare)
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Experimental studies on simultaneous removal of CO2 and SO2 in a polypropylene hollow fiber membrane contactor
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 97, s. 283-288
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Tidskriftsartikel (refereegranskat)abstract
- Membrane gas absorption technology is a promising alternative to conventional technologies for the mitigation of acid gases. In this study, simultaneous removal of SO2 and CO2 from coal-fired flue gas was carried out in a polypropylene hollow fiber membrane contactor using aqueous monoethanolamine as the absorbent. The influences of liquid and gas flow rates on the simultaneous absorption performance of CO2 and SO2 were investigated. The experimental results indicated that the membrane contactor could eliminate these two sour gases simultaneously and effectively. Absorption of SO2 and CO2 was enhanced by the increase in liquid flow rate and decrease in gas flow rate. It was observed that a small amount of SO2 in the flue gas had a slight influence on the absorption of CO2. In addition, the membrane contactor was operated continuously for two weeks to evaluate its duration performance. The results showed that the CO2 mass transfer rate was decreased significantly with the operating time due to partial wetting of membrane pores. After 14 days of continuous operation, the CO2 mass transfer rate of the wetted membrane contactor was decreased by 41% but could be retrieved to 86% of the fresh one by increasing the gas phase pressure.
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| 8. |
- Lv, Yuexia, et al.
(författare)
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Fabrication and characterization of superhydrophobic polypropylene hollow fiber membranes for carbon dioxide absorption
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 90:1, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- The membrane wetting by amine absorbents results in performance deterioration of membrane gas absorption system for CO(2) post-combustion capture. To solve this problem, in this study, the polypropylene membrane fiber was modified by depositing a rough layer on the surface to improve its hydrophobicity. Weighing the coating homogeneity, hydrophobicity and modification process efficiency, the mixture of cyclohexanone and MEK system was considered as the best non-solvent. The contact angle increased dramatically from 122 to 158 by the modification, thereby obtaining superhydrophobic membrane surface. The membrane-absorbent interaction results demonstrated that the modification treatment effectively enhanced the stability and maintained the superhydrophobicity of fibers contacting with the absorbent. In addition, continuous CO(2) absorption experiments for up to 20 days were carried out in untreated and modified polypropylene hollow fiber membrane contactors, using 1 mol L(-1) MEA solution as the absorbent. The long-term system operation results indicated that, even though additional mass transfer resistance was introduced by the surface coating, the modified polypropylene hollow fiber membrane contactor was still technically feasible for CO(2) capture from the power stations.
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| 9. |
- Lv, Yuexia, et al.
(författare)
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Wetting of polypropylene hollow fiber membrane contactors
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 362:1-2, s. 444-452
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Tidskriftsartikel (refereegranskat)abstract
- Membrane wetting by absorbents leads to an Increase in mass transfer resistance and a deterioration in CO2 absorption performance during the membrane gas absorption process In order to better understand the wetting mechanism of membrane pores during their prolonged contact with adsorbents, polypropylene (PP) hollow fibers were Immersed in three different absorbents for up to 90 days Monoethanolamine, methyldiethanolamine, and deionized water were applied as absorbent solutions The characterization results of membrane samples confirm that the absorbent molecules diffuse into PP polymers during the exposure process, resulting in the swelling of the membranes The absorption-swelling wetting mechanism is proposed to explain observations made during the wetting process The strong reduction of contact angles indicates that the membrane surface hydrophobicity decreases remarkably during immersion due to membrane-absorbent interaction Membrane surface morphologies and surface roughness suffer from significant and complicated changes after immersing the membrane fibers in the absorbents. Immersion in an absorbent with a high surface tension results in small changes in membrane surface morphology. As indicated by the experimental results, improving membrane surface hydrophobicity may be an effective way of overcoming wetting problems.
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| 10. |
- Wen, Zhenzhong, et al.
(författare)
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Biodiesel production from waste cooking oil catalyzed by TiO2-MgO mixed oxides
- 2010
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 101:24, s. 9570-9576
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Tidskriftsartikel (refereegranskat)abstract
- Mixed oxides of TiO2-MgO obtained by the sal-gel method were used to convert waste cooking oil into biodiesel. Titanium improved the stability of the catalyst because of the defects induced by the substitution of Ti ions for Mg ions in the magnesia lattice. The best catalyst was determined to be MT-1-923, which is comprised of an Mg/Ti molar ratio of 1 and calcined at 923 K, based on an assessment of the activity and stability of the catalyst. The main reaction parameters, including methanol/oil molar ratio, catalyst amount, and temperature, were investigated. The catalytic activity of MT-1-923 decreased slowly in the reuse process. After regeneration, the activity of MT-1-923 slightly increased compared with that of the fresh catalyst due to an increase in the specific surface area and average pore diameter. The mixed oxides catalyst. TiO2-MgO, showed good potential in large-scale biodiesel production from waste cooking oil.
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