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  • 51. Umeki, Kentaro
    et al.
    Namioka, Tomoaki
    Yoshikawa, Kunio
    Analysis of an updraft biomass gasifier with high temperature steam using a numerical model2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 90, no 1, p. 38-45Article in journal (Refereed)
    Abstract [en]

    High temperature steam gasification (HTSG) is a gasification technology which utilizes super-heated steam at a temperature above 1273 K. This paper addresses the performance analysis of an updraft HTSG gasifier using a numerical model. The experimental data obtained from a demonstration-scale gasifier was successfully simulated by the developed model. The calculation results showed 150–300 K temperature difference between gas phase and solid phase throughout the bed. Among a number of reactions, char gasification and water–gas shift reaction at char gasification zone played a major role to determine the syn-gas composition. Steam temperature, the ratio of steam to biomass and biomass feed rate affected the syn-gas composition while biomass particle diameter showed no significant effect. For the steam temperature and the ratio of steam to biomass, the difference of solid temperature at the bottom of gasifier determined the syn-gas composition. For biomass feed rate, the ratio of unreacted char extracted from the bottom of gasifier to supplied biomass determined the syn-gas composition.

  • 52.
    Umeki, Kentaro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Yamamoto, Kouichi
    Namioka, Tomoaki
    Yoshikawa, Kunio
    High temperature steam-only gasification of woody biomass2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 3, p. 791-798Article in journal (Refereed)
    Abstract [en]

    We have studied a high temperature steam gasification process to generate hydrogen-rich fuel gas from woody biomass. In this study, the performance of the gasification system which employs only high temperature steam exceeding 1200 K as the gasifying agent was evaluated in a 1.2 ton/day-scale demonstration plant. A numerical analysis was also carried out to analyze the experimental results. Both the steam temperature and the molar ratio of steam to carbon (S/C ratio) affected the reaction temperature which strongly affects the gasified gas composition. The H2 fraction in the produced gas was 35–55 vol.% at the outlet of the gasifier. Under the experimental conditions, S/C ratio had a significant effect on the gas composition through the dominant reaction, water–gas shift reaction. The tar concentration in the produced gas from the high temperature steam gasification process was higher than that from the oxygen-blown gasification processes. The highest cold gas efficiency was 60.4%. However, the gross cold gas efficiency was 35%, which considers the heat supplied by high temperature steam. The ideal cold gas efficiency of the whole system with heat recovery processes was 71%.

  • 53.
    Wagner, Katharina
    et al.
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.Thermochemical Energy Conversion Laboratory, Umeå University,Umeå, Sweden.
    Priscak, Juraj
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Kuba, Matthias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hofbauer, Hermann
    Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 248, p. 545-554Article in journal (Refereed)
    Abstract [en]

    The use of phosphorus-rich fuels in fluidized bed combustion is one probable way to support both heat and power production and phosphorus recovery. Ash is accumulated in the bed during combustion and interacts with the bed material to form layers and/or agglomerates, possibly removing phosphorus from the bed ash fraction. To further deepen the knowledge about the difference in the mechanisms behind the ash chemistry of phosphorus-lean and phosphorus-rich fuels, experiments in a 5 kW bench-scale-fluidized bed test-rig with K-feldspar as the bed material were conducted with bark, wheat straw, chicken manure, and chicken manure admixtures to bark and straw. Bed material samples were collected and studied for layer formation and agglomeration phenomena by scanning electron microscopy combined with energy dispersive X-ray spectrometry. The admixture of phosphorus-rich chicken manure to bark changed the layer formation mechanism, shifting the chemistry to the formation of phosphates rather than silicates. The admixture of chicken manure to straw reduced the ash melting and agglomeration risk, making it possible to increase the time until defluidization of the fluidized bed occurred. The results also highlight that an increased ash content does not necessarily lead to more ash melting related problems if the ash melting temperature is high enough.

  • 54.
    Westerlund, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Dahl, Jan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Absorbers in the open absorption system1994In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 48, no 1, p. 33-49Article in journal (Refereed)
    Abstract [en]

    This paper describes an experimental study of four different absorber designs in this type of system: cross-current and counter-current packed-absorbers, the spray absorber and fluid-bed absorber. In a laboratory pilot, plant, working lines for the absorbers were determined under adiabatic conditions. The influences of internal solution flow, gas flow, pressure drop and dissipation are discussed. The working lines represent the efficiency for each absorber. The highest performance occurs with the packed-bed absorbers, followed by the fluid-bed absorber and finally the spray absorber. For open absorption systems in air-conditioning applications (small scale) the fluid-bed absorber should be chosen

  • 55.
    Westerlund, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Dahl, Jan
    Open absorption system: experimental study in a laboratory pilot plant1991In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 38, no 3, p. 215-229Article in journal (Refereed)
    Abstract [en]

    The open absorption system is specially fitted in drying processes using air for the transport of the water. Advantages of the system are that different types of energy supply can be used, and that direct contact between the working media and the solution gives an effective absorber. This experimental study concerns measurements of the capacity of the system when a cross-flow absorber is used. Experiments were done under adiabatic and non-adiabatic conditions, and the results show that non-adiabatic conditions give a considerable increase in the absorption capacity. The dissipation of solution media increases strongly for air velocities over 2m/s. However, a demister can be used to reduce these losses. Investigation of the packing depth shows that the absorption takes place mainly in the first quarter of the packing. Different types of plastic packings were studied, the Telpac packing giving the best results.

  • 56.
    Westerlund, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Dahl, Jan
    Use of an open absorption heat-pump for energy conservation in a public swimming-pool1994In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 49, no 3, p. 275-300Article in journal (Refereed)
    Abstract [en]

    A conventional climatization system at a public swimming-pool normally uses outdoor air to remove the moisture from the facility. This practice results in large heat losses. An open absorption heat-pump can dehumidify the outlet air from the building: this makes it possible to recirculate a larger amount of air and so reduce the heating requirement for the facility significantly. Measurements on two types of systems have been performed during approximately 4000 h in a bath house in northern Sweden. In 1990, the use of an open absorption heat-pump decreased the heat supply by 445 MWh (from 742 MWh), while the electricity supply was increased by 233 MWh. The uncertainty in the annual energy saving with the open system can be estimated to be in the range 10-15%. If the present electric energy supply to the generator is replaced by another energy source, for example natural gas, the electricity demand of the absorption system will decrease considerably. The results show that public baths are an interesting application area for the open absorption technique

  • 57.
    Westerlund, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hermansson, Roger
    Fagerström, Jonathan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Flue gas purification and heat recovery: a biomass fired boiler supplied with an open absorption system2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 96, p. 444-450Article in journal (Refereed)
    Abstract [en]

    A new technique for energy recovery combined with particle separation from flue gas has been tested in this project. A conventional small boiler for biofuel produces besides heat also particles to the environment through the flue gas. Decreasing the impact on the environment is desirable. Increased efficiency can be obtained if the temperature and water content of the flue gas can be further reduced. Installing an open absorption system in the heat production unit fulfils both these demands. An experimental unit has been built and tested in the last 2 years. The results show a reduction of particles in the flue gas by 33–44% compared to the ordinary system. At the same time the heat production from the unit increased by 40% when fired with wet biofuels.

  • 58. Wetterlund, Elisabeth
    et al.
    Söderström, Mats
    Division of Energy Systems, Department of Mechanical Engineering, Linköping Institute of Technology.
    Biomass gasification in district heating systems - the effect of economic energy policies2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 9, p. 2914-2922Article in journal (Refereed)
    Abstract [en]

    Biomass gasification is considered a key technology in reaching targets for renewable energy and CO2 emissions reduction. This study evaluates policy instruments affecting the profitability of biomass gasification applications integrated in a Swedish district heating (DH) system for the medium-term future (around year 2025). Two polygeneration applications based on gasification technology are considered in this paper: (1) a biorefinery plant co-producing synthetic natural gas (SNG) and district heat; (2) a combined heat and power (CHP) plant using integrated gasification combined cycle technology. Using an optimisation model we identify the levels of policy support, here assumed to be in the form of tradable certificates, required to make biofuel production competitive to biomass based electricity generation under various energy market conditions. Similarly, the tradable green electricity certificate levels necessary to make gasification based electricity generation competitive to conventional steam cycle technology, are identified. The results show that in order for investment in the SNG biorefinery to be competitive to investment in electricity production in the DH system, biofuel certificates in the range of 24–42 EUR/MWh are needed. Electricity certificates are not a prerequisite for investment in gasification based CHP to be competitive to investment in conventional steam cycle CHP, given sufficiently high electricity prices. While the required biofuel policy support is relatively insensitive to variations in capital cost, the required electricity certificates show high sensitivity to variations in investment costs. It is concluded that the large capital commitment and strong dependency on policy instruments makes it necessary that DH suppliers believe in the long-sightedness of future support policies, in order for investments in large-scale biomass gasification in DH systems to be realised.

  • 59.
    Xie, Yujiao
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Björkmalm, Johanna
    SP Technical Research Institute of Sweden, Box 857, 501 15 Borås.
    Ma, Chunyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Willquist, Karin
    SP Technical Research Institute of Sweden, Box 857, 501 15 Borås.
    Yngvesson, Johan
    SP Technical Research Institute of Sweden, Box 857, 501 15 Borås.
    Wallberg, Ola
    Department of Chemical Engineering, Lund University.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Techno-economic evaluation of biogas upgrading using ionic liquids in comparison with industrially used technology in Scandinavian anaerobic digestion plants2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 742-750Article in journal (Refereed)
    Abstract [en]

    The process of biogas upgrading with ionic liquids, i.e. pure 1-butyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)imide ([bmim][Tf2N]), aqueous choline chloride/urea (ChCl/Urea), and aqueous 1-allyl-3-methyl imidazole formate ([Amim][HCOO]), was simulated in Aspen Plus and compared with the conventional water scrubbing upgrading technique. The comparisons of the performances on the amount of recirculated solvents and energy usage show the following order: aqueous [Amim][HCOO]<aqueous ChCl/Urea<[bmim][Tf2N]<water. Six different co-digestion plants (anaerobic digestion, AD, plants) were surveyed to acquire data for comparison. The selected plants had different raw biogas production capacities and produced gas with differing methane content. The data confirmed the simulation results that the type of substrate and the configuration of AD process are two factors affecting energy usage, investment cost, as well as operation and maintenance costs for the subsequent biogas upgrading. In addition, the simulation indicated that the energy usage of the ionic liquid-based upgrading was lower than that of the conventional upgrading techniques in Scandinavian AD plants. The estimated cost including investment, operation and maintenance for the ionic liquid technology showed to be lower than that for the water scrubbing upgrading process.

  • 60.
    Xie, Yujiao
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ma, Chunyan
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Lu, Xiaohua
    Key Laboratory of Material and Chemical Engineering, Nanjing University of Technology.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Evaluation of imidazolium-based ionic liquids for biogas upgrading2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 175, p. 69-81Article in journal (Refereed)
    Abstract [en]

    The conceptual processes for biogas upgrading using three imidazolium-based ionic liquids ([hmim][Tf2N], [bmim][Tf2N] and [bmim][PF6]) were simulated in Aspen Plus to study the effect of properties of ionic liquids (ILs) on the process performance. To conduct the process simulation, each IL was input into Aspen Plus as a pseudo component, their critical properties were estimated by group contribution method, and their thermo-physical properties were correlated from the available experimental data by semi-empirical equations. The gas solubility in ILs was modeled with the non-random two-liquid model and Redlich–Kwong equation of state. Among the studied ILs, the simulation results show that the amount of recirculated solvents and the total energy consumption for upgrading process using ILs follow: [bmim][Tf2N] < [bmim][PF6] < [hmim][Tf2N]. The effects of density and viscosity of ILs on pressure drop and diameter of the absorber as well as the effects of operational pressures and temperatures on the process efficiency were investigated. It is found that the energy consumption increases with increasing pressure and temperature in the absorber and decreases with increasing pressure in the first flash tank. The ILs-based technology was further compared with water scrubbing and aqueous choline chloride/urea scrubbing, and the comparison shows that the total energy consumptions follow: 50%ChCl/Urea-water < [bmim][Tf2N] scrubbing < water scrubbing

  • 61.
    Xie, Yujiao
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Zhang, Yingying
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Energy consumption analysis for CO2 separation using imidazolium-based ionic liquids2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 136, p. 325-335Article in journal (Refereed)
    Abstract [en]

    CO2 solubility in ionic liquids has been measured extensively in order to develop ionic liquid-based technology for CO2 separation. However, the energy consumption analysis has not been investigated well for such technology. In order to carry out the energy consumption analysis for CO2 separation using ionic liquids based on available experimental data, in this work, the experimental data of the CO2 solubility in imidazolium-based ionic liquids at pressures below 10 MPa was surveyed and evaluated by a semi-empirical thermodynamic model firstly. Based on the reliable experimental solubility data, the enthalpy of CO2 absorption was further calculated by the thermodynamic model. The results show that the CO2 absorption enthalpy in the studied ionic liquids is dominated by the enthalpy of CO2 dissolution and the contribution of excess enthalpy increases with increasing CO2 solubility in ionic liquids. The magnitude of the CO2 absorption enthalpy decreases with increasing chain length in cation and strongly depends on the anion of ionic liquids. Furthermore, the energy consumption for a CO2 separation process by pressure swing and/or temperature swing was investigated. For the pressure swing process, the Henry’s constant of CO2 in ionic liquids is an important factor for energy consumption analysis; If CO2 is absorbed at 298 K and 1 MPa and ionic liquid is regenerated by decreasing the pressure to 0.1 MPa at the same temperature, among the studied ionic liquids, [emim][EtSO4] is the solvent with the lowest energy consumption of 9.840 kJ/mol CO2. For the temperature swing process, the heat capacity of ionic liquids plays a more important role; If CO2 is absorbed at 298 K and desorbed at 323 K and 0.1 MPa, [emim][PF6] is the solvent with the lowest energy demand of 888.9 kJ/mol CO2. If the solvent is regenerated by releasing pressure and increasing temperature, both the Henry’s constant of CO2 in ionic liquids and the heat capacity of ionic liquids are important for analyzing the energy consumption; If CO2 is absorbed at 298 K and 1 MPa and ionic liquid is regenerated at 323 K and 0.1 MPa, [bmim][Tf2N] is the solvent with the lowest energy consumption of 57.71 kJ/mol CO2.

  • 62.
    Zetterholm, Jonas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Sundelin, Bo
    SSAB EMEA Oxelösund , SSAB Special Steels Oxelösund.
    Martin, P.M.
    Siemens VAI Metals Technologies, United States.
    Wang, C.
    Department of Process Integration, Swerea MEFOS AB.
    Dynamic modelling for the hot blast stove2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, no 2, p. 2142-2150Article in journal (Refereed)
    Abstract [en]

    A large amount of energy is required in the production of steel where the preheating of blast in the hot blast stoves for iron-making is one of the most energy-intensive processes. To improve the energy efficiency of the steelmaking it is necessary to investigate how to improve the hot blast stove operation.In this work a mathematic model for evaluating the performance of the hot blast stove was developed using a finite difference approximation for the heat transfer inside the stove during operation. The developed model was calibrated and validated by using the process data from hot blast stove V26 at SSABs plant in Oxelösund, Sweden. The investigation shows a good agreement between the measured and modelled data.As a case study, the developed model was used to simulate the effect of a new concept of OxyFuel technique to hot blast stoves. The investigation shows that, by using this OxyFuel technique, it is possible to maintain the blast temperature while removing the usage of coke oven gas (COG). The saved COG can be used to replace some fossil fuel, such as oil and LPG.Furthermore, the effect of the cycle time on the single stove was studied. As expected, both the hot blast and flue gas temperatures are increased when increasing the cycle time. This shows that it is a good strategy for the hot blast stove to increase the blast temperature if the stove is currently not operated with the maximum allowed flue-gas temperature. 

  • 63.
    Zetterholm, Jonas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Pettersson, Karin
    RISE Research Institutes of Sweden, Eklandagatan 86, SE-412 61 Gothenburg.
    Leduc, Sylvain
    International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg.
    Resource efficiency or economy of scale: Biorefinery supply chain configurations for co-gasification of black liquor and pyrolysis liquids2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 230, p. 912-924Article in journal (Refereed)
    Abstract [en]

    Biorefineries for the production of fuels, chemicals, or materials can be an important contributor to reducing dependence on fossil fuels. The economic performance of the biorefinery supply chain can be increased by, for example, industrial integration to utilise excess heat and products, increasing size to improve economy of scale, and using intermediate upgrading to reduce feedstock transport cost. To enable a large-scale introduction of biorefineries it is important to identify cost efficient supply chain configurations.

    This work investigates a lignocellulosic biorefinery concept integrated with forest industry, focusing on how different economic conditions affect the preferred supply chain configurations. The technology investigated is black liquor gasification, with and without the addition of pyrolysis liquids to increase production capacity. Primarily, it analyses trade-offs between high biomass conversion efficiency and economy of scale effects, as well as the selection of centralised vs. decentralised supply chain configurations.

    The results show the economic advantage for biomass efficient configurations, when the biorefinery investment is benefited from an alternative investment credit due to the replacement of current capital-intensive equipment at the host industry. However, the investment credit received heavily influenced the cost of the biorefinery and clearly illustrates the benefit for industrial integration to reduce the cost of biorefineries. There is a benefit for a decentralised supply chain configuration under very high biomass competition. However, for lower biomass competition, site-specific conditions will impact the favourability of either centralised or decentralised supply chain configurations.

  • 64.
    Zhang, Yingying
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology.
    Energy consumption analysis for CO2 separation from gas mixtures2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 130, no S1, p. 237-243Article in journal (Refereed)
    Abstract [en]

    CO2 separation is an energy intensive process, which plays an important role in both energy saving and CO2 capture and storage (CCS) implementation to deal with global warming. To quantitatively investigate the energy consumption of CO2 separation from different CO2 streams and analyze the effect of temperature, pressure and composition on energy consumption, in this work, the theoretical energy consumption of CO2 separation from flue gas, lime kiln gas, biogas and bio-syngas was calculated. The results show that the energy consumption of CO2 separation from flue gas is the highest and that from biogas is the lowest, and the concentration of CO2 is the most important factor affecting the energy consumption when the CO2 concentration is lower than 0.15 in mole fraction. Furthermore, if the CO2 captured from flue gases in CCS was replaced with that from biogases, i.e. bio-CO2, the energy saving would be equivalent to 7.31 million ton standard coal for China and 28.13 million ton standard coal globally, which corresponds to 0.30 billion US$ that can be saved for China and 1.36 billion US$ saved globally. This observation reveals the importance of trading fossil fuel-based CO2 with bio-CO2.

  • 65.
    Zhang, Yingying
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Xie, Yujiao
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Screening of conventional ionic liquids for carbon dioxide capture and separation2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 162, p. 1160-1170Article in journal (Refereed)
    Abstract [en]

    CO2 capture and storage could efficiently mitigate CO2 emissions, wherein CO2 capture is a crucial energy-intensive process. Ionic liquids (ILs) have been proposed as potential liquid absorbents for CO2 separation. The CO2 absorption capacity and selectivity of ILs have also been investigated extensively. Although ILs have been screened for CO2 separation, only specific ILs have been examined in terms of energy consumption. In this study, 76 conventional ILs were collected and screened in terms of energy consumption to establish potential ILs for CO2 separation. Seventeen ILs were screened according to the CO2 dissolution enthalpy and CO2 working capacity criteria obtained from the Henry’s law constant in the preliminary screening. Seven ILs were then screened from the 17 ILs according to the CO2 working capacity from the measured CO2 solubility in the final screening. The energy consumptions of the seven screened ILs (i.e., [Emim][NTf2], [Bmim][BF4], [Bmim][PF6], [Bmim][NTf2], [Hmim][NTf2], [Bmpy][NTf2], and [Hmpy][NTf2]) were calculated, and the corresponding gas solubility selectivities were discussed. The energy consumptions and properties of the seven screened ILs were compared with those of the commercial CO2 absorbents of 30 wt% MEA, 30 wt% MDEA, and dimethyl ethers of polyethylene glycol (Selexol™ or Coastal AGR®). The results showed that the energy consumptions of the seven screened ILs were lower than those of the commercial CO2 absorbents. [Hmpy][NTf2] showed the lowest energy consumption among the seven screened ILs under the operating conditions set in this study.

  • 66.
    Zhang, Yingying
    et al.
    Department of Material and Chemical Engineering, Zhengzhou University of Light Industry.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Xie, Yujiao
    School of Chemical Engineering, Shandong University of Technology.
    Lu, Xiaohua
    Key Laboratory of Material and Chemical Engineering, Nanjing Tech University, Nanjing .
    Thermodynamic analysis of CO2 separation from biogas with conventional ionic liquids2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 217, p. 75-87Article in journal (Refereed)
    Abstract [en]

    CO2 separation plays an important role in energy saving and CO2 emission reduction to address global warming. Ionic liquids (ILs) have been proposed as potential absorbents for CO2 separation, and a large amount of ILs have been synthesized to achieve this purpose. To screen ILs for CO2 separation, CO2 absorption capacity/selectivity and energy use have been considered, whereas the required amount of IL has been seldom involved. In this work, CO2 separation from biogas with 30 conventional ILs was analyzed theoretically on the basis of the Gibbs free energy change combining the amount of IL needed and the energy use. The desorption temperature was estimated from the absorption pressure, and then the amount of IL needed and the energy use were calculated. Thermodynamic analysis shows that the absorption pressure and the desorption temperature need to be changed to achieve optimal separation. Several ILs were screened with certain criteria, namely, the amount of IL needed and energy use. The performance of the screened ILs was compared with that of commercial CO2 absorbents (30 wt% MEA, 30 wt% MDEA, DEPG, and water). The comparison with DEPG and water shows that the screened physical ILs are promising for IL-based technologies because of their advantages of negligible vaporization enthalpy, low amount of absorbent needed, or low energy use. A comparison with 30 wt% MEA and 30 wt% MDEA indicates that chemical IL has negligible vaporization enthalpy and low energy use. These findings show that the screened ILs are promising for CO2 separation from biogas.

  • 67.
    Ögren, Yngve
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. RISE-Energy Technology Center AB.
    Tóth, Pál
    RISE-Energy Technology Center AB.
    Garami, Attila
    University of Miskolc, Faculty of Material Sciences and Engineering, Institute of Energy and Quality Affairs, Department of Combustion Technology and Thermal Energy.
    Sepman, Alexey
    RISE-Energy Technology Center AB.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. RISE-Energy Technology Center AB.
    Development of a vision-based soft sensor for estimating equivalence ratio and major species concentration in entrained flow biomass gasification reactors2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 226, p. 450-460Article in journal (Refereed)
    Abstract [en]

    A combination of image processing techniques and regression models was evaluated for predicting equivalence ratio and major species concentration (H2, CO, CO2 and CH4) based on real-time image data from the luminous reaction zone in conditions and reactors relevant to biomass gasification. Two simple image pre-processing routines were tested: reduction to statistical moments and pixel binning (subsampling). Image features obtained by using these two pre-processing methods were then used as inputs for two regression algorithms: Gaussian Process Regression and Artificial Neural Networks. The methods were evaluated by using a laboratory-scale flat-flame burner and a pilot-scale entrained flow biomass gasifier. For the flat-flame burner, the root mean square error (RMSE) were on the order of the uncertainty of the experimental measurements. For the gasifier, the RMSE was approximately three times higher than the experimental uncertainty – however, the main source of the error was the quantization of the training dataset. The accuracy of the predictions was found to be sufficient for process monitoring purposes. As a feature extraction step, reduction to statistical moments proved to be superior compared to pixel binning.

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