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Montecchio, F., Altimira, M., Andersson, A. & Engvall, K. (2019). Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications. Chemical Engineering Journal, 369, 280-291
Open this publication in new window or tab >>Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications
2019 (English)In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 369, p. 280-291Article in journal (Refereed) Published
Abstract [en]

The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the developed CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
CFD simulation, Reactor modelling, Reactor scale-up, Air treatment, UV reactor, VOC abatement
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-251191 (URN)10.1016/j.cej.2019.03.094 (DOI)000463344800029 ()2-s2.0-85062730612 (Scopus ID)
Note

QC 20190523

Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2019-05-29Bibliographically approved
Mesfun, S., Lundgren, J., Toffolo, A., Lindbergh, G., Lagergren, C. & Engvall, K. (2019). Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant. Journal of energy resources technology, 141(1), Article ID 012002.
Open this publication in new window or tab >>Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant
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2019 (English)In: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 141, no 1, article id 012002Article in journal (Refereed) Published
Abstract [en]

Producer gas from biomass gasification contains impurities like tars, particles, alkali salts, and sulfur/nitrogen compounds. As a result, a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into synthetic natural gas (SNG). A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of syngas produced. Internal rate of return (IRR) is evaluated as an economic indicator of the processes considered. Results indicate that, depending on process configuration, the production of SNG can be boosted by approximately 50-60% without the need of an additional carbon source, i.e., for the same biomass input as in standalone operation of the GoBi-Gas plant.

Place, publisher, year, edition, pages
ASME Press, 2019
Keywords
Electrolysis, Molten-carbonate, Process integration, Renewable electricity, SNG, Techno-economics, Biomass, Earnings, Gas plants, Gasification, Natural gasoline plants, Sulfur compounds, Synthesis gas, Internal rate of return, Molten carbonate, Operational parameters, Pressure and temperature, Synthetic natural gas, Natural gas conditioning
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-236341 (URN)10.1115/1.4040942 (DOI)2-s2.0-85052065806 (Scopus ID)
Funder
Swedish InstituteThe Kempe Foundations
Note

QC 20181109

Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2018-11-09Bibliographically approved
Marks, K., Ghadami Yazdi, M., Piskorz, W., Simonov, K., Stefanuik, R., Sostina, D., . . . Ostrom, H. (2019). Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111). Journal of Chemical Physics, 150(24), Article ID 244704.
Open this publication in new window or tab >>Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111)
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2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 24, article id 244704Article in journal (Refereed) Published
Abstract [en]

The temperature dependent dehydrogenation of naphthalene on Ni(111) has been investigated using vibrational sum-frequency generation spectroscopy, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory with the aim of discerning the reaction mechanism and the intermediates on the surface. At 110 K, multiple layers of naphthalene adsorb on Ni(111); the first layer is a flat lying chemisorbed monolayer, whereas the next layer(s) consist of physisorbed naphthalene. The aromaticity of the carbon rings in the first layer is reduced due to bonding to the surface Ni-atoms. Heating at 200 K causes desorption of the multilayers. At 360 K, the chemisorbed naphthalene monolayer starts dehydrogenating and the geometry of the molecules changes as the dehydrogenated carbon atoms coordinate to the nickel surface; thus, the molecule tilts with respect to the surface, recovering some of its original aromaticity. This effect peaks at 400 K and coincides with hydrogen desorption. Increasing the temperature leads to further dehydrogenation and production of H-2 gas, as well as the formation of carbidic and graphitic surface carbon. 

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-255435 (URN)10.1063/1.5098533 (DOI)000473303200040 ()31255092 (PubMedID)2-s2.0-85068220749 (Scopus ID)
Note

QC 20190820

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-08-20Bibliographically approved
Montecchio, F., Bäbler, M. & Engvall, K. (2018). Development of an irradiation and kinetic model for UV processes in volatile organic compounds abatement applications. Chemical Engineering Journal, 348, 569-582
Open this publication in new window or tab >>Development of an irradiation and kinetic model for UV processes in volatile organic compounds abatement applications
2018 (English)In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 348, p. 569-582Article in journal (Refereed) Published
Abstract [en]

Air pollution from volatile organic compounds (VOCs) is one of the most important environmental hazards. Advanced oxidation processes (AOPs) with UV systems have been showing high potential for the abatement of VOCs. This work is aimed at modeling UV reactors for scaling-up AOPs from lab-scale to full-scale. The proposed model has a novel approach coupling the UV fluence rate to the photo-kinetic mechanism, for a robust understanding of the phenomena involved. The results show that the 185 nm wavelength is deeply absorbed within few centimeters by oxygen, while the 254 nm wavelength is weakly absorbed by the ozone generated in the reactor. Based on the fluence rate calculations, the reactions of ozone generation and depletion were modeled. The ozone net concentration was compared to the experimental results, for model verification. The model accurately predicts the effect of the airflow rate and reactor diameter for the tested cases. The acetaldehyde oxidation reaction was modeled using a simplified kinetic mechanism, using the experimental data of VOC conversion for a further model verification. The suggested reactor models accurately predicted the effect of airflow rate, while exhibiting limitations for the effect of different reactor diameters. Therefore, a computational fluid dynamics (CFD) investigation is needed for an accurate modeling of the VOCs oxidation reaction, implementing the developed analytical expression for reducing the computational workload. By combining the developed model with a CFD simulator, it would be possible to simulate several reactors, also at full-scale, for predicting their performance and identifying optimal configurations.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Air treatment, AOPs, Reaction modeling, Reactor scale-up, UV irradiation, VOCs abatement
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-228697 (URN)10.1016/j.cej.2018.05.009 (DOI)000434467000056 ()2-s2.0-85046649604 (Scopus ID)
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research
Note

QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-08-18Bibliographically approved
Wan, W., Engvall, K., Yang, W. & Möller, B. F. (2018). Experimental and modelling studies on condensation of inorganic species during cooling of product gas from pressurized biomass fluidized bed gasification. Energy, 153, 35-44
Open this publication in new window or tab >>Experimental and modelling studies on condensation of inorganic species during cooling of product gas from pressurized biomass fluidized bed gasification
2018 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 153, p. 35-44Article in journal (Refereed) Published
Abstract [en]

In a biomass gasification process, condensation of inorganic species can cause problems such as corrosion and deposition on the downstream equipment. In this work, in order to investigate the condensation of inorganics during the gas cooling step of the biomass gasification system, both experimental and modelling studies were conducted. Experiments were performed on a pilot-scale steam/oxygen blown fluidized bed gasification facility. A CO2 cooled probe was located at the head of a filter to condense inorganic species. Five thermocouples were used to monitor the probe temperature profile. Deposits on the probe were characterized using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to analyze the elemental composition of deposits. A process model based on the local chemical and phase equilibriums was developed using software SimuSage to predict both release and condensation of inorganics. A customized thermodynamic database extracted from the FactSage 7.1 was used during model calculations. Two cases including with and without addition of bed material were calculated. Results show that the identified elemental compositions of deposit under different gas cooling temperatures reasonably agree with the elemental compositions predicted by model calculations. This demonstrates that the established model and the customized thermodynamic data are valid. A large amount of carbon is identified in the deposit of low temperature probe sections, which may come from the condensed tar. Additionally, a temperature window is found, where melts are formed during gas cooling.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Biomass, Inorganics, Condensation, Gasification
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-234209 (URN)10.1016/j.energy.2018.04.031 (DOI)000436651100005 ()2-s2.0-85046675283 (Scopus ID)
Note

QC 20180905

Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-11-29Bibliographically approved
Wan, W., Engvall, K. & Weihong, Y. (2018). Model investigation of condensation behaviors of alkalis during syngas treatment of pressurized biomass gasification. Chemical Engineering and Processing, 129, 28-36
Open this publication in new window or tab >>Model investigation of condensation behaviors of alkalis during syngas treatment of pressurized biomass gasification
2018 (English)In: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 129, p. 28-36Article in journal (Refereed) Published
Abstract [en]

In order to eliminate problems such as corrosion and ash deposition caused by alkalis, effects of the biomass composition and the pressure of syngas in the downstream process on condensation of alkalis in a wood steam/oxygen blown fluidized bed gasification process are investigated based on a model. This model is established by combining Aspen Plus with SimuSage. Aspen Plus is applied to predict the composition of major gas species formed by C, H, O, N, S and Cl, using empirical correlations to predict the yields of non-equilibrium substances. SimuSage is used to study the release and condensation of inorganics associated with the minor elements (Al, Ca, Fe, K, Mg, Na, P, Si and Ti) based on a customized thermodynamic database. Results show that carbonation reactions between alkalis and CO/CO2 can be occurred during gas cooling, leading to form alkali carbonates in the condensed phase. The temperature window forming melts varies with the change of the downstream pressure of syngas and the elemental composition of biomass. As the syngas pressure in the downstream process decreases, the initial temperature of forming melts during gas cooling is reduced. For biomass lower in K/Cl ratio, the condensate with the largest mass formed during gas cooling is potassium chloride. The condensation rate of Cl increases with the decrease of the K/Cl ratio in biomass.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Alkali metal, Biomass, Condensation, Gasification
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-228721 (URN)10.1016/j.cep.2018.05.001 (DOI)000435059000004 ()2-s2.0-85046685389 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-07-02Bibliographically approved
Musavi, Z., Kusar, H., Andersson, R. & Engvall, K. (2018). Modelling and optimization of a small diesel burner for mobile applications. Energies, 11(11), Article ID 2904.
Open this publication in new window or tab >>Modelling and optimization of a small diesel burner for mobile applications
2018 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 11, article id 2904Article in journal (Refereed) Published
Abstract [en]

While extensive research has been done on improving diesel engines, much less has been done on auxiliary heaters, which have their own design challenges. The study analyzes how to optimize the combustion performance of an auxiliary heater, a 6 kW diesel burner, by investigating key parameters affecting diesel combustion and their properties. A model of a small diesel heater, including a simulation of fuel injection and combustion process, was developed step-wise and verified against experimental results that can be used for scaling up to 25 kW heaters. The model was successfully applied to the burner, predicting the burner performance in comparison with experimental results. Three main variables were identified as important for the design. First, it was concluded that the distance from the ring cone to the nozzle is essential for the fluid dynamics and flame location, and that the ring cone should be moved closer to the nozzle for optimal performance. Second, the design of the swirl co-flow is important, and the swirl number of the inlet air should be kept above 0.6 to stabilize the flame location for the present burner design. Finally, the importance of the nozzle diameter to avoid divergent particle vaporization was pointed out.

Place, publisher, year, edition, pages
MDPI AG, 2018
Keywords
CFD modelling, Design optimization, Diesel combustion, NOx emission, Nozzle diameter, Swirl number, Combustion, Computational fluid dynamics, Nozzle design, Nozzles, NOx emissions, Swirl numbers, Diesel engines
National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-247085 (URN)10.3390/en11112904 (DOI)000451814000042 ()2-s2.0-85057841817 (Scopus ID)
Note

QC 20190503

Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-05-03Bibliographically approved
Wan, W., Engvall, K. & Weihong, Y. (2018). Novel Model for the Release and Condensation of Inorganics for a Pressurized Fluidized-Bed Gasification Process: Effects of Gasification Temperature. ACS OMEGA, 3(6), 6321-6329
Open this publication in new window or tab >>Novel Model for the Release and Condensation of Inorganics for a Pressurized Fluidized-Bed Gasification Process: Effects of Gasification Temperature
2018 (English)In: ACS OMEGA, ISSN 2470-1343, Vol. 3, no 6, p. 6321-6329Article in journal (Refereed) Published
Abstract [en]

A model is established to investigate the release and condensation of inorganics for a wood steam/oxygen-blown fluidized-bed gasification process. In the established model, fates of major elements (C, H, O, N, S, and Cl) and minor elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti, and Zn) are modeled separately. The composition of gaseous species involving major elements is predicted using Aspen Plus based on a semiempirical model. The release of minor elements and the condensation of inorganics are predicted using software SimuSage. The combination of Aspen Plus with SimuSage is achieved by manually inputting the stream parameters calculated from Aspen Plus into SimuSage. On the basis of this developed model, effects of gasification temperature on the condensation of Na-, K-, and Cl-containing species during gas cooling are studied. Results show that the process model established by combining Aspen Plus and SimuSage is valid and can be used to investigate the release of inorganics during gasification and condensation of inorganics during gas cooling. Under the investigated gasification conditions, regardless of the bed material, there are two temperature ranges within which no salt melt is formed during gas cooling. As the gasification temperature increases, the high-temperature range without salt melt formation becomes successively wider.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-232415 (URN)10.1021/acsomega.8b00019 (DOI)000436340500045 ()2-s2.0-85046646445 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180726

Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26Bibliographically approved
H. Moud, P., Kantarelis, E., J. Andersson, K. & Engvall, K. (2017). Biomass pyrolysis gas conditioning over an iron-based catalyst for mild deoxygenation and hydrogen production. Fuel, 211, 149-158
Open this publication in new window or tab >>Biomass pyrolysis gas conditioning over an iron-based catalyst for mild deoxygenation and hydrogen production
2017 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 211, p. 149-158Article in journal (Other academic) Published
Abstract [en]

Bio-crude is a renewable source for production of valuable energy carriers. Prior to its utilization, a conditioning step of the raw pyrolysis gas can be beneficial before the bio-crude is converted via catalytic hydrodeoxygenation (HDO) into liquid hydrocarbon products, or via steam reforming (SR) to synthesis gas/hydrogen. An experimental small industrial scale study for the chemistry of atmospheric pressure pyrolysis gas conditioning resulting in bio-crude deoxygenation and a hydrogen-rich gas using an iron-based catalyst without addition of hydrogen or steam is presented and discussed. Following a short catalyst stabilization period with fluctuating bed temperatures, the catalyst operated near 450°C at a space velocity of 1100 h-1 for 8 hours under stable conditions during which no significant catalyst deactivation was observed. Experimental results indicate a 70-80% reduction of acetic acid, methoxy phenols, and catechol, and a 55-65% reduction in non-aromatic ketones, BTX, and heterocycles. Alkyl phenols and phenols were least affected, showing a 30-35% reduction. Conditioning of the pyrolysis gas resulted in a 56 % and a 18 wt% increase in water and permanent (dry) gas yield, respectively, and a 29 % loss of condensable carbon. A significant reduction of CO amount (-38 %), and production of H2 (+1063 %) and CO2 (+36 %) over the catalyst was achieved, while there was no or minimal change in light hydrocarbon content. Probing the catalyst after the test, the bulk phase of the catalyst was found to be magnetite (Fe3O4) and the catalyst exhibited significant water gas shift (WGS) reaction activity. The measured gas composition during the test was indicative of no or very limited Fischer-Tropsch (FT) CO /CO2 hydrogenation activity and this infers that also the active surface phase of the catalyst during the test was Fe-oxide, rather than Fe-carbide. The results show that iron-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way of generating a hydrogen-enriched gas without the need for bio-crude condensation.

Keywords
Bio-crude conditioning, bio-crude upgrading, gas conditioning, deoxygenation, water-gas shift
National Category
Other Chemical Engineering Other Chemistry Topics
Research subject
Chemical Engineering; Chemistry
Identifiers
urn:nbn:se:kth:diva-213136 (URN)10.1016/j.fuel.2017.09.062 (DOI)000413449600017 ()2-s2.0-85029589987 (Scopus ID)
Projects
Energiforsk
Funder
Swedish Energy Agency
Note

QC 20170830

Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-11-14Bibliographically approved
Mesfun, S., Lundgren, J., Toffolo, A., Lindbergh, G., Lagergren, C. & Engvall, K. (2017). Integration of an electrolysis unit for producer gas conditioning in a bio-SNG plant. In: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017: . Paper presented at 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017.
Open this publication in new window or tab >>Integration of an electrolysis unit for producer gas conditioning in a bio-SNG plant
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2017 (English)In: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Producer gas from biomass gasification contains impurities like tars, particles, alkali salts and sulfur/nitrogen compounds. As a result a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into SNG. A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of tailored syngas produced. Investment opportunity is evaluated as an economic indicator of the processes considered. Results indicate that the production of SNG can be boosted by approximately 50% without the need of an additional carbon source, i.e. for the same biomass input as in standalone operation of the GoBiGas plant.

National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-233923 (URN)2-s2.0-85048615505 (Scopus ID)
Conference
30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017
Note

cited By 0. QC 20181003

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-10-03Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-6326-4084

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