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Thorin, E., Sepman, A., Carlborg, M., Wiinikka, H. & Schmidt, F. M. (2025). Oxy-fuel combustion of softwood in a pilot-scale down-fired pulverized combustor – Fate of potassium. Fuel, 381, Article ID 133485.
Open this publication in new window or tab >>Oxy-fuel combustion of softwood in a pilot-scale down-fired pulverized combustor – Fate of potassium
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2025 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 381, article id 133485Article in journal (Refereed) Published
Abstract [en]

Oxy-fuel biomass combustion can facilitate carbon capture in heat and power plants and enable negative carbon dioxide (CO2) emissions. We demonstrate oxy-fuel combustion (OFC) of softwood powder in a 100-kW atmospheric down-fired pulverized combustor run at a global oxidizer-fuel equivalence ratio of around 1.25. The simulated oxidizer was varied between oxygen (O2)/CO2 mixtures of 23/77, 30/70, 40/60 and 54/46, and artificial air. The concentrations of the main gaseous potassium (K) species: atomic K, potassium hydroxide (KOH) and potassium chloride (KCl), were measured at two positions in the reactor core using photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS). Major species were quantified by TDLAS in the reactor core and with Fourier transform infrared spectroscopy and mass spectrometry at the exhaust. Flue gas particles were collected at the exhaust employing a low-pressure impactor and analyzed by X-ray powder diffraction and scanning electron microscopy. The measured individual K species concentrations in the reactor core agreed with predictions by thermodynamic equilibrium calculations (TEC) within one order of magnitude and the sum of K in the gas phase agreed within a factor of three for all cases. Atomic K was underpredicted, while the dominating KOH and KCl were slightly overpredicted. The ratios of measured to predicted total K were similar in artificial air and OFC, but the distributions of the individual species differed at the upper reactor position. The gaseous K species and fine particle concentrations in the flue gas were directly proportional to the O2 content in the oxidizer. The crystalline phase compositions of the coarse mode particles were rich in K- and calcium-containing species. The fine mode particles, which contained most of the K, consisted mainly of K2SO4 (94%) and K3Na(SO4)2, which is in excellent agreement with TECs of gas phase condensation. As supported by the solid phase analysis, complete sulfation of K species was achieved for all studied cases. A CO2 purity (dry) of up to 94% was achieved for OFC. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2025
Keywords
Antiknock compounds; Bioremediation; Bottoming cycle systems; Coal; Explosives detection; Fourier transform infrared spectroscopy; Liquid chromatography; Photoelectron spectroscopy; Photolysis; Potassium chloride; Pulse repetition rate; Radioactivation analysis; Steam; Supersonic aerodynamics; Wood fuels; X ray powder diffraction; Biomass combustion; Heat and power plants; Oxy-fuels; Oxyfuel combustion; Pilot scale; Potassium (K); Potassium chloride; Pulverized combustions; Scale-down; Sulphation; Potassium hydroxide
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-76169 (URN)10.1016/j.fuel.2024.133485 (DOI)2-s2.0-85207600325 (Scopus ID)
Note

The authors acknowledge financial support from the Swedish Energy Agency and the Kempe Foundations. The long-term support from the Swedish Strategic Research Environment Bio4Energy for our activities is highly appreciated.

Available from: 2024-11-22 Created: 2024-11-22 Last updated: 2024-11-22Bibliographically approved
Johansson, A., Fernberg, J., Sepman, A., Colin, S., Wennebro, J., Normann, F. & Wiinikka, H. (2024). Cofiring of hydrogen and pulverized coal in rotary kilns using one integrated burner. International journal of hydrogen energy, 90, 342-352
Open this publication in new window or tab >>Cofiring of hydrogen and pulverized coal in rotary kilns using one integrated burner
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2024 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 90, p. 342-352Article in journal (Refereed) Published
Abstract [en]

The grate-kiln process for iron-ore pellet induration utilizes pulverized coal fired burners. In a developed infrastructure for H2, it might be desirable to heat the existing rotary kilns with renewably produced H2. Technical challenges of H2 heating of grate-kilns include high emissions of NOX and maintaining sufficient heat transfer to the pellet bed. This article examined cofiring (70% coal/30% H2) in 130 kW experiments using two different integrated burner concepts. Compared to pure coal combustion, cofiring creates a more intense, smaller flame with earlier ignition and less fluctuations. The process temperature and heat transfer are enhanced in the beginning of the kiln. The co-fired flames emit 32% and 78% less NOX emissions compared to pure coal and H2 combustion, respectively. We can affect the combustion behavior and NOX emissions by the burner design. H2/coal cofiring using integrated burners is probably an attractive solution for emission minimization in rotary kilns.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Coal, Coal combustion, Coal fueled furnaces, Iron ore pellets, Pulverized fuel, Co-firing, Combustion behaviours, Emission, Hydrogen combustion, Pellet induration, Process heat, Process temperature, Pulverized coal fired burner, Pulverized coals, Technical challenges, Rotary kilns
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-76031 (URN)10.1016/j.ijhydene.2024.09.327 (DOI)2-s2.0-85205469308 (Scopus ID)
Funder
Swedish Energy Agency, P2022-00196
Note

The authors gratefully acknowledge Luossavaara-Kiirunavaara AB (LKAB), the Swedish Energy Agency and the European Union (EU) for the financial support of this work (P2022-00196). Additionally, all experimental support provided from our colleagues Niklas Mörtlund, Therese Vikström, Sandra Lundström and others at RISE, Piteå is greatly appreciated.

Available from: 2024-11-01 Created: 2024-11-01 Last updated: 2024-11-01Bibliographically approved
Ögren, Y., Sepman, A., Fooladgar, E., Weiland, F. & Wiinikka, H. (2024). Development and evaluation of a vision driven sensor for estimating fuel feeding rates in combustion and gasification processes. Energy and AI, 15, Article ID 100316.
Open this publication in new window or tab >>Development and evaluation of a vision driven sensor for estimating fuel feeding rates in combustion and gasification processes
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2024 (English)In: Energy and AI, ISSN 2666-5468, Vol. 15, article id 100316Article in journal (Refereed) Published
Abstract [en]

A machine vision driven sensor for estimating the instantaneous feeding rate of pelletized fuels was developed and tested experimentally in combustion and gasification processes. The feeding rate was determined from images of the pellets sliding on a transfer chute into the reactor. From the images the apparent area and velocity of the pellets were extracted. Area was determined by a segmentation model created using a machine learning framework and velocities by image registration of two subsequent images. The measured weight of the pelletized fuel passed through the feeding system was in good agreement with the weight estimated by the sensor. The observed variations in the fuel feeding correlated with the variations in the gaseous species concentrations measured in the reactor core and in the exhaust. Since the developed sensor measures the ingoing fuel feeding rate prior to the reactor, its signal could therefore help improve process control. 

Place, publisher, year, edition, pages
Elsevier B.V., 2024
Keywords
Combustion, Fuel feeding, Gasification, Image processing, Neural network, Process monitoring, Feeding, Image segmentation, Pelletizing, Process control, Combustion pro-cess, Feeding rate, Gasification process, Images processing, Machine-learning, Machine-vision, Neural-networks, Segmentation models, Transfer chutes
National Category
Environmental Engineering
Identifiers
urn:nbn:se:ri:diva-71916 (URN)10.1016/j.egyai.2023.100316 (DOI)2-s2.0-85181658798 (Scopus ID)
Funder
Swedish Energy Agency, 50470-1Swedish Research Council FormasVinnovaEU, Horizon 2020, 818011
Note

Correspondence Address: Y. Ögren; RISE AB, Piteå, Box 726 SE-941 28, Sweden; . The Bio4Energy, a strategic research environment appointed by the Swedish government and the SwedishCenter for Gasification financed by the Swedish Energy Agency and member companies. The RE:source program finance by the Swedish Energy Agency, Vinnova and Formas. The Pulp&Fuel project financed by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 818011 and the TDLAS-AI project (Swedish energy agency project 50470-1). 

Available from: 2024-02-22 Created: 2024-02-22 Last updated: 2024-02-22Bibliographically approved
Sepman, A., Wennebro, J., Fernberg, J. & Wiinikka, H. (2024). Following fuel conversion during biomass gasification using tunable diode laser absorption spectroscopy diagnostics. Fuel, 374, Article ID 132374.
Open this publication in new window or tab >>Following fuel conversion during biomass gasification using tunable diode laser absorption spectroscopy diagnostics
2024 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 374, article id 132374Article in journal (Refereed) Published
Abstract [en]

The efficiency of the gasification process and product quality largely depend on the degree of fuel conversion. We present the real-time in-situ tunable diode laser measurements of main carbon and oxygen-containing species in the hot reactor core of a pilot-scale entrained flow biomass gasifier (EFG). The concentrations of CO, CO2, CH4, C2H2, H2O, soot, and gas temperature were measured during the air and oxygen-enriched gasification of stem wood at varying equivalence ratios. The experiments were made at the upper and lower optical ports inside a 4 m long, ceramic-lined, atmospheric EFG, allowing to access the degree of the fuel conversion inside the reactor. The exhaust composition was measured by micro-GC, FTIR, and low-pressure impactor. There was a good agreement between the data measured inside the reactor and at the exhaust for oxygen-enriched gasification implying that the chemical reactions are practically frozen downstream the optical ports. For air, the data indicated that the gasification reactions are still active at the measurement locations. Significant concentrations of C2H2, up to 5000 ppm, were found inside the reactor. 

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Absorption spectroscopy, Biomass, Fourier transform infrared spectroscopy, Laser diagnostics, Oxygen, Semiconductor lasers, Biomass Gasification, Biomass gasifier, Entrained flow, Fuel conversion, Gasification process, Gasification products, Optical ports, Oxygen-enriched, TDLAS, Tunable diode laser absorption spectroscopy, Gasification
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-74710 (URN)10.1016/j.fuel.2024.132374 (DOI)2-s2.0-85197599780 (Scopus ID)
Funder
Swedish Energy Agency, 50470-1
Note

We gratefully acknowledge financial support from the Swedish Energy Agency through 50470-1 project.

Available from: 2024-08-08 Created: 2024-08-08 Last updated: 2024-08-08
Sepman, A., Malhotra, J. S., Wennebro, J. & Wiinikka, H. (2024). Iron as recyclable electrofuel: Effect on particle morphology from multiple combustion-regeneration cycles. Combustion and Flame, 259, Article ID 113137.
Open this publication in new window or tab >>Iron as recyclable electrofuel: Effect on particle morphology from multiple combustion-regeneration cycles
2024 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 259, article id 113137Article in journal (Refereed) Published
Abstract [en]

This work describes the morphological and material changes in the iron powder during four regeneration-combustion cycles. The regeneration in H2 and combustion in air experiments were made in a fluidized bed (FB) and an entrained flow reactor (EFR), respectively. The average size of the iron oxide particles more than doubled between the first and fourth combustion cycles, and many of the particles were hollow. The regeneration step did not change the size of the particles but increased their porosity. A mechanism is proposed that describes the formation of large-diameter hollow particles which increases as a function of the regeneration-combustion cycles. The observed increase in particle size and the change in particle morphology complicates the iron fuel concept, as it leads to a degradation of the structural stability of the particle with time.

Place, publisher, year, edition, pages
Elsevier Inc., 2024
Keywords
Fluidized bed combustion; Fluidized beds; Iron oxides; Morphology; Particle size; Air experiments; Average size; Combustion cycle; Entrained Flow Reactor; Iron oxide particles; Material change; Morphological changes; Particle morphologies; Recyclables; Regeneration cycles; Stability
National Category
Energy Engineering Other Environmental Engineering
Identifiers
urn:nbn:se:ri:diva-67706 (URN)10.1016/j.combustflame.2023.113137 (DOI)2-s2.0-85174581752 (Scopus ID)
Available from: 2023-11-06 Created: 2023-11-06 Last updated: 2024-05-17Bibliographically approved
Fooladgar, E., Sepman, A., Ögren, Y., Johansson, A., Gullberg, M. & Wiinikka, H. (2024). Low-NOx thermal plasma torches: A renewable heat source for the electrified process industry. Fuel, 378, Article ID 132959.
Open this publication in new window or tab >>Low-NOx thermal plasma torches: A renewable heat source for the electrified process industry
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2024 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 378, article id 132959Article in journal (Refereed) Published
Abstract [en]

Industrial thermal plasma torches can heat a gas up to 5000–20,000 K, i.e., well above the temperature needed to replace the heat generated from the combustion of traditional fossil fuels (e.g., coal, oil, and natural gas) in large-scale process industry furnaces producing construction materials (e.g., iron, steel, lime, and cement). However, there is a risk for significant NOx emissions when air or N2 are used as plasma-forming gas since the temperature somewhere in the furnace always will be higher compared to the threshold NOx formation temperature of ∼1800 K. Torch NOx forms inside the high temperature region of the plasma torch (>5000 K) when air is used as gas. Process NOx forms instead when the hot gas (when air or nitrogen is used as plasma forming gas) from the plasma torch mixes with process air downstream the torch. By analysing the complex chemistry of both the torch- and process NOx formation with thermodynamic equilibrium and one-dimensional chemical kinetic calculations it was shown that adding H2 to the plasma-forming N2 gas significantly reduces the NOx emissions with more than 90 %. Verifying experiments with air, pure N2, and mixtures of H2 and N2 as plasma-forming gas were performed in a laboratory scale insulated laboratory furnace with different pre-heating temperatures of process air (293, 673, and 1073 K) which the plasma gas mixes with downstream the torch. Depending on the pre-heating temperature the NOx emissions were between 12,000–14,000 mg NO2/MJfuel when air was used as plasma forming gas. Substantial NOx emission reduction occurs both when N2 replaces air, where the NOx emissions was in the span of 8000–11,500 mg NO2/MJfuel and furthermore when H2 was mixed into the N2 gas stream. For the highest degree of H2 mixing (28.6 vol-%), the NOx emissions were between 450–1700 mg NO2/MJfuel depending on the pre-heat temperature of the process air, i.e., a reduction of 88–96 % and 85–94 %, respectively when air or N2 was used as plasma forming gas. The measured NOx emissions are then of the same order of magnitude as would be expected from the combustion of traditional fuels (coal, oil, biomass and pure H2). Finally, by analysing the aerodynamics in an axisymmetric furnace with an experimentally validated computational fluid dynamics (CFD) model using reduced chemistry for the NOx formation (19 species and 70 reactions), further guidelines into the process of NOx reduction from thermal plasma torches are given. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
Keywords
Catalytic cracking; Coal combustion; Coal industry; Coal oil mixtures; Lignite; Melt spinning; Metal casting; Metal castings; Natural gas wells; Oil shale; Petroleum tar; Pipelines; Plasma welding; Preheating; Putty; Steelmaking furnaces; Wire drawing; Down-stream; Nitrogen oxide emissions; NO 2; NO x; NO x emission; Plasma forming gas; Pre-heating; Process industries; Thermal plasma; Thermal plasma torch; Plasma torches
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-74989 (URN)10.1016/j.fuel.2024.132959 (DOI)2-s2.0-85202556500 (Scopus ID)
Note

This work was conducted as part of the Hydrogen Breakthrough Ironmaking Technology (HYBRIT) research project RP1. The Swedish Energy Agency is acknowledged for financial support of HYRIT. HYBRIT is a joint initiative of SSAB, LKAB, and Vattenfall with the aim of developing the world’s first fossil-fuel-free ore-based steelmaking route. Sofia Nordqvist (LKAB/HYBRIT), Christian Fredriksson (LKAB), and Fredrik Normann (LKAB/Chalmers Technical University) are also acknowledged for their constructive suggestions

Available from: 2024-09-09 Created: 2024-09-09 Last updated: 2024-09-09Bibliographically approved
Siddanathi, S. L., Westerberg, L. G., Åkerstedt, H., Wiinikka, H. & Sepman, A. (2023). Computational modeling and temperature measurements using emission spectroscopy on a non-transferred plasma torch. AIP Advances, 13(2), Article ID 025019.
Open this publication in new window or tab >>Computational modeling and temperature measurements using emission spectroscopy on a non-transferred plasma torch
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2023 (English)In: AIP Advances, E-ISSN 2158-3226, Vol. 13, no 2, article id 025019Article in journal (Refereed) Published
Abstract [en]

A non-transferred plasma torch is a device used to generate a steady thermal plasma jet. Plasma torches have the potential to replace fossil fuel burners used as heat sources in the process industry. Today, however, the available plasma torches are of small scale compared to the power used in the burners in the process industry. In order to understand the effects of large scales on the plasma flow dynamics, it is essential to understand the operation of the plasma torch under different operating conditions and for different geometries. In this study, the analysis of a non-transferred plasma torch has been carried out using both computational and experimental methods. Computationally, the magnetohydrodynamic (MHD) equations are solved using a single-fluid model on a 2D axisymmetric torch geometry. The experiments are performed using emission spectroscopy to measure the plasma jet temperature at the outlet. This paper explains the changes in the arc formation, temperature, and velocity for different working gases and power inputs. Furthermore, the possibilities and disadvantages of the MHD approach, considering a local thermal equilibrium, are discussed. It was found that in general, the computational temperature obtained is supported by the experimental and equilibrium data. The computational temperatures agree by within 10% with the experimental ones at the center of the plasma torch. The paper concludes by explaining the significant impact of input properties like working gas and power input on the output properties like velocity and temperature of plasma jet. © 2023 Author(s).

Place, publisher, year, edition, pages
American Institute of Physics Inc., 2023
Keywords
Emission spectroscopy, Fossil fuels, Magnetohydrodynamics, Plasma diagnostics, Plasma jets, Temperature measurement, Computational modelling, Gas input, Heat sources, Large-scales, Power, Power input, Process industries, Small scale, Thermal plasma jets, Working gas, Plasma torches
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-64103 (URN)10.1063/5.0129653 (DOI)2-s2.0-85147798595 (Scopus ID)
Note

Funding details: Energimyndigheten, 49609-1; Funding text 1: This work was funded by the Swedish Energy Agency, Grant No. 49609-1.

Available from: 2023-02-28 Created: 2023-02-28 Last updated: 2023-05-19Bibliographically approved
Mousavi, S. M., Thorin, E., Schmidt, F. M., Sepman, A., Bai, X. S. & Fatehi, H. (2023). Numerical Study and Experimental Verification of Biomass Conversion and Potassium Release in a 140 kW Entrained Flow Gasifier. Energy & Fuels, 37(2), 1116-1130
Open this publication in new window or tab >>Numerical Study and Experimental Verification of Biomass Conversion and Potassium Release in a 140 kW Entrained Flow Gasifier
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2023 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 37, no 2, p. 1116-1130Article in journal (Refereed) Published
Abstract [en]

In this study, a Eulerian-Lagrangian model is used to study biomass gasification and release of potassium species in a 140 kW atmospheric entrained flow gasifier (EFG). Experimental measurements of water concentration and temperature inside the reactor, together with the gas composition at the gasifier outlet, are used to validate the model. For the first time, a detailed K-release model is used to predict the concentrations of gas-phase K species inside the gasifier, and the results are compared with experimental measurements from an optical port in the EFG. The prediction errors for atomic potassium (K), potassium chloride (KCl), potassium hydroxide (KOH), and total potassium are 1.4%, 9.8%, 5.5%, and 5.7%, respectively, which are within the uncertainty limits of the measurements. The numerical model is used to identify and study the main phenomena that occur in different zones of the gasifier. Five zones are identified in which drying, pyrolysis, combustion, recirculation, and gasification are active. The model was then used to study the transformation and release of different K species from biomass particles. It was found that, for the forest residue fuel that was used in the present study, the organic part of K is released at the shortest residence time, followed by the release of inorganic K at higher residence times. The release of inorganic salts starts by evaporation of KCl and continues by dissociation of K2CO3 and K2SO4, which forms gas-phase KOH. The major fraction of K is released around the combustion zone (around 0.7-1.3 m downstream of the inlet) due to the high H2O concentration and temperature. These conditions lead to rapid dissociation of K2CO3 and K2SO4, which increases the total K concentration from 336 to 510 ppm in the combustion zone. The dissociation of the inorganic salts and KOH formation continues in the gasification zone at a lower rate; hence, the total K concentration slowly increases from 510 ppm at 1.3 m to 561 ppm at the outlet. © 2023 The Authors. 

Place, publisher, year, edition, pages
American Chemical Society, 2023
Keywords
Chlorine compounds, Combustion, Dissociation, Forestry, Gases, Gasification, Potassium hydroxide, Salts, Biomass conversion, Combustion zones, Entrained flow gasifiers, Eulerian Lagrangian models, Experimental verification, Gas-phases, Gasifiers, Inorganic salts, Potassium release, Residence time, Biomass
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-62973 (URN)10.1021/acs.energyfuels.2c03107 (DOI)2-s2.0-85146130812 (Scopus ID)
Note

Funding details: 22538-4; Funding details: 36160-1, 50470-1; Funding details: College of Science, Technology, Engineering, and Mathematics, Youngstown State University, STEM; Funding details: Knut och Alice Wallenbergs Stiftelse; Funding details: Energimyndigheten; Funding details: Kempestiftelserna, JCK-1316; Funding details: Horizon 2020, 637020; Funding text 1: This work was supported by the Swedish Energy Agency (STEM) through KC-CECOST, project No. 22538-4, the Swedish Gasification center, project No. 50470-1, project No. 36160-1, and the Knut & Alice Wallenberg foundation (KAW COCALD project). The authors also acknowledge the financial support from the Swedish strategic research program Bio4Energy and the Kempe Foundations (project JCK-1316). The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at PDC (Dardel). The fuels were received from a project which received funding from the European Unions Horizon 2020 research and innovation program under grant agreement no. 637020 Mobile Flip.

Available from: 2023-01-25 Created: 2023-01-25 Last updated: 2023-07-06Bibliographically approved
Thorin, E., Sepman, A., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. M. (2023). Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier. Proceedings of the Combustion Institute, 39(1), 1337-1345
Open this publication in new window or tab >>Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier
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2023 (English)In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704, Vol. 39, no 1, p. 1337-1345Article in journal (Refereed) Published
Abstract [en]

Photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) was used to simultaneously measure the concentrations of gas phase atomic potassium (K), potassium hydroxide (KOH) and potassium chloride (KCl) in the reactor core of a 140 kWth atmospheric entrained-flow gasifier (EFG). In two gasification experiments at air-to-fuel equivalence ratio of 0.5, the EFG was first run on forest residues (FR) and then on an 80/20 mixture of FR and wheat straw (FR/WS). Combustion at air-to-fuel equivalence ratio of 1.3 was investigated for comparison. A high K(g) absorbance was observed in gasification, requiring the photofragmentation signals from KOH(g) and KCl(g) to be recorded at a fixed detuning of 7.3 cm-1 from the center of the K(g) absorption profile. In combustion, the fragments recombined instantly after the UV pulse within around 10 μs, whereas in gasification, the K(g) fragment concentration first increased further for 30 μs after the UV pulse, before slowly decaying for up to hundreds of μs. According to 0D reaction kinetics simulations, this could be explained by a difference in recombination kinetics, which is dominated by oxygen reactions in combustion and by hydrogen reactions in gasification. The K species concentrations in the EFG were stable on average, but periodic short-term variations due to fuel feeding were observed, as well as a gradual increase in KOH(g) over the day as the reactor approached global equilibrium. A comparison of the average K species concentrations towards the end of each experiment showed a higher total K in the gas phase for FR/WS, with higher K(g) and KCl(g), but lower KOH(g), compared to the FR fuel. The measured values were in reasonable agreement with predictions by thermodynamic equilibrium calculations. © 2022 The Author(s). 

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Biomass, Entrained-flow gasification, Photofragmentation, Potassium (K), Tunable diode laser absorption spectroscopy (TDLAS), Absorption spectroscopy, Combustion, Fuels, Gases, Gasification, Potassium hydroxide, Reaction kinetics, Semiconductor lasers, Entrained flow gasification, Entrained flow gasifiers, Equivalence ratios, Forest residue, Gas-phases, Potassium chloride, Tunable diode laser absorption spectroscopy, Chlorine compounds
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-61456 (URN)10.1016/j.proci.2022.07.180 (DOI)2-s2.0-85139508080 (Scopus ID)
Note

 Funding details: 36160-1, 50470-1; Funding details: Energimyndigheten; Funding details: Kempestiftelserna, JCK-1316; Funding details: Horizon 2020, 637020; Funding text 1: The authors acknowledge financial support from the Swedish strategic research program Bio4Energy, the Kempe Foundations ( JCK-1316 ), and the Swedish Energy Agency through both the Swedish Gasification Centre and projects no. 50470-1 and 36160-1 . The fuels were received from a project which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 637020 - Mobile Flip.

Available from: 2022-12-07 Created: 2022-12-07 Last updated: 2024-05-17Bibliographically approved
Sepman, A., Thorin, E., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. (2022). Laser-based detection of methane and soot during entrained-flow biomass gasification. Combustion and Flame, 237, Article ID 111886.
Open this publication in new window or tab >>Laser-based detection of methane and soot during entrained-flow biomass gasification
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2022 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 237, article id 111886Article in journal (Refereed) Published
Abstract [en]

Methane is one of the main gas species produced during biomass gasification and may be a desired or undesired product. Syngas CH4 concentrations are typically >5 vol-% (when desired) and 1–3 vol-% even when efforts are made to minimize it, while thermochemical equilibrium calculations (TEC) predict complete CH4 decomposition. How CH4 is generated and sustained in the reactor core is not well understood. To investigate this, accurate quantification of the CH4 concentration during the process is a necessary first step. We present results from rapid in situ measurements of CH4, soot volume fraction, H2O and gas temperature in the reactor core of an atmospheric entrained-flow biomass gasifier, obtained using tunable diode laser absorption spectroscopy (TDLAS) in the near-infrared (1.4 µm) and mid-infrared (3.1 µm) region. An 80/20 wt% mixture of forest residues and wheat straw was converted using oxygen-enriched air (O2>21 vol%) as oxidizer, while the global air-fuel equivalence ratio (AFR) was set to values between 0.3 and 0.7. Combustion at AFR 1.3 was performed as a reference. The results show that the CH4 concentration increased from 1 to 3 vol-% with decreasing AFR, and strongly correlated with soot production. In general, the TDLAS measurements are in good agreement with extractive diagnostics at the reactor outlet and TEC under fuel-lean conditions, but deviate significantly for lower AFR. Detailed 0D chemical reaction kinetics simulations suggest that the CH4 produced in the upper part of the reactor at temperatures >1700 K was fully decomposed, while the CH4 in the final syngas originated from the pyrolysis of fuel particles at temperatures below 1400 K in the lower section of the reactor core. It is shown that the process efficiency was significantly reduced due to the C and H atoms bound in methane and soot. © 2021 The Authors

Place, publisher, year, edition, pages
Elsevier Inc., 2022
Keywords
Biomass, Entrained-flow reactor, Gasification, Methane, Soot, Tunable diode laser absorption spectroscopy (TDLAS), Absorption spectroscopy, Atmospheric movements, Atmospheric temperature, Dust, Infrared devices, Reaction kinetics, Semiconductor lasers, Surface reactions, Synthesis gas, Air/fuel equivalence ratio, Biomass Gasification, CH 4, Entrained flow, Entrained Flow Reactor, Equilibrium calculation, Syn gas, Thermochemical equilibrium, Tunable diode laser absorption spectroscopy
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-57326 (URN)10.1016/j.combustflame.2021.111886 (DOI)2-s2.0-85120458898 (Scopus ID)
Note

 Funding details: 50470-1; Funding details: Energimyndigheten; Funding details: Horizon 2020, 637020; Funding text 1: The authors acknowledge financial support from the Swedish strategic research program Bio4Energy and the Swedish Energy Agency through both the Swedish Gasification Centre and project no. 50470-1. The fuels were received from a project, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 637020 - Mobile Flip.

Available from: 2021-12-16 Created: 2021-12-16 Last updated: 2024-05-17Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2253-6845

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