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Carlborg, M., Weiland, F., Ma, C., Backman, R., Landälv, I. & Wiinikka, H. (2018). Exposure of refractory materials during high-temperature gasification of a woody biomass and peat mixture. Journal of the European Ceramic Society, 38(2), 777-787
Open this publication in new window or tab >>Exposure of refractory materials during high-temperature gasification of a woody biomass and peat mixture
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2018 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 38, no 2, p. 777-787Article in journal (Refereed) Published
Abstract [en]

Finding resilient refractory materials for slagging gasification systems have the potential to reduce costs and improve the overall plant availability by extending the service life. In this study, different refractory materials were evaluated under slagging gasification conditions. Refractory probes were continuously exposed for up to 27 h in an atmospheric, oxygen blown, entrained flow gasifier fired with a mixture of bark and peat powder. Slag infiltration depth and microstructure were studied using SEM EDS. Crystalline phases were identified with powder XRD. Increased levels of Al, originating from refractory materials, were seen in all slags. The fused cast materials were least affected, even though dissolution and slag penetration could still be observed. Thermodynamic equilibrium calculations were done for mixtures of refractory and slag, from which phase assemblages were predicted and viscosities for the liquid parts were estimated.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Gasification, Oxygen blown, Biomass, Entrained flow, Slag, Refractory
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-65625 (URN)10.1016/j.jeurceramsoc.2017.09.016 (DOI)000418211000047 ()2-s2.0-85029532285 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-22 (rokbeg)

Available from: 2017-09-13 Created: 2017-09-13 Last updated: 2018-05-28Bibliographically approved
Ma, C. (2017). Aspects of Ash Transformations in Pressurised Entrained-Flow Gasification of Woody Biomass: Pilot-scale studies. (Doctoral dissertation). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Aspects of Ash Transformations in Pressurised Entrained-Flow Gasification of Woody Biomass: Pilot-scale studies
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pressurised entrained-flow gasification (PEFG) of woody biomass has the potential to produce high purity syngas for the production of vital chemicals, e.g., biofuels. However, ash-related issues such as reactor blockages and refractory corrosion need to be addressed before this potential can be realised from a technical perspective. These undesirable consequences can be brought about by slag formation involving inorganic ash-forming elements and the chemical transformations that they undergo during fuel conversion. The objective of this study was to elucidate the ash transformations of the major ash-forming elements and the slag formation process. A pilot-scale PEFG reactor was used as the basis of the study, gasifying different woody biomass-based fuels including wood, bark, and a bark/peat mixture. Different ash fractions were collected and chemically analysed. Reactor slags had elemental distributions differing from that of the fuel ash, indicating the occurrence of fractionation of ash material during fuel conversion. Fly ash particles from a bark campaign were also heterogeneous with particles exhibiting differing compositions and physical properties; e.g., molten and crystalline formations. Si was consistently enriched in the reactor slags compared to other major ash-forming elements, while analyses of other ash fractions indicated that K was likely volatilised to a significant extent. In terms of slag behaviour, near-wall temperatures of approximately 1050-1200 °C inside the reactor were insufficient to form flowing ash slag for continuous extraction of ash material during firing the woody biomass fuels alone. However, fuel blending of a bark fuel with a silica-rich peat changed the chemical composition of the reactor slags and bulk slag flow behaviour was evident. Thermochemical equilibrium calculations supported the importance of Si in melt formation and in lowering solidus and liquidus temperatures of Ca-rich slag compositions that are typical from clean wood and bark. Viscosity estimations also showed the impact that solids have upon slag flow behaviour and corresponded qualitatively to the experimental observations. Corrosion of reactor refractory was observed. The mullite-based refractory of the reactor formed a slag with the fuel ash slag, which caused the former to flux away. Reactor blockages were also resultant because of the high viscosity of this slag near the outlet.  A preliminary study into the corrosion of different refractories was also carried out, based on firing a bark/peat mixture.  Alumina-rich refractories consisting of corundum, hibonite, mullite, and andalusite tended to form anorthite and exhibited varying degrees of degradation. Infiltration of slag was evident for all the samples and was a severe mode of degradation for some refractories. For fused-cast periclase and spinel-based refractories, slag infiltration was limited to voids and no extensive signs of refractory dissolution were found. This is also supported by a thermochemical equilibrium calculations mimicking slag infiltration that incorporated viscosity estimations. The findings from this thesis contribute towards the development of woody biomass PEFG by highlighting issues concerning ash fractionation, slag behaviours and ash\slash refractory interaction that should be investigated further.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
woody biomass, gasification, ash transformation, slag behaviour, refractory corrosion
National Category
Bioenergy
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62914 (URN)978-91-7583-874-8 (ISBN)978-91-7583-875-5 (ISBN)
Public defence
2017-06-22, E231, Universitetsområdet, Porsön, 97187, Luleå, 10:00 (English)
Supervisors
Funder
Bio4EnergySwedish Energy Agency
Available from: 2017-04-13 Created: 2017-04-06 Last updated: 2017-11-24Bibliographically approved
Ma, C., Carlborg, M., Hedman, H., Wennebro, J., Weiland, F., Wiinikka, H., . . . Öhman, M. (2016). Ash Formation in Pilot-Scale Pressurized Entrained-Flow Gasification of Bark and a Bark/Peat Mixture. Energy & Fuels, 30(12), 10543-10554
Open this publication in new window or tab >>Ash Formation in Pilot-Scale Pressurized Entrained-Flow Gasification of Bark and a Bark/Peat Mixture
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2016 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 12, p. 10543-10554Article in journal (Refereed) Published
Abstract [en]

Pressurized entrained-flow gasification (PEFG) of bark and a bark/peat mixture (BPM) was carried out in a pilot-scale reactor (600 kWth, 7 bar(a)) with the objective of studying ash transformations and behaviors. The bark fuel produced a sintered but nonflowing reactor slag, while the BPM fuel produced a flowing reactor slag. Si was enriched within these slags compared to their original fuel ash compositions, especially in the bark campaign, which indicated extensive ash matter fractionation. Thermodynamically, the Si contents largely accounted for the differences in the predicted solidus/liquidus temperatures and melt formations of the reactor slags. Suspension flow viscosity estimations were in qualitative agreement with observations and highlighted potential difficulties in controlling slag flow. Quench solids from the bark campaign were mainly composed of heterogeneous particles resembling reactor fly ash particles, while those from the BPM campaign were flowing slags with likely chemical interactions with the wall refractory. Quench effluents and raw syngas particles were dominated by elevated levels of K that, along with other chemical aspects, indicated KOH(g) and/or K(g) were likely formed during PEFG. Overall, the results provide information toward development of woody biomass PEFG and indicate that detailed understanding of the ash matter fractionation behavior is essential.

National Category
Energy Systems Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-61329 (URN)10.1021/acs.energyfuels.6b02222 (DOI)000390072900057 ()2-s2.0-85006511826 (Scopus ID)
Funder
Swedish Energy AgencyBio4Energy
Note

Validerad; 2017; Nivå 2; 2017-01-12 (andbra)

Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2018-07-10Bibliographically approved
Moilanen, A., Lehtinen, J., Kurkela, M., Muhola, M., Tuomi, S., Carlsson, P., . . . Backman, R. (2015). Biomass gasification fundamentals to support the development of BTL in forest industry (ed.). Paper presented at . Espoo: Technical Research Centre of Finland (VTT)
Open this publication in new window or tab >>Biomass gasification fundamentals to support the development of BTL in forest industry
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2015 (English)Report (Other academic)
Place, publisher, year, edition, pages
Espoo: Technical Research Centre of Finland (VTT), 2015. p. 201
Series
V T T Technology, ISSN 2242-1211 ; 210
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-23699 (URN)10.13140/2.1.3506.2560 (DOI)80ed3fdc-ffaa-417a-919c-3a55eb64ec0b (Local ID)978-951-38-8220-4 (ISBN)80ed3fdc-ffaa-417a-919c-3a55eb64ec0b (Archive number)80ed3fdc-ffaa-417a-919c-3a55eb64ec0b (OAI)
Note

Godkänd; 2015; 20150225 (joakim)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-28Bibliographically approved
Ma, C., Backman, R. & Öhman, M. (2015). Thermochemical equilibrium study of slag formation during pressurized entrained-flow gasification of woody biomass (ed.). Paper presented at . Energy & Fuels, 29(7), 4399-4406
Open this publication in new window or tab >>Thermochemical equilibrium study of slag formation during pressurized entrained-flow gasification of woody biomass
2015 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 7, p. 4399-4406Article in journal (Refereed) Published
Abstract [en]

The potential slag formation behavior during pressurized entrained-flow gasification (PEFG) of woody biomass has been studied from a thermodynamic perspective with respect to compositional, temperature, and pressure variations. An ash transformation scheme was proposed on the basis of the melt formation potential that arises when gaseous K species are present with Si and Ca. Databases and models in FactSage 6.4 were used to carry out thermochemical equilibrium calculations within ChemSheet. It was found that increasing pressure and increasing Si content expanded the range of operating conditions that are conducive of melt formation, while increasing temperature and increasing Ca content diminished the range. The results from the calculations compared qualitatively well to experimental results and provide further information needed in the development of PEFG reactors for woody biomass

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-9129 (URN)10.1021/acs.energyfuels.5b00889 (DOI)000360026900044 ()2-s2.0-84937119010 (Scopus ID)7b0a4616-f50d-4b0f-8950-ea8a563e4c2a (Local ID)7b0a4616-f50d-4b0f-8950-ea8a563e4c2a (Archive number)7b0a4616-f50d-4b0f-8950-ea8a563e4c2a (OAI)
Note
Validerad; 2015; Nivå 2; 20150608 (ohmmar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Carlsson, P., Ma, C., Molinder, R., Weiland, F., Wiinikka, H., Öhman, M. & Öhrman, O. (2014). Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood (ed.). Energy & Fuels, 28(11), 6941-6952, Article ID 28.
Open this publication in new window or tab >>Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood
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2014 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 11, p. 6941-6952, article id 28Article in journal (Refereed) Published
Abstract [en]

Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-5903 (URN)10.1021/ef501496q (DOI)000345469300029 ()2-s2.0-84949115896 (Scopus ID)416eac11-fef3-4795-9326-e1446632f4a9 (Local ID)416eac11-fef3-4795-9326-e1446632f4a9 (Archive number)416eac11-fef3-4795-9326-e1446632f4a9 (OAI)
Note

Validerad; 2014; 20141018 (ohmmar)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-10-10Bibliographically approved
Ma, C. (2014). Slag Formation During Pilot-Scale Pressurised Entrained-Flow Gasification of Woody Biomass (ed.). (Licentiate dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Slag Formation During Pilot-Scale Pressurised Entrained-Flow Gasification of Woody Biomass
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Pressurised entrained‐flow gasification (PEFG) of sustainable woody biomass offers the opportunity for envi-ronmentally benign production of syngas that is suitable for synthesis of fuels and other chemicals. During the PEFG process, ash-forming matter in the fuel undergoes transformations. Slag formation is an important form of ash transformation that occurs inside a PEFG reactor. In most industrial-scale PEFG of coal, the ash-forming matter becomes predominately molten and flows down the side of the reactor wall to be continuously tapped and removed. The slagging behaviour of woody biomass fuels during PEFG is expected to be different to that of coal, due to significant differences in the amount, composition and reactivity of the ash-forming matter. The objective of this thesis study was to initiate the elucidation of slag formation during PEFG of woody biomass. This was carried out by obtaining and characterising ash deposits and slags from pilot-scale experimental cam-paigns. An oxygen-fired pilot-scale reactor (ETC Piteå, Sweden) was used for the study. A low reactor temperature (< 1200 °C) study was carried out with three different fuels fired in separate experimental campaigns: stem wood, bark and pulp mill debarking residue (PMDR). Deposits were taken from each of the campaigns from the reactor for chemical characterisation. The stem wood fuel resulted in very little deposit that exhibited only minor amounts of melt, or slag, formation with enrichment of Si. The bark and PMDR fuels resulted in larger amounts of deposits with greater amounts of melt formation that were also enriched in Si. It was found that silica-based fuel contaminants, e.g., quartz sand and feldspars, may have an important role in melt formation. Following on, high reactor temperature (> 1350 °C) experimental campaigns involving stem wood produced flowing slags that eventuated in blockages of the reactor outlet. These slags were also retrieved from the reactor and characterised. It was found that they likely comprised of products resulting from detrimental interactions between the fuel ash and the mullite-based refractory used for the reactor wall lining. Viscosity models and thermochemical equilibrium calculations (TECs) were utilised to offer an explanation for the behaviour of the slags. Additional TECs were carried out to investigate the propensity for melt formation between the main ash-forming elements of woody biomass, Ca, K and Si, under global reactor conditions with relevance to PEFG. The results showed that, in general, the conditions for melt formation are broadened with increasing pressure, increasing amounts of Si and increased concentrations of gaseous K species. Dissolution of Al₂O₃ from mullite (Al₆Si₂O₁₃) refractory due to ash deposits and the gasification atmosphere was also predicted by the calculations. A scheme of slag formation during PEFG of woody biomass in a reactor with mullite-based refractory lining was proposed in light of the experimental observations. Some practical suggestions to avoid ash-related problems during PEFG of woody biomass are also discussed. This work forms part of a broader study to elucidate the ash transformations that occur during PEFG of woody biomass, which is necessary in order to develop the process into commercial availability.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2014
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-18723 (URN)a034b9da-8ee0-42a7-984e-b48a4a1532fb (Local ID)978-91-7583-131-2 (ISBN)978-91-7583-132-9 (ISBN)a034b9da-8ee0-42a7-984e-b48a4a1532fb (Archive number)a034b9da-8ee0-42a7-984e-b48a4a1532fb (OAI)
Note
Godkänd; 2014; 20141102 (chamaf); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Charlie Ma Ämne: Energiteknik/Energy Engineering Uppsats: Slag Formation During Pilot-Scale Pressurised Entrained-Flow Gasification of Woody Biomass Examinator: Professor Marcus Öhman, Institutionen för teknikvetenskap och matematik, Luleå Tekniska universitet Diskutant: Universitetslektor Christoffer Boman, Umeå Universitet Tid: Fredag den 12 december 2014 kl 10.00 Plats: E246, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-28Bibliographically approved
Ma, C., Carlborg, M., Backman, R. & Öhman, M. (2014). Slag Formation during Pressurized Entrained-flow Gasification of Woody Biomass: A Thermochemical Equilibrium Study (ed.). Paper presented at Impacts of Fuel Quality on Power Production : 26/10/2014 - 31/10/2014. Paper presented at Impacts of Fuel Quality on Power Production : 26/10/2014 - 31/10/2014.
Open this publication in new window or tab >>Slag Formation during Pressurized Entrained-flow Gasification of Woody Biomass: A Thermochemical Equilibrium Study
2014 (English)Conference paper, Oral presentation only (Refereed)
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-40464 (URN)f9c47a05-14f1-4306-b056-d1214921731a (Local ID)f9c47a05-14f1-4306-b056-d1214921731a (Archive number)f9c47a05-14f1-4306-b056-d1214921731a (OAI)
Conference
Impacts of Fuel Quality on Power Production : 26/10/2014 - 31/10/2014
Note
Godkänd; 2014; 20141108 (ohmmar)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-05-28Bibliographically approved
Ma, C., Weiland, F., Hedman, H., Boström, D., Backman, R. & Öhman, M. (2013). Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass (ed.). Energy & Fuels, 27(11), 6801-6814
Open this publication in new window or tab >>Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass
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2013 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 11, p. 6801-6814Article in journal (Refereed) Published
Abstract [en]

Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-10673 (URN)10.1021/ef401591a (DOI)000327557800050 ()2-s2.0-84888316296 (Scopus ID)982a3b0c-097e-4365-9414-f0d9d9b801bd (Local ID)982a3b0c-097e-4365-9414-f0d9d9b801bd (Archive number)982a3b0c-097e-4365-9414-f0d9d9b801bd (OAI)
Note

Validerad; 2013; 20131104 (ohmmar)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-10-10Bibliographically approved
Ma, C., Weiland, F., Boström, D., Backman, R. & Öhman, M. (2012). Ash formation during pilot-scale trials of pressurized entrained-flow gasification of woody biomass (ed.). Paper presented at Impacts of Fuel Quality on Power Production and the Environment : 23/09/2012 - 27/09/2012. Paper presented at Impacts of Fuel Quality on Power Production and the Environment : 23/09/2012 - 27/09/2012.
Open this publication in new window or tab >>Ash formation during pilot-scale trials of pressurized entrained-flow gasification of woody biomass
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2012 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Deposits, ash samples and residues from pressurised entrained-flow gasification (PEFG) of stem wood, bark and rejected pulpwood have been characterised with SEM-EDS during trials in an O2-blown pilot-scale reactor. Global thermochemical equilibrium calculations based on the conditions inside the hot reactor were carried out to investigate the phase distribution of potassium as both a function of temperature and Si reactivity. Substantial deposit formations on the reactor probe were only evident in the trials with the woody fuels containing a higher ash content; i.e., experiments with pulpwood and bark. Of these, the deposits formed during gasification of the pulpwood fuel, likely to have been relatively highly contaminated, showed more hard and sintered material. The deposits/slag formed contained typical sand particles (e.g. quartz and feldspars) embedded in a silicate rich melt. The melt in the slag is dominated by silicon 40-55 mol%, aluminium ~15 mol% and calcium 10-20 mol%, with a further ~10 mol% consisting of alkali metals sodium and potassium. The preliminary results suggest that fuel contaminants (e.g., quartz and feldspars) may play a significant role in the slag formation process in entrained flow gasification of woody biomass fuels and that a significant share of the potassium is leaving the hot reactor as gaseous alkali species.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-28717 (URN)29c86e4a-807e-4687-83ed-84c2bf145955 (Local ID)29c86e4a-807e-4687-83ed-84c2bf145955 (Archive number)29c86e4a-807e-4687-83ed-84c2bf145955 (OAI)
Conference
Impacts of Fuel Quality on Power Production and the Environment : 23/09/2012 - 27/09/2012
Note
Godkänd; 2012; 20121002 (ohmmar)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0555-5924

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