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Co-combustion of Animal Waste, Peat, Waste Wood, Forest Residues, and Industrial Sludge in a 50 MWth Circulating Fluidized-Bed Boiler: Ash Transformation, Ash/Deposit Characteristics, and Boiler Failures
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. (Thermochemical Energy Conversion Laboratory)
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. (Thermochemical Energy Conversion Laboratory)
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. (Thermochemical Energy Conversion Laboratory)
2013 (engelsk)Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 10, s. 5617-5627Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In strive to lower the energy conversion cost and CO2 net emission, more complex biofuels are used. The combustion of these fuels often creates aggressive and problematic fireside environments in boilers, resulting in reduced availability, which, in turn, may lead to increased usage of fossil fuel in backup boilers. The objective of the present work was to contribute to the efforts of maximizing the availability of a 50 MWth circulating fluidized-bed (CFB) boiler firing complex fuels with high amounts of P, Ca, S, Cl, N, K, and Na. In the present work, ash and deposit samples collected from the flue gas system of a CFB boiler were further analyzed with X-ray powder diffraction, complementing earlier analysis made on the same sample set with scanning electron microscopy equipped with energy-dispersive spectrometry. Thermodynamic calculations were also made. The results clarify details about the ash speciation and transformation as well as effects on boiler operation. A suggestion of a control strategy to minimize corrosion rates in superheaters and SO2 emission to downstream cleaning equipment in full-scale industrial boilers is made. An equation for rough estimation of fuel mix corrosion tendencies is also presented.

sted, utgiver, år, opplag, sider
American Chemical Society (ACS), 2013. Vol. 27, nr 10, s. 5617-5627
HSV kategori
Identifikatorer
URN: urn:nbn:se:umu:diva-83910DOI: 10.1021/ef400542hISI: 000326126700004OAI: oai:DiVA.org:umu-83910DiVA, id: diva2:678122
Forskningsfinansiär
Bio4EnergyTilgjengelig fra: 2013-12-11 Laget: 2013-12-10 Sist oppdatert: 2018-06-08bibliografisk kontrollert
Inngår i avhandling
1. Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler: ash transformation, availability and process improvements
Åpne denne publikasjonen i ny fane eller vindu >>Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler: ash transformation, availability and process improvements
2014 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The direct variable costs for heat and electricity production based on solid biomass fuel combustion is approximately 3-5 times lower than the costs in a fossil fuel-oil based boiler in Sweden. In addition waste derived biomass fuels are typically much cheaper than biomass not classified as waste. The introduction of the waste derived fuels; wastewater treatment sludge, demolition wood, and animal waste in a 50MWth circulating fluidized bed (CFB) biomass boiler located in Perstorp, Sweden, led to rapid deposit buildup in superheaters, heavy ash accumulation in economizers and failing boiler tubes and vortex finders that forced frequent boiler shutdowns. This in turn increased the use of expensive oil (fossil fuel) in backup boilers and the CO2 footprint of the on-site energy conversion system. This work aims to increase the general mechanistic understanding of combustion systems using complex fuels, and includes: A mapping of the boiler failure and preventive maintenance statistics; elemental composition analysis of ash, deposits and fuel fractions; flue-gas composition measurements; chemical speciation analysis; an attempt to describe the overall ash transformation reactions and mass balance throughout the combustion process. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used to analyze the elemental composition of ash and deposits. The SEM-EDS results were used together with data from X-ray powder diffraction (XRD) analysis, thermodynamic phase data, and equilibrium calculations in an attempt to quantify the crystalline phases and the overall ash transformation of the process. Based on the findings concerning ash transformation and the failure statistics, it has been possible to identify generic key parameters regarding boiler design and process parameters, enabling major improvements of the CFB boiler availability, a lower overall energy conversion cost and a reduced CO2 footprint.

Abstract [sv]

Den direkta rörliga kostnaden för värme-och elproduktion baserad på fast biobränsle är ungefär 3-5 gånger lägre än kostnaden för fossiloljebaserad produktion. Avfallsklassade fasta biobränslen är vidare oftast betydligt billigare än fasta biobränslen som inte är klassade som avfall. Införandet av de avfallsklassade bränslena; reningsslam, rivningsvirke, och animaliskt avfall i en 50MWth cirkulerande fluidiserad bädd (CFB) -panna, ledde till kraftig beläggningstillväxt i överhettare och ackumulering av aska i ekonomisers, samt haveri av panntuber och centrumrör i cyklonerna, som tvingade fram frekventa pannstopp. Detta ökade i sin tur användningen aveldningsolja (fossilt bränsle) i reservkrafts-pannor vilket resulterade i ett större CO2 utsläpp och en högre kostnad för energiomvandlingen på siten. Detta arbete syftar till att öka den allmänna mekanistiska förståelsen av förbränningssystem som använder komplexa bränslen, och omfattar; haveri- och underhållsstatistik, elementarsammansättningsanalys av aska, beläggningar och bränslefraktioner, rökgasens sammansättning, kemisk specificering av askor och beläggningar, ett försök att beskriva de övergripande askomvandlingsreaktionerna, samt en massbalans för förbränningsprocessen. Svepelektronmikroskop (SEM) utrustat med energidispersiv röntgenspektroskopi (EDS) användes för att analysera den elementära sammansättningen av aska och beläggningar. SEM-EDS-resultaten användes tillsammans med pulverröntgendiffraktionsanalys (XRD), termodynamiska fasdata, och jämviktsberäkningar i ett försök att kvantifiera de kristallina faserna och de övergripande askomvandlingsreaktionerna i processen. Baserat på resultaten rörande askomvandling och haveristatistik, har det varit möjligt att identifiera generiska nyckelparametrar gällande panndesign och processparametrar, som möjliggjort stora förbättringar av CFB pannans tillgänglighet, en lägre totalkostnad för energiomvandlingen på siten samt ett minskat CO2-utsläpp.

sted, utgiver, år, opplag, sider
Umeå: Umeå universitet, 2014. s. 60
Emneord
Co-combustion, animal waste, peat, waste wood, forest residues, industrial sludge, limestone, CFB boiler, ash transformation, corrosion, erosion, ash and deposit characteristics, deposit buildup, boiler failures, availability, sulfation, boiler design, boiler conversion, waste derived fuels, large scale, Samförbränning, animaliskt avfall, torv, returträ, skogsbränsle, reningsslam, askomvandling, korrotion, erosion, ask- och beläggnings-karaktäristik, beläggningstillväxt, tillgänglighet, sulfatisering, panndesign, pannkonvertering, avfallsderiverade bränslen, storskalig
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-114736 (URN)978-91-7601-060-0 (ISBN)
Presentation
2014-06-10, Naturvetarhuset, N300, Umeå universitet, Umeå, 13:00 (engelsk)
Veileder
Forskningsfinansiär
Bio4Energy
Tilgjengelig fra: 2016-01-28 Laget: 2016-01-27 Sist oppdatert: 2018-06-07bibliografisk kontrollert
2. Co-firing complex biomass in a CFB boiler: ash transformation, corrosion control and materials selection
Åpne denne publikasjonen i ny fane eller vindu >>Co-firing complex biomass in a CFB boiler: ash transformation, corrosion control and materials selection
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Alternativ tittel[sv]
Samförbränning av komplex biomassa i en CFB-panna : askomvandling, korrosion och materialval
Abstract [en]

The effects of greenhouse gas net emissions on global warming, stricter legislation on waste handling, and the pursuit of ever cheaper heat- and power production are all important factors driving the introduction of complex fuels in incineration plants. However - without fundamental knowledge regarding ash transformation, corrosion control, and materials selection – this introduction of potentially economically and environmentally beneficial fuels, might instead cause economic loss and environmentally adverse effects.

The present work is a contribution to the transition from today's CO2 net generating energy conversion system, to a more environmentally friendly and cost-efficient one. This is done using scientific methods to generate knowledge concerning mechanisms of ash transformation, corrosion control, and materials selection, in a co-fired industrial scale circulating fluidized bed (CFB) boiler, using a novel and biomass-based fuel mix, rich in Na, K, Cl, N, S, P, Ca and Si. Fuel fractions, ashes, flue gas, deposits, and construction material samples have been collected and analyzed using various techniques, including scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray Diffraction (XRD). The experimental results have been evaluated and interpreted using chemical equilibrium calculations.

The results of this work include:

1) An analysis of; the failure and preventive maintenance statistics of the industrial scale CFB boiler at hand; the elemental composition of boiler ashes and deposits, the flue gas composition and elemental composition of a multitude of fuel fractions; correlations between boiler design, operational parameters, elemental composition of deposits and boiler availability; a boiler elemental mass balance revealing details regarding deposit buildup mechanisms; properties of the fly ash relevant to flue gas filter design; and findings regarding the nitrogen chemistry of the novel and nitrogen-rich fuel mix.

2) Speciation and description of the overall ash transformation and fireside alloy interaction, enabling the implementation of on-line corrosion control which significantly inhibits superheater and dew-point corrosion in the boiler; and, an equation describing the sulfation potential of the fuel mix, as a result of the direct and indirect interactions between all major ash-forming elements.

3) A literature review relevant for the co-fired CFB cyclone vortex finder alloy selection and corrosion at 880 °C; An alloy selection study including long term exposures of several commercially available alloys identifying materials that are more than twice as cost-efficient as the often used alloy 253MA; a suggestion of novel methods for both systematic comparison of heavily degraded alloys, and for alloy service-life estimations; a detailed analysis of heavily degraded alloys 310S, 800H/HT and 600, identifying the driving corrosion mechanisms of the VF alloy degradation, including aspects of how the alloy internal mass transport and fireside surface interaction develops over time.

The knowledge gained during this project has been used in the improvement work of the Perstorp 50 MWth CFB boiler, improving the boiler availability with 7 %, reducing the overall energy conversion costs with around 1.7 MEUR/year.

sted, utgiver, år, opplag, sider
Umeå: Umeå University, 2018. s. 106
Emneord
ash transformation, process control, equilibrium calculations, boiler availability, failures, alloy selection, alloy degradation, vortex finder (VF), service life estimation, sulfation, chloridation, high temperature corrosion, biomass, waste derived fuels, forest residues, RDF, Biomal, slaughterhouse waste, peat, waste wood, industrial waste water treatment sludge, HAD, RSMT, Alloy 253MA, Alloy 310S, Alloy 800H/HT, Alloy DS, Alloy 600
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-145106 (URN)978-91-7601-855-2 (ISBN)
Disputas
2018-03-16, N460, Naturvetarhuset, Umeå Universitet, Umeå, 13:00 (svensk)
Opponent
Veileder
Forskningsfinansiär
Bio4EnergySwedish Research Council
Tilgjengelig fra: 2018-02-23 Laget: 2018-02-21 Sist oppdatert: 2018-06-09bibliografisk kontrollert

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