Search

Godkänd; 2015; 20150225 (joakim)

Godkänd; 2015; 20151101 (ohmmar)

Godkänd; 2015; 20151101 (ohmmar)

Godkänd; 2014; 20140831 (ohmmar)

Godkänd; 2014; 20150221 (ohmmar)

Godkänd; 2014; 20141108 (ohmmar)

Gasification of biomass in the entrained flow process requires temperatures above 1000°C and pressures above 20 bar. Together with the ash forming elements, a harsh environment is created inside these reactors and degradation of construction material is likely to occur. This will lead to unplanned stops and increased maintenance work resulting in economic loss. In this work, two refractory materials (63 and 83 weight percent alumina) were exposed to synthetic ash composed of K2CO3, CaCO3 and SiO2 to study chemical attack on and interactions with the refractory materials. The exposure went on for 7 days in 1050°C and CO2­atmosphere in a muffle furnace. It was found that potassium (K) is the most active element in attack of the refractories and is transported fastest in the material. A melt composed of K, Ca and Si was formed that prevented penetration of K but it also dissolved aluminum from the refractory materials. X­ray diffraction showed that the crystalline phases leucite, kalsilite, kaliophilite, K(2­x)Al(2­x) SixO4 and wollastonite had formed. Formations of new phases in refractories will cause stress and eventually failure within refractories., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 446-449

Godkänd; 2013; 20130817 (ohmmar)

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. Godkänd; 2012; 20121002 (ohmmar)

Godkänd; 2012; 20121223 (ohmmar)

Godkänd; 2012; 20121216 (ohmmar)

Godkänd; 2012; 20120707 (ohmmar)

Godkänd; 2012; 20121216 (ohmmar)

Godkänd; 2011; 20111020 (ohmmar)

The heating sector (0.05 to 20 MW) is during the coming years facing an increased competition for (bio) fuels and, at the same time, an expanded broadening of the raw material base for fuels. At the same time the demand for availability, efficiency and environmental performance are increasing. This report describes key barriers, knowledge gaps and needs for research, development and demonstration activities identified. Producers of fuels and of combustion equipments as well as users have been identified and their views have been collected through interviews and / or questionnaires. Research and ongoing programs and activities in Sweden are described briefly. The results show great need for knowledge of new fuels in the whole chain from fuel processing to quality assurance, combustion and emission reduction. There is also great need for coordination of resources, clarification of the research structure, increased contact and improved communication and implementation of results. Based on the results a structure, content and funding of a coordinated R & D program with a focus on the heating sector 0,05-20 MW is proposed. Key factors for success are the inclusion of the entire chain fuel-conversion-system/environment, coordination of physical locations for research and development, and overall governance. All three parts basic research, applied research and demonstration should be included. Närvärmesektorn (0,05-20 MW) står de kommande åren inför ökad konkurrens om, och en utvidgad råvarubas för (bio)bränslen. Samtidigt ökar kraven på tillgänglighet, effektivitet och miljöprestanda. Denna rapport beskriver viktiga hinder, kunskapsbrister och behov av forsknings-, utvecklings- och demonstrationsinsatser identifierade hos bränsle- och utrustningstillverkare samt användare inom sektorn. Aktörer har kartlagts och deras synpunkter har samlats in via intervjuer och/eller enkäter. Forskningsmiljöer och pågående program och aktiviteter i Sverige beskrivs kortfattat. Resultaten visar på stora behov av kunskap kring nya bränslen i hela kedjan från bränsleförädling till kvalitetssäkring, förbränning och emissionsreducering. Det finns även stort behov av samordning av resurser, tydliggörande av forskningsstruktur, ökad kontaktyta och förbättrad kommunikation och implementering av resultat. Baserat på resultaten föreslås struktur, innehåll och finansiering av ett samordnat FUD-program med fokus Närvärme. Viktiga framgångsfaktorer är inkludering av hela kedjan bränsle-omvandling-system/miljö, samodning av fysiska lokaliseringar för forskning och utveckling och övergripande styrning. Alla tre delmomenten grundforskning, tillämpad FoU och demonstration bör ingå. Godkänd; 2011; 20110711 (ohmmar)

In the presented work the range of variation for particular fuel properties is shown for different types of solid biomass, and the relevance of these properties with regard to ash melting behavior is investigated. Fuels are classified based on elemental composition and ash content, and resulting groups are compared to type and origin of the raw material basis and ash melting properties. Selected indices and equations for an assessment of the ash melting properties are applied to own biomass data, and evaluation is done by comparing the resulting fuel assessment or predicted values to characteristic ash melting temperatures measured in laboratory tests according to DIN 51730 and SS-ISO 540., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1283-1286

Godkänd; 2011; 20111204 (ohmmar)

Torvbränslen används ofta i kombination med trädbränslen i värme- och kraftvärmeverk. Den kombinationen har visat sig ge förbränningstekniska fördelar kanske främst minskad risk för askrelaterade driftsproblem. Erfarenheter saknas dock vad gäller eventuella positiva sameldningseffekter/erfoderliga inblandningsgrader av torv i många kommande åkerbränslen såsom salix, rörflen och halm. Projektets mål har därför varit att: i) bestämma vilka typiska inblandningsgrader av torv i olika åkerbränslen (halm, salix och rörflen) som krävs för att uppnå positiva effekter m a p slaggning, beläggningsbildning/(högtemperaturkorrosion) och bäddagglomerering, samt ii) demonstrera möjligheterna att minska uppkomsten av askrelaterade driftsproblem i förbränningsanläggningar genom inblandning av torv till intressanta åkerbränslen. Termokemiska modellberäkningar utfördes för att bestämma effekter av torvinblandning till halm, salix och rörflen med hög och låg askhalt på reduktionen av slaggnings-, beläggningsbildnings-/(korrosion)- och bäddagglomereringsrisken vid förbränning. Dessa resultat och tidigare utförda försök i bänkskala låg sedan till grund för valda bränslekombinationer, torvinblandningsgrader och torvprov i de sedan utförda demonstrationsförsöken. Dessa demonstrationsförsök utfördes i en rosteranläggning på 4 MW (rörflen/rörflensmixar och salix/salixmixar) och i en pelletsbrännare/-panna i bänkskala (20 kW) (halm/halmmixar). Resultaten visar att inblandning av typisk starrbaserad bränntorv i salix och rörflen med låg askhalt ger positiva effekter vad avser bäddagglomerering och beläggningsbildning/(korrosion) i pannors konvektionsdelar redan vid relativt låga inblandningsgrader (15 vikts-% på TS basis). En starrbaserad bränntorv med relativt högt Ca/Si förhållande bör väljas för sameldning med salix i rosteranläggningar för att inte öka slaggningsrisken. Samma torvtyp kan också i rosteranläggningar nyttjas i sameldning med rörflen med låg askhalt (relativt låga inblandningsgrader räcker d v s 15 vikts-% på TS basis) och vetehalm (höga inblandningsgrader krävs d v s upp mot 40 vikts-% på TS basis) för att reducera slaggningsrisken. Vid val av torvslag för att maximera de ovanstående positiva effekterna vid förbränning kan därför en allmän rekommendation göras att torvar med hög askhalt (starrinnehållande torv), och gärna med högt inslag av svavel, ger de bästa sameldningsegenskaperna med det tilläget att vid rostereldning bör en torv med relativt högt Ca/Si förhållande väljas (gärna upp mot 1 på vikts-% basis). Rörflen med hög askhalt förväntas inte ge upphov till några större problem med beläggnings- och slaggnings-/bäddagglomereringsproblem och är därför i första hand inte intressant att samelda med torv utifrån ett askrelaterat driftsproblemperspektiv. För att reducera beläggningstendensen till låga nivåer vid sameldning med vetehalm krävs troligen så höga nivåer att detta inte är praktiskt intressant. Godkänd; 2010; 20100701 (ohmmar)

Resultaten visar att energigräset rörflen kan utgöra ett kompletterande bränsle till det skogsbränsle och den torv som idag används i svenska värme- och kraftvärmeanläggningar. En inblandning av rörflen med ca 10 % på energibasis i en bränslemix som för övrigt består av 10-20 % carextorv och 70-80 % träbränsle har i demonstrationsförsök visat goda resultat. Denna bränslemix har vid fullskaliga förbränningsförsök i fluidiserande bädd (Hedensbyn,CFB 98 MW) under sammanlagt 4 dygn inte gett upphov till störningar eller negativa effekter på utrustning eller ökade utsläpp i rökgaserna i form av partiklar eller gasformiga emissioner. Vid simulerade påverkan på överhettare i form av kylda sonder har även konstaterats att beläggningstillväxten varit oförändrad och ej givit upphov till ökad korrosion. Inblandning i bränslemixen har skett med hackad rörflen (40-50 mm) i torvdelen för att en jämn inblandning kunde åstadkommas. Rörflensmaterialet har levererats i samband med skörden så att det hackats direkt på fältet med exakthack kopplad till vagn eller med containerhantering. Vid leverans under vår och försommar har rörflenen hållit mycket låg fukthalt med ett medel på 11,3 % fukt. Jämförande studier har gjorts med system där rörflen vid skörden under vår pressats till storbalar för vidare transport till terminal eller gårdscentrum. Detta system har visat sig mindre effektivt jämfört med direkthackning på fältet och transport av hackat material till värmeverk. En fördel med storbalssystemet är dock att det möjliggör mer kostnadseffektiv lagring utan att t.ex. fukthalten höjs under lagringstiden. Även vägtransport från terminal eller gårdscentrum till värmeverk har visat sig mer effektivt med storbalar jämfört med hackat material. Vid lastning av stora fyrkantsbalar (90x120x220 cm) på lastbil med släp uppnåddes i stort sett dubbla lastvikten jämfört med hackad rörflen (20,9 ton jmf. m. 11,0 ton). För de något mindre anläggningarna av typen rosterpannor som provats (0,6 och 4 MW) har den briketterade formen av rörflen använts för att uppnå en jämn och koncentrerad bränslematning. Även här har en blandning av rörflen och torv visat sig användbar och speciellt för rörflen med låg askhalt har torvinblandning på 15 vikts-% av gett minskad tendens till sintring av askan. Rörflen med hög askhalt (utan torvinblandning) har kunnat sameldas med träbränsle utan risk för sintrad aska i dessa anläggningar. Tillverkningen av briketter för försöken, sammanlagt ca 35 ton, varav hälften med inblandning av torv har genomförts utan störningar och med bra kvalité på briketterna. Godkänd; 2010; 20100701 (ysko)

Resultaten från försöken visar att fosforrika additiv kan vara intressanta för att reducera beläggningsbildning och högtemperaturkorrosion utan att i någon större omfattning öka slaggnings- och bäddagglomereringstendensen hos typiska biobränslen. För att erhålla en märkbar positiv effekt av kaliumbindning till fosfater krävs att mängden kalcium och magnesium i den slutgiltiga bränslemixen inte är alltför hög relativt mängden fosfor, då framför allt Ca men till viss del även Mg reagerar med P innan K binds in effektivt. Generellt behövs troligen inblandningsgrader motsvarande en molkvot P/(K+Na+2/3Mg+2/3Ca) i bränslemixen som närmar sig 1. För att erhålla en molkvot på 1 i ett typiskt halm-, salix- eller grotbränsle innebär det i praktiken en fosfortillsats motsvarande 12, 4.7 respektive 3.7 gram rent P per kg torrt bränsle. Godkänd; 2010; 20101114 (ohmmar)

Slag and ash deposition problems have more than occasionally been observed in biomass fueled plants in general and especially in pellet fired plants. These problems could lead to reduced accessibility as well as performance of the combustion appliances. Slag formation including measures for prevention and prediction during combustion of biomass fuels has been studied by the research groups at Luleå University of Technology, Umeå University, Energy Technology Center and Swedish University of Agricultural Sciences for about one decade know. Several (about 40) different biomass fuels/fuel mixtures have been studies and many different fuel additives/co-combustion fuels have been used to combat slag formation. About 25 scientific papers and 10 technical reports have been published by the research groups within the topic of slag formation during combustion of biomass fuels. The general experiences and conclusions of our research within the area will be presented. Godkänd; 2009; 20090822 (ohmmar)

Upgraded biofuels as pellets, briquettes and powder are today commonly used in small as well as large scale appliances. In order to cover a great fuel demand new materials as bark, whole tree assortments and peat are introduced. These materials have higher ash content why they are potentially more problematic compared with stem wood. Ash related problems in the combustion device, e.g. fouling, slagging and corrosion may occur from the incombustible leftover i.e. the fuel ash. The objective of the present work was to determine the effect on slagging characteristics when co-pelletizing peat into woody biomass. In this project woody biomass (pine and spruce 50/50) has been co-pelletized with three different mixtures (low, medium and high) of peat; peat A with high ash and high Si content and peat B with low ash and a relatively high Ca/Si content. There were totally 6 mixed assortments in which softwood sawdust and energy wood each represented the biomass in 3 samples respectively. The experiments were carried out in a commercial underfed pellet burner (20 kW) installed in a reference boiler. X-ray diffraction (XRD) was used to characterize the phase composition and scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDS) were utilized in order to characterize the elemental distribution and morphology of the collected slag deposits and bottom ashe. The slagging tendency showed an obvious increment when adding peat into the woody biomasses. Especially the ash- and relatively Ca-poor sawdust fuel was generally more sensitive for the different peat assortments. Co-firing of peat A (high ash- and Si content) resulted in the most severe slagging tendency, where four out of six experiments led to a total shut down of the burner due to the slagging. The slagging tendency was significantly lower when adding peat B (ash poor and relatively high (Ca/Si ratio) into the woody biomass fuels. A significant increment of the Si, Al and Fe content and a significant decrement of the Ca content could be seen when increasing the mixing content of peat A in both woody biomasses. The slag from the peat B mixtures had a slightly higher Ca content compared with the Si content and a clearly higher Ca content compared with the peat A mixtures. When introducing the relatively silicon rich Peat A to the woody biomasses the slagging tendency increased because high temperature melting Ca-Mg oxides reacts to form more low temperature melting Ca-Al-K silicates. In the case of the more ash poor peat B, with relatively high Ca/Si ratio, there were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting Ca-Al-K silicates were formed. Godkänd; 2009; 20091104 (nysida)

There is relatively extensive knowledge available concerning ash transformation reactions during energy conversion of woody biomass. Traditionally, these assortments have constituted the main resources for heating in Sweden. In recent decades the utilization of these energy carriers has increased, from a low technology residential small scale level to industrial scale (i.e. CHP plants). Along this evolution ash‐chemical related phenomena for woody biomass has been observed and studied. So, presently the understanding for these are, if not complete, fairly good. Briefly, from a chemical point of view the ash from woody biomass could be characterized as a silicate dominated systems with varying content of basic oxides and with relatively high degree of volatilization of alkali sulfates and chlorides. Thus, the main ash transformation mechanisms in these systems have been outlined. However, since the demand for CO2‐neutral energy resources has increased the last years and will continue to do so in the foreseeable future, other biomasses as for instance agricultural crops has become highly interesting. Globally, the availability of these shows large variation. In Sweden, for instance, which is a relatively spare populated country with large forests, these bio‐masses will play a secondary role, although not insignificant. In other parts of the world, more densely populated and with a large agricultural sector, such bio‐masses may constitute the main energy bio‐mass resource in the future. However, the content of ash forming matter in agricultural bio‐mass is rather different in comparison to woody biomass. Firstly, the content is much higher; from being about 0.3 – 0.5% (wt) in stem wood, it can amount to between 4 and 10 %(wt) in agricultural biomass. Furthermore, the composition of the ash forming matter is different . Shortly, the main difference is due to a much higher content of phosphorus which has major consequences on the ash‐transformation reactions. In many crops, the concentration of phosphorus and silicon is equivalent, which (depending on the concentration levels of basic oxides) may result in a phosphate dominated ash. The properties of this ash are in several aspects different from the silicate dominated woody biomass ash and will consequently behave differently in various types of energy conversion systems. The knowledge about phosphate dominated ash systems has so far been scarce. We have been working with these systems, both with basic and applied research, for about a decade know. Some general experiences and conclusions as well as some specific examples of our research will be presented. Godkänd; 2009; 20090822 (ohmmar)

Godkänd; 2009; 20090823 (ohmmar)

Godkänd; 2008; 20081013 (ohmmar)

Godkänd; 2008; 20080831 (ohmmar)

Godkänd; 2008; 20080906 (ohmmar)

Godkänd; 2008; 20080627 (ysko)

Godkänd; 2008; 20081013 (ohmmar)

Godkänd; 2008; 20081013 (ohmmar)

Godkänd; 2008; 20080627 (ysko)

When rape oil is chemically extracted, rape seed meal, a solid residue remains. Currently, it is used as animal feed. Several plants for the production of rape methyl ester (RME, biodiesel) are in operation or under construction. Combustion properties have been studied for rape seed meal produced as a by product to rape-methyl esther (RME, biodiesel). Composition of the material has been measured, using proximate and ultimate analysis. The lower heating value was 18.2 ± 0,3 MJ/kg d.w. and the ash content was 7-8 percent d.w. The material is rich in nitrogen and sulphur. Concentrations of K, P, Ca and Mg are high in the fuel. Rape seed meal was mixed with bark and pelletised. Bark pellets were also used as a reference fuel. Pellets with 10 and 30 percent rape seed meal were produced. Material with 80 percent rape seed meal and 20 percent planer shavings was also pelletised. Wood had to be added to provide enough friction in the pelletising process, with adapted equipment rape seed meal could probably be easily pelletised). The material was studied using Thermo-Gravimetric Analysis (TGA), and compared with data from tests with wood powder. The pyrolysis of the rape seed meal has a characteristic temperature of 320oC. Devolatilisation starts at 150 oC (at a lower temperature than for wood powder), and proceeds within a rather wide temperature range. The probable cause is the difference in organic content, in particular protein content. The result does not suggest that the material will be difficult to ignite. Experiments in a bench-scale fluidised bed (5 kW) showed that pellets containing only bark, and the mixture rape seed meal/wood had a bed agglomeration temperature well over the normal operational bed temperature. For the fuel mixtures rape seed meal and bark, the agglomeration temperature was slightly over the operational temperature. Particle emissions from fluidised bed combustion and grate combustion were, the latter simulated using a commercial pellet burner, were roughly doubled with fuels containing rape seed meal compared to bark. In the powder burner tests, particle emissions increased with a factor 17 with rape seed meal compared to wood powder. The emitted particles were mainly found in the fine (< 1 µm) mode during grate and powder combustion. During fluidized bed combustion the total particulate matter consisted both of a coarse (>1 µm) and a fine mode fraction. The particles from grate combustion of bark contain mostly K, S, Na and Cl apart from oxygen and carbon. When rape seed meal is present, Cl and Na concentrations decrease considerably and the main contents of the particles are K and S (and O and C). The results from the X-ray Diffraction Spectroscopy (XRD) analyses showed the presence of crystalline K2SO4 och KCl. The fine particles (

Projektet har visat att det är mycket svårt att få tunn aluminiumfolie, som normalt finns i bl.a. hushållsavfall, att oxidera oberoende av tid, temperatur och förbränningsatmosfärens sammansättning. Vidare har svävhastighetsmätningar visat att tunn plastbelagd aluminiumfolie lätt kan ryckas med rökgaserna vid normala rökgashastigheter (1-5 m/s). Godkänd; 2007; 20070816 (ysko)

In the present work, several agricultural biomass fuels, namely straw, Miscanthus,maize whole crop and horse manure mixed with two bedding materials, woodshavings and straw, were reviewed in terms of fuel characteristics. Furthermore,these fuels were tested in several existing boiler technologies and the particulateand gaseous emissions were monitored. The ash was analysed visually in terms ofpresence of sintered material. As expected, all the fuels showed problems withash lumping and slag formation, especially straw and horse manure. Differentboiler technologies showed different operational performance regarding ash andslag management. Miscanthus was the best fuel tested regarding emissions. Maizeand horse manure are problematic fuels regarding NOx and particulate emissions.Due to the big variation of the fuel properties and therefore combustion behaviourof agricultural biomass, further R&D is required to adapt the existing small-scalecombustion systems for these new fuels. Improvements in the combustionchamber design, controlling technology and ash removal systems of small-scalecombustion systems are therefore essential. Godkänd; 2007; Bibliografisk uppgift: CD; 20071204 (joakim)

Godkänd; 2007; 20080101 (ohmmar)

Godkänd; 2001; Bibliografisk uppgift: Sider: 1-3; 20080107 (ohmmar)