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| 4. |
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| 5. |
- Boman, Christoffer, et al.
(författare)
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Evaluation of a constant volume sampling setup for residential biomass fired appliances : Influence of dilution conditions on particulate and PAH emissions
- 2005
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 29:4, s. 258-268
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Tidskriftsartikel (refereegranskat)abstract
- Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residential biomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constant volume sampling (CVS) is an alternative method but different sampling conditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residential biomass fired appliances and determine the influence of dilution sampling conditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3-7x), sampling temperature (45-75°C), dilution tunnel residence time (2-4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The sampling conditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5°C and 3-4 times dilution as robust and applicable conditions in the presently designed setup. © 2005 Elsevier Ltd. All rights reserved.
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| 9. |
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| 10. |
- Boman, Christoffer, et al.
(författare)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 1: Pellet stoves
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 307-314
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Tidskriftsartikel (refereegranskat)abstract
- Stove performance, characteristics and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter and chimney draught. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene and benzene and the emissions of VOC varied in the range 1.1-47 mg/MJfuel. PAH emissions (2-340 µg/MJfuel) were generally dominated by phenantrene, fluoranthene and pyrene. PMtot (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm and number concentrations in the range 4×1013- 3×1014 particles/MJfuel. During high load conditions the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur and chlorine, in the form of K2SO4, K3Na(SO4)2 and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.
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| 11. |
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| 12. |
- Carlsson, Per, et al.
(författare)
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Experimental investigation of an industrial scale black liquor gasifier : 1. Influence of reactor operation parameters on product gas composition
- 2010
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 89:12, s. 4025-4034
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Tidskriftsartikel (refereegranskat)abstract
- A novel technology to mitigate the climate changes and improve energy security is Pressurized Entrained flow High Temperature Black Liquor Gasification (PEHT-BLG) in combination with an efficient fuel synthesis using the resulting syngas. In order to optimise the technology for use in a pulp and paper mill based biorefinery, it is of great importance to understand how the operational parameters of the gasifier affect the product gas composition. The present paper is based on experiments where gas samples were withdrawn from the hot part of a 3 MW entrained flow pressurized black liquor gasifier of semi industrial scale using a high temperature gas sampling system. Specifically, the influence of process conditions on product gas composition (CO2, CO, H2, CH4, H2S, and COS) were examined by systematically varying the operational parameters: system pressure, oxygen to black liquor equivalence ratio, black liquor flow rate to pressure ratio and black liquor pre-heat temperature. Due to the harsh environment inside the gasification reactor, gas sampling is a challenging task. However, for the purpose of the current study, a specially designed high temperature gas sampling system was successfully developed and used. The results, obtained from two separate experimental campaigns, show that all of the investigated operational parameters have a significant influence on the product gas composition and present valuable information about to the process characteristics.
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| 13. |
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| 14. |
- Dahlman-Höglund, Anna, 1964, et al.
(författare)
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Antibodies given orally in the neonatal period can affect the immune response for two generations: evidence for active maternal influence on the newborn's immune system.
- 1999
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Ingår i: Scandinavian journal of immunology. - 0300-9475. ; 50:6, s. 651-6
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Tidskriftsartikel (refereegranskat)abstract
- Two day old Wistar rats were tube fed with 1 or 10 micrograms of a mouse IgG1 monoclonal anti-idiotypic (a-Id) antibody that was directed against an anti-Escherichia coli-K13 capsular polysaccharide antibody. A control group was given 10 micrograms of an unrelated control antibody. Six weeks after the administration of antibodies, the rats were intestinally colonised with an ovalbumin (OVA)-producing E. coli O6K13 strain. At 8 weeks of age, the male rats (first generation) and the offsprings of the female rats (second generation), were parenterally immunised with OVA and dead wild type E. coli O6K13, and the immune response was followed. In the rats of the first generation, there were no major differences between the groups in the immune response to the bacterium. However, the offspring of the neonatally a-Id administered rats had a profoundly affected immune response to the idiotypically connected antigen K13, but also to other antigens on the bacteria. Thus, a-Id treatment in the first generation gave, in the second generation, a greatly enhanced serum antibody response to the spatially related antigens OVA and O6 LPS, as well as to the idiotypically connected antigen K13. Concurrently, the in vitro spleen cell proliferative response to both OVA and the wild type bacterium was lowered. Overall, greater effects were seen with the higher dose of a-Id. In conclusion, our results demonstrate that by giving monoclonal antibodies idiotypically connected to a single bacterial component to neonatal rats, one profoundly influence the immune response also to other-spatially related-bacterial antigens in their offsprings.
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| 15. |
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| 16. |
- Egebäck, Karl-Erik, et al.
(författare)
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Research on a Scania 11 liter ethanol fueled bus engine
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents research carried out on an alcohol fueled bus engine. The engine used was a six cylinder 11 liter compression ignition turbo- charged engine with an inter cooler. The research program included studies of the impact on the emissions when changing different engine components and different settings of the engine. A study of the impact on the engine performance and emissions when using different fuel compositions was also carried out. During the course of the work, the engine was equipped with oxidation catalysts of two different types, one of which was more efficient than the other concerning the oxidation of unburnt fuel related components. One of the main purposes of the research was to improve the emission characteristics of the engine by an optimization of the engine and its setting. The exhaust emissions were thoroughly characterized with respect to both regulated and unregulated emissions
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| 17. |
- Englund, Daniel, et al.
(författare)
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Metod- och kvalitetsbeskrivning för geografiskt fördelade emissioner till luft (submission 2022)
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige rapporterar årligen nationella utsläpp till luft till UNFCCC (FN:s klimatkonvention) och CLRTAP (UNECE:s konvention om gränsöverskridande luftföroreningar), så kallade submissioner. SMED har sedan rapporteringsåret 2001 ansvaret att på uppdrag av Naturvårdsverket ta fram allt dataunderlag och det mesta av tillhörande dokumentation för dessa rapporteringar. Förutom emissioner på nationell nivå finns även behov av data med högre geografisk upplösning. För regional uppföljning av miljömålen behövs emissioner på kommun- och länsnivå.Detta dokument utgör en metod- och kvalitetsbeskrivning av geografiskt fördelade emissioner för åren 1990, 2000, 2005, 2010 samt 2015-2020, rapporterade i submission 2022. Emissionerna presenteras i 54 olika sektorer uppdelade på nio huvudsektorer. Huvudsektorerna är El och fjärrvärme, Egen uppvärmning av bostäder och lokaler, Industri (energi och processer), Transporter, Arbetsmaskiner, Produktanvändning (inkl. lösningsmedel), Jordbruk, Avfall (inkl. avlopp) samt Utrikes transporter. De ämnen som ingår ges nedan. Notera att utsläpp av koldioxid enbart omfattar koldioxid med fossilt ursprung.Växthusgaser: CO2 (fossilt ursprung), CH4, N2O, HFC, PFC, SF6Metaller: Pb, Cd, Hg, As, Cr, Cu, Ni, Se, ZnPartiklar: PM2.5, PM10, TSP (Partiklar total), BC (sot)Övriga luftföroreningar: NOX, SOX, NH3, NMVOC, CO, dioxin, benso(a)pyren, PAH-4, HCB, PCBFör huvudsektorn Utrikes transporter fördelas eller redovisas inga växthusgaser geografiskt.Den geografiska fördelningen utförs huvudsakligen enligt konceptet ”topdown”. Detta innebär att emissioner bryts ner från en nationell totalemission för att uppnå en högre rumslig upplösning på lokal nivå. Nedbrytningen till högre rumslig upplösning kräver en geografisk begränsning av emissionerna och statistik på regional nivå.Metoden för geografisk fördelning tillåter för vissa utsläppskällor en hög rumslig upplösning (t.ex. för vägtrafik och industriprocesser). För flera sektorer är emellertid resultaten otillförlitliga om de ska studeras med högre upplösning än kommunnivå (i vissa fall även länsnivå). Resultaten från den geografiska fördelningen lagras i årsvisa emissionsdatabaser i SMHI:s tekniska system för luftvårdsarbete; Clair. Ur Clair exporteras emissionerna till Excel-tabeller på läns- och kommunnivå. Exempel på resultaten redovisas grafiskt på länsnivå och för huvudsektorer. Emissionerna presenteras även på karta, samt i diagram. Publicering av resultaten sker via SMHI:s datavärdskap hemsida: www.nationellaemissionsdatabasen.smhi.seFör att ta del av information om enskilda industrier/verksamheter så kan dessa hittas på http://utslappisiffror.naturvardsverket.se.Arbetet med geografisk fördelning av Sveriges utsläpp till luft är sedan 2007 ett årligt projekt. Projektet har ett långsiktigt perspektiv med målsättningen att stegvis förbättra kvaliteten på geografiskt upplösta emissionsdata. Resultaten för alla sektorer presenteras med samma geografiska upplösning även om kvaliteten varierar. På grund av detta krävs det att användare av dessa emissionsdata går igenom kvalitetsbeskrivningen och bedömer om osäkerheterna är acceptabla för den aktuella tillämpningen. Kvalitetsklassningen kan ge vägledning om de osäkerheter som finns på huvudsektornivå (en kvalitetsbeskrivning finns även i avsnitten i detta dokument för varje ingående undersektor). Genom retroaktiva omräkningar säkerställs att metodförändringar inte orsakar trendbrott. I vissa fall har dock tillgängliga grunddata (t.ex. statistik) förändrats, vilket kan leda till icke-reella trendbrott.
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| 18. |
- Englund, Daniel, et al.
(författare)
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Metod- och kvalitetsbeskrivning för geografiskt fördelade emissioner till luft (submission 2023)
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige rapporterar årligen nationella utsläpp till luft till UNFCCC (FN:s klimatkonvention) och CLRTAP (UNECE:s konvention om gränsöverskridande luftföroreningar), så kallade submissioner. SMED har sedan rapporteringsåret 2001 ansvaret att på uppdrag av Naturvårdsverket ta fram allt dataunderlag och det mesta av tillhörande dokumentation för dessa rapporteringar. Förutom emissioner på nationell nivå finns även behov av data med högre geografisk upplösning. För regional uppföljning av miljömålen behövs emissioner på kommun- och länsnivå. Detta dokument utgör en metod- och kvalitetsbeskrivning av geografiskt fördelade emissioner för åren 1990, 2000, 2005, 2010 samt 2015-2021, rapporterade i submission 2023. Emissionerna presenteras i 54 olika sektorer uppdelade på nio huvudsektorer.Den geografiska fördelningen utförs huvudsakligen enligt konceptet ”top-down”. Detta innebär att emissioner bryts ner från en nationell totalemission för att uppnå en högre rumslig upplösning på lokal nivå. Nedbrytningen till högre rumslig upplösning kräver en geografisk begränsning av emissionerna och statistik på regional nivå.Metoden för geografisk fördelning tillåter för vissa utsläppskällor en hög rumslig upplösning (t.ex. för vägtrafik och industriprocesser). För flera sektorer är emellertid resultaten otillförlitliga om de ska studeras med högre upplösning än kommunnivå (i vissa fall även länsnivå). Resultaten från den geografiska fördelningen lagras i årsvisa emissionsdatabaser i SMHI:s tekniska system för luftvårdsarbete; Clair. Ur Clair exporteras emissionerna till Excel-tabeller på läns- och kommunnivå.Rapporten beskriver större förändringar som har skett i nationella totalemissioner samt större förändringar i fördelningsmetodik jämfört med föregående år.
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| 19. |
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| 20. |
- Eriksson, Gunnar, et al.
(författare)
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Combustion characterization of rapeseed meal and possible combustion applications
- 2009
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 23:8, s. 3930-3939
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Tidskriftsartikel (refereegranskat)abstract
- A future shortage of biomass fuel can be foreseen. The production of rapeseed oil for a number of purposes is increasing, among others, for biodiesel production. A byproduct from the oil extraction process is rapeseed meal (RM), presently used as animal feed. Further increases in supply will make fuel use an option. Several energy companies have shown interest but have been cautious because of the scarcity of data on fuel properties, which led to the present study. Combustion-relevant properties of RM from several producers have been determined. The volatile fraction (74 ± 0.06%wtds) is comparable to wood; the moisture content (6.2−11.8%wt) is low; and the ash content (7.41 ± 0.286%wtds) is high compared to most other biomass fuels. The lower heating value is 18.2 ± 0.3 MJ/kg (dry basis). In comparison to other biomass fuels, the chlorine content is low (0.02−0.05%wtds) and the sulfur content is high (0.67−0.74%wtds). RM has high contents of nitrogen (5.0−6.4%wtds), phosphorus (1.12−1.23%wtds), and potassium (1.2−1.4%wtds). Fuel-specific combustion properties of typical RM were determined through combustion tests, with an emphasis on gas emissions, ash formation, and potential ash-related operational problems. Softwood bark was chosen as a suitable and representative co-combustion (woody) fuel. RM was added to the bark at two levels: 10 and 30%wtds. These mixtures were pelletized, and so was RM without bark (for durability mixed with cutter shavings, contributing 1%wt of the ash). Each of these fuels was combusted in a 5 kW fluidized bed and an underfed pellet burner (to simulate grate combustion). Pure RM was combusted in a powder burner. Emissions of NO and SO2 were high for all combustion tests, requiring applications with flue gas cleaning, economically viable only at large scale. Emissions of HCl were relatively low. Temperatures for initial bed agglomeration in the fluidized-bed tests were high for RM compared to many other agricultural fuels, thereby indicating that RM could be an attractive fuel from a bed agglomeration point of view. The results of grate combustion suggest that slagging is not likely to be severe for RM, pure or mixed with other fuels. Fine-mode particles from fluidized-bed combustion and grate combustion mainly contained sulfates of potassium, suggesting that the risk of problems caused by deposit formation should be moderate. The chlorine concentration of the particles was reduced when RM was added to bark, potentially lowering the risk of high-temperature corrosion. Particle emissions from powder combustion of RM were 17 times higher than for wood powder, and the fine-mode fraction contained mainly K-phosphates known to cause deposits, suggesting that powder combustion of RM should be used with caution. A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases.
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| 21. |
- Eriksson, Gunnar, et al.
(författare)
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Förbränningskarakterisering av rapsmjöl och förslag till optimalt nyttjande i olika förbränningsanläggningar
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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 (<1 µm) from powder combustion contain mainly K, P and S. The only identified crystalline phase was K2SO4, suggesting that most phosphorus was in the amorphous phase, i.d. most probably molten. The deposit formation on a cooled probe was studied during the fluidized bed and powder combustion experiments. The fine particles deposited during fluidised bed combustion contained K, Cl and S. When bark was combusted in the fluidised bed, the coarse fraction contained Ca and Si, when rape seed meal in different mixes was combusted this changed to P, K, Ca and Mg. The deposits formed during combustion of rape seed meal in the powder burner were mainly made up of phosphates (Ca-, Mg/K-, Ca/Mg-phosphates) and MgO. Sintered material (slag) from grate combustion of bark contained mainly Si, Ca, K and Al, probably as silicates. Adding rape seed meal tended to increase P, Ca and Mg while Si and Ca content tended to decrease. Through XRD a number o crystalline phases in the sintered material and the rest of the bottom ashes could be identified. NO emissions from the combustions tests increased two to four times with rape seed meal compared to typical wood fuels. For the fluidised bed test, SO2 concentrations were rather high for the rape seed meal pellets (with 20 percent wood), still only about 20 percent of the sulphur in the fuel formed SO2. For the grate combustion and powder burner combustion, 60 percent and 70 percent of the sulphur respectively formed SO2. HCl emissions were low for all tests. The rather high emissions of NOx and SOx mean that the material should be used in large-scale facilities with external SOx and NOx cleaning. In smaller facilities, the material may be used in small amounts mixed with other fuels. The risk of slagging is not very high, and should not rule out grate combustion of pellets with rape seed meal mixed with other fuels. The risk of corrosion of superheater surfaces during combustion is probably low since the smaller-size particles formed at fluidised bed combustion and grate combustion contain K2SO4. However, a large fraction of the particles formed in powder burner combustion probably contains low temperature melting K2PO4, making the risk for deposit formation significant. Rape seed meal for powder burner applications should be used with care. The content of phosphorus in the material may be an advantage when mixes of rape seed meal and other fuels are considered. The high affinity between potassium and phosphorus means that more sulphur in the fuel will be available for sulphatising of any KC. (formed from combustion of many forest and agricultural fuels). Use of rape seed meal as a sulphur containing additive could thus be an option. For grate combustion and fluidised bed combustion, addition of rape seed meal may reduce the risk of slagging and bed agglomeration, respectively. Full scale tests in fluidised beds or grate combustors with problematic biofuels (containing Cl and K) would be useful to test whether ash-reduced operational problems could be reduced through the addition of rape seed meal.
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| 22. |
- Furusjö, Erik, et al.
(författare)
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Co-gasification of pyrolysis oil and black liquor - a new track for production of chemicals and transportation fuels from biomass
- 2015
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Konferensbidrag (refereegranskat)abstract
- Pressurized oxygen-blown entrained flow black liquor (BL) gasification, the Chemrec technology, has been demonstrated in a 3 MWth pilot plant in Piteå, Sweden for more than 25,000 h. The plant is owned and operated by Luleå University of Technology since 2013. It is well known that catalytic activity of alkali metals is important for the high reactivity of black liquor, which leads to a highly efficient BL gasification process. The globally available volume of BL is however limited and strongly connected to pulp production. By co-gasifying pyrolysis oil (PO) with BL it is possible to utilize the catalytic activity also for PO conversion to syngas. Adding PO leads to larger feedstock flexibility with the possibility of building larger biofuels plants based on BL gasification technology. This presentation summarizes new results from research activities aimed at developing and assessing the PO/BL co-gasification process. Results from laboratory experiments with PO/BL mixtures show that pyrolysis behavior and char gasification reactivity are similar to pure BL. This means that the decrease in the alkali metal concentration due to the addition of PO in the mixture does not decrease the reactivity. Pure PO is much less reactive. Mixing tests show that the fraction of PO that can be mixed into BL is limited by lignin precipitation as a consequence of PO acidity. Pilot scale PO/BL co-gasification experiments have been executed following design and construction of a new feeding system to allow co-feeding of PO with BL. The results confirm the conclusions from the lab scale study and prove that the co-gasification concept is practically applicable. Process performance of the pilot scale co-gasification process is similar to gasification of BL only with high carbon conversion and clean syngas generation. This indicates that the established BL gasification technology can be used for co-gasification of PO and BL without major modifications.
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| 23. |
- Furusjö, Erik, 1972-, et al.
(författare)
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Mixing of Fast Pyrolysis Oil and Black Liquor : Preparing an Improved Gasification Feedstock
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 30:12, s. 10575-10582
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Tidskriftsartikel (refereegranskat)abstract
- Co-gasification of fast pyrolysis oil and black liquor can be used to increase the size and improve profitability of pulp mill integrated biorefineries. The acids present in pyrolysis oil limit the amount that can be mixed into black liquor without causing precipitation of the black liquor dissolved lignin. This work shows that a simple model based on pyrolysis oil total acid number, including weak phenolic acids, can be used to predict the maximum pyrolysis oil fraction in blends. The maximum oil fraction is 20-25% for typical pyrolysis oil but can be increased up to at least 50% mass, corresponding to 70% energy, by addition of base. Thermodynamic equilibrium calculations are used to understand the effects of blend composition, including any added base, on the performance of a commercial scale gasification process. A substantial increase in overall gasification efficiency is observed with increasing pyrolysis oil fraction.
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| 24. |
- Gabra, M., et al.
(författare)
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Evaluation of cyclone gasifier performance for gasification of sugar cane residue : Part 1: Gasification of bagasse
- 2001
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 21:5, s. 351-369
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Tidskriftsartikel (refereegranskat)abstract
- A method for avoiding excessive amount of alkali compounds and carryover particles in producer gas from gasification of sugar cane residue has been studied and evaluated. The cane sugar residue is gasified in a two-stage combustor at atmospheric pressure, where the first stage is a cyclone gasifier. The cyclone works as particle separator as well. This paper covers the results obtained for gasification of bagasse. Bagasse powder was injected into the cyclone with air and steam as transport medium. The gasification tests were made with two feeding rates, 39 and 52 kg/h. Seven experiments were conducted with the equivalence ratio being varied. The heating values of the producer gas are sufficient for stable gas turbine combustion. About 60-70% of the alkali input with fuel was separated from the producer gas in the cyclone. However the total alkali contents of the producer gas was found to be higher than in ABB Stal PFBC gas turbines and at least an order of magnitude higher than what is required by most gas turbine manufacturers for operation of a gas turbine. The carryover particles concentrations in the producer gas were found to be in the range of that for PFBC gas turbines, but higher than what is required by most gas turbine manufacturers for operation of a gas turbine. Samples studied with scanning electronic microscope give indication that most of the carryover particles are below 10 μm in size. Fly ash-melting tests have not shown any major ash melting up to 1200°C, but it was found that some of the particles entrained with producer gas were partially melted. Integrated experiments with a gas turbine need to be done for accurate evaluation of the possibilities to use the producer gas from the gasification of bagasse to run a gas turbine without problems of hard deposits and corrosion on the turbine blades. In part 2 of this two-part paper the results from cane trash gasification tests are reported. © 2001 Published by Elsevier Science Ltd.
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| 25. |
- Gabra, M., et al.
(författare)
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Evaluation of cyclone gasifier performance for gasification of sugar cane residue : Part 2: Gasification of cane trash
- 2001
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 21:5, s. 371-380
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Tidskriftsartikel (refereegranskat)abstract
- In Part 1 of this two-part paper, results from gasification of bagasse in a cyclone gasifier have been reported. In this paper results from gasification of cane trash in the same cyclone gasifier are presented. The cane trash powder is injected into the cyclone with air as transport medium. The gasification tests were made with two feeding rates, 39 and 46 kg/h at two equivalence ratios of 0.25 and 0.20 and the gasification temperature ranging from 820°C to 850°C. It was found that the heating value of the producer gas is in the range of 4.5-4.8 MJ/Nm3(dry gas), which is sufficient for stable gas turbine combustion. Significant alkali separation has been achieved in the cyclone stage. However, the alkali levels and carryover particle concentrations in the producer gas were found to be higher than allowable in a gas turbine. Despite high ash melting temperatures found by the TGA-DTA, deposition problems cannot be excluded since some carryover panicles in the producer gas seem to have been melted and since some gasification of K and Na compounds is indicated. As an overall assessment, cane trash appears as a more problematic fuel than bagasse for this application. Integrated experiments with a gas turbine need to be done for accurate evaluation of the possibilities to use the producer gas from the gasification of cane trash to run a gas turbine without problems of hard deposits and corrosion on the turbine blades. © 2001 Published by Elsevier Science Ltd.
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| 26. |
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| 27. |
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| 28. |
- Iisa, Kristiina, et al.
(författare)
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Chemical and physical characterization of aerosols from fast pyrolysis of biomass
- 2019
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier B.V.. - 0165-2370 .- 1873-250X. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Biomass fast pyrolysis vapors contain a significant quantity of persistent aerosols, which can impact downstream processing by e.g. fouling of surfaces and deposition on downstream catalysts. In this study, aerosol concentrations and size distributions were measured by an impactor in two pyrolysis systems, a bench-scale fluidized-bed pyrolyzer and a pilot-scale cyclone pyrolyzer. In both units, the mass-based mode aerosol diameter was approximately 1 μm before aerosol collection devices in cooled vapors of 300–370 K but the number-based median was < 0.1 μm. Aerosols < 1 μm were formed and aerosols > 1 μm deposited during cooling of pyrolysis vapors from 620 to 370 K in the fluidized-bed pyrolysis system. The oil fraction collected from the aerosols constituted approximately 40 wt% of the total oils collected in both systems. Compared to the total collected oil, the oil fraction from the aerosols was enriched in lignin-derived components and anhydrosugars and had lower concentrations of low molecular weight cellulose derived oxygenates, such as hydroxyketones.
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| 29. |
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| 30. |
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| 31. |
- Karlsson, Malin, et al.
(författare)
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"Tolerosomes” are produced by intestinal epithelial cells
- 2001
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Ingår i: European Journal of Immunology. ; 31, s. 2892-2900
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Tidskriftsartikel (refereegranskat)abstract
- The development of immunological tolerance to orally fed antigens depends on the sampling, processing and transportation events followed in the intestinal epithelium. We present here a description of a ’’tolerosome’’: a supra-molecular, exosome-like structure assembled in and released from the small intestinal epithelial cell. The tolerosome is a e 40 nm large vesicular structure that carries MHC class II (MHC II) with bound antigenic peptides sampled from the gut lumen. Tolerosomes isolated from serum shortly after antigen feeding or from an in vitro pulsed intestinal epithelial cell line are fully capable of inducing antigen specific tolerance in naive recipient animals. Purified tolerosomes represent a structure by which fed antigens can be efficiently presented to the immune system. Removal of the tolerosomes from serum by ultracentrifugation or absorption of MHC II results in abrogated tolerance development.
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| 32. |
- Khwaja, Salik, et al.
(författare)
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Entrained flow gasification of torrefied lignocellulosic biomass
- 2016
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Ingår i: Papers of the 24TH European Biomass Conference. - Amsterdam : ETA Florence Renewable Energies. ; , s. 1138-1142, s. 1138-1142
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Konferensbidrag (refereegranskat)abstract
- An extensive evaluation program was carried out within the European SECTOR project to evaluate the feasibility of torrefied and densified biomass in available entrained flow gasifiers. Different entrained flow reactors (both atmospheric and pressurized) in different scales, from lab scale to a 240 MW industrial gasifier were used for evaluation of torrefied materials as feedstock. Total behaviours of the new fuel throughout the whole supply chains and the EFG systems were evaluated and documented, including process behaviours in terms of operation, gas quality, products of incomplete gasification, etc. Results showed a significant improvement in fuel properties in terms of storage, logistics, milling and feeding behaviour by torrefaction and densification. Entrained flow gasification of the torrefied biomass was also shown to be feasible without any major showstoppers, even improving the gasification processes. Production of tars and other products of incomplete gasification were often found significantly reduced during gasification of torrefied material.
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| 33. |
- Lundgren, Joakim, et al.
(författare)
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Combustion of horse manure for heat production
- 2009
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 100:12, s. 3121-3126
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Tidskriftsartikel (refereegranskat)abstract
- The main objectives of this paper have been to evaluate the use of horse manure and wood-shavings as a fuel for heat production and to provide sets of data on the chemical composition, ash characteristics and ash forming elements of the fuel. Another objective has been to investigate the possibility to use the ash as fertiliser by analysing the heavy metal and nutrient contents. The results showed that the fuel is well suited for combustion for heat production causing low emissions of products of incomplete combustion. The emissions of NOx were however high due to the high content of fuel bound nitrogen. Emissions of CO and NOx were typically in the range of 30-150 mg/Nm3 and 280-350 mg/Nm3 at 10 vol% O2, respectively. The analysis of the ash showed on sufficiently low concentration of heavy metals to allow recycling. © 2009 Elsevier Ltd. All rights reserved.
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| 34. |
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| 35. |
- Muala, Ala, et al.
(författare)
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Acute exposure to wood smoke from incomplete combustion - indications of cytotoxicity
- 2015
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Ingår i: Particle and Fibre Toxicology. - : Springer Science and Business Media LLC. - 1743-8977. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Smoke from combustion of biomass fuels is a major risk factor for respiratory disease, but the underlying mechanisms are poorly understood. The aim of this study was to determine whether exposure to wood smoke from incomplete combustion would elicit airway inflammation in humans. Methods: Fourteen healthy subjects underwent controlled exposures on two separate occasions to filtered air and wood smoke from incomplete combustion with PM1 concentration at 314 mu g/m(3) for 3 h in a chamber. Bronchoscopy with bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial mucosal biopsies was performed after 24 h. Differential cell counts and soluble components were analyzed, with biopsies stained for inflammatory markers using immunohistochemistry. In parallel experiments, the toxicity of the particulate matter (PM) generated during the chamber exposures was investigated in vitro using the RAW264.7 macrophage cell line. Results: Significant reductions in macrophage, neutrophil and lymphocyte numbers were observed in BW (p < 0.01, < 0.05, < 0.05, respectively) following the wood smoke exposure, with a reduction in lymphocytes numbers in BAL fluid (< 0.01. This unexpected cellular response was accompanied by decreased levels of sICAM-1, MPO and MMP-9 (p < 0.05, < 0.05 and < 0.01). In contrast, significant increases in submucosal and epithelial CD3+ cells, epithelial CD8+ cells and submucosal mast cells (p < 0.01, < 0.05, < 0.05 and < 0.05, respectively), were observed after wood smoke exposure. The in vitro data demonstrated that wood smoke particles generated under these incomplete combustion conditions induced cell death and DNA damage, with only minor inflammatory responses. Conclusions: Short-term exposure to sooty PAH rich wood smoke did not induce an acute neutrophilic inflammation, a classic hallmark of air pollution exposure in humans. While minor proinflammatory lymphocytic and mast cells effects were observed in the bronchial biopsies, significant reductions in BW and BAL cells and soluble components were noted. This unexpected observation, combined with the in vitro data, suggests that wood smoke particles from incomplete combustion could be potentially cytotoxic. Additional research is required to establish the mechanism of this dramatic reduction in airway leukocytes and to clarify how this acute response contributes to the adverse health effects attributed to wood smoke exposure.
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| 36. |
- Muala, Ala, et al.
(författare)
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Bronchial mucosal inflammation in healthy subjects after exposure to wood smoke from incomplete combustion
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Indoor smoke from combustion of solid biomass fuel is a major risk factor for respiratory disease worldwide. The mechanisms by which wood smoke exhibits its effects on human health are not well understood. The aim of this study was to determine whether exposure to wood smoke produced from incomplete combustion would elicit an airway inflammatory response.Methods Fourteen healthy subjects underwent controlled chamber exposure on two occasions to filtered air and to sooty wood smoke (PM1 ~ 314 μg/m3), generated by a common Nordic wood stove firing birch logs. The study was performed with a double-blind randomized cross-over design and the subjects alternated between exercise (VE=20 L/min/m2) and rest at 15-minute intervals for 3 hours. Bronchoscopies were performed 24 hours after each exposure where bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial biopsies were taken. Differential cell counts and soluble components were analyzed in BW and BAL. Bronchial mucosal biopsies were analyzed using immunohistochemistry. Blood tests for inflammatory markers were sampled pre-exposure as well as at 24 and 44-hour time points post-exposure. Spirometry and Fraction of exhaled nitric oxide (FENO) were performed before, immediately after and 24 hours after each exposure.Results There was a significant increase in submucosal and epithelial CD3+ lymphocytes (p<0.01 and <0.05 respectively), together with CD8+ cells in the epithelium (p<0.05) after exposure to wood smoke compared to filtered air. Mast cells were also significantly increased in the submucosa (p<0.01) after wood smoke exposure.There were significant reductions in macrophages, neutrophils and lymphocytes in BW after exposure to wood smoke compared to filtered air, accompanied by decreased levels of soluble Intercellular Adhesion Molecule-1 (sICAM-1), myeloperoxidase (MPO) and matrix metalloproteinase-9 (MMP-9). No significant effects on cell numbers or acute inflammatory markers were demonstrated in BAL fluid or peripheral blood. Lung function and FENO were not affected by exposure to wood smoke.Conclusions Wood smoke exposure caused a significant increase in bronchial epithelial and submucosal CD3+ lymphocytes together with an increase in mucosal mast cells. Further examination revealed a significant increase in CD8+ lymphocytes within the epithelium. Unexpectedly there were no indications of any neutrophilic airway response or recruitment of alveolar macrophages. BW cell numbers, MPO and MMP-9 levels were also significantly reduced after wood smoke exposure. Further research is needed to determine the precise role of these events in relationship to the adverse health effects attributed to wood smoke exposure.
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| 37. |
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| 38. |
- Muala, Ala, et al.
(författare)
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Respiratory Tract Deposition of Inhaled Wood Smoke Particles in Healthy Volunteers
- 2015
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Ingår i: Journal of Aerosol Medicine. - : Mary Ann Liebert Inc. - 1941-2711 .- 1941-2703. ; 28:4, s. 237-246
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Tidskriftsartikel (refereegranskat)abstract
- Background: Respiratory tract deposition of air pollution particles is a key to their adverse health effects. This study was aimed to determine the size-resolved deposition fraction (DF) of sooty wood smoke particles in the lungs of healthy subjects. The type of wood smoke investigated is typical for household air pollution from solid fuels, which is among the largest environmental health problems globally.Methods: Twelve healthy volunteers inhaled diluted wood smoke from incomplete soot-rich combustion in a common wood stove. The DF of smoke particles (10–500 nm) was measured during three 15-min exposures in each subject during spontaneous breathing. Lung function was measured using standard spirometry.Results: The total DFs by particle number concentration were 0.34±0.08. This can be compared with DFs of 0.21–0.23 in healthy subjects during previous experiments with wood pellet combustion. For particle mass, the total DFs found in this study were 0.22±0.06. DF and breathing frequency were negatively correlated as expected from model calculations (p<0.01).Conclusions: The DF of the investigated sooty wood smoke particles was higher than for previously investigated particles generated during more efficient combustion of biomass. Together with toxicological studies, which have indicated that incomplete biomass combustion particles rich in soot and polycyclic aromatic hydrocarbons (PAHs) are especially harmful, these data highlight the health risks of inadequate wood combustion.
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| 39. |
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| 40. |
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| 41. |
- Olwa, Joseph, et al.
(författare)
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Potassium retention in updraft gasification of wood
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:11, s. 6718-6724
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Tidskriftsartikel (refereegranskat)abstract
- The release of compounds of K with producer gas during biomass gasification is known to play significant roles in fouling and high-temperature corrosion in boilers and high-temperature heat exchangers as well as blades in gas turbines that use producer gas as fuel. These phenomena are a major setback in the application of biomass fuel in combination with advanced process conditions. Updraft gasification provides gas filtering by the fuel bed with a gas cooling effect, conditions anticipated to create an avenue for K retention in the gasifier. The objective of this study was to determine the K retention potential of such gasifiers during wood gasification. Samples for the determination of the fate of K compounds included in the feedstock were collected from the generated producer gas using Teflon filters and gas wash bottles and also from wall deposits and ash residues. Analyses of samples were carried out using inductively coupled plasma-atomic emission spectrometry/mass spectrometry and X-ray diffraction methods. The finding was that about 99% of K was retained in the gasifier. K was found in the ash samples as a crystalline phase of K 2Ca(CO3)2(s) (fairchildite). A possible reaction mechanism leading to the formation of K2Ca(CO 3)2 is discussed in the paper. The 1% K understood as released, equivalent to 1200 ppbw content of K entrained in the producer gas stream, exceeds a known limit for application of the gas in conventional gas turbines. This would suggest application of the gas in an externally fired gas turbine system, where some limited K and other depositions in the heat exchanger can be relatively easy to handle.
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Pettersson, Esbjörn, et al.
(författare)
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Design changes in a fixed bed pellet combustion device : effects of temperature and residence time on emission performance
- 2010
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 24:2, s. 1333-1340
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Tidskriftsartikel (refereegranskat)abstract
- The use of wood fuel pellets has proven to be well-suited for the small-scale market, enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still, a potential for further emission reduction exists, and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM), is important. The objective of the present work was to determine the effect of design changes, i.e., increasing the temperature and/or residence time, on the emission performance and characteristics for a pellet combustion device using a laboratory fixed-bed reactor (<5 kW). The temperature and residence time after the bed section were varied according to statistical experimental designs (650-950 °C and 0.5-3.0 s) with the emission responses: CO, organic gaseous carbon (OGC), NO, volatile organic compounds (VOCs, 20 compounds), PAHs (43 compounds), PMtot mass concentration, fine particle mass/count median diameter (MMD and CMD), and number concentration. The temperature was negatively correlated with the emissions of all studied PIC, with limited effects of the residence time. The PMtot emissions of 15-20 mg/MJ were in all cases dominated by fine (<1 μm) particles of K, Na, S, Cl, C, O, and Zn. An increased residence time resulted in increased fine particle sizes (i.e., MMD and CMD) and decreased number concentrations. The importance of a high temperature (>850 °C) in the bed zone with intensive, air-rich, and well-mixed conditions was illustrated for wood pellets combustion with almost a total depletion of all studied PIC. The importance of the residence time was shown to be limited, and the results emphasize the need for further verification studies and technology development work.
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| 46. |
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| 47. |
- Pettersson, Esbjörn, et al.
(författare)
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Exhaust emissions from an ethanol-fueled diesel engine with EGR
- 1994
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Ingår i: Proceedings. - Croydon : Automotive automation. - 0947719717
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Konferensbidrag (refereegranskat)abstract
- Effects of Exhaust Gas Recirculation (EGR) on exhaust emissions in an ethanol-fueled direct injection diesel engine have been studied at different injection timings and compression ratios. In addition to regulated emissions the unregulated components formaldehyde, acetaldehyde, and ethanol were analyzed. EGR decreases nitrogen oxide (NOx) emissions substantially and increases carbon monoxide (CO) emission. Total hydrocarbon (THC) emissions, as measured with a flame ionization detector (FID), are fairly constant with increasing EGR rates up to a point where the combustion deteriorates and THC emissions increase rapidly. At low and medium load the emissions of form- and acetaldehyde increase substantially even at EGR rates where THC emissions still are constant. Low aldehyde emissions are favored by advanced injection timing and high compression ratios. The results indicate that the increase in aldehyde emissions due to EGR will decrease under those conditions
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| 48. |
- Pettersson, Esbjörn
(författare)
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Exhaust gas emissions from ethanol fueled heavy duty
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of the project was to contribute to the development of more efficient and better suited catalysts for ethanol fueled diesel vehicles, by characterization of the emissions of both regulated and unregulated exhaust emission components at different driving conditions for a bus engine. Measurements on three commercial and one prototype catalyst were performed at 22 'steady state' loading points. The measurements included the regulated emission components carbon monoxide, hydrocarbons and nitrogen oxides and the non-regulated emission components ethanol, formaldehyde, acetaldehyde, acetic acid and some light hydrocarbons. The investigation shows that there are large differences between the commercial catalysts regarding the oxidation capacity and the selectivity. One of the catalysts showed a very high oxidation capacity but relatively low selectivity. The emissions of both nitrogen dioxide and acetic acid became with this catalyst considerably larger than for the other two. On the other hand did the emission of acetaldehyde become lower than for the other two. The catalyst which were developed especially for ethanol fueled diesel vehicles showed somewhat higher selectivity for ethanol oxidation at most loading points. This gave very low emissions of acetic acid and low emissions of acetaldehyde. This catalyst showed on the other hand some oxidation of NO to NO(sub 2). Ageing in diesel exhaust did not impair the performance of this catalyst.
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| 49. |
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| 50. |
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