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  • 1.
    Boström, Dan
    et al.
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Eriksson, Gunnar
    Boman, Christoffer
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash transformations in fluidized-bed combustion of rapeseed meal2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 5, p. 2700-2706Article in journal (Refereed)
    Abstract [en]

    The global production of rapeoil is increasing. A byproduct is rapeseed meal that is a result of the oil extraction process. Presently the rapeseed meal mainly is utilized as animal feed. An interesting alternative use is, however, energy conversion by combustion. This study was undertaken to determine the combustion properties of rapeseed meal and bark mixtures in a bubbling fluidized bed, with emphasis on gas emissions, ash formation, -fractionation and -interaction with the bed material. Due to the high content of phosphorus in rapeseed meal the fuel ash is dominated by phosphates, in contrast to most woody biomass where the ash is dominated by silicates. From a fluidized bed combustion (FBC) point of view, rapeseed meal could be a suitable fuel. Considering FBC agglomeration effects, pure rapeseed meal is in level with the most suitable fuels, as earlier tested by the methods utilized in the present investigation. The SO2 emission, however, is higher than most woody biomass fuels as a direct consequence of the high levels of sulfur in the fuel. Also the particulate matter emission, both submicron and coarser particles, is higher. Again this can be attributed the high ash content of rapeseed meal. The high abundance of SO2 is apparently effective for sulfatization of KCl in the flue gas. Practically no KCl was observed in the particulate matter of the flue gas. A striking difference in the mechanisms of bed agglomeration for rapeseed meal compared to woody biomass fuels was also observed. The ubiquitous continuous layers on the bed grains found in FBC combustion of woody biomass fuels was not observed in the present investigation. Instead very thin and discontinuous layers were observed together with isolated partly melted bed ash particles. The latter could occasionally be seen as adhered to the quartz bed grains. Apparently the bed agglomeration mechanism, that obviously demanded rather high temperatures, involved more of adhesion by partly melted ash derived potassium-calcium phosphate bed ash particles/droplets than direct attack of gaseous alkali on the quartz bed grains forming potassium-calcium silicate rich bed grain layers. An explanation could be found in the considerable higher affinity for base cations of phosphorus than silicon. This will to a great extent withdraw the present basic oxides from attacking the quartz bed grains with agglomeration at low temperatures as a result.

  • 2.
    Boström, Dan
    et al.
    Umeå universitet.
    Eriksson, Gunnar
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Boman, Christoffer
    Umeå universitet.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bench-scale fluidized bed combustion of rapeseed meal2008In: From Research to industry and markets: 16th European Biomass Conference & Exhibition ; proceedings of the international conference held in Valencia, Spain, 2 - 6 June 2008 / [ed] J. Schmid, Florence: ETA - Renewable Energies , 2008, p. 1380-1385Conference paper (Refereed)
  • 3.
    Eriksson, Gunnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Combustion of solid waste from wood-based ethanol production2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The solid residue from wood-based ethanol production has a low ash content and high heating value, making it interesting for combustion applications, e.g. small-scale appliances and gas turbines. Combustion and gasification properties have been studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Char combustion rate data obtained could be used in combustion simulations. TGA and DTA data are useful for comparison with other fuels where data are available for similar heating rates. One possible use is direct-firing of gas turbines for Combined Heat and Power (CHP) at the site of the ethanol plant. Another possible use of the material is for the production of fuel pellets. A combustion test with a 150 kW powder burner has been done. Fuel feeding and combustion were stable. The average concentration of CO in the stack gas was 8 mg/MJ, the averag concentration of NOx was 59 mg/MJ and the average total hydrocarbon concentration was below 1 ppm, at an average O2 concentration of 4.6 per cent. Process parameters, investments, costs and revenues for these two production options have been estimated. The conclusion is that CHP is the most profitable use, although the uncertainties in estimated costs are considerable. Reductions of greenhouse gas emissions are decidedly larger for the CHP option. It has been concluded that CHP production is an option worth pursuing further. The technical feasibility of using the material for direct-firing of a gas turbine remains to be established however.

  • 4.
    Eriksson, Gunnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Klarar Luleå miljömålen?: utsläpp av svaveldioxid, kväveoxider och kolväten inom Luleå kommun1993Report (Other academic)
  • 5.
    Eriksson, Gunnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Residues from biochemical production of transport biofuels in Northern Europe: combustion properties and applications2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Residues from biochemical production of liquid transport biofuels will probably become available for energy use if more gasoline and diesel is substituted. For processes used in northern Europe they amount to 35-65 % of the feedstock energy and despite interest from energy companies, their fuel properties are largely unknown. Combustion-relevant material properties have been characterized and fuel-specific combustion properties determined for powder-, grate- and fluidized bed combustion. Suitable combustion applications have been identified. A techno-economic evaluation of utilization of a selected residue for supplying process heat and electricity to the transport biofuel production, combined with sale of surplus energy has been done. Residues studied are rape-seed meal (RM) from biodiesel production, wheat distillers dried grain with solubles (wheat DDGS) from grain-based ethanol production and hydrolysis residue (HR) from wood-based ethanol production. For RM and wheat DDGS, mixtures with typical forest- and agricultural fuels were also studied. Combustion experiments were performed in a fluidized (quartz) bed (5 kW), an under-fed pellet burner (12 kW), and in a powder burner (150 kW).The calorific value for HR was higher than for wood, for RM and wheat DDGS it was similar to wood. More char was produced from HR, otherwise TGA results showed that thermal kinetics was similar to wood for all fuels. All pulverized residues had better feeding properties than wood powder. While RM and wheat DDGS ash contents were higher than for most common forest and also for some agricultural fuels, HR mostly had very low contents of ash, alkali, Cl, S and N. RM and DDGS had high concentrations of S, N, K and P compared to most other biomass fuels. RM had higher Ca and Mg concentrations than DDGS. The Cl content of wheat DDGS was similar to wheat straw, while RM had a lower Cl content, similar to wood. Combustion of all pulverized residues was stable with CO emissions not higher than for wood powder. While the bed agglomeration tendency of RM was low and comparable to many forest fuels the wheat DDGS bed agglomeration tendency was high and comparable to wheat straw. The K, P and Si contents of wheat DDGS formed layers of K-phosphates/silicates on the quartz grain particles, with low melting temperatures and therefore sticky, resulting in bed agglomeration. For RM, this effect was mitigated by the considerable Ca and Mg concentrations, making the layers formed less sticky, despite the high K and P concentrations. For basically the same reason, the slag formation tendency of RM was moderate and comparable to many forest fuels while wheat DDGS had a slag formation tendency which was even higher than for typical wheat straw. HR had very low bed agglomeration and slagging tendencies.For RM and wheat DDGS, emissions of NO and SO2 were generally high, for HR considerably lower. While HCl emissions for RM were low, they were relatively high for fluidized bed combustion of wheat DDGS. Particle emissions from RM and wheat DDGS were generally high. For powder combustion of RM and wheat DDGS, particle emissions were 15-20 times higher than for wood. The particle emissions from combustion of HR were generally low. For fluidized bed- and grate combustion of RM the finer particles (< 1 μm) contained mainly alkali sulfates. RM addition to bark tended to lower the particle Cl concentrations, potentially lowering the risk of high-temperature corrosion. For fluidized bed combustion of wheat DDGS and wheat DDGS-mixtures the finer particles contained mainly K and S. The Cl concentrations of the fine particles in fluidized bed combustion were reduced when wheat DDGS where added to logging residues and wheat straw in fluidized bed combustion. In grate combustion the Cl- and P-concentrations in the finer particles during combustion of the wheat DDGS-mixtures were considerable higher than during fluidized bed combustion. The fine particles from powder combustion of RM mainly contained P and K, while they mainly contained K, P, Cl, Na and S from wheat DDGS (apart from C and O).A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K in large-scale fluidized-bed and grate combustors for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases. Due to its high slagging and bed agglomeration tendencies, the best use of wheat DDGS may be to mix it with other fuels, preferably with high Ca and Mg contents (e.g. woody biomass fuels), so that only a minor fraction of the total ash-forming elements is contributed by the wheat DDGS. Because of their high N- and S contents, RM and wheat DDGS require applications with flue-gas cleaning, economically viable at large-scale. Powder combustion of RM and wheat DDGS should be used with caution, as potassium phosphate particles have low melting temperatures and could therefore increase the risk of deposit formation. Use of HR in small-scale pellet appliances is an interesting option due to low emissions, low ash content and low slagging tendency. While most large-scale combustion uses of HR would be feasible, the low ash and alkali contents and stable powder combustion of HR may be better exploited in a combined-cycle process, as the alkali content can be kept sufficiently low for use in robustgas turbines, simplifying the gas cleaning.In the techno-economic assessment, residue (HR) was assumed to be combusted on site, to supply process steam and electricity to the liquid biofuel production (wood-based ethanol) with surplus residue either sold as solid fuel or used for additional heat and power generation. With a combined cycle to increase electricity production, a location with a large district heating base load is not needed. As electricity replaced is largely generated with fossil fuels, a combined cycle is significantly more effective as a climate mitigation measure than a steam-cycle only, with about 25 percent greater reduction in CO2 emissions per litre of ethanol produced. While it is generally accepted that energy use of the residue is important to the process economy and environmental benefits of ligno-cellulosic ethanol production, it can be concluded from this study that the choice of integrated process design has a significant impact on CO2 emissions.

  • 6.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Umeå universitet.
    Boström, Dan
    Umeå universitet.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Combustion and fuel characterisation of wheat distillers dried grain with solubles (DDGS) and possible combustion applications2012In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 102, p. 208-220Article in journal (Refereed)
    Abstract [en]

    The present transition to a sustainable global energy system requires that biomass is increasingly combusted for heat and power production. Agricultural fuels considered include alkali-rich fuels with high phosphorus content. One such fuel is wheat distiller’s dried grain with solubles (wheat DDGS) from wheat-based ethanol production. Further increases in ethanol production may saturate the current market for wheat DDGS as livestock feed, and fuel uses are therefore considered. Fuel properties of wheat DDGS have been determined. The ash content (5.4. ± 1.6 %wt d.s.) is similar to many agricultural fuels. In comparison to most other biomass fuels the sulphur content is high (0.538 ± 0.232 %wt d.s.), and so are the contents of nitrogen (5.1 ± 0.6 %wt d.s.), phosphorus (0.960. ± 0.073 %wt d.s.) and potassium (1.30 ± 0.35 %wt d.s.). To determine fuel-specific combustion properties, wheat DDGS and mixes between wheat DDGS and logging residues (LR 60 %wt d.s. and DDGS 40 %wt d.s.), and wheat straw (wheat straw 50 %wt d.s., DDGS 50 %wt d.s.) were pelletized and combusted in a bubbling fluidised bed combustor (5 kW) and in a pellets burner combustor (20 kW). Pure wheat DDGS powder was also combusted in a powder burner (150 kW). Wheat DDGS had a high bed agglomeration and slagging tendency compared to other biomass fuels, although these tendencies were significantly lower for the mixture with the Ca-rich LR, probably reflecting the higher first (solid) melting temperatures of K–Ca–Mg-phosphates compared to K-phosphates. Combustion and co-combustion of wheat DDGS resulted in relatively large emissions of fine particles (<1 μm) for all combustion appliances. For powder combustion PMtot was sixteen times higher than from softwood stem wood. While the Cl concentrations of the fine particles from the LR–wheat DDGS-mixture in fluidised bed combustion were lower than from combustion of pure LR, the Cl- and P-concentrations were considerably higher from the wheat DDGS mixtures combusted in the other appliances at higher fuel particle temperature. The particles from powder combustion of wheat DDGS contained mainly K, P, Cl, Na and S, and as KPO3 (i.e. the main phase identified with XRD) is known to have a low melting temperature, this suggests that powder combustion of wheat DDGS should be used with caution. The high slagging and bed agglomeration tendency of wheat DDGS, and the high emissions of fine particles rich in K, P and Cl from combustion at high temperature, mean that it is best used mixed with other fuels, preferably with high Ca and Mg contents, and in equipment where fuel particle temperatures during combustion are moderate, i.e. fluidised beds and possibly grate combustors rather than powder combustors.

  • 7. Eriksson, Gunnar
    et al.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Backman, Rainer
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Pettersson, Esbjörn
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Combustion characterization of rapeseed meal and possible combustion applications2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 8, p. 3930-3939Article in journal (Refereed)
    Abstract [en]

    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.

  • 8. Eriksson, Gunnar
    et al.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Pettersson, Esbjörn
    Pommer, Linda
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Lindström, Erica
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Backman, Rainer
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Öhman, Rikard
    Energy Technology Centre, Piteå.
    Förbränningskarakterisering av rapsmjöl och förslag till optimalt nyttjande i olika förbränningsanläggningar2007Report (Other academic)
    Abstract [en]

    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.

  • 9.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Jacobsson, Jan-Erik
    Mekanismer för spontan spridning av lönsam energieffektiv teknik1998Report (Other academic)
  • 10.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kjellström, Björn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Assessment of combined heat and power (CHP) integrated with wood-based ethanol production2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 12, p. 3632-3641Article in journal (Refereed)
    Abstract [en]

    A techno-economic assessment is made of wood-based production of ethanol, where the by-products are used for internal energy needs as well as for generation of electricity, district heat and pelletised fuel in different proportions for external use. Resulting ethanol production costs do not differ much between the options but a process where electricity generation is maximised by use of the solid residues as fuel for a combined cycle is found to give 20% more reduction of green-house gas emissions per liter of ethanol produced than the other options. Maximising electricity generation at the expense of district heat generation also allows more freedom when suitable sites for ethanol plants are looked for. Use of gasified biofuel for a combined cycle power plant is a demonstrated technology, however, the low ash and alkali content of the hydrolysis residue may allow direct combustion in the gas turbine topping cycle. This would reduce the necessary investment considerably. The potential advantages of using a combined cycle for maximising the electric power output from an energy combinate, producing ethanol and electricity from biomass, justifies further exploration of the possibilities for using hydrolysis residue directly as gas turbine fuel.

  • 11.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kjellström, Björn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Corrigendum to: Assessment of combined heat and power (CHP) integrated with wood-based ethanol production [Applied Energy 87 (12) (2010) 3632-3641]2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 5, p. 1997-1998Article in journal (Other academic)
  • 12. Eriksson, Gunnar
    et al.
    Kjellström, Björn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundqvist, Björn
    Paulrud, S.
    SLU, Umeå.
    Combustion of wood hydrolysis residue in a 150 kW powder burner2004In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 83, no 11-12, p. 1635-1641Article in journal (Refereed)
    Abstract [en]

    A combustion test has been made with residues from hydrolysis of wood for fuel ethanol production. A 150 kW powder burner was used. Fuel feeding and combustion were stable. The average concentration of CO in the stack gas was 8 mg/MJ, the average concentration of NOx was 59 mg/MJ and the average total hydrocarbon concentration was below 1 ppm, at an average O2-concentration of 4.6%. The low contents of potassium and sodium in the hydrolysis residue make the material attractive as a gas turbine fuel and the conclusion of this test is that direct combustion may be a feasible approach for gas turbine applications.

  • 13.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Nordgren, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Berg, Magnus
    Vattenfall Research & Development.
    New experimental characterisation methods for solid biomass fuels to be used in combined heat and power generation2008In: Proceedings: World Bioenergy 2008 : [Conference & Exhibition on Biomass for Energy, 27 - 29 May 2008, Jönköping - Sweden] / [ed] Johan Vinterbäck, Stockholm: Swedish Bioenergy Association (SVEBIO) , 2008, Vol. Poster sessions, p. 264-273Conference paper (Refereed)
    Abstract [en]

    The replacement of fossil fuels will lead to an increasing demand for unconventional biofuels. Fuel characterisation to predict combustion properties and facilitate the choice of combustion applications is important to avoid costly and time-consuming mistakes. Traditional methods are developed mainly for coal. Therefore procedures adapted specifically for solid biomass fuels are needed. This work is a survey on approaches for combustion characterisation of biomass developed during the last ten years. Innovative characterisation methods of interest concern: 1) Fuel handling behaviour: grindablility, erosion and abrasion properties. 2) Combustion characterisation: devolatilisation properties (important for ignition and flame stability), char burnout time. 3) Slagging and fouling properties of ash: ash particle formation, ash particle size distribution, ash composition, melting and gasification temperatures, slagging of bottom ash, reducing the risk by mixing with other fuels or using fuel additives and choice of suitable combustion applications for specific fuels. The main conclusions are: 1) a method to measure grindability which takes electric power consumption into account is needed as the Hardgrove Grindability Index used for coal grinding is pointless for biofuels, 2) there is a need to develop convenient low-cost methods to measure slagging and fouling tendencies, devolatilisation kinetcs and char burnout for high heating rates found in fluidised beds and powder burners.

  • 14.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Tiberg, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Klarar Luleå miljömålen?: utsläpp av koldioxid och klimatskydd i Luleå kommun1995Report (Other academic)
  • 15.
    Eriksson, Gunnar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Tiberg, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Delin, Staffan
    Luleå tekniska universitet.
    Fysisk redovisning för Norrbottens län och två perspektiv på bärkraftig utveckling1996Report (Other academic)
  • 16.
    Grimm, Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Umeå universitet.
    Eriksson, Gunnar
    Boström, Dan
    Umeå universitet.
    Boman, Christoffer
    Umeå universitet.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Effekter av fosfortillsats vid förbränning av biomassa2010Report (Other academic)
    Abstract [sv]

    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.

  • 17.
    Hermansson, Roger
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Eriksson, Gunnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Increased combustion stability in modulating biomass boilers for district heating systems2002Report (Other academic)
    Abstract [en]

    One of the problems in small district heating systems is the large load variation that must be handled by the system. If the boiler is designed to cover the needs during the coldest day in winter time in northern Europe it would have to run at loads as low as 10% of full load during summer time, when heat is needed only for tap water production. Load variations in small networks are quite fast and earlier investigations have shown that existing biomass boilers give rise to large amounts of harmful emissions at fast load variations and at low loads. The problem has been addressed in different ways: Three new boiler concepts have been realized and tested: A prototype of a 500 kW boiler with partitioned primary combustion chamber and supplied with a water heat store. A 10 kW bench scale combustor and a 500 kW prototype boiler based on pulsating combustion. Bench scale boilers to test the influence from applied sound on emissions and a 150 kW prototype boiler with a two-stage secondary vortex combustion chamber. Development of control and regulating equipment: Glow Guard, a control system using infra-red sensors to detect glowing char on the grate, has been constructed and tested. A fast prediction model that can be used in control systems has been developed. Simulation of the combustion process: Code to simulate pyrolysis/gasification of fuel on the grate has been developed. Combustion of the gas phase inside the combustion chamber has been simulated. The two models have been combined to describe the combustion process inside the primary chamber of a prototype boiler. A fast simulation code based on statistical methods that can predict the environmental performance of boilers has been developed. One of the boiler concepts matches the desired load span from 10 to 100% of full load with emissions far below the set limits for CO and THC and close to the set limits for NO{sub x}. The other boilers had a bit more narrow load range, one with very low emissions except for NO{sub x} and the other with emissions close to the set limits. The Glow Guard worked as desired and will be a useful tool for control of combustion on the grate. The simulation of the processes inside the combustion chamber matches the experimental results well in terms of velocity and temperature. Species concentration were reasonable well described at the exit from the combustion chamber but were poorly described above the fuel bed. The dynamic model based on statistics is capable of reproducing the over-all dynamic behaviour of biofuel-fired boilers.

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