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  • 1.
    Binti Munajat, Nur Farizan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Correlation of laminar flame speed and lean blowoff limit with the fuel composition of gasified biomassIn: Fuel, ISSN 0016-2361, E-ISSN 1873-7153Article in journal (Other academic)
    Abstract [en]

    The composition of the product gas produced from a biomass gasification process varies largely depending on several operational factors. The present study gathers the combustion information of different fuel mixtures that resemble the wide range of product gases from biomass gasification process. Two combustion parameters that are laminar flame speed, SL and lean blowoff limit, ERblowoff have been studied as functions of the content of H2 in the fuel mixture as well as the ratios of CO/H2, hydrocarbons/H2 and diluents/H2. From the plotted graphs, mathematical correlations between the parameter studied and the component of the gas mixture have been derived. The equations developed can be used to calculate the laminar flame speed and blowoff equivalent ratio for a wide range of gasified biomass. The graphs show that the H2 content and diluents/H2 ratio have the greatest influence on the laminar flame speed of the gas mixture and higher effect compared to the influence by the ratio of CO/H2 and hydrocarbons/H2. For the lean blowoff limit, the descending order of influence is the ratio of diluents/H2, H2 content and the ratio of CO/H2. While no importance on the lean blowoff limit is observed for the ratio of hydrocarbons/H2.

  • 2.
    Binti Munajat, Nur Farizan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Influence of water vapour and tar compound on combustion of simulated gasified biomassIn: Fuel, ISSN 0016-2361, E-ISSN 1873-7153Article in journal (Other academic)
    Abstract [en]

    Gasification is a thermo‐chemical process which converts biomass fuel into a gaseous mixture, gasified biomass, which can be used in various prime movers. For heat and power generation, using gasified biomass in a combustion device, for example, can give lower undesired emission compared to direct combustion of solid biomass. However, with regards to its variety in composition and lower heating value, the combustion behaviour of gasified biomass may differ from natural gas. The main objective of this study is to investigate the influence of water and tar compound on the combustion of simulated gasified biomass, which mainly contains CO, H2, CH4, CO2, N2. The combustion tests are conducted at atmospheric pressure in a premixed combustor. At a fixed input thermal load, CO and NOx emission levels, combustion temperature, and blowoff characteristics of gasified biomass are observed while varying the volume fraction of water (H2O) or benzene (C6H6) vapours in the fuel mixture. With low H2O level in the fuel mixture, the combustion temperature is almost constant, while NOx emission is decreased compared to dry gasified biomass. On the contrary, the combustion temperature decreases and NOx emission is almost constant at higher H2O content. A temperature limit was observed where CO emission could be maintained at low concentration. The blowoff limit was shifted to higher equivalence ratio. The blowoff temperature was first slightly decreased at lower H2O level and raised when H2O level is further increased. With the content of C6H6, the combustion temperature and NOx emission enhanced, while CO emission was reduced. The blowoff occurs at slightly higher equivalence ratio and temperature compared to gasified biomass without C6H6. The study shows that the presence of H2O and C6H6 in gasified biomass may give positive effects on the emission characteristics during combustion, but also that there are limits for these effects.

  • 3.
    Binti Munajat, Nur Farizan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Temperature, emission and lean blowoff limit of simulated gasified biomass in a premixed combustorIn: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118Article in journal (Other academic)
    Abstract [en]

    Biomass can be converted to a gaseous fuel through gasification in order to be used in higher efficiency conversion. Combustion of gasified biomass gas (GBG) in gas turbines, for example, potentially reduces the CO2 emission compared to natural gas and diminishes the dependence of fossil fuels. However, the wide variety in the gas composition and its lower heating value will affect the subsequent combustion process with respect to emission levels and flame stability. In this study, premixed combustion of simulated GBG is investigated experimentally at atmospheric pressure and compared with pure CH4 (simulated natural gas). Combustion performance in terms of emission levels and blowoff is observed. The GBG fuel with noncombustible to combustible components ratio of 1.5 is tested in comparison with pure CH4 at fixed input thermal load. The GBG fuel consists of a mixture of CO/H2/CH4/CO2/N2and its proportion reassembles the mixture from air‐blown gasification. The high diluent content decreases the lower heating value (LHV) and increases the volumetric flow compared to CH4. As a result, lower combustion temperature and different flame region than CH4were found in the combustor. However, the GBG combustion still can be stabilized at lower temperature and leaner condition compared to CH4 while maintaining low CO and NOx emissions. As low as ~15 ppm and ~5ppm of CO and NOxemissions, respectively, could be achieved at an equivalence ratio equal to 0.5. It was found that at a combustion temperature below ~800oC, both CO and UHC start to rise from their stable and low concentration. At different input thermal loads, a shift in the optimum operating condition for the GBG combustion was found. No auto‐ignition or flashback events were found during the combustion of GBG in all experiment conditions tested. The results show the possibility to use both GBG and natural gas in one and the same combustor without compromising low emission levels.

  • 4.
    Birru, Eyerusalem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Beyene, Getachew
    Addis Ababa University, Ethiopia.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Assessing the potential of energy saving in a traditional sugar canemill during steady state and transient conditions: part I: basecase plant model2015In: Biomass Conversion and Biorefinery, ISSN 2190-6823Article in journal (Refereed)
    Abstract [en]

    Sugar cane mills are energy intensive industries andalso have a large potential of providing surplus energy interms of heat or power. Identification of heat and mechanicallosses in sugar mills is one approach in indicating energysaving potential in sugar mills, especially in traditional mills.Such assessment of the energy flows in sugar mills needs to bedone both in steady state and transient conditions (where suddenstoppages occur). In this paper, such an approach is consideredwhere a base case plant is modeled for steady state andtransient state operations. For the transient state study, a typicalstoppage is chosen and three different scenarios aremodeled. Heat loss calculations are done for major cogenerationunits and for the amount accumulated of the surplus bagassewhen the steady state operation is estimated. The resultsof the models show that during steady state operation, thelosses related to mechanical prime movers is on the higherside as the mills and shredder are driven by steamand generatemechanical power higher than what is needed by the mills andthe shredder equipment themselves. In the transient statescenarios, where fuel oil is introduced during press mill stoppage,there is steam wasted (steam that could have been usedfor mechanical power generation) starting from the periodwhere the fuel oil is introduced until the power required duringthe stoppage is reached. The CO2 emission during the use offuel oil is also quite significant during the stoppage.

  • 5.
    Birru, Eyerusalem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Beyene, Getachew
    Addis Ababa University, Ethiopia.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Upgrading of a traditional sugar cane mill to a modern milland assessing the potential of energy saving during steady stateand transient conditions: part II: models for a modifiedcogeneration unit2016In: Biomass Conversion and Biorefinery, ISSN 2190-6823, Vol. 6, no 2, p. 233-245Article in journal (Refereed)
    Abstract [en]

    It is known that there is a significant amount ofthermal energy used for the sugar cane industry for the purposeof power production and for use in the sugar or ethanolprocessing in cane sugar industries. Likewise, it is understoodthat there are substantial amounts of waste heat that is notbeing recovered, in particular for traditional sugar mills. Regardlessof this, energy conservation is given less considerationas compared to operational convenience due to the factthat sugar mills are self-sufficient in energy (heat and power).The identification of such potential heat loss areas (especiallyduring transient conditions) suggests the sugar mills play avital role in energy saving. In this study, a modified setup ofthe base case plant considered in part I of this paper is assessedfor its energy potential and possible major heat losses duringsteady state and transient conditions where 2-h stoppage of themill presses are considered to occur. For the modified setup,there are two major scenarios considered having two subscenarioseach. The result of the assessment showed that thesteady state assumption scenario of the modified plant (wherebagasse drying is not considered) indicated a 20 % reductionin the losses considered which resulted in a 57 % power generationincrease as compared to the steady state model of thebase case plant. It is also possible to save excess bagasse bydrying the bagasse for later use during unexpected stoppage.The carbon dioxide emission (amounting 29 t/day in case 2aof this study) that occurs during the use of fuel oil during suchstoppages will thus be avoided. The simple economic analysisshowed that it is only in case 2a where fuel oil cost is includedin the operation cost that resulted in a negative NPV. Since therest of the scenarios use bagasse as a fuel which is free, theNPV for all was positive. For the electricity price of 0.04 US$/kWh and discount rate of 15 %, the minimum paybackperiod attained is about 3 years (case 1b) where the bagassemoisture content is 30 % whereas the maximum payback periodis 6 years (case 1a) where there is no bagasse dryingconsidered.

  • 6.
    Birru, Eyerusalem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Herrera, Idalberto
    University “Marta Abreu” of Las Villas (UCLV), Cuba.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Feychting, Sofia
    KTH, School of Industrial Engineering and Management (ITM).
    Vitez, Marina
    KTH, School of Industrial Engineering and Management (ITM).
    Abdulhadi, Emma Bednarcik
    KTH, School of Industrial Engineering and Management (ITM).
    Larsson, Anna
    KTH, School of Industrial Engineering and Management (ITM).
    Onoszko, Emanuel
    KTH, School of Industrial Engineering and Management (ITM).
    Hallersbo, Mattias
    KTH, School of Industrial Engineering and Management (ITM).
    Weilenmann, Louise
    KTH, School of Industrial Engineering and Management (ITM).
    Puskoriute, Laura
    KTH, School of Industrial Engineering and Management (ITM).
    A Comparison of Various Technological Options for Improving Energy and Water Use Efficiency in a Traditional Sugar Mill2016In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 8, no 12, article id 1227Article in journal (Refereed)
    Abstract [en]

    This study is a comparison of four technological improvements proposed in previous works for the Cuban sugar mill Carlos Balino. These technological options are: (1) utilization of excess wastewater for enhanced imbibition; (2) utilization of waste heat for thermally driven cooling; (3) utilization of excess bagasse for pellets; and (4) modification of the cogeneration unit for maximum electric power generation. The method used for the evaluation of the technological options involves using criteria such as energy saving, financial gains, and CO2 emission saving potential. The results of the analysis show that the first three technological improvement options are attractive only during the crushing season. On the other hand, the last technological improvement option can be attractive if a year round generation of surplus power is sought. The first technological improvement option leads to only minor changes in energy utilization, but the increase in sugar yield of 8.7% leads to attractive profitability with an extremely low payback period. The CO2 emissions saved due to the fourth technological improvement option are the highest (22,000 tonnes/year) and the cost of CO2 emissions saved for the third technological improvement option (lowest) amount to 41 USD/tonne of CO2 emissions saved. The cycle efficiencies of the third and fourth technological improvement options are 37.9% and 36.8%, respectively, with payback periods of 2.3 and 1.6 years. The second technological improvement option is the least attractive alternative of the group.

  • 7.
    Birru, Eyerusalem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Energy performance comparisons and enhancements in the sugar cane industry2019In: Biomass Conversion and Biorefinery, ISSN 2190-6815, E-ISSN 2190-6823, Vol. 9, no 2, p. 267-282Article in journal (Refereed)
    Abstract [en]

    In this study, energy-related operational parameters for modern and traditional (conventional) sugar mills are analyzed, with the goals of identifying improvements in energy efficiency and potential for surplus electricity export. Results show that the power- to-heat ratio of modern and traditional mills is clearly distinct, lying in the ranges of 0.3–0.5 and 0.04–0.07, respectively. Modifications under consideration for the traditional mills include the following upgrades: electric drives and higher capacity back-pressure turbine (case 1); high-pressure boiler, condensing extraction steam turbine and electric drives (case 2); and improvements in case 2 plus bagasse drying (case 3). The thermodynamic impact of these modifications shows that more power is generated as the modification becomes more advanced. Case 1 exhibits a modest increase in cogeneration efficiency (4%) as compared to the base case, while the cogeneration efficiency increase is more marked for cases 2 and 3 (21% and 31%, respectively). Surplus power was studied in a regional context, where it was found that the contribution of 19 retrofitted sugar mills in nine Brazilian regions could supply 30% or more power as compared to current installed power capacity. The economic analysis showed that levelized cost of electricity (LCOE) was lowest for case 1 (11 USD/MWh) and highest for cases 2 and 3 (58 USD/kWh).

  • 8.
    Cardozo, Evelyn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal power analysis of flue gases during the combustion of agricultural residues in a residential pellet boilerManuscript (preprint) (Other academic)
  • 9.
    Cardozo, Evelyn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    An experimental study of a Stirling engine micro-CHP system fuelled on wood and sugarcane bagasse pelletsManuscript (preprint) (Other academic)
  • 10.
    Cardozo, Evelyn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Universidad Mayor de San Simón, Bolivia .
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Integration of a wood pellet burner and a Stirling engine to produce residential heat and power2014In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 73, no 1, p. 669-678Article in journal (Refereed)
    Abstract [en]

    The integration a Stirling engine with a pellet burner is a promising alternative to produce heat and power for residential use. In this context, this study is focused on the experimental evaluation of the integration of a 20 kWth wood pellet burner and a 1 kWe Stirling engine. The thermal power not absorbed by the engine is used to produce hot water. The evaluation highlights the effects of pellet type, combustion chamber length and cycling operation on the Stirling engine temperatures and thermal power absorbed. The results show that the position of the Stirling engine is highly relevant in order to utilize as much as possible of the radiative heat from the burner. Within this study, only a 5 cm distance change between the Stirling engine and the pellet burner could result in an increase of almost 100 °C in the hot side of the engine. However, at a larger distance, the temperature of the hot side is almost unchanged suggesting dominating convective heat transfer from the hot flue gas. Ash accumulation decreases the temperature of the hot side of the engine after some cycles of operation when a commercial pellet burner is integrated. The temperature ratio, which is the relation between the minimum and maximum temperatures of the engine, decreases when using Ø8 mm wood pellets in comparison to Ø6 mm pellets due to higher measured temperatures on the hot side of the engine. Therefore, the amount of heat supplied to the engine is increased for Ø8 mm wood pellets. The effectiveness of the engine regenerator is increased at higher pressures. The relation between temperature of the hot side end and thermal power absorbed by the Stirling engine is nearly linear between 500 °C and 660 °C. Higher pressure inside the Stirling engine has a positive effect on the thermal power output. Both the chemical and thermal losses increase somewhat when integrating a Stirling engine in comparison to a stand-alone boiler for only heat production. The overall efficiency of the pellets fired Stirling engine system reached 72%.

  • 11.
    Cardozo Rocabado, Evelyn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Facultad de Ciencias y Tecnología (FCyT), Universidad Mayor de San Simon (UMSS), Cochabamba, Bolivia.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Alejo, Lucio
    Universidad Mayor de San Simon.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Combustion of agricultural residues: An experimental study for small-scale applications2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 115, p. 778-787Article in journal (Refereed)
    Abstract [en]

    Energy services could be greatly improved by using of residues from local food industries in small-scale combustion units. Wood pellets are a reliant and proven fuel to be used in small-scale combustion units. However, these units should preferably be able to use different types of biomass depending what it is locally available. Therefore, studies have been focused on exploring the suitability of using agricultural residues for small-scale heat and power generation using direct combustion. This study targets to compare the combustion of different agricultural residues in a single unit designed for wood pellets. The different biomass fuels used are circle divide 6 mm and circle divide 8 mmwood pellets, circle divide 6 mmbagasse pellets, circle divide 6 mmsunflower husk (SFH) pellets and Brazil nut (BN) shells. The results reveal a decrease in the fuel power input, higher oxygen levels in the flue gases and shorter cycles for ash removal when using the agricultural residues. The excess air ratio was calculated based on a mass balance and compared with a standard equation showing a good agreement. CO and NO emission levels as well as the relative conversion of fuel-C to CO were higher for the BN shells and SFH pellets in comparison to the other biomass types. SO2 emission was estimated based on the analysis of unburned sulfur in ash and mass balances; the higher estimated levels corresponded to the BN shells and SFH pellets. All the biomass sorts presented over 95% relative conversion of fuel-C to CO2. Wood pellets and BN shells presented the highest amount of unburned carbon in ash relative to the fuel-C. The relative conversion of fuel-N to NO and fuel-S to SO2 were higher for wood pellets. Bagasse pellets showed similar emission levels and relative conversion efficiency to wood pellets.

  • 12.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Comparative study of residue pellets from cane sugar and palm-oil industries with commercial wood pellets, applied in downdraft gasification2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    While biomass utilization for energy conversion in the industrialized nations is being largely developed, highly efficient and environmentally friendly, many tropical countries still use biomass at low efficiencies and high emission levels. The main reasons for these gaps are both political and technological: the energy markets are different, the Gross National Product (GDP) differs widely, and the feedstock differs in form and conversion behaviour. By implementing newer technologies adapted for tropical biomass feedstock, there would be a large potential in these countries for increased energy services since access to modern energy still is an essential step for improving the GDP for a country. Two dominant and tropically placed industries available for energy improvements are the cane sugar and palm-oil industries, which both produce an abundant amount of biomass residues. One step towards enhanced utilization of the residues, which would not require large investment costs in the power plant section nor in the processes of these industries, would be to install a pelletizing unit in the industry area to make fuel out of the excess residues for sale to the nearby villages. The pellets could be used both for cooking/heating and for small-scale power generation in a gasification-IC engine plant.

    The overall objective of this study is to experimentally evaluate the biomass residues in pellet form from the cane sugar and palm oil industries during conversion to useful energy in small-scale systems.

    The thesis is built upon five publications which include experimental analysis on flaming pyrolysis and rapid heating of pellets (paper I), pyrolysis in oxygen-free atmosphere and slow heating with subsequent steam gasification (paper II), global pelletizing data such as relative energy consumption, temperature levels, particle size and moisture content for successful pelletizing process (paper III), downdraft gasification evaluation including reactor temperature distribution, gas composition, cold-gas efficiency and packed-bed mechanics (paper IV) and a numerical model including the overall system efficiency for residue-to-electric power based in a small-scale gasifier system (paper V).The single-pellet studies revealed that pyrolysis in reducing atmosphere is to prefer compared to flaming pyrolysis in oxidizing environment with regards to the char quality.

    The studies also showed favourable thermochemical and mechanical behaviour for smaller size pellets (Ø6- Ø8mm) compared to larger size ones (Ø12 mm). Therefore, a downdraft gasifier of closed constricted type was designed for real gasification tests of the residue pellets of sizes Ø6- Ø8mm. These tests showed that all the studied pellet sorts could be used in one and the same gasifier, resulting in different reactor temperature distributions and gas compositions with lower heating values in the range of 4.1-5.4 MJ/m3n dry gas. The reactor bed dynamics showed to be dependent both on the fuel reactivity and the size, with less pressure drop for larger size pellets with lower reactivity. The pelletizing process itself revealed that the selected residues all needed higher moisture content and smaller particle size than recommended for wood for successful pelletizing. The relative electric energy consumption was lower when producing larger size pellets Ø8 mm than smaller ones (Ø6 mm) of same material. For untreated wet empty-fruit bunch (EFB) a stand-alone power plant with integrated EFB pre-treatment and gasification could generate 380 kWh of net electricity per ton of EFB at a “well-to-wheel” efficiency of 15%.

  • 13.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Conversion of palm-oil empty fruit bunch to electricity via milling, pelletizing and gasification: Short communication2009Report (Other academic)
  • 14.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thermochemical conversion of biomass pellets: a parametric study for application in downdraft gasification2005Licentiate thesis, comprehensive summary (Other scientific)
  • 15.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Björnbom, Emilia
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Bolado, David
    Giner, Marian
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pyrolysis and gasification of pellets from sugar cane bagasse and wood2006In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 85, no 10-11, p. 1535-1540Article in journal (Refereed)
    Abstract [en]

    Wood pellets have become a popular form of biomass for power generation and residential heating due to easier handling both for transportation and for feeders in the treatment units, improved conversion and storage possibilities. The research on wood pellets as fuel has also been intensified during the past decade. However, other biomass sorts in pellet form, such as sugar cane bagasse, have not yet been extensively studied, especially not physical effects on the pellets during thermal treatment. Bagasse and wood pellets of different origin and sizes, shredded bagasse and wood chips have been studied in a thermogravimetric equipment to compare the effects of sort, origin, size and form of biomass during slow pyrolysis and steam gasification. Physical parameters such as decrease of volume and mass during treatment, as well as pyrolysis and gasification rates are of primary interest in the study. An important observation from the study is that for pellets the char density decreased during pyrolysis to a minimum around 450 degrees C, but thereafter increased with continued heating. The wood chips behaved differently with a continuous char density decrease during pyrolysis. Another conclusion from the work is that the size of the pellet has larger impact on the shrinkage behaviour throughout the conversion than the raw material, which the pellet is made of.

  • 16.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Downdraft gasification of pellets made of wood, palm-oil residues respective bagasse: Experimental study2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 3, p. 899-908Article in journal (Refereed)
    Abstract [en]

    The downdraft gasification technology has an increased interest among researchers worldwide due to the possibility to produce mechanical and electrical power from biomass in small-scale to an affordable price. The research is generally focused on improvement of the performance and optimizing of a certain gasifier, on testing different fuels, on increasing the user-friendliness of the gasifier and on finding other uses for the product gas than in an IC-engine, for example liquid fuel production.

    The main objective with the gasification tests presented here is to further contribute in the field by studying the impact of the char bed properties such as char bed porosity and pressure drop on the gasification performance as well as the impact of fuel particle size and composition on the gasification process in one and the same gasifier. In addition, there is very little gasification data available in literature of “before disregarded” fuels such as sugar cane bagasse from sugar/alcohol production and empty fruit bunch (EFB) from the palm-oil production. By pelletizing these residues, it is possible to introduce them into downdraft gasification technology which has been done in this study.

    The results show that one and the same reactor can be used for a variety of fuels in pellet form, but at varying air–fuel ratios, temperature levels, gas compositions and lower heating values. Gasification of wood pellets results in a richer producer gas while EFB pellets give a poorer one with higher contents of non-combustible compounds. In this gasification study, there is almost linear relation between the air–fuel ratio and the cold-gas efficiency for the studied fuels: Higher air–fuel ratios result in better efficiency. The pressure drop in the char bed is higher for more reactive fuels, which in turn is caused by low porosity char beds.

  • 17.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Gomez, M
    Hedman, H
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Milling and pelletizing residues from cane sugar and palm oil industries: Physical parameters and electrical energy consumption2009Other (Other academic)
  • 18.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Salomon Popa, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    An Extensive Technical, Economical and Environmental Assessment of Energy Recovery from Palm-Oil Residues: SWE-2005-3862009Report (Other academic)
    Abstract [en]

    The Dept. of Energy Technology at KTH, together with Universidad Autónoma de Bucaramanga, Colombia, studied the different possibilities for increasing the usage of palm oil residues for energy production in an optimized way. The main purpose was to maximize the use of the solid residues coming from palm oil extraction, substitute fossil fuels in cooking, reduce emissions and environmental impacts and improve the social/economic conditions of the region. The emphasis was in introducing the discarded solid residues – EFB - as a fuel and the effective use of fibres and shells. The study was based on several innovative and unique approaches that include the pelletization of EFB for gasification purposes, densification of fibres and shells for their use in different energy applications, anaerobic digestion of EFB for biogas production and a complete optimization of the energy system considering efficiency, technology availability, environmental issues and economic factors.

  • 19.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Öhman, Marcus
    Umeå Universitet.
    Björnbom, Emilia
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermochemical characteristics of sugar cane bagasse pellets2005In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 84, no 5, p. 569-575Article in journal (Refereed)
    Abstract [en]

    Pelletisation facilitates utilisation of sugar cane bagasse as a fuel and storage for year-round electricity generation. The present work determines thermochemical characteristics of bagasse pellets of different sizes and origins, using various temperatures (600, 750 and 900 degrees C) and gas flow rates (4, 7 and 10 L/min) with varying concentrations of oxygen (5, 10 and 15 %) in mixtures with nitrogen. Of major interest are the effects of raw material, origin and size of pellets, and the treatment conditions on the rate of pyrolysis and the structure and reactivity of char in combustion. The char yield of the larger pellets of high-ash content bagasse was practically independent of treatment conditions. Smaller pellets gave better mechanical stability of the char but lower reactivity.

  • 20. Lovella, Y. G.
    et al.
    Herrera, I.
    De Paepe, W.
    Contino, F.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Crero, M. M.
    Pinzi, S.
    Del Pil Dorado, M.
    Multi-objective optimization of the thermal and hydraulic design of a heat exchanger of the type shell and tubes2015In: ECOS 2015 - 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems , 2015Conference paper (Refereed)
    Abstract [en]

    The extensive use of heat exchangers in the industry makes its optimization be crucial for raising efficiency and energy conservation. In the context of cleaner production and energy sustainability of the industrial sector, energy efficiency is a cornerstone to reduce fuel consumption. In this way the performance of the heat exchanger is a key factor. This work aims to contribute to energy efficiency, for this purpose a multi-objective optimization of the thermal and hydraulic design of heat exchangers of shell and tubes is implemented. A meta-heuristic technic of genetic algorithm, using two fitness functions, number of entransy dissipation and total cost was programed. Finally it is obtained the Peto front with multiple solutions, these solutions where adjusted to the operating conditions.

  • 21.
    Munajat, Nur Farizan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fakhrai, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Influence of water vapour and tar compound on laminar flame speed of gasified biomass gas2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 98, p. 114-121Article in journal (Refereed)
    Abstract [en]

    Biomass can be converted to a gaseous fuel through gasification in order to be used in higher efficiency conversion equipment. Combustion of a gaseous fuel generally allows for higher combustion temperatures than that of a solid fuel leading to the higher efficiency. However, the gasified biomass gas (GBG) contains condensable compounds, such as water vapour and tars, which both will affect the subsequent combustion process with respect to emission levels and flame stability. Cleaning of the GBG prior to combustion is very costly and therefore further research is needed on direct combustion of GBG containing these condensable compounds, in order to develop stable combustion techniques for GBG. The laminar flame speed is a main parameter that relates to other important flame properties such as stability, extinction limit and flashback. Each of GBG components have different chemical and transport properties, which then influences the laminar flame speed of GBG. In this study, the individual effect of water vapour (H2O) and tar compound addition in simulated GBG on laminar flame speed is investigated at atmospheric pressure. The tar compound used is benzene (C6H6) and simulated GBG used is CO/H-2/CH4/CO2/N-2 mixture. Experiments were carried out with conical burner stabilized flame and a Schlieren photography system. The volume fraction of additives in the fuel mixture was varied: for H2O from 0% to 5% and for C6H6 from 0% to 10%. The unburned fuel air mixture was preheated and the temperature was maintained at T-i = 398 K to avoid condensation of the liquid. It was found that measured laminar flame speed of GBG-air mixture decreases with addition of H2O in the fuel mixture. While, non-monotonic behaviour is shown with addition of C6H6. Initially, as the volume fraction of C6H6 incremented, the laminar flame speed decreases, reaching a minimum value, and then increase.

  • 22.
    Salomon, Marianne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gómez, Maria F.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Erlich, Catharina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pelletization: an alternative for polygeneration in the palm oil industry2013In: Biomass Conversion and Biorefinery, ISSN 2190-6815, Vol. 3, no 3, p. 213-229Article in journal (Refereed)
    Abstract [en]

    Agricultural residues continue to attract interest for energy recovery purposes as a renewable, CO2 neutral and increasingly cost-competitive alternative to traditional fossil fuels. Furthermore, some of these residues, like palm oil residues, represent a disposal problem for the processing industries, or they are not used efficiently. Several palm oil mills (POM) lack efficient energy systems and thus there is a considerable potential for improvement. These factors represent a strong driving force for the development of innovative polygeneration plants with combined electricity, heat and refined fuel production based on conversion of solid residues. This paper aims at analyzing the use of agro-industrial residues as fuel. For that, we propose different technology configurations based on the case of a small-scale palm oil mill in Colombia processing 30 tons of fresh fruit bunch per hour. The technology configurations include steam cycles using backpressure turbines, condensing-extraction turbines and also gasification-gas engine cycles in hybrid configurations. The possibilities to produce pellets from the residues from palm oil were also analyzed. The steam cycle base operational parameters were 20 bar and 350 °C. However, more advanced steam conditions (40 bar) were also considered and evaluated. All the analyses performed included a maximum of 60 % of the empty fruit bunch (EFB) produced in the POM for energy purposes due to its value as natural fertilizer in the palm oil plantations. The results show that the POM under study and other POMs that use electricity from the national grid have the capacity of being self-sufficient to cover of all their energy needs using the solid residues available. This means that POMs that currently only generate the required heat for the process can generate the electricity required and in some cases even an excess of energy that could be sold to other users with an adequate use of the residues available. Furthermore, based on the modeling done in Aspen Utilities Planner® it is shown that it is possible to cover the demand of the POM, the required energy demand for EFB preparation included possible pelletization of these residues and even generate an excess of electricity. In several of the configurations, excess electricity generation could be achieved in the range of 0.5–8 MW.

1 - 22 of 22
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