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  • 151.
    Mousavi Takami, Kourosh
    et al.
    Mälardalen University, Department of Public Technology.
    Mahmoudi, Jafar
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Lindenmo, Magnus
    Surahammars Bruks AB, R&D.
    Evaluation of magnetic aging in transformers and electrical machines cores during operation: Modelling2009In: Proceedings of the Scientific Conference on Energy and IT at Älvsjö fair, Stockholm March 11-12, 2009 in connection with the “Energitinget 2009, 2009, p. 218-232Conference paper (Refereed)
    Abstract [en]

    Electric steels are processed to avoid the phenomenon known as magnetic aging. Non-oriented electrical steels are mostly used in rotating electrical machines and oriented steels used in transformers, which during operation generates heat. This could cause carbide precipitation/coalescence in the metallic matrix, impairing the magnetic properties of the steel, called magnetic aging. The steel has to contain very little carbon to avoid aging. This is achieved during the making of the steel or by a decarburising annealing of the final thickness strip or of the stamped laminations.

    The magnetic material for cores of a transformer and electrical machines should be characterised by high permeability and low energy losses in changing magnetic flux.

    In order to test that the magnetic properties do not become worse during these working conditions, the steel can be tested for magnetic ageing. The European standard defines the test cycle as 225°C for 24 hours. The American ASTM standard suggests two different cycles: 100 hours at 150°C or 600 hours at 100 °C.

     

    A test the losses after a heat treatment of 150°C f or 10 days for coils with higher carbon content than 26 ppm of the final product has performed here. This longer cycle has proved to give larger increases in the loss than the shorter one according to the European standard.

    The ageing process was much faster for a higher carbon content slab with 90 ppm C than for a lower one with 30 ppm C.

    ANN method using LMS has performed to aging real time identification. Results showed a 97% best fit. It showed that using ANN can predict the aging and a modern advanced relay can control the loading and temperature of electrical equipments to prevent of harmful damages.

  • 152.
    Naqvi, M.
    et al.
    KTH.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Energy conversion performance of black liquor gasification to hydrogen production using direct causticization with CO2 capture2012In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 110, p. 637-644Article in journal (Refereed)
    Abstract [en]

    This paper estimates potential hydrogen production via dry black liquor gasification system with direct causticization integrated with a reference pulp mill. The advantage of using direct causticization is elimination of energy intensive lime kiln. Pressure swing adsorption is integrated in the carbon capture process for hydrogen upgrading. The energy conversion performance of the integrated system is compared with other bio-fuel alternatives and evaluated based on system performance indicators. The results indicated a significant hydrogen production potential (about 141 MW) with an energy ratio of about 0.74 from the reference black liquor capacity (about 243.5 MW) and extra biomass import (about 50 MW) to compensate total energy deficit. About 867,000 tonnes of CO2 abatement per year is estimated i.e. combining CO2 capture and CO2 offset from hydrogen replacing motor gasoline. The hydrogen production offers a substantial motor fuel replacement especially in regions with large pulp and paper industry e.g. about 63% of domestic gasoline replacement in Sweden. (C) 2012 Elsevier Ltd. All rights reserved.

  • 153.
    Naqvi, M.
    et al.
    KTH.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Synthetic natural gas (SNG) production at pulp mills from a circulating fluidized bed black liquor gasification process with direct causticization2010In: Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010, 2010, p. 83-91Conference paper (Refereed)
    Abstract [en]

    Synthetic natural gas (SNG) production from black liquor gasification (BLG) replacing conventional recovery cycle at chemical pulp mills is an attractive option to reduce CO2 emissions and replace fossil natural gas. This paper evaluates the potential of SNG production from a circulating fluidized bed BLG process with direct causticization by investigating synthesis gas composition, purity requirements for SNG and process integration with the reference pulp mill producing 1000 air dried tonnes (ADt) of pulp per day. The objective of this study is to estimate the integrated process efficiency from black liquor (BL) conversion to SNG and to quantify the differences in overall process efficiencies of various bio-refinery options. The models include a BLG Island including BL gasifier, synthesis gas cooling and cleaning unit, methanation with SNG upgrading and a power boiler. The result indicates a large potential of SNG production from BL but at a cost of additional biomass import to compensate energy deficit in terms of BL conversion to SNG. In addition, the study shows a significant CO2 abatement when CO2 capture is carried out in SNG upgrading and also reducing CO2 emissions when SNG potentially replaces fossil natural gas.

  • 154.
    Naqvi, M.
    et al.
    Royal Institute of Technology (KTH).
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    System analysis of dry black liquor gasification based synthetic gas production comparing oxygen and air blown gasification systems2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 1275-1282Article in journal (Refereed)
    Abstract [en]

    The black liquor gasification based bio-fuel production at chemical pulp mill is an attractive option to replace conventional recovery boilers increasing system energy efficiency. The present paper studies circulating fluidized bed system with direct causticization using TiO2 for the gasification of the black liquor to the synthesis gas. The advantage of using direct causticization is the elimination of energy-intensive lime kiln which is an integral part of the conventional black liquor recovery system. The study evaluates the effects of gasifying medium i.e. oxygen or air, on the fluidized bed gasification system, the synthesis gas composition, and the downstream processes for the synthesis gas conversion to the synthetic natural gas (SNG). The results showed higher synthetic natural gas production potential with about 10% higher energy efficiency using oxygen blown gasification system than the air blown system. From the pulp mill integration perspective, the material and energy balance results in better integration of air blown system than the oxygen blown system, e.g. less steam required to be generated in the power boiler, less electricity import, and less additional biomass requirement. However, the air blown system still requires a significant amount of energy in terms of the synthesis gas handling and gas upgrading using the nitrogen rejection system.

  • 155.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Business feasibility of distributed off-grid electricity generation using mixed biomass compost: A scenario-based study2016Conference paper (Refereed)
  • 156.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nizami, A. -S
    King Abdulaziz University, Saudi Arabia.
    Danish, M.
    State Environ. Protect. Key Lab. of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Naqvi, S.
    School of Chemical and Materials Engineering, NUST, Pakistan.
    Farooq, U.
    State Environ. Protect. Key Lab. of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Qureshi, A. S.
    Institute of Biotechnology and Genetic Engineering, University of Sindh, Pakistan.
    Rehan, M.
    King Abdulaziz University, Saudi Arabia.
    Gasification Integrated with Small Chemical Pulp Mills for Fuel and Energy Production2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 977-983Article in journal (Refereed)
    Abstract [en]

    Pulp mills without black liquor recovery cycle could play a major role in employing black liquor gasification (BLG) to produce transport fuels. In conventional chemical pulp mills, black liquor is burnt in recovery boilers to generate steam and electricity to meet energy demands. The inorganic chemicals are reused for the digestion process. However, the energy content and inorganic chemicals are not recovered in small scale pulp mills especially in the developing countries which do not employ recovery cycle. This study investigates the potential of synthetic natural gas (SNG) production by integrating BLG island with a reference pulp mill without chemical recovery cycle. The improvements in overall energy efficiency are evaluated using performance indicators such as biofuel production potential, integrated system’s efficiency, and energy ratios. The oxygen-blown circulating fluidized bed (CFB) gasification with direct causticization is integrated with reference pulp mill. The results showed considerable SNG production without external biomass import. However to compensate total electricity deficit, the electricity will be imported from the grid. There is a substantial CO2 abatement potential of combining CO2 capture using seloxol absorption, and CO2 mitigation from SNG by replacing gasoline. 

  • 157.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Karlstad University, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology (KTH), Sweden.
    Naqvi, S. R.
    NUST, Pakistan.
    Nizami, A. S.
    King Abdulaziz University, Saudi Arabia.
    Salman, Chaudhary Awais
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Danish, M.
    ECUST, China.
    Farooq, U.
    ECUST, China.
    Rehan, M.
    King Abdulaziz University, Saudi Arabia.
    Khan, Z.
    University of Glasgow, United Kingdom.
    Qureshi, A. S.
    University of Sindh, Pakistan.
    Polygeneration system integrated with small non-wood pulp mills for substitute natural gas production2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 224, p. 636-646Article in journal (Refereed)
    Abstract [en]

    This study aims to examine the potential substitute natural gas (SNG) production by integrating black liquor gasification (BLG) island with a small wheat straw-based non-wood pulp mills (NPM), which do not employ the black liquor recovery cycle. For such integration, it is important to first build knowledge on expected improvements in an overall integrated non-wood pulp mill energy system using the key performance indicators. O2-blown circulating fluidized bed (CFB) gasification with direct causticization is integrated with a reference small NPM to evaluate the overall performance. A detailed economic analysis is performed together with a sensitivity analysis based on variations in the rate of return due to varying biomass price, total capital investment, and natural gas prices. The quantitive results showed considerable SNG production but significantly reduced electricity production. There is a substantial CO2 abatement potential combining CO2 capture and CO2 mitigation from SNG use replacing compressed natural gas (CNG) or gasoline. The economic performance through sensitivity analysis reflects significant dependency on both substitute natural gas production and natural gas market price. Furthermore, the solutions to address the challenges and barriers for the successful commercial implementation of BLG based polygeneration system at small NPMs are discussed. The system performance and discussion on the real application of integrated system presented in this article form a vital literature source for future use by large number of small non-wood pulp industries.

  • 158.
    Naqvi, Muhammad Raza
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Complementing existing CHP plants using biomass for production of hydrogen and burning the residual gas in a CHP boiler2017In: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277, no 6, p. 675-683Article in journal (Refereed)
    Abstract [en]

    Biorefinery systems at combined heat and power (CHP) plants represent numerous technical, economic and environmental benefits by utilizing the existing biomass handling infrastructure and producing biofuels together with heat and power. This study evaluates the economic feasibility of integrating biomass gasification to an existing CHP plant. Integration includes biomass gasification with downstream processing of the synthesis gas to remove particles and tars, condense out water, remove CO2 and use membrane filtration (polyamide membrane) to extract hydrogen. The separated residual gas components are utilized as extra fuel to the boiler in the CHP plant. Approximately 58.5 MWth of synthesis gas can be produced from a 90 MWth plant that represents 16.4 MWthof hydrogen. The rest of the heating value of produced synthesis gas (in the form of methane and carbon monoxide) is utilized for heat and power production. From an economic perspective, the production cost of hydrogen is estimated to be 0.125–0.75 €/kg. This can be compared to the US governments goal that H2 produced by wind power plus electrolyzers should have a maximum cost of 2.8–3.4 €/kg. The lower cost is for a unit operating at 3 bar and assuming that the costs are split between H2 and the syngas residue that is combusted, while the higher prices assume an atmospheric gasifier and all costs are put on the H2 produced.

  • 159.
    Naqvi, Muhammad Raza
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jan, Yinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, Salman Raza
    National University of Sciences & Technology (NUST), Pakistan.
    Off-grid electricity generation using mixed biomass compost:: A scenario-based study with sensitivity analysis2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 201, p. 363-370Article in journal (Refereed)
    Abstract [en]

    The aim of the study is to investigate the viability of waste gasification based off-grid electricity gener- ation utilizing mixed biomass composts (mixture of rice hulls with cow/poultry manure compost). The economic viability is studied on the different scenarios with considerations of (1) levels of electricity demand and utilization, (2) costs of variable biomass mix, (3) combined domestic and cottage industry business model, and (4) influence of governmental investments. The levelized cost of electricity (LCOE) is used as an indicator to measure the competitiveness of gasification based off-grid electricity genera- tion. The plant loading and the capacity factor have been used to assess the impacts of different scenarios. A sensitivity analysis of key parameters based on variations in annual operational hours, plant efficiency, plant cost and biomass supply cost is conducted. Based on levels of electricity demand and utilization, the LCOE ranged between 40 US cents/kW h and 29 US cents/kW h based on the plant loading and the capac- ity factor. The business revenue would not change considerably despite better plant utilization and reduced levelized cost of electricity if all the consumers, both basic or medium, are charged with the flat tariff. The part load operation will be costly despite considerably low capital investment per kW in com- parison with PV or solar based plants. There is a large potential of off-grid electricity generation but the estimated off-grid electricity price is found to be higher in all scenarios than average grid-based electric- ity tariff. Moreover, the challenges for the implementation of the real off-grid electricity generation plant are discussed. 

  • 160. Naqvi, Muhammad
    et al.
    Suleman, Tahir M
    Jinyue, Yan
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    POTENTIAL OF SYNTHETIC GASPRODUCTION FROM BLACK LIQUORGASIFICATION BASED BIO-REFINERYSYSTEM INTEGRATED WITH KRAFTPULP MILLS IN PAKISTAN2013Conference paper (Refereed)
  • 161.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Department of Chemical Engineering and Technology, KTH.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Bio-refinery system in a pulp mill for methanol production with comparison of pressurized black liquor gasification and dry gasification using direct causticization2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 90, no 1, p. 24-31Article in journal (Other academic)
    Abstract [en]

    Black liquor gasification (BLG) for bio-fuel or electricity production at the modern pulp mills is a field incontinuous evolution and the efforts are considerably driven by the climate change, fuel security, andrenewable energy. This paper evaluates and compares two BLG systems for methanol production: (i) oxygenblown pressurized thermal BLG; and (ii) dry BLG with direct causticization, which have beenregarded as the most potential technology candidates for the future deployment. A key objective is toassess integration possibilities of BLG technologies with the reference Kraft pulp mill producing1000 air dried tonnes (ADt) pulp/day replacing conventional recovery cycle. The study was performedto compare the systems’ performance in terms of potential methanol production, energy efficiency,and potential CO2 reductions. The results indicate larger potential of black liquor conversion to methanolfrom the pressurized BLG system (about 77 million tonnes/year of methanol) than the dry BLG system(about 30 million tonnes/year of methanol) utilizing identical amount of black liquor available worldwide(220 million tDS/year). The potential CO2 emissions reduction from the transport sector is substantiallyhigher in pressurized BLG system (117 million tonnes/year CO2 reductions) as compared to dry BLGsystem (45 million tonnes/year CO2 reductions). However, the dry BLG system with direct causticizationshows better results when considering consequences of additional biomass import. In addition,comparison of methanol production via BLG with other bio-refinery products, e.g. hydrogen, dimethylether (DME) and bio-methane, has also been discussed.

  • 162.
    Naqvi, Muhammad
    et al.
    KTH, Energiprocesser.
    Yan, Jinyue
    KTH, Energiprocesser.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Integrated Synthetic Natural Gas Production from Oxygen Blown Dry Black Liquor Gasification Process with Direct Causticization2011Conference paper (Refereed)
  • 163.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH, Energiprocesser.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH, Energiprocesser.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Sustainability Aspects of Transport Bio-fuels from Black liquor gasification – a System AnalysisIn: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777Article in journal (Other academic)
  • 164.
    Naqvi, Muhammad
    et al.
    KTH.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Synthetic gas production from dry black liquor gasification process using direct causticization with CO2 capture2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 97, p. 49-55Article in journal (Refereed)
    Abstract [en]

    Synthetic natural gas (SNG) production from dry black liquor gasification (DBLG) system is an attractive option to reduce CO2 emissions replacing natural gas. This article evaluates the energy conversion performance of SNG production from oxygen blown circulating fluidized bed (CFB) black liquor gasification process with direct causticization by investigating system integration with a reference pulp mill producing 1000 air dried tonnes (ADt) of pulp per day. The direct causticization process eliminates use of energy intensive lime kiln that is a main component required in the conventional black liquor recovery cycle with the recovery boiler. The paper has estimated SNG production potential, the process energy ratio of black liquor (BL) conversion to SNG, and quantified the potential CO2 abatement. Based on reference pulp mill capacity, the results indicate a large potential of SNG production (about 162 MW) from black liquor but at a cost of additional biomass import (36.7 MW) to compensate the total energy deficit. The process shows cold gas energy efficiency of about 58% considering black liquor and biomass import as major energy inputs. About 700 ktonnes per year of CO2 abatement i.e. both possible CO2 capture and CO2 offset from bio-fuel use replacing natural gas, is estimated. Moreover, the SNG production offers a significant fuel replacement in transport sector especially in countries with large pulp and paper industry e.g. in Sweden, about 72% of motor gasoline and 40% of total motor fuel could be replaced.

  • 165.
    Naqvi, Muhammad
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, S. R.
    National University of Sciences and Technology (NUST), Islamabad, Pakistan.
    Waste Biomass Gasification Based off-grid Electricity Generation: A Case Study in Pakistan2016In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 103, p. 406-412Article in journal (Refereed)
    Abstract [en]

    The objective is to investigate the waste gasification based off-grid electricity generation in developing countries like Pakistan utilizing mixed biomass composts (mixture of agricultural wastes including rice hulls and wheat straw with cow/poultry manure compost). Different scenarios are compared; (1) levels of electricity demand and utilization, (2) costs for variable biomass mix, (3) combined domestic and cottage industry business model. The levelized cost of electricity (LCOE) is used as an indicator to measure the competitiveness of off-grid electricity generation. There is a large potential of off-grid electricity generation. However, the estimated off-grid electricity price is found to be higher in all scenarios than average governmental electricity tariff.

  • 166.
    Nehrenheim, Emma
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering.
    Odlare, Monica
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering.
    Fredrik, Vallin
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Eva, Thorin
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering.
    Algal blooms - an environmental problem or a potential energy resource? the potentials for algae cultivation in lake Mälaren, an eutrophicated lake in Sweden2010Conference paper (Refereed)
  • 167.
    Nylander, Michelle
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Aparicio Tomas, Elena
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    ANALYSIS AND OPTIMIZATION OF ENERGY FLOWS IN A PULP MILL2008In: Proceedings of Control Systems,  2008 / [ed] Andrea Borrelli, Vancouver: TAPPI Press , 2008Conference paper (Refereed)
    Abstract [en]

    In this paper the digester house process variables

    are first studied to identify the process variations in

    different time perspectives. The focus is on the

    perspective of controlling the process on-line for

    the next 24 hours. With a mathematical model first

    the cook and the flows associated with the digester

    house are modelled. From this different scenarios

    with different “faults” are implemented in the

    model and compared to the process data. From this

    the performance can be predicted for different

    conditions. Key numbers are determined from this

    and these are used together with suitable objective

    functions to make optimal production planning for

    model based control. The set points are sent to the

    control system. By determining the reactivity of

    different qualities of wood chips by measuring NIR

    and measuring final kappa, a tool for feed forward

    control is developed.

  • 168.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Axrup, Lars
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Långtidsutvärdering av nya on-line fukthaltsmätare för biobränsle [Long-term evalution of on-line sensors for determination of moistrue in biomass]2002Report (Other academic)
  • 169.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Methods for determination of moisture content in woodchips for power plants - a review2004In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 83, no 7-8, p. 773-779Article in journal (Refereed)
  • 170.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Thorin, E.
    Backa, S.
    Dahlquist, Erik
    Filling level measurement in woodchips bins with radio-frequency spectroscopy2003In: Nordic seminar on thermochemical conversion of biofuels, Nov. 12, 2002, 2003Chapter in book (Other academic)
  • 171.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Thorin, Eva
    Backa, Stefan
    Dahlquist, Erik
    Moisture Content Measurements on Sawdust with Radio Frequency Spectroscopy2005In: Proceedings of ASME Power, Chicago, Illinois, USA, April 5-7, 2005(2005), 2005Conference paper (Refereed)
  • 172.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Starfelt, Fredrik
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    How to achieve a fossil fuel free Malardalen region2007In: Conference proceedings of 3rd IGEC-2007,, 2007Conference paper (Refereed)
  • 173.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    A new method for bulk measurement of water content in woody biomass2008In: 3rd Conference on environmental compatible forest products, 2008Conference paper (Refereed)
  • 174.
    Porian, Bijan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Modelling of the Chemical Reactions in a Continuous Pulping Digester in the Presence of the Channelling Phenomenon2009In: International Review of Chemical Engineering Rapid Communications, ISSN 2035-1755, Vol. 1, no 5, p. 419-427Article in journal (Refereed)
    Abstract [en]

    Pulping digester including the channelling phenomenon and chemical reactions in the channel is modelled using the CFD, finite volume method, FLUENT. The objective of this paper is to predict the chemical and hydraulic behaviour of the digester under the hazardous situations.

    A 2D geometry of the digester is built and symmetric planes are defined in the Gambit. The mesh is then exported to the FLUENT and then the created half geometry was treated by axisymmetric function to establish a complete model of the digester. The Eulerian scheme is applied which    represent the multiphase flows in the digester. A heterogeneous porous media is defined for the compressible bed. Species transport is applied to define a mixture template of the wood chips components. The kappa number is predicted in the channel and around it to characterize the cooking development under hazardous conditions.               

  • 175.
    Pourian, Bijan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    CFD modeling of the continuous chemical interaction between the multiphase flows of the pulp and paper digester using the mass transfer scheme2011In: World Journal of Modelling and Simulation, ISSN 1746-7233, Vol. 7, no 3, p. 189-205Article in journal (Refereed)
    Abstract [en]

    This paper describes the construction of a computational fluid dynamics (CFD) code for the physical structure of a pulping reactor and prediction of the continuous chemical reactions inside the digester. Models of chemical interactions between the wood chips and liquor flow in a pulping digester were designed using the finite volume method (FVM) in FLUENT. The quality of the produced pulp was computed throughout the reactor from the top inlet to the bottom outlet by modeling the Kappa number, a dimensionless parameter that describes lignin content. A conjugated mass transfer and porous media model was tested for its usefulness in avoiding the effect of granular instability and divergence on the chemical reaction model.

  • 176.
    Pourian, Bijan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    CFD modelling of solid-liquid multiphase and mathematical separation of the phases in a continuous pulp digester2010In: International Journal of Modelling and Simulation, ISSN 0228-6203, Vol. 30, no 3, p. 384-395Article in journal (Refereed)
    Abstract [en]

    This paper describes the use of a CFD multiphase model using commercial FLUENT software to aid understanding of the physical behavior of solid and liquid flows in the digester of the pulping process. We take into consideration the mass balance of the multi-inlets, outlets and circulation flows in the digester. We also look at the application of a Porous media model to describe the dynamic behavior of the liquor flow through a bed of solid particles.

    The cylindrical Korsnas/vallvik pulping digester in Sweden is represented in the models as an axisymmetric two-dimensional model, which includes multiple feeds, outlets, pressure adjustment valves and circulation pipes.

    Separation of the phases is an important part of the pulping process. A number of multiphase models are evaluated for their potential use in phase separation.

    For this evaluation we constructed the two-dimensional digester model in the Gambit software package, a pre- processor tool for FLUENT 

    Physical strainers at the entrances of outlet pipes were designed in Gambit, in order to investigate the possibility of physically separating large solid particles from the liquid flow where both phases are subject to suction into the circulation pipes.

    The compaction of the wood chips is also considered in the modeling. In the Porous model, the digester is divided into sections of different porosity, and the behavior of individual suspension particles  is not considered. The bulk of this paper concerns modeling mass balances and phases of the mixture in the digester using Eulerian and Mixture strategies.

  • 177.
    Pourian, Jan Bijan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Modelling and simulation of chemical reactions between wood chips and white liquor in a continuous pulping digester  2011In: Proceedings of the IASTED International Conference on Modelling and Simulation, 2011, p. 150-160Conference paper (Refereed)
    Abstract [en]

    Chemical interactions between the fibers of cellulose and liquor flow in a continuous pulping digester were modeled using CFD, (Computational Fluid Dynamic) and the finite volume method (FVM). A 2D geometric representation of the digester was constructed in Gambit. The total volume of the reactor was considered using the axisymmetric function of FLUENT. CFD is a numerical solution method of PDE (Partial Differential Equations) in many different control volumes such as pipes, reactors, vessels or any component. Differential form of the conservation equations of mass, momentum and energy (including the chemical reactions) are solved using the CFD codes. In order to avoid complications arising from instability and divergence, the circulation flows around the digester were ignored. The calculations were performed for the pulping of softwood chips. In order to model the kinetics of the pulping reactions, the chemical reactions of the fibers were calculated theoretically and the Arrhenius constants for the reactions were computed. The activation energy was also calculated according to data provided for the cooking conditions. The stoichiometry of the reaction equation was determined from the operational data of the cooking process. The stoichiometry and Arrhenius parameters were prescribed by CFD codes in order to characterize the pulping chemical reactions in the digester. The reaction was modeled under isothermal conditions. The species transport and reaction scheme were incorporated with a homogeneous porous media to represent compaction of the fibers in the digester. The progress of the reaction represents the quantitative development of the pulping process. However, the qualitative progress is controlled by the stoichiometry of the reaction. This means that a good model of the reaction stoichiometry can ensure continuous production of high quality pulp.

  • 178.
    Pourian, Jan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Modelling of the channelling phenomenon of the pulping digester using porous Media2009In: SIMS, Scandinavian Modelling and Simulation  Society 50, conference in Fredrice, Denmark, October 7-8 (2009) / [ed] Brian Elmegard, Fredrice: SIMS electronic , 2009Conference paper (Refereed)
    Abstract [en]

    A dynamic model is developed for a continuous pulping digester to characterize the channeling phenomenon. The commercial CFD codes, FLUENT, are used to compute the hydraulic behavior of the digester under the normal and particular operational conditions. All the circulation flows, extractions, multiple inlets and outlets are included in this model. The digester is designed in the Gambit and an axisymmetric 2d model is applied. A porous scheme is implemented in the model in order to design the fluid flow and channelling phenomenon inside the digester. A heterogeneous porous media is specified in order to take the compression of the pulp into account. The simulation can serves as a prognosis model to predict the risk situations and probably to hinder high economical damage. The k- model contributes to compute the flow “regimes” or eventual eddies in some turbulent zones of the digester.

  • 179.
    Pourian, Jan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Irwin, Mark
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Numerical and experimental study of the inclined free fins applied for thermal management2009In: / [ed] Erik Dahlquist, Västerås: Mälardalen University , 2009, p. 164-181Conference paper (Refereed)
    Abstract [en]

    A new design for copper base heatsink is proposed in this work. In some experimental and numerical simulation efforts, optimizing and predicting of the thermal characterization of the heatsink with inclined free fins is developed. The proposed copper heatsink has high thermal dissipation capability and lower weight and volume compare to current aluminum and copper heatsinks.

    The model is scaled up in the fluent environment to predict its application in the cooling of larger heat generated electronic devices.

    Free fin denotes that the fins are not integrated chemically by casting methods and also implies that the proposed heatsink consist of individual and separated fins that are assembled and holds together. Impingement air-cooling mode of force-convection is adopted for heat dissipation from high power electronic devices in associated with the proposed inclined fin model. In addition to larger surface area and airflow velocity another solution for enhancement of heat dissipation is suggested. A numerical evaluation of thermal performance of the suggested heatsink and fluid flow around the fins is performed. The thermal performance is estimated also by experimental variables. The results of experimental investigation and CFD studies are introduced in this paper. Construction method of proposed heatsink by suggested fin design is introduced. This heat sink is fabricated mechanically and is tested by a number of heat sources and high sensitive devices such as adhesive k type thermocouple, data acquisition 34970A in associated with HP Bench Link program.  Components of airflow velocity in the hollow spaces of the heatsink are discussed. Pressure drop and other thermal variables are analyzed analytical and by CFD code

  • 180.
    Pourian, Jan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Irwin, Mark
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Numerical modeling of two proposed mechanically fabricated free-fins heat sinks2009In: Proceedings of EuroSimE 2009, 2009, p. 393-404Conference paper (Refereed)
    Abstract [en]

    Two new designs for copper base heat sink is proposed in this work. In some experimental and numerical simulation efforts, optimizing and predicting of the thermal characterization of the heat sink with inclined free fins is developed. A new design of the base and fins optimized both with respect to manufacture ability and performance is introduced. The proposed copper heat sinks have high thermal dissipation capability and lower weight and volume compare to current aluminum and copper heat sinks. The inclined free fins model is scaled up in the fluent environment to predict its application in the cooling of larger heat generated electronic devices. Free fin denotes that the fins are not integrated chemically by casting methods and also implies that the proposed heat sink consist of individual and separated fins that are assembled and holds together. Impingement air-cooling mode of force-convection is adopted for heat dissipation from high power electronic devices in associated with the proposed inclined fin model. The hydraulic parameters computed for square fin model include velocity profiles, distribution of static pressure, dynamic pressure, boundary layer and fluid temperature between the fins and in the passageway at the middle of the heat sink. Furthermore 3-dimensional temperature distribution through the fins and base and heat source is predicted. In addition to larger surface area and airflow velocity another solution for enhancement of heat dissipation is suggested. Numerical prediction of the thermal performance of the free fins heat sink is conducted. The thermal performance is also estimated by experimental efforts. The results of experimental investigation and CFD studies are introduced in this paper. Construction method of proposed heat sinks by suggested fin design is introduced. The free fin heat sink is fabricated mechanically and is tested by a number of heat sources and high sensitive devices such as adhesive k type thermocouple, data acquisition 34970A in associated with HP Bench Link program. Components of airflow velocity in the hollow spaces of the heat sink are discussed. Pressure drop and other thermal variables are analyzed analytically and by CFD code.

  • 181.
    Rahman, Moksadur
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    An Approach For Feedforward Model Predictive Control For Pulp and Paper Applications: Challenges And The Way Forward2017In: Paper Conference and Trade Show, PaperCon 2017: Renew, Rethink, Redefine the Future, Volume 3, TAPPI Press, 2017, Vol. 10, p. 1441-1450Conference paper (Refereed)
    Abstract [en]

    Due to the naturally varying feedstock, significant residence time, insufficient measurements and complex nature of the delignification process, producing pulp with consistent quality i.e. stable kappa number with sufficiently high yield is a challenging task that requires multi-variable process control. A wide variety of control structures, ranging from classical concepts like cascade control, feedforward, ratio control, and parallel control to more modern concepts like model-based predictive control, is used in pulp and paper industries all over the world. In this paper, a survey of model-based predictive control will be presented along with the control challenges that lie within the chemical pulping process. The potential of this control concept for overcoming the aforementioned technical challenges will also be discussed in the second part of the paper. Particular focus will be given on the use of near-infrared spectroscopy based soft-sensors coupled with dynamic process models as an enabler for feedforward model-based predictive control. Overall, the proposed control concept is expected to significantly improve process performance, in the presence of measurement noise and various complex chemical process uncertainties common in pulp and paper applications.

  • 182.
    Rahman, Moksadur
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jansson, Johan
    Billerud Korsnäs, Gävle, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Model based Control and Diagnostics strategies for a Continuous Pulp Digester2018In: Paper Conference and Trade Show, PaperCon 2018, 2018, Vol. 1, p. 136-147Conference paper (Refereed)
    Abstract [en]

    Kappa number, which essentially indicates the amount of lignin left in the pulp after cooking, is the most important physical quantity linked to the quality and economics of a Kraft-pulp mill. Controlling the Kappa number is a difficult task mainly due to the naturally varying feedstock, significant residence time, insufficient measurements and complex nature of the delignification process. Moreover, faults such as screen clogging, hang-ups and channeling in the process often occur and increase the operational costs considerably. In this work, the possibility of feedforwarding the lignin content of incoming wood chips, by a near-infrared spectroscopic measurement of one of the major process disturbances, to a model predictive controller, is investigated by means of modeling and simulation studies. Additionally, a simple Bayesian network based diagnostics approach is proposed to detect the continuous digester faults.

  • 183.
    Rodriguez, Adrian
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Påhlson, Carl
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Odlare, Monica
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Färm, Carina
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Fluorescence in situ hybridization (FISH) for quantification of species of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in wastewater treatment activated sludge.2009Conference paper (Refereed)
  • 184.
    Rodriguez Caballero, Adrian
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hallin, S
    Swedish Univ Agr Sci.
    Påhlson, Carl
    Uppsala Univ.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Ammonia oxidizing bacterial community composition relates to process performance in wastewater treatment plants under low temperature conditions2012In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 65, no 2, p. 197-204Article in journal (Other academic)
    Abstract [en]

    Nitrification can be difficult to maintain at wastewater treatment plants (WWTPs) during cold periods resulting in disrupted nitrogen removal. The aim of this study was to relate nitrification process performance to abundance and composition of the ammonia oxidizer communities in two closely located municipal WWTPs in Sweden during an eight month period covering seasonal changes and low temperature conditions. Both facilities showed lower NH4+-N removal efficiency and nitrification rates as temperature decreased. However, one of the plants had a more stable nitrification rate and higher ammonia removal efficiency throughout the entire period. The differences in performance was related to a shift in the composition of the bacterial ammonia oxidizing community from a Nitrosomonas oligotropha-dominated community to a mixed community including also Nitrosomonas ureae-like ammonia oxidizers. This was likely a response to differences in NH4+-N and organic loading.

  • 185.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Future directions for CHP plants using biomass and waste - Adding production of vehicle fuels2019In: E3S Web of Conferences, EDP Sciences , 2019, article id 01006Conference paper (Refereed)
    Abstract [en]

    In Northern Europe, the production of many biobased CHP plants is getting affected due to the enormous expansion of wind and solar power. In addition, heat demand varies throughout the year, and existing CHP plants show less technical performance and suffer economically. By integrating the existing CHP plants with other processes for the production of chemicals, they can be operated more hours, provide operational and production flexibility and thus increase efficiency and profitability. In this paper, we look at a possible solution by converting an existing CHP plant into integrated biorefinery by retrofitting pyrolysis and gasification process. Pyrolysis is retrofitted in an existed CHP plant. Bio-oil obtained from pyrolysis is upgraded to vehicle grade biofuels. Gasification process located upfront of CHP plant provides the hydrogen required for upgradation of biofuel. The results show that a pyrolysis plant with 18 ton/h feed handling capacity (90 MWth), when integrated with gasification for hydrogen requirement and CHP plant for heat can produce 5.2 ton/h of gasoline/diesel grade biofuels. The system integration gives positive economic benefits too but the annual operating hours can impact economic performance. 

  • 186.
    Sandberg, Jan
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Fdhila, Rebei Bel
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering.
    Dynamic simulation of fouling in a circulating fluidized biomass fired boiler2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 5, p. 1813-1824Article in journal (Refereed)
    Abstract [en]

    A dynamic model is presented for a biomass-fired circulating fluidized bed boiler. The model is based on energy and mass balances for the components in the boiler and on a combustion model for the fluidized bed. The main purpose of the model is to simulate how deposits affect the boiler efficiency and performance. The model is verified against the municipal circulating fluidized bed boiler in Vasteras, Sweden, which produces 157 MW. The distribution of deposits on the surfaces in the boiler is well known from inspections. These observations are used as inputs to the model to simulate their effects on boiler performance. The heat exchanger most affected by fouling is Superheater 2, which is the first heat exchanger in the flue gas channel. Deposits typically reduce the heat transfer rate by half over a season despite soot blowing. This and other fouling scenarios are simulated and presented in this article. The simulations show that fouling on superheaters redistributes the heat transfer rate from the superheaters to Reheater 1 and partially redistributes turbine power from the high pressure turbine to the intermediate pressure turbine. If the boiler is running at maximum load, water injection to Reheater 1 has to increase to maintain temperatures below the permitted limit. The dynamic effects of fouling are small and the total efficiency of the boiler is only marginally affected. Fouling on evaporating surfaces has major dynamic effects and dramatically decreases the boiler efficiency. A decrease in fuel rate flow is needed to maintain temperatures in the fluidised bed and in the flue gas channel within acceptable limits.

  • 187.
    Segelod, Esbjörn
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Berglund, KarinMälardalen University, School of Innovation, Design and Engineering.Bjurström, ErikMälardalen University, School of Innovation, Design and Engineering.Dahlquist, ErikMälardalen University, School of Sustainable Development of Society and Technology.Hallén, LarsMälardalen University, School of Sustainable Development of Society and Technology.Johanson, UlfMälardalen University, School of Sustainable Development of Society and Technology.
    Studies in Industrial Renewal: Coping with Changing Contexts2011Collection (editor) (Refereed)
    Abstract [en]

    The purpose of this book is to provide a picture of ongoing research at Mälardalen University in order to create a point of departure for future research on industrial renewal. Many aspects of industrial renewal are dealt with by the researchers who contributed to this book. Some of them focus on functional aspects such as distribution channels and management accounting and control. Others deal with broad perspectives such as strategies and entrepreneurship, and still others consider specific empirical fields such as the institutions of society, and the energy sector.

    Our exposition identifies a need for further research into classical problems such as how to best exploit new ideas in established firms, as well as how to infuse new approaches and attitudes into going concerns, the role of the characteristics of industrial networks, geographical distance, the labour market, and the institutions of society in such renewal processes, and the need for more in-depth process research in order to further develop theory and practice.

  • 188.
    Silvestrov, Dmitrii
    et al.
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Dahlquist, ErikMälardalen University, School of Business, Society and Engineering, Future Energy Center.Malyarenko, AnatoliyMälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.Borisenko, OlexandrKiev University, Ukraine.
    Proceedings of the International School “Finance, Insurance, and Energy Markets –       Sustainable Development”2008Conference proceedings (editor) (Refereed)
  • 189.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sandberg, Jan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    The experimental study of full-scale biomass-fired bubbling fluidized bed boiler2014In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, p. 643-647Article in journal (Refereed)
    Abstract [en]

    This paper presents experimental data concerning combustion characteristics of full-scale biomass-fired bubbling fluidized bed (BFB) steam boiler with a thermal output of 31 MW. The purpose of the experimental measurements is to show how the values of selected combustion parameters vary in reality depending on measurement position. Experimentation involves specifically a determination of combustion gas temperature and concentration of gas species i.e. O2, CO2, CO and NOX at different positions in the furnace and the flue gas trains. Character of results from the furnace indicates the intermediate stage of thermochemical reactions. Increased levels of CO close to the wall have been found, this may be indicating reducing atmosphere and thereby increased corrosion risk. Results from flue gas trains demonstrate that behavior there is related to the fluid dynamics and heat transfer, the temperature is too low for further combustion reactions. Results show great variations among measured values of all measurands depending on a distance along the line from the wall to the center of the boiler. The measurements from permanently installed fixed sensors are not giving value representing average conditions, but overall profiles can be correlated to online measurements from fixed sensors.

  • 190.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Application of Near Infrared Spectroscopy for Rapid Characterization of Feedstock Material in Pulp and Paper Industry2015In: Book of abstracts, 2015Conference paper (Refereed)
    Abstract [en]

    Pulp digesters can be continuous or batch reactors with significant residence time which are fed with woodchips and cooking chemicals. They deliver the pulp-fibers that are used in the production of paper, as well as black liquor that is combusted in the chemical recovery boiler. The possibility to measure what is happening inside the digester is limited. The most important quality properties of the feedstock material is content of lignin, which is being dissolved during the process, and related material reactivity. Pulp quality after the process is measured by Kappa number which is a measure of residual lignin in the pulp. One of the biggest challenges in pulp production process is the great variability in feedstock material properties. If the process is not adjusted by well-timed and appropriate operational control measures i.e. control of inlet and outlet flows and setting of the cooking recipe, it will result in the large variations in Kappa number, lower fiber quality or excess use of environmentally harmful cooking chemicals. This becomes particularly important during the swing between softwood and hardwood as part of meeting the final paper product quality requirements. Therefore, a rapid method that is capable of continuous feedstock material characterization is required.Near infrared (NIR) spectroscopy can be used for non-destructive characterization of the feedstock material. In this study, both Fourier transform and grating NIR spectrophotometers were used for NIR absorbance spectra acquisition. Each spectrum was recorded in the range between 700 and 2500 nm. During the calibration of spectra of various wood species with known lignin content, wood samples were placed on a tray so that the tray may move horizontally in a reciprocating manner underneath the sensor while maintaining the constant distance between the sensor and sample. This was done in order to simulate the movement of a real conveyor belt as used for transporting feedstock to the digester. In the on-line application the NIR meter is situated above the conveyor belt that wood up to the digester.Spectral data were pretreated with different methods such as normalization, scatter correction, smoothing, first and second derivative (Savitzky-Golay algorithm), selection of different spectral ranges and its combinations. Mathematical models to estimate lignin content were constructed using Partial Least Square Regression (PLS-R) and Principle component regression (PCR) statistical methods. Response data for model build-up were determined in the chemical laboratory according to standardized procedures including test repetitions. Different combinations of NIR instrument used, pre-treatment methods and statistical methods were evaluated in order to find the model with the best prediction performance.Results are promising and demonstrate that it is possible to characterize the lignin content and reactivity of the feedstock material by NIR spectrophotometers with reasonable prediction model performance. Improved prediction can be obtained if only selected spectral ranges are included as an input for statistical modelling; similarly using derivatives is better than using the raw spectrum. In the next step, developed statistical models for rapid lignin content prediction will be used as a feed-forward input for dynamic process control.

  • 191.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Effect of wood chip moving velocity on NIR spectra acquisition and model calibration for lignin quantificationManuscript (preprint) (Other academic)
  • 192.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Fast Determination of Fuel Properties in Solid Biofuel Mixtures by Near Infrared Spectroscopy2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 1309-1317Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the characterization of highly variable biofuel properties such as moisture content, ash content and higher heating value by near-infrared (NIR) spectroscopy. Experiments were performed on different biofuel sample mixtures consisting of stem wood chips, forest residue chips, bark, sawdust, and peat. NIR scans were performed using a Fourier transform NIR instrument, and reference values were obtained according to standardized laboratory methods. Spectral data were pre-processed by Multiplicative scatter correction correcting light scattering and change in a path length for each sample. Multivariate calibration was carried out employing Partial least squares regression while absorbance values from full NIR spectral range (12,000–4000 cm-1), and reference values were used as inputs. It was demonstrated that different solid biofuel properties can be measured by means of NIR spectroscopy. The accuracy of the models is satisfactory for industrial implementation towards improved process control. 

  • 193.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Fast Determination of Lignin Content in Feedstock Material for Pulping Process Monitoring and Optimization2015In: ICAVS 8 - Abstracts poster, 2015, p. 556-557Conference paper (Refereed)
    Abstract [en]

    Pulping process is delivering pulp fibers which are further used in the production of paper. The reactor is fed with feedstock material in the form of wood chips. Moreover, cooking chemicals are brought at several points into the reactor. Previous studies have shown that the knowledge of the feedstock material properties which are highly variable is limited. One of the most important parameters is the lignin content, which has to be dissolved, this requires a significant residence time. The residual lignin in the resulting pulp after the process is measured in the form of Kappa number. Inappropriate application of cooking chemicals could lead to large variations in the Kappa number, low fiber quality and other issues. Therefore continuous characterization of the feedstock material is required. One of the available methods for nondestructive characterization of feedstock material is NIR spectroscopy. Presented study is conducted in order to assess the possibility of determining lignin content using NIR method. The spectroscopy workflow consist of four major steps i.e. sample preparation, spectral data acquisition, data pre-processing and multivariate calibration. We used test samples from 13 different tree species, which were tested in the form of wood chips, pulverized wood and mixture of both. Acquired spectral data were pre-processed mainly by second derivative and standard normal variate transformation. PLS regression with full cross validation was used for the development of a calibration model based on selected wavelengths. Acquisition of reference variable has been done according to standardized procedures and it represents the total amount of lignin in the sample.

    The results of lignin characterization in feedstock material by NIR are very promising. The resulting PLS regressionmodel includes 2-factors and uses 16 predicting variables, resulting in R2 = 0,975, RMSE = 0,885 wt%. In the next step, presented work will be improved by applying large amount of samples, independent validation data set and by simulation of conveyor belt movements. The objective of this research is to test the NIR method at a real pulp digester, in order to improve monitoring andoptimization of the process. Furthermore, continuous characterization of the feedstock materials is intended to be used for the improvement of the control process. The measured lignin content will be compared to the content calculated within the pulp digester physical model and the Kappa number. This will be used for improving the digester physical model accuracy and as an input to advanced model based control, where the correlation will be made not only to lignin content but also with the feedstock material reactivity.

  • 194.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Multivariate analysis models for wood properties combined with Open Modelica model for process performance monitoring2015In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2015, Vol. 48:1, p. 898-899Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    To perform advanced model based control it is important to know what is fed into a system such as a waste or biomass fired boiler or a pulp digester. In this paper, we present correlations between the lignin content of different types of wood chips and their Near-infrared (NIR) spectra. The Principal Component Regression (PCR) method is used for deriving the correlation, as well as selecting certain wave lengths. Analysis is made including different parts of the spectra in the wave length range 700 – 2500 nm. The model is then used as input to an Open Modelica pulp digester model to tune the reactivity constant of the dissolution of lignin. The lignin content of wood-chips is determined on-line through the NIR measurement at the feed to the digester. Simulations are carried out to determine the content of residual lignin on fibers at the exit (continuous digester) or at the end of a cook (batch digester). By comparing the deviation between predicted values and actual measured values the reactivity constant of the lignin is determined. The regression can be made to the NIR spectrum aside of the lignin content as such. The original content of lignin together with reactivity may then be used for optimized on-line control of the digester. It can also be used for diagnostic purposes with regard to process issues like hang-ups or channeling, as well as possible sensor faults and data reconciliation.

  • 195.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Rapid Determination of Selected Compounds in Waste-based Fuel by Near Infrared Spectroscopy2015In: Book of abstracts, 2015Conference paper (Refereed)
    Abstract [en]

    Composition of the waste-based fuel intended for incineration has substantial effect on combustion process performance and formation of environmentally harmful emissions. Fuel composition vary significantly depending on the material source, waste sorting and recycling procedures and other waste pretreatment methods. In general, it typically contains paper, plastics, wood, textile, other organic material and further undesired substances including glass and metals. The knowledge of actual composition of the material fed into the boiler is limited to the direct or indirect continuous moisture content measurements and periodic fuel sampling providing elementary composition. This information is not sufficient for process control and performance optimization, particularly when considering strongly heterogeneous fuel feed. Therefore a rapid and reliable technique for fuel characterization is needed.The work presented here is focused to the quantitative determination of selected plastic materials and glass content. Incomplete combustion of different plastics may lead to the formation of carbon monoxide, hydrogen-cyanides, acid compounds and aromatic hydrocarbons etc. If the waste contains chlorine then highly chlorinated polycyclic compounds such as dioxins and furans may be formed. Plastics often contain flame retardants which can also contribute to production of harmful emissions. On the other hand, the highly corrosive deposits of alkali chlorides and other compounds may be formed on the heat exchangers, this lowers the heat transfer and boiler efficiency and decrease life-time of the equipment. Moreover, increased content of glass in the fuel supports the formation of agglomerates in the fuel bed, defluidization of the bed or ash removal problems which result in malfunction or failure of the combustion equipment.Near infrared (NIR) spectroscopy can be used for non-destructive quantitative determination of plastics and glass in waste-based fuel. Experimental work was performed on two types of spectrophotometers i.e. grating and Fourier transform instruments. Samples of known content of glass and different plastics were placed on a moving tray that reciprocated horizontally back and forth underneath the NIR sensor. This was done in order to replicate online application where the NIR spectrophotometer is places above the conveyor belt that transport the fuel to the boiler.Spectra were recorded in the range between 700 and 2500 nm. Acquired spectral data were pretreated with different methods such as normalization, scatter correction, smoothing, first and second derivative (Savitzky-Golay algorithm), selection of different spectral ranges and its combinations. Mathematical models to estimate content of glass and different plastics were constructed using Partial Least Square Regression (PLS-R) and Principle component regression (PCR) statistical methods. Different combinations of spectrophotometer type, pre-treatment methods and statistical methods were evaluated in order to find the model with the best prediction performance.Results prove the potential of the method to quantitatively determine the content of different types of plastics as well as glass with reasonable prediction accuracy. The ultimate goal of this research is to test the method at a real industrial boiler in order to improve process monitoring and control.

  • 196.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Utilization of Near Infrared (NIR) Spectrometry for Detection of Glass in the Waste-based Fuel2015In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, p. 734-741Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of experimental measurements and multivariate statistical modeling concerning detection of soda-lime glass using near infrared (NIR) spectrometry technique. The purpose is to test if the glass is quantitatively detectable in a waste-based material and to assess what method of spectral data pretreatment is the most suitable in order to develop prediction models. The experiments were performed on six test samples containing a specific amount of glass distributed in background material. Pretreatment methods such as normalization and first and second derivatives were applied on the acquired absorbance spectral data. Principal component analysis (PCA) was employed in order to describe the relationship between pretreated data and the amount of glass in the test samples. Subsequently, principal component regression (PCR) was utilized for the development of prediction models. The results from the models show strong correlation between the pretreated data and the glass content. The most promising results were obtained from the model based on 1st derivative pretreatment when only absorbance spectral data from selected wavelengths are included. 

  • 197.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sandberg, Jan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Erik, Dahlquist
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Experimental investigation of part load operation of a full-scale biomass-fired fluidized bed boilerManuscript (preprint) (Other academic)
  • 198.
    Skvaril, Jan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Applications of near-infrared spectroscopy (NIRS) in biomass energy conversion processes: A review2017In: Applied spectroscopy reviews (Softcover ed.), ISSN 0570-4928, E-ISSN 1520-569X, Vol. 52, no 8, p. 675-728Article in journal (Refereed)
    Abstract [en]

    Biomass used in energy conversion processes is typically characterized by high variability, making its utilization challenging. Therefore, there is a need for a fast and non-destructive method to determine feedstock/product properties and directly monitor process reactors. The near-infrared spectroscopy (NIRS) technique together with advanced data analysis methods offers a possible solution. This review focuses on the introduction of the NIRS method and its recent applications to physical, thermochemical, biochemical and physiochemical biomass conversion processes represented mainly by pelleting, combustion, gasification, pyrolysis, as well as biogas, bioethanol, and biodiesel production. NIRS has been proven to be a reliable and inexpensive method with a great potential for use in process optimization, advanced control, or product quality assurance.

  • 199.
    Stigson, Peter
    et al.
    COWI AB, Stockholm, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Policies and incentives - natural resources available today and in the future: How to perform change management for achieving a sustainable world2017In: Natural Resources Available Today and in the Future: How to Perform Change Management for Achieving a Sustainable World, Springer International Publishing , 2017, p. 269-280Chapter in book (Other academic)
  • 200.
    Takami, Kourosh Mousavi
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Mahmoudi, Jafar
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Adaptive control of cold rolling system in electrical strips production system with online-offline predictors2010In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 50, no 9-12, p. 917-930Article in journal (Refereed)
    Abstract [en]

    One of the main concerns of strips producers is to measure strip thickness accurately as it is produced. Correct modelling of the sensitivity of output variables to input variables in a rolling mill model is one of the keys to obtaining more accurate data. An adaptive control system that uses an artificial neural network (ANN) creates a model of the process directly from measurement data. Using the model, the control system can predict how the process will react to control actions. The creation of the model and the computation of the control strategy are carried out automatically by the control system. The proportional-integral-derivative controller is used in this method to increase accuracy of final estimated variables and to increase accuracy of control of the system. To determine the correct tuning for thickness control, three control parameters are considered: the roll gap, and front and back tensions. A predictive model is used, based on the sensitivity equations of the process, where the sensitivity factors are computed by differentiating a previously trained neural network. Results of a case study in a real plant show that this online-offline model is effective in reducing thickness variations in produced strips.

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