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  • 1.
    Dahlquist, Erik
    et al.
    Mälardalens högskola.
    Naqvi, Muhammad
    Mälardalens högskola.
    Thorin, Eva
    Mälardalens högskola.
    Yan, Jinyue
    Mälardalens högskola; KTH.
    Kyprianidis, Konstantinos
    Mälardalens högskola.
    Hartwell, Philip
    BioReg MiniMills Ltd, England.
    Experimental and numerical investigation of pellet and black liquor gasification for polygeneration plant2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 204, p. 1055-1064Article in journal (Refereed)
    Abstract [en]

    It is vital to perform system analysis on integrated biomass gasification in chemical recovery systems in pulp and paper and heat and power plants for polygeneration applications. The proposed integration complements existing pulp and paper and heat and power production systems with production of chemicals such as methane and hydrogen. The potential to introduce gasification-based combined cycles comprising gas turbines and steam turbines to utilize black liquors and wood pellets also merits investigation. To perform such analysis, it is important to first build knowledge on expected synthesis gas composition by gasifying at smaller scale different types of feed stock. In the present paper, the synthesis gas quality from wood pellets gasification has been compared with black liquor gasification by means of numerical simulation as well as through pilot-scale experimental investigations. The experimental results have been correlated into partial least squares models to predict the composition of the synthesis gas produced under different operating conditions. The gas quality prediction models are combined with physical models using a generic open-source modelling language for investigating the dynamic performance of large-scale integrated polygeneration plants. The analysis is further complemented by considering potential gas separation using modern membrane technology for upgrading the synthesis gas with respect to hydrogen content. The experimental data and statistical models presented in this study form an important literature source for future use by the gasification and polygeneration research community on further integrated system analysis. (C) 2017 Elsevier Ltd. All rights reserved.

  • 2. Khan, Z.
    et al.
    Yusup, S.
    Kamble, P.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Watson, I.
    Assessment of energy flows and energy efficiencies in integrated catalytic adsorption steam gasification for hydrogen production2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, p. 346-355Article in journal (Refereed)
    Abstract [en]

    This study addresses the energy flows and energy efficiency of integrated catalytic adsorption biomass steam gasification for hydrogen production in a pilot scale bubbling fluidized bed system utilizing palm kernel shell as feedstock. The integrated catalytic adsorption utilizes catalyst and CO2 adsorbent together in the single fluidized bed gasifier. Various variables such as effect of temperature (600–750 °C), steam to biomass ratio (1.5–2.5 w/w), adsorbent to biomass ratio (0.5–1.5 w/w), fluidization velocity (0.15–0.26 m/s) and biomass particle size (0.355–0.500 to 1.0–2.0 mm) are investigated. The results imply that the overall requirement of gasification energy increases with increasing gasification temperature, steam to biomass ratio, fluidization velocity, and decreases with adsorbent to biomass ratio whilst no significant increase is observed by varying the biomass particle size. However, a slight reduction in required energy is observed from 600 °C to 675 °C which might be due to strong CO2 adsorption, an exothermic reaction, and contributes to the energy requirements of the process. Besides, hydrogen-based energy efficiencies increase with increasing temperature while first increases to a medium value of steam to biomass ratio (2.0), adsorbent to biomass ratio (1.0) and fluidization velocity (0.21 m/s) followed by a slight decrease (or remains unchanged). The integrated catalytic adsorption steam gasification is found to be a high energy consuming process and thus, waste heat integration needs to be implemented for feasible hydrogen production

  • 3.
    Naqvi, Muhammad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Dahlquist, E.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Yan, J.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden & Department of Chemical Engineering, Royal Institute of Technology (KTH), Sweden.
    Naqvi, S. R.
    School of Chemical & Materials Engineering, NUST, Pakistan.
    Nizami, A. S.
    Center of Excellence in Environmental Studies, King Abdulaziz University, Saudi Arabia.
    Salman, C. A.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Danish, M.
    State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Farooq, U.
    State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Rehan, M.
    Center of Excellence in Environmental Studies, King Abdulaziz University, Saudi Arabia.
    Khan, Z.
    Systems Power and Energy, School of Engineering, University of Glasgow, UK.
    Qureshi, A. S.
    Institute of Biotechnology and Genetic Engineering, 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.

  • 4. Naqvi, Muhammad
    et al.
    Yan, Jinyue
    Dahlquist, Erik
    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 (Refereed)
    Abstract [en]

    Black liquor gasification (BLG) for bio-fuel or electricity production at the modern pulp mills is a field in continuous evolution and the efforts are considerably driven by the climate change, fuel security, and renewable energy. This paper evaluates and compares two BLG systems for methanol production: (i) oxygen blown pressurized thermal BLG; and (ii) dry BLG with direct causticization, which have been regarded as the most potential technology candidates for the future deployment. A key objective is to assess integration possibilities of BLG technologies with the reference Kraft pulp mill producing 1000 air dried tonnes (ADt) pulp/day replacing conventional recovery cycle. The study was performed to 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 methanol from 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 substantially higher in pressurized BLG system (117 million tonnes/year CO2 reductions) as compared to dry BLG system (45 million tonnes/year CO2 reductions). However, the dry BLG system with direct causticization shows 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, dimethyl ether (DME) and bio-methane, has also been discussed

  • 5.
    Naqvi, Muhammad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Yan, Jinyue
    Dahlquist, Erik
    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.

  • 6.
    Naqvi, Muhammad
    et al.
    Mälardalens högskola.
    Yan, Jinyue
    Mälardalens högskola; KTH.
    Dahlquist, Erik
    Mälardalens högskola.
    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 generation 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 generation. 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 capacity 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 comparison 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 electricity tariff. Moreover, the challenges for the implementation of the real off-grid electricity generation plant are discussed. (C) 2017 Elsevier Ltd. All rights reserved.

  • 7.
    Rezk, Kamal
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Forsberg, Jan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Geometry development of the internal duct system of a heat pump tumble dryer based on fluid mechanic parameters from a CFD software2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 5, p. 1596-1605Article in journal (Refereed)
    Abstract [en]

    One aspect of reducing the energy consumption of a household tumble dryer is to reduce the pressure drop of the circulating air in the internal duct system. It is, however, costly and time consuming to design several prototypes for airflow measurements. In this paper, several fluid mechanic parameters in a partial model of the internal duct system of a tumble dryer have been studied in the CFD software Comsol MultiPhysics. The purpose was to establish a numerically based design process, where the design is conducted based on visual analysis of air velocity and vorticity, and two design criteria. The geometry design was conducted by a CAD-engineer, which was the counterpart of this project. In order to enable a successful design process, it was essential to establish a strong relation between fluid parameters and design criteria in order to share knowledge effectively with the CAD engineer. Two geometry modifications, based on a standard model, were conducted on the duct. Based on the design criteria, the pressure drop and the non-uniformity coefficient of the outlet airflow, the second modification (Modification 2) represents an improvement as the pressure drop is reduced by 23% and the uniformity at the outflow section is increased by 3%.

  • 8.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Mälardalen University.
    Thorin, Eva
    Mälardalen University.
    Yan, Jinyue
    Mälardalen University; KTH.
    Gasification process integration with existing combined heat and power plants for polygeneration of dimethyl ether or methanol: A detailed profitability analysis2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 226, p. 116-128Article in journal (Refereed)
    Abstract [en]

    Combustion of waste for cogeneration of heat and power is the most convenient and practical choice to carry out through combined heat and power (CHP) plants. But, seasonal variation in heat demand throughout the year affects the operation of CHP plants. This fluctuation in the CHP operation cause less annual operating hours for the plant equipment and is also not profitable for stakeholders. This study aims to assess the technical potential of integrated gasification process with existing CHP plants for either dimethyl ether (DME) or methanol production through refuse-derived fuel (RDF). Process integration considers that the CHP plant provides the necessary heat for biofuel synthesis during off-peak hours. Mass and heat integration methods are used to develop and simulate the polygeneration processes for heat, power, and biofuel production. Both technical and economic indicators are reported and compared to assess the potential for both biofuels through process integration. Annual operation data of a real CHP plant has been extracted to evaluate the integrated processes. A flexible gasification configuration is selected for the integrated approach i.e. CHP runs at full load to provide the heat demand and only the excess heat of CHP plant is utilized for biofuel production. The energetic efficiencies of the polygeneration systems are compared with the standalone systems. Technical analysis of process integration shows the enhancement of the operational capacity of CHP during off-peak hours and it can produce biofuels without compromising the annual heat demand. Production of methanol through process integration shows ∼67% energetic efficiency while methanol production gives ∼65%. The efficiencies are higher than standalone DME and methanol processes (51% and 53%, respectively) but lower than standalone CHP plant i.e. 81%, however the process integration increases the operating time of the CHP plant with more economic benefits. Economic analysis coupled with uncertainty analysis through Monte Carlo simulations shows that by integrating CHP with gasifier to produce biofuels is significantly profitable as compared with only heat and electricity production. But, DME as a potential product shows more economic benefits than methanol. The uncertainty analysis through Monte Carlo simulations shows that the profitable probability of DME as a product in future is also greater than methanol due to higher DME selling price. The uncertainty analysis further shows that prices of DME and methanol with waste biomass prices in future will have a greater impact on the economic performance of the proposed polygeneration process.

  • 9.
    Stawreberg, Lena
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nilsson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Potential Energy Savings Made by Using a Specific Control Strategy when Tumble Drying Small Loads2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 102, p. 484-491Article in journal (Refereed)
    Abstract [en]

    Tumble dryers manufactured today are optimised for their maximum capacity, i.e., 6–8 kg of dry load. An average washing load in ordinary households lands at between 2 and 3.5 kg dry load, which implies that the drying load is even smaller. The energy efficiency decreases with reduced drying load. The aim of this study is to establish a mathematical model for studying alternative control strategies for the venting tumble dryer in order to increase the energy efficiency of drying small loads. Two series of test runs were performed: the first series with three different drying loads was used as reference tests for validation of the mathematical model, and the second series was performed with airflow reduction. The model shows good agreement with the test runs. Two control strategies were tested using the model on the smallest drying load. By lowering the heat supply to the heater and by reducing the airflow, the energy efficiency increases by 6% in a small load drying cycle. It was not possible, however, for the investigated dryer, to reach the same energy efficiency for small loads as for the maximum drying load by using a control strategy.

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