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  • 1.
    Carlsson, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Entrained flow black liquor gasification: detailed experiments and mathematical modelling2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Black liquor, a by-product from the Kraft pulping process is a highly viscous fluid consisting of approximately 30% water, 30 % alkali salts and 40 % combustible material. The alkali salts originating from the pulp making process need to be recovered in order for the pulp mill to be economical and to satisfy environmental regulation. Currently, the recovery takes place in a large boiler called Tomlinson recovery boiler named after its inventor. However, a more energy efficient way to recover the chemicals could be via gasification in a pressurized, entrained flow, high temperature gasifier. To demonstrate this technology a development plant (DP1) was built in 2005 by the technology vendor Chemrec. Since then, the plant has been running for more than 10 000 h and frequently been updated and optimized. As steps towards commercialization and scale–up different computational models of varying sophistication are used as design and optimization tools for the process. Still, the engineering tools can only provide sensible predictions if they are properly validated and verified. This licentiate thesis is concerned with validation of a comprehensive mathematical model based on Computational Fluid Dynamics (CFD) describing the gasification reactor and experimental investigations of the process characteristics in the DP1 gasifier. Paper A describes the system design and methodology for high temperature gas sampling during pressurized black liquor gasification. In this work a water-cooled gas sampling probe is installed in the hot part of the DP1 gasification reactor and several gas samples are withdrawn and analyzed. The experimentally obtained data in Paper A are then used as validation data for the CFD-model described in Paper B. In Paper C the obtained data from Paper A are thoroughly analyzed and the influence of reactor operation on producer gas composition is determined. In Paper D black liquor sprays from a gas assisted nozzle is experimentally investigated using high speed photography. Furthermore, the particle content in the cooled producer gas is measured using a particle sizing impactor. The obtained results in Paper D can be used to explain some of the observations in Paper A.

  • 2.
    Carlsson, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Large scale experiments and modeling of black liquor gasification2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biomass gasification could provide a basis for increased electricity and engine fuel production from a renewable source in the pulp and paper industry. This work focuses on the largest byproduct available at the pulp mills, black liquor. Black liquor is a mixture of spent cooking chemicals, dissolved lignin, dissolved carbohydrates and a small portion of inorganic compounds found in the wood. The conventional technology to recover the cooking chemicals and the chemical energy as heat is combustion in large boilers. Here, gasification could be an alternative, replacing or complementing the boilers. The gasification technology produces a combustible gas that can be cleaned to produce electricity in a gas turbine/engine or, be synthesized into valuable chemicals or liquid engine fuels. The technology has been demonstrated in development scale since 2005 and appears to be promising. Still, commercial plants have not yet been built. This thesis focuses on the understanding of the oxygen blown, pressurized, entrained flow, black liquor gasification technology. The main goals have been to increase the understanding about the dominating mechanisms in black liquor gasification and to develop an engineering tool that can be used to design and optimize, pressurized, entrained flow, black liquor gasifiers. To accomplish these goals gas samples were extracted from the gasification reactor using a gas sampling probe that was developed within this work. Gas samples were also collected downstream the quench located underneath the reactor and the results were compared. Finally, an existing numerical model was developed so it can predict the behavior of the black liquor gasifier within reasonable accuracy.Even though the actual mechanisms in the reactor and quench are very complex it appears that they can be described with relatively simple global mechanisms. The main gas components are dictated by the water gas shift reaction. At the outlet of the reactor the gas composition is not in global thermodynamic equilibrium. However, the main gas components are close to partial equilibrium whilst CH4 and H2S are not. Very little of the available CH4 is reformed outside the flame region and the primary consumption occurs in the flame through oxidation and reformation. When the system pressure is increased, H2S concentration in the gas will increase, the same will happen if the oxygen-fuel ratio is decreased. In the quench, the primary spray flow rate/load (mass flow of black liquor and oxygen) ratio has a critical value of about 0.6 below which the gas concentration of CO2, CO, and H2, is significantly changed. The H2/CO ratio can be changed from about 1.15 to 1.4 by changing the primary spray flow rate/load ratio. The mechanism is associated with the water gas shift reaction and the quenching rate of the gas stream. The computational fluid dynamics reactor model predicts most of the trends when operating conditions are changed and is in good agreement with the experimental results with respect to gas composition and char carbon conversion.

  • 3.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grönberg, Carola
    Energy Technology Centre, Piteå.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Risberg, Mikael
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhrman, Olov
    Spatially resolved measurements of gas composition in a pressurised black liquor gasifier2009In: Environmental Progress & Sustainable Energy, ISSN 1944-7442, E-ISSN 1944-7450, Vol. 28, no 3, p. 316-323Article in journal (Refereed)
    Abstract [en]

    Black liquor gasification is a new process for recovery of energy and chemicals in black liquor from the Kraft pulping process. The process can be combined with catalytic conversion of syngas into motor fuels. The potential for motor fuel production from black liquor in Sweden is to replace about 25% of the current consumption of gasoline and diesel. For Finland the figure is even higher while for Canada it is about 14% and for the USA about 2%.

  • 4.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Iisa, Kristiina
    National Renewable Energy Laboratory.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Computational fluid dynamics simulations of raw gas composition from a black liquor gasifier: comparison with experiments2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 9, p. 4122-4128Article in journal (Refereed)
    Abstract [en]

    Pressurized entrained flow high temperature black liquor gasification can be used as a complement or a substitute to the Tomlinson boiler used in the chemical recovery process at kraft pulp mills. The technology has been proven on the development scale, but there are still no full scale plants. This work is intended to aid in the development by providing computational tools that can be used in scale up of the existing technology. In this work, an existing computational fluid dynamics (CFD) model describing the gasification reactor is refined. First, one-dimensional (1D) plug flow reactor calculations with a comprehensive reaction mechanism are performed to judge the validity of the global homogeneous reaction mechanism used in the CFD simulations in the temperature range considered. On the basis of the results from the comparison, an extinction temperature modification of the steam-methane reforming reaction was introduced in the CFD model. An extinction temperature of 1400 K was determined to give the best overall agreement between the two models. Next, the results from simulations of the flow in a 3 MW pilot gasifier with the updated CFD model are compared to experimental results in which pressure, oxygen to black liquor equivalence ratio, and residence time have been varied. The results show that the updated CFD model can predict the main gas components (H2, CO, CO2) within an absolute error of 2.5 mol %. CH4 can be predicted within an absolute error of 1 mol %, and most of the trends when process conditions are varied are captured by the model.

  • 5.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lycksam, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Iisa, Kristiina
    National Renewable Energy Laboratory, Golden, Colorado.
    High-speed imaging of biomass particles heated with a laser2013In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 103, p. 278-286Article in journal (Refereed)
    Abstract [en]

    In this work two types of lignocellulosic biomass particles, European spruce and American hardwood (particle sizes from 100 μm to 500 μm) were pyrolysed with a continuous wave 2 W Nd:YAG laser. Simultaneously a high-speed camera was used to capture the behavior of the biomass particle as it was heated for about 0.1 s. Cover glasses were used as a sample holder which allowed for light microscope studies after the heating. Since the cover glasses are not initially heated by the laser, vapors from the biomass particle are quenched on the glass within about 1 particle diameter from the initial particle. Image processing was used to track the contour of the biomass particle and the enclosed area of the contour was calculated for each frame.The main observations are: There is a significant difference between how much surface energy is needed to pyrolyses the spruce (about 75% more) compared to the hardwood. The oil-like substance which appeared on the glass during the experiment is solid at room temperature and shows different levels of transparency. A fraction of this substance is water soluble. A brownish coat is seen on the unreacted biomass. The biomass showed insignificant swelling as it was heated. The biomass particle appears to melt and boil at the front that is formed between the laser beam and the biomass particle. The part of the particle that is not subjected to the laser beam seems to be unaffected.

  • 6.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Furusjö, Erik
    Chemrec.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Black liquor gasification: CFD model predictions compared with measurements2010In: 2010 International Chemical Recovery Conference Proceedings, Norcross, GA: TAPPI Press, 2010, Vol. 2, p. 160-171Conference paper (Refereed)
  • 7.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Furusjö, Erik
    Chemrec.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Experiments and mathematical models of black liquor gasification: influence of minor gas components on temperature, gas composition, and fixed carbon conversion2010In: TAPPI Journal, ISSN 0734-1415, Vol. 9, no 9, p. 15-24Article in journal (Refereed)
    Abstract [en]

    In this work, predictions from a reacting Computational Fluid Dynamics (CFD) model of a gasification reactor are compared to experimentally obtained data from an industrial pressurized black liquor gasification plant. The data consists of gas samples taken from the hot part of the gasification reactor using a water cooled sampling probe. During the considered experimental campaign, the oxygen-to-black liquor equivalence ratio (λ) was varied in three increments, which resulted in a change in reactor temperature and gas composition. The presented numerical study consists of CFD and thermodynamic equilibrium calculations in the considered λ-range using boundary conditions obtained from the experimental campaign. Specifically, the influence of methane concentration on the gas composition is evaluated using both CFD and thermodynamic equilibrium. The results show that the main gas components (H2, CO, CO2) can be predicted within a relative error of 5% using CFD if the modeled release of H2S and CH4 are specified a priori. In addition, the calculations also show that the methane concentration has large influence on the reactor outlet temperature and final carbon conversion.

  • 8.
    Carlsson, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Comparison and validation of gas phase reaction schemes for black liquor gasification modeling2008In: Conference Proceedings 2008 AiChE annual meeting: Advances in gasification research, 2008Conference paper (Other academic)
    Abstract [en]

    Pressurized Entrained-flow High Temperature Black Liquor Gasification (PEHT-BLG) is a potential substitute or complement to the recovery boiler traditionally used for the recovery of chemicals and energy in black liquor in the Kraft pulping process. Black liquor consists of roughly 30 % moisture, 35 % inorganic pulping chemicals and 35 % combustible material (i.e. lignin). The PEHT-BLG technology can give an increase in total energy efficiency of the mill and provide new products with high added value, such as green motor fuels. The main parts of the recovery unit in the process are; a slagging refractory lined entrained-flow gasification reactor, with a gas assisted burner nozzle producing small black liquor droplets, used for direct gasification of the black liquor at about 1000 °C to produce a ‘raw' syngas and a liquid smelt containing mainly Na2CO3 and Na2S; a quench cooler beneath the reactor where the product gas and smelt are separated and the smelt is dissolved in water forming green liquor; a counter current condenser (CCC) that cools the syngas and condenses water vapor and any volatile and tar species that may be present. The heat recovered from the gas condensation is used to generate low/medium pressure steam that can be used in the pulp and paper process. Furthermore, the chemicals in the green liquor are recovered as cooking chemicals in the downstream processing. Due to lack of demonstration of long term operation of the technology, a development (pilot) plant for PEHT-BLG (named DP-1) with a capacity of 20 tones dry solids/24h is in operation by the technology vendor Chemrec AB at the Energy Technology Centre in Piteå, Sweden. An important tool for reduction of the technical risk associated with scale up of new technology is a comprehensive CFD model for the PEHT-BLG reactor. The current model includes drying, pyrolysis, char gasification and smelt formation of black liquor droplets as well as a simplified gas phase reaction mechanism. The current model has been validated against the outlet gas composition after the Counter Current Condenser (CCC). The model predicted a CO / CO2 ratio that was approximately 50% higher compared to the measurements. However, it is possible that the well known water-gas shift reaction is active in the quench and this could explain that the experimentally determined gas composition after the CCC differs from the computational results at the outlet from the hot zone. Recently, in-situ measurements have been performed in the DP-1 reactor and a further validation of the model has been made possible. The measurements have been performed by sampling gas with a water-cooled suction probe from the lower part of the hot zone, followed by offline gas analyses. The present paper investigates the difference between the current CFD-model and a modified version with an additional CO + O2 reaction added to the simplified gas phase reaction scheme. The simulation results are compared against measurements obtained by the gas sampling probe in the DP-1 reactor. The results suggest that by implementing the additional CO + O2 reaction local flame temperature was increased significantly. However, the effect on volume average and outlet gas temperature was minimal.The results also showed that the CO + O2 reaction had very little effect on outlet gas composition when the reaction was implemented in the PEHT-BLG-CFD model

  • 9. Carlsson, Per
    et al.
    Wiinikka, Henrik
    Energy Technology Centre, Piteå.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Grönberg, Carola
    Energy Technology Centre, Piteå.
    Pettersson, Esbjörn
    Energy Technology Centre, Piteå.
    Lidman, Marcus
    Energy Technology Centre, Piteå.
    Gebart, Rikard
    Energy Technology Centre, Piteå.
    Experimental investigation of an industrial scale black liquor gasifier: 1. Influence of reactor operation parameters on product gas composition2010In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 89, no 12, p. 4025-4034Article in journal (Refereed)
    Abstract [en]

    A novel technology to mitigate the climate changes and improve energy security is Pressurized Entrained flow High Temperature Black Liquor Gasification (PEHT-BLG) in combination with an efficient fuel synthesis using the resulting syngas. In order to optimise the technology for use in a pulp and paper mill based biorefinery, it is of great importance to understand how the operational parameters of the gasifier affect the product gas composition. The present paper is based on experiments where gas samples were withdrawn from the hot part of a 3 MW entrained flow pressurized black liquor gasifier of semi industrial scale using a high temperature gas sampling system. Specifically, the influence of process conditions on product gas composition (CO2, CO, H2, CH4, H2S, and COS) were examined by systematically varying the operational parameters: system pressure, oxygen to black liquor equivalence ratio, black liquor flow rate to pressure ratio and black liquor pre-heat temperature. Due to the harsh environment inside the gasification reactor, gas sampling is a challenging task. However, for the purpose of the current study, a specially designed high temperature gas sampling system was successfully developed and used. The results, obtained from two separate experimental campaigns, show that all of the investigated operational parameters have a significant influence on the product gas composition and present valuable information about to the process characteristics.

  • 10.
    Gebart, Rikard
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Marklund, M.
    Energy Technology Centre, Piteå.
    Carlsson, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grönberg, C.
    Weiland, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Johansson, A-C
    Öhrman, Olov
    Recent advances in the understanding of pressurized black liquor gasification2011In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 45, no 7-8, p. 521-526Article in journal (Refereed)
  • 11.
    Wiinikka, Henrik
    et al.
    Energy Technology Centre, Piteå.
    Carlsson, Per
    Granberg, Fredrik
    Chemrec.
    Löfström, Johan
    Chemrec.
    Marklund, Magnus
    Energy Technology Centre, Piteå.
    Tegman, Ragnar
    Chemrec.
    Lindblom, Mats
    Chemrec.
    Gebart, Rikard
    Swerea SICOMP AB, Box 271, 941 26, Piteå.
    Design and methodology of a high temperature gas sampling system for pressurized black liquor gasification2010In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 89, no 9, p. 2583-2591Article in journal (Refereed)
    Abstract [en]

    This paper describes the system design and methodology for high temperature gas sampling during pressurized black liquor gasification. The motivation for developing a system that can withstand the harsh conditions in the reactor part of the gasifier (30 bar, 1000 °C, reducing conditions and corrosive environment) comes from an ambition to better understand the various stages in the conversion of the fuel (black liquor) and provide spatially resolved data of the gas composition inside the gasification reactor. Important components in the high temperature sampling system which are all described in detail in the paper, are the syngas sampling line, nitrogen purging system, water cooling line and an aerodynamic quench probe with an anti-clogging shield. Several measurement campaigns have been conducted in the gasifier where the concentration of CO2, CO, H2, CH4, H2S, and COS close to the outlet of the hot reactor have been measured with the high temperature gas sampling system. The results showed that the repeatability of the measured gas composition was excellent and that significant effects on the gas composition from different operating parameters of the gasifier could be found.

  • 12.
    Wiinikka, Henrik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Weiland, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Pettersson, Esbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Öhrman, Olov
    Carlsson, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Stjernberg, Jesper
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Characterisation of submicron particles produced during oxygen blown entrained flow gasification of biomass2014In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 161, no 7, p. 1923-1934Article in journal (Refereed)
    Abstract [en]

    In this paper submicron particles sampled after the quench during 200 kW, 2 bar(a) pressurised, oxygen blown gasification of three biomass fuels, pure stem wood of pine and spruce, bark from spruce and a bark mixture, have been characterised with respect to particle size distribution with a low pressure cascade impactor. The particles were also characterised for morphology and elemental composition by a combination of scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and high resolution transmission electron microscopy/energy dispersive spectroscopy/selected area electron diffraction pattern (HRTEM/EDS/SAED) techniques. The resulting particle concentration in the syngas after the quench varied between 46 and 289 mg/Nm3 consisting of both carbon and easily volatile ash forming element significantly depending on the fuel ash content. Several different types of particles could be identified from classic soot particles to pure metallic zinc particles depending on the individual particle relation of carbon and ash forming elements. The results also indicate that ash forming elements and especially zinc interacts in the soot formation process creating a particle with shape and microstructure significantly different from a classical soot particle.

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