| 1. |
- Ahmad, Waqar, et al.
(författare)
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Investigation of different configurations of alumina packed bed reactor for coke free conversion of benzene
- 2024
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Ingår i: Chemical engineering research & design. - : Elsevier. - 0263-8762 .- 1744-3563. ; 201, s. 433-445
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Tidskriftsartikel (refereegranskat)abstract
- Conversion of producer gas tar without coke generation is a great challenge. This study investigates conversion of tar model benzene using different configurations of highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 0C. The configurations comprised of different positions (relative to top (P1), center (P2) and bottom (P3) of reactor furnace), heights (5, 13 and 25 cm) and particles sizes (0.5, 3 and 5 mm) of alumina packed bed. Steam and CO2 were used as reforming media for tested benzene concentrations (0.4–1.8 vol%). The results showed benzene conversions of 48–91% with negligible steady thin coke generation using a packed bed (height: 25 cm, particles size: 3 mm) at P1. Whereas, relative high benzene conversions of 63–93 and 68–95% at P2 and P3 respectively with unsteady thick coke generation at benzene concentrations greater than 0.4 vol% increased differential upstream pressures (DUPs) of beds. Similar unsteady coke generation at benzene concentrations greater than 0.8 vol% and temperature of 1100 0C was observed with packed beds of heights of 5 and 13 cm, and particles size of 0.5 mm at P1. Generation of unsteady coke with condensed structure as evidenced by its characterization was attributable to increased benzene polymerization and reduced bed surface gasification reactions due to improperly installed packed bed. Developed kinetic model predicted well the generated coke. As conclusion, properly installed alumina packed bed pertaining to tar concentration and other experimental conditions may inhibit coke generation during tar conversion.
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| 2. |
- Albero Caro, Jesus, et al.
(författare)
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Semibatch reaction crystallization of salicylic acid
- 2014
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 92:3, s. 522-533
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Tidskriftsartikel (refereegranskat)abstract
- Reaction crystallization of salicylic acid has been investigated by experiments and modeling. In the experimental work, dilute hydrochloric acid has been added to an agitated aqueous solution of sodium salicylate in 1 L scale, and product crystals have been characterized by image analysis. The results show that the product crystal number mean size at first increases with increasing agitation rate but then gradually decreases again at further increase in stirring rate. At lower stirring rate, larger crystals are obtained when the feeding point is located close to the agitator instead of being located out in the bulk solution. The mean crystal size increases with decreasing feeding rate and with decreasing reactant concentrations. There is a decrease in mean size with increasing feed pipe diameter. These trends in the experimental results show great similarity with previous results on benzoic acid. The experimental results have been examined by a population balance model accounting for meso and micro mixing, and crystal nucleation and growth rate dispersion. It is found that the crystallization kinetic parameter estimation is quite complex, and the objective function hyper surface contains many different minima. Hence, parameter estimation has to rely on a combination of mathematical optimization strategies and a scientific understanding of the physical meaning of the parameters and their relation to current theories. As opposed to our previous work on benzoic acid, it has not been possible to find a set of kinetic parameters that provides for a good description of all experimental data.
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| 3. |
- Arvidsson, Maria, 1984, et al.
(författare)
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Comparative thermodynamic analysis of biomass gasification-based light olefin production using methanol or DME as the platform chemical
- 2016
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 115, s. 182-194
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates and compares the thermodynamic performance of alternative platform chemicals for the production of light olefins (i.e., ethylene, propylene, and mixed butylenes) via gasification of lignocellulosic biomass (forest residues). Two concepts based on the same general process layout are considered: (i) via methanol synthesis and methanol-to-olefins (MTO) synthesis; (ii) via direct dimethyl ether (DME) synthesis and DME-to-olefins (DTO) synthesis. The work is based on process models established in Aspen Plus to obtain mass and energy balances. Heat recovery targets for integration of a steam network for combined heat and power production are investigated using pinch analysis tools. The different process alternatives are compared in terms of energy efficiency. Additionally, to identify key process differences, the cold gas efficiency and carbon conversion from biomass feedstock to various intermediate products along the process value chain are compared. The results show that light olefins could be produced with an energy efficiency of approximately 52–54% (higher heating value (HHV) basis) using methanol and DME as platform chemicals. The two investigated concepts had similar cold gas efficiency along the process value chain and overall electricity balance. Accordingly, no significant thermodynamic difference could be identified for the two investigated cases. One interesting feature that is identified is that the same amount of the renewable carbon in the feedstock is lost, mainly as CO2, regardless of whether the methanol or DME route is adopted. The difference is where in the process value chain most of the CO2 is formed and removed.
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| 4. |
- Azis, Muhammad Mufti, 1983, et al.
(författare)
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On evaluation of synthetic and natural ilmenite using syngas as fuel in chemical-looping combustion (CLC)
- 2010
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 88:11A, s. 1505-1514
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-looping combustion (CLC) is a combustion technique where the CO2 produced is inherently separated fromthe rest of the flue gases with a considerably low energy penalty. For this reason, CLC has emerged as one of the moreattractive options to capture CO2 from fossil fuel combustion. When applying CLC with solid fuels, the use of a lowcost oxygen carrier is highly important, and one such low cost oxygen carrier is the mineral ilmenite. The currentwork investigates the reactivity of several ilmenites, some which are synthetically produced by freeze granulationand two natural minerals, one Norwegian ilmenite and one South African ilmenite.A laboratory fluidized bed reactor made of quartz was used to simulate a two reactor CLC system by alternatingthe reduction and oxidation phase. The fuel was syngas containing 50% CO and 50% H2. A mixture of 6 g of ilmenitewith 9 g inert quartz of diameter 125–180μm was exposed to a flow of 900mLn/min syngas in the reduction phase.During the oxidation phase, a 900mLn/min flow of 10% O2 diluted in N2 was used.The experimental results showed that all ilmenites give higher conversion of H2 than of CO. Generally, syntheticilmenites have better CO and H2 conversion than natural ilmenites and synthetic ilmenites prepared with an excessof Fe generally showed higher total conversion of CO than synthetic ilmenites with an excess of Ti. Most syntheticilmenites and the Norwegian ilmenite showed good fluidization properties during the experiments. However, for twoof the synthetically produced materials, and for the South African ilmenite, particle agglomerations were visible atthe end of the experiment.
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| 5. |
- Bebelis, S., et al.
(författare)
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Highlights during the development of electrochemical engineering
- 2013
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 91:10, s. 1998-2020
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Tidskriftsartikel (refereegranskat)abstract
- Over the last century, electrochemical engineering has contributed significantly to societal progress by enabling development of industrial processes for manufacturing chemicals, such as chlorine and the Nylon precursor adiponitrile, as well as a wide range of metals including aluminium and zinc. In 2011, ca. 17 M tonne Cu p.a. was electro-refined to 99.99%+ purity required by electrical and electronic engineering applications, such as for electrodepositing with exquisite resolution multi-layer inter-connections in microprocessors. Surface engineering is widely practised industrially e.g. to protect steels against corrosion e.g. by electroplating nickel or using more recent novel self-healing coatings. Complex shapes of hard alloys that are difficult to machine can be fabricated by selective dissolution in electrochemical machining processes. Electric fields can be used to drive desalination of brackish water for urban supplies and irrigation by electrodialysis with ion-permeable membranes; such fields can also be used in electrokinetic soil remediation processes. Rising concerns about the consequences of CO2 emissions has led to the rapidly increasing development and deployment of renewable energy systems, the intermittency of which can be mitigated by energy storage in e.g. redox flow batteries for stationary storage and novel lithium batteries with increased specific energies for powering electric vehicles, or when economically viable, in electrolyser-fuel cells. The interface between electrochemical technology and biotechnology is also developing rapidly, with applications such as microbial fuel cells.Some of these applications are reviewed, the challenges assessed and current trends elucidated in the very active area of Chemical Engineering bordering with material science and electrochemistry.
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| 6. |
- Bijok, Nicolaus, et al.
(författare)
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Chip scale modelling of the kraft pulping process by considering the heterogeneous nature of the lignocellulosic feedstock
- 2023
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 193, s. 13-27
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Tidskriftsartikel (refereegranskat)abstract
- This article focuses on a multiscale modelling approach to describe the delignification of softwood during the kraft pulping process. A framework for modelling the lignocellulosic feedstock on a fibre scale which considered the fundamental chemical components of wood as a distributed variable is re-assessed and extended to include chip-level phenomena such as diffusion limitations and initial component distributions within a softwood chip mixture. A new description of the wood chip is presented using a finite volume discretisation along one spatial dimension by simultaneously considering the anisotropic structural differences of the wood. Additionally, based on literature data, a distinction between the softwood chips' early- and latewood regions with their differences in densities and chemical composition is suggested. The presented model framework uses published sub-models for kinetics, diffusion etc. The validation and estimation of the remaining parameters are conducted from experimental data that quantifies the kappa number distribution of individual softwood fibres after kraft pulping. The investigation hypothesises a Gaussian distribution for the initial chemical component distribution within wood chips from a well-defined region. In contrast, a Log-normal distribution is used to describe the initial chemical distribution within a softwood chip mixture. The established sub-models for the kraft pulping process's kinetics and mass transfer phenomena could not predict the experimental data satisfactorily. However, modifying the sub-models by including a change in lignin reactivity and a temperature dependency of the lignin reactivity decline during the delignification progress could predict the essence of the observed experimental kappa number distribution.
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| 7. |
- Bouaifi, M., et al.
(författare)
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Experimental and numerical investigations of jet mixing in a multifunctional channel reactor: Passive and reactive systems
- 2004
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 82:A2, s. 274-283
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Tidskriftsartikel (refereegranskat)abstract
- Mixing of two liquids in a new multifunctional channel reactor developed by AlfaLaval has been studied both experimentally and through computational fluid dynamics (CFD). As the channels are quite narrow the Reynolds numbers are low and the bulk of the channel is within the turbulent boundary layer. This makes accurate a priori predictions of the flowfield difficult and experimental validation necessary. Particle image velocimetry (PIV) was used to measure the flowfield, whereas planar laser-induced fluorescence was used for a scalar concentration field. CFD simulations were performed with the commercial software Fluent 5.5. Different turbulence models were tested and compared with PIV. The best predictions were obtained with a low Reynolds boundary layer k-ε turbulence model. Mixing of a passive tracer, including mean concentration and concentration variance, was calculated with the turbulent mixer model of Baldyga. A reactive system with diazo coupling between 1-naphthols, 2-naphthols and diazotized sulphanilic acid was studied both experimentally and theoretically due to its sensitivity to mixing conditions. The interpolation model of Baldyga was used to predict the evolution of the species. Good agreement was found between simulations and experiments for both the flow field and the reactive system.
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| 8. |
- Darkins, Christopher Luke, et al.
(författare)
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Design of large-scale manufacturing of induced pluripotent stem cell derived cardiomyocytes
- 2014
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Ingår i: Chemical engineering research & design. - : Elsevier. - 0263-8762 .- 1744-3563. ; 92:6, s. 1142-1152
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Tidskriftsartikel (refereegranskat)abstract
- A new approach for design of large-scale manufacture of stem cell derived cells by using the biomechatronic methodology and computer-aided-design tools is described. The systematic conceptual design methodology for systems composed of active mechanical, electronic and biological components, here referred to as biomechatronics, is combined with the methodology for computer-aided design of bioprocesses. The objective has been to systematically investigate and compare by the combination of the methodologies what are favourable design alternatives in terms of equipment configuration and economic parameters. A demonstration case has been used for the manufacture of cardiomyocytes from human induced pluripotent stem cells. The results show how certain configurations are more favourable than others under given boundary conditions. The study indicates that the approach is possible to apply on other related bio-manufacturing systems.
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| 9. |
- Eng, Matthias, 1983, et al.
(författare)
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Influence of solids on macro-instabilities in a stirred tank
- 2012
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 90:8, s. 1052-1062
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Tidskriftsartikel (refereegranskat)abstract
- Measurements were conducted in a cylindrical tank stirred with a PBT in order to study the effect of varying amounts of suspended solids, up to 11.8% by volume, on the frequency and amplitude of macro-instabilities (MI). Solid glass particles of three different sizes were used in order to investigate the influence of the particle Stokes number. Measurements were made at 18 different locations in the vessel using laser Doppler anemometry (LDA) and were evaluated with the Lomb algorithm to obtain the frequency spectrum of the liquid flow. The results showed that the MI frequency is not influenced by the addition of solids. However, the MI amplitude was reduced by the addition of the solid phase although still detectable up to the highest concentration measured (11.8 vol.%). In the studied system there seems to be a difference dependent on the particle Stokes number.
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| 10. |
- Gamero, Rafael, et al.
(författare)
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The use of drying experiments in the study of the effective thermal conductivity in a solid containing a multicomponent liquid mixture
- 2012
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 90:11, s. 1765-1778
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Tidskriftsartikel (refereegranskat)abstract
- The effective thermal conductivity of a porous solid containing multicomponent liquid mixtures has been studied. To achieve this, the liquid composition, liquid content and temperature distributions have been measured in a cylindrical sample dried by convection from the open upper side and heated by contact with a hot source at the bottom side. A quasi-steady state reached at high source temperatures permits to calculate the total heat flux from temperatures measured on the surface and the gas stream. The simulations performed and compared with experimental data made it possible to estimate the adjusting geometric parameter of Krischer's model for the effective thermal conductivity. The effective thermal conductivity has been widely studied for two-phase systems, mostly with regard to thermal insulation elements. The calculation of this transport parameter includes the contribution to heat transfer of the evaporation–diffusion–condensation mechanism undergone by the multicomponent mixture. The influence of liquid composition and temperature on the thermal conductivity due to the evaporation–diffusion–condensation mechanism and the effective thermal conductivity is described. The results reveal that in this case the resistance to heat transfer seems to correspond to a parallel arrangement between the phases.
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