Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 2Citation - Scopus: 2Further Developments of the Extended Quadrature Method of Moments To Solve Population Balance Equations(Cell Press, 2023) Turan, Meltem; Dutta, AbhishekDeveloping numerical methods to solve polydispersed flows using a Population Balance Equation (PBE) is an active research topic with wide engineering applications. The Extended Quadrature Method of Moments (EQMOM) approximates the number density as a positive mixture of Kernel Density Functions (KDFs) that allows physical source terms in the PBEs to compute continuous or point-wise form according to the moments. The moment-inversion procedure used in EQMOM has limitations such as the inability to calculate certain roots even if it is defined, absence of consistent result when multiple roots exist or when the roots are nearly equal. To address these limitations, the study proposes a modification of the moment-inversion procedure to solve the PBE based on the proposed Halley-Ridder (H-R) method. Although there is no significant improvement in the extent of variability relative to the mean of the tested shape parameter cr values, an increase in the number of floating point operations (FLOPS) is observed which the proposed algorithm responds in limitations mentioned above. The total number of FLOPS for all the kernels used for the approximation increased by around 30%. This is an improvement towards the development of a more reliable and robust moment-inversion procedure.Conference Object Numerical Study on the Mixing Characteristics in the Argon Oxygen Decarburization Process(Association for Iron and Steel Technology, AISTECH, 2022) Cheng, Zhongfu; Wang, Yannan; Dutta, Abhishek; Blanpain, Bart; Guo, Muxing; Malfliet, AnneliesThe argon-oxygen decarburization (AOD) process is a crucial refining method in modern stainless steel production. It has been widely used to remove C in the past few decades [1, 2]. The AOD converter can provide excellent mixing conditions through turbulent stirring using submerged tuyeres. In the AOD process, the flow characteristics in the bath have a significant influence on the mass transport, momentum exchange and heat transfer, which are closely linked with the gas-metal reaction kinetics and the refining efficiency. A deep understanding of jet behavior, bubble flow characteristics and mixing efficiency facilitates further optimization of the decarburization and desulfurization operations. This will increase the AOD productivity and lower its energy and material consumption as well as the manufacturing cost.Article Citation - WoS: 4Citation - Scopus: 5Numerical Study of Fluid Flow and Mixing in the Argon Oxygen Decarburization (aod) Process(Iron and Steel Institute of Japan, 2023) Cheng, Zhongfu; Wang, Yannan; Dutta, Abhishek; Blanpain, Bart; Guo, Muxing; Malfliet, AnneliesA three-dimensional (3D) model has been developed based on the Eulerian multiphase flow approach to investigate the fluid flow behavior and mixing efficiency in the multi-tuyere AOD process. The interphase forces, including drag force, lift force, virtual force, turbulent dispersion force, and wall lubrication force, were incorporated into this model. The model was used to simulate six-tuyere and seven-tuyere AOD processes. The phenomena of multi-jet penetration, bubble plume merging, 3D turbulent flow and mixing characteristics were considered. The results indicate that the bubble plume merging occurs in the upper part of the liquid bath, forming a typical plume cluster. The predicted penetration length for a single tuyere jet agrees well with the previous work. For the multi-jet system, the side jets penetrate deeper than the inside ones. The six-tuyere AOD has a good flow condition in the center of the liquid bath, while the seven-tuyere AOD has a better flow pattern in the sidewall region and the lower bath. Overall, the seven-tuyere AOD performs better in mixing efficiency than the six-tuyere AOD under the same gas flow rate. These findings increase the understanding of the AOD process, allowing further optimization of process parameters. This model can be further extended to incorporate the thermochemical reactions into the modeling of the AOD reactor.Article Citation - WoS: 3Citation - Scopus: 3Numerical Study of Electrostatic Desalting: a Detailed Parametric Study(MDPI, 2022) Ramirez-Argaez, Marco A.; Abreú-López, Diego; Gracia-Fadrique, Jesús; Dutta, AbhishekA systematic process analysis was conducted to study the effect of the main variables in an industrial electrostatic desalter, such as electric field intensity, wash water content, droplet size, and oil viscosity, on the efficiency of the separation of water from oil. The analysis was assessed through an already published and validated CFD multiphase numerical model that considers the expression of the frequency of collisions as a function of the mentioned process variables. Additionally, the study allowed the formal optimization exercise of the operation to maximize the separation efficiency. The most significant variables were the initial water content and the electric field intensity, while the temperature (oil viscosity) had an effect to a lower extent. An increase in the electric field and temperature and a decrease in the water content improved the water separation from oil. Optimum values suggested from the factorial experimental design and the optimization implemented in this work indicated the use of an electric field of 3 kV/cm, water content of 3%, and an oil viscosity of 0.017 kg/ms. At the same time, the droplet size showed no significant effect under the conditions explored in this work.Article Citation - WoS: 12Citation - Scopus: 14Extraction of Monophenols and Fractionation of Depolymerized Lignin Oil With Nanofiltration Membranes(Elsevier, 2023) Croes, Tim; Dutta, Abhishek; De Bie, Robin; Van Aelst, Korneel; Sels, Bert; Van der Bruggen, BartOrganic solvent nanofiltration membranes were employed to fractionate birch derived reductive catalytic fractionated (RCF) lignin oil. This lignin oil is highly depolymerized, with most, if not all chemical compounds lighter than 3 kDa. Sixteen commercially available membranes were investigated for the fractionation, in combination with methanol and ethyl acetate as solvents. Membrane performances were quantified using Gaussian fits of gel permeation chromatograms and separation factor calculations. The separation factor was found to be primarily based on affinities instead of size-exclusion. The silicon-based membranes from Borsig (Germany) and PuraMem S600 from Evonik (UK) proved best at separating lignin into different functional fractions, showing monomer separation factors up to 7.4 and providing a permeate fraction with 88 % phenolic monomer purity. These membranes were further examined in batch diafiltration and two-stage filtration. This increased the separation factor from 7.4 to 25.4, and the monomer purity of the permeate to 95 %, proving that membrane purification of the lignin-derived monophenols is technically feasible.Article Citation - WoS: 13Citation - Scopus: 17Characterization and Beneficiation of Ethiopian Kaolin for Use in Fabrication of Ceramic Membrane(IOP Publishing, 2021) Zewdie, Tsegahun Mekonnen; Prihatiningtyas, Indah; Dutta, Abhishek; Habtu, Nigus Gabbiye; Van der Bruggen, BartKaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt% SiO2, 24.9 wt% Al2O3, 2.4 wt% Fe2O3, and 8.22 wt% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt%) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120 degrees C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4% was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low-cost kaolin-based ceramic membrane. After firing at 1100 degrees C the ceramic membrane was found to have a mass loss of 11.04 +/- 0.05%, water absorption of 8.9 +/- 0.4%, linear shrinkage of 14.5 +/- 0.05%. It was demonstrated to be chemically stable, having less than 3% mass loss in acid solution, and less than 1% mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.Article Citation - WoS: 6Citation - Scopus: 6Mathematical Modelling of the Liquid/Liquid Mass Transfer Behaviour in Gas Stirred Ladles(Taylor & Francis, 2022) Zhang, Han; Conejo, Alberto N.; Dutta, Abhishek; Ramírez-Argáez, Marco A.; Yan, HanA three-dimensional numerical model consistent with physical simulations (water/oil/thymol) has been developed to explore the mass transfer behaviour of sulphur. Euler-Lagrangian and Euler-Euler, were applied to simulate the multiphase flow; compared with experimental data, the Euler-Euler method was more accurate. The small eddy model was used for mass transfer calculations. As a new type of bottom stirring scheme, the effect of central-eccentric parallel injection on mass transfer was investigated. Moving the eccentric nozzle towards the sidewall or increasing the number of eccentric nozzles decreases the mass transfer rate at a constant total gas flow rate. The mass transfer rate increases with increasing central gas flow rate under the differential flow bottom stirring scheme. The single-nozzle central injection is still considered the most superior bottom-blowing scheme. The bubble diameter has an insignificant effect on the liquid–liquid mass transfer. The mass transfer rate of thymol is weakly accelerated with increasing bubble diameter.Article Citation - WoS: 5Citation - Scopus: 5Flat sheet metakaolin ceramic membrane for water desalination via direct contact membrane distillation(IWA Publishing, 2022) Zewdie, Tsegahun Mekonnen; Habtu, Nigus Gabbiye; Dutta, Abhishek; Van der Bruggen, BartHydrophobic metakaolin-based flat sheet membrane was developed via phase inversion and sintering technique and modified through 1H,1H,2H,2H-perfluorooctyltriethoxysilane grafting agents. The prepared membrane was characterized by different techniques such as XRD, FTIR, SEM, contact angle, porosity, and mechanical strength. Their results indicated that the wettability, structural, and mechanical properties of the prepared membrane confirm the suitability of the material for membrane distillation (MD) application. The prepared metakaolin-based flat sheet membrane acquired hydrophobic properties after surface modification with the water contact angle values of 113.2° to 143.3°. Afterward, the membrane performance was tested for different sodium chloride aqueous solutions (synthetic seawater) and various operating parameters (feed temperature, feed flow rate) using direct contact membrane distillation (DCMD). Based on the findings, the prepared membrane at metakaolin loading of 45 wt.% and sintered at 1,300 °C was achieved the best performance with >95% salt rejection and permeate flux of 6.58 + 0.3 L/m2 · h at feed temperature of 80 °C, feed concentration of 35 g/L, and feed flow rate of 60 L/h. It can be con-cluded that further optimization of membrane porosity, mechanical, and surface properties is required to maximize the permeate flux and salt rejection.Article Citation - WoS: 11Citation - Scopus: 12Numerical Modelling Assisted Design of a Compact Ultrafiltration (uf) Flat Sheet Membrane Module(MDPI, 2021) Bopape, Mokgadi F.; Van Geel, Tim; Dutta, Abhishek; Van der Bruggen, Bart; Onyango, Maurice StephenThe increasing adoption of ultra-low pressure (ULP) membrane systems for drinking water treatment in small rural communities is currently hindered by a limited number of studies on module design. Detailed knowledge on both intrinsic membrane transport properties and fluid hydrodynamics within the module is essential in understanding ULP performance prediction, mass transfer analysis for scaling-up between lab-scale and industrial scale research. In comparison to hollow fiber membranes, flat sheet membranes present certain advantages such as simple manufacture, sheet replacement for cleaning, moderate packing density and low to moderate energy usage. In the present case study, a numerical model using computational fluid dynamics (CFD) of a novel custom flat sheet membrane module has been designed in 3D to predict fluid flow conditions. The permeate flux through the membrane decreased with an increase in spacer curviness from 2.81 L/m(2)h for no (0%) curviness to 2.73 L/m(2)h for full (100%) curviness. A parametric analysis on configuration variables was carried out to determine the optimum design variables and no significant influence of spacer inflow or outflow thickness on the fluid flow were observed. The numerical model provides the necessary information on the role of geometrical and operating parameters for fabricating a module prototype where access to technical expertise is limited.Article Citation - WoS: 31Citation - Scopus: 38Resource Recovery From and Management of Wastewater in Rural South Africa: Possibilities and Practices(Elsevier, 2021) Montwedi, Masego; Munyaradzi, Mujuru; Pinoy, Luc; Dutta, Abhishek; Ikumi, David S.; Motoasca, Emilia; Van der Bruggen, BartThe continuous reduction in water resource availability is one of the major global societal challenges. Wastewater treatment plants (WWTP) play an important role in this, as they can provide water recovery. Furthermore, effective sanitation services lead to a significant reduction of health risks and protect the environment. However, WWTPs consume large amounts of energy to comply with discharge standards. At the same time, wastewater contains resources, which can be recovered for secondary uses, if treated properly. This is particularly useful for rural South Africa where challenges associated with water-based pollution, declining nutrients and water shortage, require a paradigm shift. This involves the transition of wastewater treatment plants into water, sanitation and resource (nutrients and energy) recovery facilities, leading further to social, economic and environmental sustainability. This process will involve the implementation of engineering tools for predictive modelling of the waste resource recovery systems. This review identifies the conceptual need for such a systematic shift from wastewater treatment to waste recovery facilities in rural South Africa. The targeted impact is to promote and help the uptake of the conversion of wastewater treatment systems into low cost and environmentally sustainable water and resource recovery facilities. Overall, the outlook is positive for the future use of these systems in South-Africa.