Atul Bansode
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2 records found
1
Master thesis
(2025)
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A. Venkataramanan, J.T. Padding, R. Ramesh, W. de Jong, R.M. Manila, Atul Bansode
The transition toward a circular economy necessitates efficient energy recovery technologies for biomass and plastic waste. Fluidized bed reactors (FBRs) provide excellent gas–solid mixing and thermal efficiency; however, their scale-up is often limited by complex hydrodynamics. This study examines the hydrodynamics of a scaled-down tapered bubbling fluidized bed (BFB) through combined experimental and numerical analyses. A scaling methodology based on Glicksman’s inertial law was employed to design a small-scale reactor that replicates the flow characteristics of a large facility. Experimental investigations using γ-ray computed tomography (CT) and radiographic scans were conducted to quantify solid fraction distributions and visualize bed expansion under varying gas velocities, revealing axial variations in particle-phase packing and gas–solid interactions. Parallel computational fluid dynamics (CFD) simulations, carried out in Ansys Fluent using a two-fluid Euler–Euler framework with the kinetic theory of granular flow (KTGF), successfully captured the onset of fluidization and the
evolution of gas inlet jets along the axial height. Nonetheless, extending the simulation runs to longer physical times would provide deeper insights into the underlying flow physics. ...
evolution of gas inlet jets along the axial height. Nonetheless, extending the simulation runs to longer physical times would provide deeper insights into the underlying flow physics. ...
The transition toward a circular economy necessitates efficient energy recovery technologies for biomass and plastic waste. Fluidized bed reactors (FBRs) provide excellent gas–solid mixing and thermal efficiency; however, their scale-up is often limited by complex hydrodynamics. This study examines the hydrodynamics of a scaled-down tapered bubbling fluidized bed (BFB) through combined experimental and numerical analyses. A scaling methodology based on Glicksman’s inertial law was employed to design a small-scale reactor that replicates the flow characteristics of a large facility. Experimental investigations using γ-ray computed tomography (CT) and radiographic scans were conducted to quantify solid fraction distributions and visualize bed expansion under varying gas velocities, revealing axial variations in particle-phase packing and gas–solid interactions. Parallel computational fluid dynamics (CFD) simulations, carried out in Ansys Fluent using a two-fluid Euler–Euler framework with the kinetic theory of granular flow (KTGF), successfully captured the onset of fluidization and the
evolution of gas inlet jets along the axial height. Nonetheless, extending the simulation runs to longer physical times would provide deeper insights into the underlying flow physics.
evolution of gas inlet jets along the axial height. Nonetheless, extending the simulation runs to longer physical times would provide deeper insights into the underlying flow physics.
A novel activated carbon-iron composite material has been developed as an adsorbent for water treatment. Due to its activated carbon (AC) content, the material could be used to remove pollutants such as organic micropollutants (OMP). Fast AC bed exhaustion makes adsorption a cost-intensive solution. Regeneration of AC is done off-site and requires transport and high energy consumption for heat treatment. Due to the iron and graphite content of the novel adsorbent, catalytic regeneration could allow for in-situ regeneration. This property would present a major advantage over common AC. Regeneration could potentially be realized by applying an electric current across an exhausted bed of this adsorbent. Such a setup is called a “particle electrode”, where electrically conductive particles are placed between an anode and cathode. Upon application of an electric current across an exhausted bed of adsorbent, two mechanisms are hypothesized to result in the restoration of adsorption capacity: (1) desorption and (2) degradation of the pollutant. This study evaluated the adsorption capacity and rate constants for 17 OMP on two different versions of this partly graphitized carbon (with and without iron content) as an alternative to conventional AC for drinking water treatment. By batch adsorption experiments, the adsorption properties of this novel carbon were investigated. Oxidation of zero-valent iron on the iron containing version of carbon resulted in yellowish water. This version was therefore considered not appropriate for general drinking water treatment, and the remaining experiments were conducted only with the version without iron. The material adsorbed a great variety of OMP, including different charges and hydrophobicity. Its graphite content probably promoted the adsorption of neutral compounds. A negatively charged layer formed by NOM accumulation on adsorbent surfaces assisted positively charged compounds adsorption. Investigation of regeneration efficiency was conducted with alternative cycles of adsorption and regeneration with high OMP concentration solutions. This material could be electrochemically regenerated. Reverse adsorption could be achieved on neutral, positively and negatively charged compounds in multiple cycles of regeneration. Electrodesorption is probably the major mechanism responsible for regeneration. Permanent and partial loss of adsorption capacity was recorded, probably due to poor NOM desorption and change in surface chemistry. Regeneration efficiency was not positively correlated with elevating applied current. Increasing cell voltage is not always beneficial to the electrochemical process. Prolonged treatment time improved the regeneration efficiency, but the marginal benefit was considered to be uneconomical. Poor NOM regeneration was responsible and more concerning for the loss of adsorption capacity. Long-chain PFAS regeneration was achieved over cycles of regeneration. Short-chain PFAS regeneration was unfavorable due to blockage of micropores.
...
A novel activated carbon-iron composite material has been developed as an adsorbent for water treatment. Due to its activated carbon (AC) content, the material could be used to remove pollutants such as organic micropollutants (OMP). Fast AC bed exhaustion makes adsorption a cost-intensive solution. Regeneration of AC is done off-site and requires transport and high energy consumption for heat treatment. Due to the iron and graphite content of the novel adsorbent, catalytic regeneration could allow for in-situ regeneration. This property would present a major advantage over common AC. Regeneration could potentially be realized by applying an electric current across an exhausted bed of this adsorbent. Such a setup is called a “particle electrode”, where electrically conductive particles are placed between an anode and cathode. Upon application of an electric current across an exhausted bed of adsorbent, two mechanisms are hypothesized to result in the restoration of adsorption capacity: (1) desorption and (2) degradation of the pollutant. This study evaluated the adsorption capacity and rate constants for 17 OMP on two different versions of this partly graphitized carbon (with and without iron content) as an alternative to conventional AC for drinking water treatment. By batch adsorption experiments, the adsorption properties of this novel carbon were investigated. Oxidation of zero-valent iron on the iron containing version of carbon resulted in yellowish water. This version was therefore considered not appropriate for general drinking water treatment, and the remaining experiments were conducted only with the version without iron. The material adsorbed a great variety of OMP, including different charges and hydrophobicity. Its graphite content probably promoted the adsorption of neutral compounds. A negatively charged layer formed by NOM accumulation on adsorbent surfaces assisted positively charged compounds adsorption. Investigation of regeneration efficiency was conducted with alternative cycles of adsorption and regeneration with high OMP concentration solutions. This material could be electrochemically regenerated. Reverse adsorption could be achieved on neutral, positively and negatively charged compounds in multiple cycles of regeneration. Electrodesorption is probably the major mechanism responsible for regeneration. Permanent and partial loss of adsorption capacity was recorded, probably due to poor NOM desorption and change in surface chemistry. Regeneration efficiency was not positively correlated with elevating applied current. Increasing cell voltage is not always beneficial to the electrochemical process. Prolonged treatment time improved the regeneration efficiency, but the marginal benefit was considered to be uneconomical. Poor NOM regeneration was responsible and more concerning for the loss of adsorption capacity. Long-chain PFAS regeneration was achieved over cycles of regeneration. Short-chain PFAS regeneration was unfavorable due to blockage of micropores.