14 research outputs found
Mixing and regime transition analysis of liquid-solid conical fluidized bed through RPT technique
No full textThe current work focuses on the hydrodynamic study of liquid-solid mono and binary conical fluidized bed using the radioactive particle tracking technique. Two different sizes 0.6 and 1 mm diameter glass beads were used for the experiment. Two different bed compositions, mono dispersed (100 wt% of each solid) and 50 wt% mixture of the solids, were studied. A rich data base, including instantaneous velocities, mean and RMS velocities, granular temperature, etc., were calculated by suitable post-processing. Further, Hurst exponent, autocorrelation function, segregation index, Kolmogorov entropy, and correlation dimension were calculated using time series data to understand the mixing and chaotic nature of the fluidized bed for each set of data. Good degree of mixing was observed even at a low velocity of 0.07 m/s. Kolmogorov entropy and correlation dimension indicate regime change at liquid inlet velocity of 0.1 m/s for both mono and 50 wt% binary bed.Fil: Kalo, Lipika. Indian Institute of Technology Guwahati; IndiaFil: Kamalanathan, Premkumar. Bhabha Atomic Research Centre; IndiaFil: Pant, Harish J.. Bhabha Atomic Research Centre; IndiaFil: Cassanello Fernandez, Miryam Celeste. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; ArgentinaFil: Upadhyay, Rajesh K.. Indian Institute of Technology Guwahati; Indi
Investigating chlorite dismutase biocatalyst reuse using columns
No full textMicrocontaminants are compounds in water present below 1 ppm which have major long-term health impacts. Traditional treatment processes are not designed to treat these chemicals and existing treatment methods come with downsides including higher chemical input, higher energy input, production of a waste stream, use of high cost media, and/or production of toxic byproducts. Biocatalysis, using enzymes to degrade contaminants, has been proposed as a treatment method. This process would require reuse of the biocatalysts to reduce costs for continuously operated water treatment systems. To study the potential for biocatalyst reuse, experiments were conducted on a chlorite dismutase biocatalyst modified with a strep tag; this reuse system allows the biocatalyst to bind to coated resin beads that can be reused in a column system. Chlorite dismutase treats chlorite to chloride and oxygen. Activity tests were conducted in batch for the purified and attached biocatalysts and in column to determine impact of attachment on the biocatalyst’s activity and inactivation. Activity results showed no impact of tag addition, with a tagged biocatalyst Vmax of 34,600 ± 2,900 μmol chlorite min-1 μmol heme-1 and a Km of 106.6 ± 70.6 μM. The attached biocatalyst was able to reach the same maximal activity as the free biocatalyst with the introduction of a mass transfer limited region, which can be described with a kl of 0.1415 cm min-1. Column activity was difficult to measure but was similar to the attached batch result in four successful experiments. Finally, the maximum theoretical turnover number in the column system was 152,800 ± 11,800 μmol chlorite μmol heme-1. While more understanding of the inactivation kinetics is needed to enable a detailed comparison, based on the maximum theoretical turnover number, a fully loaded column is projected to be able to treat 86,000 bed volumes (equivalent to 59.7 days at design flowrate and concentration) before being fully inactivated.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01The student, Indran Kamalanathan, accepted the attached license on 2019-10-08 at 21:50.The student, Indran Kamalanathan, submitted this Thesis for approval on 2019-10-08 at 22:04.This Thesis was approved for publication on 2019-10-09 at 15:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #14475 on 2020-02-28 at 17:35:37Made available in DSpace on 2020-03-02T22:38:38Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-10-09Embargo set by: Seth Robbins for item 113974
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No full textVirtual tracer response methodology developed based on the trajectory data of the computer aided radioactive particle tracking (CARPT) technique was demonstrated. The demonstrated virtual tracer technique has advantages of non-invasiveness, near perfect injection/sampling, and flexibility in choosing the sampling/injection boundaries in a specific spatial pattern. With the developed virtual tracer technique, liquid and solids backmixing were investigated at the conditions mimicking Fischer-Tropsch synthesis. Experiments were conducted at different pressure, solids loading, and superficial gas velocity. The axial dispersion model (ADM) and recirculation and cross flow dispersion (RCFD) models were used to model the liquid mixing. Transient sedimentation dispersion model (SDM) was used to model the solids mixing. It was found that the measured axial dispersion coefficient (Dl) in the ADM model increases with increase in the pressure. The increase of dispersion coefficient was explained with the experimental values of mean axial diffusivity and mean recirculation velocity. Axial dispersion coefficients (Dz,uDz,d) in the RCFD model (compartment model) were apparently lower than the Dl, due to the decoupling of global recirculation from the dispersion coefficients in the RCFD. Further, it was found that the dispersion coefficients in the RCFD model follow the trend of the axial eddy diffusivity with change in the operating conditions revealing the dominance of the turbulence in the upflow and downflow compartments. From the solids backmixing study, axial dispersion coefficient (Ds) of solids was found to increase with increase in the solids loading, pressure, and superficial gas velocity at the studied conditions
Gas-Liquid Mass Transfer using Advanced Optical Probe in a Mimicked FT Slurry Bubble Column
No full textGas-liquid volumetric liquid-phase mass transfer coefficient (kLα) was studied in a slurry bubble column at the conditions mimicking Fischer-Tropsch synthesis. To avoid the hydrodynamic disturbances due to the gas switching, oxygen enriched air dynamic absorption method was used. Influence of reactor models (CSTR, ADM and RCFD) on the volumetric mass transfer coefficient was investigated. Effect of operating pressure, superficial gas velocity and solids loading were investigated. From the reactor models investigated, it is recommended to use ADM model for kLα study. If the CSTR model is used, applicability of the model should be checked. With increase in the superficial gas velocity and operating pressure, volumetric liquid-phase mass transfer coefficient increases, while it decreases with the solids loading corroborating with the literature
Study of the Detailed Catalyst Hydrodynamics using Radioactive Particle Tracking Technique in a Mimicked Fischer-Tropsch Slurry Bubble Column
No full textSlurry bubble column reactor (SBCR) is the preferred choice of reactor for Fischer – Tropsch (FT) synthesis. However, the understanding of the catalyst flow dynamics in FT-SBCR is still lacking. In this work, hydrodynamics of the FT catalyst were studied using computer aided radioactive particle tracking (CARPT) technique at the mimicked conditions of FT synthesis for the first time. Solids ensemble averaged velocity, turbulent kinetic energy, Reynolds normal and shear stresses were experimentally obtained. Effect of operating conditions on the velocity flow field were investigated. Further, studies were conducted to quantify the difference in flow field due to the change in the liquid and solid phases. It was found that the change of solids turbulence is insignificant with pressure and solids loading at the studied operating conditions. Further, it was found that the surface tension of the fluid and the solid properties plays a dominant role on the turbulence
Integration of Phase Distribution from Gamma-Ray Tomography Technique with Monolith Reactor Scale Modeling
No full textIn this work, a monolith reactor model was developed to study the effect of phase distribution on the performance of the monolith reactors by integrating phase distribution data from the experiments. To obtain the phase distribution at the reactions conditions, gamma ray computed tomography (CT) was used. Effect of gas density, surface tension of liquid and operating conditions on the phase distribution were studied using gamma-ray computed tomography. Experiments were conducted in Taylor flow regime. With the increase in gas density, uniformity increases. Surface tension has little effect on the distribution in the investigated conditions. Liquid with lower surface tension and gas with lower density has higher cross-sectional liquid saturation. Further, the monolith reactor model with uniform phase distribution and actual distribution were compared. It was found that at higher velocities both gives the same reactor performance irrespective of the maldistribution, however at low velocities, they differ significantly due to the maldistribution. If the maldistribution is present at both low and high velocities, catalyst utilization plays a major role, thus it is recommended to operate at higher velocities where catalyst utilization is high due to high mass transfer
Effect of dynamic bias on accuracy of radioactive particle tracking (RPT) technique at different data acquisition frequencies
No full textEffect of Phase Maldistribution on Performance of Two-Phase Catalytic Monolith Reactor and its Comparison with Trickle Bed Reactor
No full textMonolith reactors are widely considered as an alternative to the conventional trickle bed reactor. For the commercial deployment of monolith reactors, comparative performance studies are required. Reliable comparative and performance studies require a detailed understanding of the effect of phase distribution/maldistribution on the performance studies. In this work, performance and comparative studies were carried out in a relatively large column that was 4.8 cm in diameter. Experiments were performed in the same conditions that were used in studies for which phase distribution data were available. Since the properties of the catalyst used were different in both the reactors, the apparent kinetics were studied to facilitate the comparison. The hydrogenation of alpha-methyl styrene (AMS) was used as a test reaction. From the performance studies, it was found that the effect of maldistribution on the performance was stronger than the catalyst availability. From the comparative studies, it was found that the monolith reactor with maldistributed flow conditions provides higher productivity than the trickle bed reactor
