Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor Mbr Using Developed Experimental Methods And Cfd Simulation
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Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor Mbr Using Developed Experimental Methods And Cfd Simulation
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Author : Vineet Alexander
language : en
Publisher:
Release Date : 2018
Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor Mbr Using Developed Experimental Methods And Cfd Simulation written by Vineet Alexander and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
"Upflow Moving Bed Hydrotreater (MBR) reactor is used for hydrotreating resid crude oil. It is a two-phase upflow reactor having a catalyst bed with conical bottom, and plena. At industrial conditions the reactor is not performing at its best and encountering issues such as hot spots, catalyst agglomeration inside the catalyst bed leading to frequent shutdown of the reactor. The root cause of these problems are linked to the improper hydrodynamics inside the catalyst bed. To investigate this, the industrial scale MBR is scaled down to a pilot scale and indicative and key hydrodynamic parameters are investigated using developed experimental methods and CFD simulation. The local hydrodynamics is quantified using an experimental technique called two-tip optical probe (TTOP). Developed algorithms for TTOP to derive the local phase saturations, velocities, backmixing, maldistribution using the time series data of the probe. The results indicates high maldistribution zones inside the catalyst bed and found convincing evidence to link this to the conical design and plena of MBR. Overall Gas and Liquid dispersion/Mixing in the catalyst bed is investigated by tracer studies using a developed methodology based on residence time distribution (RTD), Convolution, Regression, and Catalyst Bed Models based on axial dispersion and wave model. Good gas/liquid dispersion is seen at the industrial scaled down operating condition. A CFD model is developed for the lower plenum of MBR and validated with gamma ray densitometry (GRD) for radial profile of line average phase volume fraction. The simulation indicates that the current design of lower plenum is enabling a dominant movement of phases only in the central region outlets of this plenum. A modification of the current design proves to perform better in terms of movement of phases along entire outlets of the lower plenum"--Abstract, page iv.
Hydrodynamics Of Trickle Bed Reactors
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Author : Zeljko Kuzeljevic
language : en
Publisher:
Release Date : 2010
Hydrodynamics Of Trickle Bed Reactors written by Zeljko Kuzeljevic and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Electronic dissertations categories.
In this study we develop the computational and experimental tools to assist us in performance evaluation of trickle bed reactors (TBRs). The study focuses on experimental characterization of the flow distribution, and development of computational fluid dynamics (CFD) model of trickle flow. The experimental study has been performed to examine the quality of liquid phase distribution in a high pressure system. The results were provided in terms of distribution of the effluent liquid fluxes and cross-sectional liquid holdups. Their individual trends, but also their relation with respect to operating conditions was examined. Characterization of bed porosity distribution has been performed and used as the input to the computational model. The experimental study of the dependence of the extent of hysteresis on operating parameters in a high pressure TBR was performed. The extent of hysteresis was found uniquely determined by the pressure drop in the Levec prewetting mode. This fact and developed CFD model were then used to deduce conditions leading to operation with negligible hysteresis effects. Three-dimensional Eulerian CFD model is developed. Phase interaction closures are based on the film flow model, principles of statistical hydrodynamics and relative permeability concept. Model has been assessed against experimental data for liquid holdup, wetting efficiency and pressure drop hysteresis. Hydrodynamic Eulerian CFD model is then used together with species balance to examine the TBR performance for gas and liquid reactant limited systems. For each case a closed form approach of coupling bed and particle scale solution within CFD framework was presented.
Performance Of Multiphase Packed Bed Reactors And Scrubbers On Offshore Floating Platforms Hydrodynamics Chemical Reaction Cfd Modeling And Simulation
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Author : Amir Motamed Dashliborun
language : en
Publisher:
Release Date : 2018
Performance Of Multiphase Packed Bed Reactors And Scrubbers On Offshore Floating Platforms Hydrodynamics Chemical Reaction Cfd Modeling And Simulation written by Amir Motamed Dashliborun and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Floating production storage and offloading (FPSO) systems have been introduced to offshore hydrocarbon exploitation sectors as readily movable tools for development of small or remote oil and gas fields in deeper water. These systems are increasingly contemplated for onboard treatment and refining operations of hydrocarbons extracted from undersea reservoirs near extraction sites using embarked packed-bed scrubbers and reactors. Numerous efforts in the literature to uncover the hydrodynamics of multiphase flow in packed beds have disclosed that such reactors continue to challenge us either in their design/scale-up or their operation. Furthermore, when such reactors are subjected to marine conditions, the interaction of phases becomes even more complex, resulting in further challenges for design and scale-up. The proposed research aims at providing important insights into the performance of two-phase flow packed-bed reactors in the context of floating industrial applications. To achieve this aim, a hexapod ship motion simulator with six-degree-of-freedom motions was employed to emulate FPSO movements while capacitance wire mesh sensors (WMS) and electrical capacitance tomography (ECT) coupled with the packed bed scrutinized on-line and locally the two-phase flow dynamic features. The effect of column tilts and oscillations on the hydrodynamic behavior of multiphase packed beds was investigated and then the results were compared with their corresponding onshore analogs. Moreover, potential operational strategies were proposed to diminish fluid maldistribution resulting from bed oscillations as well as for process intensification of heterogeneous catalytic reactions in packed-bed reactors. In parallel with the experiment studies, a 3D transient Eulerian CFD model was developed to simulate the hydrodynamic behavior of multiphase packed beds under column tilts and oscillations. Ultimately, a systematic experimental study was performed to address the amine-based CO2 capture performance of packed-bed scrubbers on board offshore floating vessels/platforms. Apart from gaining a comprehensive knowledge on the influence of translational and rotational movements on multiphase flows in porous media, oil and gas sectors and ship industry would benefit from the results of this work for design and scale-up of industrial reactors and scrubbers.
On The Prediction Of Gas Hold Up In Ebullated Bed Reactors
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Author : Amir Mowla
language : en
Publisher:
Release Date : 2019
On The Prediction Of Gas Hold Up In Ebullated Bed Reactors written by Amir Mowla and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Commercial ebullated bed reactors (EBRs) are three-phase fluidized bed systems used for hydroprocessing (upgrading) of bitumen, a major Canadian resource. The objective of this thesis is to improve the understanding of the hydrodynamics of the EBRs through a combination of experimental investigation and CFD modeling. The experiments were conducted in a transparent cold-flow pilot scale reactor (inner diameter of 15.2 cm and total height of 2.2 m and were focused on the most important parameter in the design and operation of fluidized bed systems, i.e., the overall (average) gas hold-up. The pilot scale setup was operated in both two-phase (gas-liquid) and three-phase (gas-liquid-solid) modes in order to investigate the fluid dynamics in the bed and the freeboard regions present in EBRs. In two-phase flow mode, experiments were performed with and without internal gas/liquid separators (recycle cups connected to a recycle line). The recycle cups were fabricated on the basis of designs proposed in the patent literature using a desktop 3-D printer. Different concentrations of ethanol were added to distilled water in order to reproduce the conditions of high gas hold-up and foaming frequently observed in commercial EBRs. The two-phase systems were also simulated with the Euler-Euler model using a finite volume method in the OpenFOAM toolbox. The average bubble size is a key input to this model and must be representative of the physical system. Provided this condition is met, the Euler-Euler model can predict the average gas hold-up under conditions of homogeneous (dispersed) two-phase flow to within 10% of the experimental values, regardless of the mode of operation (co-current vs. bubble column). Predictions of the gas hold-up under conditions of co-current heterogeneous two-phase flow are, however, less accurate (22% average error) - a result likely linked to limitations of the available empirical swarm correction models. Experiments in the systems with recycle cups showed that the performance of the cups in gas/liquid separation deteriorated in foaming systems. Also increasing the inlet liquid flow rate and/or recycle liquid flow increased the amount of entrained gas in the recycle stream. Simulation of these experiments highlighted the strengths and limitations of the Euler-Euler model. As far as three-phase systems are concerned, a meta-analysis of a large body of published data produced a set of empirical correlations for predicting the overall gas hold-up data for systems operating with water and spherical particles. Experiments conducted to investigate the effect of particle wettability on the gas hold-up in a three-phase fluidized bed demonstrated the limitations of such an empirical approach. For the system operating with hydrophilic particles, gas hold-up values of up to 15% were predicted with less than 25% error by the most accurate correlations. For the system of hydrophobic particles, however, the correlations failed in prediction of gas hold-up and the average error was more than 56%. Experiments demonstrated that rendering the particles hydrophobic decreased the gas hold-up by more than 20%. This was found to be the result of larger bubble size distribution in the bed of hydrophobic particles. In these systems, adhesion of bubbles to particles formed bubble-particle agglomerates with less apparent density than bare particles. Such gas-padded particles have less ability to penetrate and break-up the bubbles. Consequently, the average bubble size was larger in the bed of hydrophobic particles and also in the freeboard region above the bed. According to the semi-empirical models on foam height dynamics, steady state foam thickness is inversely proportional to the bubble diameter. Therefore, foam thickness is expected to be smaller for the system of hydrophobic particles. The foam thickness measurements in this study were consistent with the findings of the semi-empirical models.
Bioreactors For Microbial Biomass And Energy Conversion
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Author : Qiang Liao
language : en
Publisher: Springer
Release Date : 2018-04-20
Bioreactors For Microbial Biomass And Energy Conversion written by Qiang Liao and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-04-20 with Technology & Engineering categories.
This book discusses recent trends and developments in the microbial conversion process, which serves as an important route for biofuel production, with particular attention to bioreactors. It combines microbial conversion with multiphase flow and mass transfer, providing an alternative perspective for the understanding of microbial biomass and energy production process as well as enhancement strategy. This book is relevant to students and researchers who work in the fields of renewable energy, engineering and biotechnology. Policymakers, economists and industry engineers also benefit from this book, as it can be used as a resource for the implementation of renewable energy technologies.
Prospects Of Renewable Bioprocessing In Future Energy Systems
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Author : Ali Asghar Rastegari
language : en
Publisher: Springer
Release Date : 2019-04-03
Prospects Of Renewable Bioprocessing In Future Energy Systems written by Ali Asghar Rastegari and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-04-03 with Technology & Engineering categories.
This book discusses various renewable energy resources and technologies. Topics covered include recent advances in photobioreactor design; microalgal biomass harvesting, drying, and processing; and technological advances and optimised production systems as prerequisites for achieving a positive energy balance. It highlights alternative resources that can be used to replace fossil fuels, such as algal biofuels, biodiesel, bioethanol, and biohydrogen. Further, it reviews microbial technologies, discusses an immobilization method, and highlights the efficiency of enzymes as a key factor in biofuel production. In closing, the book outlines future research directions to increase oil yields in microalgae, which could create new opportunities for lipid-based biofuels, and provides an outlook on the future of global biofuel production. Given its scope, the book will appeal to all researchers and engineers working in the renewable energy sector.
Bonus Algorithm For Large Scale Stochastic Nonlinear Programming Problems
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Author : Urmila Diwekar
language : en
Publisher: Springer
Release Date : 2015-03-05
Bonus Algorithm For Large Scale Stochastic Nonlinear Programming Problems written by Urmila Diwekar and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-03-05 with Business & Economics categories.
This book presents the details of the BONUS algorithm and its real world applications in areas like sensor placement in large scale drinking water networks, sensor placement in advanced power systems, water management in power systems, and capacity expansion of energy systems. A generalized method for stochastic nonlinear programming based on a sampling based approach for uncertainty analysis and statistical reweighting to obtain probability information is demonstrated in this book. Stochastic optimization problems are difficult to solve since they involve dealing with optimization and uncertainty loops. There are two fundamental approaches used to solve such problems. The first being the decomposition techniques and the second method identifies problem specific structures and transforms the problem into a deterministic nonlinear programming problem. These techniques have significant limitations on either the objective function type or the underlying distributions for the uncertain variables. Moreover, these methods assume that there are a small number of scenarios to be evaluated for calculation of the probabilistic objective function and constraints. This book begins to tackle these issues by describing a generalized method for stochastic nonlinear programming problems. This title is best suited for practitioners, researchers and students in engineering, operations research, and management science who desire a complete understanding of the BONUS algorithm and its applications to the real world.
Multiphase Catalytic Reactors
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Author : Zeynep Ilsen Önsan
language : en
Publisher: John Wiley & Sons
Release Date : 2016-06-09
Multiphase Catalytic Reactors written by Zeynep Ilsen Önsan and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-06-09 with Technology & Engineering categories.
Provides a holistic approach to multiphase catalytic reactors from their modeling and design to their applications in industrial manufacturing of chemicals Covers theoretical aspects and examples of fixed-bed, fluidized-bed, trickle-bed, slurry, monolith and microchannel reactors Includes chapters covering experimental techniques and practical guidelines for lab-scale testing of multiphase reactors Includes mathematical content focused on design equations and empirical relationships characterizing different multiphase reactor types together with an assortment of computational tools Involves detailed coverage of multiphase reactor applications such as Fischer-Tropsch synthesis, fuel processing for fuel cells, hydrotreating of oil fractions and biofuels processing
Coffee
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Author : Yi-Fang Chu
language : en
Publisher: John Wiley & Sons
Release Date : 2012-03-27
Coffee written by Yi-Fang Chu and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-03-27 with Technology & Engineering categories.
Coffee: Emerging Health Benefits and Disease Prevention presents a comprehensive overview of the recent scientific advances in the field. The book focuses on the following topics: coffee constituents; pro- and antioxidant properties of coffee constituents; bioavailability of coffee constituents; health benefits and disease prevention effects of coffee; and potential negative impacts on health. Multiple chapters describe coffee's positive impact on health and various diseases: type 2 diabetes; neurodegenerative diseases (Parkinson's and Alzheimer's); cancer (prostate, bladder, pancreatic, breast, ovarian, colon and colorectal); cardiovascular health; and liver health. Coffee's positive effects on mood, suicide rate and cognitive performance are addressed as are the negative health impacts of coffee on pregnancy, insulin sensitivity, dehydration, gastric irritation, anxiety, and withdrawal syndrome issues. Written by many of the top researchers in the world, Coffee: Emerging Health Benefits and Disease Prevention is a must-have reference for food professionals in academia, industry, and governmental and regulatory agencies whose work involves coffee.
Modeling And Simulation Of Catalytic Reactors For Petroleum Refining
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Author : Jorge Ancheyta
language : en
Publisher: John Wiley & Sons
Release Date : 2011-04-20
Modeling And Simulation Of Catalytic Reactors For Petroleum Refining written by Jorge Ancheyta and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-04-20 with Technology & Engineering categories.
Modeling and Simulation of Catalytic Reactors for Petroleum Refining deals with fundamental descriptions of the main conversion processes employed in the petroleum refining industry: catalytic hydrotreating, catalytic reforming, and fluid catalytic cracking. Common approaches for modeling of catalytic reactors for steady-state and dynamic simulations are also described and analyzed. Aspects such as thermodynamics, reaction kinetics, process variables, process scheme, and reactor design are discussed in detail from both research and commercial points of view. Results of simulation with the developed models are compared with those determined at pilot plant scale as well as commercial practice. Kinetics data used in the reactor model are either taken from the literature or obtained under controlled experiments at the laboratory.