Author: Amir Mowla
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
On the Prediction of Gas Hold-up in Ebullated Bed Reactors
Author: Amir Mowla
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
Prediction of Overall Gas Holdup in Bubble Column Reactors Via Neural Network Correlation
Author: Ashfaq Shaikh
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages :
Book Description
Gas-Liquid-Solid Fluidization Engineering
Author: Liang-Shih Fan
Publisher: Butterworth-Heinemann
ISBN: 1483289516
Category : Technology & Engineering
Languages : en
Pages : 784
Book Description
This book provides a comprehensive mechanistic interpretation of the transport phenomena involved in various basic modes of gas-liquid-solid fluidization. These modes include, for example, those for three-phase fluidized beds, slurry columns, turbulent contact absorbers, and three-phase fluidized beds, slurry columns, turbulent contact absorbers, and three-phase transport. It summarizes the empirical correlations useful for predicting transport properties for each mode of of operation.Gas-Liquid-Solid Fluidization Engineering provides a comprehensive account of the state-of-the-art applications of the three-phase fluidization systems that are important in both small-and large-scale operations. These applications include fermentation,biological wastewater treatment, flue gas desulfurization and particulates removal, and resid hydrotreating. This book highlights the industrial implications of these applications. In addition, it discusses information gaps and future directions forresearch in this field.
Publisher: Butterworth-Heinemann
ISBN: 1483289516
Category : Technology & Engineering
Languages : en
Pages : 784
Book Description
This book provides a comprehensive mechanistic interpretation of the transport phenomena involved in various basic modes of gas-liquid-solid fluidization. These modes include, for example, those for three-phase fluidized beds, slurry columns, turbulent contact absorbers, and three-phase fluidized beds, slurry columns, turbulent contact absorbers, and three-phase transport. It summarizes the empirical correlations useful for predicting transport properties for each mode of of operation.Gas-Liquid-Solid Fluidization Engineering provides a comprehensive account of the state-of-the-art applications of the three-phase fluidization systems that are important in both small-and large-scale operations. These applications include fermentation,biological wastewater treatment, flue gas desulfurization and particulates removal, and resid hydrotreating. This book highlights the industrial implications of these applications. In addition, it discusses information gaps and future directions forresearch in this field.
Essentials of Fluidization Technology
Author: John R. Grace
Publisher: John Wiley & Sons
ISBN: 3527699473
Category : Technology & Engineering
Languages : en
Pages : 632
Book Description
A concise and clear treatment of the fundamentals of fluidization, with a view to its applications in the process and energy industries.
Publisher: John Wiley & Sons
ISBN: 3527699473
Category : Technology & Engineering
Languages : en
Pages : 632
Book Description
A concise and clear treatment of the fundamentals of fluidization, with a view to its applications in the process and energy industries.
Modeling of Processes and Reactors for Upgrading of Heavy Petroleum
Author: Jorge Ancheyta
Publisher: CRC Press
ISBN: 1439880468
Category : Science
Languages : en
Pages : 551
Book Description
The worldwide petroleum industry is facing a dilemma: the production level of heavy petroleum is higher than that of light petroleum. Heavy crude oils possess high amounts of impurities (sulfur, nitrogen, metals, and asphaltenes), as well as a high yield of residue with consequent low production of valuable distillates (gasoline and diesel). These
Publisher: CRC Press
ISBN: 1439880468
Category : Science
Languages : en
Pages : 551
Book Description
The worldwide petroleum industry is facing a dilemma: the production level of heavy petroleum is higher than that of light petroleum. Heavy crude oils possess high amounts of impurities (sulfur, nitrogen, metals, and asphaltenes), as well as a high yield of residue with consequent low production of valuable distillates (gasoline and diesel). These
The Effect of Prewetting on the Pressure Drop, Liquid Holdup and Gas-liquid Mass Transfer in Trickle-bed Reactors
Author: Dylan Loudon
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 326
Book Description
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 326
Book Description
Gas Holdup and Liquid Phase Mixing in Trayed Bubble Column Reactors
Study of ebullated bed fluid dynamics for H-coal
Author: Amoco Oil Company. Research and Development Department
Publisher:
ISBN:
Category :
Languages : en
Pages : 68
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 68
Book Description
Gas Holdup and Liquid Recirculation in Gas-lift Reactors
Author: Yung C. Hsu
Publisher:
ISBN:
Category : Gas lift pumps
Languages : en
Pages : 472
Book Description
Publisher:
ISBN:
Category : Gas lift pumps
Languages : en
Pages : 472
Book Description
Gas Hold-up and Liquid-phase Backmixing in Bubble-column Reactors
Author: Anusorn Sangnimnuan
Publisher:
ISBN:
Category : Chemical reactors
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category : Chemical reactors
Languages : en
Pages :
Book Description