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Hydrodynamic Studies Of The Flow Of Fine Particles Through A Fluidized Dense Bed Of Coarse Solids, Jaideep Talukdar

Doctoral Dissertations

This study explains the hydrodynamics of a circulating fluidized bed (CFB) system, the Battelle Multi-Solids Fluidized Bed System (MSFB). It consists of a circulating fluidized bed of fine particles superimposed on a bubbling bed of coarse solids.

One way to characterize such a system is to describe the mechanism of gas-solid flow through the bed. The gas flow in systems like these is through bubbles or slugs (regions of voids containing little or no solids). Bubbles are typically characterized by their size (length or diameter), their rise velocity, and their frequency.

Another task of the initial phase of this study …

Rapid Hydropyrolysis Of Coals For Production Of Liquid Hydrocarbons, Abdul Rahman Mohamed

Doctoral Dissertations

Production of fuels and chemicals from coal is becoming attractive due to potential high cost and uncertain supply of crude petroleum oil. Conventional techniques of coal liquefaction, though technically feasible, have been expensive due to hydrogen requirements, high pressure equipment, and high cost of commercial supported catalysts.

In this study, a novel technique for rapid hydropyrolysis of bituminous, subbituminous, and lignite coals has been investigated. Rapid hydropyrolysis is the process of heating at a fast rate to high temperature in a hydrogen environment. A coal sample in hydrogen atmosphere is targeted, in the absence of a catalyst, with a high …

Hydrodynamics And Heat Transfer Of Circulating Fluidized Bed, Chunming Qi

Doctoral Dissertations

The investigation of the hydrodynamics of gas-particle suspension in a circulating fluidized bed (CFB) focused on the radial (lateral) particle flux measurement, the mechanism of the radial particle concentration distribution, the mechanism and the model of particle convection heat transfer, and the pressure balance in the CFB loop, all of which affect the hydrodynamics, thermal efficiency and stability of a CFB.

The radial particle fluxes in a cold-flow CFB riser (14.0 cm i.d., 6.4 m high) were directly measured by specially designed probes. Two types of particles were used; glass beads of 200 $\mu$m diameter, and FCC catalyst of 70 …

Potential Use Of Ultrasound In Chemical Monitoring, Grazyna Elzbieta Orzechowska

UNLV Retrospective Theses & Dissertations

The objective of this study was to examine the potential of combining sonication with other technologies for monitoring specific classes of organic pollutants in water. The research specifically addressed using ultrasonic processors to decompose organochlorine compounds into ions which could be detected using a specific ion electrode as a screening method for organochlorine pollutants. Changes in chloride, conductivity, and pH were measured using commercially available equipment before and after sonication in order to detect the presence of the organochlorine pollutant. Chloride ion could be detected in aqueous solutions of low ppm concentrations of carbon tetrachloride, chloroform, and trichloroethylene after one …

An Algorithm For Supervisory Multivariable Constrained Optimization Of Industrial Processes., William E. Daniel Jr

LSU Historical Dissertations and Theses

An algorithm is presented for supervisory optimization of industrial processes that combines the minimization of operating costs with process operating constraints. The supervisory algorithm manipulates the set points of a lower-level control system and the set points are updated at long enough intervals of time so that the process reaches steady state between set point updates. This steady state assumption greatly simplifies the algorithm computations and, more importantly, significantly reduces the effort required for process identification. This dissertation develops the algorithm and then presents results from its application to a simulated distillation train and reactor feed network. In both applications, …

Mathematical Model Of Hairy Root Growth., Seungdo Kim

LSU Historical Dissertations and Theses

Hairy roots produce secondary metabolites which have been used as specialty chemicals. The mathematical models of hairy root growth kinetics can guide the design and scale-up of root cultures. An unstructured segregated and a chemically structured segregated models for hairy growth kinetics are formulated with rules of root branching processes. The deterministic branching rule and the stochastic branching rule are studied. For the deterministic rule where two branching parameters are assumed constant, the number of tips can be obtained by solving a linear difference equation. The conceptual framework established for the deterministic rule is used to formulate a stochastic rule …

Kinetics Of Growth And Ice Nucleation Activity Of Pseudomonas Syringae, Amarjeet Singh Bassi

Digitized Theses

Pseudomonas syringae causes freezing of supercooled water at temperatures close to 0{dollar}\sp\circ{dollar}C. In this study, the growth kinetics and ice nucleation activity (INA) of the bacterium P. syringae cit 7 were investigated under a variety of culture conditions as well as in batch and continuous bioreactors. The "drop freezing assay" technique used for measurement of INA was first investigated and the effect of several variables on this assay was examined. When P. syringae cit 7 was cultured aerobically in a medium consisting of sucrose, peptone, K{dollar}\sb2{dollar}HPO{dollar}\sb4{dollar}, KH{dollar}\sb2{dollar}PO{dollar}\sb4{dollar}, and MgSO{dollar}\sb4\cdot{dollar}7H{dollar}\sb2{dollar}O (pH 7.0) at 25{dollar}\sp\circ{dollar}C for 48 h, the highest INA was …

Catalytic Cracking Of Hydrocarbons With Novel Metal Traps, Hany Iskandar Farag

Digitized Theses

Nickel and vanadium poison FCC catalysts with destruction of zeolites. This is reflected by a lower gas oil conversion and lower gasoline selectivity. Ni and V also affect hydrogen transfer resulting in more coke formation and reducing light gases.;New catalysts, so-called FCCT (catalysts for FCC with "in situ metal traps"), were developed in this study to achieve high dispersion of passivators. FCCTs were extensively tested and demonstrated experimentally. On the strength of these results, it can be stated that high dispersion of the metal traps, using the "in situ" mode of preparation with traps "waiting" the contaminants and "shielding" the …

Fluid Dynamics Of High-Temperature Bubble And Slurry Bubble Columns, Julie Chabot

Digitized Theses

The present Ph.D. dissertation was focused on the study of the fluid dynamics of high temperature bubble and slurry bubble columns. The study was centred on a system of particular interest for the petrochemical industry, the liquid phase methanol synthesis process, for which very little information is currently available. Emphasis was placed on the study of important gas phase parameters, including the gas holdup, the bubble rise velocity, the bubble chord length and the bubble chord length distribution, which were measured using spherical bulb fibre optic sensors.;The experiments were conducted in a 0.2 m diameter and 2.4 m height carbon …

Modern And Decentralized Control For Multivariable Processes, Zhong-Xiang Zhu

Digitized Theses

Control methodologies to cope with multivariable process systems are studied in this thesis. Topics on both modern and conventional decentralized control strategies are covered with the major focus on the latter.;In the modern control aspect, the two most common approaches--the LQ optimal control and the eigenvalue assignment design are discussed. Emphasis is placed on investigation of LQG applications to complex real-time processes, and eigenvalue assignment design for improved steady state and robust performance. By careful consideration of practical issues and innovative use of model identification techniques, a strongly interactive and non-linear multivariable pressure tank system is satisfactorily controlled by the …

Effects Of Environmental Factors On Anaerobic Granular Sludge In Upflow Anaerobic Sludge Blanket Reactors, Chun Fang Shen

Digitized Theses

Effects of environmental factors (micronutrients and toxicants) on high rate anaerobic digestion and anaerobic granular sludge were studied in laboratory-scale (20 litres) and bench-scale (1.2 litres) upflow anaerobic sludge blanket (UASB) reactors.;The anaerobic bacteria, when grown in feed lacking iron and cobalt, could become iron and/or cobalt deficient and had low specific activity. Supplements of iron and cobalt in the feed provided sufficient amount of these elements for the bacterial metabolism, and excellent COD digestion rates could be maintained in the reactors. Yeast extract showed a strong positive effect on the bacterial growth rate, but had no significant contribution to …

A Characterization Of The Fast Pyrolysis Of Cellulose And Wood Biomass, Robert George Graham

Digitized Theses

The science of biomass fast pyrolysis is relatively young and incomplete. To date, there has been no systematic attempt to define fast pyrolysis in terms of chemistry, product distribution, kinetics, heat transfer requirements, and requisite process conditions. Neither has there been any experimental work which tracks the reaction progress as a function of both temperature and residence time. Furthermore, the literature provides a fragmented and often contradictory view of the nature of fast pyrolysis.;This thesis provides a coherent picture of the fast pyrolysis of cellulose and wood via an extensive literature review and systematic research. The literature review is an …