On transverse patterns in packed-bed catalytic reactors
About: This article is published in Chemical Engineering Science.The article was published on 2001-03-01. It has received 24 citations till now. The article focuses on the topics: Packed bed & Exothermic reaction.
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TL;DR: In this paper, the authors reported the combined effect of high liquid viscosity, column diameter and operating pressure on the total gas hold-up of bubble column slurry reactors.
81 citations
TL;DR: In this paper, infrared thermography measurements in various oxidation reactions revealed high-temperature domains whose boundaries are either stationary, oscillating, moving or rotating, and these motions were observed on catalytic wires, rings, cylindrical pellets and thin catalytic beds.
56 citations
TL;DR: In this paper, the top surface of a shallow packed bed, consisting of several layers of spherical catalytic pellets (Pd/Al2O3), was used for atmospheric oxidation of carbon monoxide.
41 citations
TL;DR: In this article, an infrared camera was used to study the formation and dynamics of hot zones normal to the flow direction on the surface of a radial-flow reactor, placed horizontally, inside a vessel.
Abstract: An infrared camera was used to study the formation and dynamics of hot zones normal to the flow direction on the surface of a radial-flow reactor, placed horizontally, inside a vessel. The test reaction - the atmospheric oxidation of carbon monoxide - exhibited steady-state multiplicity. Slow cooling of the vessel caused a shift from a fully-ignited state to one with a hot zone in the center of the reactor bounded by cold zones at both reactor ends. The hot zone was separated by sharp temperature fronts from the adjacent cold zones. It shrank upon further cooling of the vessel and eventually extinguished. In certain cases, two stable states existed for the same operating conditions with qualitatively different hot zones and reaction rates. A slow back-and-forth motion of the temperature fronts (breathing) caused complex oscillations in the overall reaction rate. The dynamic features of the two fronts were different in some cases due to nonuniform catalytic activity and inefficient thermal dispersion. The amplitude and frequency of the temperature breathing motion increased upon cooling of the vessel containing the reactor. Experiments suggest that transversal hot zones are likely to form in packed-bed reactors close to the extinction temperature.
28 citations
TL;DR: In this paper, the authors investigate the interactions between the local pellet-scale dynamic responses, and the bed-scale global fields, using computational fluid dynamics (CFD) to simulate the fluid around the catalyst, coupled to transport and reaction inside it.
27 citations
References
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Book•
01 Jan 1979
TL;DR: The fundamental Mass, Energy, and Momentum Balance Equations The Batch and Semibatch Reactors The Plug Flow Reactor The perfectly mixed flow Reactor Fixed Bed Catalytic Reactors Nonideal Flow Patterns and Population Balance Models Fluidized Bed and Transport Reactors Multiphase Flow Reactors Author Index Subject Index as mentioned in this paper
Abstract: CHEMICAL ENGINEERING KINETICS Elements of Reaction Kinetics Kinetics of Heterogeneous Catalytic Reactions Transport Processes with Reactions Catalyzed by Solids Noncatalytic Gas-Solid Reactions Catalyst Deactivation Gas-Liquid Reactions ANALYSIS AND DESIGN OF CHEMICAL REACTORS The Fundamental Mass, Energy, and Momentum Balance Equations The Batch and Semibatch Reactors The Plug Flow Reactor The Perfectly Mixed Flow Reactor Fixed Bed Catalytic Reactors Nonideal Flow Patterns and Population Balance Models Fluidized Bed and Transport Reactors Multiphase Flow Reactors Author Index Subject Index.
2,746 citations
Book•
01 Jan 1985
TL;DR: In this paper, various topics in the area of combustion and explosives are discussed, including basic physical concepts of the science of combustion, the time-independent theory of thermal explosions, time-dependent statement of the problem of the initiation of chemical reaction waves in fuel mixtures, laminar flames, complex and chain reactions in flames, the gas dynamics of combustion dynamics, and diffusional combustion of gases.
Abstract: Various topics in the area of combustion and explosives are discussed. The general subjects considered include: basic physical concepts of the science of combustion, the time-independent theory of thermal explosions, time-dependent statement of the problem of the initiation of chemical reaction waves in fuel mixtures, laminar flames, complex and chain reactions in flames, the gas dynamics of combustion, and diffusional combustion of gases. 561 references.
1,585 citations
TL;DR: In this article, mass diffusivities, effective thermal conductivities, and wall heat transfer coefficients were measured in an 8-in. tube packed with 1/2-and 3/4in. glass spheres.
Abstract: Eddy mass diffusivities, effective thermal conductivities, and wall heat transfer coefficients were measured in an 8-in. tube packed with 1/2- and 3/4-in. glass spheres. Superficial mass velocities ranged from 110 to 1,640 Ib./(hr.) (sq. ft.), corresponding to modified Reynolds numbers of 100 to 2,000. Air was the main stream fluid in all cases.
The modified Peclet group (DpV/E*td) was found to be constant at a value of about 12 in the region of fully developed turbulence. At lower Reynolds numbers this group varied with the flow rate. Effective thermal conductivities were correlated by an equation. Modified Peclet numbers for heat transfer were about 25% less than those for mass transfer. The wall heat transfer coefficient varied with the superficial mass velocity as hw = 0.090 (Go0.75).
An explanation is suggested for the similarity in velocity dependence between these values and those for turbulent flow in an empty tube, based on channeling at the wall.
959 citations
TL;DR: Numerical simulations of a simple reaction-diffusion model reveal a surprising variety of irregular spatiotemporal patterns, some of which resemble the steady irregular patterns recently observed in thin gel reactor experiments.
Abstract: Numerical simulations of a simple reaction-diffusion model reveal a surprising variety of irregular spatiotemporal patterns. These patterns arise in response to finite-amplitude perturbations. Some of them resemble the steady irregular patterns recently observed in thin gel reactor experiments. Others consist of spots that grow until they reach a critical size, at which time they divide in two. If in some region the spots become overcrowded, all of the spots in that region decay into the uniform background.
862 citations
TL;DR: In this article, a series of mathematical models for a monolith catalytic converter to oxidize carbon monoxide in automobile exhaust are presented, including axial conduction in the wall, diffusion and conduction of the gas in a transverse direction perpendicular to the flow direction, multiple steady states, and transients giving wall temperatures exceeding the adiabatic temperature.
Abstract: Calculations are done for a series of mathematical models for a monolith catalytic converter to oxidize carbon monoxide in automobile exhaust. Phenomena studied include axial conduction in the wall, diffusion and conduction in the gas in a transverse direction perpendicular to the flow direction, multiple steady states, and transients giving wall temperatures exceeding the adiabatic temperature.
105 citations