摘要:

A new method for hold-up measurement is described. Holdup in the column is calculated from the data on the phase ratio in the samples of the dispersion drawn-off from the column through a capillary at different sample flowrates. Local holdup and drop size distribution have been measured in a 50 mm ID vibrating plate column. It has been found that the drop size distributions at different agitation intensities are similar and that the dependence of the number density on the dimensionless drop volume can be described by the Gamma distribution.

ISSN:0098-6445    

DOI:10.1080/00986448608911686

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Most of the models found in the literature for predicting diffusion coefficients in liquids take the viscosity of the solution as inversely proportional to the diffusivity. A model (previously derived for sucrose-water system)which considers the viscosity raised to the two-third power, is evaluated here using published data for the Benzene—Cylohexane, Ethanol-Water and Acetone-Chloroform systems. These results, and results for the sucrose-water system are compared with the experimental values, and with those obtained using the Hartley—Crank equation. Better agreement with the experimental values at low and in the middle of the concentration range was found when diffusivities were calculated using the model proposed than when using the Hartley-Crank equation.

ISSN:0098-6445    

DOI:10.1080/00986448608911687

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The problem of the optimal distribution of two multifunctional catalysts is analyzed. Two methods for obtaining optimal catalyst profiles, an analytic-numeric method and the method of steepest ascent, are compared. Though the analytic-numeric method yields a more accurate solution, the method of steepest ascent is usually easier to apply. Optimal catalyst loading profiles are determined for two cases of commercial interest: selective oxidation of butene and naphtha reforming with bimetallic catalysts- A sequential loading of the bismuth molybdate and the vanadium phosphate catalysis is recommended for low butene concentration levels, while at higher butene levels a mixed loading of the two catalysts may be desirable. For commonly encountered naphtha feedstocks a sequential loading of the Pt-Re and the Pt-Ir catalysts tends to be optimal. These compare well with experimental evidence in the literature.

ISSN:0098-6445    

DOI:10.1080/00986448608911688

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

It is shown by use of examples (a C.S.T.R. and a recycle plug flow reactor)that the asymptotic behaviour of Zwietering's maximum-mixed reactor model is the source of multiple solutions. It is further demonstrated that Zwietering's so-called “boundary conditions”, when they are valid, are actually a description of the asymptotic behaviour of the system equations.

ISSN:0098-6445    

DOI:10.1080/00986448608911689

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hydrodynamics and gas/fiquid mass transfer in fluidized beds of glass spheres (3–8 mm diameter)were studied employing viscous aqueous solutions (16–53 mPas) Increasing liquid viscosity reduced the bubble disintegration capability of the particle beds. The most pronounced consequence was a strong decrease in the volumetric mass transfer coefficients (kLa) From a comparison of kLa in Newtonian and pseudoplastic liquids it is concluded that the effective shear rates in three-phase fluidized beds are higher than in bubble columns.

ISSN:0098-6445    

DOI:10.1080/00986448608911690

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Gas hold-up and mass transfer were examined in a column with and without a draft tube. It was found that the introduction of a draft tube increases the gas hold-up but decreases the volumetric mass transfer coefficient in Newtonian fluid systems. For non-Newtonian fluid systems, both parameters were increased by the presence of the draft tube. Empirical correlations are proposed for the gas hold-up and the volumetric mass transfer coefficient in the bubble column with Newtonian and non-Newtonian fluid systems. The correlations are in general agreement with the data in this work and in the literature. They should be useful for design and scale-up purposes. It was also found that introduction of an ancillary impeller improves the mass transfer in non-Newtonian fluids due to the break-up of large bubbles.

ISSN:0098-6445    

DOI:10.1080/00986448608911691

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The dielectric constant and the ionic conductivity are measured for a slurry flowing in a conducting pipe. These properties are determined from a measurement of the wavelength, frequency and attenuation of radio waves propagating inside the pipe. A mixing model is used to infer the solids fraction of the slurry.

ISSN:0098-6445    

DOI:10.1080/00986448608911692

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Three-phase slurry bubble column reactors are used in a wide variety of biological and chemical operations. This work is a comprehensive review of the mathematical modeling of such reactors for the Fischer-Tropsch (F-T)synthesis as applied to indirect coal liquefaction. The salient features of the F-T slurry bubble column reactors are described, and the fundamental mass transfer and kinetic rate processes that are needed to model the reactor performance are discussed. A brief description of the F-T chemistry, including principal F-T reactions, properties of commonly used F-T catalysts, and the Schulz-Flory distribution, is also given. All of the mathematical models for the F-T slurry process that have been developed to date are presented in enough detail to highlight the basic relations as well as the implicit assumptions. The refinements introduced by different workers are emphasized, as well as the numerical results obtained from these models either in the perspective of comparison with experimental data or in relation to design implications. The controversy surrounding the importance of relative mass transfer resistance in F-T slurry reactors is discussed. It is concluded that none of the available models includes enough details in relation to hydrodynamics, kinetics, and F-T chemistry to provide a reliable base for either prediction of conversion or optimum reactor design. Suggestions are given to develop such a comprehensive model, and the particular features that must be included in its formulation are elaborated.

ISSN:0098-6445    

DOI:10.1080/00986448608911693

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Incineration in a properly designed and operated facility has been recommended as a preferred control technology for combustible organic hazardous wastes. In principle, a completely efficient incinerator converts organic hazardous material via high temperature thermal oxidation to carbon dioxide, water and low volume inert ash material. During the incineration of halogenated hazardous waste streams, significant quantities of halogen acids are also formed. In order to optimally design incinerators and to ensure that incinerators perform according to current United States Environmental Protection Agency regulations, it is critical to better understand the thermal destruction behavior of organic hazardous wastes.

ISSN:0098-6445    

DOI:10.1080/00986448608911694

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Adsorption of acetylene, vinyl chloride and hydrogen chloride on activated carbon has been investigated using a transient response technique over a temperature range of 25–200°C. Thermodynamics and adsorption parameters have been estimated from the well-known correlations and gas-phase concentration profiles. Physical adsorption and chemisorption have been found distinguishable.

ISSN:0098-6445    

DOI:10.1080/00986448608911695

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor