摘要:

Mixing in a completely filled vessel, designed as a pressure vessel, has been investigated. The power demand of two pitched blade turbines of different sizes, and one high flow impeller was studied. The influence of side-mounted and bottom-mounted baffles, as well as the clearance between the bottom and the impeller was investigated. The experiments were carried out in a plexiglass vessel with a diameter of 288 mm. The Power number was calculated from measured data on the power demand and the impeller speed. Furthermore, preliminary studies on the critical impeller speed and power demand at the off-bottom suspension point for one set of glass particles were carried out. The Power number was mainly influenced by the impeller type, while the power demand at the off-bottom suspension point was more dependent of the impeller size and clearance. For bottom-mounted baffles a minimum in the Power number was noticed with increased clearance. It was found the minimum was located at the transition point between two different How patterns. This study shows that the configuration with the lowest Power number is not necessary the most efficient for suspending solid particles.

ISSN:0098-6445    

DOI:10.1080/00986449308936173

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The solid particle concentration distribution in the riser of a Circulating Fluidized Bed (CFB) is dilute at the center and dense near the wall because of the axial particle momentum exchange. In our study, the radial particle concentration distribution was investigated theoretically and experimentally. To assess the radial particle motion, a special flux probe was designed. We found that near the wall, the radial particle flux was much higher then the net axial particle flux, and that the measured radial profile of particle flux was similar to that of the particle concentration. The resulting radial flux is very valuable in developing a model of heat transfer between the gas-particle suspensions and the wall surface.

ISSN:0098-6445    

DOI:10.1080/00986449308936174

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A new kind of dimensional analysis, which uses two kinds of scales, provides a powerful tool for analyzing heat and mass transfer correlations as has been demonstrated by Ruckenstein (1986) in the case of forced convection of Newtonian fluids. In this work, the approach based on micro- and macro-scales is extended to free convection of Newtonian fluids, as well as to forced and free convection of power-law fluids.

ISSN:0098-6445    

DOI:10.1080/00986449308936175

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Process simultalion relies heavily on the calculation of physical properties through thermodynamic models. The parameters in these models are subject to uncertainties that may, at first, appear to be small. However, the designs developed through use of these models can be significantly sensitive to these parameter uncertainties. Previous studies have considered special cases of design error or have involved simple sensitivity analyses close to the optimum design case. In the present work, we use Monte Carlo simulation with Latin Hypercube Sampling to quantify the probability of design errors. An example of binary distillation with phase-equilibrium calculations from a cubic equation of state is used to illustrate the technique.

ISSN:0098-6445    

DOI:10.1080/00986449308936176

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The linear theory of Pearson (1958) and Nield (1964) is modified here to study liquid tin and include the finite thermal resistances of the bounding layers of boron nitride, copper and air (∼10−2torr) in the experiments of Gindeet al. (1989). The magnitude of the ΔTcacross the layer of liquid tin required for the onset of convection depends on the ratios of the thermal conductivities and thicknesses of the supporting layers of boron nitride and copper to those of the tin.

ISSN:0098-6445    

DOI:10.1080/00986449308936177

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

When a process model differs from the true process, the closed-loop qualities of a model-based control algorithm such as Generic Model Control are in doubt. The conditions under which stability of the closed-loop GMC system is guaranteed (“robust stability”) and the performance of the closed loop system is guaranteed to meet predetermined performance objectives (“robust performance”) are given for the first time in terms of the model and its uncertainty description. The GMC parameters which give the best performance can be determined through a simple optimisation procedure. The analytical techniques are illustrated through a simple example.

ISSN:0098-6445    

DOI:10.1080/00986449308936178

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Exothermic chemical reactions can influence natural convection effects in a porous medium. Such phenomena may occur in tubular reactors, oxidation of solid materials in large containers, chemical vapor deposition systems, liquid explosives, and others. Experimental evidence indicates that the influence of natural convection in many chemically reacting systems cannot be neglected.

ISSN:0098-6445    

DOI:10.1080/00986449308936179

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The design of equipment to sterilise solid-liquid food mixtures continuously requires that the flow properties of such mixtures be understood. Little information is available on food flows, which can consist of high solids fractions of particles of a range of densities in non-Newtonian and viscous liquids. A metal detection system which can log two types of particle in the same experiment has been constructed and used in a loop flow rig to study flows of single particles and carrot-water mixtures. Results can be correlated using the particle Froude number; some preliminary analysis is presented to suggest that data can be correlated against 1/Frp. The effect of solids fraction on particle flow velocity has been investigated; greatest variations in the particle velocity appear for stratified flows for solids fractions between 10-20%.

ISSN:0098-6445    

DOI:10.1080/00986449308936180

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An adaptive controller developed from a generalized cost function is studied in this work. Theoretical derivation is considered first. Application of such controller to a multiple-input multiple-output (MIMO) system—a binary distillation column is examined. Practical issues in the implementation of adaptive regulators to control chemical engineering processes are discussed in detail.

ISSN:0098-6445    

DOI:10.1080/00986449308936181

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A novel method, based on a single experimental test under proportional feedback, has been developed to tune PID controllers on-line. The tuning method involving an identification scheme and a dominant pole design technique is ideal for automatic tuning. It also provides an adaptive algorithm to adjust the controller settings to achieve the desirable control performance satisfying the prescribed decay ratio and stability margin. A simulation study demonstrates that the method is valid for processes with large dead-times as well as open-loop underdamped processes.

ISSN:0098-6445    

DOI:10.1080/00986449308936182

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor