ISSN:0009-286X    

DOI:10.1002/cite.330650202

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractMinimum Reflux Calculation for Nonideal Distillations. The minimum reflux ratio is the lower limit of operation for a distillative separation. Due to rising energy costs one is increasingly forced to approach this thermodynamically defined minimum energy consumption. This paper presents an overview of the important methods of calculation published to date. First, a concise physical and mathematical description of the problem is given to introduce the concept of pinch points. These are characteristic regions in separation profiles of distillation columns where an infinite number of stages would be required under minimum reflux conditions. Then, shortcut and rigorous problem solutions for both ideal and non‐ideal mixtures are reported. Ideal mixtures can be computed using the well‐known Underwood equations, which also cover complex column designs (multiple feeds/products, sidestream strippers and enrichers). However, pronouncedly non‐ideal systems still require time‐consuming simulations of columns with a large number of stages. Hence, recent developments attempt to avoid column simulations and to compute pinch points d

ISSN:0009-286X    

DOI:10.1002/cite.330650203

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330650204

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractEvaluations of Packings and the Limitations of their further Development. The performance of a newly developed packing can generally only be determined experimentally. Tests can be carried out to find the dependence on geometry, load and physical properties of the system, a knowledge of which is required to develop a physical model. Such a model then enables description of the fluid dynamic behaviour and the effectiveness of mass transfer within packed columns and their dimensioning. The model also clearly indicates the possibilities and limitations of further development of packings. Practical examples will confirm the theoretical considerations.

ISSN:0009-286X    

DOI:10.1002/cite.330650205

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractInfluence of Product Properties on Drying. A number of items of information are required for selection and design of a drying process. Thermodynamic equilibrium as well as heat and mass transfer are the traditional prerequisites for describing the drying operation. In the development of a drying process further specific properties of the product must be known. These properties, such as chemical reactions or sticking properties, greatly reduce the number of possible drying processes. For this reason, the measurement of these properties plays an important role in the development of a drying process. Many of the bench scale tests in use do not have a physical basis, but have been developed empirically because the physical context is often unknown. Yet a number of physically well‐defined methods are available for product characterization. In practical work a combination of empirical and scientifically defined methods is use

ISSN:0009-286X    

DOI:10.1002/cite.330650206

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractDesign of Contact Dryers for Free Flowing Solids Loaded with Solvent Mixtures. Vacuum contact drying of free flowing granular material loaded with a binary volatile mixture (iso‐propanol/water) has been studied experimentally in a bench scale disc dryer of 250 mm diameter. Particle diameters ranged from 1 to 5 mm, the pressure was 1250 Pa and the wall temperature was between 50°C and 180°C. Both the drying rate as well as the selectivity of the drying process could be predicted well by the previously developed so‐called heat transfer penetration model together with vapor phase mass transfer correla

ISSN:0009-286X    

DOI:10.1002/cite.330650207

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractGrowth of Deposits on Pipes in a Field of Flow. The deposition of ash particles on the heat pipes of steam generators represents an energy and safety problem. A deterministic single‐particle model was used to simulate this deposit formation. The numeric solution of the equation of motion gives the distribution of the impact points of the particles on the pipe surface. A particle mass balance allows calculation of the deposit formation δ (φ, t) on a pipe in space and time. Even if only a simple adhesion model is used, the calculated shape of the deposit can approach real deposit shapes. The effect of the sticking probability on deposit shape and formation time is shown. Numeric and analytical studies indicate the existence of stable limiting forms of the deposit. Thus, pipe forms can be calculated which allow only low levels of deposition and erosion. The model can be applied to particle‐fluid flows around other con

ISSN:0009-286X    

DOI:10.1002/cite.330650208

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330650209

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330650210

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330650211

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY