ISSN:0009-286X    

DOI:10.1002/cite.330610502

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractModern electrolysis processes for the hydrogen technology.This survey discusses all processes of water electrolysis after having emphasized the central role, which hydrogen plays in chemical technology and which it might play in a hydrogen economy, with the aid of some historical considerations and applications in hydrogen energy systems. In order to understand the development potential of the processes, the physico‐chemical fundamentals as well as the problems of the engineering of water electrolysis are summarized in a structural form. Not only are the purely electrochemical processes reviewed by a classifying systematic, but also all other (indirect) processes, which include an electrochemical step. The following direct processes are discribed: conventional and advanced alkaline water electrolysis, medium temperature cells, acid water electrolysis, membrane water electrolysis, water vapor electrolysis with proton conductive solid electrolyte and high temperature water electrolysis as well as the indirect processes: electrochemical raw material gasification, thermochemical‐electrochemical hybrid processes, photochemical‐electrochemical hybrid processes, and the photoelectrochemical cleavage of

ISSN:0009-286X    

DOI:10.1002/cite.330610503

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractWave propagation phenomena in chemical engineering processes.A phenomenological analysis of the dynamics of a number of different distributed parameter systems in chemical engineering reveals a surprisingly simple dynamic behaviour despite the complexity of the underlying nonlinear process models. Spatial structures or waves are propagating along a spatial coordinate during transients. The dynamics of most of the processes under consideration can be described with sufficient accuracy by three different model structures. These models serve as a basis for a theoretical system analysis. The investigation of characteristic properties of the propagating waves and the mechanisms responsible for wave formation are of central significance. Finally, it is shown how the extended knowledge about the processes may be applied for the solution of problems of technical interest.

ISSN:0009-286X    

DOI:10.1002/cite.330610504

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractEnvironmental protection ‐‐ a permanent challenge.Through the intensive investment activity of municipalities and of the chemical and related industries in the past twenty years it has been possible to greatly reduce the extent of environmental pollution which rose as a result of the rapid urban expansion and industrialisation of the 1950's and 60's. However, a more thorough protection of river and sea waters cannot be achieved merely through the further sophistication of waste‐water technologies. More importantly, every possibility for reducing the quantity and pollutant content of waste‐water must be fully exploited. Such possibilities lie in the recycling of processing water, in the integration of environmental protection into the process itself, as well as in the appropriate redesign and modification of the processes. The various fields of activity, especially those particularly rewarding to the process engineer are examined and numerous possible directions are offered. Six technical examples, which have been applied in practice, serve as illus

ISSN:0009-286X    

DOI:10.1002/cite.330610505

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractInfluence of additives and contaminants on crystallisation processes.The presence of additives and contaminants in a crystallising solution can have a considerable influence on the crystallisation properties of the products, such as nucleation and growth kinetics, agglomeration or dispersion of the crystals, and the incorporation of foreign ions into the crystal lattice. These influences are caused by various mechanisms, depending upon the type of additive or contaminant. Tailor‐made and multifunctional additives are distinguished. Trace amounts of metal ions can also modify the kinetics of crystallisation. The metal ions can be incorporated to a greater or lesser extent in the crystal, depending upon thermodynamic and kinetic factor

ISSN:0009-286X    

DOI:10.1002/cite.330610506

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPhysicochemical separation processes in biotechnology.A number of special features of the work‐up of products of biotechnological processes play a decisive role in selection of a separation process. Thus the products generally have to be isolated from dilute aqueous solutions. Moreover, the substances to be isolated are generally sensitive to external influences such as temperature or pH value and have to be isolated from mixtures with chemically similar compounds. Demands for greater selectivity of separation are met by processes based on differences in molecular structure of the substances to be separated. These include separation methods which have practically no significance in chemical engineering, e. g. chromatographic, membrane, and electrophoretic processes. The development of industrially utilizable processes to exploit the high separation efficiency of the physicochemical techniques requires close collaboration between process engineers and chemist

ISSN:0009-286X    

DOI:10.1002/cite.330610507

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330610508

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330610509

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330610510

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330610511

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY