ISSN:0009-286X    

DOI:10.1002/cite.330690702

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSedimentation superimposed on industrial cake filtration leads to longer filtration times and often has a detrimental effect on subsequent process steps such as washing and demoisturing. The influence of sedimentation is seldom recognised in laboratory filtration experiments. Methods are presented for evaluation of pressure filter experiments with superimposed sedimentation which avoid the error made in the usual evaluation methods. For the case of zone sedimentation the article presents a graphical evaluation and a numerical method of modelling permitting scale up to any desired cake height. In superimposed classifying sedimentation simultaneous measurement of filtrate volume and cake height provide information about local variation in filter cake resistance. It is shown for a model system that, owing to sedimentation, the cake resistance shows a minimum at mean cake height and increases rapidly towards greater heights. The local cake resistance corelates with particle size distributions measured for layers of a horizontally cut filter cake. The method of evaluation presented permints determination of the flow resistance of the uppermost layers of a cake and hence estimation of the gas pressure necessary for demoisturing. The profiles of local filter cake resistance show that the relative cake layering is largely independent of the level of suspension filling. A scale‐up model is presented for use in those cases where classifying sedimentation cannot be suppresse

ISSN:0009-286X    

DOI:10.1002/cite.330690703

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA waste‐gas cleaning system was constructed for a group of drug production plants. The chemical – synthetic processes taking place there are characterized by inevitable emissions, mainly of vapours of organic solvents. Their concentrations vary within a wide range and at any given moment in principle remain unknown. This paper describes the initial situation and the requirements for the waste gas cleaning process, including the calculation of the gas volume flow capacity. The polluting substances were divided into two groups; for critical substances only thermal oxidation was found to be adequate, whereas for non‐critical, water‐soluble material, water‐fed absorption columns were chosen; on one hand to avoid full exhaustion of the capacity of the thermal waste‐gas system and on the other hand to offer additional possibilities in the case that this system should be out of action. The criteria for this decision as well as for the combination of one central with several decentralised cleaning units are discussed in detail. The equipment of the waste‐gas emitting plants for feeding the cleaning units and the technical details thereof are described as well as the safety design. At last, experience gaine during preparation of the systems and considerations concerning further use of the thermal cleaning system

ISSN:0009-286X    

DOI:10.1002/cite.330690704

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis article provides a brief survey of mathematical modelling of metalorganic vapour phase epitaxy (MOVPE), a step in semiconductor processing of III‐V compound semiconductors serving as basis for the production of electronic and optoelectronic components. The process model for MOVPE is based on the mathematical description of gas flow for a MOVPE reactor coupled with heat transfer and mass transport, including multicomponent diffusion, thermal diffusion, and homogeneous and heterogeneous chemical reactions. Several approaches to the description of multicomponent mass transport, of the modelling of heat transfer in terms of thermal radiation, and of the actual growth process on the growing semiconductor surface are considered. The process modell is applied to MOVPE of GaAs in an industrial multilayer reactor and the calculated results validated with the aid of experimental result

ISSN:0009-286X    

DOI:10.1002/cite.330690705

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690706

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690707

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690708

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690709

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690710

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0009-286X    

DOI:10.1002/cite.330690711

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY