摘要:

AbstractThis contribution presents the basic equations for heat, mass and momentum transfer in multicomponent packed bed distillation processes. In some situations, the use of strongly simplified models is justified, but when approaching more difficult and, at the same time, economically more interesting regions of operation where non‐linear effects are significant, these models are likely to fail. Consequently, a more rigorous vapour‐liquid equilibrium model should be employed since the pressure drop in the column will not be negligible in those regions. Furthermore, neither constant parameter hold‐ups nor heat and mass transfer coefficients are assumed. Simulations demonstrate some interesting process properties. The impact of the surroundings on the process is discussed and a three‐dimensional model extension is o

ISSN:0930-7516    

DOI:10.1002/ceat.270150102

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractMacroscopic flow properties of packed beds are strongly dependent on the structure of the pore space. In the case of permeability, the classical approach in which this coefficient is related to the mean voidage cannot be systematically applied as a predictive methodology, because the mean voidage index does not account for the morphology and topology of the porous media. In this work, a modelling technique is developed which enables the effective permeability of a binary packing of spheres to be evaluated from a detailed structural and phenomenological description of the system. The results are then compared with experimental data to confirm the predictive capability of the model.

ISSN:0930-7516    

DOI:10.1002/ceat.270150103

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn the process industries, safety problems may arise when combustible gases are transported through pipes. Therefore, it is necessary to prevent propagation of flame fronts into or through systems, in order to avoid undesired explosions and flashbacks into the production plant. Safety devices which are used in such cases are the flame arresters, e.g. water trap flame arresters. There is a maximum gas flow rate through a water trap flame arrester below which a flashback is unlikely to occur. Based on investigations of the explosion behaviour of bubbles in suspensions of glass spheres, experiments were carried out in a water trap flame arrester of industrial demensions. It is shown that the safe gas volumetric flow rate through a water trap flame arrester can be increased by up to 30% for H2/air mixtures when glass spheres are added to the liquid in the flame arrester.

ISSN:0930-7516    

DOI:10.1002/ceat.270150104

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA fluidized bed of cation exchange resin was used for the removal of cupric ions from a simulated wastewater effluent consisting of copper sulphate solution. Variables investigated were: superficial liquid velocity, particle diameter, bed height and copper sulphate concentration. These variables were studied with respect to their effect on the solid‐liquid mass transfer coefficient. The coefficient was found to increase with increasing superficial liquid velocity. Increasing particle diameter, bed height and copper sulphate concentration were found to reduce the mass transfer coefficient. The experimental data can be correlated by the equationvalid for the following conditions: 0.23

ISSN:0930-7516    

DOI:10.1002/ceat.270150105

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractUnknown reaction rates make concentration control in laboratory recycle reactors a difficult task, particularly when gas chromatographs or other analytical equipment with long analysis times from part of the control system. For such time‐delay systems, a model‐based feedforward control technique is developed which uses some kind of learning linear mapping to provide estimates of the reaction rates. Regarding the number of time steps necessary to satisfy a new set point, in a variety of simulation studies, this technique has proven superior to similar but simpler control strateg

ISSN:0930-7516    

DOI:10.1002/ceat.270150106

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractRunaway behaviour of exothermic reactions in a batch reactor has been studied experimentally on the example of acetic anhydride hydrolysis catalyzed by sulphuric acid, in a 700 ml batch reactor. High parametric senstivities of peak reactor temperature with respect to initial reactor temperature and catalyst concentration were obtained.

ISSN:0930-7516    

DOI:10.1002/ceat.270150107

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractRunaway behaviour of an exothermic reaction in a semibatch reactor was studied experimentally on the example of hydrolysis of acetic anhydride catalyzed by sulphuric acid, in a 700 cm3thinwalled stainless steel stirred reactor, 10.2 cm in diameter and 13.0 cm high. The reactor was partially immersed, to a depth of 2.1 cm, in a thermostatic bath, in order to obtain sufficiently rapid cooling of its contents. A reaction run was performed by first introducing water, acetic acid and sulphuric acid into the reactor. After the contents attained bath temperature, acetic anhydride at room temperature was fed to the reactor for a fixed time period, at a constant flow rate. When water was present in excess of the stoichiometric requirement and addition of acetic anhydride completed before the reactor attained peak temperature, the system showed sensitivity to coolant temperature and sulphuric acid concentration. When the reactants were present in stoichiometric quantities and addition of acetic anhydride was completed after the reactor attained peak temperature, the system did not exhibit any significant parametric sensitivity.

ISSN:0930-7516    

DOI:10.1002/ceat.270150108

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA one‐parameter stochastic model has been developed for the prediction of dynamic pressure drop in a deep‐bed filter. The model is based on a finite‐state and discrete‐time Markov chain method whereby the pressure drop in a deep‐bed filter can be estimated at discrete time intervals. The proposed model is simpler than the stochastic birth and death models available in literature. The bed is assumed to pass through different states of porosity during the filtration and it is spatially lumped in each state. For pressure drop calculation, the Carman‐Kozeny equation is used in conjunction with the Payatakes‐Tien‐Turian model. Model equations are simple and can be easily solved on a personal computer. The theoretical results agree well with the plant data as well as with the available ex

ISSN:0930-7516    

DOI:10.1002/ceat.270150109

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractAn experimental and analytical study of adiabatic countercurrent flow limitation (flooding) in single vertical ducts is reported. The experiments were carried out in a rectangular channel using saturated liquid and vapour of Refrigerant 12 (CCl2F2). The steady‐state liquid delivery (flooding) curves as well as local pressure drop and void fraction distributions in the countercurrent flow were measured in a range of system pressures fromp/pcrit= 0.16 top/pcrit= 0.31, and for various total liquid injection rates and locations. The measured flooding curvesj1=f(jg) as well as pressure drop and void fraction during partial liquid delivery (j1

ISSN:0930-7516    

DOI:10.1002/ceat.270150110

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractAn algorithm is presented for computing the diameter and length of RDC columns, based on the analysis of literature data and the results of author's own investigations.

ISSN:0930-7516    

DOI:10.1002/ceat.270150111

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY