ISSN:0098-6445    

DOI:10.1080/00986448308940580

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0098-6445    

DOI:10.1080/00986448308940581

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A dynamic model for continuous distillation of a binary-mixture in a stagewise column is developed to predict the transient responses to step changes in reflux ratio, boil-up rate, feed flow rate, feed temperature and composition. The nonlinear model utilizes generalized empirical relations to represent system data and avoids the assumption of constant internal flow rates. The solutions are calculated numerically. The comparisons are made with the data obtained with a twenty plate, 10 cm. diameter distillation column

ISSN:0098-6445    

DOI:10.1080/00986448308940582

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A reliable method to continuously monitor NH3in a gas stream containing CO—NO—O2and H2O has been developed. The method is based on a quantitative oxidation of NH3to NO on a Pt catalyst. The extent of this reaction is affected by temperature, excess oxygen present, and space-velocity. There is a significant effect of inlet O2concentration on extent of various reactions in the CO—NO—O2—H2O system on a Pt/γAl2O3catalyst. At fixed space-velocity and catalyst temperature, and for fixed reactor inlet concentrations of CO and NO. there is negligible CO—NO reaction either in the absence of oxygen or in the presence of excess oxygen. However, short of the stoichiometric amount of O2required for CO oxidation, there is appreciable CO—NO (and possibly also CO—NO—H2O) reaction whose extent increases with increasing oxygen concentration. This increase is especially dramatic in a narrow window of O2: concentrations near the stoichiometric point. Interestingly enough, near the stoichiometric point, self-sustained isothermal oscillations in the outlet CO and NO concentrations are also observed (Subramaniam and Varma. submitted for publication)

ISSN:0098-6445    

DOI:10.1080/00986448308940583

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A completely consistent theory of the cmc (critical micelle concentration) for nonionic and ionic micelles is described. Micellization is treated as a critical phenomenon using classical, thermodynamic nucleation theory modified to take into account a variable surface tension. The micelles are described as small oil droplets which have to surpass a critical size (the critical micelle) in order to have micellization. The driving force is the “supersaturation” of hydrocarbon chains in aqueous solution, i.e. hydrophobic forces. Real phase separation is prevented, however, because of the accumulation of head groups on the micellar surface. This accumulation leads eventually to zero or negative interfacial tension and dissolution of the micelles by Brownian motions.

ISSN:0098-6445    

DOI:10.1080/00986448308940584

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor