Hausen and Murphree efficiencies in binary and multicomponent distillation

The design of industrial distillation columns is normally based on estimated values of plate efficiencies. Several different plate efficiency models have been proposed in the literature and among them the one presented by Murphree is widely used in spite of its limitations. However the difficulties involved in the use of Murphree's model are not present if Hausen's model is considered.In the present paper a comparative study of the two models considering both binary and multicomponent systems is presented. A graphical relationship beExperimental composition profiles obtained in small laboratory columns with binary and ternary systems are interpreted in terms of Hausen efficiencies.It is argued that the use of the Hausen efficiency model should be wider as it overcomes limitations of Murphree's model and is in agreement with physi     

Channel-collapse effect examined with laboratory equipment and by two-dimensional calculation

Combustion, Explosion, and Shock Waves -     

Production of high-alumina cement clinker by fusion in an electric furnace

Conclusions The possibility of obtaining clinker from high-alumina cement by melting a mixture of lime and technical alumina in an electric-arc furnace at the Klyuchevsk Ferroalloy Plant has been shown.The high-alumina cement obtained from fused clinker is significantly better in its physicochemical properties than the cement produced on the basis of the lime-alumina slags from the ferroalloy industry.Translated from Ogneupory, No. 5, pp. 25–27, May, 1984.     

Structure formation in production of yttrium-silicate materials by the sol-gel method

Materials made from yttrium silicates were synthesized by the sol-gel method. The effect of the amount of yttrium oxide, which varied from 10 to 50% (molar content), and the water:alcoholate molar ratio was investigated. Structure formation and the character of crystallization of gels in heat treatment in the 650–1300°C range were investigated. __________ Translated from Steklo i Keramika, No. 1, pp. 3–6, January, 2007.     

Hydrosilylation and dehydrocondensation reactions of methylhydridesiloxane to acrylic and methacrylic acids

The hydrosilylation of α,ω‐bis(trimethylsiloxy) methylhydridesiloxane (degree of polymerization ≈ 53) with acrylic and methacrylic acid with various ratios of the initial compounds, in the presence of platinum hydrochloric acid, has been investigated. In the presence of platinum hydrochloric acid, competitive dehydrocondensation reactions take place with the formation of various oligomers with various chemical links. In the later stages of the reaction, three‐dimensional systems have been obtained. During dehydrocondensation, the reaction order, reaction rate constants, and activation energy have been determined. The structures of the synthesized oligomers have been determined with IR and NMR spectroscopy data. Gel permeation chromatography, differential scanning calorimetry, and X‐ray analyses of the synthesized oligomers have been carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3243–3252, 2007     

Statistical evaluation of the effect of the mold temperature on the strength of glass containers

Using methods of mathematical statistics (cluster, dispersion, and correlation analyses), the impact strength of three types of glass containers (bottles and jars) was analyzed. Three temperature regions in which molding results in very different values of the strength of the articles are revealed. The boundaries of the molding temperature regions are critical regardless of the type of article molded and are probably only determined by the chemical composition of the glass melt. The preferred mold temperature range is 480–550°C. The results of the study are interpreted based on an analysis of the features of molding glass at different temperatures. __________ Translated from Steklo i Keramika, No. 2, pp. 3–7, February, 2007.     

On the critical molecular chain length of polydimethylsiloxane

Because a study of the results reported for the chain dimensions of polydimethylsiloxane (PDMS), critical for the onset of this polymer's non-Newtonian flow behavior, obtained from the viscosity-molecular weight relationships available from the literature, clearly revealed that considerable differences exist between the reported data, a detailed analysis of these data was performed together with an additional examination of 10 new PDMS samples that were selected so as to have molecular weights that would fill the gaps observed in the polymer viscosity–chain length relationship constructed from the accepted literature data. The results obtained were analyzed by using several different procedures integrated into a recently described comparative method that could allow for determination of what is called the most realistic critical value, Z_wc. The latter was determined as 930 PDMS main-chain atoms, which corresponds to this polymer's degree of polymerization of 464.5 and the weight-average molecular weight of 34,500. It is not only shown that after elimination of some clearly erroneous data points from the previously reported relationships the obtained critical chain-length values could very well fit the earlier relationships, but also that appropriate “master” relationships were constructed including 48 pairs of the old and 10 pairs of the new data points. It is suggested that this relationship be accepted as the best-fit viscosity–polymer chain-length dependence for PDMS, and it is pointed out that the obtained PDMS critical chain-length value ranks this polymer's macromolecules as the most flexible of the corresponding long-chain molecules presently known. © 1993 John Wiley & Sons, Inc.