Predicting the Liquid Phase Mass Transfer Resistance of Structured Packings

Published correlations for estimating the liquid phase mass transfer coefficients of structured packings are compared using experimental evidence on the efficiency of Montz-Pak B1–250MN and B1–500MN structured packings as measured in total reflux distillation tests using the chlorobenzene/ethylbenzene system at two operating pressures. Large differences are found between different correlations with respect to both the absolute values of mass transfer coefficients and the fraction of liquid phase based resistance and their trends with respect to increasing vapor and liquid loads. A new Delft Model liquid side mass transfer coefficient correlation that incorporates a more appropriate definition of the liquid film exposure length is presented which now generates lower values. The revised liquid film model, combined with an enhanced turbulent vapor phase mass transfer coefficient, leads to doubling the fractional liquid phase resistance with respect to that based on penetration theory assuming equal contact times. This effect results in predicting efficiencies which are slightly more conservative and agree reasonably well with experimental HETP data presented in this paper.Process and EnergyMechanical, Maritime and Materials Engineerin

Augmenting Distillation by Membranes: Developments and Prospects

The growing consciousness for sustainable industrial processes has resulted in industrially developed countries in supporting research efforts toward thorough evaluation of possibilities for improving efficiency of energy intensive separations implying also significant reduction of related carbon dioxide emissions. Being inherently thermodynamically inefficient, distillation, which is by far the most widely utilised and energy intensive separation technology in chemical process industries, has become primary target of energy conservation projects in refining, petrochemical and chemical industries. Improvement is an ongoing activity, replacing still beyond comprehension and a great deal of academic effort is oriented towards augmenting distillation by combining it, where appropriate, with membranes, i.e. pervaporation or vapour permeation, which in conjunction with polymeric membranes proved to be an industrially viable alternative to conventional processes for dehydration of alcohols. Present paper addresses recent developments along this line striving for larger fluxes in alcohol dehydrations by utilising ceramic membranes, with focus on vapour permeation, as well as the potential for the recovery of organic solvents and reactants forming azeotropes with other organics

Augmenting Distillation by Membranes: Developments and Prospects

The growing consciousness for sustainable industrial processes has resulted in industrially developed countries in supporting research efforts toward thorough evaluation of possibilities for improving efficiency of energy intensive separations implying also significant reduction of related carbon dioxide emissions. Being inherently thermodynamically inefficient, distillation, which is by far the most widely utilised and energy intensive separation technology in chemical process industries, has become primary target of energy conservation projects in refining, petrochemical and chemical industries. Improvement is an ongoing activity, replacing still beyond comprehension and a great deal of academic effort is oriented towards augmenting distillation by combining it, where appropriate, with membranes, i.e. pervaporation or vapour permeation, which in conjunction with polymeric membranes proved to be an industrially viable alternative to conventional processes for dehydration of alcohols. Present paper addresses recent developments along this line striving for larger fluxes in alcohol dehydrations by utilising ceramic membranes, with focus on vapour permeation, as well as the potential for the recovery of organic solvents and reactants forming azeotropes with other organics

An Improved Shortcut Design Method of Divided Wall Columns Exemplified by a Liquefied Petroleum Gas Process

Designing a sustainable and economical distillation system is a big global challenge in the industrial chemical field. To address this issue, one of most promising solutions is the so-called dividing wall columns addressed in this work, which not only can cut energy cost but also use limited installation space. An improved shortcut design approach is developed in this work to provide accurate models for each section of dividing wall columns; meanwhile Underwood’s and Gilliland’s equations are employed to determine minimum reflux ratio and total number of stages in different column sections in terms of corresponding design specifications and operating conditions. This proposed approach has been applied to separations of mixtures of hydrocarbons and alcohol with different values on the ease of separation index. To test its effectiveness, the preliminary design parameters obtained through the improved proposed shortcut method are further validated by a rigorous simulation in Aspen HYSYS. Furthermore, the results indicate that this method could provide much more accuracy of average interconnecting stream composition of the prefractionator and main column than those of other methods. In practice, this method has been applied to a case of liquefied petroleum gas (LPG) separation with three targeted products in an industrial liquefied petroleum gas plant. The applications and efficiency of the shortcut method in this study lay a theoretical foundation for designing the separation of ideal mixtures involving dividing wall columns

A next generation, pilot-scale continuous sterilization system for fermentation media

A new continuous sterilization system was designed, constructed, started up, and qualified for media sterilization for secondary metabolite cultivations, bioconversions, and enzyme production. An existing Honeywell Total Distributed Control 3000-based control system was extended using redundant High performance Process Manager controllers for 98 I/O (input/output) points. This new equipment was retrofitted into an industrial research fermentation pilot plant, designed and constructed in the early 1980s. Design strategies of this new continuous sterilizer system and the expanded control system are described and compared with the literature (including dairy and bio-waste inactivation applications) and the weaknesses of the prior installation for expected effectiveness. In addition, the reasoning behind selection of some of these improved features has been incorporated. Examples of enhancements adopted include sanitary heat exchanger (HEX) design, incorporation of a “flash” cooling HEX, on-line calculation of F(o) and R(o), and use of field I/O modules located near the vessel to permit low-cost addition of new instrumentation. Sterilizer performance also was characterized over the expected range of operating conditions. Differences between design and observed temperature, pressure, and other profiles were quantified and investigated