Experimental study on mechanical filtration through tobacco columns: Influence of cut-filler shape and size distribution on filtration efficiencies

Tobacco columns are extreme examples of heterogenous packed beds, which have various cut-filler shapes and a wide range of size distribution. The behavior of mechanical filtration through tobacco columns has been investigated by using polystyrene latex (PSL) standard particles to compare the actual filtration efficiency with the predicted filtration efficiency calculated by theoretical equations for spherical packed beds. The influence of cut-filler shape and the range of cut-filler size distribution on filtration efficiency have been examined. The effect of diffusion in tobacco columns was lower and the effect of interception and inertia were higher than in spherical packed beds. These results show that a partially faster flow could have occurred in tobacco columns. It means that it is difficult to utilize the theoretical equations for spherical packed beds to heterogenous packed beds as proposed. Filtration efficiency through tobacco columns had a relationship with the factor that shows cut-filler shape and size distribution (r = 0.894, p < 0.05) and the factor that shows cut-filler size distribution (r = 0.683, p < 0.15). The factor showing cut-filler shape and size distribution was expected to be an effective factor of filtration efficiency for heterogenous packed beds. From these experiments, empirical equations that can be applied to tobacco columns have been proposed, and the prediction accuracy during burning was validated. It has been found that the prediction accuracy was precise, revealing the importance of taking the influence of cut-filler shape and size distribution into account in the filtration equations.

Copyright © 2016 American Association for Aerosol Research     

导向浮阀塔板在醋酸生产中的应用

导向浮阀塔板是在F1型浮阀塔板的基础上开发成功的，较早应用于炼油装置的常减压蒸馏塔，在提高轻油的收率上获得了较大的经济效益，在化工产品的分离中应用较少。该项目在醋酸装置的精馏工序中，采用先进的导向浮阀塔板改造原有的F1型浮阀塔板，达到节能降耗，提高醋酸收率，增加醋酸产量，提高经济效益的目的。     

The continuous phase heat and mass transfer properties of dispersions

Techniques have been developed for measuring the interfacial area in gas-liquid dispersions. It has thus been possible to measure the liquid-phase mass transfer coefficients in gas-liquid dispersions such as are produced in aerated mixing vessels, and sieve and sintered plate columns. The results have been combined with other published data for heat and mass transfer in liquid-liquid and solid-gas dispersions in which the dispersed phases are free to move under the action of gravity, and also with data on transfer by free convection from spheres. These data can all be correlated by

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Soil carbon,soil nitrate,and soil emissions of nitrous oxide during cultivation of energy crops

Carbon (C) sequestration and soil emissions of nitrous oxide (N₂O) affect the carbon dioxide (CO₂) advantage of energy crops. A long-term study has been performed to evaluate the environmental effects of energy crop cultivation on the loamy sand soil of the drier northeast region of Germany. The experimental field, established in 1994, consisted of columns (0.25 ha each) cultivated with short rotation coppice (SRC: Salix and Populus) and columns cultivated with annual crops. The columns were subdivided into four blocks, with each receiving different fertilization treatments. The soil C content was measured annually from 1994 until 1997, and then in 2006. Soil N₂O levels were measured several times per week from 1999 to 2007. Water-filled pore space (WFPS) and soil nitrate measurements have been performed weekly since 2003. Increased C stocks were found in SRC columns, and C loss was observed in blocks with annual crops. The soil from fertilized blocks had higher levels of C than the soil from non-fertilized blocks. SRC cropping systems on dry, loamy sand soils are advantageous relative to annual cropping systems because of higher C sequestration, lower fertilized-induced N₂O emissions, and reduced background N₂O emissions in these soils. SRC cropping systems on dry, loamy sand soils have a CO₂ advantage (approximately 4 Mg CO₂ ha⁻¹ year⁻¹) relative to annual cropping systems.     

High-resolution gas chromatographic determination of alkanols in oils extracted from olives

Polar columns with stationary phases characterized by high thermal stability have attracted a great deal of interest in the study of lipid compounds that have, until recently, been studied with nonpolar columns. Such polar columns have also proved useful in the study of the entire unsaponifiable matter of a lipid and in determining the alkanols of extra-virgin olive oil, husk oil and their relative mixtures. The proposed procedure permits the study of alkanols without having to isolate them from the other classes of compounds present in the unsaponifiable matter by means of thin-layer chromatography.     

Simulation and design of distillation units for treatment of sulfite pulping condensates to recover methanol and furfural: Part II: Applicability of multiple-effect distillation using live steam

A distillation unit has been designed for a capacity of 73 t/h of condensate and for at least 90% recovery of the contaminating organics. This unit consists of three columns: a primary stripper to remove volatile organics and two upgrading columns to purify the methanol and furfural byproducts. Three different energy-saving alternatives for satisfying the energy requirements have been studied: utilisation of secondary steam from the evaporation plant, and application of the principle of multi-effect distillation in one-stripper and in two-stripper configurations. Investment cost needed in all alternatives amounts to 5.5–6.0 MCr (millions of Swedish Crowns) while operating cost varies between 0.8–3.1 MCr. The first design alternative has a payoff period of 2.3 years while the two multi-effect distillation alternatives have a payoff period of about 3 years.     

Determination of the Solid Fat Content in Milk Fat by Gas Chromatographic Triglyceride Analysis

Milk fat from 440 butter samples obtained from more than 20 Northern German milk collection areas was extracted and the solid fat content (SFC) determined at 7 temperatures between 0 and 30°C using nuclear magnetic resonance spectrometry. Further, all milk fats were analyzed gas chromatographically for their triglyceride composition. Using a multiple regression analysis triglyceride formulae have been computed which enable the SFC-values to be theoretically calculated at all 7 measuring temperatures. The standard deviations between experimental and theoretical SFC-values at temperatures between 0, 5…, 30°C ranged between 0.88 and 0.38% (r = 0.99990 and 0.99682). Also between the fatty acids C18:1 (oleic acid with isomers), C16 (palmitic acid) resp. C16/C18:1 and the SFC-values measured at 0°C relationships have been established (r = -0.95, 0.93 and 0.93, respectively). Since the expenditure in time necessary for gas chromatographic triglyceride analysis by using simultaneously 2 columns can be reduced to 4 - 5 min and, in addition, extrelut columns allow a very fast isolation of fat from milk for gas chromatographic analyses, rapid characterization of milk fat regarding solid fat contents or also milk fat hardness is feasible by means of triglyceride analysis. Besides the SFC-values a number of other milk fat parameters, such as iodine number, melting point, refraction index etc. can be determined using the same triglyceride analysis.     

Some Contemporary Applications of Open-Tubular Gas-Liquid Chromatography in Analyses of Methyl Esters of Longer-Chain Fatty Acids

The application of wall-coated open-tubular (capillary) gasliquid chromatographic columns to some current analytical problems in fat research is described. The liquid phase SILAR-5CP in commercially available stainless steel columns has been found to be particularly suitable for rapid screening of fats and oils for total docosenoic acid without interference from other components. Differentiation of two important 22:1 isomers (erucic acid from vegetable oils and cetoleic acid from marine oils) is possible and the erucic acid content of an oil or fat can be estimated in approximately 20 minutes. The effects of partial hydrogenation of fats on the gas-liquid chromatography of these fatty acid structural details are reviewed. The use of other liquid phases such as butanediolsuccinate polyester, and the advantages of SILAR-7CP for study of geometrical isomers in wall-coated open-tubular columns are discussed briefly, and also the potential of support-coated open-tubular columns for similar analyses of longer-chain fatty acids.     

THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN FLAT-PLATE THERMAL DIFFUSION COLUMNS OF THE FRAZIER SCHEME

The effect of plate spacing on the degree of separation and production rate in flat-plate thermal diffusion columns of the Frazier scheme with fixed operating expense, has been investigated. The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate have been developed. Considerable improvement in performance is obtainable when the thermal diffusion columns with optimum plate-spacing are employed for operation.     

Recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with optimum plate-spacing

The effect of plate-spacing on the degree of recovery and production rate for the recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with fixed operation expense has been investigated. The equations for estimating optimum plate-spacing for maximum recovery and maximum production rate have been developed. Considerable improvement in performance is obtainable when thermal-diffusion columns with optimum plate-spacing are employed for operation.     

高效液相色谱手性固定相法拆分O，O-二甲基-1-（苯氧乙酰氧基）乙基膦酸酯和O，O-二甲基-1-（4-甲基苯氧乙酰氧基）乙基膦酸酯对映体

在直链淀粉-三-(3,5-二甲基氨基甲酸酯)(Chiralpak AD-H)手性柱上对O,O-二甲基-1-(苯氧乙酰氧基)乙基膦酸酯和O,O-二甲基-1-(4-甲基苯氧乙酰氧基)乙基膦酸酯对映体的分离进行了研究。分别考察了流动相极性改良剂的类型和比例以及温度对拆分效果的影响,并初步讨论了拆分的热力学机理。实验结果显示:流动相为正已烷-异丙醇(体积比90∶10),流速为1.0mL/min,检测波长220nm,温度25℃,O,O-二甲基-1-(苯氧乙酰氧基)乙基膦酸酯和O,O-二甲基-1-(4-甲基苯氧乙酰氧基)乙基膦酸酯在Chiralpak AD-H柱上分离度Rs分别为2.63、1.56,对映体都可得到满意的基线分离。     

Rigorous design of distillation columns using surrogate models based on Kriging interpolation

The economic design of a distillation column or distillation sequences is a challenging problem that has been addressed by superstructure approaches. However, these methods have not been widely used because they lead to mixed‐integer nonlinear programs that are hard to solve, and require complex initialization procedures. In this article, we propose to address this challenging problem by substituting the distillation columns by Kriging‐based surrogate models generated via state of the art distillation models. We study different columns with increasing difficulty, and show that it is possible to get accurate Kriging‐based surrogate models. The optimization strategy ensures that convergence to a local optimum is guaranteed for numerical noise‐free models. For distillation columns (slightly noisy systems), Karush–Kuhn–Tucker optimality conditions cannot be tested directly on the actual model, but still we can guarantee a local minimum in a trust region of the surrogate model that contains the actual local minimum. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2169–2187, 2015     

适用于分批精馏和多用途填料塔的液体分布器

介绍两种适用于分批精馏及多用途填料塔的液体分布器——槽式和双排管式高弹性液体分布器。目前通用型液体分布器的操作弹性一般为4:1,而这种液体分布器,其操作弹性可达10:1左右。本文提出的小孔排量计算方法同样也适用于大型填料塔的液体分布器。     

复杂精馏塔的设计型算法

本文建立了用于复杂精馏塔(可有多股进料、汽、液相侧线出料和中间换热器的塔)的设计型算法.本算法可根据指定的独立变量值,通过优化计算确定能满足各项设计指标的一组优化设计参数值.本算法应用SHBWR(BWRS)及PR汽-液平衡和焓模型对金山乙烯装置中的典型塔等进行了考核,取得满意的结果.     

Gel permeation chromatography calibration based on fractal geometry

The previously developed model [Polym Bull 2000, 44, 525] used to characterize the porous gel inside a gel permeation chromatography (GPC) column, has been extended to also include the interstitial space between the macroscopic gel particles. The hydrodynamic dimensions for 12 polystyrene (PS) standards, measured by GPC with differential refractive index (DRI), differential viscometry (VISCO), and multiangle laser light scattering (MALLS) detectors, have been used to determine the fractal parameters of the polystyrene–divinylbenzene gel corresponding to four commercial columns. The new developed model enables to predict the calibration curve for the sets of coupled columns based on the parameters of each column. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 771–777, 2004     

Heat consumption and irreversibilities in rectification processes

Chemical engineering analysis using entropy production has been proven to be an essential tool to identify areas in chemical plants, where degradation of energy occurs. Though, applied very extensively in the area of heat exchanger networks in the form of “pinch technology”, the method is rarely used with respect to processes with mass energy. Entropy productions in destillation columns have been evaluated and discussed with respect to feed introduction, sequences of columns and other technically important features.     

热耦蒸馏技术进展

热耦蒸馏作为一种新型蒸馏技术,与常规蒸馏相比,热耦蒸馏平均可节省能耗30％左右,同时还可降低设备投资。本文介绍热耦蒸馏塔的构造、分类、特点以及设计和应用。     

Entwicklung einer präzisen Kapillar-GC-Methode zur schnellen Triglyceridanalytik von Milchfetten

Development of a Precise Capillary GC Method for Rapid Triglyceride Analysis of Milk Fats Quantitative analysis of triglycerides - partly in conjunction with triglyceride formulae - can be used for the gas chromatographic determination of various milk fat parameters. Since these examinations, for example the evaluation of the content of foreign fats in milk fat, require only the separation of triglycerides by carbon number and since the repeatability of analytical results, especially of the high-boiling triglycerides, has been worse with capillary columns in the past, packed columns have been used mostly. With respect to the increasing application of triglyceride formulae and the related demand for the use of capillary instead of packed columns extensive investigations have been carried out to that end now. For the development of this exacting high-temperature application a particularly temperature-stable metal capillary column was used. The effects of varying the temperature program, the carrier gas flow, the injection technique as well as the sample concentration on the resolution are demonstrated. Finally, the optimizing led to results that are comparable to those achieved by packed columns with regard to resolution and precision. Thus, the rapid gas chromatographic determination of milk fat parameters can now be carried out with a standardized capillary column as well.