Falling Film Molecular Distillation Research Articles

Separation of Free Fatty Acid and Triglycerides by Molecular Distillation–Experimental and Simulation Approaches

Separation of free fatty acids and triglycerides is important in the edible oil industry. In this study, both experimental and simulation approaches were conducted using falling film molecular distillation. A binary mixture of oleic acid as free fatty acid with refined soybean oil as triglyceride was used. Evaporation temperature range tested was from 110 to 160 °C, while other parameters such as condensation temperature, feeding rate, and vacuum pressure were fixed. The free fatty acid content of retentate was gradually decreased as evaporation temperature increased, while the free fatty acid content of distillate was approximately 100 wt.%, regardless of temperature. Triglycerides had an extremely low vapor pressure compared to oleic acid; therefore, their fraction in distillate was negligible. The mass conservation and transport equations were selected to explain the evaporation mechanism, and analytical solutions were simply introduced under the conditions of low mass fraction of volatile compound in the feeding mixture. Some experimental data are re-quired to determine the coefficient of molecular distillation in the governing equation. Using this obtained parameter, the proposed model could simulate all mass amounts and fractions of each component in retentate and distillate with a good agreement between experimental and simulation data, indicating the reasonable accuracy of the model proposed.

Fractionation of polyethylene wax by pilot-scale molecular distillation: new insights on process development

A falling film molecular distillation (FFMD) process was used in a pilot plant to fractionate a polyethylene wax (PE-Wax) into light paraffin wax (LP-Wax) and super-microcrystalline wax (SM-Wax). The pseudoization technique was applied to represent the molecular distribution of the PE-Wax by pseudo-components (PS1 and PS2). Investigation was made of the influences of the evaporator temperature (EVT), feed flow rate (FF), and condenser temperature (CT) on the percent recovery of distillate (DP), the yield of PS1 in the distillate (YD_PS1), and the distillate flow rate/feed flow rate ratio (DF). The predictive models and the multi-response optimization provided decision criteria about the most suitable operating conditions for fractionating PE-Wax. The best experimental data for DP,YD_PS1, and DF (63.4%, 81.5%, and 0.60, respectively) were obtained with EVT of 184°C, FF of 1.81kg/h, and CT of 28°C, at 0.1Pa. The LP-Wax, recovered mainly in the distillate, exhibited a normal distribution throughout the carbon number range from n-C13 to n-C30. The SM-Wax, recovered in the residue, showed a higher latent heat of storage (>169kJ/kg), according to the phase-change performance of the material. These results offer new insights into processing PE-Wax to obtain value-added products with narrower carbon number distributions.

Fractionation and Characterization of a Petroleum Residue by Molecular Distillation Process

In this work, an atmospheric petroleum residue was fractionated using a falling film molecular distillation pilot plant with molecular distillation temperatures ranging from 190 to 320 °C. The process produced four distillate cuts and four residues that were characterized in order to evaluate the efficiency of the technique. The results showed a gain of 11.7% in distillate yield in the highest molecular distillation temperature studied. Physicochemical characterization of the fractions demonstrated that complex compounds were separated of the distillate cuts and were concentrated in the residues which have compounds with features of resins and asphaltenes. Furthermore, data from molecular distillation experiments were used to extend the true boiling point curve of the crude oil up to 662 °C with continuity and good agreement with the ASTM curves.

Evaluation of Atmospheric and Vacuum Residues Using Molecular Distillation and Optimization

The term atmospheric residue describes the material at the bottom of the atmospheric distillation tower having a lower boiling point limit of about 340°C; the term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent boiling point (AEBP) above 540°C. In this work, the objective is to evaluate the behavior of different kinds of Brazilian atmospheric and vacuum residues using molecular distillation. The Falling Film Molecular Distillator was used. For the results obtained through this process, a significant range of temperature can be explored avoiding the thermal decomposition of the material. So these results are very important to the refinery decisions and improvements. The Experimental Factorial Design results showed that the temperature has more influence on the process than the feed flow rate, when a higher percentage of distillate is required.

True Boiling Point Extended Curve of Vacuum Residue Through Molecular Distillation

Molecular distillation is a separation process that explores high vacuum, operation at reduced temperatures, and low exposition of the material at the operating temperature. The term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent temperature (AET) above 540°C. For the assay of the properties of petroleum and petroleum products, the use of the true boiling point (TBP) distillation analysis is accepted as a common practice; however, for heavy petroleum fractions, some difficulties appear for determination of TBP of these petroleum fractions. The objective of this work is to develop a new and a more appropriated method to extend the TBP curve to use it for characterizing vacuum residue of heavy petroleum. The falling film molecular distillator was used. The results showed that it is possible to extend the TBP curve through molecular distillation process with very good precision.

Modeling of Falling Film Molecular Distillator

On the basis of the kinetic equation, a mathematic model for two‐components in the presence of an inert gas was developed to describe the falling film molecular distillation process. The heat and mass transfer in liquid film on the evaporating surface and the mass transfer in the vapor phase in the distillation gap are taken into account. This model may show the profiles of temperature and concentration of film and the profiles of density, temperature, and velocity of vapor in consideration of the feed rate, evaporation temperature, and inert gas pressure. The model can be applicable to simulating various operational situations in a falling film molecular distillator. The comparison of the experiment results with the model study results shows a satisfactory qualitative agreement between the experiment and the theory.

Evaluation of tocopherol recovery through simulation of molecular distillation process.

DISMOL simulator was used to determine the best possible operating conditions to guide, in future studies, experimental works. This simulator needs several physical-chemical properties and often it is very difficult to determine them because of the complexity of the involved components. Their determinations must be made through correlations and/or predictions, in order to characterize the system and calculate it. The first try is to have simulation results of a system that later can be validated with experimental data. To implement, in the simulator, the necessary parameters of complex systems is a difficult task. In this work, we aimed to determe these properties in order to evaluate the tocopherol (vitamin E) recovery using a DISMOL simulator. The raw material used was the crude deodorizer distillate of soya oil. With this procedure, it is possible to determine the best operating conditions for experimental works and to evaluate the process in the separation of new systems, analyzing the profiles obtained from these simulations for the falling film molecular distillator.

Production and use of natural antioxidants

AbstractWe have developed a new industrial process for obtaining natural antioxidants from spices and other vegetables by primarily adapting mechanical and physical treatments. Rosemary, sage, paprika, nutmeg and cocoa shells have been submitted to a mechanical treatment (micronization), and the finely powdered material was extracted with an edible vegetable oil, i.e., groundnut. The antioxidant dissolved in the lipid phase was collected by two‐stage falling film molecular distillation to separate the lipid phase to be recycled) from the active, low molecular weight fraction. Antioxidant activity was measured for fats, oils and fat‐containing foods by oxygen absorption, head‐space analysis (i.e., pentane) extent of secondary degradation products and organoleptic evaluations. Results obtained indicate that molecular distillates from spices, i.e., rosemary derivatives, effectively protect foods against oxidative rancidity.

Quantitative recovery of volatiles from fats and oils by combined high vacuum degassing and thin film molecular distillation

AbstractAn apparatus is described which in one unit combines conventional high vacuum degassing on cold finger with falling film molecular distillation. The upper part of the cold finger is for the collection of the most volatile substances, while the lower part is for the condensing of substances which are molecular distilled from a wiped falling film. All the connections in the glass apparatus are made from Teflon or Viton‐O‐rings, and the turning of the rotor in the molecular distillation part is carried out by means of a magnetic coupling. In this way, the risk for contamination is reduced greatly. As all volatile substances after the treatment of the oil are on the same cold finger, the collection can be made by a high vacuum distillation into a small glass chilled with liquid nitrogen. In the bp range of 40–450 C, the apparatus gives recoveries of volatiles in or below the ppm range between 71–114% with coefficients of variance between 5–23%. The recoveries are found with internal standards added before treatment of the oil. Below 70 C, the recoveries drop to some extent. The volatiles are substances with different kinds of functional groups, e.g. hydrocarbons, aldehydes, ketones, acids, esters, lactones, and sulfur containing substances.

429. Mass transfer in falling-film molecular distillation: H. Uyeha, T. Shigemaaa, Y. Tozaki and A. Oyeha, Chem. Eng., Japan, 24, 281–288, 1960

429. Mass transfer in falling-film molecular distillation: H. Uyeha, T. Shigemaaa, Y. Tozaki and A. Oyeha, Chem. Eng., Japan, 24, 281–288, 1960