Energy and Exergetic Evaluation of the Multicomponent Separation of Petrochemical Naphtha in Falling Film Distillation Columns

Abstract

Multicomponent separation of synthetic petrochemical naphtha (hexane, cyclohexane, toluene and xylene) was carried out in a falling film distillation sequence with heat supply using a vapor chamber (thermosyphon). Tests were carried out by varying feed flow rate and temperatures of the feed and the vapor chamber in two ways of heat supply: isothermal and with a vapor chamber temperature profile. Regarding the distillation behavior of the multicomponent separation with the proposed falling film column, it was verified that the lower values of the studied variables and the profile temperature mode promoted the best results for hexane recuperation. With an indirect sequence of three columns, hexane mass fraction in the top column increases to the value of 0.82. Higher thermodynamic efficiency was found for two columns of the sequence in comparison with the conventional ones. This behavior is related to smaller energy consumption, showing a total energy reduction of 12% compared to the same separation performed in a conventional unit. Energy and exergetic efficiency values were higher than 95% and 85% in the three columns used. These analyses demonstrated that the falling film separation proposal is an energy efficient arrangement and could be considered for multicomponent separation.

Film Thickness and Glycerol Concentration Mapping of Falling Films Based on Fluorescence and Near-Infrared Technique

“…After determining the regression coefficients, the glycerol mass concentration per pixel follows from Equation (12). For this purpose, the corresponding VIS image of the falling film was the input to find the appropriate coefficients in the coefficient matrix for the calculation.…”

“…Specifically, the film thickness images were converted into a matrix, and the measured values were used sequentially to search the coefficients. The exact pixel position is searched and read out in each absorbance image and the calculation was performed according to Equation (12). Then, the result matrix is converted back into an image and displayed in false colors.…”

“…Gentle partial evaporation of the product medium is decisive for product quality, and falling film evaporators are used for this purpose, especially in industrial processes like food production and the evaporation of sucrose solutions [1,2], milk, and fruit juices [3][4][5][6][7][8]. Other applications include solvent separation from oligomers or polymers [9][10][11], separation of petrochemical naphtha [12], and dewatering of ionic liquids [13][14][15].…”