Separation Flowsheet Research Articles

Separation and purification of ethyl acetate from its reaction mass: proposal for downstream distillation sequence and validation

ABSTRACT This work has performed simulation and experimentation of separating the reaction mixture of the ethyl acetate manufacture by Fischer esterification. Assuming stoichiometric proportion of reactants, mixture with equilibrium composition was subjected to separation. Simulation in the Aspen plus environment using RadFrac module with EQ model was performed. To obtain a range of parameters and variables, sensitivity analysis was performed. Economic analysis was also performed. Experimentation was done to verify the results of simulation using distillation and extractive distillation to obtain the streams with highest purity and unreacted reactants were separated into pure form. A complete flowsheet for separation and purification is suggested.

Selective Separation of Lithium from Leachate of Spent Lithium-Ion Batteries by Zirconium Phosphate/Polyacrylonitrile Composite: Leaching and Sorption Behavior

This study introduces a straightforward and effective amorphous ZrP/polyacrylonitrile composite ion exchange method for separating Li from the leachate of spent Li-ion batteries (NMC 111). The cathode materials were leached with a series of optimized experiments. The influence of operating variables, including the H2SO4 concentration, temperature, H2O2 concentration, and pulp density, on leaching efficiency was examined to determine the optimal conditions for sorption experiments. The leaching efficiencies of Li, Co, Ni, and Mn were found to be 99.9%, 99.5%, 98.8%, and 99.9%, respectively. Subsequently, batch sorption experiments were performed by using am-ZrP/PAN, including the determination of the effect of pH, sorption kinetics, and the sorption isotherm. The effect of pH on adsorption was examined in 1 mmol/L equimolar solutions of Li, Ni, Mn, and Co. Li was separated from Mn, Co, and Ni in the leaching liquor. The adsorbent for Mn, Co, and Ni sorption better fitted pseudo-second-order kinetics. High selectivity for Li was observed, even at the higher solution concentration of 15 mM Li, Ni, Co and Mn. In addition, the column loading process demonstrated selectivity for Li over Co, Ni, and Mn metal ions. The preliminary evaluation of the whole process with mass flow demonstrated that it would be feasible to achieve full separation and metal recovery by integrating a combined hydrometallurgical method in future studies. However, much work is still needed to develop a practical separation flowsheet.

Flowsheets for hydroxyacetone–phenol binary mixture separation: The use of special distillation methods

Objectives. To study the possibility of hydroxyacetone–phenol binary mixture (a constituent of a mixture of phenol production by the cumene method) separation in flowsheets based on the use of distillation special methods. This is the addition of separating agents to increase the relative volatility of the components of the original mixture, and the variation of pressure in the columns.Methods. A computational simulation in Aspen Plus® was used as the research method. Mathematical modeling of the vapor–liquid equilibrium was carried out using a local compositions model Non-Random Two Liquid. The viability of the latter was confirmed by comparing experimental and calculated on phase equilibrium data, and azeotropic data. The average relative error does not exceed 3%.Results. The dependence of the composition and boiling point of the hydroxyacetone–phenol azeotrope on pressure was determined in a computational experiment (as the pressure increases, the azeotrope is enriched with phenol). The possibility of using a complex of columns operating under different pressures to separate the mixture was shown (the shift of the azeotrope is about 9%). The change in the relative volatility of components of the original mixture in the presence of a high(diethylene glycol) and a low-boiling (acetone) separating agent was investigated. Both solvents are selective agents used in extractive and re-extractive distillation processes. Three technological separation flowsheets containing two distillation columns were proposed.Conclusions. The study established the operation parameters of the columns (number of theoretical stages, feed stages of the original mixture and separating agent, and reflux ratio) and energy consumption (total heat supplied to the columns boiler) of three separation flowsheets ensuring the production of products of a given quality (not less than 0.99 mol fractions). The flowsheet with diethylene glycol is characterized by the lowest energy consumption. It is recommended that complexes of extractive and re-extractive distillation be further optimized. This enables the second product of cumulus production—acetone—to be involved in the technological cycle.

Comparison of Extractive and Heteroazeotropic Distillation of High-Boiling Aqueous Mixtures

The processes of extractive distillation and heteroazeotropic distillation of mixtures containing water and a high-boiling component (propionic acid, acetic acid, 1-methoxy-2-propanol) are compared. Entrainers declared in the literature as effective agents for these processes were selected as separating agents. A distillation process simulation in AspenPlus V.11.0 is made. Parametric optimization is carried out and the column operation parameters (number of stages, feed stage, reflux ratio) that meet the minimum energy consumptions and ensure the production of marketable substances are determined. It is shown that the process of heteroazeotropic distillation is more energy-efficient compared to extractive distillation by more than 50%, due to the introduction of an entrainer that lowers the boiling point of process. In addition, in some cases (acetic acid + water with vinyl acetate, propionic acid + water with hexane, cyclohexane, cyclohexanol), one of the columns in the separation flowsheet can be abandoned due to the significantly limited mutual solubility.

A new separation flowsheet for resources recovery from waste coal gasification fine slag black water and its benefits analysis

The gasification fine slag black water (GFSBW) is a kind of slurry including fine gasification fine slag particles produced in the coal gasification process and ineffective disposal process causes environmental pollution and resources waste. The aim of this study is to recover combustible matters, high silica-aluminum minerals and water resources via reprocessing GFSBW by innovative separation process of “flotation-agitator-ceramic membrane vacuum (CMV) dewatering”. The physicochemical properties of samples are characterized and at least 6 kinds of carbon-ash occurrence modes of gasification fine slag were found. The flotation process could be a useful method to separate residual carbon and tailing ash. The dewatering processes of flotation slurries are then achieved by the ceramic membrane vacuum filtration, followed by dewatering combustible matters, high silica-aluminum minerals and industrial-water-grade filtrate will be recovered. It is worth noting that the components separation of GFS eliminates their synergistic water holding effect and the average dewatering effect after flotation is improved by 11.67%, and the fixed carbon content of combustible matters is elevated from 22.74% to 44.64%, while the tailing ash including high silica-aluminum minerals is purified to 97.25%. A novel flotation-agitator-ceramic membrane vacuum (CMV) dewatering flowsheet is developed, and useful resources could be recovered to realize waste comprehensive utilization. The proposed GFSBW processing flowsheet could bring 9.82 million US$ per year which is benefit.

Features of distillation separation of multicomponent mixtures

Objectives. To improve the process of developing energy-efficient flowsheets for the distillation separation of multicomponent aqueous and organic mixtures based on a comprehensive study of the phase diagram structures, including those in the presence of additional selective substances.Methods. Thermodynamic-topological analysis of phase diagrams; modeling of phase equilibria in the AspenTech software package using the equations of local compositions: Non-Random Two Liquid and Wilson; computational experiment to determine the column parameters for separation flowsheets of model and real mixtures of various nature.Results. The fractionation conditions of the origin multicomponent mixture due to the use of sharp distillation, pre-splitting process, extractive distillation with individual and binary separating agents were revealed. The columns operation parameters and the energy consumption of the separation flowsheets ensuring the achievement of the required product quality with minimal energy consumption were determined.Conclusions. Using the original methods developed by the authors earlier and based on the generalization of the results obtained, new approaches to the synthesis of energy-efficient multicomponent mixtures separation flowsheets were proposed. The provisions that form the methodological basis for the development of flowsheets for the separation of multicomponent mixtures and supplement the standard flowsheet synthesis plan with new procedures were formulated.

Improved design of separation process for the recovery of cyclohexane and sec-butyl alcohol from wastewater

Background: Economically recovering valuable cyclohexane and sec-butyl alcohol from wastewater is an important industrial problem worthy of research and investigation. The available separation flowsheet in open literature was a heat pump assisted four-column scheme combining heterogeneous azeotropic and extractive distillation. However, the above design achieves significant energy saving at the cost of huge capital investment and increased operational complexity involved in the compression system. The purpose of this paper is to develop an improved configuration for separating the ternary system without using the expensive compression system, and it can also significantly improve the economics.Methods: The core design concept of our proposed three separation flowsheets is to fully utilize the advantage of the heterogeneity of the ternary system by introducing the fresh feed into a decanter for natural liquid-liquid splitting and innovatively applying a direct-contact heat exchanger to preheat the fresh feed. Besides, the technologies of dividing-wall column, side-stream extractive distillation and heat integration are also integrated to the heterogeneous azeotropic and extractive distillation for further energy saving.Significant findings: In comparison with the existing design, our final proposed heat-integrated heterogeneous distillation process with two dividing-wall columns can significantly save energy consumption 24.5%, total annual cost 43.6% and CO2 emission 13.2%.

DÜŞÜK TENÖRLÜ MANYETİT CEVHERİNİN MANYETİK AYIRMA VE YERÇEKİMİ İLE ZENGİNLEŞTİRİLMESİ: TANE BOYU ETKİSİ

This study compares the efficiency of different methods in beneficiation of iron ore from Doğanşehir (Malatya) region. It is a low grade ore with 27.43 % Fe content that requires concentration to meet the specifications of blast furnace feed. The ore mainly contains magnetite, ferro-actinolite and magnesioferrite. The collected samples were classified into different size fractions after size reduction and then subjected to different gravimetric and magnetic separation methods for concentration. The results showed that particle sizes affected the concentrations to a large extend, but wet magnetic separation yielded comparably better results than gravimetric methods. A concentrate assaying 65.66 % Fe and 0.38 % K2O+Na2O was obtained with 78.11 % recovery by wet magnetic separation. It was concluded that concentrates meeting blast furnace specifications could be obtained from this low grade iron ore. It was also concluded that the proposed separation flow sheet can be applied to similar low grade iron ores in the region.

Energy-saving distillation flowsheets for crude isopropanol separation with different solvents

Energy-saving distillation flowsheets for crude isopropanol separation with different solvents

Scaling Trivalent Actinide and Lanthanide Recovery by Diglycolamide Resin from Savannah River Site’s Mark-18A Targets

The Savannah River National Laboratory is implementing a separation flowsheet to recover rare isotopes and transplutonium elements from irradiated 242Pu targets known as Mark-18A targets. The Mark-...

Developing Energy-Efficient Technologies for Obtaining Organic Substances Based on a Comprehensive Study of the Reaction and Separation Constituents

This paper presents an analysis of the literature on the complex study of the reaction and separation constituents of technologies for obtaining industrial organic products: cyclohexanone, epichlorohydride, isopropylbenzene, glycols, and methyl isobutyl ketone. Ways that make it possible to reduce energy consumption by replacing solvents or changing the reaction conditions and combining different design variants of both blocks are shown. The dependence of the energy consumption of the separation flowsheet on the operating conditions of the reactor unit is shown using the example of a mixture of methyl isobutyl ketone. The structure of the diagram of an eight-component system is studied and thermodynamic restrictions on the distillation process are determined. The distillation process is calculated (for a separation flowsheet of a fixed structure) for four compositions of the initial mixture (obtained under different operating conditions of the reactor), and the parameters of the column work making it possible to obtain commercial quality products and corresponding to minimal energy consumption are determined.

Separation and Purification of Methyl Isobutyl Ketone from Acetone + Isopropanol + Water + Methyl Isobutyl Ketone + Methyl Isobutyl Carbinol + Diisobutyl Ketone Mixture.

The paper presents the results of the study of phase equilibrium in the system containing acetone, isopropanol, water, methyl isobutyl ketone, methyl isobutyl carbinol, and diisobutyl ketone. Mathematical modeling in AspenPlus V.10.0 was chosen as a method of studying. Thermodymanic-topological analysis was used to analyze the structure of the VLE diagram. The technique of studying the full composition diagram based only on a two-dimensional scan (determining the presence of a three-dimensional separatric manifold and distillation regions) was presented and demonstrated on the example of five components constituent of the mixture. It is shown that, in some cases, it is sufficient to study the two-dimensional scan of the phase diagram to predict its internal structure. Two separation flowsheets based on the use of direct and sharp distillation were considered, and the operating column parameters corresponding to minimum energy consumption were determined. The sharp distillation was proved to be less energy-intensive.

SEPARATION OF DIETHYL ETHER + HEXANE + ETHYL ACETATE + ETHANOL QUATERNARY SYSTEM VIA EXTRACTIVE DISTILLATION

The paper is devoted to the development of diethyl ether + hexane + ethyl acetate + ethanol mixture (solvents of the dihydroquercetine production) separation flowsheets based on the analysis of the structure of the phase diagram. The phase equilibrium of the quaternary system was studied using mathematical modeling in the AspenPlus. The parameters of Non Random Two Liquid model allow reproducing vapor-liquid equilibrium data and azeotropes characteristics with a relative error not exceeding 5%. It was shown that the system was characterized by the presence of three binary azeotropes and the phase diagram was divided into three distillation regions. Based on a literature analysis N-methyl-2-pyrrolidone was selected as a solvent for the extractive distillation. The selectivity of the separating agent was calculated and it was shown that N-methyl-2-pyrrolidone influenced the relative volatility of components to varying degrees. Two flowsheets containing a diethyl ether separation column and two extractive distillation complexes were proposed. The flowsheets differ in the sequence of separation of the components: hexane, ethyl acetate and ethanol. The distillation process was simulated and the operating column parameters (number of stages, feed stage, reflux ratio, solvent to feed volume ratio) were determined. Selected parameters meet the minimum energy consumption. An energy-efficient separation variant was chosen.

A novel technology for the deash of fine coal by an active pulsing air separation system

t is essential to remove gangue minerals associated with coal as they are harmful, and easy to cause environmental problems if the utilization process is not sustainable. To achieve this, various separation technologies including dry separation methods have been developed. As two-thirds of recoverable coal in China is reserved in water-lack areas, the development and research into dry separation methods has attracted more and more interests and also becomes the focus of the presented work. Besides a focusing on beneficiation of −6+3 mm and −3+1 mm coal particles, this paper aimed to propose a novel separation technology, namely the active pulsing air separation system (APASS). The response surface methodology (RSM) was used to investigate the effects of operational parameters, including airflow rate, pulsing frequency and feed rate, on separation results of two narrowly sized coal samples. Experimental results indicated that separation densities of two coals were similar, and the coarse one showed a relatively higher separation precision. Due to the high yield of particles around separation density and collision among particles, separation results were not good enough as the deash degree was only about 10%. To improve the product quality, the primary and secondary separation flowsheet of the active pulsing air separation system is proposed.

Comparison of alternative methods for methyl acetate + methanol + acetic acid + acetic anhydride mixture separation

Objectives. The paper is a comparative analysis of methyl acetate + methanol + acetic acid + acetic anhydride industrial mixture separation flowsheets based on the use of special distillation methods (extractive distillation and pressure-swing distillation). The results obtained illustrate the variability of the structure of the technological separation flowsheet.Methods. Mathematical modeling using the software package Aspen Plus V. 10.0 was chosen as the research method. The simulation was based on the local composition equation NRTL and the Hayden–O’Connell equation of state. The relative uncertainties of phase equilibrium description do not exceed 3%.Results. The vapor–liquid diagram of the quaternary mixture of methyl acetate + methanol + acetic acid + acetic anhydride was studied using thermodynamic topological analysis. It was shown that the system contains one binary azeotrope and is characterized by one distillation region. Although the structure is not complex, there is a possibility of using several methods for mixture separation: pressure-swing distillation, and extractive distillation with different entrainers. Twelve flowsheets with different structure were proposed, and 29 variants of separation were compared.Conclusions. It was shown that the most perspective structure for the separation of a methyl acetate + methanol + acetic acid + acetic anhydride mixture is a combination of distributed sequence separation and extractive distillation.

New flotation flowsheet for recovering combustible matter from fine waste coking coal

Fine waste coking coal (FWCC) is a high-ash-content by-product produced in large quantities during separation of raw coking coal and deposited in open air without treatment, causing environmental hazards and energy waste. The main objective of this study was to recover clean coal with ash content less than 12.5% by reprocessing FWCC at KaiLuan (Group) Limited Liability Corporation (KLLC) via spiral separation, grinding, and flotation processes. First, the physical characteristics of FWCC were investigated using particle-size analyses, washability analyses, and polarizing microscopy. Then, a spiral separator was used to remove materials with high ash content from the FWCC. Subsequently, spiral clean coal was ground in a roll mill for different grinding durations. Finally, flotation separated the products of grinding from the clean coal. Analyses of the physical characteristics showed that the FWCC could be pretreated using gravity in a spiral separator because it had a large amount of high-density materials. 46.28% spiral clean coal with 26.50% ash content was obtained and 53.72% of spiral tailings with 68.94% ash content were removed with a spiral separator under optimal conditions. The following flotation theoretical yield of clean coal increases with the grinding time. However, flotation experiments show that the maximum actual yield of clean coal first increases and then decreases on increasing the grinding time from 3.5 min to 15 min. Approximately 50% clean coal was obtained at grinding times between 3.5 and 5 min. This can be used for metallurgical plants and has economic value. A novel gravity-grinding-flotation separation flowsheet was developed and nearly 24% of the FWCC could be translated into qualified clean coal to realize comprehensive utilization of this waste resource. Engineering practice further confirm that deep processing of FWCC could generate an extra profit of $11.846 million per year for KLLC. These results indicate that deep processing of FWCC is reliable, economical, and promising for the coking coal industry, and therefore, cleaner production of coking coal is feasible.

Phase Equilibrium of Reaction Mixtures for the Production of Epichlorohydrin in the Presence of Solvents

An alternative solvent for the production of epichlorohydrin via the epoxidation of allyl chloride with an aqueous hydrogen peroxide solution over a heterogeneous catalyst based on a granulated titanium-containing zeolite has been selected. The problem of replacing toxic methanol with other solvents, which provide, in particular, a simplification of the separation flowsheet, has been solved. Five water–allyl chloride–epichlorohydrin–solvent–heavily boiling fraction five-component systems have been studied (methanol, ethanol, propanol-1, propanol-2, and butanol-1). A thermodynamic topological analysis of phase equilibrium diagrams and an assessment of the possibility and feasibility of separating the mixtures via a method based on a combination of distillation and splitting have been conducted. The most promising solvent for the allyl chloride epoxidation reaction is propanol-2.

Recovery of nickel and molybdate from ammoniacal leach liquors of spent HDS catalysts using chelating ion exchange resin

Spent hydrodesulphurization (HDS) catalysts containing valuable Mo and Ni ions are potential source for the recovery of Mo and Ni from the point of commercial, environmental and conservation of natural mineral resources. In the present study, oxidative roasting of spent HDS catalyst followed by ammonia leaching results in the leach liquor with about 15.3 g/L Mo (~85% recovery), ~125 g/L (NH4)2SO4 and ~0.9 g/L Ni as impurity. Therefore Ni separation from this ammoniacal molybdate leach liquor is essentially the first step to obtain high pure molybdate and ammonium sulfate solution. In this study, separation of nickel from ammoniacal molybdate leach liquor was reported using commercial chelating iminodiacetate resin, Lewatit TP207 by batch and column methods. Optimization of process parameters include equilibration time, acidity of leach liquor, aqueous flow rate, metal concentration, loading capacity of resin for Ni during sorption of Ni, desorption of nickel from loaded resin and stability and reuse of resin in continuous column experiments. Feed leach liquor of pH >8.0 is important to achieve clear separation of Ni from Mo. Loading capacity of resin and break through curves are optimized to achieve <10 mg/L Ni in purified Mo leach liquor and further processing results in high grade ammonium octamolybdate (AOM) and ammonium sulfate crystals. Finally, a process flow sheet for the complete separation and recovery of Ni, Mo and ammonium sulphate with material balance from ammoniacal molybdate leach liquor of spent HDS catalyst was demonstrated for possible industrial application.

Energy Savings in Flowsheets based on Combination of Distillation and Splitting Processes

The relationship between structures of ternary systems phase diagram, separation flowsheets including distillation columns and decanters and their energy consumption are discussed. Phase equilibrium diagrams of two ternary systems cyclohexanol + cyclohexanone + water and propanol-1 + cyclohexane + acetonitrile were studied. A number of isomeric flowsheets were proposed for separation of the first ternary mixture and the influence of devices (columns and decanters) arrangement on the flowsheets energy consumption were shown. The influence of separation conditions in a distillation column (the ratio of distillate and bottom flows) on the energy consumption of separation flowsheet were demonstrated on the example system propanol-1 + cyclohexane + acetonitrile.

SYNTHESIS OF FLOWSHEETS FOR SEPARATION OF MULTIPHASE MIXTURES: STATE OF THE ART

The paper presents an analysis of the current state of research on separation flowsheets based on the combination of distillation and phase separation processes, as well as heteroazeotropic distillation. It is shown that the works of foreign researchers devoted to the study of flowhseets with decanters are more focused on finding ways to reduce energy consumption by introducing additional separators, a combination of several methods (extractive and heteroazeotropic complex columns with external decanters. The task of synthesizing all possible separation flowsheets is not considered in these works. In this paper, a complete set of flowsheets of different structures based on the combination of distillation and phase separation processes, including the use of columns with an external decanter, is proposed for water - butyl acetate - methanol and methanol - heptane-water ternary mixtures separation. Aspen Plus and NRTL model were used for mathematical modelling of phase equilibrium (the relative error of describing liquid-vapor and liquid-liquid equilibrium is less than 5%) was chosen as a method of research. Operating parameters for distillation columns (the number of theoretical plates, feed plate, reflux ratio) and the total energy consumption were obtained for each case. The necessity of using a double feed-plate column for separating of propanol-1 - water - butanol-1 and ethyl acetate - water - butyl acetate ternary systems was explained by the presence of extractive effect. Analytical review of modern publications and results of own research allowed to formulate a number of recommendations for the synthesis of energy effective flowsheets based on a combination of distillation and phase separation processes.