Design Of Separation Systems Research Articles

A novel reactive-extractive distillation process for separation of water/methanol/tetrahydrofuran mixtures

The design of separation systems for the purification of azeotropic mixtures is of great importance in the chemical industries from economic and environmental points of view. Two novel reactive-extractive distillation (RED) processes, new design (I) and new design (II), were proposed for separating the azeotropic mixture of water/methanol/tetrahydrofuran (THF). These processes were compared to a conventional extractive distillation (ED) process. New design (I) employs dimethyl sulfoxide as a solvent, while new design (II) utilizes ethylene glycol. Ethylene oxide was introduced to the first column in both designs, enabling the in-situ production of ethylene glycol, a valuable byproduct. This is a novel solution to separate water from the azeotropic mixture by reaction between ethylene oxide and water. Aspen Plus software was used to simulate and design the processes. Both suggested designs were compared economically with the base design which is an ED process. According to the results, the new design (I) is more cost-effective and environmentally friendly alternative to the base design and the new design (II). It has a lower total capital cost and produces less carbon dioxide. Additionally, it generates a valuable by-product, ethylene glycol, which can be sold for substantial revenue. As a result, the new design (I) is the preferred choice for replacing the conventional extractive distillation method.

Dry particle size separation using electrostatic traveling wave methods

Electrostatic traveling wave (ETW) methods have grown in popularity as a method to manipulate and separate fine particles. This is of interest to mineral processing and In-situ Space Resource Utilization. Here, we demonstrate that ETW can be used to separate particles by size. First, our numerical calculation and simulation results show the competing effect of DEP and Coulomb force on particle motion direction, which depends on the frequency, particle size and charge. Then we define the “crossover frequency” allowing prediction of operating parameters to separate particles. At the “crossover frequency” – a particle is equally likely to move forward or backward. The crossover frequency decreases as particle size increases, and the proportion of particles moving backward increases as frequency increases. Four size groups of ballotini particles (glass) were transported and collected at different wave field frequencies. Finally, we have demonstrated experimentally the separation of particles between 30–50 µm and 75–110 µm. Simulation and experiment results revealed the effects of frequency, particle size and charge on particle motions. And the model can be used to guide the design of separation systems.

Stage Separation System Design and Dynamic Analysis of Isro Launch Vehicles

Stage separation system design and dynamic analysis is an integral part of the design and development of any multistage launch vehicles. Lower stage separation especially, strapon separation qttracts specific attention if the separation occurs in the dense atmospheric region as aerodynamics plays a major role in design of separation system. FLSC is used to seyere the stages and spring thrusters or side rockets are used to provide required jettisoning velocity depending on the stage inert mass. In the booster stage separation, FLSC based severing together with retro-rockets or VIS separation systems are used to provide separation velocity. In VIS the continuing stage jet impingement force is used to provide required jettisoning velocity for the spent body. In heat shield separation, the impulse generated by Zip cord mechanism excites the rigid body and flexible modes of the heat shield. By superimposing flexible response over the rigid body motion dynamic analysis were carried out. The upper stages and spacecraft separation systims use clamp band joints with pyro assisted release mechanisms together with spring thrusters as jettisoning devices. Spring thrusters were used for spacecraft separation due to the requirement of low shock level and contamination free environment. In this paper, an attempt is made to expLain the experiences gained over the design, development, 6-D dynamic simulation studies and the improvements carried out for the four-generation Indian Launch Vehicles development programme namely SLV, ASLV, PSLV and GSLV in the last two decades.

Enabling SAT single pilot operations: tactical separation system design advancements in the COAST project

PurposeThis paper aims to describe the advancements of the activities that have been carried out, in the Cost-Optimized Avionics SysTem (COAST) project, to complete the design and in-flight demonstration of the Tactical Separation System (TSS), which is an automatic support system to the pilot’s decision-making, onboard on small air transport (SAT) vehicles under single pilot operations, in the separation management.Design/methodology/approachIn the framework of the Clean Sky 2 funded project COAST, some enabling technologies for single pilot operations in the EASA CS-23 category vehicles are designed and demonstrated in flight. Among the relevant flight management technologies addressed in the project, the specific one devoted to the real-time support to pilot’s decision-making in maintaining the vehicle self-separation is the TSS, designed by the Italian Aerospace Research Centre.FindingsThe TSS design started in the year 2016 and has been completed in the year 2021 after successful in-flight demonstration in the dedicated flight test campaign. The system has been validated by means of several simulation campaigns and finally demonstrated its effectiveness in providing its intended functionalities (situational awareness, conflict detection, conflict resolution) to the pilot in real flight trials, involving the presence of real conflicting aircraft.Originality/valueThe TSS contributes enabling the implementation of single pilot operations in CS-23 category vehicles, thanks to the possibility to support the pilot with provision of consolidated traffic picture, detection of conflicting surrounding traffic and suggestion of suitable conflict resolution manoeuvre real-time during the flight, through dedicated human–machine interface designed on purpose. The TSS supports the new separation modes that are envisaged in the future SESAR ATM target concept, with particular reference to the possible delegation of the separation responsibility to the pilot.

Improved design of separation system for the recovery of benzene and isopropanol from wastewater

In order to recover valuable benzene and isopropanol from wastewater, development of energy-efficient design flowsheet of this separation system is a relevant design problem in industry and worthy of investigation. The available separation methods in open literature were to either use a triple-column pressure swing distillation or by combining heterogeneous azeotropic distillation and pressure-swing distillation. Although the above two separation methods having the favorable feature of not introducing any foreign component into the system, the economics and energy consumption of the above separation design flowsheets can still be significantly improved. The purpose of this paper is to develop an improved design flowsheet for this separation task, not ever seen in open literature, making use of natural liquid–liquid splitting in a decanter and arranging the distillation sequence so that one of the preceding column to be designed as a stripper to preserve latent heat of this column’s top vapor stream. Further energy-saving schemes of this separation system were also thoroughly investigated. It is found that the economics of our proposed heat-integrated separation system can significantly cut 75.1% and 66.2% in total operating cost and total annual cost, respectively, as compared to that of the best separation system recently proposed in open literature.

Plantwide optimization coupled with column sequencing and stacking using a process simulator automation server

A method is proposed for plantwide process design and optimization that solves the column sequencing and stacking problems while also accounting for the tradeoff between reactor system design and separation system design. The plantwide process is represented by two flowsheets in a process simulator. One flowsheet represents the reactor network and the other flowsheet contains a single distillation column which is used to optimize each column in every sequence. When reactor design variables are specified, the reactor effluent flowrate and composition can be determined by simulating the reactor network flowsheet. Since the outlet from the reactor network is the feed to the separation system, the optimal separation system for this feed can then be designed. Finally, by looping over reactor design variables, a nearly-optimal plantwide process design can be determined. This permits plantwide optimization accounting for tradeoffs between the reactor section and separation section of a process while using rigorous modeling of both parts of the flowsheet. The rigorous models can still be constructed rapidly using commercial process simulation software. The method is illustrated with two case studies: the butane alkylation process and the cumene process.

Evolution of vortices in the wake of an ARJ21 airplane: Application of the lift-drag model

Wake separation is crucial to aircraft landing safety and is an important factor in airport operational efficiency. The near-ground evolution characteristics of wake vortices form the foundation of the wake separation system design. In this study, we analysed the near-ground evolution of vortices in the wake of a domestic aircraft ARJ21 initialised by the lift-drag model using large eddy simulations based on an adaptive mesh. Evolution of wake vortices formed by the main wing, flap and horizontal tail was discussed in detail. The horizontal tail vortices are the weakest and dissipate rapidly, whereas the flap vortices are the strongest and induce the tip vortex to merge with them. The horizontal tail and flap of an ARJ21 do not significantly influence the circulation evolution, height change and movement trajectory of the wake vortices. The far-field evolution of wake vortices can therefore be analysed using the conventional wake vortex model.

Membrane Flash Index: Powerful and Perspicuous Help for Efficient Separation System Design.

There are different factors and indices to characterize the performance of a pervaporation membrane, but none of them gives information about their capabilities in the area of liquid separation compared to the most convenient alternative, which is distillation. Membrane flash index (MFLI) can be considered the first and only one that shows if the membrane is more efficient or not than distillation and quantifies this feature too. Therefore, the MFLI helps select the best separation alternative in the case of process design. In this study, the evaluation and capabilities of membrane flash index are comprehensively investigated in the cases of six aqueous mixtures: methyl alcohol–water, ethyl alcohol–water, isobutyl alcohol–water, tetrahydrofuran–water, N-butyl alcohol–water, and isopropanol–water. It must be concluded that the separation capacity of organophilic type membranes is remarkably lower than hydrophilic membranes in all cases of separation. The study of the MFLI is extended with the consideration of other binary interaction parameters like separation factor, permeation flux, selectivity, and pervaporation separation index (PSI) in order to find a descriptive relationship between them. For the same membrane material type, descriptive function can be determined between feed concentration and MFLI and PSI and separation factor, which can be used to calculate each other’s value. On the basis of the indices and especially the MFLI, a significant help can be given to the process design engineer to select the right liquid separation alternative and, in the case of pervaporation, find the most appropriate membrane.

Electrokinetic assessment of RNase A species and innovative PEG-grafted agarose-based resins used in downstream processing of PEGylated proteins

Detailed study of the governing mechanisms of hydrophobic interaction chromatography in protein purification plays a key role in the design of separation systems. In our previous work, an innovative covalently bonded poly(ethylene glycol) (PEG) to Sepharose® 6B resin was developed. It could successfully separate PEGylated ribonuclease A (RNase A) species in a single chromatographic step (Hernández-Martínez and Aguilar, 2014), however, its electrokinetic profile has not been evaluated. The aim of this work was to study electrokinetics of RNase A species, unactivated, activated and activated-PEGylated Sepharose® 6B resins, and 5–40 kDa PEGylated resins. Electric potential, mobility and conductivity of resins was determined in presence of 0.025 M potassium phosphate buffer pH 7.0 supplemented with ammonium sulfate. Scanning electron microscopy and infrared spectroscopy techniques were used to characterize the resins. All protein and resins surfaces were negatively charged at pH 7.0 and ζ potential was dependent on electrolyte ion concentration. Variation in PEG molecular weight caused variation in ζ potential at low electrolyte concentrations. Morphology of resins did not change after resin PEGylation, however, size of particles ranged between 8–55 μm. These results contribute to electrokinetics understanding of RNase A and PEG-grafted resins, providing electric characterization of their surfaces, which is essential in the design, improvement and problem-solving in chromatographic methods for PEGylated species purification.

Isobaric Vapour–Liquid Equilibrium Data Measurement for a Binary System of Green Solvent 2-Methyltetrahydrofuran and Acetic acid at 101.3 kPa

Green solvents are eco-friendly solvents that can play significant role in the reduction in health hazard and safety issues caused by classical solvents. The use of green solvents can be supported and enhanced by providing the data banks of these solvents, particularly vapour–liquid equilibrium (VLE) data that are required for the design of separation systems. A dynamic VLE still based on the Raal modification of Yerazunis et al. (1964) apparatus was employed in the measurement of isobaric VLE data. The VLE still was maintained at 101.3 kPa pressure. The thermodynamic consistency of the measured VLE data was confirmed by Herington’s area test and Van Ness’s point-to-point test. The correlation of VLE data was established by excess Gibbs energy models NRTL, Wilson and UNIQUAC and the result showed that all three models were in good agreement with the experimental data. The absolute average deviation in temperature was 0.3953 K, 0.3823 K, 0.3977 K and the absolute average deviation in vapour-phase composition was 0.0053, 0.0052, 0.0053 for NRTL, Wilson and UNIQUAC models, respectively. The relative volatility chart of 2-MeTHF/Acetic acid versus 2-MeTHF liquid mole fraction showing $$\pm \,5\%$$ deviation of experimental data from Wilson model data was also depicted. The comparison of the experimental VLE data with the data predicted by UNIFAC and modified UNIFAC Dortmund methods was made. The VLE data were generated through binary interaction parameters from Aspen Hysys for Wilson, NRTL and UNIQUAC models and compared with the experimental data.

Modeling and testing of a tube-in-tube separation mechanism of bodies in space

A tube-in-tube concept for separation of bodies in space was investigated theoretically and experimentally. The separation system is based on generation of high pressure gas by combustion of solid propellant and restricting the expansion of the gas only by ejecting the two bodies in opposite directions, in such a fashion that maximizes generated impulse. An interior ballistics model was developed in order to investigate the potential benefits of the separation system for a large range of space body masses and for different design parameters such as geometry and propellant. The model takes into account solid propellant combustion, heat losses, and gas phase chemical reactions. The model shows that for large bodies (above 100kg) and typical separation velocities of 5m/s, the proposed separation mechanism may be characterized by a specific impulse of 25,000s, two order of magnitude larger than that of conventional solid rockets. It means that the proposed separation system requires only 1% of the propellant mass that would be needed for a conventional rocket for the same mission. Since many existing launch vehicles obtain such separation velocities by using conventional solid rocket motors (retro-rockets), the implementation of the new separation system design can reduce dramatically the mass of the separation system and increase safety. A dedicated experimental setup was built in order to demonstrate the concept and validate the model. The experimental results revealed specific impulse values of up to 27,000s and showed good correspondence with the model.

Outer approximation algorithm with physical domain reduction for computer‐aided molecular and separation process design

Integrated approaches to the design of separation systems based on computer‐aided molecular and process design (CAMPD) can yield an optimal solvent structure and process conditions. The underlying design problem, however, is a challenging mixed integer nonlinear problem, prone to convergence failure as a result of the strong and nonlinear interactions between solvent and process. To facilitate the solution of this problem, a modified outer‐approximation (OA) algorithm is proposed. Tests that remove infeasible regions from both the process and molecular domains are embedded within the OA framework. Four tests are developed to remove subdomains where constraints on phase behavior that are implicit in process models or explicit process (design) constraints are violated. The algorithm is applied to three case studies relating to the separation of methane and carbon dioxide at high pressure. The process model is highly nonlinear, and includes mass and energy balances as well as phase equilibrium relations and physical property models based on a group‐contribution version of the statistical associating fluid theory (SAFT‐γ Mie) and on the GC+ group contribution method for some pure component properties. A fully automated implementation of the proposed approach is found to converge successfully to a local solution in 30 problem instances. The results highlight the extent to which optimal solvent and process conditions are interrelated and dependent on process specifications and constraints. The robustness of the CAMPD algorithm makes it possible to adopt higher‐fidelity nonlinear models in molecular and process design. © 2016 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 62: 3484–3504, 2016

Inhibition of Metal Hydrogenation Catalysts by Biogenic Impurities

We show that supported Ni, Pt, and Pd catalysts used for liquid phase hydrogenation are inhibited by the biogenic impurities present in biologically-derived feedstocks used to produce high-value chemicals. The effects of thiamine HCl, cysteine, methionine, biotin, tryptophan, niacin, threonine, and p-aminobenzoic acid were elucidated by collecting adsorption isotherms of these species and by quantifying their influence on the rate of cyclohexene hydrogenation at 323 K. Inhibition increases in the order of Pd < Pt < Ni and generally correlates with the binding energies of sulfur and nitrogen. The equilibrium constants reported here for adsorption of these species on Ni, Pt, and Pd can facilitate the design of separation systems and new catalysts used for upgrading biologically-produced platform molecules.

Dynamics Analysis of the Spatial Catapult Separation Problem

This paper analyzed the spatial catapult dynamics of spatial catapult on-orbit separation problem equipped with a separate rail, providing the basis for separation of ground testing and separation system design. under the premise of separation requirements as well as the arbitrariness of locations of the spring and rail, By using newtonian dynamics, as well as momentum theorem and angular momentum theorem, the dynamic model of the separating motion was formulated in translational inertial reference frame .Solution examples with different initial conditions were offered ,and the accuracy of the model is verified via the solution of numerical simulation.

Design of Separation System for Used Oil Filter

Design of Separation System for Used Oil Filter

Hydrogen Isotope Separation Factor Measurement for Single Stage Hydrogen Separators and Parameters for a Large-Scale Separation System

A Concept design for large-scale hydrogen ISS based on a single Pd alloy membrane separator cascade has been presented. Separators to investigate the feasibility of the Pd membrane separator cascade concept have been designed and the separation performance of the separators is given. Results show that the separation factors, which are between 1.4 and 1.8 at the operation temperature, are large enough for a practical separation system design. Estimation results indicate that a 2.0m2 Pd membrane is needed for a 20mol/h and 12 stages batch ISS, and an approximately 50m2 Pd membrane is needed for a 200mol/h and 26 stages ISS. It is clear that the separator cascade concept is both reasonable and practicable for large-scale hydrogen isotope separation.

Novel separation system design using “moving triangles”

Shortcut design techniques have been employed in the initial design of traditional distillation systems. Current techniques are not useful in the design of novel or complex configurations however. We will show that by using column profile mapping “moving triangles” to model the behaviour of column sections (CS), any distillation configuration, no matter how complex, can be modelled and its behaviour more thoroughly understood. As an example, a thermally coupled column will be modelled using column profile maps. It is suggested that by gaining an understanding of the behaviour of the configuration quickly and easily, using column profile maps, time and money can be saved by avoiding poor initial decisions and designs.

Computing Homogeneous Azeotropes Using Interval Analysis

Determining the existence of homogeneous azeotropes, together with their composition and temperature, is important from both theoretical and practical standpoints in the analysis of phase behavior and in the synthesis and design of separation systems employing distillation. We describe a new method that reliably locates any and all homogeneous azeotropes for multicomponent mixtures, and also verifies the nonexistence of homogeneous azeotropes if none are present. The method is based on interval analysis, and provides a mathematical and computational guarantee that all azeotropes are located. The technique is general purpose and can be applied in connection with any thermodynamic model describing vapor-liquid equilibrium. An example using a five-component mixture modeled with the NRTL equation is presented.

Modular representation synthesis framework for homogeneous azeotropic separation

AbstractThe synthesis and design of separation systems for nonideal azeotropic mixtures traditionally utilize graphical methods, focusing on separation feasibility within a sequential design framework. Once promising systems have been identified, sequencing and design are optimized in a second stage, limited by the separation feasibility region defined in the first stage. A generalized modular representation proposed for the synthesis of nonideal separations can simultaneously explore entrainer and sequencing alternatives. A multipurpose mass/heat exchange module, introduced in earlier work, is employed to investigate separation units and structures as mass‐ and heat‐exchange possibilities. Process units, separation sequences, and entrainers that aid the separation are examined within one separation problem rather than in a sequential manner. Promising separation schemes can be further considered for detailed design optimization.

Reliable computation of homogeneous azeotropes

AbstractIt is important to determine the existence and composition of homogeneous azeotropes in the analysis of phase behavior and in the synthesis and design of separation systems, from both theoretical and practical standpoints. A new method for reliably locating any and all homogeneous azeotropes for multicomponent mixtures is presented. The method also verifies the nonexistence of homogeneous azeotropes if none are present. The method is based on interval analysis, in particular an interval‐Newton/generalized‐bisection‐algorithm providing a mathematical and computational guarantee that all azeotropes are located. This general‐purpose technique can be applied in connection with any thermodynamic models. The technique is illustrated in several example problems using the Wilson, NRTL, and UNIQUAC activity‐coeficient models.