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    Hierarchical optimal control of a binary distillation column

    , Article Optimal Control Applications and Methods ; 2018 ; 01432087 (ISSN) Ramezani, M. H ; Sadati, N ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Abstract
    This paper presents a two-level optimal control for the binary distillation column. From the control point of view, the binary distillation column is a high-order system consisting of several interconnected subsystems (trays) that aim to maximize output purity. Controlling the system in a hierarchical manner not only decreases complexity and solution time but also can improve the control structure's reliability. In this study, the distillation column is decomposed into NT second-order subsystems, each representing one stage (one tray). Accordingly, the cost function is decomposed, and thus, the overall problem is converted into NT lower-order subproblems where each tray has its own... 

    Simulation and performance improvement of cryogenic distillation column, using enhanced predictive Peng–Robinson equation of state

    , Article Fluid Phase Equilibria ; Volume 489 , 2019 , Pages 117-130 ; 03783812 (ISSN) Ardeshir Larijani, M ; Bayat, M ; Afshin, H ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    In this study, a cryogenic distillation column has been designed and simulated via a computer code based on the theta method of convergence. The required thermodynamic properties are determined from the enhanced predictive Peng-Robinson (E-PPR 78) equation of state which has a good accuracy in predicting the corresponding thermodynamic properties of natural gas components. The combined code of distillation column/equation of state has been verified with that of another study. In the present study, the results are achieved by the constant molar over-flow and inclusion of energy equations assumptions. In order to have more accuracy in the results, the energy equations were considered in the... 

    Steady-State Operability Analysis of Nonlinear Plants Using Output Controllability Index

    , M.Sc. Thesis Sharif University of Technology Moradpanah, Maryam (Author) ; Pishvaie, Mahmoud Reza (Supervisor)
    Abstract
    Selecting an appropriate control structure is an important subject in the design of control systems. Distillation column is one of the most popular and widely used unit operations in industry which complete understanding of its operability and controllability is one of the most important issues in the process control engineering. The present work studies the method of Output Controllability Index for nonlinear systems and compares it with Relative Gain Array and Condition Number. By using this index, the extent of intrinsic controllability of a process can be identified quantitatively in the absence of any controller. Also, the controllability of the process can be stated numerically or... 

    Impact of Internally Heat-Integrated Distillation Column Configuration on Energy Saving

    , M.Sc. Thesis Sharif University of Technology Saber, Mohammad (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Rashtchian, Davood (Supervisor)
    Abstract
    Distillation is the most widely-used but the most energy-consuming separation process in the chemical industry. The thermal energy added at the reboiler is used to evaporate a liquid mixture and is wasted when liquefying the vapor flow at the condenser to obtain a reflux liquid flow. However, the thermal energy recovered at the condenser cannot be used to heat other flows in the same distillation column since its temperature is lower than the other stages. To improve the low energy efficiency of distillation, various new ideas have been proposed in the literature. One of them is the internally heat-integrated distillation column (HIDiC). In a conventional distillation column, the temperature... 

    On-line nonlinear dynamic data reconciliation using Extended Kalman Filtering: Application to a distillation column and a CSTR

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 28, Issue 3 , 2009 , Pages 1-14 ; 10219986 (ISSN) Farzi, A ; Mehrabani Zeinabad, A ; Bozorgmehry Boozarjomehry,R ; Sharif University of Technology
    Abstract
    Extended Kalman Filtering (EKF) is a nonlinear dynamic data reconciliation (NDDR) method. One of its main advantages is its suitability for on-line applications. This paper presents an on-line NDDR method using EKF. It is implemented for two case studies, temperature measurements of a distillation column and concentration measurements of a CSTR. In each time step, random numbers with zero mean and specified variance were added to simulated results by a random number generator. The generated data are transferred on-line to a developed data reconciliation software. The software performs NDDR on received data using EKF method. Comparison of data reconciliation results with simulated... 

    Simulation and control of an aromatic distillation column

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 26, Issue 2 , 2007 , Pages 97-108 ; 10219986 (ISSN) Valadkhani, A ; Shahrokhi, M ; Sharif University of Technology
    2007
    Abstract
    In general, the objective of distillation control is to maintain the desired products quality. In this paper, the performances of different one point control strategies for an aromatic distillation column have been compared through dynamic simulation. These methods are: a) Composition control using measured composition directly. This method sufferes from large sampling delay of measuring devices, b) Composition control by controlling the temperature of a specific tray. In this strategy, the composition-temperature relationship is used to find the temperature setpoint corresponding to the desired composition. Since composition-temperature relation depends on feed condition, an artificial... 

    Evolutionary design of optimum distillation column sequence

    , Article Canadian Journal of Chemical Engineering ; Volume 90, Issue 4 , 2012 , Pages 956-972 ; 00084034 (ISSN) Boozarjomehry, R. B ; Laleh, A. P ; Svrcek, W. Y ; Sharif University of Technology
    2012
    Abstract
    Synthesis of the optimum distillation column sequence (DCS), which incorporates a huge search space composed of both conventional and complex arrangements, is a highly complicated combinatorial problem in the field of chemical process design and optimisation. In this study, a novel procedure for the synthesis of optimum DCS proposed by Boozarjomehry et al. [Boozarjomehry et al., Can. J. Chem. Eng. 87, 477-492 (2009)] is expanded to include the complex distillation arrangements. The method is based on evolutionary algorithms, and the total annual cost (TAC) is the main criterion used to screen alternatives. Efficient procedure has been proposed for encoding mechanism to include and classify... 

    Automatic design of conventional distillation column sequence by genetic algorithm

    , Article Canadian Journal of Chemical Engineering ; Volume 87, Issue 3 , 2009 , Pages 477-492 ; 00084034 (ISSN) Bozorgmehry Boozarjomehry, R ; Pourahmadi Laleh, A ; Svrcek, W. Y ; Sharif University of Technology
    2009
    Abstract
    Synthesis of the optimum conventional (with non-sharp separations) distillation column sequence (DCS) is a challenging problem, in the field of chemical process design and optimization, due to its huge search space and combinatorial nature. In this paper, a novel procedure for the synthesis of optimum Conventional Distillation Column Sequence is proposed. The proposed method is based on evolutionary algorithms. The main criterion used to screen alternative DCS's is the Total Annual Cost (TAC). In order to estimate the TAC of each DCS alternative all columns that exist in the DCS are designed using short-cut methods. The performance of the proposed method and other alternatives are compared... 

    LPG mass separation by vortex tube cascade and its economics

    , Article Applied Thermal Engineering ; Volume 148 , 2019 , Pages 1139-1147 ; 13594311 (ISSN) Majidi, D ; Alighardashi, H ; Farhadi, F ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    In the present experimental study, the effect of operating parameters such as inlet and outlet pressure as well as inlet temperature on the mass separation capability of vortex tubes (VTs) for a gas mixture is investigated. Specifically, concentrating heavier components of a gas mixture in the hot outlet stream is considered. Proposing a semi-empirical index from the experimental study, the simulation of different arrangements of VTs, and the effect of recycling a portion of the hot outlet stream on its mass separation performance are investigated. Moreover, the proposed separation method by VTs is economically compared with commonly used methods by distillation columns and two-phase... 

    Control of High Purity Distillation Columns

    , M.Sc. Thesis Sharif University of Technology Roodpeyma, Maedeh (Author) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    Selection of the most appropriate control configuration for two point control strategy in a distillation column is a challenging problem. In the present work, three control configurations namely , and , have been employed to control a high purity distillation column separating the binary mixture of Benzene-Toluene. A simple linear model for the process has been derived via a system identification technique. The uncertainty and performance weights have been defined and have been utilized to design a robust controller based on the μ-synthesis approach. The genetic algorithm is employed and the peak value of μ is minimized in order to obtain appropriate PI controller parameters for each... 

    Technical and Economical Feasibility Study of Applying Heat Pump Systems to Provide Utilities for Oil & Gas Industries

    , M.Sc. Thesis Sharif University of Technology Hamidzadeh, Zeinab (Author) ; Sattari, Sorena (Supervisor) ; Amidpour, Majid (Supervisor)
    Abstract
    Distillation is the most applied unit in the separation processess of the oil and gas industries. Because the distillation process requires energy in the form of the utilities, integration of heat pump systems in the distillation process as an application of these systems is considered in this research. A new and effective methodology of proper integrating of heat pump and distillation columns has been proposed by collecting thermodynamic and thermoeconomic tools. Then, this procedure has been applied on the ethane recovery and NGL fractionation units of 4 & 5 phases of the south pars field. The exergy analysis of the distillation columns is the first step of this methodology as the... 

    Rigorous Synthesis of Optimal Heat Integrated Complex Column Sequences Using Genetic Algorithm

    , M.Sc. Thesis Sharif University of Technology Baroughi, Amir Hossein (Author) ; Bozorgmehri, Ramin (Supervisor) ; Farhadi, Fathollah (Supervisor)
    Abstract
    Finding the optimal heat integrated distillation column sequence is an utmost important optimization problem in process engineering. The frequently used approach in this area is to obtain a suitable sequencing candidate and then accomplish the heat integration based on the application of Pinch technology to finalize the design. This approach reduces the problem complexity at the expense of not necessarily reaching the best possible result. This work follows a genetic super structure approach to systematic and rigorous synthesis of optimal multi-component distillation sequences (including simple and thermally coupled complex columns) and simultaneously heat exchanger networks by using a... 

    Shortcut design of reactive distillation columns

    , Article Chemical Engineering Science ; Volume 71 , 2012 , Pages 166-177 ; 00092509 (ISSN) Avami, A ; Marquardt, W ; Saboohi, Y ; Kraemer, K ; Sharif University of Technology
    Abstract
    Shortcut design methods can be valuable tools for rapid screening of different separation process alternatives to assess feasibility and determine minimum energy demand. This work presents a variant of the feed angle method (Kraemer et al., 2011), which applies to single- and double-feed reactive distillation columns. The proposed method relies on pinch point analysis and determines the minimum energy demand from the calculation of a tray at the feed pinch. It is fully algorithmic and insensitive to impurities in product specifications. Its validity and performance is illustrated by a variety of case studies covering multi-component and multi-reaction systems, mixtures with potential... 

    An applicable method for efficiency estimation of operating tray distillation columns and its comparison with the methods utilized in HYSYS and Aspen Plus

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 51, Issue 10 , October , 2015 , Pages 1393-1402 ; 09477411 (ISSN) Sadeghifar, H ; Sharif University of Technology
    Springer Verlag  2015
    Abstract
    Developing general methods that rely on column data for the efficiency estimation of operating (existing) distillation columns has been overlooked in the literature. Most of the available methods are based on empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods may not be sufficiently accurate when applied to industrial columns. In this paper, an applicable and accurate method was developed for the efficiency estimation of distillation columns filled with trays. This method can calculate efficiency as well as mass and heat transfer coefficients without using any empirical mass transfer or hydraulic correlations and without the need to... 

    Economic optimization of heat pump-assisted distillation columns inmethanol-water separation

    , Article Energy ; Volume 80 , 2015 , Pages 496-508 ; 03605442 (ISSN) Shahandeh, H ; Jafari, M ; Kasiri, N ; Ivakpour, J ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    Finding efficient alternative to CDiC (Conventional Distillation Column) for methanol-water separation has been an attractive field of study in literature. In this work, five heat pump-assisted schemes are proposed and compared to each other to find the optimal one; (1) VRC (Vapor Recompression Column), (2) external HIDiC (Heat-Integrated Distillation Column), (3) intensified HIDiC with feed preheater, (4) double compressor intensified HIDiC-1, and (5) double compressor intensified HIDiC-2. GA (Genetic Algorithm) is then implemented for optimization of the schemes when TAC (Total Annual Cost) is its objective function. During optimization, two new variables are added for using only... 

    Comparison of Dynamic and Static Performances of a Quaternary Distillation Sequence

    , Ph.D. Dissertation Sharif University of Technology Baghmisheh, Gholmarez (Author) ; Shahrokhi, Mohammad (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
    Abstract
    In this work steady state and dynamic performances of quaternary distillation column sequences designed based on steady state and dynamic cost functions have been investigated. To quantify the dynamic performance, product loss due to disturbances has been considered in the objective function. In addition, variations of operating costs such as utilities have been considered in the objective function. To separate a quaternary mixture into four products, twenty two configurations have been used. It has been observed that the feed composition, disturbance frequency and magnitude affect the dynamic behavior strongly. To decrease the optimization computational load, a scheme that provides a... 

    Design and Performance Improvement of Distillation Column of Helium Purification Cycle

    , M.Sc. Thesis Sharif University of Technology Bayat, Mohammad (Author) ; Afshin, Hossein (Supervisor)
    Abstract
    Due to its unique properties, helium has extensive applications in various fields such as medicine, life sciences, electronic industries, welding, meteorology, and the industries which require low-temperature cooling. Also, designing the cryogenic distillation columns is one of the complex aspects of these plants. In the present study, the distillation column of a helium extraction plant from natural gas has been simulated by means of theta method of convergence. The required thermodynamic properties were determined from the Enhanced Predictive Peng-Robinson (E-PPR 78) equation of state, which has high accuracy in predicting the thermodynamic properties of natural gas componens. The... 

    Design and Optimization of Helium Recovery Process from Natural Gas

    , M.Sc. Thesis Sharif University of Technology Azimi, Sajad (Author) ; Afshin, Hossein (Supervisor) ; Farhanieh, Bijan (Co-Supervisor)
    Abstract
    Helium is a valuable substance that is widely used in industry and medicine because of its unique properties. Due to the increasing demand for helium in the global market, several helium extraction units have been launched in the world in recent years; Nevertheless, there is still a significant gap between projected global helium production capacity and demand. Today, natural gas is known as the main source of helium on the earth. The method of industrial extraction of helium from natural gas is cryogenic. Due to the low temperature of this process, relatively high power consumption is used to extract helium from natural gas. Therefore, the optimization of this process is of great... 

    Design and Optimization of Helium Extraction and Liquefaction Cycle from Natural Gas by Direct Method

    , Ph.D. Dissertation Sharif University of Technology Ardeshir Larijani, Morteza (Author) ; Afshin, Hossein (Supervisor)
    Abstract
    Helium is known as a strategic material due to its unique properties and applications in the development of advanced industries. Currently, natural gas is the only source from which helium can be produced economically. The United States, Qatar, Algeria, and Russia have the largest share of helium production, respectively. In this research, the process of helium extraction from natural gas and its liquefaction, independent of LNG production based on helium in South Pars gas of Iran, which is the largest helium reservoir in the world, were designed and simulated.In the helium liquefaction section, the speed and accuracy of the process simulation were improved by developing a home code based on... 

    A new and applicable method to calculate mass and heat transfer coefficients and efficiency of industrial distillation columns containing structured packings

    , Article Energy ; Volume 36, Issue 3 , 2011 , Pages 1415-1423 ; 03605442 (ISSN) Sadeghifar, H ; Safe Kordi, A. A ; Sharif University of Technology
    2011
    Abstract
    Most of the methods developed for efficiency estimation of distillation columns were based on the empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods cannot estimate efficiency of industrial columns with sufficient accuracy. In this paper, a new and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of distillation columns containing structured packings. This method has potential advantages; e.g., it can calculate efficiency without using any empirical mass transfer and hydraulic correlations and models, and without the need to estimate the operational and hydraulic parameters of column....