Operation Of Batch Distillation Research Articles

Utilization of waste transformer oil as a fuel in diesel engine

The growing price of fossil oils, the gradual decline of petroleum supplies and the unsustainable emissions of motor vehicles led researchers to look for substitute fuel, such as waste lubricant oil and waste transformation oil (WTO). In power transformers, welding transformers, and electromotive systems, a significant volume of transformer oil is used as a coolant. The electrical transformer is an integral part of electrical power transmission and distribution equipment used in smaller, intermediate and larger electrical distribution stations. The efficiency and lifespan of an electrical transformer depend upon the transformer’s efficient cooling and insulation. During the working of a transformer, transformer oil is exposed to electrical and thermal stress due to which it started to degrade after some time. Thus a huge amount of degraded transformer oil is rejected as waste. The paper details the utility of waste transformer oil by using simple batch distillation operation at atmospheric pressure by analyzing the physiochemical properties of the product. The treated transformer oil is further tested in the diesel engine to examine fuel efficiency. Diesel engine runs were performed with various combinations of blends consists of diesel fuel and treated transformer oil. Results reveal that brake thermal efficiency of the blends found at 10%, 20%, 30% and 40% is 28.19%, 27.52% 26.21% and 25.98% respectively. The brake specific fuel consumption of blends at 10%, 20%, 30% and 40% is 0.29 KJ/Kwhr, 0.30 KJ/Kwhr 0.31 KJ/Kwhr and 0.315 KJ/Kwhr respectively.

Economic feasibility of a novel energy efficient middle vessel batch distillation to reduce energy use

It has long been recognized that the highly irreversible operation of batch distillation involves more wastage of energy compared to continuous flow distillation. For boosting its energy efficiency, the middle vessel batch distillation (MVBD) column has been invented. In this paper, a rigorous model for an MVBD process for the separation of a ternary hydrocarbon system is developed to simulate its transient behavior. In order to obtain the products at their maximum achievable purities, we device the two operating policies for the representative configuration.This contribution introduces a heat pumping system in the MVBD aiming to further improve its energetic and economic potentials. This novel heat integration technique is operated with a variable speed compressor for pressurizing the overhead vapor before thermally coupling it with the reboiler liquid. Interestingly, along with the compression ratio (CR), the other two manipulated variables are the inflow rate of overhead vapor to the compressor and that of an external medium (here, steam) that provides makeup heat to the reboiler. The operation of this adaptive heat pump assisted column originally involves the simultaneous adaptation of two variables throughout the entire batch processing. The simulation results show that a cost savings predicted in the heat integrated MVBD scheme can be achieved along with a substantial reduction in energy consumption.

Study of Multi-Component Batch Distillation Calculation with Parameters Estimated Using Simple Distillation

The compositions and the physical properties of mixtures are required to simulate multi-component batch distillation operations. In this study, temperature and accumulated distillate are measured as a function of time by use of a simple distillation apparatus. Initial compositions and physical parameters are estimated from this measurement data by a dynamic mathematical model, to examine the extent to which batch distillation operations can be predicted. For an ideal and a non-ideal solution system, the following three types of value estimation are examined: (I) compositions only, (II) parameters of one component, and (III) compositions and parameters of one component. The compositions could be estimated with sufficient accuracy. As for the physical properties, after devising a method for reducing the number of parameters, it is found that a batch distillation operation can be industrially designed from the estimated results.

Multi-objective optimisation of batch separation processes

This paper considers for the first time the simultaneous multi-objective optimisation of design and operation of batch distillation as well as of batch hybrid distillation/pervaporation processes. The overall problem is formulated as a multi-objective mixed integer dynamic optimisation (MO-MIDO) problem. The optimisation strategy comprises of different ranking procedures that allow the determination of the Pareto optimal set. A case study for the separation of a homogeneous tangent-pinch (acetone–water) mixture is presented for a dual-criteria optimisation case of minimising capital investment while at the same time minimising the energy consumption rate during the batch. It is found that the proposed distance ranking procedure yields the best Pareto optimal set when compared to other non-dominated sorting procedures. Furthermore, the distance ranking procedure was found to be further improved when used with an elitism operator.

Optimisation of design and operation parameters for ternary batch distillation with fixed product demand

PurposeTo determine optimum design and operation parameters for ternary batch distillation under fixed product demand.Design/methodology/approachIn this study, two different scenarios are considered. In the first scenario, the column specification (in terms of number of plates and vapour load) and product demand are given and the optimum operation policy is determined. In the second scenario, with a fixed batch time and product demand, the optimal design (in terms of number of plates and vapour load) and operation policy (in terms of reflux ratio profile) are determined. In both scenarios, maximisation of a profit function reflecting capital cost, operating cost and penalty due to under/over production and customer dissatisfaction is considered. A detailed dynamic model consisting of mass and energy balances with rigorous thermodynamic property calculation model is used. The optimisation problem is solved using modified simulated annealing algorithm.FindingsTwo ternary mixtures leading to easy and difficult separation were considered. The off‐cut production and recycling has been found to be more beneficial for difficult separation mixture than that for easy separation mixture. The net profit increases with over production more than under production of the products. This is because of the penalty imposed for customer dissatisfaction. It is better to over produce, as that will achieve the maximum profit and (at the same time) satisfy the customer. Finally, for a typical case study, the net profit with optimum design is found to be about 25 per cent more compared to the net profit obtained with fixed design.Originality/valueOptimal design and operation of multicomponent batch distillation has received limited attention in the past. Also, these studies were not geared for fixed product demand scenario. The optimisation problem formulation considered in the past, led to unlimited production of products (based on the assumption that all products produced are saleable) to maximise the profitability. Also, there were no penalties for over or under production of the desired products, production of off‐cuts and customer dissatisfaction due to not meeting the order (amount of products and delivery time, etc.). In this work, for the first time, these issues are addressed in the optimisation problem formulation.

Theoretical analysis and operating behaviour of a middle vessel batch distillation with cyclic operation

The present work deals with the cyclic operation of a middle vessel batch distillation (CMVBD). To provide an insight into this highly interesting distillation configuration, theoretical and experimental investigations have been carried out. After a theoretical system analysis, a process control strategy of industrial relevance is proposed. In the experimental part of this work, relevant tasks regarding the dynamic and steady-state behaviour have been considered. This includes the investigation of maximum product qualities and yields as well as the transient behaviour in response to setpoint changes and disturbances. Additionally, a mathematical model of a CMVBD is presented to describe the operating behaviour.

Cyclic total reflux batch distillation with two reflux drums

The present work proposes a novel cyclic total reflux (CTR) operation of batch distillation with two reflux drums working alternatively. A mathematical model is set up for the process. The computational comparison of the novel policy with the regular constant reflux and non-cyclic total reflux (NCTR) operations is also presented. The experimental runs of the new mode show that it can be operated and controlled more easily. The novel operation is significantly time saving compared to the mode of regular constant reflux theoretically and experimentally. The two reflux drum mode of CTR is also suitable for the separation of the mixture containing a large amount of light component.

Simultaneous optimal configuration, design and operation of batch distillation

AbstractA methodology for simultaneous determination of optimal batch distillation configuration, design and operation is presented. The configuration design methodology utilizes a mixed integer dynamic optimization (MIDO) formulation approach, where the optimal batch distillation system is obtained automatically, based on its maximum overall profitability for a given separation duty. Using rigorous models, the MIDO problem is solved using a practical stochastic solution approach of genetic algorithm and penalty function. The feasibility of this methodology is demonstrated for both binary and multicomponent separation scenarios. In the binary separation case study, the effect of feed composition for different binary mixtures on the optimal configurations, that is, regular vs. inverted columns, is investigated and discussed. The regular column was found to be more profitable for feeds with a high fraction of the light component, whereas the inverted column is optimal for heavier feeds. The optimality of a particular configuration over another is, however, case study specific, depending on, for example, how easy the mixture is to separate. In the multicomponent separation case study, the results obtained highlight the superiority of the multivessel configuration over the regular and inverted configurations. © 2005 American Institute of Chemical Engineers AIChE J, 2005

The effect of off-cut recycle on the optimum design and operation of binary batch distillation with fixed product demand

Off-cut production and recycling played an important role in efficient separation of binary and multicomponent mixtures using batch distillation. However, the research in this area is handful and all the investigations until to date were concerned with only operation optimisation in terms of minimisation of batch time or maximisation of productivity (amount of main products per unit time). No consideration was given to market demand of the products; therefore these operation policies would result in under and over production of the products leading to potential revenue losses. In this work, for the first time we considered both design (number of stages, vapour load) and operation (reflux ratio, batch time) optimisation for fixed market demand of the products while maximising a profit function reflecting product revenues, operating cost, storage cost and annualised capital cost. The effect of off-cut production and recycling on the design, operation and profitability are evaluated using an easy and a difficult binary separation problem and off-cut recycling is found to be more beneficial for difficult separation. Design and operation policies are also found to be different for different amount of off-cut. Finally, the storage cost can be a deciding factor for the production and recycling of off-cut.

Optimisation of design and operation policies of binary batch distillation with fixed product demand

Optimal design (vapour load, V and number of stages, N) and operation (reflux ratio, R and batch time, t b) of batch distillation have received significant attention in recent years. In these studies, it has been suggested that V should be set at some upper limit (thought to be optimum) and the optimisation task should be focused on finding the optimum values of N, R and t b, which would minimise the capital investment while maximising an economic objective function usually the profit ( P). The major drawback of such optimisation strategy is that there is no constraint on the amount of product (on specification) being produced ( N B = no. of batches in a given time) and the overall profit can only be maximised by producing unlimited amount of products. Unplanned and unlimited production of products are not sustainable and may lead to significant losses in the case of large inventory requirements of any excess products produced. In this work, for the first time, the optimal design and operation task for batch distillation is considered with due regards to the market demands (small to large number of batches) of the products being produced. An optimisation problem formulation is presented for the task which is different than those used in the past under unlimited product demand scenario. Simulated Annealing type algorithm is used for the solution of the optimisation problem. With several examples, it will be shown that fixing V a priori (say V < V opt) will not allow production of N B batches of products with any combination of ( N, R, t b) in a given production time. Also it will be shown that with V fixed at say V > V opt, P will always be < P max for any combination of ( N, R, t b). The comparisons between the results with and without fixing of V a priori show very clear improvement in the annual profit.

Simultaneous optimal design and operation of multivessel batch distillation

AbstractThe multivessel system is a novel batch distillation configuration that offers improved separation performance compared to the conventional single‐column batch rectifier. The optimal design of this system based on an economics performance index is solved for the first time here by adopting an evolutionary adaptive search technique. The utilization of an overall profitability index, and simultaneous consideration of key design and operation decision variables, allow the true optimum of the system to be obtained. The optimal system configuration is dependent on the separation duty and can contribute significantly to achieving a higher separation performance. The combined energy efficiency and production rate of the multivessel system is found to be greater than that of the regular column, and the benefit is more prominent when separating mixtures with more components. Further theoretical case studies are also presented to highlight the effect of feed composition, relative volatility, and product specification on the optimal column section configuration and feed distribution of the multivessel system.

Simultaneous optimal design and operation of multipurpose batch distillation columns

This work presents a robust method for the integrated design and operation of batch distillation whereby optimal column sizing, process flexibility and operating policies are obtained simultaneously based on the complex economic trade-offs between capital investment, production revenue and utility costs. The proposed stochastic framework, which utilises a Genetic Algorithm and a penalty function strategy, is found to be successful in obtaining profitable and feasible column designs for many design scenarios including binary and multicomponent mixtures, single duty and multipurpose columns, as well as for regular and complex column configurations. The method can also be used with column models of different complexity. Given a set of design specifications and separation requirements, the optimal number of stages, reboiler duty, reflux profiles, product recoveries, time interval of each distillation tasks, process allocation and number of batches can be obtained. Several design case studies are presented and a comparison of optimal designs for various design scenarios, such as different production time, capital costs, process allocation and mixture characteristics, are discussed.

Separation and Recovery of Dimethylnaphthalene Isomers from Light Cycle Oil by Distillation‐Extraction Combination

Light cycle oil (LCO) contains a lot of valuable aromatic components, including 2,6‐dimethylnaphthalene (2,6‐DMNA) that is focused as the elementary raw material for engineering plastic (PEN plastic) and polymer liquid crystal. We investigated the separation and recovery of dimethylnaphthalene (DMNA) isomers by distillation‐extraction combination as the pretreatment operation to separate and purify 2,6‐DMNA from LCO. The concentration of DMNA isomers from LCO was tested by batch distillation operation. Distillate with DMNA isomers of high concentration, such as 30.63 wt%, was recovered by mixing distillates distilled at 255 to 278°C. Furthermore, equilibrium extraction to investigate separation between DMNA isomers and paraffin components in the distillate was carried out using the mixture oil added a small quantity of n‐decane (DEC) to the distillate recovered through batch distillation operation as raw material and the aqueous N,N‐dimethylforamide as a solvent. Selectivity of DMNA isomers in reference to DEC increased by increasing the solvent moisture and the mass ratio of solvent to raw material, whereas, selectivity of DMNA isomers in reference to DEC decreased by increasing the operation temperature. The process of separation and recovery for DMNA isomers from LCO was studied by using the experimental results obtained from each operation (distillation, extraction) of this work.

Prediction of the Operating Conditions in a Batch Distillation Column Using a Shortcut Method

A shortcutprocedureas quick, easy-to use methodfor design and simulation of mul- ticomponent batch distillation is used to predict the operatingcondition of recoveringxylene from solvent in an existing batch distillation column in benzol refinery. Theprocedure can be used to investigate the effect of the operatingparameters on the operation of columnfor three possible modes of batch distillation operations;constant reflux, variable reflux and step wise change in the reflux ratio. It is shown that step wise change in the reflux ratio, in comparison with a fixed ratio mode, can significantly reduce the requiredoperation time and makes the operation more econom- ical even at high reflux ratios. Applying the procedure in a batch distillation column (National Iranian Steel Cooperation) with 35 bubble-cap trays, mixed-xylenes were produced in a desired purity of 95% with a recovery of 92.5%from afeedstock containing 40% xylenes.

Closed operation of multivessel batch distillation: Experimental verification

AbstractThe multivessel batch distillation column, as well as conventional batch distillation, can be operated in a closed (total reflux) mode where the products are collected in vessels along the column. A previously proposed and simulated feedback control strategy for the closed operation is to indirectly adjust the vessel holdups by using the reflux flow out of the vessel to control the termperature at some location in the column section below. The feasibility of this scheme is demonstrated here experimentally on a laboratory‐scale multivessel column. The experimental column consists of a reboiler, two intermediate vessels, and an accumulator, where a mixture of methanol–ethanol–propanol–butanol is separated into almost pure components. The first published experimental work on the closed operation of batch distillation is presented, as well as its results on the operation of a multivessel column.

Simulated annealing for the optimization of batch distillation processes

Batch distillation processes are widely used in the chemical industry. In this work, we consider the optimization of such processes by simulated annealing. Although this method is stochastically in nature, it has two well-known advantages: it can be readily connected to highly sophisticated simulation codes and it converges towards a global optimum. According to the characteristics of batch distillation operation we propose to use a two-step computation approach. A feasible strategy (admissible control) will be searched for in the first step and it will be optimized in the second step. The approach has been applied to a model of a pilot batch distillation plant. These results show the potential of the method for developing optimal operation strategies for batch chemical processes.

RBDOPT: a general-purpose object-oriented module for distributed campaign optimization of reactive batch distillation

Reactive batch distillation optimization (RBDOPT) provides a general framework for the simulation and the optimization of multicomponent batch distillation with or without chemical reactions. It models the distillation process as a differential algebraic equation (DAE) system and can handle various modes of operation such as continuous flow of one of the reactants, intermediate feed and inverted distillation. Physical property estimates are obtained from Physical Property Data Service (PPDS) that supports a large number of species and routes to model non-ideal behaviour. RBDOPT is designed specifically for determining optical campaign policies for reactive batch distillation systems with minimal input from a user. Coded in an object-oriented environment (C++), it uses distributed computing techniques to achieve a speedup nearly equal to the number of control variables while solving the optimal control problem. This paper highlights the main features of RBDOPT and demonstrates its application to the optimization of reactive batch distillation operation.

Optimal batch distillation control based on specific measures

Two independent measures characterise a single batch distillation run: the degree of separation difficulty, which indicates the difficulty at the start and the degree of exhaustion, which indicates bottom exhaustion at the end of the run. If one of both measures remains within bounds, then constant quality control appears to be the best control policy. It has been proven in the literature that the application of slop recycling increases the production rate. One of the goals of this study is to derive simple scheduling models based on specific measures for the optimal operation of batch distillation with slop recycling. Simulation studies for a cyclic pseudo-steady state operation over a broad range of degrees of difficulty for binary and ternary distillations are performed. Also the influence of the tray hold-up has been studied. All simulations show that at maximum production rate the degree of separation difficulty balances the degree of exhaustion (dependent variable in the optimum). The slop recycling strategy keeps the degree of exhaustion during the production phase and the degree of difficulty during the slop phase within bounds. As a result, the improvement of slop recycling at constant quality control compared to constant reflux control is 15–20% for difficult separation and can amount to more than 35% for relatively easy separations. The resulting production time appears to have a linear relation with the average separation difficulty. This relation has been experimentally verified.

Efficient Simulation of Batch Distillation Processes by Using Orthogonal Collocation

Orthogonal collocation on finite elements is applied to discretize the DAE system for the simulation of multiple-fraction batch distillation processes. A detailed dynamic tray-by-tray model is used to describe batch columns more accurately which, however, leads to a set of model equations composed of nonlinear DAEs with a fairly high dimension. In addition, batch distillation operation usually takes a long period of time and therefore it costs large computational expense to simulate such processes. The use of orthogonal collocation is demonstrated to obtain a stable and highly accurate algebraic representation of the differential equations so as to improve the computational efficiency significantly. Because of the orthogonality of the polynomials introduced to approximate the state variables within a time interval, large integration steps can be taken with the collocation approximation without reducing the computational accuracy. Through simulation of two real batch distillation processes it is found that with this discretization approach 50% CPU time can be saved in comparison to the implicit Euler method normally used.

Calculation of parametric sensitivity in binary batch distillation

This paper provides a comprehensive analysis of parametric sensitivity of batch distillation operations to perturbations in the feed composition. Three column arrangements are considered: batch rectifiers, batch strippers and total-reflux columns. The perturbation dynamics is parameterized in such a way as to allow the analytical calculation of the sensitivity function in the whole composition range, for both sharp and non-sharp separations. This makes it possible to determine a priori which operating conditions and system parameters favor sensitivity of the nominal state variable profiles, and to calculate to which extent parametric sensitivity is exhibited by a certain batch distillation operation. For conventional batch rectifiers, it is shown that there exists a limiting value r top of the reflux ratio above which there is a ‘sensitive’ operating region characterized by a linear increase of the sensitivity function with respect to the concentration of the heavy component in the reboiler; the higher the reflux ratio, the wider this sensitive operating region. For operations with r< r top, the sensitivity function is independent of the reflux ratio. For batch strippers, it is found that sensitive and non-sensitive operating regions are located somewhat symmetrically with respect to the case of batch rectifiers. However, the sensitivity function profiles are not symmetrical to those exhibited by regular batch columns. Finally, for columns operated at total reflux with a ‘balanced feed’, it is shown that if the feed is ‘very’ light or ‘very’ heavy, the transient behavior of the bottom composition sensitivity function is either always increasing or always decreasing. The parametc sensitivity in total-reflux operations appears higher than the one exhibited in finite-reflux-ratio operations.