The integration of entire supply and value chain into a closed loop network is gaining more im-portance in recent times in order to ensure a business to be economically and environmentally sustainable with the changing trends in business... more
The integration of entire supply and value chain into a closed loop network is gaining more im-portance in recent times in order to ensure a business to be economically and environmentally sustainable with the changing trends in business and social environments, growing environmental consciousness in the society and government legislations to protect the environment as well as the business. In this context, this paper considers a multi-echelon closed loop supply chain network design with forward and reverse logistics components. An attempt has been made to develop a mixed integer non-linear programming model for this problem with different costs so that the sum of the total cost is minimized subject to different constraints pertaining to capacities of the entities of the system, demands of first customers and second customers. A generalized model is presented and then its application is illustrated using an example problem by solving the model using LINGO14. This model forms as a to...
The synthesis of heat exchanger networks (HENs) has mainly been done through the use of approximate models for each of the individual heat exchangers that comprises the network. These approximate models do not adequately take into account... more
The synthesis of heat exchanger networks (HENs) has mainly been done through the use of approximate models for each of the individual heat exchangers that comprises the network. These approximate models do not adequately take into account key parameters such as the overall heat transfer coefficient , TEMA standards, pressure drops, FT correction factors, and multiple shells. These factors can significantly alter the cost of the network. This paper presents a new methodology for the synthesis of heat exchanger networks using detailed heat exchanger design models that takes into account the aforementioned design parameters. The newly developed method involves the following steps. First, a SYNHEAT (Yee and Grossmann, 1990) MINLP model is solved. The individual exchangers for the resulting network are then designed using heuristics, TEMA standards and the Bell-Delaware method. From the designs obtained for these individual exchangers, correction factors are inserted into the SYNHEAT model that account for changes in overall heat transfer coefficient, TEMA choices, pressure drops, Ft correction factors and the effect of multiple shell passes. The SYNEAT model is then rerun and individual exchangers redesigned and the procedure repeated until convergence is achieved. For each iteration the change in each correction factor is limited to avoid the omission of certain solutions. While the methodology cannot guarantee global optimality it can ensure that the synthesised processes are physically achievable and has also been shown to converge on physically meaningful parameters without the explicit formulation of complicated non-linear equations in the MINLP formulation.
The integration of entire supply and value chain into a closed loop network is gaining more importance in recent times in order to ensure a business to be economically and environmentally sustainable with the changing trends in business... more
The integration of entire supply and value chain into a closed loop network is gaining more importance in recent times in order to ensure a business to be economically and environmentally sustainable with the changing trends in business and social environments, growing environmental consciousness in the society and government legislations to protect the environment as well as the business. In this context, this paper considers a multi-echelon closed loop supply chain network design with forward and reverse logistics components. An attempt has been made to develop a mixed integer non-linear programming model for this problem with different costs so that the sum of the total cost is minimized subject to different constraints pertaining to capacities of the entities of the system, demands of first customers and second customers. A generalized model is presented and then its application is illustrated using an example problem by solving the model using LINGO14. This model forms as a tool to compare future meta-heuristics to check the closeness of their solutions with corresponding optimal solutions.
The oil refining industry mainly uses linear programming (LP) modelling tools for refinery optimisation and planning purposes, on a daily basis. LPs are attractive from the computational time point of view; however these models have... more
The oil refining industry mainly uses linear programming (LP) modelling tools for refinery optimisation and planning purposes, on a daily basis. LPs are attractive from the computational time point of view; however these models have limitations such as the nonlinearity of the refinery processes is not taken into account. In addition, building the LP model can be an arduous task that requires collecting large amounts of data. The main aim of this work is to develop approximate models to replace the rigorous ones providing a good accuracy without compromising the computational time, for refinery optimisation. The data for deriving approximate models has been generated from rigorous process models from a commercial software, which is extensively used in the refining industry. In this work we present novel model reduction techniques based upon optimal configuration of artificial neural networks to derive approximate models and demonstrate how these models can be used for refinery-wide energy optimisation.
In this study the effect of petroleum contracts on Iran and Saudi Arabia's oil production trend has investigated. Disaggregated approach has utilized to investigate the effect of petroleum contracts. In this approach, optimal... more
In this study the effect of petroleum contracts on Iran and Saudi Arabia's oil production trend has investigated. Disaggregated approach has utilized to investigate the effect of petroleum contracts. In this approach, optimal production of the fields of above mentioned countries, has been evaluated in two scenarios. Then by summation of production data of all fields, production trend of these two countries has been calculated. In the first scenario, it is assumed that control of oil production is in the hands of host country, while control of production in the second scenario is determined based on the kind of contracts which the host country has had during its oil production history. Based on the estimated production trend of two countries, it is observed that in the case which International Oil Company controls the production, rate of oil extraction is more than the case which production is controlled by the host country. Also by increasing the portion of International Oil Com...
Nowadays, the energy storage systems (ESSs) are widely used in different levels of power systems for dealing with the challenges caused by the integration of renewable energy sources (RESs). Among the ESSs, batteries are more suitable for... more
Nowadays, the energy storage systems (ESSs) are widely used in different levels of power systems for dealing with the challenges caused by the integration of renewable energy sources (RESs). Among the ESSs, batteries are more suitable for being used in microgrids (MGs) at distribution level due to their special features. Therefore, this paper presents a novel approach for the planning of distributed battery energy storage systems (BESSs) to enhance MGs operation, economically. The model is formulated as a mixed-integer nonlinear programming problem (MINLP) and considers various types of BESSs. In order to verify the effectiveness of the proposed approach, it is applied to the IEEE 33-bus network test system and the results are reported. The outcomes show the effectiveness of the proposed model.
Eco-industrial networks are a concept which has received study for almost 30 years as a strategy for improving economics of production facilities while reducing waste. This study focuses on developing a generalized modeling framework in... more
Eco-industrial networks are a concept which has received study for almost 30 years as a strategy for improving economics of production facilities while reducing waste. This study focuses on developing a generalized modeling framework in terms of mixed-integer nonlinear programming of an eco-industrial network. The problem is formulated as a multi-objective optimization with the objective to reduce life-cycle emissions and maintaining favourable economics. This model lends itself as a developmental tool to assess environmental and economic feasibility of applying eco-park concepts to new construction projects. In addition, the model is formulated to determine feasible transportation distances between facilities, select the appropriate transportation technologies and is built with the intention of modification toward stochastic import/export pricing. The sensitivity of the network configuration to variances in the weighting factors placed on economics or environmental emissions is discussed and the results from multiple weighting scenarios are presented. These results show that the estimated reductions in cost and emissions are less significant than those from previously published work but are founded upon a more realistic network model. Based on our findings, the cost for the integrated set of facilities is shown to be reduced by 24% while the emission reduction is observed at 12.7% for the base scenario examined by the earlier models. These results show less promise than the earlier findings but represent a more realistic assessment of the proposed network. The tools developed by this research present a novel approach to facility planning and policy development for chemical industries. As such, the framework presented herein has the potential to impact facility construction/operation and public policy governing industrial producers; additionally, this research contributes an empirical approach for assessing the practicality of establishing eco-industrial networks and provides an approach for further analyses.
Abstract This study makes use of a novel methodology for the synthesis of heat exchanger networks, which is aimed at overcoming the shortcomings associated with the use of shortcut models to represent individual exchangers in the... more
Abstract This study makes use of a novel methodology for the synthesis of heat exchanger networks, which is aimed at overcoming the shortcomings associated with the use of shortcut models to represent individual exchangers in the synthesis network. The new approach entails the use of a number of correction factors to get networks which are based on the use of shortcut models, such as the mixed integer non-linear programming (MINLP) stage-wise superstructure (SWS) of Yee and Grossmann (1990) to more closely represent physically achievable heat exchangers and ensure that the MINLP network topology optimisation step of these models converge on a real design, rather than an approximated one. In this paper, the SWS formulation is used for the generation of an initial network after which its objective function is modified to include the correction factors that force its objective function towards the cost of a network whose individual exchangers are designed using methods such as Bell–Delaware and heuristics. The modified objective function includes parameters that modify the areas obtained by the shortcut based MINLP model so as to more closely represent the areas obtained by the detailed models and also includes a novel method for including the number of shells required for each exchanger duty. The correction factors account for pressure drops, F t correction factors, number of shells, TEMA considerations, and changes to the overall heat transfer co-efficient of each stream match. The methodology is applied to two examples and the solutions are comparable with other solutions obtained in literature and were shown to produce good solutions. The reason that the method is effective is because many potential networks are evaluated during the iterative procedure and the best network, based on the detailed exchanger designs, is chosen. In this way it is possible to use the detailed exchanger designs to “guide” the MINLP optimisation towards more realistic networks and also to generate many different potential networks.
An approach to incorporate inherent safety in the synthesis of heat exchanger networks (HEN) based on optimal layouts is given in this work. Hot and cold streams are produced in a set of facilities and some of these facilities may release... more
An approach to incorporate inherent safety in the synthesis of heat exchanger networks (HEN) based on optimal layouts is given in this work. Hot and cold streams are produced in a set of facilities and some of these facilities may release toxic gas. The geographical allocation where each produced hot and cold stream is then incorporated in the conventional HEN synthesis problem. The number of heat exchangers, area requirement, energy consumption and energy configuration are thus optimally determined. Given are flows, inlet and outlet temperatures for each cold and hot stream as well as sufficient information on cooling and heating services. The annual cost is minimized while allowing for specification of constraints on matches, heat loads and streams splitting. The underlined idea is that inherent safety is achieved when simultaneously producing HEN and optimal facility layouts where risk due to toxic releases is also minimized. The numerical evidence indicates that inclusion of saf...
A general modeling framework for mixture design problems, which integrates Generalized Disjunctive Programming (GDP) into the Computer-Aided Mixture/blend Design (CAM b D) framework, was recently proposed (S. Jonuzaj, P.T. Akula, P.-M.... more
A general modeling framework for mixture design problems, which integrates Generalized Disjunctive Programming (GDP) into the Computer-Aided Mixture/blend Design (CAM b D) framework, was recently proposed (S. Jonuzaj, P.T. Akula, P.-M. Kleniati, C.S. Adjiman, 2016. The formulation of optimal mixtures with Generalized Disjunctive Programming: A solvent design case study. AIChE Journal 62, 1616–1633). In this paper we derive Hull Relaxations (HRs) of GDP mixture design problems as an alternative to the big-M (BM) approach presented in this earlier work. We show that in restricted mixture design problems, where the number of components is fixed and their identities and compositions are optimised, BM and HR formulations are identical. For general mixture design problems, where the optimal number of mixture components is also determined, a generic approach is employed to enable the derivation and solution of the HR formulation for problems involving functions that are not defined at zero (e.g., logarithms). The design methodology is applied successfully to two solvent design case studies: the maximization of the solubility of a drug and the separation of acetic acid from water in a liquid–liquid extraction process. Promising solvent mixtures are identified in both case studies. The HR and BM approaches are found to be effective for the formulation and solution of mixture design problems, especially via the general design problem.
