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Mahmoud M. El-halwagi - One of the best experts on this subject based on the ideXlab platform.

  • Chapter 5 – Synthesis of Mass-Exchange Networks
    Sustainable Design Through Process Integration, 2017
    Co-Authors: Mahmoud M. El-halwagi
    Abstract:

    Mass-Exchange units are ubiquitously used in industrial facilities. A Mass Exchanger is any direct-contact Mass-transfer unit that employs a Mass-separating agent (MSA) or a lean phase (e.g., a solvent, an adsorbent, a stripping agent, an ion Exchange resin) to selectively remove certain components (e.g., pollutants, products, byproducts) from a rich phase (e.g., a waste, a product). Examples of Mass-Exchange operations include absorption, adsorption, stripping, solvent extraction, leaching, and ion Exchange. Appendix 2, Modeling of Mass-Exchange Units for Environmental Applications, provides an overview of the principles of modeling, designing, and operating individual Mass-Exchange units. In many industrial situations the problem of selecting, designing, and operating a Mass-Exchange system should not be confined to assessing the performance of individual Mass Exchangers. Instead, multiple Mass Exchange operations are involved and several candidate MSAs are considered. In such situations, there are several rich streams (sources) from which Mass has to be removed and MSAs can be used for removing the targeted species. Therefore, adopting a systemic network approach can provide significant technical and economic benefits. In this approach, a Mass-Exchange system is selected and then designed by simultaneously screening all candidate Mass-Exchange operations to identify the optimum system. This chapter defines the problem of synthesizing Mass-Exchange networks (MENs) discusses its challenging aspects and provides graphical and algebraic approaches for the targeting and synthesis of MENs.

  • Systematic Synthesis of Mass Exchange Networks for Multicomponent Systems
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Linlin Liu, José María Ponce-ortega, Mahmoud M. El-halwagi, Pingjing Yao
    Abstract:

    The synthesis of Mass Exchange networks (MENs) is an important systematic tool for screening Mass-separating agents (MSAs) and satisfying the Mass transfer demands while considering process, enviro...

  • Synthesis of Multi-component Mass-Exchange Networks
    Chinese Journal of Chemical Engineering, 2013
    Co-Authors: Linlin Liu, José María Ponce-ortega, Mahmoud M. El-halwagi, Pingjing Yao
    Abstract:

    Abstract This paper presents a superstructure-based formulation for the synthesis of Mass-Exchange networks (MENs) considering multiple components. The superstructure is simplified by directly using the Mass separation agents (MSA) from their sources, and therefore the automatic synthesis of the multi-component system involved in the MENs can be achieved without choosing a ‘key-component’ either for the whole process or the Mass Exchangers. A mathematical model is proposed to carry out the optimization process. The concentrations, flow rates, matches and unit operation displayed in the obtained network constitute the exact representation of the Mass Exchange process in terms of all species in the system. An example is used to illustrate and demonstrate the application of the proposed method.

  • Chapter 20 – Synthesis of Combined Heat and Reactive Mass-Exchange Networks
    Sustainable Design Through Process Integration, 2012
    Co-Authors: Mahmoud M. El-halwagi
    Abstract:

    Publisher Summary This chapter discusses the problem of synthesizing combined heat and reactive Mass-Exchange networks (CHARMEN). Because of the interaction of Mass and heat in the CHARMEN, one should synthesize the Mass-Exchange network (MEN) and the heat-Exchange network (HEN) simultaneously. This is a linear-programming formulation whose solution determines the optimal flow rate and temperature of each substream and heating/cooling utilities. In a typical MEN, there is a strong interaction between Mass and heat. For instance, the Mass-Exchange equilibrium relation of a Mass-separating agent (MSA) is affected by its temperature. Therefore, heating or cooling may be beneficial to the performance of the MEN. However, heating/cooling may incur an additional cost. The objective is to minimize the cost of MSAs and heating/cooling utilities. However, heating/cooling may incur an additional cost. Indeed, there is a trade-off between the Mass and heat objectives. Ideally, it is desired to minimize the total cost of heat and Mass Exchange. Because the Mass-Exchange equilibrium relations are dependent upon temperature and the selection of optimal Mass-Exchange temperatures is an important element of design, the selection of these temperatures should involve a trade-off between the cost of the MSAs and the cost of the heating/cooling utilities.

  • Pollution Prevention through Process Integration - CHAPTER TWO – Modeling of Mass-Exchange Units for Environmental Applications
    Pollution Prevention through Process Integration, 1997
    Co-Authors: Mahmoud M. El-halwagi
    Abstract:

    This chapter presents an overview of the basic modeling principles of Mass-separating agent (MSA) induced separations, referred to as Mass-Exchange units. Mass-Exchange operations are indispensable for pollution prevention. Within a Mass-integration framework, Mass-Exchange operations are employed in intercepting sources by selectively transferring certain undesirable species from a number of waste streams (sources) to a number of MSAs. The realm of Mass Exchange includes several operations, such as absorption, adsorption, extraction, ion Exchange, leaching, and stripping. The main objective of a Mass Exchanger is to provide appropriate contact surface for the rich and the lean phases. Such contact can be accomplished by using various types of Mass-Exchange units and internals. In particular, there are two primary categories of Mass-Exchange devices: multistage and differential contactors. In a multistage Mass Exchanger, each stage provides intimate contact between the rich and the lean phases followed by phase separation. In differential contactors the two phases flow through the Exchanger in continuous contact throughout without intermediate phase separation and recontacting.

B.k. Srinivas - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of reactive Mass-Exchange networks with general nonlinear equilibrium functions
    AIChE Journal, 1994
    Co-Authors: B.k. Srinivas, Mahmoud M. El-halwagi
    Abstract:

    The problem of synthesizing reactive Mass-Exchange networks (REAMENs) is addressed for which the equilibrium relations governing the transfer of a certain species from rich streams to reactive Mass-separating agents are nonlinear (convex and/or nonconvex). Previously developed synthesis procedures for REAMENs are not applicable to such cases, since they were developed for cases of linear and/or convex equilibria. Two peculiar phenomena are associated with REAMENs with general nonlinear equilibria: the location of a Mass-Exchange pinch point is not restricted to supply compositions of streams; Mass Exchangers may straddle the pinch point even for networks featuring the minimum cost of Mass-separating agents. To account for such intriguing characteristics, a systematic procedure is developed to synthesize cost-effective REAMENs with general nonlinear equilibria. In addition, a robust solution procedure is devised to guarantee the identification of the global solution of the developed optimization programs. Applicability and usefulness of the proposed synthesis procedure are demonstrated via a case study on the desulfurization of gaseous wastes from a coal-to-methanol plant.

  • Synthesis of combined heat and reactive Mass-Exchange networks
    Chemical Engineering Science, 1994
    Co-Authors: B.k. Srinivas, Mahmoud M. El-halwagi
    Abstract:

    Abstract In this work we introduce the problem of synthesizing combined heat and reactive Mass Exchange networks “CHARMENs”. The synthesis task involves the preferential transfer of a certain species from a set of rich streams to a set of lean streams and at the same time accomplish a specified heat transfer task in a cost effective manner. The economic objectives of Mass Exchange and heat recovery are in general incompatible and need to be addressed simultaneously. The proposed work introduces a systematic and generally applicable procedure to trade-off the two objectives and synthesize a CHARMEN. First, we derive a number of important properties of the problem. Based on these characteristics, a two-stage targeting procedure is developed. In the first stage, the minimum operating cost “MOC” of the network is identified via a mixed-integer nonlinear program “MINLP”. A shortcut linear formulation is also devised to identify a near-optimum MOC solution which may be used as an initial guess for the MINLP. The optimum solution to the MOC problem results in a natural decomposition of the original CHARMEN problem into two independent subproblems that may be solved to identify the minimum number of heat and reactive Mass Exchangers. The applicability of the synthesis procedure is demonstrated by tackling a case study on the desulfurization of gaseous wastes with simultaneous heat recovery.

  • Synthesis of reactive Mass-Exchange networks
    Chemical Engineering Science, 1992
    Co-Authors: Mahmoud M. El-halwagi, B.k. Srinivas
    Abstract:

    The synthesis of a network of reactive Mass Exchangers involves the same challenges as in synthesizing physical MENs. The problem is further compounded by virtue of the reactivity of the MSAs. Typically, reactive MSAs have a greater capacity and selectivity to remove an undesirable component than physical MSAs. Furthermore, because they react with the undesirable species, it may be possible to convert pollutants into other species that may either be reused within the plant itself or sold. The problem of synthesizing rea ctive m ass- e xchange n etworks (REAMENs) was developed, along with systematic techniques for its solution. The first step in synthesizing a REAMEN is to establish the conditions for which the reactive Mass Exchange is thermodynamically feasible. To establish the conditions for thermodynamic feasibility of reactive Mass Exchange, it is necessary to invoke the basic principles of Mass transfer with chemical reactions. After a procedure for establishing the corresponding composition scales for the rich-lean pairs of streams has been outlined, it is possible to develop the CID. However, it should be noted that the conversion among the corresponding composition scales may be more laborious because of the nonlinearity of equilibrium relations. The necessary thermodynamic concepts are covered in the chapter along with chemical equilibrium, which is tackled in a manner that renders the REAMEN synthesis task close to the MEN problem. Finally, an optimization-based approach is presented and illustrated by a case study.

A. R. Aliev - One of the best experts on this subject based on the ideXlab platform.

Duncan M. Fraser - One of the best experts on this subject based on the ideXlab platform.

  • Supply-based superstructure synthesis of heat and Mass Exchange networks
    Computers & Chemical Engineering, 2013
    Co-Authors: O. S. Azeez, Adeniyi J. Isafiade, Duncan M. Fraser
    Abstract:

    Abstract A new simultaneous mixed integer non-linear programing (MINLP) approach to heat Exchange network synthesis (HENS) and Mass Exchange network synthesis (MENS) is presented. This supply-based superstructure (SBS) approach uses the supply temperatures/compositions of all the streams (including utilities) present in the synthesis problem to define heat/Mass Exchange superstructure intervals. The intermediate temperatures/compositions are variables used in the optimization of the network total annual cost (TAC). The ability of each stream to Exchange heat/Mass in any interval in the SBS is subject to thermodynamic/Mass transfer feasibility. The paper presents the mathematical formulations for optimizing the TAC for HENS and MENS. The SBS synthesis technique has been applied to nine literature problems involving both HENS and MENS. The solutions obtained are in the same range as those in the literature, with one solution being the lowest of all.

  • Hybrid synthesis method for Mass Exchange networks
    Computer Aided Chemical Engineering, 2003
    Co-Authors: A. K. Msiza, Duncan M. Fraser
    Abstract:

    Abstract A hybrid tool for the synthesis of Mass Exchange networks is presented in this paper. The tool uses targets to measure the quality of solutions generated by a mixed-integer non-linear (MINLP) model. The components making up the hybrid tool are a total annual cost target of the expected flowsheet, a physically meaningful initial flowsheet, a driving force diagram and an MINLP model. The total annual cost target represents the best cost scenario for the flowsheet, an initial flowsheet is used to initialise the MINLP solver and the driving force plot assists the designer to generate alternative initial solutions to improve the generated MINLP solution. The hybrid tool produces Mass Exchange networks whose total annual costs are within 10% of previously reported pinch solutions and networks that are similar or better than those obtained from the MINLP approach alone. The designer has confidence in the quality and optimality of the solutions due to the available targets and the visual driving force diagrams.

  • Retrofit of Mass Exchange networks
    Computer Aided Chemical Engineering, 2001
    Co-Authors: Duncan M. Fraser, N. Harding, C. Matthews
    Abstract:

    Publisher Summary This chapter examines the retrofit of an industrial Mass-Exchange network for the removal of hydrogen sulphide from a set of gaseous streams to reduce sulphur emission from the plant. The system used by Sasol for hydrogen sulphide absorption from the gas streams is one in which the gas–liquid contact is effected in three venturi scrubbers with a combined cross- and co-current flow arrangement. Previous Mass-Exchange network design was only for counter-current systems, so one needed to develop new methodology for solving this system. The new method is applied to the system to evaluate the impact of three different strategies on the overall sulphur emission from the plant: segregation of the gas streams, increase of contact time in the scrubbers, and increase of the gas-flow rate through the scrubbers. The chapter concludes by evaluating the relative merits of these alternative strategies.

  • Retrofit of Mass Exchange networks using pinch technology
    AIChE Journal, 2000
    Co-Authors: Duncan M. Fraser, N. Hallale
    Abstract:

    The purpose of this article is to demonstrate that the Pinch Technology approach for the retrofit of heat Exchange networks (HENs) may be successfully applied to the retrofit of Mass Exchange networks (MENs).

R. Z. Aliev - One of the best experts on this subject based on the ideXlab platform.