A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> Abstract In this paper two design techniques, based on mathematical programming, for the synthesis of mass exchange networks (MENs) are compared. Problems not generally dealt with in the literature, and associated with these techniques, are highlighted. A method is presented for generating several feasible initial solutions to avoid accepting poor local solutions as final designs. A method of handling the discontinuity of the Kremser equation used for determination of the number of stages is also discussed. The new method does not rely on the use of integer variables. In addition, a method of generating MINLP solutions that feature integer stage-numbers is also presented. It is shown that insight-based superstructures assuming vertical mass transfer may fail to include the optimal structure of the MEN. Solutions of several MEN synthesis example problems are presented. Advanced pinch and mathematical programming-based solutions are compared. Both simple and advanced capital costing functions are used for the estimation of the total annual cost (TAC) of the MENs. <s> BIB001 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> Abstract The paper deals with the synthesis problem of mass exchange networks (MEN's) for waste minimization by adopting a mathematical programming approach based on the stage-wise superstructure representation of the MEN's, analogous to the one introduced by [Yee, T. F., & Grossmann, I. E. (1990a). Simultaneous optimization models for heat integration. I. Area and energy targeting and modeling of multi-stream exchangers. Computers and Chemical Engineering 14, 1151; Yee, T. F., & Grossmann, I. E. (1990b). Simultaneous optimization models for heat integration. II. Heat exchanger network synthesis. Computers and Chemical Engineering 14, 1165] for synthesis of heat exchange networks (HEN's). This stage-wise superstructure-based representation cannot only handle multiple transferable components and reactive separating agents directly, but also be extended to include regeneration networks straightforwardly. Not using any heuristics that are based on the concept of pinch points, the proposed superstructure-based representation for MEN's is formulated as a mixed-integer nonlinear programming (MINLP) optimization model, and therefore the operating cost for the external lean mass separating agents as well as the regenerating agents and the annualized equipment cost for exchange units can be minimized simultaneously. Four benchmark examples from literatures—including those with single recovery component, multiple waste components, reactive mass separating agent, and regenerating streams—are examined to illustrate the applicability of proposed approach for synthesis of various MEN's. <s> BIB002 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> A large amount of low grade energy is often wasted without heat recovery in the process industry. Over-the-fence heat integration for district heating (DH) can be suggested to utilize this waste heat and therefore alleviate the carbon footprint of the integrated energy system. The economic performance of over-the-fence process integration depends on the cost of fuel, electricity and distance for the transfer of waste heat to DH network. A new design methodology has been developed to systematically evaluate the economic benefit of integration of low grade heat with local DH networks. A site-wide analysis tool using site composite profiles is incorporated in the developed design method in order to identify the quality and quantity of low grade heat available from the site. The optimization framework developed identifies economically acceptable distance for the over-the-fence heat recovery from the industrial site to local community, subject to economic parameters and engineering constraints. A case study has been carried out to demonstrate the design methodology, and the results from the case study illustrate techno-economic and engineering barriers in practice for the implementation of low grade heat recovery beyond the site. <s> BIB003 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> Abstract Over the last decade, energy prices in China have risen dramatically. At the same time, extensive use of coal fired energy provision systems in industry has led to serious environmental and economic problems translating to an economic damage of an estimated 10% of the Gross Domestic Product. This has led to increasing awareness in the process industries of the need to save energy whilst replacing conventional energy sources with renewable ones. An energy audit was conducted for a soy sauce production facility in Beijing, which aimed to reduce its thermal energy demand through process intensification and to integrate renewable energy. Their current supply of thermal energy came directly from a district steam network, which was both directly consumed and downgraded via heat exchangers. It was determined that the best two solar integration locations would be in the pre-heating/mixing of raw ingredients to 60 °C and the subsequent direct steaming of the mixture to 120 °C. Three different systems for supplementing steam were investigated: (1) a traditional solar thermal heating system; (2) a system consisting of mono crystalline photovoltaic panels coupled with either a resistance heater or electric steam generator; and (3) a cascading system consisting of two types of solar thermal collectors, photovoltaic panels, and an electric steam generator. Comparisons of systems 1 and 2 were made for the heating of mixing water, and systems 1, 2, and 3 for saturated steam generation. Results showed that for the heating of process water, flat plate solar collectors performed best with an estimated 20 year Levelised Cost of Energy of 0.063 €/kW h. Steam generation was most cost effective with a cascade system of photovoltaic and flat plate collectors, with an estimated 20 year Levelised Cost of Energy of 0.145 €/kW h. The model predicts that integration of this technology would lead to a reduction of 14% in heating utility demand. <s> BIB004 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> Abstract Distillation units require huge amounts of energy for the separation of the multicomponent mixtures involved in refineries and petrochemical industries. The overall efficiency of the distillation column system is determined from the trade-offs of the Operating Expenditures (OPEX) and Capital investment cost (CAPEX), as there is a strong interaction between the distillation columns and the Heat Exchanger Network (HEN) of the interconnecting streams. In this paper, a systematic Mixed Integer Non-Linear Programming (MINLP) optimization methodology for process integration of distillation column complex is presented. The highly nonlinear rigorous models of the distillation column and phase change are being substituted with simple surrogate models that generate operating responses with adequate accuracy. The methodology is applied on two case studies of the aromatics separation PARAMAX complex. The results illustrate significant reductions on the Total Annualized Cost. With a scope limited to the benzene and toluene columns, the gain reaches about 15%. <s> BIB005 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> This article first reviews recent developments in process synthesis and discusses some of the major challenges in the theory and practice in this area. Next, the article reviews key concepts in optimization-based conceptual design, namely superstructure representations, multilevel models, optimization methods, and modeling environments. A brief review of the synthesis of major subsystems and flowsheets is presented. Finally, the article closes with a critical assessment and future research challenges for the process synthesis area. <s> BIB006 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Recent highlights on heat and mass exchanger network synthesis <s> Given the rising levels of greenhouse gases and the dependence of power generation on fossil fuels, power system planning with emission constraint is of crucial importance. The objective of emission constrained power sector planning is to identify an optimal energy mix, capable of supplying the required amount of electrical energy while simultaneously keeping emissions within a predefined limit. Cost minimisation is the common objective in power sector planning. Additionally, the choice of one power plant over another involves considering a large number of social, environmental, and economic factors. A multi-objective approach is better suited to address such a complex problem. In this paper, Pinch Analysis, a single objective optimisation method, is modified to address multi-objective problems. It is then applied to simultaneously minimise the land footprint, water footprint, and capital cost associated with energy generation for the Indian power sector. A graphical solution space containing all Pareto optimal solutions for a three-objective problem is also presented. It is seen that for India, the energy mix is dominated by photovoltaic and carbon capture enabled coal power plants. The energy mix for least water footprint contains only photovoltaic power plants while that for least land footprint has a mix of wind, nuclear, small hydel, photovoltaic and biomass. Capital investment is the minimum when biomass and nuclear power plants, along with carbon capture enabled coal plants supply the demand, making biomass the only renewable to feature in the cost optimal mix. Existing coal power plants continue to supply over 35% of the energy requirements for the entire solution space. The overall results highlight the importance of solar PV and carbon capture technology. <s> BIB007
Heat and mass exchanger network synthesis remains an area of continuous development in process engineering due to the current trend of increasing energy and material costs. Heat and mass exchanger networks use available heat in a process through the exchange that occurs between hot and cold process streams to decrease energy demands, utility costs and capital investment in most industrial processes. Integration of heat and mass exchanger networks for industrial applications can improve the economics of plant operation. Several advances have been reported for the design of heat and mass exchanger networks using approaches which involve the pinch point and mathematical programming. Recently, simultaneous design and optimization methodologies have been proposed BIB005 . Due to the complex nature of most mathematical equations involved in the synthesis of heat and mass exchanger networks, the application of mathematical programming in process synthesis could be achieved by simplifying various superstructures and model equations through the use of simplified capital cost functions. Mathematical programming has also shown significant potentials in solving HENs and MENs problem with the recent advancement in computing technology. It deals mainly with heat integration, synthesis of heat and mass exchanger networks or synthesis of process schemes and process subsystems. It is remarkable to note that the final effect of the synchronized method is not only the expected reduction in energy consumption, but also the reduction in raw material consumption. The scope of process integration through mathematical programming has improved in recent times and it can be applied in process industries to optimize heat and mass exchanger networks for carbon emission reduction and water minimization BIB003 BIB004 . The foremost role of mathematical programming in synthesis of HENs and MENs is to improve concepts (and also create new ones) by expressing them in precise forms to obtain ideal and feasible solutions of complex problems BIB006 . Apposite trade-offs between raw materials, operating and investment costs as well as product income can be established by applying mathematical programming in overall systems concurrently, thus attaining accurately integrated details. Mathematical programming techniques in the synthesis of HENs and MENs require postulation of a superstructure of alternatives (whether it involves a high level aggregated model or a detailed model). The main issues associated with postulating superstructures for HENs and MENs include the major type of representations that can be used, its modelling implications, and the feasible alternatives that must be included to guarantee that the global optimum is not ignored. To analytically generate superstructures that contain all the alternatives of interest in a process such as CO 2 capture, a graphical-theoretical approach with polynomial complexities is proposed in this review to find all interconnections in process networks with nodes for processes and chemicals adequately specified. Apart from the selection of superstructures, the choice of a detailed optimization model is also necessary for an effective energy and material minimization. Postulation of superstructures and selection of optimization models will be a very reliable procedure in synthesizing process networks for waste minimization during CO 2 capture. Mathematical programming in combination with pinch analysis can be used in a hybrid manner to synthesize a combined heat and mass exchanger network that will minimize both energy consumption and excessive material usage simultaneously during CO 2 capture. Pinch analysis techniques should be used to set the energy targets, while mathematical programming can then be used to synthesize the networks by building upon the existing SYNHEAT model in General Algebraic Modeling System (GAMS) software. A detailed methodology for this is diagrammatically presented in Fig. 12 . Aggregated mixed-integer nonlinear programming (MINLP) models can also be used in mathematical programming. This reduces the computational difficulties associated with mathematical programming and improves the synthesis process. The aggregated MILP model suitable for studies of this nature is the transshipment model. The model uses pinch location methods to calculate the minimum amount of energy expended and material consumed during CO 2 capture BIB007 . This procedure is easy to embed in any mathematical programming model for process synthesis. It can also perform a simultaneous flowsheet synthesis and heat integration because it has both mathematical programming and pinch analysis integrated in it BIB002 BIB001 .