A review on heat and mass integration techniques for energy and material minimization during CO2 capture
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paper_title: Optimization of Energy and Water Consumption in Corn–based Ethanol

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In this paper we study the simultaneous energy and water consumption in the conceptual design of corn-based ethanol plants. A major goal is to reduce the freshwater consumption and wastewater discharge. We consider the corn-based ethanol plant reported in Karuppiah, et al. AICHE J. 2008, 54, 1499−1525. We review the major alternatives in the optimization of energy consumption and its impact in water consumption. Next, for each of the alternatives we synthesize an integrated process water network. This requires closing the loops for process and cooling water and steam, and implementing the proper treatment for the water streams. We show that minimizing energy consumption leads to process water networks with minimum water consumption. As a result, freshwater use is reduced to 1.54 galwater/galethanol, revealing that it is potentially possible to achieve levels of freshwater consumption that are significantly lower than the ones in current industrial operation and that wastewater discharged can also be reduced.
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paper_title: Facile synthesis of hierarchically porous MgO sorbent doped with CaCO3 for fast CO2 capture in rapid intermediate temperature swing sorption

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Abstract For CO 2 sorbents, a fast sorption rate is as important as the sorption capacity in order to enable efficient CO 2 capture in the treatment of large amounts of emission gas, where the contact time between the sorbent and gas is limited. A facile and environmentally benign method of fabricating advanced sorbents with fast CO 2 sorption for pre-combustion capture was developed by incorporating CaCO 3 into triple salt-promoted MgO sorbents (LiNO 3 , NaNO 3 , and Na 2 CO 3 ) using salt-controllable coprecipitation. The incorporation of Ca into the salt-promoted MgO (MgCa) was effective for controlling the lattice parameter, textural properties, and basicity. The salt-promoted MgCa sorbents had a bi-disperse pore distribution with different range, which contributed to the fast sorption. When 5 mol.% of Ca was doped into the triple salt-promoted MgO, the CO 2 sorption capacity within 10 min was significantly improved (from 6 wt% (MgO) to 43 wt% (MgCa-5%)) at 325 °C. For CO 2 sorption for 10 min at 325 °C and N 2 regeneration for 5 min at 400 °C, the working capacity of MgCa-5% was approximately 30 wt% at the 30 th cycle. Under the same rapid cycling conditions, the sorption capacity was 12 wt% when a wet CO 2 mixture (29 vol% CO 2 , 3 vol% H 2 O, and balance N 2 ) and pure CO 2 was used for sorption and regeneration, respectively. When the regeneration gas contained water vapour, the cyclic sorption capacity decreased to 1–2 wt%. The MgCa sorbents prepared via salt-controllable coprecipitation exhibited high working capacities during the rapid cyclic temperature swing operation at intermediate temperature.
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paper_title: Energy efficiency optimisation for distillation column using artificial neural network models

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This paper presents a neural network based strategy for the modelling and optimisation of energy efficiency in distillation columns incorporating the second law of thermodynamics. Real-time optimisation of distillation columns based on mechanistic models is often infeasible due to the effort in model development and the large computation effort associated with mechanistic model computation. This issue can be addressed by using neural network models which can be quickly developed from process operation data. The computation time in neural network model evaluation is very short making them ideal for real-time optimisation. Bootstrap aggregated neural networks are used in this study for enhanced model accuracy and reliability. Aspen HYSYS is used for the simulation of the distillation systems. Neural network models for exergy efficiency and product compositions are developed from simulated process operation data and are used to maximise exergy efficiency while satisfying products qualities constraints. Applications to binary systems of methanol-water and benzene-toluene separations culminate in a reduction of utility consumption of 8.2% and 28.2% respectively. Application to multi-component separation columns also demonstrate the effectiveness of the proposed method with a 32.4% improvement in the exergy efficiency.
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paper_title: Synthesis of mass exchange networks

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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.
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paper_title: Development of Cost Effective and High Performance Composite for CO 2 Capture in Ca-Cu Looping Process

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Abstract New cost effective and high performance bi-functional composite materials consisting of CaO and CuO supported on Ca 12 Al 14 O 33 have been developed for the calcium-copper (Ca-Cu) looping process. A hydrothermal method has been used to synthesize the materials from low cost precursors. Prepared composites are characterised by X-ray diffraction, scanning electron microscopy together with energy-dispersive spectroscopy mapping, and by crushing strength tests. Long term chemical performances of the materials are tested in a thermo-gravimetric analyser. The composite containing 53 wt% CuO, 22 wt% CaO and 25 wt% Ca 12 Al 14 O 33 shows stable CO 2 capture (∼15 g-CO 2 /100 g composite) and O 2 carrying capacity (∼7 g-O 2 /100 g composite) in long term Ca-Cu multi-cycle, and shows satisfactory mechanical strength compared to reference materials used in the Ca-Cu process.
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paper_title: Modelling and experimental investigation of effects of moisture and operating parameters during the adsorption of CO2 onto polyaspartamide

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Parametric effect of moisture and influence of operating variables on the adsorption behaviour of polyaspartamide during CO2 capture was investigated in this study using experimental and modelling approach. Individual effects of operating conditions (e.g. pressure, temperature and gas flow rates) as well as the effect of moisture on the adsorption capacity of polyaspartamide were methodically investigated using Dubinin–Raduskevich model. Results from the investigations reveal that the presence of moisture in the flue gas had an incremental effect on the adsorption capacity of polyaspartamide; thereby showcasing the potential of polyaspartamide as a suitable hydrophilic material for CO2 capture in power plants. In addition, pressure, temperature and gas flow rates at 200 kPa, 403 K, and 1.5 mL/s, respectively, significantly influenced the CO2 adsorption capacity of polyaspartamide. Physisorption and chemisorption both governed the adsorption process while equilibrium studies at different temperatures showed that Langmuir isotherm could adequately describe the adsorption behaviour of the material with best fit with R2 > 0.95.
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paper_title: Optimization of coal-based methanol distillation scheme using process superstructure method to maximize energy efficiency

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Despite the current methanol distillation system (MDS) touching a highly energy-efficient level, there are still opportunities to cut more corners when moving eyesight from heating media to electricity and work efficiency of rotary equipments. To simultaneously optimize this process for higher overall energy efficiency, methodologically an improved substitute pathway is herein proposed of corresponding process superstructure. In detail, it is an all-in-one integration of heat and work exchanger networks (HEN-WEN), exemplified by a 4-column double-effect methanol distillation scheme popular among Chinese coal-based factories. The completion of this work indicates a hope of potential reductions of pump electricity and reboiler steam consumption of the whole unit by further 68.38% and 15.83%, respectively.
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paper_title: Optimization of energy and water use in multipurpose batch plants using an improved mathematical formulation

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Abstract Presented in this contribution is a formulation that addresses optimization of both water and energy, while simultaneously optimizing the batch process schedule. The scheduling framework used in this study is based on the recent and efficient formulation. This formulation has been shown to result in a significant reduction of computational time, an improvement of the objective function and leads to fewer time points. The objective is to improve the profitability of the plant by minimizing wastewater generation and utility usage. From a case study it was found that through applying only water integration the cost is reduced by 11.6%, by applying only energy integration the cost is reduced by 29.1% and by applying both energy and water integration the cost is reduced by 34.6%. This indicates that optimizing water and energy integration in the same scheduling framework will reduce the operating cost and environmental impact significantly.
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paper_title: Diffusion mechanism and effect of mass transfer limitation during the adsorption of CO2 by polyaspartamide in a packed-bed unit

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ABSTRACTA systematic study of the diffusion mechanism and effect of mass transfer limitation during the adsorption of CO2 onto polyaspartamide is presented using a differential adsorption bed metho...
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paper_title: Heat integration in multipurpose batch plants using a robust scheduling framework

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Energy saving is becoming increasingly important in batch processing facilities. Multipurpose batch plants have become more popular than ever in the processing environment due to their inherent flexibility and adaptability to market conditions, even though the same flexibility may lead to complexities such as the need to schedule process tasks. These are important features to producing high value added products such as agrochemicals, pharmaceuticals, polymers, food and specialty chemicals where the demand has grown in recent decades. Many current heat integration methods for multipurpose batch plants use a sequential methodology where the schedule is solved first followed by heat integration. This can lead to suboptimal results. In this paper, the heat integration model is built upon a robust scheduling framework. This scheduling formulation has proven to lead to better results in terms of better objective values, fewer required time points and reduced computational time. This is important as inclusion of heat integration into a scheduling model invariably complicates the solution process. The improved scheduling model allows the consideration of industrial sized problems to simultaneously optimize both the process schedule and energy usage. Both direct and indirect heat integration are considered as well as fixed and variable batch sizes.
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paper_title: Carbon dioxide capture with concentrated, aqueous piperazine

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Abstract Concentrated, aqueous piperazine (PZ) has been investigated as a novel amine solvent for carbon dioxide (CO2) absorption. The CO2 absorption rate of aqueous PZ is more than double that of 7 m MEA and the amine volatility at 40 °C ranges from 11 to 21 ppm. Thermal degradation is negligible in concentrated, aqueous PZ up to a temperature of 150 °C, a significant advantage over MEA systems. Oxidation of concentrated, aqueous PZ is appreciable in the presence of copper (4 mM), but negligible in the presence of chromium (0.6 mM), nickel (0.25 mM), iron (0.25 mM), and vanadium (0.1 mM). Initial system modeling suggests that 8 m PZ will use 10–20% less energy than 7 m MEA. The fast mass transfer and low degradation rates suggest that concentrated, aqueous PZ has the potential to be a preferred solvent for CO2 capture.
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paper_title: Forty years of Heat Integration: Pinch Analysis (PA) and Mathematical Programming (MP)

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Process Integration (PI) supporting Process Design, Integration, and Optimisation has been around from the early 1970s. PI was developed originally from Heat Integration, which remains the cornerstone for PI continuous advance. It has been closely related to the development of Chemical, Mechanical and Power Engineering supported by the extended implementation of mathematical modelling, simulation and optimisation, and by the application of information technology. Its development has accelerated over the years as its methodology has been able to provide answers and support for important issues regarding economic development — better utilisation and savings regarding energy, water, and other resources. This contribution is targeting towards providing at least a short overview of its historical development, achievements, and future challenges.
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paper_title: Carbon Dioxide Absorption with Aqueous Potassium Carbonate Promoted by Piperazine

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Publisher Summary ::: This chapter presents thermodynamic and kinetic data collected for aqueous blends of piperazine (PZ) and potassium carbonate (K2CO3). Amine and potassium carbonate solvents have proven useful for the removal of CO2 from natural gas and H2. Researchers have shown that blending amines accelerates the absorption process. Mixtures of K+ and PZ have been investigated in a wetted-wall column at 40 to 80°C, typical conditions for an industrial absorber. The addition of 0.6 m PZ to 20 wt% (3.6 m) K2CO3 increases the rate of CO2 absorption by a factor of ten from the value in unpromoted solutions at 60°C. The addition of PZ increases the heat of absorption from 4 kcal/mol in 3.6 m K+ to 10 kcal/mol when 0.6 m PZ is added. The capacity, ranging from 0.4 to 0.7 mol- CO2/kg-H2O, approaches that of monoethanolamine (MEA) solutions and seems to be a strong function of K+ concentration. Speciation of the solution was obtained using proton nuclear magnetic reasonance (NMR), verifying and quantifying the presence of three PZ species. An equilibrium model and a rate model were developed to predict system speciation, equilibrium, and CO2 absorption rate. The model predicts that 3.6 m K+ increases the specific rate constant of PZ by a factor of five from its value in water. Piperazine is expected to accelerate absorption rates while K2CO3 retains a low heat of absorption. Also, the reaction of carbonate in bulk solution is expected to improve solvent capacity.
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paper_title: Design and analysis of heat exchanger networks for integrated Ca-looping systems

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One of the main challenges of carbon capture and storage technologies deals with the energy penalty associated with CO2 separation and compression processes. Thus, heat integration plays an essential role in the improvement of these systems’ efficiencies. CO2 capture systems based on Ca-looping process present a great potential for residual heat integration with a new supercritical power plant. The pinch methodology is applied in this study to define the minimum energy requirements of the process and to design four configurations for the required heat exchanger network. The Second Law of Thermodynamics represents a powerful tool for reducing the energy demand since identifying the exergy losses of the system serves to allocate inefficiencies. In parallel, an economic analysis is required to asses the cost reduction achieved by each configuration. This work presents a combination of pinch methodology with economic and exergetic analyses to select the more appropriate configuration of heat exchanger network. The lower costs and minor destroyed exergy obtained for the best proposed network result in a of 0.91% global energy efficiency increase.
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paper_title: Modelling and Experimental Study of the CO 2 Adsorption Behaviour of Polyaspartamide as an Adsorbent During Post-Combustion CO 2 Capture

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Abstract Adsorption technology due to its potentially low energy consumption, simple operation and flexibility in design to meet different demands is fast becoming popular and is now widely considered in the area of CO 2 capture. Adsorbents play a vital role in any adsorption technology. Therefore, the behavior of adsorbents under different conditions during an adsorption process needs to be investigated. In this study, the behavior of polyaspartamide as an adsorbent during post-combustion CO 2 capture was investigated using kinetic and non-kinetic models. Bohart-Adams and Thomas models were the non-kinetic models explored to ascertain whether external mass transfer dominated the overall system kinetics during the CO 2 adsorption onto polyaspartamide. The kinetics of adsorption of polyaspartamide was studied using Lagergen's pseudo 1 st order, Lagergen's pseudo 2 nd order and the Avrami kinetic models in order to understand whether the adsorption process was a physical, chemical or physiochemical process. The experimental validation of the model prediction was carried out in a laboratory-sized packed bed adsorption column at an operating pressure of 2 bar; gas flow rate of 1.5-2.5 ml/s, and a temperature range of 303-333 K using 0.1 g of the adsorbent. The experimental breakthrough curve showed a superior fit with the Bohart-Adams model. For the kinetic study, Avrami kinetic model displayed a better fit with kinetic data at all temperatures studied. The non-kinetic model revealed that external mass transfer governed the adsorption of CO 2 onto polyaspartamide while the kinetic study revealed that the mechanism of adsorption of CO 2 onto polyaspartamide was more of physical than chemical (physiochemical).
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paper_title: Framework for the Multiperiod Sequential Synthesis of Heat Exchanger Networks with Selection, Design, and Scheduling of Multiple Utilities

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A novel sequential approach is proposed for the multiperiod synthesis of Heat Exchanger Networks (HEN) and Utility Systems of chemical processes and energy systems. The framework can be used also for single period problems. Given the set of hot and cold process streams with period dependent heat loads and target temperatures and a set of available utility systems, the algorithm determines the optimal utility system selection, design, and operation scheduling, as well as the optimal HEN. In this work, the approach of solving multiperiod problems by adopting (1) the Multiperiod Utility Integration and Scheduling model of Marechal and Kalitventzeff, a modified formulation for (2) the Multiperiod Minimum Number of Units problem of Floudas and Grossmann, and (3) the Multiperiod Minimum Investment Network problem proposed by Floudas and Grossmann is improved by coupling the existing framework with the derivative-free hybrid algorithm PGS-COM of Martelli and Amaldi. Compared to the classic sequential approach,3 ...
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paper_title: Multi-period design of heat exchanger networks

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Abstract Heat exchanger networks are an integral part of chemical processes as they recover available heat and reduce utility consumption, thereby improving the overall economics of an industrial plant. This paper focuses on heat exchanger network design for multi-period operation wherein the operating conditions of a process may vary with time. A typical example is the hydrotreating process in petroleum refineries where the operators increase reactor temperature to compensate for catalyst deactivation. Superstructure based multi-period models for heat exchanger network design have been proposed previously employing deterministic optimisation algorithms, e.g. ( Aaltola, 2002 , Verheyen and Zhang, 2006 ). Stochastic optimisation algorithms have also been applied for the design of flexible heat exchanger networks recently ( Ma et al., 2007 , Ma et al., 2008 ). The present work develops an optimisation approach using simulated annealing for design of heat exchanger networks for multi-period operation. A comparison of the new optimisation approach with previous deterministic optimisation based design approaches is presented to illustrate the utilisation of simulated annealing in design of optimal heat exchanger network configurations for multi-period operation.
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paper_title: Design of heat exchanger network based on entransy theory

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Abstract The heat exchanger network (HEN) synthesis problem based on entransy theory is analyzed. According to the characteristics of entransy representation of thermal potential energy, the entransy dissipation represents the irreversibility of the heat transfer process, the temperature difference determines the entransy dissipation, and four HEN design steps based on entransy theory are put forward. The present study shows how it is possible to set energy targets based on entransy and achieve them with a network of heat exchangers by an example of heat exchanger network design for four streams. In order to verify the correctness of the heat exchanger networks design method based on entransy theory, the synthesis of the HEN for the diesel hydrogenation unit is studied. Using the heat exchange networks design method based on entransy theory, the HEN obtained is consistent with energy targets. The entransy transfer efficiency of HEN based on entransy theory is 92.29%, higher than the entransy transfer efficiency of the maximum heat recovery network based on pinch technology.
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paper_title: Synthesis of flexible heat exchanger networks: A review

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Abstract Dealing with uncertainty is one of practical issues in design and operation of heat exchanger networks (HENs), arising the problem of flexible HEN synthesis. This paper addresses the state-of-the-art methods for flexible HEN synthesis based on sensitivity analysis, resilience analysis, flexibility analysis and multiperiod synthesis techniques as well. Each of these methods is summarized by presenting their general procedures and recent developments on modeling, solving strategies and applications. Some current topics related to flexible process synthesis have been briefly presented to provide several future research possibilities.
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paper_title: The analysis of CO2 emission reduction using an ExSS model of Guangdong province in China

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This paper studied the CO2 emission scenarios of Guangdong province in 2020 and divided the CO2 emission increment and reductions into various departments and driving factors. Based on the Extended Snapshot model, two CO2 emission scenarios, Business as Usual (BaU) and Counter Measure (CM) scenario were constructed. CM scenario was completed by using reduction technical measures to achieve the reduction emission goal. The results showed that the amount of CO2 emission is less 189 million tonne in 2020 CM scenario than BaU scenario. By decomposing the emission reduction measures in CM scenario, it showed that the main means to reduce CO2 emissions were the industrial structure adjustment, the advanced energy efficiency and the power sector structure adjustment, and the emission reduction contribution rates were 36.85%, 34.55% and 21.74%, respectively. The analysis results could be recommended to the government to make the low-carbon development policy and path.
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paper_title: Process integration technology review: background and applications in the chemical process industry

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Process integration is a holistic approach to process design and operation which emphasizes the unity of the process. Process integration design tools have been developed over the past two decades to achieve process improvement, productivity enhancement, conservation in mass and energy resources, and reductions in the operating and capital costs of chemical processes. The primary applications of these integrated tools have focused on resource conservation, pollution prevention and energy management. Specifically, the past two decades have seen the development and/or application of process integration design tools for heat exchange networks (HENs), wastewater reduction and water conservation networks, mass exchange networks (MENs), heat- and energy-induced separation networks (HISENs and EISENs), waste interception networks (WINs) and heat- and energy-induced waste minimization networks (HIWAMINs and EIWAMINs), to name a few. This paper provides an overview of some of these developments and outlines major driving forces and hurdles. The fundamental aspects of this approach along with their incorporation in an overall design methodology will be discussed. The paper also highlights several recent applications of process integration to industrial processes.  2003 Society of Chemical Industry
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paper_title: Influence of Additives Including Amine and Hydroxyl Groups on Aqueous Ammonia Absorbent for CO2 Capture

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Aqueous ammonia absorbent (10 wt %) was modified with four kinds of additives (1 wt %) including amine and hydroxyl groups, i.e., 2-amino-2-methyl-1-propanol (AMP), 2-amino-2-methyl-1,3-propandiol (AMPD), 2-amino-2-ethyl-1,3-propandiol (AEPD), and tri(hydroxymethyl) aminomethane (THAM), for CO2 capture. The loss of ammonia by vaporization was reduced by additives, whereas the removal efficiency of CO2 was slightly improved. These results were attributed to the interactions between ammonia and additives or absorbents and CO2 via hydrogen bonding, as verified by FT-IR spectra and computational calculation. Molecular structures as well as binding energies were obtained from the geometries of (ammonia + additives) and (ammonia + additives + CO2) at the optimized state. These experimental and theoretical findings demonstrate that additives including amine and hydroxyl group are suitable for modifying aqueous ammonia absorbent for CO2 removal.
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paper_title: Design and analysis of biodiesel production from algae grown through carbon sequestration

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This paper addresses the design and techno-economic analysis of an integrated system for the production of biodiesel from algal oil produced via the sequestration of carbon dioxide from the flue gas of a power plant. The proposed system provides an efficient way to the reduction in greenhouse gas emissions and yields algae as a potential alternative to edible oils currently used for biodiesel production. Algae can be processed into algal oil by various pathways. The algal oil can then be used to produce biodiesel. A flowsheet of the integrated system is synthesized. Then, process simulation using ASPEN Plus is carried out to model a two-stage alkali catalyzed transesterification reaction for converting microalgal oil of Chlorella species to biodiesel. Cost estimation is carried out with the aid of ICARUS software. Further economic analysis is performed to determine profitability of the algal oil to biodiesel process. The results suggest that, for the algal oil to biodiesel process analyzed in this study, factors such as choosing the right algal species, using the appropriate pathway for converting algae to algal oil, selling the resulting biodiesel and glycerol at a favorable market selling prices, and attaining high levels of process integration can collectively render algal oil to be a competitive alternative to food-based plant oils.
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paper_title: Potential for energy savings by heat recovery in an integrated steel supply chain

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Abstract Heat recovery plays an important role in energy saving in the supply chain of steel products. Almost all high temperature outputs in the steel industry have their thermal energy exchanged to preheat inputs to the process. Despite the widespread development of heat recovery technologies within process stages (process heat recovery), larger savings may be obtained by using a wider integrated network of heat exchange across various processes along the supply chain (integrated heat recovery). Previous pinch analyses have been applied to optimise integrated heat recovery systems in steel plants, although a comparison between standard process heat recovery and integrated heat recovery has not yet been explored. In this paper, the potential for additional energy savings achieved by using integrated heat recovery is estimated for a typical integrated steel plant, using pinch analysis. Overall, process heat recovery saves approximately 1.8 GJ per tonne of hot rolled steel (GJ/t hrs), integrated heat recovery with conventional heat exchange could save 2.5 GJ/t hrs, and an alternative heat exchange that also recovers energy from hot steel could save 3.0 GJ/t hrs. In developing these networks, general heat recovery strategies are identified that may be applied more widely to all primary steel production to enhance heat recovery. Limited additional savings may be obtained from the integration of the steel supply chain with other industries.
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paper_title: Planning of carbon capture and storage with pinch analysis techniques

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Carbon capture and storage (CCS) is a means for reducing carbon dioxide (CO2) emissions from fossil fuel combustion in power generation and industrial processes. It involves the capture of CO2 for subsequent storage in various geological formations. The selection and matching of the power plants and storage sites are often an issue of optimisation due to various constraints, i.e., time of availability, injection rate, and storage capacity limits. In this work, a novel graphical targeting tool based on pinch analysis is proposed to address the planning problem of the storage of captured CO2 from power generating plants into corresponding reservoirs. The main consideration for the problem is the time of availability of the latter, since reservoirs need to be developed prior to CO2 storage. The time limitation is addressed by the graphical technique where time is taken as the governing element in solving the problem. Hypothetical examples are used to elucidate the proposed approach.
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paper_title: Process Integration of Low Grade Heat in Process Industry with District Heating Networks

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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.
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paper_title: A new graphical approach for simultaneous mass and energy minimisation

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Heat and mass such as water and solvents are two key utilities in process industry. Simultaneous reduction of both utilities can reduce plant capital as well as operating costs. Though there are mathematical modeling techniques that can produce global optimal solutions, graphical methods are often preferred to provide insights through visualization. This paper presents a new graphical approach named superimposed mass and energy curves (SMEC) for simultaneous mass and heat reduction applicable to both mass transfer-based and non-mass transfer-based systems. Source and demand allocation curves and heat surplus diagram are superimposed on a plot of flowrate versus mass load/temperature to guide design towards the minimum utility targets. This method provides a useful visualization tool on the simultaneous effects of mass and energy reduction. Application of the graphical procedure on case studies involving water and ammonia solvents achieved the minimum mass consumption and near optimal energy usage.
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paper_title: Heat, mass, and work exchange networks

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Heat (energy), water (mass), and work (pressure) are the most fundamental utilities for operation units in chemical plants. To reduce energy consumption and diminish environment hazards, various integration methods have been developed. The application of heat exchange networks (HENs), mass exchange networks (MENs), water allocation heat exchange networks (WAHENs) and work exchange networks (WENs) have resulted in the significant saving of energy and water. This review presents the main works related to each network. The similarities and differences of these networks are also discussed. Through comparing and discussing these different networks, this review inspires researchers to propose more efficient and convenient methods for the design of existing exchange networks and even new types of networks including multi-objective networks for the system integration in order to enhance the optimization and controllability of processes.
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paper_title: Systematic Synthesis of Mass Exchange Networks for Multicomponent Systems

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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, environmental, and economic requirements. Most of the MEN research has focused on single-component problems. Much less attention has been given to the multicomponent problem. Therefore, the aim of this paper is to develop a systematic method to deal with the multicomponent MEN synthesis problem. The concept of interception is introduced to account for compatible mass transfer of the multiple components in a way that can be practically realized in mass exchange units. A mixed-integer nonlinear programming (MINLP) model is established to embed potential configurations of interest. Linearization, disjunctive programming, and relaxation are used to enhance the solvability of the optimization program, which is aimed at minimizing the total annualized cost (TAC) of the MEN. Two case studies from the literature, the recovery of copper from an etching plant and the simultaneous removal of H₂S and CO₂ from coke-oven gas (COG), are solved to illustrate the application of the proposed method.
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paper_title: Process intensification and integration of solar heat generation in the Chinese condiment sector - A case study of a medium sized Beijing based factory

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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.
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paper_title: Process Intensification and Integration: an assessment

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A considerable number of studies have been performed for improving the efficiency of production processes, of energy supply and utilisation, while reducing emissions of greenhouse gases, volatile organic compounds and other pollutants. This has been a very important task which this journal has been targeting. As a response to these industrial and societal requirements considerable research effort has been targeted to process integration and process intensification. This article has made an attempt for a short assessment of those advanced engineering approaches.
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paper_title: Oxy-combustion power plant integration in an oil refinery to reduce CO2 emissions

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Abstract The refining sector comprises a lot of different processes, since a wide range of final products are obtained in refineries. In any case, CO 2 emissions levels are high and three units can be considered as the main sources accounting the majority of carbon dioxide emissions to the atmosphere: the utility boilers system, the process heaters and the fluid catalytic cracking unit (FCC). In this study, the substitution of the utility boilers system for an oxy-combustion power plant is presented. The power plant is designed to cover the steam thermal and electricity demands of oil refinery. In addition, a heat integration methodology based on pinch analysis is applied to the whole concept for increasing efficiency. Final results show that more than 380,000 tonnes of CO 2 could be avoided. Afterwards, a complete economic approach is carried out. Although profitability is still low with current economic costs, it is expected that in the medium term, oxy-combustion could be economically feasible in refining sector. To this extent, sensitivity analysis shows affordable values for main economic parameters that can be reached in the next years. A 24 €/MWh natural gas price reduces operational cost for oxy-combustion power plant below the conventional refinery value. An electricity price higher than 67 €/MWh and a CO 2 cost around 20 €/tCO 2 also seem to reduce operational cost below reference case ones. The study concludes with the analysis of some realistic future scenarios that prove the oxy-combustion technology both technically and economically feasible and payback periods between 9 and 11 years with IRR values around 7% can be affordable within the following years.
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paper_title: A systematic approach for high temperature looping cycles integration

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High temperature solid cycles are promising technologies for implementing large-scale CO2 capture facilities in the mid-term. Energy integration plays a major role in the development of these cycles. Waste energy from the capture process may be used to retrofit an existing power plant or to power a new steam cycle, thus diminishing the energy penalty that the process entails. A procedure based on pinch analysis for the integration of these systems, is proposed and tested using limestone as CO2 sorbent. Although Li4SiO4 has been already dismissed for this purpose, it is used to validate the systematic procedure under a very different problem in terms of available heat and initial temperatures of hot streams. In both scenarios the integration was designed to take advantage of all available heat of the process and to power a supercritical steam cycle, quantifying their minimum energy penalty. A sensitivity analysis for each process was also developed, and the heat exchanger network achieved by the proposed algorithm obtained the best results in costs terms.
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paper_title: Minimisation of a heat exchanger networks' cost over its lifetime

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The optimal design of heat exchanger networks (HENs) has a great influence on the profitability of a plant. The optimisation is based on trade-offs between investment and operational cost. The full lifetime of the HEN and future utility prices have to be considered rather than optimising HEN on a yearly basis using current utility prices. Single-period optimisation and synthesis models for HENs reflect current utility prices only. These prices can fluctuate rather quickly and the optimal solution may be very different from a year to year. Deterministic and stochastic multi-period mixed-integer nonlinear programming (MINLP) models for HEN synthesis have been developed to account for future price projections, where the utility cost coefficients are forecasted for the lifetime of the process. An optimal design is then determined for each projection and these designs are compared against a design with fixed current prices by applying the Incremental Net Present Value and other economic measures. In case studies the difference between utility consumption, using previous optimisation methods and new, were significant; e.g. in Case Study 2 the utility savings were 18.4% for hot and 32.6% for cold utility yielding an increase of the Net Present Value (NPV) by 7.8%.
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paper_title: Reduction of greenhouse gas emissions by integration of cement plants, power plants, and CO2 capture systems

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Cement plants and power plants are two of the most significant sources of greenhouse gases emissions. Many CO 2 reduction options have been proposed in literature for both sectors. They are mainly focused on CO 2 capture in power plants, but, in the short‐term, industrial processes are going to play an important role in achieving this objective. In particular, one of the disadvantages in cement plants is that CO 2 has two sources: fuel combustion and lime calcination. For this reason, proposed solutions could partially reduce a limited quantity of emissions. The sector is forced to use CO 2 capture systems for further reductions. Preliminary results about the implementation of post‐combustion and oxyfuel combustion systems for CO 2 capture show low energetic penalties and important emissions reduction. Nevertheless, a detailed analysis, not only of CO 2 emissions, but of raw materials and its disposal, primary energy and waste energy, could give optimum results from an environmental, energetic, and economic perspective. The combination/integration by industrial symbiosis of a power plant, a cement plant and a CO 2 capture system is proposed in this work. Calcium‐looping is chosen as the most suitable CO 2 capture option for this application. The re‐use of waste CaO coming from CO 2 capture in the cement plant, and the utilization of waste energy from a clinker cooling and capture system to produce additional power are the main advantages of this proposal. Process flow diagrams and heat and mass balances are calculated and presented in this work. Results show a low value of the CO 2 avoided cost, 12.4 €/t, that is smaller than in any other combination of power plant with capture system or cement plant plus capture system, making this proposal economically very attractive. Moreover, an important amount of CO 2 emissions is avoided ‐ 94% ‐ due to the energetic efficiency augmentation, the reduction of raw and decarbonizated materials, and the CO 2 capture system. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
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paper_title: Process Integration techniques for optimal design of hybrid power systems

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Abstract Power Pinch Analysis (PoPA) is a technique for the optimal power allocation in hybrid systems comprising of renewable energy sources. The graphical PoPA tools have recently been proposed to determine targets for the minimum amount of outsourced electricity and the maximum amount of excess electricity to be stored and reused in the hybrid power systems. The numerical techniques for PoPA have so far not been developed. This work introduces two new PoPA numerical tools known as the Power Cascade Analysis (PoCA) and the Storage Cascade Table (SCT). The tools can be used to determine (1) the minimum target for outsourced electricity, (2) the amount of excess electricity for storage during start up and normal operations, (3) the amount of transferrable power, (4) the maximum storage (e.g. battery) capacity for the off-grid systems, (5) the amount of electricity transferrable to the grid, (6) the amount of outsourced electricity needed at each time interval and (7) the time interval where the maximum power demand occurs. While the graphical techniques provide useful visualisation insights, the numerical tools enable more rapid and precise allocation of power as well as the determination of electricity targets.
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paper_title: Potential for energy savings by heat recovery in an integrated steel supply chain

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Abstract Heat recovery plays an important role in energy saving in the supply chain of steel products. Almost all high temperature outputs in the steel industry have their thermal energy exchanged to preheat inputs to the process. Despite the widespread development of heat recovery technologies within process stages (process heat recovery), larger savings may be obtained by using a wider integrated network of heat exchange across various processes along the supply chain (integrated heat recovery). Previous pinch analyses have been applied to optimise integrated heat recovery systems in steel plants, although a comparison between standard process heat recovery and integrated heat recovery has not yet been explored. In this paper, the potential for additional energy savings achieved by using integrated heat recovery is estimated for a typical integrated steel plant, using pinch analysis. Overall, process heat recovery saves approximately 1.8 GJ per tonne of hot rolled steel (GJ/t hrs), integrated heat recovery with conventional heat exchange could save 2.5 GJ/t hrs, and an alternative heat exchange that also recovers energy from hot steel could save 3.0 GJ/t hrs. In developing these networks, general heat recovery strategies are identified that may be applied more widely to all primary steel production to enhance heat recovery. Limited additional savings may be obtained from the integration of the steel supply chain with other industries.
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paper_title: Synthesis of mass exchange networks

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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.
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paper_title: Pinch analysis approach to carbon-constrained energy sector planning

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Pinch analysis techniques have been developed for a wide range of applications ranging from process plant thermal or water integration to financial and supply chain management. This paper presents a new application of pinch analysis. A scenario is assumed wherein energy sector planning takes place with carbon emission constraints arising from an effort to reduce climate change effects. A procedure for identifying the minimum amount of zero-carbon energy resource required to achieve the overall emissions target for a country or region, given that the amount of fossil energy resources available are already known. The pinch analysis method can be used for a single overall emissions target, or for cases wherein separate sectors or geographic regions have distinct targets but share a common energy resource. For the latter case the procedure allows the allocation of the energy resources to meet both the overall emissions limit and the individual targets of the different sectors or location. Numerical examples are provided to illustrate the technique, which is intended for use as a preliminary energy sector-planning tool.
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paper_title: Incorporating Timesharing Scheme in Ecoindustrial Multiperiod Chilled and Cooling Water Network Design

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Chilled/cooling water is a common utility widely used in office or commercial buildings for air conditioning. It is also used in various industries such as semiconductor fabrication and the food industries for process cooling. Previous studies focused on the synthesis of chilled/cooling water networks within individual plants. The establishment of an ecoindustrial park (EIP) that originates from the concept of industrial symbiosis allows individual plants to cooperate with each other so as to achieve greater water and energy recovery through interplant chilled/cooling water reuse/recycle. However, periodical circumstances such as variation of market demands and plant shutdown schedules, which are common in different business operations, have not been well considered in designing an EIP. Thus, there is a need to study explicitly the effect of such periodical operations due to the high level of connectivity within an EIP. This paper presents a design methodology to develop a robust EIP by integrating a set ...
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paper_title: A comprehensive review on energy efficient CO2 breakthrough technologies for sustainable green iron and steel manufacturing

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Iron and steel industry is the largest energy consuming manufacturing sector in the world. It is responsible for emitting 4–5% of the total anthropogenic CO2. Due to consistently increasing demand of iron and steel products for human needs, fossil-fuel energy use and CO2 emission will continue to grow in this industry. So there is a strong motivation to develop and implement energy-efficient and low-carbon technologies as well as carbon reduction programs for this industry. Enhancing the development and deployment of high-temperature waste heat energy recovering technologies along a desired combination of carbon capture and storage (CCS) technologies will be the effective solution to reducing CO2 emissions from iron and steel production. The aim of this paper is to provide a comprehensive overview of the worldwide carbon reduction programs and new CO2 breakthrough technologies for energy saving and carbon capture and storage in iron and steel making processes by collating updated information from a wide range of sources. Also, a discussion on the selection of the appropriate technology and their barriers and stages of development and deployment is presented. It is found that lots of factors that limit the role of using biomass in CO2 abatement, so implementation of CCS technology in coal-based integrated steel plant would be an efficient means for sustainable green iron and steel manufacturing.
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paper_title: Cost-effective Strategy for Heat Exchanger Network Retrofit

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Abstract Cost-effective retrofit of heat exchanger networks (HENs) remains a significant challenge. This paper explores different methods for achieving cost-effective retrofit. The first part of this article presents a novel methodology for the application of heat transfer enhancement in HEN retrofit with a fixed network structure considering pressure drop constraints. Heat transfer enhancement is a low-cost option. However, heat transfer enhancement on its own without changes to the network structure provides a limited scope for energy reduction. The second part of this paper presents a new pinch retrofit method that identifies network structural changes sequentially to meet the retrofit target. However, the high capital cost associated with installing new heat exchangers, relocating existing exchangers, and augmenting the heat transfer area of existing heat exchangers most often leads to uneconomic retrofits. Low-cost retrofit requires few modifications. Therefore, the third part of this paper combines the new pinch retrofit method with the use of heat transfer enhancement to provide low-cost retrofit by combining the merits of both approaches. A case study highlights the benefits of the new approach.
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paper_title: Design of Heat Storage Units for use in repeatable Time Slices

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Abstract This paper suggests a new approach to design of heat storage units. The designed Heat Storage Units (HSU) should be used in repeatable processes for different Time Slices (TS) with the same pair of previously heat integrated process streams. The design of Heat Storage Units (HSU) is based on analysis of heat cascades calculated for heat process integration of selected streams with Pinch Table Algorithm (PTA). Determined surplus heat loads, the temperature difference of storage material and the physical characteristics of heat storage material were used for computation of construction characteristics and estimated cost for Heat Storage Units (HSU). Two different approaches were used, heat storage process depends on industrial process parameters related to Pinch technology as well as determination of optimal volume for heat storage design on total cost for investing in such units. The designed Heat Storage system related to Pinch technology gave different compared to the approach with minimization of total estimated costs. The final selections of Heat Storage Unit design was determined with satisfying of Pinch Technology rules. The previously analyzed case study for heat process integration of Baker‘s yeast and ethyl alcohol production plant were referent system for upgrading for Heat Storage system. The cost estimation of designed Heat Storage Units (on both proposed ways) was made, and it was compared with estimated prices for hot and cold utility that would be replaced with Heat Storage for the whole annual cycle. In this case study low profitability was found because of small heat load within Heat Storage accumulation. Systems that would accumulate much more heat energy would give profitable investment.
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paper_title: Capital and total cost targets for mass exchange networks: Part 1: Simple capital cost models

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Abstract This part of the paper builds on the developments of Part 1. It starts by developing a targeting method for tray columns using detailed capital costing methods. The number of units, column diameters and tray spacings, and the distribution of units and trays will all be considered. The limitations of stages targeting are also discussed, leading to an explanation of why stages targets may be beaten, and showing how continuous contactors are more analogous to heat exchangers than stagewise contactors. A procedure for determining capital cost targets for networks of continuous contactors (usually packed columns) is then developed. Networks featuring different exchanger specifications are also dealt with. As before, capital cost targets are combined with operating cost targets to give total annual cost targets. The design of networks to meet the targets is then discussed. Systems featuring significant differences in exchanger specifications may require some deviation from ideal (vertical) driving force use. The examples presented in this part of the paper demonstrate that the targets are accurate enough for preliminary design as well as pre-design optimisation. The work in both parts of this paper reduces the amount of design work required when evaluating processes at the conceptual stage.
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paper_title: Systematic Synthesis of Mass Exchange Networks for Multicomponent Systems

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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, environmental, and economic requirements. Most of the MEN research has focused on single-component problems. Much less attention has been given to the multicomponent problem. Therefore, the aim of this paper is to develop a systematic method to deal with the multicomponent MEN synthesis problem. The concept of interception is introduced to account for compatible mass transfer of the multiple components in a way that can be practically realized in mass exchange units. A mixed-integer nonlinear programming (MINLP) model is established to embed potential configurations of interest. Linearization, disjunctive programming, and relaxation are used to enhance the solvability of the optimization program, which is aimed at minimizing the total annualized cost (TAC) of the MEN. Two case studies from the literature, the recovery of copper from an etching plant and the simultaneous removal of H₂S and CO₂ from coke-oven gas (COG), are solved to illustrate the application of the proposed method.
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paper_title: Comparison of different mathematical programming techniques for mass exchange network synthesis

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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.
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paper_title: Optimum energy integration of thermal hydrolysis through pinch analysis

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Anaerobic digestion, a well-established technology to generate biogas from sewage sludge, is constrained by the hydrolysis (or solubilization) stage. Several pretreatments attempt to overcome this limitation, with thermal hydrolysis emerging as the technology of choice due to its techno-economic advantages. The objective of this work is to optimize the integration of this energy intensive pretreatment within the wastewater treatment plant, ensuring that the digestion performance improves in an energy-efficient way. By applying pinch analysis, a methodology to optimize energy systems, a strategy is suggested that selects a second-generation thermal hydrolysis technology designed to recover all process vapors, defines the optimum combined heat and power scheme to ensure an efficient integration and determines the minimum sludge feed concentration to guarantee energy self-sufficiency, the recovery of all waste heat and the minimization of expensive polyelectrolyte use.
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paper_title: State-of-the-art review of targeting and design methodologies for hydrogen network synthesis

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Abstract The synthesis of hydrogen distribution networks has been an active area of research over the last two decades. The concept of hydrogen management based on an economic cost-driven analysis appeared late in the 1990s and was followed up by numerous insight-based and mathematical optimisation approaches in the 2000s. More recently, several superstructure-based optimisation methods have been proposed to accommodate pressure restrictions, additional equipment and other practical constraints when finding the optimal flowsheet configuration. This paper provides a state-of-the-art review of different process integration technologies adopted for the assessment of hydrogen resources in refineries and petrochemical plants, published from late in the 1990s to the present time. Both targeting and design methods are reviewed. An effective hydrogen management strategy can only be achieved by combining different insight-based approaches with detailed mathematical programming.
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paper_title: A pinch analysis approach to project selection problem

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Project selection is a very important decision that every firm has to take; in fact, this decision plays a major role in the prosperity of the firm. Pinch analysis, which was initially developed to conserve energy and improve energy efficiency in industrial process, is now being extended to non-conventional areas. In this paper, pinch analysis is applied to select multiple independent projects from a large pool of viable projects, subject to budget constraints. The underlying mathematical optimization problem is discussed and a graphical approach to obtain optimal insightful solutions is presented. Applicability of the proposed methodology is demonstrated through an illustrative example of energy conservation in the Indian cement industry.
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paper_title: Application of an advanced pinch methodology for the food and drink production

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Two key steps in reducing the energy demand of a production site are (1) technological optimization via efficient technologies increasing process efficiency and (2) system optimization via heat integration of the total production site. Heat integration solutions will be influenced by the implemented process technologies, so the evaluation of the existing technologies and analysis of potential changes is a vital basis in energy demand reduction. This article presents the new pinch analysis tool ‘SOCO’ for systematic heat integration with intelligent storage systems which can reduce thermal energy consumption and improve the design of solar process heat integration in the food industry, specifically in breweries. The application to two brewery case studies reveals the usability of the new approach for designing new heat recovery concepts and the implications of technology changes in the energy demand profile. The simulation module of SOCO identifies that the use of modern state-of-the-art technologies in brewing can enhance heat integration potential by 10–35% for different processes and allows the evaluation of storage design. WIREs Energy Environ 2014, 3:561–574. doi: 10.1002/wene.117 ::: ::: For further resources related to this article, please visit the WIREs website. ::: ::: Conflict of interest: The author has declared no conflicts of interest for this article.
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paper_title: 5 Scope for the Application of Mathematical Programming Techniques in the Synthesis and Planning of Sustainable Processes

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Sustainability has recently emerged as a key issue in process systems engineering (PSE). Mathematical programming techniques offer a general modeling framework for including environmental concerns in the synthesis and planning of chemical processes. In this paper, we review major contributions in process synthesis and supply chain management, highlighting the main optimization approaches that are available, including the handling of uncertainty and the multi-objective optimization of economic and environmental objectives. Finally, we discuss challenges and opportunities identified in the area.
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paper_title: Selection of energy conservation projects through Financial Pinch Analysis

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Energy conservation measures are an important means of reducing operating costs and greenhouse emissions. However, one of the barriers to the implementation of such projects is the limited availability of financial resources. Pinch Analysis, which was initially developed to conserve thermal energy and improve energy efficiency in industrial processes, is extended in this paper to address the problem of energy conservation project selection. A new method is developed to include financial cash flows for appropriate selection among independent projects. This study applies Financial Pinch Analysis to select multiple independent projects from a large pool of candidate projects, subject to different funding constraints. To account for the time value of money, Net Present Value is used to determine the financial feasibility of the projects against various funding options. The applicability of the proposed method considers a pool of projects with equal and unequal lives, as well as the financial risk associated with individual projects. In this study, risk is estimated by calculating the certainty equivalent cash flows of the projects. A graphical approach to obtain optimal insightful solutions is presented and demonstrated through three illustrative examples of energy conservation projects in the pulp and paper and cement industries.
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paper_title: Utility Exchanger Network Synthesis for Total Site Heat Integration

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Abstract Total Site Heat Integration (TSHI) targeting and optimisation methods have been well developed while few studies deal with detailed Utility Exchanger Network (UEN) design. The UEN is the network of heat exchangers that connect a site’s centralised utility system to provide the required process heating and cooling while also facilitating inter-process heat recovery, i.e. TSHI. This paper presents a new UEN design procedure based on the recently developed Unified TSHI targeting method. The Unified method applies more strict constraints on the UEN network, compared to Conventional methods, allowing series utility exchanger matches for a non-isothermal utility if the exchangers in series are from the same process. This constraint reduces the dependency of the individual processes that constitute the Total Site. In UEN design procedure based on the Unified method, calculated utility targets can be archived after UEN design and the number of exchangers reduces compared to the Conventional methods’ design procedure. Also, different Exchanger Minimum Approach Temperature in the UEN synthesis may have an influence on network design and the exchanger configuration but the identical heat recovery and utility targets are achieved after UEN design based on both design procedures.
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paper_title: Forty years of Heat Integration: Pinch Analysis (PA) and Mathematical Programming (MP)

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Process Integration (PI) supporting Process Design, Integration, and Optimisation has been around from the early 1970s. PI was developed originally from Heat Integration, which remains the cornerstone for PI continuous advance. It has been closely related to the development of Chemical, Mechanical and Power Engineering supported by the extended implementation of mathematical modelling, simulation and optimisation, and by the application of information technology. Its development has accelerated over the years as its methodology has been able to provide answers and support for important issues regarding economic development — better utilisation and savings regarding energy, water, and other resources. This contribution is targeting towards providing at least a short overview of its historical development, achievements, and future challenges.
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paper_title: Synthesis of Heat Exchanger Networks Taking into Account Cost and Dynamic Considerations

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Abstract In this work an approach is presented for the synthesis of near cost optimal heat exchanger networks with a high controllability. The presented methodology is based on a sequential approach utilizing different algorithms and mathematical models. The procedure is carried out in three steps. A genetic algorithm is used to produce a high diversity of promising structures that suffice the needs for cost reduction and controllability characteristics. For selected structures controllability evaluations are carried out, which are mainly based on relative gain array and condition number assessments. Therefore, a linear model is utilized which was further used to calculate the area adjustments and nominal bypasses for complete disturbance rejection for perfect control. As a last step simplified mathematical solution models are used to further extend insight gained for decision-making. These models are used to carry out dynamic simulations for testing the impact of different possible decentralized feedback control structure designs developed by previous methods. The application of the developed approach will be shown using an example from literature.
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paper_title: Cost optimal energy sector planning: a Pinch Analysis approach

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Abstract Renewable energy sources can contribute to the increasing energy demand as well as reduction of green-house gas emissions and pollutants. It is desirable to find the optimum mix between renewable and non-renewable energy sources, based on carbon emissions or cost of electricity constraints. In this paper, a Pinch Analysis based method for allocating different energy sources to different demands of a region is proposed. The proposed approach determines the cost optimum mix of various energy sources. Applicability of the method is demonstrated through an illustrative case study of Lakshadweep Islands, India. These islands are too remote to have inter-connections with the mainland and depend on imports of oil for electrical, process, and transport energy requirements. The locally available renewable energy sources can be used to solve problems of energy security, higher energy cost, and environmental pollution. Additionally, the Government of India provides a significant amount of subsidy to supply electricity in Lakshadweep Islands. The proposed method helps in reducing the burden of subsidy significantly by appropriately utilizing locally available renewable energy sources. The proposed Pinch Analysis formulation consider energy as flow, cost of energy as quality, and minimizes subsidized diesel based power generation (formulated as resource). Based on the current acceptable price of electricity, the use of renewable energy sources leads to saving in the subsidy of 317.08 × 10 6 Rs./y and reduction in emissions from diesel generator set by about 58%. The policy implications for subsidy are also discussed in this paper and therefore, the work is useful to guide policy makers.
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paper_title: Pinch analysis-based approach to industrial safety risk and environmental management

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Pinch Analysis is an established method for enhancing the sustainability of industrial processes via efficient use of various resources. It is based on the principle of target identification followed by subsequent system design aided by a problem decomposition strategy based on the Pinch Point. This approach has recently been extended to apply to a broad range of structurally analogous problems in various domains, such as financial management and carbon-constrained energy planning. In this work, a novel graphical methodology for industrial safety risk and environmental management is proposed. In this method, it is assumed that a set of risk or pollution reduction measures is available, and that each measure is characterized by its implementation cost and the degree of benefit that it delivers. These data are then used to generate a source composite curve. Targeting can then be achieved by shifting this curve relative to a pre-defined sink composite curve, which represents the locus of the plant management’s “willingness to pay,” or budget relative to benefits with respect to risk or pollutant reduction. The methodology is then demonstrated on two case studies. The first case is based on the well-known Bhopal incident, while the second case focuses on the reduction of airborne fluoride emissions from brick firing plant.
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paper_title: A new paradigm in process synthesis focus on design of power plants and industrial processes integrated with CO2 capture

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Abstract Process synthesis methods have only recently been applied for the design of CO 2 capture systems. At the crux of the CO 2 capture process is a separation technology (sorbent, membrane or phase separation) applied to CO 2 /N 2 , CO 2 /H 2 or O 2 /N 2 systems. Development of novel sorbents and membranes have been identified to be an important area of research to realize cost-competitive CO 2 capture technologies. Thus, there are different capture technologies at varying levels of maturity that need to be integrated with the power plant or industrial process. Traditional optimization based approaches to process synthesis of CO 2 capture systems, while important for mature process components, have a lesser role to play in this application wheer components are still in a constant state of development. Due to the multidisciplinary nature of CO 2 capture, integrating other sciences such as process chemistry with process synthesis should be emphasized. This work will present novel approaches to process synthesis that represent a new paradigm in process synthesis. The focus of process synthesis is modified from identifying an “optimum” process, to using the framework of the discipline to provide feedback on optimum operating parameters/conditions of the novel separation processes. Motivation for visual and hybrid methodologies based on attainable region approach as opposed to the more common optimization based methods are presented.
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paper_title: Maximising heat recovery in batch processes via product streams storage and shifting

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In a batch process, either direct or indirect heat integration may be employed. The former involves direct heat transfer from hot to cold process streams. In the latter, heat from a hot process stream is first transferred to an intermediate fluid where the heat is stored until it is finally transferred to a cold stream. Storage of product streams allows direct heat integration to be delayed, thereby providing an opportunity for energy conservation while avoiding the use of an intermediate fluid. This paper presents a new methodology for batch heat integration that involves the direct storage of product streams within the procedure to set the minimum utility targets. Application of the proposed methodology on illustrative examples demonstrates that significant energy reduction can be achieved by shifting product streams on the time scale. Potential reductions of 33.2% cold utility and 45.1% hot utility were estimated for the first example when the product stream was stored. Similarly, reductions of 3.5% cold utility and 6.5% hot utility were observed for a two-product batch plant when the cooling requirement for one of the products was shifted on time scale.
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paper_title: Minimizing carbon footprint using pinch analysis: The case of regional renewable electricity planning in China

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Renewable energy has a more important role to play in China’s power sector, especially at the regional level. Renewable electricity in China has made great progress on the basis of national policies. However, the promotion of renewable electricity sector at the regional level is still hampered by local issues. China needs to solve some challenging barriers related to implementation of polices for the development of renewable electricity. These barriers stem largely from availability and reliability constraints. Systematic planning techniques are needed to fully utilize abundant renewable energy resources. In this work, an improved graphical pinch analysis-based approach is presented, which considers carbon-constrained regional electricity planning and supply chain synthesis of biomass energy at the regional level in rural China. The minimum renewable energy target is identified by Carbon Emissions Pinch Analysis (CEPA). Next, a demand-driven approach is applied to synthesize the biomass supply chain network to meet the established target in a given region. A detailed case study of Laixi County in China is used to demonstrate the applicability of the proposed approach for policy-making to promote utilization of renewable electricity at the regional level.
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paper_title: Simultaneous synthesis of heat exchanger network with the non-isothermal mixing

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Optimization of heat exchanger network is attributed to improving the process industrial energy utilization ratio. Energy consumption reduction plays an important role in the low-carbon economic development. Several synthesis approaches for heat exchanger network have been proposed and extended during the last three decades. With the evolution of the computer technology, the simultaneous synthesis method via mathematic programming attracts a great deal of attention worldwide. However, some difficulties still need to be overcome, for instance, model simplification and computational complexity. In this work, the simultaneous stage-wise synthesis model without the assumption of isothermal mixing is presented and implemented using effective initialization strategies and a novel two-level algorithm. Three case studies illustrated the better performance of the initialization strategies and two-level algorithm for heat exchanger network synthesis problems, considering non-isothermal mixing.
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paper_title: Synthesis of heat exchanger networks using mathematical programming and heuristics in a two-step optimisation procedure with detailed exchanger design

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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.
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paper_title: Unified pinch approach for targeting of carbon capture and storage (CCS) systems with multiple time periods and regions

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Carbon capture and storage (CCS) is a key technology for the mitigation of industrial carbon dioxide (CO2) emissions. It involves the reduction of emissions from large industrial facilities (i.e., sources) by capturing the CO2 from the exhaust gases and subsequently storing it in appropriate geological storage sites (i.e., sinks) such as depleted oil and/or gas reservoirs, saline aquifers, coal seams and other similar formations. In practice, these sites may not be readily available for storage at the same time or before the sources are operating, which gives rise to a temporal aspect in the planning problem. At the same time, sources and sinks may need to be clustered geographically to minimize the need to transport CO2 over long distances. This work presents an improved pinch analysis based methodology by simultaneously considering injectivity constraint of every sink as well as time of availability of various sources and sinks. Three illustrative case studies are used to demonstrate the applicability of the proposed methodology. The first two case studies illustrate graphical and algebraic variants, while the third case studies shows an extension that involves two distinct geographical regions.
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paper_title: The energy penalty of post-combustion CO2 capture & storage and its implications for retrofitting the U.S. installed base

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A review of the literature has found a factor of 4 spread in the estimated values of the energy penalty for post-combustion capture and storage of CO2 from pulverized-coal (PC) fired power plants. We elucidate the cause of that spread by deriving an analytic relationship for the energy penalty from thermodynamic principles and by identifying which variables are most difficult to constrain. We define the energy penalty for CCS to be the fraction of fuel that must be dedicated to CCS for a fixed quantity of work output. That penalty can manifest itself as either the additional fuel required to maintain a power plant's output or the loss of output for a constant fuel input. Of the 17 parameters that constitute the energy penalty, only the fraction of available waste heat that is recovered for use and the 2nd-law separation efficiency are poorly constrained. We provide an absolute lower bound for the energy penalty of ∼11%, and we demonstrate to what degree increasing the fraction of available-waste-heat recovery can reduce the energy penalty from the higher values reported. It is further argued that an energy penalty of ∼40% will be easily achieved while one of ∼29% represents a decent target value. Furthermore, we analyze the distribution of PC plants in the U.S. and calculate a distribution for the additional fuel required to operate all these plants with CO2 capture and storage (CCS).
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paper_title: HEN optimization for efficient retrofitting of coal-fired power plants with post-combustion carbon capture

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Abstract This study aims at reducing the energy penalty burdened by integration of pulverized coal-fired power plants with solvent-based post-combustion carbon capture (PCC) processes via heat exchanger network (HEN) optimization. The base case used is a 300 MWe coal-fired power plant burning pulverized black coal and emitting 256 tonnes/h of CO 2 . Integration of the base case with PCC showed that achieving 90% CO 2 capture with purity of 99% using 30 wt% monoethanolamine (MEA) solvent admits an energy penalty of 19.4% to the overall plant output. Pinch analysis showed that a reduction in the mentioned energy penalty down to 15.9% can be achieved via integration.
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paper_title: Minimization of CO2 capture energy penalty in second generation oxy-fuel power plants

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Abstract Oxy-combustion is one of the most promising technologies to reduce CO2 emissions from coal-fired power plants. Nevertheless, as CO2 capture system there is an important energy penalty and efficiency of the overall power plant substantially decreases. It is well accepted that the application of first generation post-combustion and oxy-fuel combustion technologies reduce the power plant efficiency in 10–12 efficiency points. Air separation unit (ASU) and compression and purification unit (CPU) are the main energy consumers in the oxy-fuel process. Moreover, the oxidant flow, which is a mixture of O2 and recirculated flue gases (RFG), requires a high heating demand in order to preheat it before the boiler inlet. This paper presents a methodology for the minimization of the energy penalty in oxy-fuel power plants that also includes ASU and CPU optimized designs with lower energy consumption, a boiler working with a high oxygen concentration (up to 40%v) in oxidant and waste energy integrated with a new designed steam cycle. Results show an important increase in power plant net efficiency (36.42%, LHV basis) regarding oxy-fuel reference power plant (32.91%). As a consequence, energy penalty can be reduced from original 10.5 points to 7.3 points.
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paper_title: Energy analysis of the cryogenic CO 2 capture process based on Stirling coolers

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In the existing coal-fired power plants, the energy penalty associated with CO2 capture process is an important challenge. For this reason, energy analysis has been widely used as a powerful tool to optimize the capture efficiency and reduce energy consumption. In our previous work, a Stirling cooler based cryogenic CO2 capture system was outlined. Process simulation and energy analysis of the system were undertaken in this research. The whole CO2 capture process is composed of three sections: pre-chilling, CO2 anti-sublimation and storage. The energy consumption of each section in the system was investigated in detail. The results show that when the flow rate of flue gas (13vol.% CO2) is set at 5L/min and the temperature of Stirling cooler-1, 2 and 3 is set at −30, −120 and −120°C, respectively, the energy consumption of the pre-chilling, CO2 anti-sublimation and storage sections are 15.58thermalJ/s, 30.48thermalJ/s and 11.40thermalJ/s, respectively. The total energy consumption of the cryogenic CO2 capture system is 57.46thermalJ/s (equal to 689.52J/L flue gas).
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paper_title: Low Carbon Technologies (LCT) and Carbon Capture & Sequestration (CCS)—Key to Green Power Mission for Energy Security and Environmental Sustainability

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Despite the fact that India has taken a giant leap forward in increasing the installed capacity from a mere 1367 MW in beginning of Independence era to over 303,100 MWe in June 2016, the renewable energy sources however contribute merely 14.1% with total capacity of over 42,800 MW. But this contribution has a major social and economic impact on rural and remote area population. The growth of clean energy technologies for mega Power generation, such as the Solar Mega Power under Jawaharlal Nehru Solar Mission, both Solar Thermal and PV, clean coal technologies, CCTs, i.e., supercritical power plants, integrated gasification combined cycle (IGCC), and fluidized bed combustion (FBC) are key to the success of Green Power Mission for India. Carbon capture and sequestration (CCS) is considered as the frontier Green Energy technology. CCS technology is still in the demonstration phase, and it is important that India is not left behind in this area. While there is a considerable amount of work already underway domestically, there may still be a need for research collaborations and knowledge sharing and transfer. Areas of research in CCS include development of new adsorbents, better process integration of capture equipment, and conversion of CO2 to useful products, among others. The important challenge of energy penalty in CCS being faced worldwide can be met through the use of Concentrated Solar Power (CSP) for supplementing steam for regeneration in a solvent-based post-combustion CO2 capture in thermal power plants. Low Carbon Technologies (LCT) and carbon capture and sequestration (CCS) are key factors for energy security and environmental sustainability, and the same are put forward in this chapter leading to an opportunity for course-correction in our thinking in Green Power.
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paper_title: Reassessing the Efficiency Penalty from Carbon Capture in Coal-Fired Power Plants

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This paper examines thermal efficiency penalties and greenhouse gas as well as other pollutant emissions associated with pulverized coal (PC) power plants equipped with postcombustion CO2 capture for carbon sequestration. We find that, depending on the source of heat used to meet the steam requirements in the capture unit, retrofitting a PC power plant that maintains its gross power output (compared to a PC power plant without a capture unit) can cause a drop in plant thermal efficiency of 11.3-22.9%-points. This estimate for efficiency penalty is significantly higher than literature values and corresponds to an increase of about 5.3-7.7 US¢/kWh in the levelized cost of electricity (COE) over the 8.4 US¢/kWh COE value for PC plants without CO2 capture. The results follow from the inclusion of mass and energy feedbacks in PC power plants with CO2 capture into previous analyses, as well as including potential quality considerations for safe and reliable transportation and sequestration of CO2. We conclude that PC power plants with CO2 capture are likely to remain less competitive than natural gas combined cycle (without CO2 capture) and on-shore wind power plants, both from a levelized and marginal COE point of view.
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paper_title: Innovative Absorber/Stripper Configurations for CO2 Capture by Aqueous Monoethanolamine

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The state-of-the-art technology to capture CO2 from coal-fired power plants is absorption/stripping with aqueous monoethanolamine (MEA). The energy consumption in stripping can be 15−30% of the power-plant output. A rigorous rate-based model for CO2−MEA−H2O was used to simulate several flowsheet alternatives that reduce the energy requirement using Aspen Plus with RateFrac. Results were calculated for vapor recompression, multipressure, and simple strippers at 5 and 10 °C approach temperatures and 70, 90, and 95% CO2 removal. The “equivalent work of steam/mole of CO2 removed” and the reboiler duty were used to compare the proposed schemes and to show the shift of energy use from work to heat. The total equivalent work for multipressure was less than that for the simple stripper by 0.03−0.12 GJ/(ton of CO2), and the reboiler duty was less by 0.15−0.41 GJ/(ton of CO2). The multipressure with vapor recompression is an attractive option because it utilizes the overhead water vapor latent heat to reduce reboil...
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paper_title: Expert elicitations of energy penalties for carbon capture technologies

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Abstract This paper describes the results of expert assessments about the range of likely energy penalties (EP), the energy required to capture and compress CO 2 , for coal power plants in 2025 for six capture technologies under three different policy scenarios. Expert opinions about the EP of each technology varied substantially. Measuring EP in terms of the fractional decrease in output per unit input, we found that a scenario of worldwide carbon pricing leads to a decrease in the mean energy penalty of 1–10% across the technologies, and a scenario of increased US government research and development (R&D) funding leads to a decrease in the mean energy penalty of 6–14%. EP for pre-combustion capture showed the smallest improvement from R&D and carbon pricing, while EP for post-combustion capture with membranes or “other” approaches showed the largest improvement. Although other factors will also affect costs, EP is a large component and these results suggest that capture costs are likely to fall both through investments in research and through the process of commercializing the technology in response to carbon prices. We summarize the challenges for each technology that were described by the experts, as well as the quantitative results.
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paper_title: Carbon Capture in the Cement Industry: Technologies, Progress, and Retrofitting

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Several different carbon-capture technologies have been proposed for use in the cement industry. This paper reviews their attributes, the progress that has been made toward their commercialization, and the major challenges facing their retrofitting to existing cement plants. A technology readiness level (TRL) scale for carbon capture in the cement industry is developed. For application at cement plants, partial oxy-fuel combustion, amine scrubbing, and calcium looping are the most developed (TRL 6 being the pilot system demonstrated in relevant environment), followed by direct capture (TRL 4-5 being the component and system validation at lab-scale in a relevant environment) and full oxy-fuel combustion (TRL 4 being the component and system validation at lab-scale in a lab environment). Our review suggests that advancing to TRL 7 (demonstration in plant environment) seems to be a challenge for the industry, representing a major step up from TRL 6. The important attributes that a cement plant must have to be "carbon-capture ready" for each capture technology selection is evaluated. Common requirements are space around the preheater and precalciner section, access to CO2 transport infrastructure, and a retrofittable preheater tower. Evidence from the electricity generation sector suggests that carbon capture readiness is not always cost-effective. The similar durations of cement-plant renovation and capture-plant construction suggests that synchronizing these two actions may save considerable time and money.
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paper_title: Process Integration of Low Grade Heat in Process Industry with District Heating Networks

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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.
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paper_title: Comparison of different mathematical programming techniques for mass exchange network synthesis

paper_content:

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.
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paper_title: Process intensification and integration of solar heat generation in the Chinese condiment sector - A case study of a medium sized Beijing based factory

paper_content:

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.
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paper_title: Multi-objective pinch analysis for power system planning

paper_content:

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.
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paper_title: Recent Developments and Challenges in Optimization-Based Process Synthesis.

paper_content:

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.
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paper_title: Simultaneous synthesis of mass exchange networks for waste minimization

paper_content:

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.
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paper_title: Systematic optimization methodology for heat exchanger network and simultaneous process design

paper_content:

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%.
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paper_title: Capital and total cost targets for mass exchange networks: Part 1: Simple capital cost models

paper_content:

Abstract This part of the paper builds on the developments of Part 1. It starts by developing a targeting method for tray columns using detailed capital costing methods. The number of units, column diameters and tray spacings, and the distribution of units and trays will all be considered. The limitations of stages targeting are also discussed, leading to an explanation of why stages targets may be beaten, and showing how continuous contactors are more analogous to heat exchangers than stagewise contactors. A procedure for determining capital cost targets for networks of continuous contactors (usually packed columns) is then developed. Networks featuring different exchanger specifications are also dealt with. As before, capital cost targets are combined with operating cost targets to give total annual cost targets. The design of networks to meet the targets is then discussed. Systems featuring significant differences in exchanger specifications may require some deviation from ideal (vertical) driving force use. The examples presented in this part of the paper demonstrate that the targets are accurate enough for preliminary design as well as pre-design optimisation. The work in both parts of this paper reduces the amount of design work required when evaluating processes at the conceptual stage.
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paper_title: A Critical Review and Annotated Bibliography for Heat Exchanger Network Synthesis in the 20th Century

paper_content:

This paper provides a critical review of the literature on heat-exchanger network synthesis, the most commonly studied problem in process synthesis. After a review of solution methods, we present the chronological milestones in the development of the field and we discuss separately each of 461 related works leading up to the turn of the century. Then, we present several classification schemes of this body of work based on a number of modeling and algorithmic criteria. Finally, we offer a critical assessment of the current status of research in this area and provide suggestions for future research.
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paper_title: Fairly Linear Mixed Integer Nonlinear Programming Model for the Synthesis of Mass Exchange Networks

paper_content:

A fairly linear optimization model for the synthesis of mass exchange networks has been developed. Superstructure, detailed modeling equations, and solutions of example problems are presented. The predominantly linear character of the model can be kept as long as single-component mass exchange network synthesis problems and packed columns as mass exchangers are considered. At the cost of introducing nonlinear constraints, the optimization model can be extended to handle multicomponent problems and staged columns as well. The new model applies the key ideas of the simultaneous heat exchanger network synthesis model of Yee and Grossmann [Comput. Chem. Eng.1990, 14 (10), 1165-1184].
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paper_title: Simultaneous Heat Exchanger Network Synthesis Involving Nonisothermal Mixing Streams with Temperature-Dependent Heat Capacity

paper_content:

Heat exchanger network synthesis (HENS) is faced with the dilemma of substantial nonisothermal mixing and nonconstant thermal properties of streams against the higher computational efficiency required to solve mathematical programming models with a large amount of variables and high nonlinearity. In this work, by replacing the conventional binary variable in a HENS model, a nonlinear approximation term is developed to indicate the existence of a heat exchanger so as to reduce the amount of variables and constraint as well as enhance the model’s computational efficiency. With this approximation, a new HENS model was formulated considering simultaneously nonisothermal mixing and temperature-dependent heat capacity flow rate. All the variables of the model are stated with clear upper and lower bounds. A 10-stream (5 hot process streams and 5 cold process streams) benchmark HENS problem is solved by the developed model. The results show that the proposed model can generate a better cost-optimal heat exchanger...
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Title: A Review on Heat and Mass Integration Techniques for Energy and Material Minimization During CO2 Capture
Section 1: Introduction
Description 1: Introduce the main challenges of CO2 capture processes and the imperative for energy and material minimization. Discuss heat and mass exchanger network retrofitting as a potential solution.

Section 2: Review of synthesis methods for heat and mass exchanger networks
Description 2: Provide an overview of methodologies for the synthesis of heat and mass exchanger networks, including both sequential and simultaneous synthesis methods.

Section 3: The sequential synthesis method
Description 3: Describe the sequential synthesis of heat and mass exchanger networks using pinch concepts and graphical illustrations.

Section 4: The simultaneous synthesis method
Description 4: Explain the simultaneous synthesis of heat and mass exchanger networks using mixed-integer nonlinear programming (MINLP) and other mathematical programming techniques.

Section 5: Brief overview of process integration as an optimal process development strategy
Description 5: Discuss the principles and applications of process integration in CO2 capture systems, focusing on pinch analysis as a key technique.

Section 6: State of the art in the application of heat integration techniques
Description 6: Review recent developments and methodologies in heat integration to minimize energy consumption during CO2 capture.

Section 7: Application of pinch analysis and mathematical programming in CO2 capture systems
Description 7: Highlight the use of pinch analysis and mathematical programming for setting energy and material targets and optimizing CO2 capture systems.

Section 8: Energy penalty in CO2 capture systems
Description 8: Discuss the high energy requirements for CO2 capture and the specific challenges related to energy penalty in various CO2 capture technologies.

Section 9: Advances in energy penalty reduction during CO2 capture
Description 9: Present recent advancements and techniques for reducing energy penalty in CO2 capture systems, including the use of different solvents and waste heat utilization.

Section 10: Recent highlights on heat and mass exchanger network synthesis
Description 10: Summarize the latest research trends and methodologies for the synthesis of heat and mass exchanger networks, highlighting the integration of pinch analysis and mathematical programming.

Section 11: Heat and mass exchanger networks for energy and material minimization
Description 11: Discuss the role of heat and mass exchanger networks in reducing energy and material consumption in CO2 capture applications.

Section 12: Conclusions
Description 12: Provide a summary of the review’s key findings and the significance of heat and mass integration techniques in minimizing energy and material consumption in CO2 capture processes.

Section 13: Future research outlook
Description 13: Suggest potential areas for future research, including the development of combined heat and mass integration networks and the application of hybrid optimization techniques.