A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB001 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB002 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB003 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB004 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB005 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB006 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB007 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB008 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB009 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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). <s> BIB010 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB011 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB012 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB013 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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. <s> BIB014 </s> A review on heat and mass integration techniques for energy and material minimization during CO2 capture <s> Introduction <s> 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... <s> BIB015
Carbon capture and storage (CCS) is a promising technology that aims at reducing CO 2 emissions from large point sources such as power plants  BIB013 BIB015 . However, high energy demands and excessive material usage associated with CO 2 compression and separation processes have been the main challenges currently facing the commercialization of most CO 2 capture and storage technologies BIB010 . There is a need to save energy and minimize material usage during CO 2 capture to ensure the economic advantage of the capture technology BIB007 BIB008 . This is because, the cost of energy and materials for CO 2 capture has increased and this trend is expected to continue with an increase of about 13.4% by the year 2040 due to consistent high energy demand from many industrialized nations globally  . The challenge of energy and excessive use of materials in process industries can be tackled to a large extent by minimizing the consumption of energy and mass  . In the context of this review, energy refers to the heat required during sorbent regeneration, while material (mass) refers to the mass separating agents (sorbents) and external utilities such as cooling water and steam which ought to be minimized during CO 2 capture. Heat and mass exchanger network retrofitting is envisaged as a promising option for reducing energy and material consumption which could lead to enhanced economic and environmental sustainability. The main aim of heat exchanger networks (HENs) and mass exchanger networks (MENs) retrofitting is to decrease the external energy demand and extra material consumption by increasing heat and mass exchange simultaneously among process streams in an existing process plant BIB005 BIB001 . HENs and MENs retrofitting can be performed using pinch analysis and/or mathematical programming. Over the past decades, systematic methods based on simultaneous mathematical programming and sequential techniques have been applied to achieve improved energy and material minimization in chemical process industries BIB005 . Literature is rich in various process integration methods to minimize excessive heat energy consumption and material usage in different industrial processes. For example, El-Halwagi and Manousiouthakis BIB001 suggested the synthesis of mass and heat exchanger networks for effective material and heat minimization in industrial processes. Considering the need for energy minimization and effective material usage in energy-intensive industrial processes, some authors focused on distillation processes BIB011 BIB009 , bioethanol production process BIB003 , calcium looping systems BIB006 , and COG sweetening BIB001 . Most of the reports available on CO 2 capture studies have focused on developing materials for CO 2 capture and storage BIB006 BIB014 BIB012 without considering how to minimize its associated high energy requirements. Few studies that discussed ways to minimize high energy penalty and material minimization considered the use of additives such as piperazine and KOH to reduce the energy requirement for CO 2 absorption using monoethanolamine  BIB002 BIB004 . However, it is worthy to note that the techniques available for CO 2 capture do not only involve gas-liquid absorption, but also the use of solid materials and membranes. Techniques for minimization of energy and material consumption during CO 2 capture using solid sorbents have not been given much attention in literature. Application of HENs and MENs in this field could proffer a solution to energy and material minimization. Major techniques that have been used to synthesize HENs and MENs in the past have been summarized in Fig. 1 under simultaneous and sequential techniques. This review presents exhaustive information on the potential application of HENs and MENs as an optimal process integration strategy for energy and material minimization during CO 2 capture. The paper begins with the presentation of an optimal process development strategy during CO BIB013 capture, followed by the synthesis techniques for HENs and MENs. Synthesis of a combined heat and mass exchange network for minimization of energy and material consumption during CO 2 capture is then discussed because of the integral relationship between heat and mass during CO 2 capture. At the end of this review, a combined technique for the synthesis of heat and mass exchanger networks is suggested as a strategy to fully harness the benefits inherent in simultaneous optimization of the two networks using mathematical programming techniques. Finally, future prospects for energy penalty reduction in various CO 2 capture technologies are highlighted and future research topics suggested. A schematic overview of this review is presented in Fig. 2 . 