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Use cascade analysis to optimize water networks
Abstract
The use of a numerical techniques such as water pinch analysis (WPA) and water cascade analysis (WCA), for identifying fresh water and wastewater targets, are discussed. The techniques eliminates the tedious and time consuming steps of graphical targeting approaches. WPA involves two steps firstly setting the minimum freshwater and wastewater flowrates and second one is designing network to achieve the baseline targets. The main objective of the WCA is to establish the baseline water targets for a process after using available water sources within the process to meet its water sinks. The first step in WCA is to set the interval water balance table to determine the net water source or net water sink at each concentration level. Next, the water concentration difference, the difference between concentration at intervals k and k+1 is calculated. The next key step in WCA is to establish the freshwater and wastewater targets for the process. The systematic approach of WCA allows the technique to be automated and translated into any computer language for software development. WCA simplifies the task of incorporating the water surplus diagram into computer software by eliminating the tedious iterative steps involved in constructing the diagram.
... This case study involves the integration of water-using processes in a Malaysian paper mill [18]. The plant recycles wastepaper, which is converted into pulp and cleaned in the de-inking pulper (DIP). ...
... The plant consumes 19% less water than it would without any reuse network, but the savings still fall far short of the true conservation potential; thus, the installed network serves to demonstrate how the absence of systematic design tools can lead to resource conservation solutions that are unable to maximize the potential benefits intended. For example, pinch analysis indicates that the minimum possible fresh water demand with maximum reuse/recycle is 848.1 ton/h, which represents a reduction of 65% relative to the baseline; the corresponding effluent generation for this solution is 539.4 ton/h, which is 75% less than the quantity discharged without water reuse/recycle [18]. However, many methods do not allow the designer to explicitly specify the level of network complexity, which as discussed earlier may significantly affect capital cost, system robustness, and ease of retrofit, operation or maintenance. ...
... These figures represent sizable reductions in water flow, along with the associated operating and environmental costs, for a retrofit scheme that involves introducing a relatively small number of conduits for internal water reuse. For example, the company policy is to reduce water costs by 30%, then the simple network developed by this procedure will be sufficient to meet the resource Table 1 Limiting data for paper mill water integration case study [18] Water sinks, D j F j (ton/h) C j (ppm) conservation objective. Different degrees of water savings can be achieved at progressively higher levels of network complexity, as shown in Fig. 6. ...
The implementation of resource conservation schemes in industry can be enhanced through the application of systematic design methodologies. In particular, process integration methods allow resource consumption and waste generation in industrial plants to be reduced through the identification of efficient material reuse/recycle schemes. Various approaches, ranging from graphical pinch analysis to mathematical programming, have been developed by different researchers. Mathematical programming techniques provide considerable flexibility in the representation of network design problems, although in many cases, these approaches result in mixed integer non-linear programming (MINLP) models which are difficult to solve. This paper presents a simplified approach using a zero–one programming or “knapsack” formulation for the design of industrial material reuse/recycle networks. It is possible to solve the resulting model using an efficient heuristic algorithm based on adaptive particle swarm optimization. Two sample applications are provided to illustrate the methodology. The first case shows the application of the methodology to the implementation of industrial water conservation and the second case demonstrates its use in the design of a hydrogen gas reuse/recycle scheme in a refinery.
... PA was initially introduced to address the problem of conserving energy in process plants (Linnhoff and Flower 1978). It was soon extended to consider many different system-wide applications for resource conservation (El-Halwagi 2017;Foo 2012;Klemeš 2013). A recent study by Tan et al. (2016) examined the problem of efficiently utilizing available financial resources to implement a number of potential risk reduction and pollution prevention measures by employing a PA approach. ...
... PA was next applied in various process engineering fields, such as in designing material resource conservation networks, water recycle/reuse and hydrogen systems, production planning, environmental management and others. Comprehensive reviews of such applications can now be found in the pertinent literature, review papers and handbooks (El-Halwagi 2017;Foo 2012;Tan et al. 2015). Moreover, various methods using PA were further elaborated, including mathematical, algorithmic and graphical approaches that offered fresh process improvement insights. ...
... Grooms et al. (2005) presented a mathematical programming approach for the design of an interception and allocation network of process sources and sinks based on the property integration principles, while Ponce-Ortega et al. (2010) presented a mathematical programming approach for direct recycle/reuse in mass exchange networks taking into account process and environmental constraints. Furthermore, Foo et al. (2006) used an algebraic cascade technique to determine rigorous targets for minimum fresh consumption and waste discharge, while establishing an optimal water network configuration. Later, an extended PA approach was developed for optimizing resource conservation networks (RCN) in the presence of property-based constraints . ...
The problem of solvent selection in an industrial process has been examined in a number of different approaches, often including single- and multi-criteria optimization techniques. Traditionally, it has been addressed using techno-economic analyses and mathematical modeling techniques usually aiming at optimizing certain economic objectives such as maximizing profitability, minimizing cost and solvent usage. The proposed methodology offers an insightful environmental risk management framework for determining the optimal solvent profiles that can effectively match process requirements and at the same time ensure safe process performance. Through this approach, the risk aspects of utilizing a number of available solvents and their mixtures for particular process tasks were first examined and targets for the selection based on solvents’ safety characteristics, such as the permissible exposure limit, were established. This approach, when considered in conjunction with economic performance assessment, can be substantially useful, because it enables prioritization of solvent selection options based on insightfully tracking the degree of environmental risk performance in systems with complex chemical characteristics. A pinch analysis methodology enables the direct targeting of minimum solvent(s) utilization and optimal allocation of the appropriate solvents to process sinks based on their degree of environmental risk. The methodology can also provide solvent selection and design insights for enhanced usage in any industrial process system while highlighting appropriate sustainable solutions. A case study is finally presented to illustrate the applicability of the proposed methodology.
Graphical abstract
Graphical representation of the solvent selection and allocation problem addressed using the risk-based pinch analysis approach (where Ri is the risk index of solvent i, Wi, Ffr, Gj are the flowrates of sources, fresh and required flowrates of the sinks, respectively).
... Automated targeting technique was initially developed by El-Halwagi and Manousiouthakis (1990) for MEN synthesis. The concept of this technique is similar to algebraic targeting technique cascade analysis Foo et al., 2006). ...
... Note that the net material flow rate at the second-to-last concentration (δn-1) level corresponds to the waste discharge flow rate (FW) of the network. This is equivalent to the cascade analysis technique Foo et al., 2006). ...
... -27- (Ng et al., 2009b) Foo et al. (2006 reported that impurity load cascading is also essential to ensure a feasible RCN. As in the material flow rate cascade, the residue of the impurity load of each concentration level k (εk) is cascaded down to the next concentration level. ...
Recent environmental trends have made the process industries adopt the reuse/recycle strategy to reduce their waste as well as to use the resources more efficiently. In order to define the target of fresh water consumption and wastewater generation and to synthesize reuse/recycle water network in process industries, two major approaches have been used namely pinch based and mathematical optimization approach. In this research work, the hybrid automated targeting technique for batch process (Foo, 2010) is further developed by including fuzzy optimization to analyze the uncertainty trade-off between storage capacity and minimum target of fresh water consumption. Five case studies are analyzed using this newly developed technique. Among the Pareto-optimal solutions found by using the method of Foo (2010), fuzzy optimization developed in this study can effectively find the best compromise solution between storage capacity and minimum target of fresh water consumption that should be implemented in the project of process integration or cleaner production. This technique can assist the decision makers in the process industries to identify strategies for water conservation.
... Numerous research works have been carried out to systematically address water reuse/recycle problems. Significant advances were achieved in the insightbased pinch analysis techniques to target the minimum fresh water and wastewater flow rates for various water network synthesis problems, ranging from direct reuse/recycle, [5][6][7][8][9][10][11][12][13][14][15] regeneration, 5,6,13,[16][17][18][19][20][21][22] pretreatment, 23 and wastewater treatment. 12,[24][25][26][27][28] Detailed reviews for most of these techniques were reported by Bagajewicz 29 and Foo. ...
... Numerous research works have been carried out to systematically address water reuse/recycle problems. Significant advances were achieved in the insightbased pinch analysis techniques to target the minimum fresh water and wastewater flow rates for various water network synthesis problems, ranging from direct reuse/recycle, [5][6][7][8][9][10][11][12][13][14][15] regeneration, 5,6,13,[16][17][18][19][20][21][22] pretreatment, 23 and wastewater treatment. 12,[24][25][26][27][28] Detailed reviews for most of these techniques were reported by Bagajewicz 29 and Foo. ...
... Spriggs et al. 45 later proposed the use of the material recoVery pinch diagram (MRPD) 7,10 for the fixed flow rate problems, however without detailing the targeting procedure. Recently, Foo 46 extended the use of water cascade analysis (WCA), which was originally developed for a single water network 8,13 into IPWI of the fixed flow rate problems. However, the approach requires the generation of all alternative IPWI schemes before the minimum water flow rate targets can be determined. ...
This paper is part 1 of a series describing a new algorithm for targeting minimum fresh resource and waste flow rates for an interplant resource conservation network (IPRCN). The IPRCN enables the reuse of the excess process sources among different networks, which reduces the consumption of fresh resource and generation of waste simultaneously. Four hypothetical examples are presented to illustrate both concentration- and property-based utility gas and water integration problems. In addition, the proposed targeting algorithm is adapted in the synthesis of total resource network, where the minimum regeneration and waste treatment flow rates can be targeted prior to the detailed design of an IPRCN.
... Apart from the earliest developments in energy conservation, 1-3 much recent process integration work on water network synthesis has been reported in the literature, ranging from insight-based pinch analysis to mathematical optimization approaches. Research in water network synthesis through pinch analysis has evolved from the targeting of minimum fresh water and wastewater flowrates [4][5][6][7][8][9][10][11][12][13] to the targeting of minimum regeneration [14][15][16][17][18] and wastewater treatment flowrates. [19][20][21] Apart from the insight-based approach, various mathematical optimization approaches have been developed to complement the insight-based approach in dealing with more complex problems, for example, multicontaminant systems [22][23][24] and complex operational constraints which include limiting the number of pipeline connections, 25 forbidden/ compulsory matches between water-using processes, 26,27 and process uncertainty, 28,29 etc. ...
... These authors also proposed the use of a centralized mixing and interception network (termed as "centralized utility hub" in this current work) for conducting byproduct or waste exchange among several process plants within an eco-industrial park. Recently, Foo 32 extended the use of water cascade analysis which was developed for flowrate targeting in a single water network, 7,12,13 to IPWI. However, the proposed work requires time-consuming steps as alternative integration schemes need to be considered to locate the true minimum water flowrates among all the schemes. ...
... This problem is categorized as a fixed flowrate problem in recent work in water network synthesis. [5][6][7][8][9][10][11][12][13]16,[19][20][21] The assumption of a fixed water flowrate differs slightly from the conventional fixed load problem 4,15,17,18 in which processes are modeled as mass exchange units with a fixed contaminant load which is transferred to a water stream. In the fixed flowrate case each process may function both as a sink and a source, in which case the properties of the inlet and outlet streams do not affect each other. ...
To date, most work on water network synthesis has been focusing on a single water network. The increase of public awareness toward industrial ecology has inspired new research into interplant water integration (IPWI). In this context, each water network may be grouped according to the geographical location of the water-using processes or as different plants operated by different business entities. Water source(s) from one network may be reused/recycled to sink(s) in another network. In this work, two different IPWI schemes, that is, “direct” and “indirect” integration are analyzed using mathematical optimization techniques. In the former, water from different networks is integrated directly via cross-plant pipeline(s). A mixed integer linear program (MILP) model is formulated and solved to achieve a globally optimal solution. In the latter, water from different networks is integrated indirectly via a centralized utility hub. The centralized utility hub serves to collect and redistribute water to the individual plants, and may even function as a shared water regeneration unit. For the indirect integration scheme, a mixed integer nonlinear program (MINLP) is formulated and solved using a relaxation linearization technique to obtain an optimal solution.
... Numerous research works have been carried out to systematically address water reuse/recycle problems. Significant advances were achieved in the insightbased pinch analysis techniques to target the minimum fresh water and wastewater flow rates for various water network synthesis problems, ranging from direct reuse/recycle, [5][6][7][8][9][10][11][12][13][14][15] regeneration, 5,6,13,[16][17][18][19][20][21][22] pretreatment, 23 and wastewater treatment. 12,[24][25][26][27][28] Detailed reviews for most of these techniques were reported by Bagajewicz 29 and Foo. ...
... Numerous research works have been carried out to systematically address water reuse/recycle problems. Significant advances were achieved in the insightbased pinch analysis techniques to target the minimum fresh water and wastewater flow rates for various water network synthesis problems, ranging from direct reuse/recycle, [5][6][7][8][9][10][11][12][13][14][15] regeneration, 5,6,13,[16][17][18][19][20][21][22] pretreatment, 23 and wastewater treatment. 12,[24][25][26][27][28] Detailed reviews for most of these techniques were reported by Bagajewicz 29 and Foo. ...
... Spriggs et al. 45 later proposed the use of the material recoVery pinch diagram (MRPD) 7,10 for the fixed flow rate problems, however without detailing the targeting procedure. Recently, Foo 46 extended the use of water cascade analysis (WCA), which was originally developed for a single water network 8,13 into IPWI of the fixed flow rate problems. However, the approach requires the generation of all alternative IPWI schemes before the minimum water flow rate targets can be determined. ...
Cited By :18, Export Date: 4 January 2015
... The latter approach is rather difficult to formalize both at the targeting and synthesis stages. However, there are some references to the computer implementation of WSD using so-called "cascade tables" -Water Cascade Analysis (WCA) -see Manan et al. (2004), Wang et al. (2006), Foo et al. (2006) In certain cases it is possible to group the contaminants according to their properties. In particular, Kutepov et al. (2002) used an integral characteristic of the water contamination (chemical oxygen demand) during the design of WEN of the textile industry. ...
... And the water sources of "lower quality" are believed to be either free of charge or very cheap. The "multiple utilities" problem was taken into account by "Limiting composite curves" approach (Wang & Smith, 1995), as well as by "Water cascade analysis" (Foo et al. (2006)), and the "Material Recovery Pinch Diagram" approach (Alwi & Manan, 2007), etc. Nevertheless, none of the above contributions adress the "economic efficiency". ...
Вторая часть публикации посвящена обзору современных концептуальных методов (известных также под названиями интуитивных, последовательных, иерархических методов) поддержки принятия проектных решений в устойчивом проектировании промышленных схем водного хозяйства, то есть схем водопотребления, схем очистки природных и сточных вод.Проанализированы предложенные в литературе подходы к реализации концептуальных методов устойчивого проектирования как на стадии определения цели проектирования – потенциала экономии воды (путем графического или графоаналитического описания промышленных схем водного хозяйства), так и на стадии синтеза оптимальной схемы водного хозяйства.
... The seminal work for insight-based graphical techniques was initiated by Wang and Smith (1994) who presented the pinch targeting approach for fixed load problems, based on the more generalized mass exchange network synthesis problems (El-Halwagi and Manousiouthakis, 1989). More recently, various approaches have been developed to handle the fixed flowrate problems (Hallale, 2002;El-Halwagi et al., 2003;Manan et al., 2004;Prakash and Shenoy, 2005;Foo et al., 2006;Almutlaq et al., 2005). The main advantage of the graphical targeting tools is its ability to incorporate conceptual insights during network synthesis. ...
Different techniques for the synthesis of industrial water reuse/recycle networks have been developed in recent process integration research. These tools range from graphical pinch analysis approaches to mathematical programming models. The latter have the advantage of being flexible enough to incorporate various water network constraints, but in many cases these are often non-linear, thus making the identification of global optima difficult. Recent work has demonstrated the effectiveness of metaheuristic algorithms such as particle swarm optimization (PSO), for finding good solutions these problems. This work describes the use of a modified PSO for solving mixed integer non-linear programming (MINLP) models for water network synthesis. By incorporating a mutation operator for the binary variables in the model, the algorithm is able to escape sub-optimal network topologies and proceed towards better solutions than can be found with ordinary PSO. Two case studies involving water recycle/reuse are used to demonstrate the new design methodology.
... Many past works proposed graphical approaches (Wang & Smith, 1994;Hallale, 2002;El-Halwagi et al., 2003;El-Halwagi, 2006) and algebraic methods (Sorin & Bedard, 1999;Manan et al., 2004;El-Halwagi, 2006;Foo et al., 2006) to calculate the target for minimum fresh resource and maximum recycling. These works mainly focus on continuous, steady state processes, which lie in the background, while the recycling network and its respective maximum recycling target lie in the foreground of the analysis. ...
Mass integration has been used for reducing the amount of process waste and environmental impact. Despite its long history, new challenges constantly arise with the use of process simulation tools offering platforms for rigorous process models. Therefore, the typical mass integration framework requires modifications to accurately account for the process performance. In this work, a novel sequential methodology is presented to realize a recycle network with rigorous process models. Initially, under the hypothesis of constant compositions of the process sources, an optimal ranking of the process sinks is determined. The optimal recycling network thus obtained is then used for a sequential methodology considering rigorous process models. The violations of process constraints are handled at each sequential step through the concept of “tightening constant”. The application of the sequential methodology to two case studies proves its ability to provide good approximations of the global optima with low computational effort.
... In this approach, the procedure contains two steps that are minimum freshwater targeting and network design/retrofit (Shenoy and Shenoy, 2015). Many different techniques have been developed for minimum freshwater targeting including water-source and water-sink composites (Dhole et al., 1996), evolutionary tables (Sorin and Bedard, 1999), water surplus diagram (Hallale, 2002), material recovery pinch diagram (Prakash and Shenoy, 2005), water cascade analysis (Foo et al., 2006), algebraic targeting approach (Almutlaq et al., 2005), source composite curve (Bandyopadhyay, 2006), automated targeting model (Ng et al., 2009a) and improved composite table (Deng and Feng, 2011). There are also numerous methods for the design step. ...
... Targets will be clearly set and their achievement measurable. Tools like water pinch analysis (Wan Alwi and Manan, 2013), water cascade analysis (Foo et al., 2006) or water management hierarchy will become standard not only for industrial but also for urban applications. Systems will be optimised according to multiple criteria. ...
Wastewater management is included in one of the 17 Sustainable Development Goals (SDGs): SDG 6 is dedicated to water and sanitation and sets out to "ensure availability and sustainable management of water and sanitation for all". SDG 6 expands the Millennium Development Goals (MDGs) focus on drinking water and basic sanitation to now cover the entire water cycle, including the management of water, wastewater and ecosystem resources. A UN report in 2017 states that likely over 80% of the wastewater worldwide is still discharged without adequate treatment. In several countries the wastewater management is nowadays a norm, but still there are open discussions about the kind of approach to be adopted, i.e. centralisation vs. decentralisation. The choice of the adopted technologies is strictly linked to environmental performances and economical aspects; one of the possible causes for the still enormous amount of untreated wastewater discharged into the environment can be the low "willingness to pay" for this kind of service and therefore a great focus should be given to all the technologies that are able to lower the treatment costs still maintaining reliable and robust performances in the long term. When considering wastewater as a carrier of valuable primary chemicals that can be easily converted to marketable products (fertilisers, bio-plastics, soil conditioners, biofuels, etc.), and as well as a relevant source of "new water" to be used for specific purposes, wastewater and runoff management can be highlighted as one of the most exciting challenges and occasions for a sustainable development in the near future. The paper aims to clarify the future role of CWs in circular economy, resource-oriented, and ecosystem services approaches, which want to respond to sanitation worldwide and the future research needs. We give an overview on how the conventional wastewater treatment scheme (what we call "waste paradigm") should move towards more sustainable water and biogeochemical cycles following the new resource-oriented, circular economy and ecosystem service views. On this basis, we review the potential application of CWs within this new, and needed, paradigm. Finally, a meta-analysis shows that the scientific community involved in CWs should put more effort in making CWs more suitable for these new tasks.
... Among the various methods and objectives of process integration, mass integration through direct recycling and mass exchange networks is a methodology that allows recovering part of the waste streams of a process (i.e., process sources) and reusing them in appropriate process units (i.e., process sinks), thus reducing the purchase of fresh resources [6] [7]. Many past works have utilized graphical approaches [8]- [10] and algebraic methods [11]- [13] to calculate the target for maximum recycling and, therefore, minimum fresh resource utilization. Such methods, although originally designed for continuous processes, have also been extended to batch processes [14]- [17]. ...
In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone constant refinement toward formulating and solving complicated process integration problems, less attention has been drawn to the problem of sequential applications of mass integration. This work addresses this problem by proposing an algorithm for optimal ordering of the process sinks in direct recycling problems, which is compatible with the typical mass integration formulation. The order consists in selecting the optimal sink at a specific integration step given the selection of the previous steps and the remaining process sources. Such order is identified through a succession of preemptive goal programming problems, namely of optimization problems characterized by more objectives at different priority levels. Indeed, the target for each sink is obtained by maximizing the total flow recycled from the available process sources to this sink and then minimizing the use of pure sources, starting from the purest one; the hierarchy is respected through a succession of linear optimization problems with a single objective function. While the conditional optimality of the algorithm holds always, a thorough statistical analysis including structured to random scenarios of process sources and process sinks shows how frequently the sequential ordering algorithm is outperformed with respect to the total recycled amount by a different selection of process sinks with the same cardinality. Two more case studies proving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithm are also identified to cover more aspects of the process integration framework.
... They in turn proposed an improved LCC and improved mass problem table to determine the targets of a FC water network with regeneration recycling 32 or regeneration reuse schemes. 33 On the other hand, several approaches have also been developed to handle water regeneration placement in the FF problems, such as WSD, 8 WCA, 18,23,34 improved LCC and CTA 16 and its extensions, 28,29 SCC. 17,26 Besides, a considerable amount of works were conducted on the synthesis of distributed eff luent treatment network. ...
Multiple partitioning interception units, such as floatation, flocculating settling, ultrafiltration, reverse osmosis, etc. are placed in series in practical wastewater treatment plant for the purpose of regeneration reuse/recycle, and/or for waste treatment for final discharge. Currently, no pinch-based approach addresses the flowrate targeting problem for the water network with multiple partitioning interception units. In this paper, the generalized Improve Problem Table (IPT) is firstly presented to target concentration- and property-based total water network with multiple partitioning interception units. The procedure for the generalized IPT approach is illustrated in detail by solving a revised literature example. The generalized IPT includes the deduced flowrate and mass balance equations for the water network with multiple partitioning interception units and they are utilized to check the feasibility of the results. The Excel Goal Seek feature is applied to determine the optimal solutions and they are validated via automated targeting model (Ng et al., 2009, Ind. Eng. Chem. Res.). The limiting composite curve and water supply line can be plotted on the basis of the data and the optimal solutions to show the net water demand and the optimal water supply of water network. Two revised literature examples are solved to show the feasibility of the proposed IPT in targeting the fixed flowrate (FF) or fix contaminant mass load (FC) water network problems. The applicability of proposed IPT is illustrated by solving the property-based wastewater interception and recovery system of an industrial case study.
... Later El-Halwagi (2006) developed graphical Material Recovery Pinch Diagram targeting tool to locate the regeneration unit within the water regeneration network. Foo et al. (2006) proposed algebraic water cascade analysis for targeting regeneration-recycle network. Targeting for water regeneration network were also carried out using the CTA by Agrawal and Shenoy (2006). ...
This work aims to improve the Composite Table Algorithm as a targeting tool for regeneration-recycle water network. It is demonstrated that some problems have the potential to achieve zero liquid discharge. A literature example on a petrochemical plant is used to show the applicability of the proposed method. MATLAB is utilised as a programming tool to facilitate the implementation of the developed method.
... The proposed extension is based on the addition of three new steps to locate the minimum consumption of pure and impure fresh water sources. Finally, Foo et al. (2006) illustrated a process involving a zero liquid discharge network in a paper mill using the WCA. Parand et al. (2013a) proposed some adjustments in WCA to allow the correct identification of infeasible targets, which are the major iterative issues of the method. ...
In this article, the water source diagram (WSD) (Gomes et al., 2007) is extended to the design of water networks involving both fixed flowrate and fixed contaminant load, as well as water loss/gain operations. The algorithm targets minimum external water consumption while simultaneously synthesizing the corresponding water system structure. In addition, it is shown that the WSD can be applied to water allocation problems (WAP) based only on water sources and sinks, maintaining its good performance. To illustrate the methodology, case studies handling hybrid water system are presented, including a zero wastewater discharge discussion and data from a Brazilian pulp mill.
... s are interchangeable, and hence can be handled with the same targeting tools (Foo, 2009). The first guideline for regeneration placement in the FF problems was proposed by Hallale (2002). Later El-Halwagi (2006) developed graphical Material Recovery Pinch Diagram targeting tool to locate the regeneration unit within the water regeneration network. Foo et al. (2006) proposed algebraic water cascade analysis for targeting regeneration-recycle network. Targeting for water regeneration network were also carried out using the CTA by Agrawal and Shenoy (2006). However, in dealing with highly integrated processes, i.e. where the turning point of LCC is not completely recognizable, this procedure is not c ...
This work aims to improve the Composite Table Algorithm as a targeting tool for regeneration-recycle water network. It is demonstrated that some problems have the potential to achieve zero liquid discharge. A literature example on a petrochemical plant is used to show the applicability of the proposed method.
MATLAB is utilised as a programming tool to facilitate the implementation of the developed method
... These studies are very useful in water conservation, wastewater reduction, energy efficiency improvement in enterprises and eco-industrial parks, and also provide the basis for policy arrangements for governments particularly those of water scarce areas. 法 可 粗 略 地 分 成 两 大 类 ： 基 于 理 解 的 方 法 （ insight-based method ） 和 数 学 规 划 优 化 方 法 （mathematic programming method） 。前者基于机理 概念，主要是夹点集成原理的各种变化方法；后者 基于超结构模型的数学规划优化解算。 （1）基于理解的方法 这类方法已经有 Foo [8] 的综述，可以粗略地说， 主要是基于水夹点方法，而且集中于单杂质组分的 水网络。Foo 将所有已发表的文献分为两大类：第 一类侧重以传质为基础的用水单元，把杂质移除负 荷固定，称为 " 固定负荷问题 " ，这主要是欧洲学 派在 1994～2000 年期间发表的成果为主；第二类 侧重于从水源-水阱方面来考察问题， 把它们之间流 量当成主要约束，称为 " 固定流量问题 " ，这主要 是亚洲学派 21 世纪用得较多的方法。当然，这二 者只是处理方法不同，对于同一个问题是可以互相 转换的。 这种基于理解的图表方法，从最开始的单一新 鲜水源，发展到多个水源，到含有杂质的不洁净水 源272829303132333435 ； 从只考虑回用发展到考虑回用-废水再生回 用/废水循环利用 [12,15,3637383940 ；从只考虑用水单元到考 虑 污 水 处 理 单 元 [19,21] ， 到 考 虑 总 水 网 络 系 统 TWN [ [J]. Chem. ...
The urgency of water crisis has attracted more and more research in the field of process systems engineering. Starting from describing the status of water crisis globally and in China, this paper introduces water crisis related policies from government and opinions from academic circles. Documentation retrieval for water network and virtual water studies since 1994 is conducted. The topic is systematically reviewed in three levels according to the scale size. (1) Water network integration and optimization in a single enterprise, including water using network (WUN), wastewater treatment network (WWTN), total water network (TWN), complete water network (CWN), and three special problems, which are cooling water systems, WUN with internal water mains, water network for batch processes. Water allocation and heat exchange network (WAHEN) problems and simultaneous process synthesis with heat and water integrations are also included. (2) Inter-plant multiple water network integration, including water networks integration in eco-industrial parks. (3) Virtual water and water footprints studies across prefectures/countries. These studies are very useful in water conservation, wastewater reduction, energy efficiency improvement in enterprises and eco-industrial parks, and also provide the basis for policy arrangements For governments particularly those of water scarce areas.
... These studies are very useful in water conservation, wastewater reduction, energy efficiency improvement in enterprises and eco-industrial parks, and also provide the basis for policy arrangements for governments particularly those of water scarce areas. 法 可 粗 略 地 分 成 两 大 类 ： 基 于 理 解 的 方 法 （ insight-based method ） 和 数 学 规 划 优 化 方 法 （mathematic programming method） 。前者基于机理 概念，主要是夹点集成原理的各种变化方法；后者 基于超结构模型的数学规划优化解算。 （1）基于理解的方法 这类方法已经有 Foo [8] 的综述，可以粗略地说， 主要是基于水夹点方法，而且集中于单杂质组分的 水网络。Foo 将所有已发表的文献分为两大类：第 一类侧重以传质为基础的用水单元，把杂质移除负 荷固定，称为 " 固定负荷问题 " ，这主要是欧洲学 派在 1994～2000 年期间发表的成果为主；第二类 侧重于从水源-水阱方面来考察问题， 把它们之间流 量当成主要约束，称为 " 固定流量问题 " ，这主要 是亚洲学派 21 世纪用得较多的方法。当然，这二 者只是处理方法不同，对于同一个问题是可以互相 转换的。 这种基于理解的图表方法，从最开始的单一新 鲜水源，发展到多个水源，到含有杂质的不洁净水 源272829303132333435 ； 从只考虑回用发展到考虑回用-废水再生回 用/废水循环利用 [12,15,3637383940 ；从只考虑用水单元到考 虑 污 水 处 理 单 元 [19,21] ， 到 考 虑 总 水 网 络 系 统 TWN [ [J]. Chem. ...
... The articles by Foo, 3 Bagajewicz and Faria, 4 and Dunn and El-Halwagi 5 present reviews on the methodologies for the synthesis of recycle and reuse mass integration networks. These methodologies can be classified as techniques that make use of graphical approaches, [6][7][8][9][10][11][12] algorithmic or algebraic techniques, [13][14][15][16][17][18][19] and formulations based on mathematical programing models. [20][21][22][23][24][25][26][27][28] Another set of articles based on mathematical programing approaches to address the problem of wastewater treatment system have also been proposed. ...
The proper use of the resources is one of the major concerns of the chemical and process industry. Resources in the form of mass and energy constitute the main raw materials for the industry that impact the processes from both economic and environmental considerations. Based on the well-known ideas for energy integration, several strategies have been recently proposed for the reuse of the wastewater streams to minimize fresh streams usage and wastewater discharged to the environment. Particularly, the synthesis of recycle and reuse mass integration networks constitutes a powerful tool that enables the simultaneous minimization of fresh water usage and wastewater discharge through the direct recycle of wastewater streams and/or their treatment and reuse in process equipments. Several techniques have been reported for the synthesis of mass integration networks. Most of them have been based on the composition of streams; however, many recycle streams are constituted by several components and are difficult to characterize based on composition. To address this problem, Ponce-Ortega et al. (2009) have recently proposed a model formulation for the optimization of direct recycle networks together with wastewater treatment processes to satisfy a given set of environmental regulations. This formulation incorporated constraints based on stream properties (e. g. pH, toxicity, chemical oxygen demand, color and odor) in addition to the composition constraints. The properties balances considered by Ponce-Ortega et al. (2009) are based on the concept developed by El-Halwagi et al. (2004) for the property integration defined as a functionality-based holistic approach for the allocation and manipulation of streams and processing units. Ponce-Ortega et al. (2010) extended their previous model to include a property interception network within the process considering both process and environmental constraints. However, even when those formulations incorporate environmental constraints, they are based on simple objective functions such as minimizing the consumption of fresh sources. If one performed a more global analysis, it could be assessed whether this type of solution yielded an increase on the environmental burdens somewhere else in the life cycle. For example, the treatment units required for the process sources may increase the pollution to the environment, or the use of one type of fresh source may reduce the pollution in the plant, but the pollution caused during the production of this fresh source may be higher than the one avoided in the plant. Therefore, life cycle assessment (LCA) provides a more suitable approach to evaluate the overall environmental loads associated with a process, product or activity that identifies and quantifies the materials and energy used as well as the wastes released to the environment. This paper presents a multiobjective optimization model for the synthesis of property-based recycle and reuse mass exchanger networks considering simultaneously economic and environmental impacts. The economic objective function considers the fresh sources costs, the treatment costs and the piping costs, whereas the environmental objective function is measured through the eco-indicator 99, which is based on the life cycle analysis methodology. The problem gives rise to a multiobjective mixed integer non linear programming model (moMINLP). A superstructure that yields a convex problem is proposed to guaranty a global optimal solution. Several examples are solved to show the applicability of the proposed model.
References: El-Halwagi, M. M., Glasgow, I. M., Qin, X. Y., & Eden, M. R. (2004). Property integration: Componentless design techniques and visualization tools. AIChE Journal, 50 (8), 1854-1869. Ponce-Ortega, J. M., Hortua, A. C., El-Halwagi, M. M., Jimnez-Gutirrez, A. (2009). A property-based optimization of direct recycle networks and wastewater treatment processes. AIChE Journal. 55 (9): 2329-2344. Ponce-Ortega, J. M., El-Halwagi. M. M., Jimnez-Gutirrez, A. (2009). Global optimization of property-based recycle and reuse networks including environmental constraints. In press in Computers and Chemical Engineering.
... Among the algorithmic methodologies, Wang and Smith 1 and Almutlaq and El-Halwagi 2 proposed methods for minimizing the use of fresh water. The optimal design of effluent treatment systems and water networks has been addressed by Wang and Smith 3 and Foo et al. 4 Ng et al. 5 considered aspects over regeneration opportunities and waste treatment. Of the methods based on graphical approaches, the major contributions have considered the minimization of fresh water, 6 recycling water networks, 7 optimization of single-contaminant regeneration/reuse systems, 8 identification of individual wastewater streams, 9 and regeneration and recycle through single treatment units. ...
This work presents a new discretization approach based on disjunctive programming for the pooling problem. The pooling problem has been subject of several studies in the area of process engineering because of its theoretical and practical relevance. It consists in blending materials in intermediate pools to obtain products within given specifications. The pooling problem is a non linear programming problem (NLP), which involves bilinear terms in the quality balances; therefore, it might yield several local optimal solutions. In general, the optimization methodologies used to solve the pooling problem are classified as follows: successive linear programming (SLP), Lagrangian approaches, convex envelopes, reformulation linearization techniques (RLT), branch and bound algorithms, piecewise underestimators and discretization approaches. Recently, Pham et al. (2009) presented a Convex Hull discretization approach that was able to solve the pooling problem to optimal or near optimal solutions. Pham et al. (2009) showed that for single quality problems, an exhaustive enumeration scheme was appropriate yielding most of the cases the optimal solution. Whereas, for multiple quality problems, an implicit enumeration scheme was recommended. In this work we present a discretization approach based on in disjunctive programming that does not require a pre-processing step unlike the implicit enumeration. The advantages of the proposed approach (when compared with a global optimization solver and the implicit enumeration approach) are shown by solving 7 cases of study, corresponding to multiple quality problems. For all the cases of study, near optimal solutions were found within shorter CPU times respect to other algorithms.
Pham, V.; Laird, C.; El-Halwagi, M. Convex hull discretization approach to the global optimization of pooling problems. Industrial and Engineering Chemistry Research. 2009, 48 (4), 1973-1979.
... Most of the pinch analysis methods have considered the first criterion for targeting the regeneration−reuse/recycle network. 8,[18][19][20][22][23][24][25][26]28 A little attention has been paid to the second one. 7, 35 Wang and Smith 7 addressed water network synthesis inclusion of the RR type regenerator. ...
In this study, an Extended Composite Table Algorithm is developed to target the minimum freshwater, regenerated water, and wastewater flow rates together with the minimum regeneration concentration and wastewater concentration for total water regeneration network. The approach is first demonstrated by assuming a fixed post-regeneration concentration. Considering that the post-regeneration concentration has the dominant influence on the total cost in the water regeneration problem, this assumption is relaxed by allowing it to shift in a feasible region. A new method, Composite Matrix Algorithm, is proposed to find such a region and a maximum feasible post-regeneration concentration. By incrementally changing the post-regeneration concentration, the relationship between the key parameters in the total water regeneration network can be analyzed quantitatively. Some graphical presentations are introduced to target total water regeneration problem when the removal ratio type regenerator is involved. Moreover, the effect of post-regeneration concentration to the total cost of the network is evaluated and discussed. To facilitate the implementation, MATLAB is used as a programing tool.
... Equivalent numerical tools for targeting minimum water flowrate have also been developed. The water cascade analysis (WCA) technique presented by Manan and coworkers (Manan et al. 2004;Foo et al. 2006) is the tabular equivalent to the water surplus diagram (Hallale 2002), with the iterative calculation steps having been eliminated. Almutlaq and El-Halwagi (2007) and Almutlaq et al. (2005) presented another cascade analysis tool that is based on the composite curves of El-Halwagi et al. (2003). ...
Process integration using membrane permeate of combined bleach effluent and some amount of raw effluent from a pulp mill section and paper machine section was explored in this study. COD was found to be the critical limiting constraint between COD and AOX when the back water of paper machines and Decker was used with the membrane permeate in a bleaching section. After process integration of some identified sections of the mill, the fresh water demand was reduced up to 28.97% and wastewater generation was also reduced by 30.21%. The use of UF permeate resulted in a 71.43% reduction in effluent flow, a 45.5% reduction in COD load and a 93.5% reduction in AOX load. The use of permeate obtained from UF+NF treatment resulted in a further reduction of 55.6% in effluent flow, 42% in COD load and 79.0% in AOX. After integration with UF permeate treatment, the cost savings is likely to be 45.5% while integration with UF+NF permeate is likely to result in a 62.07% reduction in treatment costs with 41.53% of the cost savings in the form of water cess. Assuming that the average production of the mill is 225 tpd, a savings of Rs 2.68 and Rs. 3.06 in the cost of production per kg of paper can be achieved by employing the proposed process integration scheme.
... Successful applications of water network synthesis in various process industries have been documented for both the water pinch and mathematical optimization approaches, including petrochemical complexes (Liu et al., 2005;Mann and Liu, 1999), chemical manufacturing (Feng et al., 2006;Forstmeier et al., 2005;Ku-Pineda and Tan, 2006;Mann, 2003), oil refineries (El-Halwagi et al., 1992;Wang and Smith, 1994), a steel plant (Tian et al., 2008), and pulp and paper mills (Chiang et al., 2006;Delgado et al., 2006;Foo et al., 2006;Jacob et al., 2002;Lovelady et al., 2007;Manan et al., 2007;Parthasarathy and Krishnagopalan, 2001;Yang et al., 2000). ...
Water system integration can minimize both fresh water consumption and wastewater discharge from the paper mills. In the present study, Pinch Technology was used to analyze and optimize the water network of an integrated paper mill. A system was developed and a limiting constraint (COD concentration) was identified based on investigations for water quality, and then minimum fresh water and wastewater targets were determined without considering water losses. The analysis was extended by estimating the additional input of fresh water required to balance the actual water losses. A nearest neighbor algorithm (NNA) was used to distribute the fresh and recycled water in the plant operations. Results showed that the flow rates of fresh water could be decreased up to 20.83 %.
This chapter presents an introduction to the water and energy integration into an eco-industrial park. First, the concepts associated with industrial symbiosis are presented. Then several optimization approaches for water integration into an eco-industrial park are presented. Then, some optimization formulations for the energy integration between different industrial processes are described. These approaches include direct recycling, exchanges between the different plants, and the possibility of installing a central shared facility to treat the waste streams. The application of the proposed optimization formulations is shown through several examples problems.
Material reuse/recycle has gained much attention in recent years for both economic and environmental reasons. Process integration techniques for water network synthesis have evolved rapidly in the past decade. With in-plant water reuse/recycle, fresh water and wastewater flowrates are reduced simultaneously. In this work, linear programming and mixed integer linear programming models that include piping cost and process constraints are developed to retrofit an existing water network in a paper mill that was not originally designed with process integration techniques. Five scenarios are presented, each representing different aspects of decision-making in real process integration projects. The fifth scenario makes use of fuzzy optimisation to achieve a compromise solution that considers the inherent conflict between maximising water recovery and minimising capital cost for retrofit.
The pulp and paper (P&P) industries are classified among the water-intensitive industries. In this work, implementation of the Water Closed-Loop System (WCLS) in a P&P factory to reduce water consumption and wastewater generation was reported. First, the water and steam network of the mill was synthesized, and water sinks and sources along with their flowrates were identified. The key pollutants, including chemical oxygen demand (COD), total suspended solids (TSS), and total dissolved solids (TDS), were pinpointed and acceptable levels for water sinks were acquired. In the second step, by using water pinch analysis with the direct-reuse approach, each limiting pollutant was investigated, and the maximum reduction in freshwater consumption equal to 36.9 % was obtained by considering TSS as the only pollutant. The minimum potential for reducing water consumption belonged to COD (4.0 %) and TDS (18.9 %). In the regeneration-reuse approach, the incomplete performance of the mill's treatment plant in removing COD and TDS resulted in no improvement in the results of the previous step. In the case of TSS alone, the reduction in freshwater consumption increased to 93.3 %. Mathematical optimization was used to study all limiting contaminants simultaneously. The direct-reuse approach achieved a 4.0 % reduction in water consumption, while the regeneration-reuse did not change water consumption compared to the direct-reuse approach, emphasizing the incomplete operation of the treatment plant. Finally, the output contaminants levels of a hypothetical decentralized and modified existing treatment plant were estimated using literature. In this case, the freshwater consumption of the mill declined by 93 %.
Development of water recovery system improves sustainability of industrial water supplies and minimises water cost. This paper proposes an integrated simulation-optimisation approach for the design and optimisation of a water recovery system for a polylactide (PLA) production process. The latter is among the industrial processes that are known for consuming a high amount of water during its operation. In this work, an integrated simulation-optimisation approach is adopted to address water minimisation problem in a PLA production process. A steady-state process simulation software is first used to model the PLA production process, in order to obtain its mass and energy balances, as well as to identify the important process parameters that affect water recovery. The model simplifies the non-linearity of the reactor model, and also determines the relationship between reactor operating conditions with the water source flowrates. Mathematic programming technique is next used to synthesise its water recovery network which involves multiple impurities. Several water recovery scenarios with different optimisation objectives were used for the evaluation, i.e. minimising flowrate (scenario 1), minimising cost (scenario 2) and maximising profit (scenario 3). Both scenarios 2 and 3 that involve process optimisation at the reactor achieve the minimum freshwater and wastewater flowrates, with maximum profitability for the process. As compared with the base case process, the water reuse/recycle scheme for these scenarios leads to extra 34.3% and 17.5% reduction in freshwater demand and wastewater flowrates respectively.
Brine and bittern waste streams are classified as a byproduct of seawater desalination operations, as well as many inorganic industries. As such, many of those industries are challenged to develop and implement sustainable, cost-effective strategies for managing water usage and wastewater discharge. As a result, zero liquid discharge goals have garnered a lot of interest for the purpose of enhancing strategies for wastewater handling. Zero liquid discharge may be achieved using a number of methods, including technologies through which industrial wastewater is reduced to dry solids/salts. This would mostly involve wastewater processing to brine water quality, using standard brine-producing wastewater treatment methods, followed by conventional zero liquid discharge techniques, which in turn transform brine wastewater to salts/bitterns. Salt sludge and bittern waste from zero liquid discharge processing have no adverse effects on the environment. Moreover, many techniques allow for the recovery of extra-purified water streams, as a result of wastewater-to-brine processing, and/or brine-to-salt processing. Recovered water streams may be directly reused, or even utilized to enhance the quality of other wastewater streams before reuse. Since compliance with stringent industrial wastewater regulations is through zero liquid discharge applications, this work discusses the incorporation of zero liquid discharge processing options onto interplant water network synthesis problems. Accounting for the presence of both central and distributed zero liquid discharge processing schemes enables the identification of cost-optimal interplant water networks, when stringent wastewater discharge requirements are imposed. This paper focuses on a specific class of water integration problems, which involve brine management. A case study is used to illustrate the proposed approach and to highlight the importance of accounting for zero liquid discharge considerations, to develop grassroots designs for interplant water networks. For a given industrial city layout, four different scenarios have been carried out, and each case was associated with certain wastewater discharge requirements. As a result, differing optimal interplant water network designs have been attained for each of the cases, which have been investigated.
A multi-period planning approach for water reuse and regeneration networks in Eco-Industrial Parks (EIPs) is presented. The objective of the optimization problem is to determine the lowest network cost design for such systems, by taking into account an entire planning horizon. A source-to-sink mapping approach has been proposed to formulate the multi-period planning problem. Water sources can either be allocated to water sinks, treatment units or discharged to environment. Freshwater streams and treated water are made available to mix with water sinks to enable reuse between plants. Waste water is allowed to be discharged into environment at threshold contaminant levels. The problem has been illustrated initially with two-stage centralized treatment unit, then by considering a hybrid treatment setup consisting of both centralized and decentralized options. The results obtained indicate considerable cost reductions, when compared to those developed separately for each individual period. Moreover, a decrease in the complexity of the water networks has also been observed, when simultaneously considering the entire planning horizon.
Mathematically rigorous methodologies to target the minimum resource requirement for a batch process are proposed in this paper. The proposed methodologies guarantee the minimum resource requirement for single as well as cyclic batch operations. The methodologies are applicable to both semicontinuous and truly batch processes. Based on the rigorous mathematical arguments, it has been proved that, for a single batch operation, targeting through sequential transfer of waste from one time interval to the next time interval always leads to the overall minimum resource requirement. On the other hand, for a cyclic batch process all the time intervals may be collapsed as a single interval and the minimum resource requirement can be targeted directly. The proposed methodology is applicable to any fixed flow rate and fixed scheduled batch process involving a single quality. The applicability of the proposed algorithm is demonstrated through illustrative examples.
There is little hope of an effective solution until the designer knows the amounts of material and energy
moving through the system. The two fundamental tools for making the process analysis are the material balance and the energy balance. A material balance will be needed for virtually every pollution prevention and control problem.
This book explains how to calculate the material balance and the energy balance. Twenty five case studies
and 85 examples explain how these tools are used. The examples include a variety of air, wastewater, and
solid waste management problems and the student will learn a good deal about these areas of engineering
while mastering the design tools. They will also be introduced to some fundamental concepts for chemical
and biological reactions, material separations, and economic evaluations.
The quantitative tools and methods that have been developed to identify and cultivate industrial symbiotic exchanges in existing industrial parks to minimize overall energy and material consumption are reviewed. The issues relevant to adapting an existing park differs from those associated with constructing a new park using eco-industrial principles. Published literature was surveyed for methodologies which identify and establish viable inter-company exchanges for water, heat, power and materials. Studies which address issues associated with infrastructure alterations are specifically highlighted, as well as methods to quantify and manipulate any potential financial and/or ecological benefits gained by adopting proposed eco-industrial measures. Additional topics, such as network analysis, company motivation, confidentiality issues and introduction of new industries or facilities are included. This review surveys current quantitative methodologies that can be applied to the process of adapting established industrial park networks into eco-industrial park systems and case studies which are pertinent to this type of adaptation.
Water is commonly used in the process industries as raw material and utility systems as well as for washing operations. In recent years, stricter environmental regulations and water scarcity issues have led to the growing need for better water management. Concurrently, the development of various process integration tools for resource conservation has become very established in recent years. This chapter presents one of the important process integration tools, known as water pinch analysis, for the design of a water recovery system. A water recovery case study of a steel plant is used for illustration.
Energy recovery within processes via heat exchanger network (HEN) to minimise the external utilities has been well established. Due to the close energy interactions between HEN and the utility system, it is important to synthesise these two elements simultaneously. In this work, a novel systematic approach for synthesis of HEN with utility systems is presented. Multiple cascades automated targeting is applied to determine minimum total operating cost of the trigeneration system, minimum hot and cold utility targets for heat integration prior to detailed design. Besides, the selection and allocation of utilities, distribution of steam, and potential power generation can also be determined. Meanwhile, the types of boiler fuel for the trigeneration utility system is also identified. An illustrative example with two scenarios is solved to illustrate the proposed approach.
Over the past decades, many systematic process integration techniques have been developed for synthesising resource conservation networks (RCNs). Automated Targeting Model (ATM) is one of the approaches that incorporates insight-based concept into mathematical optimisation model to locate various targets for RCNs. However, in order to perform Automated Targeting, the quality values of process sinks and sources must be first identified and arranged in ascending or descending order. Therefore, for cases where the quality of process sinks and sources are given in a range and not fixed, the conventional ATM will not able to locate the targets accordingly. To overcome such limitation, a novel Floating Automated Targeting Model (FATM) is presented in this work. Two literature case studies are solved to illustrate the proposed approach.
Strict environment regulations in chemical and refinery industries lead to minimize resource consumption by designing utility networks within industrial process plants. The present study proposed a superstructure based optimization model for the synthesis of water and hydrogen networks with partitioning regenerators without mixing the regenerated sources. This method determines the number of partitioning regenerators needed for the regeneration of the sources. The number of the regenerators is based on the number of sources required to be treated for recovery. Each source is regenerated in an individual partitioning regenerator. Multiple regeneration systems can be employed to achieve minimum flowrate and costs. The formulation is linear in the regenerator balance equations. The optimized model is applied for two systems, partitioning regeneration systems of the fixed outlet impurity concentration and partitioning regeneration systems of the fixed impurity load removal ratio (RR) for water and hydrogen networks. Several case studies from the literature are solved to illustrate the ease and applicability of the proposed method.
Operating cost of a batch process can be reduced using multiple resources. In this paper, a methodology is proposed to target multiple resources in order to minimize the operating cost of the overall batch process. The proposed methodology is based on the concept of prioritized cost, originally developed for continuous processes. Prioritized cost of a resource depends on the pinch quality, quality of the resource and its cost. The concept of prioritized cost is extended to optimize the operating cost of a batch process. It is proved that to minimize the operating cost a batch process, prioritized cost of a resource in any time interval may not necessarily depends on the pinch quality of that interval. Prioritized cost of a resource in any time interval depends on the highest pinch quality of all the subsequent intervals, including itself. This important result is proved mathematically. The proposed methodology is applicable to fixed-scheduled, fixed-flow batch processes involving single quality.
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.
A new targeting technique is proposed in this work to determine the minimum resource and waste targets for batch process integration problems. The technique, which is generic in nature, handles fixed-schedule batch heat and mass exchange, as well as water networks equally well. Even though the technique is formulated as a mathematical optimization model, the concept, which is built on the insight-based pinch analysis technique, enables the minimum resource/cost targets to be identified prior to detailed design. Five examples are solved to demonstrate the newly developed technique.
Water reuse/recycle has gained much attention in recent years for environmental sustainability reasons, as well as the rising costs of fresh water and effluent treatment. Process integration techniques for the synthesis of water network have been widely accepted as a promising tool to reduce fresh water and wastewater flowrates via in-plant water reuse/recycle. To date, the focus in this area has been on water network synthesis problems, with little attention dedicated to the rare but realistic cases of so-called threshold problems. In this work, targeting for threshold problems in a water network is addressed using the recently developed numerical tool of water cascade analysis (WCA). Targeting for plant-wide integration is then addressed. By sending water sources across different geographical zones in plant-wide integration, the overall fresh water and wastewater flowrates are reduced simultaneously.
This study presents a mathematical optimization model for resource conservation network (RCN) synthesis that includes interception units within the structure of the network. RCNs are the one of the most efficient designs for minimizing fresh water consumption, wastewater generation, and operation cost. Interception units (single pass and partitioning units) are widely accepted industrial application techniques used to reduce network complexity and flow rate targets in RCN. Cost equations relating to the piping and operating costs are added when interception units are designed in an RCN. Then, the problem is formulated as a two stage optimization model whose objective functions are to minimize freshwater consumption and total annualized cost (TAC). The applicability of the developed model is demonstrated with two case studies. Single pass interception units with a fixed outlet concentration (CRout) reduced freshwater consumption by 23.16% and 46.3%, while partitioning units reduced consumption by 21.69% and 29% respectively, when compared to base systems.
Carbon capture and storage (CCS) techniques are considered as one of the promising approaches to reduce carbon dioxide (CO2) emissions from fossil fuel based power generation, which still accounts for a significant portion of greenhouse gas emissions in the world. CCS technology can be used to mitigate greenhouse gas emissions, with the additional advantage that it allows continuing use reliable and inexpensive fossil fuels. However, CCS retrofit entails major capital costs as well as a reduction of overall thermal efficiency and power output. Thus, it is essential for planning purposes to implement the minimal extent of CCS retrofit while meeting the specified carbon emission limits for the power sector. At the same time, it is necessary to plan for compensatory power generation capacity to offset energy losses resulting from CCS retrofit. In this paper, an algebraic targeting technique is presented for planning of grid-wide CCS retrofits in the power generation sector with compensatory power. The targeting technique is developed based on pinch analysis. In addition, the proposed methodologies are illustrated through case studies based on grid data in India and the Philippines. Sensitivity analysis is carried out to determine the suitable CCS technology and compensatory power source which satisfy emission limits.
The objective of this work is to develop an integrated, systematic, and cost-effective design technique to synthesize a resource conservation network. On the basis of different characteristics for the process constraint and environmental discharge limit, mass and property integration techniques are adapted in this proposed approach. A conceptual framework is first developed to serve as the basis of the mathematical optimization model. A mixed-integer nonlinear programming (MINLP) formulation is developed to synthesize a resource conservation network with minimum total annualized cost. A case study on the production of phenol from cumene hydroperoxide is presented to illustrate the proposed approach.
Water scarcity, rising energy costs, and stricter regulations on disposal of industrial effluents have forced a focus on the water usage in process plants. In this context, the development of methodologies to analyze the possibility of water reuse in industrial processes, considering the presence of multiple contaminants, has became an important issue for process engineers. There are a great variety of methods to deal with this problem, and they can be divided in two groups: algorithmic methods and mathematical programming methods. The problem with multiple contaminants becomes more complex, and the available algorithmic procedures are sometimes cumbersome; the methodologies based on mathematical programming present complex formulation and solving algorithms. This paper presents an extension of the algorithmic procedure water source diagram (WSD) to multiple contaminant processes. The proposed extended WSD procedure synthesizes water mass exchange networks for multiple contaminant processes, focusing on water reuse. It also targets the minimum water consumption and simultaneously makes the synthesis of the corresponding water network. The proposed procedure was applied in different examples used in the literature by others authors when discussing their proposals. Confrontation of results shows that the methodology here proposed has very good performance.
The minimization of the water footprint of industrial cities or parks requires the development of efficient water reuse strategies. Current methods for water integration do not consider industrial city planning horizons in the development of optimal water reuse and recycle strategies. This article presents a multiperiod planning approach for water integration within industrial cities. The initial formulation considers direct reuse of water between plants and involves water streams with several pollutants. A source–sink water mapping model was implemented such that available water sources can be either allocated to water sinks or discharged as wastewater streams. Freshwater streams were made available to mix with water sinks as necessary, to enable reuse between plants. The work presents two optimization models to determine the minimum freshwater use in the industrial city through maximum direct water reuse regardless of cost (model 1) and the lowest-cost design for direct water reuse (model 2). Several illustrative examples are presented to demonstrate the proposed methods. The results indicate great potential for achieving considerable savings of resources when integration strategies for plants are developed over an entire planning period rather than individual time periods.
This paper presents a mathematical model for a cost effective minimum water network for intra and interplant involving multiple contaminants for a set of process plants. A generic mixed integer non-linear programming (MINLP) model has been developed based on water network superstructure to targets and design minimum water network for retrofit design. The model includes all levels of the water management hierarchy (i.e. source elimination, source reduction, direct reuse/ outsourcing of external water, regeneration reuse and fresh water) and is set to achieve a payback period criteria set by the designer to ensure cost effectiveness of the solution. The approach is illustrated by using an inter-plant case study involving a semiconductor and a chlor-alkali plant. The results show that the new freshwater and wastewater targets are 14.99 t/hr and 2.94 t/hr respectively with capital cost of USD 276,900 and payback period of 3 years. This represents a 54.90% increment in freshwater reduction as compared to Handani et al [1] and Wan Alwi et al [2].
Purifiers are widely used in refinery hydrogen networks. The placement of purifiers is critical in reducing the utility consumption. Various conceptual methods have been employed to find the optimal placement of the purifier inside the hydrogen network. However, previous research only adopts the performance based purifier model, leaving the mechanism based purifier model behind. More practical and simplified approaches are expected to deal with the complicated mechanism models. This paper improves the existing graphical approach in two aspects: incorporate algebraic equations into graphical methods to find the initial location of purifiers with complicated models; develop a novel pinch sliding approach to simplify the shifting procedure of composite curves. In this method, both performance based and mechanism based models of purifier can be solved. Another advantage of this targeting approach is that the flow rate of streams to the purifier also can be optimized simultaneously. Case studies indicate that this method is effective for both hydrogen and water networks.
System-wide analysis of water systems to minimize water use in process industries has been carried out when charges for effluents from the process are simultaneously considered with cost of freshwater intake and in-house water treatment in the design of water and effluent systems. It has been demonstrated that the degree of wastewater regeneration and recycling is heavily dependent on the charges associated wastewater effluent. The reusability of water and its techno-economic impacts are examined with both a graphic-based manual technique and an automated design method using mathematical optimization, with which conceptual insights are sought in a systematic manner to evaluate different integrated options including water reuse, regeneration and recycling. For the optimization model, new solution strategy has been proposed for solving the MINLP problem of total water systems which carries out rigorous economic trade-offs existed in an integrated water network, together with wastewater charges.
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