Resource Conservation Networks Research Articles

Stochastic Pinch Analysis to address multi-objective resources conservation problems with parametric uncertainties

An emphasis on sustainable growth helps decrease the initial capital and reduce the impact of industry on an ecologically sensitive environment through resource conservation. Pinch Analysis serves as a valuable tool to identify the potential for resource conservation, waste minimization, and resource costs. However, there are inherent uncertainties associated with these resource conservation networks. The concept of Pinch Analysis is broadened to multi-objective resource conservation problems incorporating parametric uncertainties in this paper. The objective functions are combined to form a single compound objective function using the weighted sum approach. For the compound objective function, prioritized sequences (or resource combinations) are generated through multi-objective prioritized costs to accommodate parametric uncertainties. The multi-objective prioritized cost vs. weights curve helps determine the unique prioritized sequences for different range of weights to achieve optimal solutions. An exact analytical expression for the maximum number of prioritized sequences is also derived. Furthermore, a method is presented to construct the complete Pareto-optimal front to represent all optimal solutions graphically. Two illustrative examples, the hydrogen conservation problem with two objectives (cost and emission) and the water conservation problem with three objectives (cost, land requirement, and emission), demonstrate the proposed method’s utility and efficacy.

Optimizing Resource Conservation Networks: Overcoming Barriers with Process Systems Engineering

Climate change continues to be the major environmental challenge of this century. Some of its effects may include more severe weather conditions, increased incidence of water scarcity, and the potential of pandemic outbreaks, to name a few. Scientific research has thus looked into various strategies to address this problem. These include reducing the generation of greenhouse gas emissions (GHGs) through the implementation of low carbon technologies and transitioning towards a more circular economy through improved resource efficiency. The challenge is in identifying which among the available options would yield the best results. The field of process systems engineering (PSE) which is a computational branch of chemical engineering, provides rigorous methods for analyzing systems which can be used to support decision making. These methodologies have been implemented at various scales to identify strategies which can improve the environmental performance of industrial systems. It has been utilized for optimizing operations of industrial processes, managing resources in eco-industrial parks, greening the product supply chain, and even analyzing strategies for reducing national carbon emissions. This work provides an overview of how PSE tools can be utilized for the design of more sustainable systems and showcases how it can be used at various levels of implementation.

Optimising Segregated Resource Conservation Network with Cross-Zonal Transfer for Multiple Resources and Qualities

Manufacturing industries are continually looking for resource conservation to achieve market competitiveness along with minimum waste discharge for environmental and societal responsibilities. Cooperation between industries to achieve resource sharing through reusing and recycling strategies play a vital role in optimising overall resource consumption, striving towards optimal industrial or urban symbiosis. This paper aims to apply the optimisation framework in a constrained source-sink network considering multiple zones. A special type of constrained resource conservation network, known as segregated targeting problem with dedicated sources and external resources, is considered. The problem contains a set of zones with their own sources and demands and a dedicated resource specified for individual zones. A set of internal sources, freely available for reuse, and external resources are shared among all the zones. In this work, multiple quality constraints that are restricting the allocation of the resources are considered. Unutilised dedicated sources from one zone are reused in other zones through different piping connections with a certain cost associated with it to maximise the utilisation of available sources. The objectives are to minimise the overall resource intake and the total cost for the whole network. This framework enables the selection of optimum zonal integration that yields the optimal cost or maximum resources recycling rate. The distinctive nature of zonal segregation, considering source sharing and multiple qualities, widens the scope of applicability of this approach. The method can be applied to various problem domains, such as regional material recovery networks, sector-wise energy planning, and financial planning.

Extension of pinch analysis to targeting and synthesis of water recycling networks with multiple contaminants

An extended targeting and synthesis procedure using the Pinch approach has been developed for material resource conservation networks with multiple contaminants (e.g. water recycling network with multiple constraints). The Sink and Source Composite Curves (CC) are constructed for each contaminant (load vs flowrate). In this work, a 'polygon' rule is introduced for the CCs representation that illustrates the feasibility of the source mixing. The Source CCs for all the contaminants have to be shifted at least until a 'polygon' is formed around the vertices of the Sink CCs, with lines represent the edges of the Source and Sink CCs. The framework first identifies a freshwater target for each sink with Pinch Analysis based on the pre-determined source arrangement. A condition for further reduction of the freshwater is then checked with the proposed algorithm. Pinch Analysis of each sink sequentially enables the freshwater target and the optimal network design with allocated sources flowrates to be determined.

Cost-optimal Pinch Analysis for sizing of hybrid power systems

Adverse effects of conventional fossil fuel based power generation create an urge for clean technologies. Technologies related to the advancement of renewable energy and clean technologies are growing very fast. Development in renewable energy technologies, reliability and environmental restrictions generates the requirement of a Hybrid Power System (HPS). Cost is an essential factor which plays important role while planning any system. This factor can be included in planning an HPS via Pinch Analysis through the concept of prioritization. This concept is a well-established technique in Process Integration for designing cost-optimal resource conservation networks for various resources such as thermal utilities, water and carbon. However, its application towards the cost-optimal planning of an HPS is still to be explored. In this paper, a methodology is developed to set cost optimal targets in HPS. The proposed methodology extends the concept of prioritization towards planning of cost-optimal HPS. The capital cost of power generation depends on the type of power resource. The proposed method incorporates entry and exit on the time horizon of each power resource. The methodology presented in this paper calculates the power rating of power resources in an HPS required for satisfying the power demands with an objective to minimize the overall cost of electricity. The methodology is illustrated via two examples where 7.75% and 8.8% cost reduction potential are estimated.

Enhanced Cascade Table Analysis to target and design multi-constraint resource conservation networks

Process Integration tools have served the process industries by identifying resource conservation solutions that minimise process waste, reducing the environmental impacts and costs. For dealing with water and wastewater minimisation, Pinch-based targeting and network design approaches are well established to handle single-quality water conservation problems. The Cascade Table Analysis, which has been an extension of the method used for targeting and designing single-quality material recycling networks, has evolved to handle multiple qualities. Based on previous analysis, multiple cascades with individual contaminant/quality indicators are analysed sequentially. Each contaminant is assigned a cascade table. Each sink is classified into the proper contaminant cascade based on their limiting contaminant, and the sources are prioritised based on the contaminant. This work also proposes a new way of arranging the Cascade Table streams to adapt for the multiple contaminants, which is by determining whether they belong to the high quality (Below the Pinch) region and the probable Pinch-causing source. The overall framework has been first identifying preliminary resource targets for each sink, followed by specific heuristics for additional reduction of the fresh resource. The proposed algorithm could yield an accurate minimum resource target and the associated network design. This work also explores the water-using processes with fixed load and fixed flowrate operations. An illustrative study and a real case study from a Brazilian paper mill are used to demonstrate the approach. The fresh water resource identified for the case study is 2,822 kg/h. The developed approach provides an informative interface to the user for the exact allocation of sources to the sinks. The numerical approach also shows directly the location of the Pinch Point(s), the overall fresh resource intake and the waste generation.

Interval Pinch Analysis for Resource Conservation Networks with Epistemic Uncertainties

Pinch Analysis helps in achieving sustainable development through conserving resources in various source-sink resource conservation networks. Diverse applications and methodologies of Pinch Analysi...

Stochastic Pinch Analysis To Optimize Resource Allocation Networks

Pinch analysis is a physical insight-based optimization technique, applicable to conservation problems for a wide range of resources (such as energy, water, hydrogen, cooling water, etc.). Principally, it has been applied to optimize the external resource, to satisfy unmet demands in source-sink allocation problems, with deterministic flows and deterministic quality parameters (such as contamination concentration in water and hydrogen conservation problems). However, in many applications, quality and flow parameters of different sources may not be deterministic due to changes in environmental as well as operational conditions (e.g., changes in product mix and/or feed characteristics). In this paper, the applicability of pinch analysis has been extended to resource conservation networks with uncertain qualities and flows for the operation of individual sources and demands with the desired reliability. The uncertainties in source quality and source flows are incorporated through different probability distri...

Systematic retrofit procedure for resource conservation network based on pinch analysis technique

Over the past two decades, various process integration tools have been developed for the synthesis of material resource conservation network (RCN), ranging from pinch analysis and mathematical programming techniques. Note, however, that most of these techniques were developed for grassroots design problems. In other words, the process plants are still at the design stage where the RCN does not exist yet. The grassroots design techniques are not directly applicable for existing process plants that are in operation. For the latter, some degrees of resource conservation may have been in place, though the RCNs of these process plants may not be designed systematically. Hence, this calls for the development of a systematic retrofit procedure in order to reduce both fresh resource and waste discharge flowrates for the process plants. In this work, a three-step procedure based on pinch analysis is proposed for the retrofit of existing RCNs, focusing on direct reuse/recycle scheme for single contaminant problems. A new analysis tool known as the load–flowrate diagram is proposed for the analysis of impurity load received by the material sinks. This tool helps to identify suitable sinks where unutilised sources may be recovered to. Besides, a revised nearest neighbour algorithm is proposed for the revamping of sink-source matches in the RCN. Several literature examples involving water and hydrogen networks are solved to elucidate the newly proposed procedure.

A Source-Sink Model for Assigning Construction Firms to Projects During Urban Rebuilding

Urban rebuilding efforts in the aftermath of destructive events such as natural hazards or war invariably require allocation of scarce resources to multiple projects that run concurrently. In such scenarios, the construction firms available in a geographic locality may have insufficient capability to cope with the scale of all the rebuilding projects. In such cases, construction firms from outside of the immediate region, but with the required capabilities, may be needed to supplement local capacity. Use of such external capacity incurs additional financial and environmental penalties (e.g., carbon footprint) due to the need to transport heavy equipment, supplies and labor over greater distances. As such, it is necessary to maximize the use of locally available firms, and hence to minimize the need for external ones. The problem is conceptually similar to the optimization of Resource Conservation Networks (RCNs), and lends itself to being solved via Process Integration (PI) approaches. In this work, a source-sink model is developed to optimize the assignment of construction firms to multiple concurrent projects taking place during a concerted urban rebuilding campaign. The model is formulated as a Mixed Integer Linear Program (MILP) whose objective function is to minimize total carbon footprint during urban rebuilding. This carbon footprint is proportional to the project cost and the distance of the construction firm’s headquarters to the city where urban rebuilding is needed. A semi-hypothetical case study on urban rebuilding in the southern Philippines is used to illustrate the application of the model.

Development of an Integrated Technique for Energy and Property Integration in Batch Processes

This paper presented a new technique for targeting minimum total annual cost of property-based heat integrated resource conservation networks (HIRCNs) for batch processes. This new technique takes in consideration of simultaneously heat and property integration with an objective to minimize the usage of fresh resources and energy utilities prior to the detailed network design. It is formulated as a mixed integer nonlinear programming (MINLP) mathematical model for HIRCNs which consists of property-based resource conservation network (RCN) and heat exchanger network (HEN) models. The property-based RCN model is formulated based on a supertargeting approach while the HEN model is developed via automated targeting approach. Two case studies were used to demonstrate the proposed model’s applicability and advantages. Moreover, comparisons of the results for the proposed model for HIRCN with storage system and without storage system as well as sequential targeting approach are also addressed.

Synthesis of Material Interception Networks with P-Graph

A P-graph model was recently developed for direct reuse/recycle scheme for both in-plant resource conservation networks (RCNs) and inter-plant RCNs (IPRCNs). The proposed P-graph model allows visualization which expedites the assessment of optimal and near-optimal solutions. In this paper, the P-graph model will be extended to material interception schemes, i.e., material regeneration and pre-treatment. Material regeneration involves the use of purification unit for quality improvement of the process sources before they are reused/recycled to the sinks. Pre-treatment processes, on the other hand, involve the purification of fresh resources for use in processes with stringent quality requirement. Two literature case studies are solved to demonstrate the newly extended model.

Pinch Analysis of Sugarcane Refinery Water Integration

Water is one of the key resources for the normal life and is used extensively in many industries. The sugar industry is one of the largest water users and producers in food processing sector. This paper presents the analysis of freshwater used and wastewater discharged in a sugar manufacturing process. Also, this paper presents an analysis of cooling water system. The part of the barometric condenser, mill turbine and electric power turbine units were chosen for analysis and synthesis of cooling water systems. In order to reduce the load of the cooling water system, the system was modified to an open recirculation cooling water system. The analysis used water pinch analysis method and mathematical optimization techniques by resource conservation networks spreadsheet software. Analysis of sugarcane hot water balance shows that the water content of sugarcane itself is more than sufficient for internal processing. Analysis of the excess condensate internal water and the discharged water from cooling water system showed that the quantity of freshwater used for cooling system requirement is 121 t/h and the wastewater generation is 24.93 t/h when using BOD as a contaminant.

Synthesis of Resource Conservation Networks with P-Graph Approach—Direct Reuse/Recycle

The need for climate change adaptation in industry has led to intensified research in industrial resource conservation, as well as waste reduction, to enable sustainable operations to be achieved even under conditions of declining water resources. Such sustainability initiatives can be facilitated using the systematic approach of process integration (PI). Of particular interest are resource conservation network (RCN) problems, which have been solved using pinch analysis or mathematical programming methods. On the other hand, other process system engineering (PSE) tools such as the process graph (or P-graph) framework offers potential alternative approaches to RCN problems. To date, P-graph methodology has been used for various process network synthesis (PNS) problems; however, no RCN synthesis applications have been reported thus far. This paper presents a novel implementation of P-graph for RCN synthesis. In addition to the inherent computational efficiency of its algorithms, P-graph allows the elucidation of optimal and near-optimal solutions, a feature which is potentially useful for practical decision-making. Capital and operating cost considerations can be incorporated easily. In this paper, direct reuse/recycle scheme is applied for in-plant RCN and inter-plant RCN (IPRCN).

Automated targeting model for aggregate planning in production and energy supply chains

Aggregate planning aims to maximize profit for a supply chain while satisfying its demand. In this work, the automated targeting model (ATM) that was originally developed for resource conservation network is extended for use in aggregate planning for production and energy supply chains. The ATM is an optimization framework that is based on the insight-based technique of pinch analysis, with the philosophy in setting target(s) ahead of detailed planning. Being an optimization framework, the ATM offers other advantages than conventional pinch analysis technique by incorporating more case-specific constraints, and is able to handle more complex optimization problems. Three literature examples and an industrial polymer production case study are solved to show the robustness of ATM.

Floating Automated Targeting for Resource Conservation Networks

Over the past decades, many systematic process integration techniques have been developed for synthesizing resource conservation networks (RCNs). Automated Targeting Model (ATM) is one of the approaches that incorporates insight-based concept into mathematical optimization 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.

A two-stage optimization approach for the synthesis of resource conservation networks involving interception units

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.

Improved Ternary Diagram Approach for the Synthesis of a Resource Conservation Network with Multiple Properties. 2. Regeneration Reuse/Recycle

Environmental sustainability, rising cost of raw materials, and increasingly stringent emission legislation have motivated process industries to search for resource conservation alternatives. Process integration has been proven to be an effective technique for the synthesis of resource conservation network (RCN). In this first part of the series, the earlier developed clustering technique and ternary diagram by El-Halwagi et al. (AIChE J. 2004, 50 (8), 1854–1869) are extended for the synthesis of RCN with multiple properties. An analytic hierarchy process (AHP) is newly introduced to determine the quality ranking of the sources and sinks, which provides the basic information for the synthesis of RCN. In addition, the mean normalization approach (MNA) is proposed to normalize the property operators to avoid the possibility of the dimensionless property operators being in large magnitude difference when the property operators are divided by randomly selected reference values. Besides, the available region (...

Improved Ternary Diagram Approach for the Synthesis of a Resource Conservation Network with Multiple Properties. 1. Direct Reuse/Recycle

Improved Ternary Diagram Approach for the Synthesis of a Resource Conservation Network with Multiple Properties. 1. Direct Reuse/Recycle

Synthesis of Resource Conservation Networks in an Integrated Pulp and Paper Biorefinery

Pulp and paper production consumes a large amount of water and steam. In particular, water is used in brown stock washing system (BSWS) to separate spent white liquor from the pulp stream. The wastewater stream generated from BSWS, known as black liquor, is a potential biomass. In the current practice, black liquor is concentrated and burned in a recovery boiler to produce steam and electricity. However, recent development in an integrated biorefinery offers increased marketability in pulp and paper mills through the generation of both bioproducts and bioenergy. It is common practice for steam generated from the combustion of black liquor to be integrated with pulp and paper mill to satisfy its heating demands. Note that the water consumption in BSWS directly affects the quantity and quality of black liquor. This will later affect the potential for steam generation and integration in pulp and paper mill. Thus, in this work, water and heat integration is performed for a pulp and paper mill with biorefinery. An integrated pulp and paper biorefinery (IPPB) is proposed which accounts for different conversion pathways of pulp and paper mill biomass. Apart from combustion, several gasification pathways are considered. A nonlinear program (NLP) is formulated to synthesize an optimum IPPB with maximum resources conservation. Sensitivity analysis is then carried out based on the most significant parameters to analyze the robustness of the proposed IPPB.