Search

Rising energy demand and concern for environmental emissions have encouraged researchers to explore variety of methods for retrofit of heat exchanger networks (HEN). Current graphical and insight-based HEN retrofit methods have some common limitations. Most of the techniques may involve tedious graphical constructions, iterative calculations, or use of multiple diagrams to accomplish HEN retrofit. This paper introduces a new HEN retrofit method called the Individual Stream Heat Cascade Analysis (ISHCA) Technique. Within a single diagram called the Heat Cascade Table (HCT), ISCHA simultaneously show individual hot and cold streams heat allocation, identify the Pinch point and determine the minimum utility requirements to guide HEN retrofit that observes the Pinch design rules. Application of ISCHA technique on an illustrative case study shows reductions of 72 % hot utility and 66 % cold utility from the existing HEN. ISHCA combines numerical precision and efficiency with visualization insights to yield results that are comparable to other retrofit methods. [ABSTRACT FROM AUTHOR]

Heat integration has played an important role in maximising heat recovery, improving energy efficiency and reducing environmental emissions of industrial processes. However, practical aspects of heat integration such as physical distances between pipelines and space constraints must be considered especially during retrofit of heat exchanger networks (HEN). During HEN retrofit, process streams are matched based on their thermodynamic profiles to achieve energy targets. The physical distances between process streams and the space available for heat integration are usually not considered during HEN retrofit even though these issues could offset the cost savings from heat recovery. Matching of process streams across long distances may impose extra piping and pumping costs in order to overcome pressure drop. Pumping cost is also affected by elevation apart from pipeline distance. This work proposes a new graphical tool for visualising the location of process streams as well as the available space within an existing process plant, based on a proposed graphical coordinate representation. With the aid of this graphical tool, process streams can be matched not only based on their thermodynamic profiles, but also by considering the nearest physical distance and elevation of process streams. Designers can also identify the physical locations of additional equipment such as heat exchangers and pumps using the coordinate representation based on a proposed set of heuristics for equipment placement. Pumping and piping costs are included in the capital-energy trade-off analysis. Results of the study show that the coordinate representation of the existing plant can help generate a more practical HEN retrofit design for actual implementation. [ABSTRACT FROM AUTHOR]

Medium and large scale industries typically consume large amounts of energy, and are under pressure to increase energy efficiency and reduce energy wastages. Conventional insight-based heat exchanger network (HEN) retrofit methods typically combine graphical visualisation and algebraic tools to manage different retrofit stages. These stages often involve repetitive calculations of approach temperature, enthalpy balance and heat transfer area to assess the HEN feasibility and cost-effectiveness. This paper extends the individual stream temperature versus enthalpy plot (STEP) methodology that was introduced for HEN synthesis, to HEN retrofit. The STEP retrofit method proposed in this work enables users to simultaneously diagnose and retrofit existing HEN by using only the STEP diagram that maintains the characteristics of individual process streams. Users can graphically perform individual stream mapping without having to calculate stream enthalpies or to check for minimum temperature approach ( Δ T m i n ) violation during retrofit. Application of the new STEP retrofit method on an industrial case study demonstrates its advantages in terms of user interactiveness, simplicity of use, flexibility to customise the methodology to achieve retrofit goals of plant owners, and the least amount of efforts needed to achieve comparable results as those of established retrofit methods. [ABSTRACT FROM AUTHOR]

Carbon dioxide emissions coming from industrial, transport, service and business activities as well as methane and nitrogen oxides from agriculture are major greenhouse gases with high global warming potentials. Modelling tools for the optimal management and reduction of greenhouse gas emissions, in particular, carbon dioxide, have received growing attention. Concurrently, complementary graphical and visualisation tools for carbon dioxide targeting, design and planning based on Pinch Analysis have evolved in line with the developments of other Process Integration tools. The application of Pinch Analysis includes the conservation of resources including heat, mass, water, gas, materials, property, solid, and more recently, power. This paper provides a comprehensive review of the development of Process Integration insight-based graphical, algebraic and numerical tools for carbon dioxide emission reduction. The key focus of the review is on methodologies that are capable of making explicit assessment on, and quantify the impact of the use of the PI tool on CO 2 reduction, covering works from 2007 (when it was initially introduced) until year 2016. The review has been categorised into supply side energy and emission planning as well as demand side and end-of-pipe energy and emission management. The aim of the review is to provide researchers, industrial planners, policy-makers and energy managers awareness of the appropriate insight-based graphical, algebraic and visualisation Process Integration tools that are available for use for carbon dioxide emissions planning and reduction. Applications of such tools is expected to enhance their conceptual understanding of the problems and ultimately help them make better decisions during the planning and management of greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

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

Pressure drop is an important consideration in Total Site Heat Integration (TSHI). This is due to the typically large distances between the different plants and the flow across plant elevations and equipment, including heat exchangers. Failure to consider pressure drop during utility targeting and heat exchanger network (HEN) synthesis may, at best, lead to optimistic energy targets, and at worst, an inoperable system if the pumps or compressors cannot overcome the actual pressure drop. Most studies have addressed the pressure drop factor in terms of pumping cost, forbidden matches or allowable pressure drop constraints in the optimisation of HEN. This study looks at the implication of pressure drop in the context of a Total Site. The graphical Pinch-based TSHI methodology is extended to consider the pressure drop factor during the minimum energy requirement (MER) targeting stage. The improved methodology provides a more realistic estimation of the MER targets and valuable insights for the implementation of the TSHI design. In the case study, when pressure drop in the steam distribution networks is considered, the heating and cooling duties increase by 14.5% and 4.5%. [ABSTRACT FROM AUTHOR]

This paper presents a new technique for simultaneous minimisation of water and energy in process plants through a combination of numerical and graphical tools. The technique consists of three steps, namely, setting the minimum water and wastewater targets; design of minimum water utilisation network, and finally, heat recovery network design. This technique offers two key advantages over current state-of-the art techniques. Firstly, it is applicable to mass transfer based and non-mass transfer based water-using operations. Secondly, it introduces a new graphical visualisation tool through a plot of temperature versus stream flowrate, termed as heat surplus diagram to guide water and energy reduction simultaneously. The heat surplus diagram provide insights on the energy demand as well as on stream matching scenarios during design of a maximum water and energy recovery network. A case study on a paper mill plant demonstrates that significant reductions in water and energy consumption can be achieved using this approach. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a generic graphical approach for simultaneous targeting and design of a utility gas network. The approach has been effectively and interactively used to target the minimum utility gas flow rate and design a maximum nitrogen gas recovery network. A graphical tool known as Network Allocation Diagram (NAD) is introduced to assist designers to graphically visualize, explore, evolve, and systematically select networks that yield either the minimum gas targets or the minimum number of streams. Application of this approach results in a potential reduction of 33.8% fresh gas and waste gas. [Copyright &y& Elsevier]

The Water Cascade Analysis (WCA) technique was used to identify opportunities for reduction in freshwater usage as well as wastewater generation and to assist in the retrofit of an existing paper mill water distribution network. This procedure involves three key steps; i.e., a global analysis of the present water distribution and consumption, setting the baseline minimum water targets using WCA technique and retrofit of water network to achieve the minimum water targets. Notwithstanding the extensive water recycling currently employed in the paper mill, this study identified a potential scope of reducing 13.3% freshwater and 13.3% wastewater. Water reduction represents a total potential annual savings of RM 595,232, taking into account the raw water and wastewater treatment costs, pumping and chemical costs. [ABSTRACT FROM AUTHOR]

Abstract: Development of maximum water recovery (MWR) networks for continuous processes based on Pinch Analysis has been rather well established. In contrast, less work has been done on the water minimisation problem for batch process systems. This work presents a two-stage procedure for the synthesis of an MWR network for a batch process system, covering both mass transfer-based and non-mass transfer-based water-using processes. The first stage of the synthesis task is to locate the various network targets, which include the overall and interval-based minimum utility targets (fresh water and wastewater flows) as well as storage capacity target using the newly developed time-dependent water cascade analysis (WCA) technique. In the second stage, a new tool called the time-water network is introduced to help in the development of the MWR network to achieve the established utility targets. This new network representation has an advantage of clearly depicting the time-dependent nature of a batch water network. [Copyright &y& Elsevier]

Abstract: The first part of this series of papers (Chem. Eng. Sci. 59(5) (2004) 1009) presented a methodology for identifying the minimum utility targets for a mass exchange network (MEN) for a batch process. This paper describes the methodology for setting the minimum number of mass exchange units target and a procedure for designing a maximum mass recovery network that features the minimum utility targets. The time-grid diagram and the overall time-grid diagram that include the time dimension in network design have been introduced to provide a better representation of the mass exchange network for a batch process. The systematic network design procedure also includes a technique to simplify and evolve the preliminary batch MEN to reduce the number of mass exchangers to the minimum. [Copyright &y& Elsevier]

This work presents the water cascade analysis (WCA) as a new technique to establish the minimum water and wastewater targets for continuous water-using processes. The WCA is a numerical alternative to the graphical water targeting technique known as the water surplus diagram. The WCA is to the water surplus diagram in water pinch analysis (WPA) as problem table analysis (PTA) is to the grand composite curves in heat pinch analysis. By eliminating the tedious iterative steps of the water surplus diagram, the WCA can quickly yield accurate minimum water targets, pinch point locations, and water allocation targets for a maximum water recovery (MWR) network, thereby offering a key complementary role to the water surplus diagram in the synthesis of water network. As in the case of the water surplus diagram, the WCA is not limited to mass-transfer-based operations and is applicable to a wide range of water-using operations. [ABSTRACT FROM AUTHOR]

Heat exchanger network (HEN) retrofit plays a major role in solving environmental issues and improving plants' performance. Development of HEN retrofit graphical tools has recently focused on detailed representation of existing HEN to facilitate retrofit problem-solving. This work presents a new customised approach for HEN retrofit that uses a combination of individual stream temperature versus enthalpy plot (STEP) to map hot and cold streams, a heat exchanger area versus enthalpy (A vs H) plot to minimise the required overall heat exchanger area and graphical cost screening tool and strategies to steer and customise a retrofit design toward a desired investment payback period. Application of the new retrofit methodology on a sunflower oil production plant shows comparable energy savings and 20% shorter payback period as compared other established retrofit methodologies. Image 1 • STEP and A vs H plot are employed to perform capital-energy trade-off for HEN retrofit. • STEP indicates the multiple utilities required. • A vs H plot visualises heat exchanger area and number of additional units. [ABSTRACT FROM AUTHOR]

Hybrid power systems are becoming more popular nowadays as they provide a good transition towards renewable energy systems integration while still maintaining power sources from fossil fuels. Uncertainties based on seasonal changes, weather patterns and demand fluctuations have been considered. Disasters such as earthquake, tornado and hurricane are becoming more frequent and unpredictable as climate change is affecting major parts of the world. Safety and resilience are two important aspects that need to be taken into consideration in designing power systems due to the increase in extreme weather and natural disasters. Safety precautions are taken into consideration to withstand major damage and ensure the power system can continue to run smoothly with no or little interruption to the power supply. Previous studies focused on optimizing the cost and efficiency of the system based on season change, weather and demand fluctuations. The purpose of this research is to develop a novel methodology to design a hybrid power system considering resilience and safety aspects. This research primarily focuses on the use of Decision Matrix Risk Assessment Technique (DMRA) and Power Cascade Table (PCT) to evaluate the impact of disasters towards the power systems with and without safety consideration. The results of the case study have shown that the implementation of safety can reduce the total cost by up to USD209.3 M when catastrophic events occur. [ABSTRACT FROM AUTHOR]

Abstract: Supertargeting based on composite curves (CC) is widely used to determine the optimum approach temperature (ΔT min) that yields the minimum total cost for heat exchange networks (HEN). Supertargeting using CC has two key limitations. Firstly, the HEN area calculations are drastically simplified through the assumption that CC segments may be considered as pseudo-single hot and cold streams exchanging heat via only one exchanger that is governed by a single cost correlation. Secondly, the current Supertargeting approach of considering only one hot and one cold utility level may lead to a crude estimation of the total HEN cost and the optimum ΔT min. This work presents the stream temperature vs. enthalpy plot supertargeting (STEPS) method that overcomes these limitations. This paper proves that supertargeting based on CC can lead to up to 50% error in the total cost target and poor ΔT min estimations. [Copyright &y& Elsevier]

Sustainability and Industrial Ecology (IE) are the main drivers of industrial symbiosis (InSys) and eco-industrial parks (EIPs). InSys, therefore, extends the idea of industrial ecology (IE) to the industrial sector by adopting a resource-efficient approach where one firm uses the unused or residual resources (materials, energy, water, assets, logistics, and expertise) of another firm. The aim is to enhance a sustainable and cleaner production in an environmentally friendly way, one in which generation of wastes and emission of greenhouse gases (including CO 2) is minimized. Although previous literatures have investigated existing InSys tools, the utilization of the process integration (PI) tools for InSys design and planning has mostly operated in isolation of each other and thus concentrated on individual resources which makes the it hard for InSys designers to select the best tools. Furthermore, there is a dearth in research on comprehensive and integrated resource optimization, which considers the integration of all resources (such as energy, water, power, carbon and wastes) within InSys simultaneously. Therefore, this study investigated and surveyed available literatures in order to identify and develop a more comprehensive description of InSys tools, through the analysis of related methodologies and applications by integration of various resources optimization tools together for the design and establishment of EIPs. The tools are inclusive of both insight-based Pinch Analysis and mathematical optimization models approaches. The review also conducted a bibliometric analysis of some keywords using Scopus over a span of twenty-two years (1998–2019). Through the insights and understanding gained from the review, designers will be more equipped to make a more informed choice of working tools to utilize. Finally, suggestions were offered on some tools that will enhance the integration of eco-industrial parks to minimize fresh water/wastewater, minimize fuel use and reduce GHGs emissions and the minimization of cooling, heating and power requirements in Total Sites. The review of integrated resource optimization tools is then followed by identifying future research directions and development. Image 1 • Process integration (PI), mathematical optimization (MO) methods and other models are reviewed in this work. • A bibliometric analysis of industrial symbiosis (InSys) concept and tools are conducted. • A better understanding of InSys tools for the design and establishment of eco-industrial parks (EIPs) is enhanced. • A valuable insight for researchers, planners and other stakeholders. [ABSTRACT FROM AUTHOR]

Recent developments of Pinch-based heat exchanger network (HEN) retrofit methodologies mainly focus on improvement of HENs, and much less on seeking opportunities to enhance energy efficiency of processes via process and utility changes. Conventionally, Pinch-based retrofit methodologies employ Composite Curves (CC) and Grand Composite Curve (GCC) to screen for process changes opportunities. However, CC and GCC cannot directly indicate the specific individual process and utility streams to undergo process changes as the streams are composited within the CC and GCC. This work extends the use of individual stream temperature versus enthalpy plot (STEP) to enable designers to scope, screen and selectively customise structural and parametric process and utility changes for existing HENs. STEP diagram can be used to graphically customise retrofit options involving beneficial process utility changes for an existing HEN, and improve overall process energy efficiency. Application of STEP diagram on an illustrative case study and an existing crude oil refinery plant show that STEP diagram enables a designer to graphically pinpoint the exact individual process streams to undergo process and utility changes based on the individual stream profile and to determine the optimal load and levels of multiple utilities required, as well as the limit of process changes that can be performed. Results of this work show that on top of performing HEN retrofit, customised process and utility changes can result in an additional 18.4% hot utility reduction. Image 1 • CC and GCC cannot identify specific individual process stream for process changes. • New methodology uses STEP for structural and parametric changes of existing HEN. • Proposed methodology is applied on an existing crude oil refinery plant. • Additional 18.4% Q H reduction is achieved by process change. • Large savings can be achieved by process change with little or no investment. [ABSTRACT FROM AUTHOR]

The difference in electricity pricing based on the time of power use has led to load shifting from peak to off-peak hours in hybrid power systems (HPS). Apart from optimising electricity cost, shifting of the load may also change the capacity of storage in the system. Power Pinch Analysis has been recently applied to guide load shifting aiming to minimise the cost of electricity, considering the peak and off-peak electricity pricing. The HPS was assumed to be ideal with 100% efficiency, which is not achievable in actual operational condition. This work extends the study by scrutinising the effects of peak-off-peak load shifting on the capacity of storage in HPS. The effects of energy losses due to the inefficiency during power conversion, transfer and storage in the HPS are considered in developing shifting heuristics to ensure optimal storage size is achieved. Implementation of the proposed load shifting strategy on a case study demonstrates that a reduction of up to 30% in the storage size can be achieved, which led to a minimum storage cost. The distribution of peak hours' demand to off-peak hours also successfully provide significant savings in the electricity bill. [ABSTRACT FROM AUTHOR]

Abstract: Total Site Heat Integration (TSHI) is a technique of exchanging heat among multiple processes via a centralised utility system. An analysis of the integrated multiple processes, also known as the Total Site (TS) system sensitivity, is needed to characterise the effects of a plant maintenance shutdown, to determine the operational changes needed for the utility production and to plan mitigation actions. This paper presents an improved Total Site Sensitivity Table (TSST) to be used as a systematic tool for this purpose. The TSST can be used to consider various ‘what if’ scenarios. This tool can be used to determine the optimum size of a utility generation system, to design the backup generators and piping needed in the system and to assess the external utilities that might need to be bought and stored. The methodology is demonstrated by using an Illustrated Case Study consisting of three processes. During the TS normal operation, the Total Site Problem Table Algorithm (TS-PTA) shows that the system requires 1065kW of High Pressure Steam and 645.5kW of Medium Pressure Steam as the heating utility, while for the cooling utility, 553.5kW of Low Pressure Steam and 3085kW of cooling water are required. The results of the modified TSST proposed that a boiler and a cooling tower with the system design requiring a maximum capacity of 2.172MW of steam and 4.1865MW of cooling water are needed to ensure an operational flexibility between the three integrated processes. [Copyright &y& Elsevier]

The hybrid power system (HPS) that integrates diesel/biodiesel plant with renewable energy (RE) technologies has become increasingly popular to alleviate greenhouse gases emissions issue of the sole diesel/biodiesel power system. Integrated diesel-RE power system offers cleaner power supply while minimising cost of diesel fuel and diesel system maintenance. The use of Power Pinch Analysis (PoPA) method for the integration of diesel plants and RE systems into HPS with the objective to minimise fuel requirement and operational time of diesel generator has been presented. This work aims to achieve the same objective via probability theory utilisation, to simplify the PoPA procedure involving the matching of various routes for power flows. The extended technique called the Probability-Power Pinch Analysis (P-PoPA) can give accurate results as those established from the PoPA method within a shorter analysis time because it replaces the tedious manual matching step with correction factors. All probable routes of power from RE and diesel generators to demands are considered in computing the correction factors, in order to target the minimum diesel power in the integrated system. The result of a Case Study demonstrates that 19% saving in diesel fuel consumption can be realised if the present diesel station is supported with renewable solar power in an HPS. The result of the P-PoPA method is accurate with a very minor deviation to that from the conventional PoPA technique. [ABSTRACT FROM AUTHOR]