Total Site Heat Integration Research Articles

Blockchain-based concept for total site heat integration: A pinch-based smart contract energy management in industrial symbiosis

Industrial symbiosis has gained prominence in pursuing sustainable industrial practices, aiming to optimise resource utilisation and reduce environmental impacts. A critical aspect of this endeavour is the efficient management of energy resources within an industrial ecosystem. This paper presents a novel approach to enhance Total Site Heat Integration (TSHI) implementations by employing Blockchain as a facilitator for decentralised energy management. TSHI is an efficient and widely applied method for industrial symbiosis concerning energy flows, which employs the steam mains in site utility systems as the platform for exchanging heat between industrial processes at various temperature levels. It is shown that the synergy of Pinch Analysis and Smart Contract technologies is capable of facilitating energy integration of processes belonging to independent market actors, compared with the currently dominant integration inside a single company. The proposed framework leverages Blockchain as a distributed ledger to enable secure, transparent, and automated energy management across multiple industrial entities in an industrial symbiotic network. The integration of Pinch Analysis principles ensures that the Heat Integration process is optimised to improve the overall energy efficiency. Smart contracts enable automatic negotiation and execution of energy transactions based on predefined rules, minimising the time lag for concluding deals on energy resource exchange and conservation. This paper examines several scenarios to illustrate the implementation of the proposed Blockchain-based TSHI concept within an industrial symbiosis network. It is demonstrated that up to 16 % cost savings are possible by simply enabling transparency via Blockchain. The results could drive innovative development to revolutionise decentralised energy management in a complex industrial ecosystem, especially by synchronising energy exchanges in time.

Total Site Targeting Approach for Heat Recovery at a Paper Factory

The total Site heat integration approach has been used extensively in the industry, including process services and heat exchanger network design integrated with the site service system. This work aims to propose a design for the heat recovery network in the paper factory through Total Site targeting. A procedure that includes the energy analysis and Pinch Analysis methodologies, with the use of Aspen Energy Analyzer is applied. The heat exchanger network design through total site heat integration shows that the rehabilitation of the heat recovery system of the paper machine and boiler blowdown is feasible, with a potential annual saving of 259 t of fuel oil and 116 000 m3 of water, which make it feasible to invest in the factory’s heat recovery system, whose project budget is estimated to recover in a year. Heat exchanger network retrofit design allows to recover 46.2% of the maximum energy recovery.

Multi-Level Process Integration of Heat Pumps in Meat Processing

Many countries across the globe are facing the challenge of replacing coal and natural gas-derived process heat with low-emission alternatives. In countries such as New Zealand, which have access to renewably generated electricity, industrial heat pumps offer great potential to reduce sitewide industrial carbon emissions. In this paper, a new Pinch-based Total Site Heat Integration (TSHI) method is proposed and used to explore and identify multi-level heat pump integration options at a meat processing site in New Zealand. This novel method improves upon standard methods that are currently used in industry and successfully identifies heat pump opportunities that might otherwise be missed by said standard methods. The results of the novel method application suggest that a Mechanical Vapour Recompression (MVR) system in the Rendering plant and a centralized air-source heat pump around the hot water ring main could reduce site emissions by over 50%. Future research will develop these preliminary results into a dynamic emissions reduction plan for the site, the novel methods for which will be transferrable to similar industrial sites.

Novel circularity and sustainability assessment of symbiosis networks through the Energy Quality Pinch concept

Circular Economy is a well-known concept to mitigate global resource depletion issues. The sustainability of a system is closely related to its environmental performance, which is directly linked to energy consumption. This work provides a circularity assessment tool by determining the minimum system energy requirements, according to the Energy Quality Factor, as it indicates the useful energy that can be extracted from material and energy flows. The proposed tool is Energy Quality Pinch Analysis which identifies the minimum energy requirements for a circular system and shows the system's sustainability. The analysis considers cascades of the energy used and released by recycling and symbiosis processes, evaluating the minimal external energy flows: high-quality energy input and waste energy output. The method is applied to case studies, including Total Site Heat and Power Integration, chemical energy reuse in wastewater systems, and Municipal Solid Waste management. Practical energy conversion technologies in each study are proposed as well. The results of the case studies indicate that the degree of energy recovery rate can be as high as 60% for the case of the utility system and higher for the cases of wastewater and municipal waste treatment, providing potentially valuable guidance to system designers.

Total Site Heat Integration in Carbon Neutral Industrial Manufacturing – A Systematic Mapping Study

Foundation Ireland (SFI through MaREI, the SFI Research Centre for Energy, Climate, and Marine and specially the Centre for Doctoral Training in Energy Resilience and the Built Environment (ERBE) (grant no: 12/RC/2302_P2))

Practicable total-site heat integration plan for retrofitting multiple heat exchanger networks

Total-site heat integration (TSHI) is one of effective ways to improve energy efficiency for the process industry. Generally, the existing chemical plants in an industrial park were rarely constructed simultaneously and it is highly possible that each has already been equipped with an optimal heat exchanger network (HEN) at the time when its construction is completed. To further improve the overall performance of the entire site, a novel retrofit design strategy of these HENs is developed in this study using intermediate fluid(s). A two-stage procedure has been adopted to produce a practicable retrofitting plan. Three different revamp strategies are proposed in this work, while any of them can be applied to generate the cost-optimal designs first via indirect interplant heat exchanges. The benefit allocation schemes are then determined according to core and Shapley values in the second stage. The feasibility and effectiveness of proposed methodology are demonstrated in detail with a three-plant example. It is also plain to observe from the corresponding results that the applicability of the aforementioned design strategy is practicable in realistic environment.

Total Site Heat Integration benefiting from geothermal energy for heating and cooling implementations

Geothermal energy is a promising renewable energy source that has been developed by many countries in recent years. It can be utilised to meet various energy demand. This paper studies the performance of integrating geothermal energy in the Locally Integrated Energy Sector (LIES). The heating and cooling demand of various processes should be satisfied, and heat among processes should be recovered. This is done by using Grand Composite Curves and Total Site Profiles to visually illustrate how much load is required for utility systems. The geothermal utility system and steam utility system are compared. The integration plan for geothermal energy under different temperatures are studied. An illustrative case shows that by using this type of renewable energy under a specific and favourable condition, above 70% of steam utility load can be saved. The working cycle of using a geothermal utility system is studied by using the Time Slice model. The heat recovery plan for normal operation, mineral scaling, and cleaning periods are optimised. The minimum temperature for heat storage can also be identified.

Integration of LiBr/H2O Absorption Heat Pump and Absorption Heat Transformer in Total Site Heat Integration

Energy efficiency is one of the main solutions to reduce CO2 emissions in the energy sector and improve primary energy intensity. Energy savings are at the centre of the numerous advantages of energy efficiency and connect to many other economic, social and environmental advantages. Total Site Heat Integration (TSHI) was introduced to maximise the heat recovery from various processes through a centralized utility system. Heat pump using absorption cycle has been identified as one of the waste heat recovery techniques. The challenges of heat pumps applications include limited temperature applications and long payback periods. However, these problems can be tackled by proper design and suitable types of heat pumps considerations. This paper integrates two different kinds of absorption cycle heat pump which are absorption heat pump (AHP) and absorption heat transformer (AHT) into the context of TSHI. This integration is able to reduce the industrial waste heat and generate quality steam. The heat generation of AHP and AHT are estimated based on the enthalpy of working fluid pair of water-lithium bromide. A case study is done to compare and verify the proposed methodology. Economic analysis is performed to compare the different integration approaches of AHP and AHT. Results showed that the integration of hybrid AHP and AHT contribute to the highest annual saving (21,351 USD/y) of utility cost compared to 12,356 USD/y for AHP system and 9,119 USD/y for AHT system.

Absorption Cycle Heat Pump Integration for Locally Integrated Energy Sector

Energy losses in daily life has caused energy inefficiency whereby contributed to serious environment impacts such as carbon emission, greenhouse effect and global warming. The increasing of greenhouse gases emission and crude oil usage have become a main focus to improve world energy efficiency. In order to minimizing the emissions and environmental pollution, Process Integration (PI) through Pinch Analysis (PA) is used to increase the energy efficiency. Total Site Heat Integration (TSHI) is integrated several processes with the centralized utility system. TSHI is extended to Locally Integrated Energy Sectors (LIES) whereby it provides energy integration with end users from various sectors such as the industrial, services, residential, agriculture, transportation and public sectors within a local area, as well as the integration of renewable energy sources. In order to handle the intermittent steams, energy storage is proposed for recovering energy across time period. In this study, waste heat recovery system by using absorption cycle heat pump is highlighted. Two types of absorption cycle heat pump such as absorption heat pump (AHP) and absorption heat transformer (AHT) are used to integrate with LIES utility system to maximize the energy recovery. This new methodology deals with the amount of AHP and AHT heat generation from the enthalpy of working fluid pair in water-lithium bromide with heat storage system in LIES. An illustrative case study is performed for demonstrating and verifying the proposed framework, whereby waste energy recovery opportunities are found from the system studied. Economic analysis on payback period is also performed to compare with the system with and without usage of AHP and AHT. This developing methodology provides a better guidance to engineers especially during the design stage on the performance limitations and specific compromises within a system. At the end of this research, cost saving is achieved, a shorter payback period than existing system and overall energy efficiency is improved within heat storage system for LIES by adding in the absorption heat pump cycle.

Total Site Heat and Power Integration for Locally Integrated Energy Sectors

Maximising energy efficiency is essential for an energy system based on renewable or non-renewable energy sources to minimise fuel demand. Process Integration methodologies for specific energy types (thermal and power) have been well developed in recent years for enhancing energy efficiency. However, the interaction between different types of energy (thermal and power) within a single system could be more deeply studied to achieve the ultimate goal of maximising energy and exergy efficiency. This research work extends the previously developed Locally Integrated Energy Sector (LIES) concept, which integrates the energy systems (thermal and power) of industrial, commercial and residential buildings with thermal energy storage and batteries. The LIES concept aims to reduce overall energy consumption and to enhance overall energy efficiency and power cogeneration. In the present paper, a comprehensive targeting framework is introduced for designing and optimising a combined energy system using a Process Integration (i.e. Pinch Analysis) approach. Steam turbines connect the thermal and power systems, which, in this case, the turbines generate power from waste heat. The on-grid and off-grid power supply options are also considered in this framework. The case study concludes that the lowest energy cost system requires a heat storage systems with let-down in between, power cogeneration from waste heat (i.e. surplus heat below the TS Pinch), Power Pinch Analysis, battery storage and on-grid power supply. The results for the case study show that the overall energy cost of the optimised system is 52% lower than the base case without integration. In this energy system, however, it has been found that the increment of energy efficiency for the steam (thermal energy) system might lead to lower overall energy efficiency and higher total operating cost. This situation happens when there is a lower amount of waste heat available.

Sequential Thermal and Power Integration for Locally Integrated Energy Sector

Energy Efficiency is aligned with the United Nation Sustainable Development Goal for ensuring access to affordable, reliable, sustainable and modern energy for all. Locally Integrated Energy Sector (LIES) concept is introduced for energy conservation between industrial, service and residential sectors. The LIES concept extended the Process Integration technique for energy recovery between multiple process plants through the utility system, known as Total Site Heat Integration (TSHI). However, the development of LIES techniques is divided into two main directions, which are heat and power energy integration. This paper introduces a sequential approach for integrating the heat and electricity system in a LIES. The optimization is done based on time frame, which Time Slices (TSLs) are identified based on drastic changes in heat and electricity supply and demand. The heat system is first analysed by TSHI techniques, which the heat excess and demand are determined. The excess and demand is then used for cogeneration opportunities estimation, which the backpressure and condensing turbine are used. The potential power generation estimated then included to analyse the electricity system using Power Pinch Analysis tools. The use of heat and power storage system are also included in the study, for assessing its impact on the LIES’s energy efficiency. The study considered on- and off-grid power supply system to satisfy the power demand of the system. This proposed heat and power optimisation framework aims to select a system configuration with minimal energy cost.

Total Site Utility System Structural Design Using P-graph

This paper explores the macro optimisation decisions of energy sources selection and the structural design of the utility system within the framework of Total Site Heat Integration (TSHI). Most TSHI research on utility systems focuses on optimisation of conventional Combined Heat and Power systems. To build a new Utility Systems Planner (USP) tool, P-graph has been selected as the optimisation tool. A critical element of USP is the inclusion of low-grade heat utilisation technologies within the considered superstructure. The USP outputs include the optimal structure of the utility system including the arrangement and size of each component and estimates for Greenhouse Gas and Water Footprints. The successful application of the USP to a representative industrial case study with district energy integration shows an optimal solution with a natural gas boiler, reciprocating gas engine, condensing economiser, steam turbine, thermocompressor, organic Rankine cycle, cooling tower, and electric chiller with a total cost of 14.893 M€/y. The new tool is a platform for launching further research including site-specific application, multi-period optimisation, and sensitivity analysis.

Total Site Heat Integration Considering Optimum Pressure Drops

In this study, a new methodology is developed for Total Site Minimum Energy Requirement (MER) targeting, in which optimum stream pressure drops ((Ps) are considered for each individual process. To validate the accuracy of the methodology, two Total Site (TS) systems comprising processes A and B and processes C and D are selected and evaluated using two different approaches; I) considering streams’ assumed heat transfer coefficient (conventional method) and II) considering streams’ allowable (Ps. In the second approach, the possibility of pumps/compressors replacement is first investigated for each individual process, through exploring a 3-way trade-off between energy consumption, area requirement and hydraulic system. The resulting data are then used to construct a Total Site profiles (TSPs) for MER targeting. These profiles depict that the hot and cold utility values, when (Ps are optimized, are much less than those obtained in conventional method using assumed coefficients. Moreover, the TS energy targets that are estimated in this method are more realistic and compatible with the results of detailed design stage.

Cogeneration optimisation for locally integrated energy systems

Energy Efficiency is proven to be a significant opportunity for industry, cities and society, in general, to save energy costs and harmful gaseous and particulate emissions. Locally Integrated Energy System (LIES) was introduced to promote symbiosis between industry and local area to enhance their overall system energy efficiency. LIES extends Total Site Heat Integration (TSHI) to optimise the energy system for multiple industrial processes as well as other process heat demands in proximity. This paper integrates the TSHI methodology with Power Pinch Analysis (PoPA) to sequentially optimise the thermal and electrical energy in a LIES. A Power Cogeneration Estimation Table is used to systematically identify and determine the amount of power that the thermal energy system potentially generates via backpressure and condensing steam turbines. This work evaluated the thermal and power system based on total utility cost, where the thermal requirement is fulfilled by the industrial boiler system with the potential of outsourced power demands. A case study is performed for verifying the proposed methodology. Results found that LIES with Heat and Power Integration and battery storage is recommended for low utility cost operation without the need for a heat storage system.

Design of Robust Total Site Heat Recovery Loops via Monte Carlo Simulation

For increased total site heat integration, the optimal sizing and robust operation of a heat recovery loop (HRL) are prerequisites for economic efficiency. However, sizing based on one representative time series, not considering the variability of process streams due to their discontinuous operation, often leads to oversizing. The sensitive evaluation of the performance of an HRL by Monte Carlo (MC) simulation requires sufficient historical data and performance models. Stochastic time series are generated by distribution functions of measured data. With these inputs, one can then model and reliably assess the benefits of installing a new HRL. A key element of the HRL is a stratified heat storage tank. Validation tests of a stratified tank (ST) showed sufficient accuracy with acceptable simulation time for the variable layer height (VLH) multi-node (MN) modelling approach. The results of the MC simulation of the HRL system show only minor yield losses in terms of heat recovery rate (HRR) for smaller tanks. In this way, costs due to oversizing equipment can be reduced by better understanding the energy-capital trade-off.

Organic rankine cycle and steam turbine for intermediate temperature waste heat recovery in total site integration

The utilization of waste heat for heat recovery technologies in process sites has been widely known in improving the site energy saving and energy efficiency. The Total Site Heat Integration (TSHI) methodologies have been established over time to assist the integration of heat recovery technologies in process sites with a centralized utility system, which is also known as Total Site (TS). One the earliest application of TSHI concept in waste heat recovery is through steam turbine using the popular Willan’s line approach. The TSHI methodologies later were extended to integrate with wide range of heat recovery technologies in many literature, whereby Organic Rankine Cycle (ORC) has been reported to be the one of the beneficial options for heat recovery. In general, the medium to high temperature waste heat is recovered via condensing/backpressure steam turbine, whereas ORC is targeted for recovering the low temperature waste heat. However, it is known that condensing turbine is also able to generate power by condensing low grade steam to sub-ambient pressure, which is comparable with ORC integration. In this work, the integration of ORC and condensing turbine are considered for a multiple-process system to recover intermediate temperature waste heat through utility system. This study presents a numerical methodology to investigate the performance analysis of integration of ORC and condensing turbine in process sites for recovering waste heat from a centralized utility system. A modified retrofit case study is used to demonstrate the effectiveness application of the proposed methodology. The performance of ORC and condensing steam turbine are evaluated with the plant total utility costing as the objective function.

Analyzing the Energy Consumption, GHG Emission, and Cost of Seawater Desalination in China

Seawater desalination is considered a technique with high water supply potential and has become an emerging alternative for freshwater supply in China. The increase of the capacity also increases energy consumption and greenhouse gases (GHG) emissions, which has not been well investigated in studies. This study has analyzed the current development of seawater desalination in China, including the capacity, distribution, processes, as well as the desalted water use. Energy consumption and GHG emissions of overall desalination in China, as well as for the provinces, are calculated covering the period of 2006–2016. The unit product cost of seawater desalination plants specifying processes is also estimated. The results showed that 1) The installed capacity maintained increased from 2006 to 2016, and reverse osmosis is the major process used for seawater desalination in China. 2) The energy consumption increased from 81 MWh/y to 1,561 MWh/y during the 11 years. The overall GHG emission increase from 85 Mt CO2eq/y to 1,628 Mt CO2eq/y. Tianjin had the largest GHG emissions, following are Hebei and Shandong, with emissions of 4.1 Mt CO2eq/y, 2.2 Mt CO2eq/y. and 1.0 Mt CO2eq/y. 3) The unit product cost of seawater desalination is higher than other water supply alternatives, and it differentiates the desalination processes. The average unit product cost of the reverse osmosis process is 0.96 USD and 2.5 USD for the multiple-effect distillation process. The potential for future works should specify different energy forms, e.g. heat and power. Alternatives of process integration should be investigated—e.g. efficiency of using the energy, heat integration, and renewables in water desalination, as well as the utilization of total site heat integration.

Transshipment Type Model for Total Site Heat Integration Using Non-Isothermal Utility Loop

There is a growing interest in developing Total Site Heat Integration methods, since Total Site Heat Integration offers an energy-saving opportunity across multiple plants beyond the traditional intra-plant plant integration. Total Site heat integration can be achieved indirectly by non-isothermal utility loop, such as hot water and thermal oil. The parameters of non-isothermal utility loop, interconnectivity patterns directly determine the energy saving and the capital cost. In this work, a transshipment type Total Site heat exchanger network (HEN) model using non-isothermal utility loop is developed. A new representation method of non-isothermal utility loop is proposed based on transshipment type HEN model to avoid non-linear terms. The model is formulated as a MINLP problem with all linear constraints. The operating cost, capital cost of heat exchangers, pumping and piping cost are holistically considered and optimized. The case study demonstrates the effectiveness of the proposed model.

Utility Exchanger Network synthesis for Total Site Heat Integration

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

Total site heat integration of multi-effect evaporators with vapour recompression for older kraft mills

This paper aims to apply Total Site Heat Integration (TSHI) to appropriately integrate Mechanical and Thermal Vapour Recompression with multi-effect evaporators at older Kraft Mills, to cause a step reduction in fossil fuel use and its associated emissions. Heat and power demands for older Kraft Mills are chiefly satisfied from Recovery Boilers (RB), heavily supplemented by biomass/fossil fuel boilers, and integrated with steam turbines. Prior to firing, black liquor – the RB fuel – is concentrated from about 18 % to 67 % in a multi-effect evaporator, which demands 20 % of site-wide thermal energy. With access to renewable electricity, this study finds that vapour recompression can be economically integrated into a multi-effect evaporator at older Kraft Mills. The vapour recompression configuration with the greatest economic potential used 2-stages of mechanical vapour recompression and 1-stage of thermal vapour recompression. This system achieved a levelised profit of NZD 8.56 M/y, a payback period of 1.0 y and an internal rate of return of 103 %. An optimum integrated set-up needs to account for site-specific heat demand and utility supply profiles through TSHI.