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Denna studie undersöker integrationen av alkaliska koldioxidavskiljningssystem i naturgaseldade kombikraftverk (NGCC) som en del av insatserna för att minska koldioxidutsläpp från kraftverk baserade på fossila bränslen. Målet är att förbättra den miljömässiga hållbarheten genom att avsevärt minska koldioxidutsläppen och därmed bidra till globala insatser mot klimatförändringar. Forskningen omfattar en grundlig analys av viktiga driftparametrar, inklusive förhållandet mellan vätska och gas (L/G) för NaOH-lösning till rökgas i absorbersektionen, NaOH-koncentration, absorbertryck, flödeshastighet för absorbent och temperaturer för både absorbent och rökgas. Känslighetsanalyser genomfördes genom att variera dessa parametrar för att förstå deras påverkan på CO2-uppfångningsgraden. Utvärdering av nyckelprestandaindikatorer (KPI), inklusive CO2-uppfångningsgrad, lean och rich loading, samt den elektriska effektiviteten hos NGCC-kraftverket, baserades på basfallsscenariet. Dessutom användes pinchanalys för att optimera värmeintegration inom systemet, vilket minskar behovet av extern uppvärmning och kylning samt förbättrar den totala energiåtervinningen. Studien visar att en koldioxidupptagningsgrad på 90% medför en betydande energipåverkan, där nästan hälften av kraftverkets totala effekt konsumeras. Detta minskar den elektriska verkningsgraden från 43% till 21,3%, då energi omdirigeras till CO2-uppfångning och tillhörande processer som luftseparationsenheten (ASU) för syreproduktion i kalkugnen och CO2-komprimering för förvätskning. Det beräknade specifika primära energibehovet för undvikna CO2 (SPECCA) på 3,85 MJ/kg-CO2 för NGCC med NaOH-absorption var något högre än för NGCC med aminabsorption (3,45 MJ/kg-CO2), vilket belyser den högre energipåverkan hos NaOH-baserade processer. Dessutom har värmeintegrationsoptimering med hjälp av pinchanalys betydligt minskat externa uppvärmnings- och kylkrav och förbättrat energiåtervinning inom systemet. Även om alkaliska koldioxidav, As part of the growing initiatives to mitigate CO2 emissions from fossil fuel-based power generation plants, this study investigates the integration of alkali-based carbon capture systems into natural gas fired combined cycle (NGCC) power plants. The primary goals of this project are to improve the environmental sustainability of these power plants by significantly reducing carbon emissions, thereby contributing to global climate change mitigation efforts. This research involves a comprehensive analysis of key operational parameters, including the liquid-to-gas ratio (L/G) of NaOH solution to flue gas in the absorber section, NaOH concentration, absorber pressure, absorbent flow rate and temperatures of both absorbent and flue gas. Sensitivity analyses were conducted by varying key parameters to understand their impact on CO2 capture rate. The evaluation of key performance indicators (KPIs), including CO2 capture rate, lean and rich loading, and the electrical efficiency of the NGCC power plant, was based on the base case scenario. Additionally, pinch analysis was utilized to optimize heat integration within the system, thereby minimizing external heating and cooling requirements and improving overall energy recovery. The study reveals that achieving a 90% CO2 capture rate imposes a significant energy penalty, consuming nearly half of the power plant's total output. This penalty reduces the plant’s electrical efficiency from 43% to 22%, with the energy being diverted not only to the CO2 capture process itself but also to auxiliary processes such as the air separation unit (ASU) for oxygen production in the calciner and CO2 compression for liquefaction. These processes collectively contribute to the substantial decrease in available power for electricity generation. The calculated Specific Primary Energy Consumption for CO2 Avoided (SPECCA) value of 3.85 MJ/kg-CO2 for the NGCC integrated with NaOH absorption was a bit higher than for NGCC integrated with amine abso

Denna studie undersöker integrationen av alkaliska koldioxidavskiljningssystem i naturgaseldade kombikraftverk (NGCC) som en del av insatserna för att minska koldioxidutsläpp från kraftverk baserade på fossila bränslen. Målet är att förbättra den miljömässiga hållbarheten genom att avsevärt minska koldioxidutsläppen och därmed bidra till globala insatser mot klimatförändringar. Forskningen omfattar en grundlig analys av viktiga driftparametrar, inklusive förhållandet mellan vätska och gas (L/G) för NaOH-lösning till rökgas i absorbersektionen, NaOH-koncentration, absorbertryck, flödeshastighet för absorbent och temperaturer för både absorbent och rökgas. Känslighetsanalyser genomfördes genom att variera dessa parametrar för att förstå deras påverkan på CO2-uppfångningsgraden. Utvärdering av nyckelprestandaindikatorer (KPI), inklusive CO2-uppfångningsgrad, lean och rich loading, samt den elektriska effektiviteten hos NGCC-kraftverket, baserades på basfallsscenariet. Dessutom användes pinchanalys för att optimera värmeintegration inom systemet, vilket minskar behovet av extern uppvärmning och kylning samt förbättrar den totala energiåtervinningen. Studien visar att en koldioxidupptagningsgrad på 90% medför en betydande energipåverkan, där nästan hälften av kraftverkets totala effekt konsumeras. Detta minskar den elektriska verkningsgraden från 43% till 21,3%, då energi omdirigeras till CO2-uppfångning och tillhörande processer som luftseparationsenheten (ASU) för syreproduktion i kalkugnen och CO2-komprimering för förvätskning. Det beräknade specifika primära energibehovet för undvikna CO2 (SPECCA) på 3,85 MJ/kg-CO2 för NGCC med NaOH-absorption var något högre än för NGCC med aminabsorption (3,45 MJ/kg-CO2), vilket belyser den högre energipåverkan hos NaOH-baserade processer. Dessutom har värmeintegrationsoptimering med hjälp av pinchanalys betydligt minskat externa uppvärmnings- och kylkrav och förbättrat energiåtervinning inom systemet. Även om alkaliska koldioxidav, As part of the growing initiatives to mitigate CO2 emissions from fossil fuel-based power generation plants, this study investigates the integration of alkali-based carbon capture systems into natural gas fired combined cycle (NGCC) power plants. The primary goals of this project are to improve the environmental sustainability of these power plants by significantly reducing carbon emissions, thereby contributing to global climate change mitigation efforts. This research involves a comprehensive analysis of key operational parameters, including the liquid-to-gas ratio (L/G) of NaOH solution to flue gas in the absorber section, NaOH concentration, absorber pressure, absorbent flow rate and temperatures of both absorbent and flue gas. Sensitivity analyses were conducted by varying key parameters to understand their impact on CO2 capture rate. The evaluation of key performance indicators (KPIs), including CO2 capture rate, lean and rich loading, and the electrical efficiency of the NGCC power plant, was based on the base case scenario. Additionally, pinch analysis was utilized to optimize heat integration within the system, thereby minimizing external heating and cooling requirements and improving overall energy recovery. The study reveals that achieving a 90% CO2 capture rate imposes a significant energy penalty, consuming nearly half of the power plant's total output. This penalty reduces the plant’s electrical efficiency from 43% to 22%, with the energy being diverted not only to the CO2 capture process itself but also to auxiliary processes such as the air separation unit (ASU) for oxygen production in the calciner and CO2 compression for liquefaction. These processes collectively contribute to the substantial decrease in available power for electricity generation. The calculated Specific Primary Energy Consumption for CO2 Avoided (SPECCA) value of 3.85 MJ/kg-CO2 for the NGCC integrated with NaOH absorption was a bit higher than for NGCC integrated with amine abso

Heat pumps are a promising option to decarbonize the industrial sector. However, their performance at a plant-level can be affected by other process changes. In this work, process changes that improve the heat pump's performance have been identified using Process Change Analysis (PCA), where the background pinch point is used as a reference point for appropriate placement. The effects of the process changes on the heat pump's work requirements are studies by introducing exergy to PCA to form the split exergy grand composite curve. This graph shows the work potential of the streams connected to the heat pump and therefore its work targets. The framework is demonstrated in two case studies. In a biodiesel production plant, it allowed to identify technologies that enhance heat pump performance while reducing overall heating requirements. Here, a heat pump transfers 1.9 MW with a COP of 4.2 but incurs a 40 kW penalty for transferring heat above the background process's pinch temperature. Replacing the wet water washer with a membrane separation unit avoided this penalty, while drastically reducing energy requirements from 0.9 MW to 0.3 MW. in a vinyl chloride monomer-purification process, PCA showed how the extraction of heat by the heat pump impacted the formation of the background pinch, from which an implementation strategy was derived that increased the heat pump's plant-level performance by 6.5% with respect to standard implementation., Energie and Industrie, ChemE/Chemical Engineering

The water-, and energy footprints of the processes in the pulp and paper industry are sizable enough to warrant investment of money and commitment of time truncate the same. Besides, there is also a nexus between water and energy here, with optimisation of the use of one of these resoruces enabling that of the other too. This streamlined review focuses on journal publications (originating from different parts of the world, and targeted at researchers and decision-makers in the industry) which train the lens on the optimisation of water use in this particular sector of the (forestry) bioeconomy. The synergies and complementarities which exist among different sustainable development goals (SDGs) , promise positive ripple effects, caused by attending to the truncation of the water footprint. The articles, in general, recommend effective in-plant wastewater treatment in combinaton with recirculating the treated effluent, and looking upon the water streams as carriers or bearers of valorisable substances – organics which can yield a host of bio-products in bio-refineries, including bio-energy. Availing of water-pinch analysis as a tool to uncover possibilities of water use in a cascade (depending upon the requirements imposed on the water, by processes downstream in the cascade), has been shown to aid in the optimisation of both water use and energy demand within the plant. One case study, for example, showed that the demand for steam can be decreased by about 4 GJ per ton of output, by recovering the waste heat in the water streams., Omvandling av två rapporter skrevet av fyra studenter i kursen Forskning och Utvecklingsprojekt......till en artikkel på engelska.....Den femte författaren G Venkatesh var handledaren och översättare.

The water-, and energy footprints of the processes in the pulp and paper industry are sizable enough to warrant investment of money and commitment of time truncate the same. Besides, there is also a nexus between water and energy here, with optimisation of the use of one of these resoruces enabling that of the other too. This streamlined review focuses on journal publications (originating from different parts of the world, and targeted at researchers and decision-makers in the industry) which train the lens on the optimisation of water use in this particular sector of the (forestry) bioeconomy. The synergies and complementarities which exist among different sustainable development goals (SDGs) , promise positive ripple effects, caused by attending to the truncation of the water footprint. The articles, in general, recommend effective in-plant wastewater treatment in combinaton with recirculating the treated effluent, and looking upon the water streams as carriers or bearers of valorisable substances – organics which can yield a host of bio-products in bio-refineries, including bio-energy. Availing of water-pinch analysis as a tool to uncover possibilities of water use in a cascade (depending upon the requirements imposed on the water, by processes downstream in the cascade), has been shown to aid in the optimisation of both water use and energy demand within the plant. One case study, for example, showed that the demand for steam can be decreased by about 4 GJ per ton of output, by recovering the waste heat in the water streams., Omvandling av två rapporter skrevet av fyra studenter i kursen Forskning och Utvecklingsprojekt......till en artikkel på engelska.....Den femte författaren G Venkatesh var handledaren och översättare.

The water-, and energy footprints of the processes in the pulp and paper industry are sizable enough to warrant investment of money and commitment of time truncate the same. Besides, there is also a nexus between water and energy here, with optimisation of the use of one of these resoruces enabling that of the other too. This streamlined review focuses on journal publications (originating from different parts of the world, and targeted at researchers and decision-makers in the industry) which train the lens on the optimisation of water use in this particular sector of the (forestry) bioeconomy. The synergies and complementarities which exist among different sustainable development goals (SDGs) , promise positive ripple effects, caused by attending to the truncation of the water footprint. The articles, in general, recommend effective in-plant wastewater treatment in combinaton with recirculating the treated effluent, and looking upon the water streams as carriers or bearers of valorisable substances – organics which can yield a host of bio-products in bio-refineries, including bio-energy. Availing of water-pinch analysis as a tool to uncover possibilities of water use in a cascade (depending upon the requirements imposed on the water, by processes downstream in the cascade), has been shown to aid in the optimisation of both water use and energy demand within the plant. One case study, for example, showed that the demand for steam can be decreased by about 4 GJ per ton of output, by recovering the waste heat in the water streams., Omvandling av två rapporter skrevet av fyra studenter i kursen Forskning och Utvecklingsprojekt......till en artikkel på engelska.....Den femte författaren G Venkatesh var handledaren och översättare.

Heat recovery plays a pivotal role in enhancing energy efficiency and reducing operating costs in the energy sector. In the context of greenhouse energy management, heat recovery measures hold significant potential to improve overall efficiency and profitability while improving sustainability. By specifically targeting ventilation waste heat, it is aimed to identify efficient and innovative ways to harness this abundant but often overlooked energy source. The primary objective of this thesis is to present a systematic methodology that offers practical insights into the design of a heat recovery system for greenhouses using heat integration technique. Considering the dynamic nature of greenhouse processes, dynamic Pinch Analysis (PA) is applied for the very first time to design an integrated greenhouse heating, cooling, and ventilation system. So, in the first step, the greenhouse climate conditioning system is defined in terms of distinct streams representing different components and processes within the system. This stream-based representation allows for a comprehensive understanding of the system's thermal dynamics, facilitating heat recovery analysis. Then, the required data to fully define all streams as a function of time (i.e. thermal and ventilation requirements) are calculated using a greenhouse climate model developed in Matlab/Simulink. Dynamic PA is accomplished in two major steps: energy targeting and heat exchanger network design. By employing energy targeting techniques based on graphical PA (composite curves), the methodology identifies heat recovery opportunities and determines the integration possibilities within the greenhouse. In the next step, a heuristic approach is presented to allocate a suitable heat exchanger network to the streams, thereby achieving the set energy targets. In this approach, the HEN design problem is solved only for the most representative time periods (i.e. typical days) determined using clustering. This can cons, La récupération de chaleur joue un rôle crucial dans l'amélioration de l'efficacité énergétique et la réduction des coûts opérationnels dans le secteur de l'énergie. Dans le contexte de la gestion de l'énergie des serres, les mesures de récupération de chaleur offrent un potentiel significatif pour améliorer l'efficacité globale et la rentabilité tout en favorisant la durabilité. En ciblant spécifiquement la chaleur perdue par la ventilation, notre objectif est d'identifier des moyens efficaces et innovants pour exploiter cette source d'énergie abondante mais souvent négligée. Cette thèse a pour principal objectif de présenter une méthodologie systématique offrant des aperçus pratiques sur la conception d'un système de récupération de chaleur pour les serres en utilisant la technique d'intégration thermique. Compte tenu de la nature dynamique des processus des serres, l'Analyse Pinch dynamique (PA) est appliquée pour la toute première fois afin de concevoir un système de chauffage, de refroidissement et de ventilation intégré pour les serres. Ainsi, dans un premier temps, le système de conditionnement du climat des serres est défini en termes de flux distincts représentant les différents composants et processus au sein du système. Cette représentation basée sur les flux permet de comprendre de manière exhaustive la dynamique thermique du système, facilitant ainsi l'analyse de récupération de chaleur. Ensuite, les données requises pour définir entièrement tous les flux en fonction du temps (c'est-à-dire les besoins thermiques et de ventilation) sont calculées à l'aide d'un modèle climatique de serre développé dans Matlab/Simulink. L'Analyse Pinch dynamique est réalisée en deux étapes majeures: le ciblage énergétique et la conception du réseau d'échangeurs de chaleur. En utilisant des techniques de ciblage énergétique basées sur l'Analyse Pinch graphique (courbes composites), la méthodologie identifie les opportunités de récupération de chaleur et détermine les possib

Sustainable energy solutions are highly dependent on the availability and costs of resources during their operation. For instance, power output of solar cells and wind turbines vary over time which impacts the technical, economic, and environmental feasibility of Power-to-X (P2X) systems. In addition, efficient system solutions for energy conversion will require an optimal heat integration between several technologies and conversion routes. Thus, several methods have been proposed to conceptualize and optimize the design and operation of process plants. However, the possibilities of heat integration and storage during dynamic operation of different P2X-processes have been rarely evaluated by existing methods in literature. In this context, this research aims to provide an optimization framework, based on linear optimization and pinch analysis, to fill this knowledge gap, crucial to the development of dynamic renewable systems. The novel method is exemplified in the optimization of a Power-to-Methanol plant using solid oxide cells (SOCs) subjected to varying electricity production of wind turbines. The optimization estimates a minimal methanol production cost of 1772-1793 USD/ton for integrated scenarios and 1820-1807 USD/ton for non-integrated cases. Thus, heat integration plays a crucial role in cutting up to 2% of fuel production cost, while storage and optimal operation reduces further 3.3 % of the electrolysis size compared with reference scenarios.

To mitigate climate change, a stronger reliance on renewable energy sources is foreseen, and Power-to-Hydrogen systems can be adopted to minimize curtailment losses derived from the intermittent nature of wind and solar power. Among different alternatives, alkaline water electrolysis is the most mature process for hydrogen production using sustainable electricity as its main energy source. The mathematical modelling of the alkaline electrolysis process is a crucial tool to improve green hydrogen production, energy conversion efficiency, sizing (model-based design) and thermal energy management. Although several studies have investigated alkaline electrolysis modelling, these analyses often neglect property variations along the stack area and its economic implications. In this work, the need for increasing the modelling complexity in system models by introducing a one-dimensional model of the alkaline electrolyzer cell/stack is investigated. With this, several operation parameter variations can be modelled, and among these, the internal temperature variation plays a crucial role in both technical and economic aspects. Results show that efficiency could vary between 58-70% while the Levelized cost of hydrogen is within the range of 1.3-1.6 €/kg, when various inlet-outlet temperature differences are considered. Furthermore, from both technical and economic aspects, the optimal temperature control of alkaline electrolysis is to maintain a very low-temperature difference (~1°C), from inlet to outlet, controllable with the alteration of the electrolyte flow rate.

Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

Le secteur du bâtiment consomme une grande partie de l'énergie produite dans un pays et, par conséquent, il est responsable d'une grande quantité correspondante d'émissions de gaz à effet de serre dans l'atmosphère et du problème du réchauffement climatique. Au cours des dernières décennies, des efforts ont été déployés pour remplacer en partie l'énergie nécessaire au les charges de chauffage/refroidissement/eau chaude sanitaire dans les bâtiments par des sources d'énergie renouvelables, des sources de déchets disponibles et des pompes à chaleur. Cependant, une approche systématique capable de satisfaire toutes les charges mentionnées et d'assurer la récupération de chaleur interne maximale fait toujours défaut. De plus, il n'y a pas d'approche systématique pour le dimensionnement des équipements tels que la surface des panneaux solaires, la capacité d'une pompe à chaleur, la charge et la taille/configuration des échangeurs de chaleur au sol (GHE), etc. pour les bâtiments. L'analyse par pincement est une technique d'intégration de chaleur bien connue qui a été utilisée pour la récupération de chaleur dans de grandes installations industrielles, principalement pour des processus en régime permanent. De plus, cette approche a été adoptée pour couvrir les processus batch, lorsque les flux chaud/froid avec des charges constantes représentent un comportement marche/arrêt pendant le temps batch. Néanmoins, les charges (c'est-à-dire les flux chauds/froids, y compris les sources renouvelables et les déchets) dans un bâtiment sont très dynamiques et dépendent du temps et les modèles de moyenne temporelle ou de tranches de temps actuellement disponibles ne peuvent pas gérer le dynamisme de charge mentionné. De plus, l'inadéquation temporelle entre les sources disponibles et les demandes nécessite l'intégration d'un ou plusieurs stockages d'énergie (par exemple, stockage d'énergie thermique/électrique). L'objectif de cette thèse est de développer un modèle basé sur le pincemen, Building sector consumes a large portion of produced energy in a country and, consequently, it is responsible for a corresponding large amount of greenhouse gas emissions into the atmosphere and the global warming issue. There have been efforts to partly replace the required energy for heating/cooling/domestic hot water loads in buildings by renewable sources of energy, available waste sources, and heat pumping in recent decades. However, a systematic approach that can satisfy all the mentioned loads and ensure the maximum internal heat recovery is still missing. Additionally, there is no systematic approach for sizing the equipment such as area of solar panels, the capacity of a heat pump, the load and size/configuration of ground heat exchangers (GHEs), etc. for buildings. Pinch analysis is a well-known heat integration technique which has been utilized for heat recovery in large industrial plants, mostly for steady state processes. Furthermore, this approach has been adopted to cover the batch processes, when hot/cold streams with constant loads represent an on/off behavior during the batch time. Nonetheless, the loads (i.e., hot/cold streams, including renewable and waste sources) in a building are highly dynamic and time dependent and the current available time average or time-slice models cannot handle the mentioned load dynamism. Furthermore, the time mismatch among the available sources and the demands requires integration of one or several energy storages (e.g., thermal/electrical energy storage). The objective of this thesis is to develop a thermal pinch-based model to systematically include the intermittent nature of renewable and waste energy sources in buildings. Therefore, in this thesis, a systematic pinch approach is developed that can include all building’s dynamic loads in the heat recovery and convert the problem of equipment sizing into the matching between hot/cold streams. In this context and in the beginning, the available time slic

Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

A thermodynamically oriented method is developed to identify the theoretical and practical limits of pressure-retarded osmosis (PRO) on converting salinity gradient power to mechanical energy under constant operating pressure with infinite and finite mass exchange area, respectively. It is proved that pinch analysis can be used to find the mass exchange limit of PRO, and according to which draw and feed streams can be plotted on a graph of net osmotic pressure - water exchange. Based on the graphical method, an expression of optimal pressure change is derived that achieves the maximum work extraction of a PRO process with single draw/feed stream. Moreover, problem table method is presented that serves as an analytical procedure to determine the maximum extractable work of the conceptualized multi-stream PRO process. Examples of both a PRO process with a draw stream (0.6 M NaCl seawater) and a feed stream feed (0.015 M NaCl river water) and a multi-stream PRO are included to illustrate the proposed methods. Results of the former example show that the counter-current design achieves 30.85% and 31.49% increase, respectively, in the maximum theoretical and practical work output, compared with the co-current design. The latter example shows that the problem table method produces a 20.47% increase in the work output, compared with the standalone design. © 2022 Elsevier Ltd

Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

Production of formalin, which is among the highest production volume chemicals, is highly energy-intensive; thus, reduction of energy use is very important in reducing cost and emissions. The aim of this and its larger overall research is to systemically analyze how to improve sustainability of processes producing formalin as an intermediate or final product. In this part of the work, energy consumption requirements are analyzed for the conventional formalin production process via methane steam reforming, where opportunities for energy consumption reduction are identified. This work will serve as a base case for further investigation of alternative formalin production pathways. To achieve energy savings, heat integration technology by combined pinch analysis and mathematical programming is applied. The formalin production process is simulated using Aspen HYSYS, and heat integration of the production process was performed based on simulated design using GAMS software. Economic and environmental footprint analyses were performed for both non-integrated and integrated designs. Results show that heat integration reduces heat consumption by around 39%, leading to a saving of 11% in capital cost and turning annual operating cost into positive revenue. Heat integration also improves the environmental aspect, where a 7-22% reduction in selected environmental footprints is achieved., ChemE/Delft Ingenious Design

The number of large-scale heat pumps (HP) implemented in Danish district heating networks has increased in recent years. The installations are often custom-made solutions designed carefully to obtain a high Coefficient of Performance (COP). This study aims at quantifying and compare five approaches for improving the COP of a heat pump, with a one-stage ammonia cycle used as the reference case with sink temperatures of 50 °C/80 °C (in/out) and source temperatures of 10 °C/3 °C. The approaches include increased complexity of cycle layout, optimization of intermediate pressure in two-stage cycles, a connection of HP cycles in series, optimization of load share between heating capacity for HPs in series, and optimal design of heat exchanger networks (HEN). The latter is based on an implementation of pinch analysis to HP HENs. The results revealed an improvement in COP by +15.8% obtained with increased complexity of cycle layout (two-stage cycle with a low-stage desuperheater) compared to a COP of 2.98 for the reference case. Connecting up to three one-stage HPs and two-stage cycles in series improved COP by 4.42% and 24.5%, respectively. The benefit of optimal load share and intermediate pressure was less than 0.5 % points for all configurations compared to reference values based on theoretical approaches. Exploiting the potential for optimal HEN increased the potential to 10.4% for one-stage cycles in series and nearly 29% for two-stage cycles increasing the COP to a maximum of 3.84.

Production of formalin, which is among the highest production volume chemicals, is highly energy-intensive; thus, reduction of energy use is very important in reducing cost and emissions. The aim of this and its larger overall research is to systemically analyze how to improve sustainability of processes producing formalin as an intermediate or final product. In this part of the work, energy consumption requirements are analyzed for the conventional formalin production process via methane steam reforming, where opportunities for energy consumption reduction are identified. This work will serve as a base case for further investigation of alternative formalin production pathways. To achieve energy savings, heat integration technology by combined pinch analysis and mathematical programming is applied. The formalin production process is simulated using Aspen HYSYS, and heat integration of the production process was performed based on simulated design using GAMS software. Economic and environmental footprint analyses were performed for both non-integrated and integrated designs. Results show that heat integration reduces heat consumption by around 39%, leading to a saving of 11% in capital cost and turning annual operating cost into positive revenue. Heat integration also improves the environmental aspect, where a 7-22% reduction in selected environmental footprints is achieved., ChemE/Delft Ingenious Design

The “bridge framework” is a systematic decision-making support tool for process integration retrofit of industrial plants, which proposes the use of “bridge analysis” in a structured fashion. Its potential of rigorously analysing industrial processes has been discussed, but no applications on actually operating plants considering process constraints have been presented to date. The paper demonstrates the capabilities of the bridge framework in analysing an actually operating milk powder production plant. Its step-by-step application is thoroughly described and discussed, highlighting inherent strengths and weaknesses of the method. Moreover, a clarification of the “energy transfer diagram” is proposed, distinguishing avoidable and unavoidable heat degradation in the heat exchanger network by introducing the concept of “limit heat transfer interface”. The results proved that the bridge framework is a rigorous tool, which provided valuable insight to the analyst aiding the open-ended decision-making activities related to the retrofit of both process operations and heat exchanger network. Seven design proposals were identified, out of which the best resulted in 54000 €/y of economic saving with an internal rate of return of 34% and a minimum risk level. The step-by-step application of the method demonstrated that good engineering judgement is critical for achieving beneficial solutions. Expertise on process operations as well as energy analytics is essential for completing the project. Finally, the concept of “limit heat transfer interface” allowed to completely link bridge analysis and pinch analysis and to clarify the meaning of the “grand composite curve”.

This study provides suggestions to decrease hot utility use and impact on the environment of a skim milk powder (SMP) processing plant. These suggestions are based on the integration of waste streams with processes in the production of SMP. To identify appropriate waste and process streams, process integration has proven to be a successful method. This concept addresses the issue of waste heat of a process by pointing out to the importance of the relation between unit-processes. In this study, the integration of waste streams is accomplished by heat exchangers, heat pumps and a zeolite wheel. The general assumption underlying this research, is that recovering heat from unused waste streams decreases hot utility use. Multiple methodologies were used in this study. To accomplish process integration, the pinch analysis forms an essential tool. This analysis was used to identify potential heat recovery schemes in the SMP plant. Furthermore, to fully understand these schemes, a thermal, environmental and economical analysis was done. These analyses were based on mass and energy balances, (in)direct CO2 emissions and investment and operational costs. Several conclusion can be drawn from the pinch analysis. First, the pinch temperature is 50◦C. This represents the dividing line between processes which require heating and cooling. Second, the heating and cooling demand is known. The SMP production process requires 6.8 MW of external heating and 1.7 MW of external cooling. Third, the amount of recoverable heat is equal to 5.3 MW. Fourth, appropriate heat sink and sources are identified. The heat sources, i.e. waste streams, are the spray dryer exhaust and the the condensate streams from two evaporators. The supply temperatures of the exhaust and the condensate streams are respectively 77, 65 and 55◦C. The appropriate heat sinks are the spray dryer air inlet and the evaporator product inlet streams. The target temperature of the spray dryer inlet and evaporator inlet streams a, Industrial Ecology

[ES] Esta tesis investiga la integración de grandes bombas de calor para el enfriamiento de un centro de datos, aprovechando el calor excedido con la Red de Calefacción urbana, aumentando su temperatura de 45ºC a 85ºC. Concretamente, está previsto ayudar al gobierno Danés con los objetivos de reducción de emisiones establecidos para 2050. El proyecto se centra especialmente en un centro de datos específico ubicado en Kassø, que tiene una necesidad de enfriamiento de aproximadamente 27MW. Para esta instalación se estudia la mejor opción en términos de fuente de calor, aire o agua, y para otros componentes como el tipo de compresor. El resultado reveló que el agua como fuente es preferible, y por tanto se evalúa dicha fuente de calor para la operación con bombas de calor de una etapa y de dos etapas, buscando configuraciones nuevas que pueden aumentar el rendimiento del sistema. El método 'pinch' se aplica a las mejores opciones resultantes, y una diferencia de temperatura óptima se encontrará para obtener la mejor eficiencia alcanzable, y una mejora del 2.84% y 3.76% en el COP se muestra como resultado de la optimización 'pinch' para las bombas de calor de una y dos etapas, respectivamente. Para estos casos, es necesario diseñar una red de Intercambiadores de calor capaz de cumplir los requisitos de la optimización. Por lo tanto, dos redes se diseñan para las mejores configuraciones, en el caso del sitema con una etapa, no es posible lograr la diferencia de temperatura, establecida en 3K, y para el sistema de dos etapas, 2.93K se alcanza con 18 intercambiadores, considerando la red válida para su implementación., [EN] This thesis investigates the integration of large Heat Pumps for the Datacenter cooling, taking profit from the exceeded heat with the District Heating Network, increasing its temperature from 45ºC to 85ºC. Concretely, is planned to help the Danish Government with the emission reduction objectives set by 2050. The project is particularly focus on a specific datacenter placed in Kassø, which has a cooling necessity of approximately 27MW. For this facility is studied the best option in terms of heat source, Air or Water, and for other components such the compressor type. The result revealed that water as source is preferable, and this option is evaluated for the operation with one-stage and two-stage Heat pumps, looking for some new configurations that can increase the performance of the system. The pinch method is applied to the resulting best options, and an optimal pinch point will be found to obtain the best efficiency reachable, and an improvement of the 2.84% and 3.76% in the COP is showed as a result of the pinch optimization for the one and two-stage Heat pumps, respectively. For these cases, is necessary to design a Heat Exchanger Network able to fulfil the requirements of the optimization. Therefore, two HEN are designed for the best ammonia configurations, for the case of the onestage, is not possible to achieve the temperature difference, set as 3K, and for the twostage 2.93K is reached with 18 exchangers, considering the HEN valid for its implementation.

[ES] Esta tesis investiga la integración de grandes bombas de calor para el enfriamiento de un centro de datos, aprovechando el calor excedido con la Red de Calefacción urbana, aumentando su temperatura de 45ºC a 85ºC. Concretamente, está previsto ayudar al gobierno Danés con los objetivos de reducción de emisiones establecidos para 2050. El proyecto se centra especialmente en un centro de datos específico ubicado en Kassø, que tiene una necesidad de enfriamiento de aproximadamente 27MW. Para esta instalación se estudia la mejor opción en términos de fuente de calor, aire o agua, y para otros componentes como el tipo de compresor. El resultado reveló que el agua como fuente es preferible, y por tanto se evalúa dicha fuente de calor para la operación con bombas de calor de una etapa y de dos etapas, buscando configuraciones nuevas que pueden aumentar el rendimiento del sistema. El método 'pinch' se aplica a las mejores opciones resultantes, y una diferencia de temperatura óptima se encontrará para obtener la mejor eficiencia alcanzable, y una mejora del 2.84% y 3.76% en el COP se muestra como resultado de la optimización 'pinch' para las bombas de calor de una y dos etapas, respectivamente. Para estos casos, es necesario diseñar una red de Intercambiadores de calor capaz de cumplir los requisitos de la optimización. Por lo tanto, dos redes se diseñan para las mejores configuraciones, en el caso del sitema con una etapa, no es posible lograr la diferencia de temperatura, establecida en 3K, y para el sistema de dos etapas, 2.93K se alcanza con 18 intercambiadores, considerando la red válida para su implementación., [EN] This thesis investigates the integration of large Heat Pumps for the Datacenter cooling, taking profit from the exceeded heat with the District Heating Network, increasing its temperature from 45ºC to 85ºC. Concretely, is planned to help the Danish Government with the emission reduction objectives set by 2050. The project is particularly focus on a specific datacenter placed in Kassø, which has a cooling necessity of approximately 27MW. For this facility is studied the best option in terms of heat source, Air or Water, and for other components such the compressor type. The result revealed that water as source is preferable, and this option is evaluated for the operation with one-stage and two-stage Heat pumps, looking for some new configurations that can increase the performance of the system. The pinch method is applied to the resulting best options, and an optimal pinch point will be found to obtain the best efficiency reachable, and an improvement of the 2.84% and 3.76% in the COP is showed as a result of the pinch optimization for the one and two-stage Heat pumps, respectively. For these cases, is necessary to design a Heat Exchanger Network able to fulfil the requirements of the optimization. Therefore, two HEN are designed for the best ammonia configurations, for the case of the onestage, is not possible to achieve the temperature difference, set as 3K, and for the twostage 2.93K is reached with 18 exchangers, considering the HEN valid for its implementation.

[ES] Esta tesis investiga la integración de grandes bombas de calor para el enfriamiento de un centro de datos, aprovechando el calor excedido con la Red de Calefacción urbana, aumentando su temperatura de 45ºC a 85ºC. Concretamente, está previsto ayudar al gobierno Danés con los objetivos de reducción de emisiones establecidos para 2050. El proyecto se centra especialmente en un centro de datos específico ubicado en Kassø, que tiene una necesidad de enfriamiento de aproximadamente 27MW. Para esta instalación se estudia la mejor opción en términos de fuente de calor, aire o agua, y para otros componentes como el tipo de compresor. El resultado reveló que el agua como fuente es preferible, y por tanto se evalúa dicha fuente de calor para la operación con bombas de calor de una etapa y de dos etapas, buscando configuraciones nuevas que pueden aumentar el rendimiento del sistema. El método 'pinch' se aplica a las mejores opciones resultantes, y una diferencia de temperatura óptima se encontrará para obtener la mejor eficiencia alcanzable, y una mejora del 2.84% y 3.76% en el COP se muestra como resultado de la optimización 'pinch' para las bombas de calor de una y dos etapas, respectivamente. Para estos casos, es necesario diseñar una red de Intercambiadores de calor capaz de cumplir los requisitos de la optimización. Por lo tanto, dos redes se diseñan para las mejores configuraciones, en el caso del sitema con una etapa, no es posible lograr la diferencia de temperatura, establecida en 3K, y para el sistema de dos etapas, 2.93K se alcanza con 18 intercambiadores, considerando la red válida para su implementación., [EN] This thesis investigates the integration of large Heat Pumps for the Datacenter cooling, taking profit from the exceeded heat with the District Heating Network, increasing its temperature from 45ºC to 85ºC. Concretely, is planned to help the Danish Government with the emission reduction objectives set by 2050. The project is particularly focus on a specific datacenter placed in Kassø, which has a cooling necessity of approximately 27MW. For this facility is studied the best option in terms of heat source, Air or Water, and for other components such the compressor type. The result revealed that water as source is preferable, and this option is evaluated for the operation with one-stage and two-stage Heat pumps, looking for some new configurations that can increase the performance of the system. The pinch method is applied to the resulting best options, and an optimal pinch point will be found to obtain the best efficiency reachable, and an improvement of the 2.84% and 3.76% in the COP is showed as a result of the pinch optimization for the one and two-stage Heat pumps, respectively. For these cases, is necessary to design a Heat Exchanger Network able to fulfil the requirements of the optimization. Therefore, two HEN are designed for the best ammonia configurations, for the case of the onestage, is not possible to achieve the temperature difference, set as 3K, and for the twostage 2.93K is reached with 18 exchangers, considering the HEN valid for its implementation.

[ES] Esta tesis investiga la integración de grandes bombas de calor para el enfriamiento de un centro de datos, aprovechando el calor excedido con la Red de Calefacción urbana, aumentando su temperatura de 45ºC a 85ºC. Concretamente, está previsto ayudar al gobierno Danés con los objetivos de reducción de emisiones establecidos para 2050. El proyecto se centra especialmente en un centro de datos específico ubicado en Kassø, que tiene una necesidad de enfriamiento de aproximadamente 27MW. Para esta instalación se estudia la mejor opción en términos de fuente de calor, aire o agua, y para otros componentes como el tipo de compresor. El resultado reveló que el agua como fuente es preferible, y por tanto se evalúa dicha fuente de calor para la operación con bombas de calor de una etapa y de dos etapas, buscando configuraciones nuevas que pueden aumentar el rendimiento del sistema. El método 'pinch' se aplica a las mejores opciones resultantes, y una diferencia de temperatura óptima se encontrará para obtener la mejor eficiencia alcanzable, y una mejora del 2.84% y 3.76% en el COP se muestra como resultado de la optimización 'pinch' para las bombas de calor de una y dos etapas, respectivamente. Para estos casos, es necesario diseñar una red de Intercambiadores de calor capaz de cumplir los requisitos de la optimización. Por lo tanto, dos redes se diseñan para las mejores configuraciones, en el caso del sitema con una etapa, no es posible lograr la diferencia de temperatura, establecida en 3K, y para el sistema de dos etapas, 2.93K se alcanza con 18 intercambiadores, considerando la red válida para su implementación., [EN] This thesis investigates the integration of large Heat Pumps for the Datacenter cooling, taking profit from the exceeded heat with the District Heating Network, increasing its temperature from 45ºC to 85ºC. Concretely, is planned to help the Danish Government with the emission reduction objectives set by 2050. The project is particularly focus on a specific datacenter placed in Kassø, which has a cooling necessity of approximately 27MW. For this facility is studied the best option in terms of heat source, Air or Water, and for other components such the compressor type. The result revealed that water as source is preferable, and this option is evaluated for the operation with one-stage and two-stage Heat pumps, looking for some new configurations that can increase the performance of the system. The pinch method is applied to the resulting best options, and an optimal pinch point will be found to obtain the best efficiency reachable, and an improvement of the 2.84% and 3.76% in the COP is showed as a result of the pinch optimization for the one and two-stage Heat pumps, respectively. For these cases, is necessary to design a Heat Exchanger Network able to fulfil the requirements of the optimization. Therefore, two HEN are designed for the best ammonia configurations, for the case of the onestage, is not possible to achieve the temperature difference, set as 3K, and for the twostage 2.93K is reached with 18 exchangers, considering the HEN valid for its implementation.

Aiming for more energetically efficient and sustainable solutions, academic attention to work and heat integration (WHI) has grown in the last decade. Simultaneous models for work and heat exchanger network (WHEN) synthesis often derive from heat integration (HI) frameworks. However, it can be noted that simultaneous optimization models for WHI are considerably more complex to solve than in the HI case. The design of efficient pressure manipulation routes (i.e., allocation and sizing of compression and expansion machinery) in process streams prior to heat exchange match allocation can make the optimization procedure more efficient. This work proposes a systematic procedure based on a model that employs Pinch Analysis concepts for defining these routes based on capital and operating cost targets. The solution approach is a hybrid meta-heuristic method based on Simulated Annealing (SA) and Particle Swarm Optimization (PSO). The obtained routes are then converted into a HI problem by fixing pressure manipulation unit sizes. The detailed HI solution is finally transferred into a WHI optimization model as initial design. In the two tackled examples, the total annual costs (TAC) predicted by the Pinch-based model differed by 0.5% and 1.2% from the final optimized WHEN obtained in the detailed WHI framework.

Dans un contexte mondial marqué par la lutte contre les changements climatiques et la dépendance des ressources d’énergies fossiles, la carbonatation minérale constitue une solution d’accompagnement dans l’attente de la transition énergétique. Il s’agit d’une réaction spontanée et exothermique entre le CO₂ et des oxydes métalliques, comme les oxydes de calcium et de magnésium présents dans certains déchets industriels ou résidus miniers, qui permet de stocker le CO₂ sous forme de carbonates à l’état solide thermodynamiquement stable. Cette étude est la suite des précédents travaux réalisés au sein de l’équipe de recherche à l’Institut national de la recherche scientifique qui ont mené au développement du procédé INRS. Ce procédé exploite les résidus miniers de serpentine riches en oxydes de magnésium résultants de l’ancienne activité minière dans le sud de la province du Québec. Dans ce procédé, la carbonatation est réalisée en trois étapes : l’activation thermique de la serpentine sous haute température, la dissolution de cette dernière après sa mise en contact avec le gaz contenant le CO₂ en solution sous température ambiante et une pression de 11.5 bars, suivie d’une réaction de précipitation pour former les carbonates sous une température plus élevée (>40°C). Dans cette thèse, la faisabilité de la réaction de dissolution sous pression atmosphérique a été démontrée. Le taux d’avancement de la réaction de dissolution de la serpentine a atteint 32% avec une concentration massique de serpentine en solution de 10%, soit pratiquement le même taux obtenu avec le même matériel sous une pression de 11,5 bars avec une concentration massique de 15%. Par la suite, une intégration énergétique avec une analyse par pincement a été réalisée dans le but d’optimiser l’exploitation des différentes sources de chaleur perdues dans le procédé. Cela a permis de réduire la demande en énergie thermique de 16%. Cela a aussi eu pour conséquence d’améliorer l’efficacité de séquestration ne

Aiming for more energetically efficient and sustainable solutions, academic attention to work and heat integration (WHI) has grown in the last decade. Simultaneous models for work and heat exchanger network (WHEN) synthesis often derive from heat integration (HI) frameworks. However, it can be noted that simultaneous optimization models for WHI are considerably more complex to solve than in the HI case. The design of efficient pressure manipulation routes (i.e., allocation and sizing of compression and expansion machinery) in process streams prior to heat exchange match allocation can make the optimization procedure more efficient. This work proposes a systematic procedure based on a model that employs Pinch Analysis concepts for defining these routes based on capital and operating cost targets. The solution approach is a hybrid meta-heuristic method based on Simulated Annealing (SA) and Particle Swarm Optimization (PSO). The obtained routes are then converted into a HI problem by fixing pressure manipulation unit sizes. The detailed HI solution is finally transferred into a WHI optimization model as initial design. In the two tackled examples, the total annual costs (TAC) predicted by the Pinch-based model differed by 0.5% and 1.2% from the final optimized WHEN obtained in the detailed WHI framework.

Process heat integration in batch processes is a complex problem given their time dependent behavior and need for thermal energy storage. In case of multi-product batch processes the complexity increases further. Due to its intricacy, the topic has so far been hardly addressed in literature. This article presents a practical case study on heat integration of such complex batch processes in a medium-sized European textile plant using pinch analysis. The maximum heat recovery potential during different time slices of a day is estimated at 21–43% of the heat demand of the company. The processes are first optimized for direct heat recovery and a heat exchanger network is recommended with a maximum recovery potential of 85 GJ per day. The residual process requirements are then analyzed for indirect heat recovery by means of thermal energy storage. A closed intermediate loop and heat storage system with four temperature levels is recommended with an additional recovery potential of 17 GJ per day. The proposed heat exchanger and storage designs are both found to be cost‐effective with payback times ranging from 1 to 5 years. In spite of being technically rather demanding, more attention should be paid to thermal energy storage in batch processes since they are likely to offer more attractive additional energy saving potentials in industry. The approach provides an effective way of identifying practical solutions for heat integration in complex multi-product batch processes., + ID der Publikation: hslu_75371 + Art des Beitrages: Wissenschaftliche Medien + Sprache: Englisch + Letzte Aktualisierung: 2022-11-03 09:12:38

Process heat integration in batch processes is a complex problem given their time dependent behavior and need for thermal energy storage. In case of multi-product batch processes the complexity increases further. Due to its intricacy, the topic has so far been hardly addressed in literature. This article presents a practical case study on heat integration of such complex batch processes in a medium-sized European textile plant using pinch analysis. The maximum heat recovery potential during different time slices of a day is estimated at 21–43% of the heat demand of the company. The processes are first optimized for direct heat recovery and a heat exchanger network is recommended with a maximum recovery potential of 85 GJ per day. The residual process requirements are then analyzed for indirect heat recovery by means of thermal energy storage. A closed intermediate loop and heat storage system with four temperature levels is recommended with an additional recovery potential of 17 GJ per day. The proposed heat exchanger and storage designs are both found to be cost‐effective with payback times ranging from 1 to 5 years. In spite of being technically rather demanding, more attention should be paid to thermal energy storage in batch processes since they are likely to offer more attractive additional energy saving potentials in industry. The approach provides an effective way of identifying practical solutions for heat integration in complex multi-product batch processes., + ID der Publikation: hslu_75371 + Art des Beitrages: Wissenschaftliche Medien + Sprache: Englisch + Letzte Aktualisierung: 2022-11-03 09:12:38

Process heat integration in batch processes is a complex problem given their time dependent behavior and need for thermal energy storage. In case of multi-product batch processes the complexity increases further. Due to its intricacy, the topic has so far been hardly addressed in literature. This article presents a practical case study on heat integration of such complex batch processes in a medium-sized European textile plant using pinch analysis. The maximum heat recovery potential during different time slices of a day is estimated at 21–43% of the heat demand of the company. The processes are first optimized for direct heat recovery and a heat exchanger network is recommended with a maximum recovery potential of 85 GJ per day. The residual process requirements are then analyzed for indirect heat recovery by means of thermal energy storage. A closed intermediate loop and heat storage system with four temperature levels is recommended with an additional recovery potential of 17 GJ per day. The proposed heat exchanger and storage designs are both found to be cost‐effective with payback times ranging from 1 to 5 years. In spite of being technically rather demanding, more attention should be paid to thermal energy storage in batch processes since they are likely to offer more attractive additional energy saving potentials in industry. The approach provides an effective way of identifying practical solutions for heat integration in complex multi-product batch processes., + ID der Publikation: hslu_75371 + Art des Beitrages: Wissenschaftliche Medien + Sprache: Englisch + Letzte Aktualisierung: 2022-11-03 09:12:38

Energy efficiency in oil refineries is an effective measure to reduce greenhouse gas emissions and energy use. Research has focused on the application of heat integration in industries; however, little emphasis is given to the practical use of unreliable/unavailable data from the industries and its integration with the energy system. The study used temperature correction factors to produce a balanced heat exchanger network and study the use of excess heat for district heating. It also validated the proposed retrofits by analysing the impact of the retrofit on the area of all heat exchangers in the network. Finally, it evaluates the robustness of the results due to input temperatures and mass flow rates. A Pinch analysis of a section of plant was done before optimising the heat network. The thermodynamic ideal heating and cooling energy targets of the heat network were 74 MW, which exceeded the actual energy use by 20%. The pinch point was 254.7 °C at a global minimum temperature of 30 °C. Retrofits were proposed to reduce this inefficiency and amount of excess heat for district heating was quantified. The retrofits were simulated in PRO/II software to analyse its impact on the entire heat network. The best-case scenario had a net present value of 51 MDKK over 15 years, with avoided emissions equal to 11.4 KTonsCO2 eq./year. Uncertainty analysis, done through Monte Carlo simulation, found that the Energy Targets were quite robust against the defined uncertainties.

Pinch analysis, as a technique to optimise the utilisation of resources, traces its beginnings to the 1970s in Switzerland and the UK – ETH Zurich and Leeds University to be more precise. Over four decades down the line, this methodology has entrenched itself in research circles around the world. While the technique was developed, to begin with, for energy (heat) recovery, it has since then expanded to embrace several other fields, and enabled optimisation of resource utilisation in general. The motive behind this article is to perform a focused, selective review of recent case studies from the developing world and transition economies, having ‘pinch analysis’ in their titles and thereby as their ‘core, crux and gist’, during the period 2008-2018. The resources focused on, include heat energy, electrical energy, water, solid waste, money, time, land (surface area), storage space (volume), human resources, mass of resources in general and hydrogen, while a handful of publications have their focus on carbon dioxide (greenhouse gases in general) emissions. Multi-dimensional pinch analysis promises to be an effective tool for sustainability analysis in the years to come; most importantly in the developing world where social well-being and economic development are priorities in the years ahead, and they ought to be attained by a simultaneous truncation of the environmental footprint, in other words, an optimisation of resource utilisation as well as adverse environmental impacts. In other words, the focus ought to be on sustainable production (efficiency) and consumption (sufficiency).

Syftet med det här examensarbetet är att undersöka möjligheter för energieffektivisering i form av ökad värmeåtervinning hos Ahlström-Munksjö Aspa Bruk AB med målet att föreslå åtgärder som minskar behovet av färskånga till uppvärmning i processerna. Detta har gjorts med hjälp av en pinchanalys där de externa behoven, pinchöverträdelser och effektiviseringsmöjligheter har identifierats och analyserats för att avgöra hur effektiv värmeväxlingen på Aspa Bruk är. Strömdata har samlats in på plats på bruket främst genom givare som loggar data kontinuerligt men även genom mätningar, miljöbesiktningsrapporter och antaganden. Ur pinchanalysen framkom det att de externa värmebehoven potentiellt skulle kunna reduceras med ca 19,2 MW, vid ett så energieffektivt system som möjligt, jämfört med dagens behov av färskånga som ligger på 71,5 MW. I praktiken är det dock inte möjligt att genomföra åtgärder för att minska det externa värmebehovet fullständigt till följd av tekniska- och ekonomiska begränsningar. Pinchöverträdelser står för ca 7,7 MW av de ca 19,2 MW och återfinns i sekundärvärmesystemet då det råder överskott av värme i varmvatten- och hetvattenproduktionen. De åtgärdsförslag som läggs fram bygger på att effektivisera energianvändningen och avlägsna pinchöverträdelser med åtgärder som anses genomförbara. Tre åtgärder presenteras: Använda värmeenergin från rökgaserna från sodapannan för att förvärma förbränningsluften till sodapannan och därmed ersätta delar av färskångan som används till detta. Öka andelen flashånga från tank 2 till förbasningsfickan där flisen förvärms innan kokaren istället för terpentinkondensorn. Detta skulle medföra en reducering av färskånga till förvärmningen av flisen. Eliminera 3 bars ångan till hetvattentanken och kompensera med ett ökat varmvattenflöde genom ett ökat intag av råvatten som ska bli varmvatten. Totalt skulle dessa åtgärder potentiellt kunna minska förbrukningen av färskånga med ca 12,5 MW. Potentiellt skulle även mer ång, The purpose of this master’s thesis is to investigate opportunities for a higher energy efficiency in terms of increased heat recovery at Ahlstrom-Munksjö Aspa Bruk AB with the goal of suggesting actions that reduces the need for live steam in process heating. In order to do this a pinch analysis was conducted where the utility consumptions, pinch violations and opportunities for increased energy efficiency were identified and analyzed in order to determine how efficient the heat exchange at Aspa Bruk is. Stream data was gathered at the mill mainly through continuously logging sensor data but also through measurements, environmental inspection reports and assumptions. From the pinch analysis it was discovered that the external hot utility potentially could be reduced by approximately 19,2 MW given that the system would be as energy efficient as possible, compared to the current need of live steam that is 71,5 MW. However, in reality it is not possible to accomplish this reduction due to technical and economic limitations. Pinch violations stand for about 7,7 MW of the 19,2 MW and are located in the secondary heat system since there is an excess of heat in the warm water- and hot water production. The actions suggested are based on increasing the efficiency of the energy consumption and removing pinch violations and are also considered feasible. Three suggestions are presented: Recover the heat in the fumes from the recovery boiler and use it to preheat the combustion air in to the recovery boiler and thereby replace some of the live steam used for this. Increase the amount of flash steam from tank 2 to the preheating of the woodchips before the boiler by reducing flash steam to the turpentine condenser. This would lead to a reduction in live steam used to preheat the woodchips. Eliminate the 3-bar live steam to the hot water tank and compensate it by increasing the amount of cold water that is going to become warm water. In total, these proposed arrangemen

The purpose of this project is to find an identification tag that can be used in a future automated pinch analysis tool. It can be used to further analyse composite curves and pinch results by tracking the original streams that was converted. In real life situations, retrofitting a process industries streams, can decrease heat demands and costs. A pinch analysis and a heat exchange network is created with fixed and flexible flows to show a recommendation on how the system model can handle this type of situations. The models have been created by hand with support from pinch literature and the calculations validated with mathematical software such as matlab and other graphing tools. The literature study and pinch modelling resulted in a recommendation of tagging Hstart and Hend for each individual stream. By using a geographical tag in a coordinate system the analyst will be able to find the original streams in the pinch analysis and composite curves. The project also resulted in a heating exchange network created from the fixed and flexible data set. The enthalpy differences between the ideal pinch result and the fixed data set is smaller than one might expect because of enthalpy abundance in the specific intervals.

Process industries in New Zealand use 214.3 PJ of process heat, of which approximately 65 % is fossil fuels. Despite increasing energy demands, depleting fossil fuel resources, and pressure to reduce Greenhouse Gas emissions, low grade heat in large-scale processing sites is still not fully utilised. This thesis presents methods to target, optimise and design more practical heat recovery systems for large industrial sites, i.e. Total Sites, and overcome technical limitations of current methods. Original contributions of this thesis to literature include novel developments and applications in six areas: i) a new Total Site Heat Integration (TSHI) targeting method – Unified Total Site Targeting (UTST) – which sets realistic targets for isothermal and non-isothermal utilities and heat recovery via the utility system; ii) a new TSHI optimisation and utility temperature selection method to optimise Total Cost of the utility system; iii) a new Utility Exchanger Network synthesis and design method based on the targets achieved by the UTST method and optimal temperatures from optimisation method; iv) a new method for calculating assisted heat transfer and shaft work to further improve TSHI cogeneration and performance; v) examination of heat transfer enhancement techniques in TSHI to achieve higher heat recovery and lower required area by substituting conventional utility mediums by nanofluids in the utility system; and vi) a spreadsheet software tool called Unified Total Site Integration to apply the developed methods to real industrial cases. The developed methods have been applied to three large industrial case studies. Results confirm that heat recovery and utility targets obtained from the UTST method were lower but more realistic to achieve in practice when compared to conventional TSHI methods. The three industrial case studies represent a wide variety of processing industries. In summary, the over-estimation of TSHI targets for the three case studies from using the

Syftet med det här examensarbetet är att undersöka möjligheter för energieffektivisering i form av ökad värmeåtervinning hos Ahlström-Munksjö Aspa Bruk AB med målet att föreslå åtgärder som minskar behovet av färskånga till uppvärmning i processerna. Detta har gjorts med hjälp av en pinchanalys där de externa behoven, pinchöverträdelser och effektiviseringsmöjligheter har identifierats och analyserats för att avgöra hur effektiv värmeväxlingen på Aspa Bruk är. Strömdata har samlats in på plats på bruket främst genom givare som loggar data kontinuerligt men även genom mätningar, miljöbesiktningsrapporter och antaganden. Ur pinchanalysen framkom det att de externa värmebehoven potentiellt skulle kunna reduceras med ca 19,2 MW, vid ett så energieffektivt system som möjligt, jämfört med dagens behov av färskånga som ligger på 71,5 MW. I praktiken är det dock inte möjligt att genomföra åtgärder för att minska det externa värmebehovet fullständigt till följd av tekniska- och ekonomiska begränsningar. Pinchöverträdelser står för ca 7,7 MW av de ca 19,2 MW och återfinns i sekundärvärmesystemet då det råder överskott av värme i varmvatten- och hetvattenproduktionen. De åtgärdsförslag som läggs fram bygger på att effektivisera energianvändningen och avlägsna pinchöverträdelser med åtgärder som anses genomförbara. Tre åtgärder presenteras: Använda värmeenergin från rökgaserna från sodapannan för att förvärma förbränningsluften till sodapannan och därmed ersätta delar av färskångan som används till detta. Öka andelen flashånga från tank 2 till förbasningsfickan där flisen förvärms innan kokaren istället för terpentinkondensorn. Detta skulle medföra en reducering av färskånga till förvärmningen av flisen. Eliminera 3 bars ångan till hetvattentanken och kompensera med ett ökat varmvattenflöde genom ett ökat intag av råvatten som ska bli varmvatten. Totalt skulle dessa åtgärder potentiellt kunna minska förbrukningen av färskånga med ca 12,5 MW. Potentiellt skulle även mer ång, The purpose of this master’s thesis is to investigate opportunities for a higher energy efficiency in terms of increased heat recovery at Ahlstrom-Munksjö Aspa Bruk AB with the goal of suggesting actions that reduces the need for live steam in process heating. In order to do this a pinch analysis was conducted where the utility consumptions, pinch violations and opportunities for increased energy efficiency were identified and analyzed in order to determine how efficient the heat exchange at Aspa Bruk is. Stream data was gathered at the mill mainly through continuously logging sensor data but also through measurements, environmental inspection reports and assumptions. From the pinch analysis it was discovered that the external hot utility potentially could be reduced by approximately 19,2 MW given that the system would be as energy efficient as possible, compared to the current need of live steam that is 71,5 MW. However, in reality it is not possible to accomplish this reduction due to technical and economic limitations. Pinch violations stand for about 7,7 MW of the 19,2 MW and are located in the secondary heat system since there is an excess of heat in the warm water- and hot water production. The actions suggested are based on increasing the efficiency of the energy consumption and removing pinch violations and are also considered feasible. Three suggestions are presented: Recover the heat in the fumes from the recovery boiler and use it to preheat the combustion air in to the recovery boiler and thereby replace some of the live steam used for this. Increase the amount of flash steam from tank 2 to the preheating of the woodchips before the boiler by reducing flash steam to the turpentine condenser. This would lead to a reduction in live steam used to preheat the woodchips. Eliminate the 3-bar live steam to the hot water tank and compensate it by increasing the amount of cold water that is going to become warm water. In total, these proposed arrangemen

The purpose of this project is to find an identification tag that can be used in a future automated pinch analysis tool. It can be used to further analyse composite curves and pinch results by tracking the original streams that was converted. In real life situations, retrofitting a process industries streams, can decrease heat demands and costs. A pinch analysis and a heat exchange network is created with fixed and flexible flows to show a recommendation on how the system model can handle this type of situations. The models have been created by hand with support from pinch literature and the calculations validated with mathematical software such as matlab and other graphing tools. The literature study and pinch modelling resulted in a recommendation of tagging Hstart and Hend for each individual stream. By using a geographical tag in a coordinate system the analyst will be able to find the original streams in the pinch analysis and composite curves. The project also resulted in a heating exchange network created from the fixed and flexible data set. The enthalpy differences between the ideal pinch result and the fixed data set is smaller than one might expect because of enthalpy abundance in the specific intervals.

[EN] Dryers are used for removal of moisture from an raw materials (such as effluent) to form a dried solids as per the requirements. For removal of the moisture, energy requirement is huge. Therefore, in this paper, methodology for heat recovery in one of the type of dryers as spray dryers is developed, which is simple and easy to apply. The proposed methodology is illustrated with the help of an example taken from literature. It is observed that the indirect heat recovery method could save energy maximum up to 82 % as compared to literature and 41 % higher than without heat recovery.

Process industries in New Zealand use 214.3 PJ of process heat, of which approximately 65 % is fossil fuels. Despite increasing energy demands, depleting fossil fuel resources, and pressure to reduce Greenhouse Gas emissions, low grade heat in large-scale processing sites is still not fully utilised. This thesis presents methods to target, optimise and design more practical heat recovery systems for large industrial sites, i.e. Total Sites, and overcome technical limitations of current methods. Original contributions of this thesis to literature include novel developments and applications in six areas: i) a new Total Site Heat Integration (TSHI) targeting method – Unified Total Site Targeting (UTST) – which sets realistic targets for isothermal and non-isothermal utilities and heat recovery via the utility system; ii) a new TSHI optimisation and utility temperature selection method to optimise Total Cost of the utility system; iii) a new Utility Exchanger Network synthesis and design method based on the targets achieved by the UTST method and optimal temperatures from optimisation method; iv) a new method for calculating assisted heat transfer and shaft work to further improve TSHI cogeneration and performance; v) examination of heat transfer enhancement techniques in TSHI to achieve higher heat recovery and lower required area by substituting conventional utility mediums by nanofluids in the utility system; and vi) a spreadsheet software tool called Unified Total Site Integration to apply the developed methods to real industrial cases. The developed methods have been applied to three large industrial case studies. Results confirm that heat recovery and utility targets obtained from the UTST method were lower but more realistic to achieve in practice when compared to conventional TSHI methods. The three industrial case studies represent a wide variety of processing industries. In summary, the over-estimation of TSHI targets for the three case studies from using the

Energy, exergy and advanced exergy methods were used to analyse a milk powder production facility. While a conventional energy analysis is used to map the energy flows and to suggest possibilities for process integration through pinch analysis, an exergy analysis identifies the locations and magnitudes of thermodynamic irreversibilities. The advanced exergy analysis determines the real potential for thermodynamic improvements by dividing the exergy destruction into its avoidable and unavoidable parts, which relate to technological limitations, and into its endogenous and exogenous parts, which present the interactions between the different sub-systems. This analysis was based on factory data with which the complete production line (milk treatment, evaporators and dryers) and the utility systems were modelled. The results show the potential for optimisation and a comparison of the applicability of the different methods to the dairy industry. The pinch analysis and energy mapping showed that the potential for heat integration was small. The exergy analysis revealed the gas burner and spray dryer caused most exergy destruction, while the heaters had low exergy efficiencies. The advanced exergy analysis found the evaporators to have a high share of avoidable exergy destruction. However not all results from the advanced exergy analysis were practical.

[EN] Dryers are used for removal of moisture from an raw materials (such as effluent) to form a dried solids as per the requirements. For removal of the moisture, energy requirement is huge. Therefore, in this paper, methodology for heat recovery in one of the type of dryers as spray dryers is developed, which is simple and easy to apply. The proposed methodology is illustrated with the help of an example taken from literature. It is observed that the indirect heat recovery method could save energy maximum up to 82 % as compared to literature and 41 % higher than without heat recovery.

This paper introduces a closed-loop dryer system to reduce the energy consumption for milk powder production. The system is based on a monodisperse droplet atomizer which reduces the amount of fines in the exhaust air, and allows dehumidification and recirculation of the air over the dryer. In this way the latent and sensible heat from the dryer exhaust are recovered. Two adsorbent systems for dehumidification are discussed; a membrane contactor with a liquid desiccant, and a zeolite sorption wheel. Four configurations for closed-loop spray drying are simulated and optimized. By heat integration of the adsorber-regenerator system with the dryer and preceding concentration step, the energy consumption is significantly reduced to 4.9 MJ heat per kg milk powder. The final heat integration solutions were obtained by simultaneous optimization of the operational conditions and the heat exchanger network based on pinch analysis. Industrial relevance: Drying is an energy intensive operation in processing. To comply with the upcoming regulations that arise from the EU goals for sustainable development, the energy consumption of drying processes should be reduced drastically. Emerging technologies are the key for the next step in energy efficiency improvement. A closed-loop spray drying system for milk powder production is simulated and optimized in this work. The proposed technologies are: monodisperse droplet drying, membrane contactor and a zeolite wheel. By applying air dehumidification and heat integration the latent and sensible heat are recovered from the exhaust air. The energy consumption for milk concentration and spray drying has the potential to be lowered from 8.4 to 4.9 MJ heat per kg milk powder. Although milk powder has been considered, the proposed system is also applicable to other food products, as well as in the (bio)chemical, pharmaceutical and paper industry.

[EN] Dryers are used for removal of moisture from an raw materials (such as effluent) to form a dried solids as per the requirements. For removal of the moisture, energy requirement is huge. Therefore, in this paper, methodology for heat recovery in one of the type of dryers as spray dryers is developed, which is simple and easy to apply. The proposed methodology is illustrated with the help of an example taken from literature. It is observed that the indirect heat recovery method could save energy maximum up to 82 % as compared to literature and 41 % higher than without heat recovery.

[EN] Dryers are used for removal of moisture from an raw materials (such as effluent) to form a dried solids as per the requirements. For removal of the moisture, energy requirement is huge. Therefore, in this paper, methodology for heat recovery in one of the type of dryers as spray dryers is developed, which is simple and easy to apply. The proposed methodology is illustrated with the help of an example taken from literature. It is observed that the indirect heat recovery method could save energy maximum up to 82 % as compared to literature and 41 % higher than without heat recovery.

[EN] Dryers are used for removal of moisture from an raw materials (such as effluent) to form a dried solids as per the requirements. For removal of the moisture, energy requirement is huge. Therefore, in this paper, methodology for heat recovery in one of the type of dryers as spray dryers is developed, which is simple and easy to apply. The proposed methodology is illustrated with the help of an example taken from literature. It is observed that the indirect heat recovery method could save energy maximum up to 82 % as compared to literature and 41 % higher than without heat recovery.

Denmark presents ambitious climate policies, and in order to fulfil these visions electrically driven large-scale heat pumps (HP) are often mentioned as an important technology for future district heating (DH) systems. To reach the high temperatures needed in current DH systems, the suggested HP installations become complex systems, where heat transfer between the HP cycle and the heat sink takes place at several temperature levels. In this study the heat exchanger network (HEN) between a HP installation consisting of two serially connected two-stage ammonia HP units and a heat sink being heated from 50 °C to 80 °C was investigated. The study applied pinch analysis to estimate the highest attainable Coefficient of Performance (COP) with the given HP configuration. Based on the result of the pinch analysis, a HEN reaching the highest COP was suggested and compared with COPs obtained with three other solutions for a HEN. The result revealed an estimated highest COP of 3.46. The three other design suggestions yielded reductions in the COP of -2.3%, -2.0%, and -1.8% compared to the highest. From this it was concluded that the HEN has an influence on the COP, and that the pinch analysis can be used to estimate the highest COP for a given HP installation. Furthermore, the COP obtained by practical installations was accordingly shown to come close to the target.

This work presents a systematic approach toward the design of Organic Rankine Cycles (ORC) for the generation of power from multiple heat sources available at different temperature levels. The design problem is approached in a mixed-integer non-linear programming (MINLP) formulation where an inclusive and flexible ORC model is automatically evolved by a deterministic algorithm for global optimization. The basic building block of the model is the ORC cascade which consists of a heat extraction, a power generation, a condensation and a liquid pressurization section. The aim of the optimization is to determine the optimum number of ORC cascades, the structure of the heat exchanger network shared among different cascades, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. The approach is illustrated through a case study which indicates that a system of two waste heat sources is best exploited through two interconnected ORC utilizing different working fluids.

This work presents a systematic approach toward the design of Organic Rankine Cycles (ORC) for the generation of power from multiple heat sources available at different temperature levels. The design problem is approached in a mixed-integer non-linear programming (MINLP) formulation where an inclusive and flexible ORC model is automatically evolved by a deterministic algorithm for global optimization. The basic building block of the model is the ORC cascade which consists of a heat extraction, a power generation, a condensation and a liquid pressurization section. The aim of the optimization is to determine the optimum number of ORC cascades, the structure of the heat exchanger network shared among different cascades, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. The approach is illustrated through a case study which indicates that a system of two waste heat sources is best exploited through two interconnected ORC utilizing different working fluids.

This work presents a systematic approach toward the design of Organic Rankine Cycles (ORC) for the generation of power from multiple heat sources available at different temperature levels. The design problem is approached in a mixed-integer non-linear programming (MINLP) formulation where an inclusive and flexible ORC model is automatically evolved by a deterministic algorithm for global optimization. The basic building block of the model is the ORC cascade which consists of a heat extraction, a power generation, a condensation and a liquid pressurization section. The aim of the optimization is to determine the optimum number of ORC cascades, the structure of the heat exchanger network shared among different cascades, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. The approach is illustrated through a case study which indicates that a system of two waste heat sources is best exploited through two interconnected ORC utilizing different working fluids.