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The reversible operation of a commercialized molten carbonate fuel cell as an electrolyzer is attractive to store the surplus of renewable energy and convert CO 2 into valuable fuel, like syngas (H 2 and CO). This work aims to assess this capability by developing a model for the co-electrolysis of CO 2 and H 2 O in the molten carbonate electrolysis cell (MCEC). Furthermore, a 1 MW power-to-gas system is simulated and optimized to maximize the process efficiency via a profound sensitivity analysis and a pinch heat integration analysis. The study's results reveal that when CO 2 electrolysis occurs, there is a risk of reaching the limiting current density at lower values, thus affecting the cell's performance. As for the simulation, the process yields an efficiency of 68.87% with an electrolyzer's power density of 0.082 W/cm2 per cell, producing 1.3 tons/day of methane gas ready for injection into the natural gas network. • Co-electrolysis of H 2 O and CO 2 in a molten carbonate electrolyzer was modelled. • 1 MW power-to-gas system is simulated and optimized via a sensitivity analysis. • Process yields an efficiency of 68.87% with 1.3 tons/day methane gas production. • The electrolyzer operates at a power density of 0.082 W/cm2 per cell. [ABSTRACT FROM AUTHOR]

In order to response to the “double carbon” strategy for reducing emissions, chemical production processes were optimized to lower the amount of utility work and equipment investment expenses with increasing the system’s capacity for heat recovery. A sensitivity analysis and the energy efficiency analysis with pinch technique were performed on the distillation and purification of the 30 kt/a isopropyl acetate (IPAC) production process by using process simulation software of Aspen Plus. The IPAC refining tower optimization results show that the purity of the refined IPAC could be reached 99.9% at circumstances of 44 theoretical plates, 19 feed plates, and 0.755 reflux ratio. According to the optimized energy consumption data from Aspen Energy Analyzer (AEA), the cold and heat logistics matching was performed. It can be seen that the heat exchange network was tuned to maximize energy recovery by reducing the amount of utility work. The optimized cold and heat utility usage were 734.69 and 727.81 kW, which meaning that compared with original process, the cold and heat utility usage energy can be save with 10.0%, respectively. The optimized results provide a certain theoretical basis and solution for improving energy saving and reducing investment costs. [ABSTRACT FROM AUTHOR]

Spray drying systems with heat recovery have gained prominence in recent times due to the energy crises and changing weather conditions. These systems are widely used in various industries, including chemical, food, fertilizer, and pharmaceutical, but their energy-intensive nature calls for efficient operation and heat retrieval. This review article discusses the current developments in heat recovery methods, including direct, indirect, and hybrid systems, as well as improvements in dryer efficiency and thermal optimization techniques. Pinch and exergy evaluations are extensively investigated as they play a crucial role in heat integration design and analysis. Recovering heat from the exhaust stream of spray dryers poses challenges due to fouling caused by fines in the exit stream and the selection of analysis methods. Exploring non-conventional energy sources like solar and geothermal energy shows potential for drying operations, but further research is needed for design and control. The adoption of recovery options has led to a 35% improvement in energy efficiency and around 74% energy savings in specific cases. [ABSTRACT FROM AUTHOR]

Trinidad and Tobago's (T&T) conditional commitment to the Paris Agreement requires an overall power emission avoidance (EAT) of 28.7 MtCO2-e from Business-As-Usual by 2030, dependent on international financing. T&T has outlined several initiatives to achieve this, including zero-carbon renewable energy (RE) introduction. However, other technologies such as Carbon Capture and Storage (CCS) can also be used in support of achieving EAT. Using a specific scenario (S3), this study assesses the techno-economics of CCS within the sector to minimize the requirement of RE using a carbon measuring tool called Carbon Emission Pinch Analysis (CEPA) to achieve EAT. Local power plants were screened, and a CCS retrofit was then technically designed using a validated software called Aspen HYSYS. Multi-period CEPA methodology was then applied to quantify ∼17% of grid energy from RE along with CCS to achieve EAT. Economic models were also used to determine the grid unit cost of emission abatement for S3 to be 64 USD/tCO2-e; a doubling of initial projection requirements. With T&T's current dynamics, these findings can help guide actions to reduce the requirements of RE onto the grid through the supplemental introduction of CCS to achieve its EAT. [ABSTRACT FROM AUTHOR]

• Energetic and exergetic analysis of a TC-HTHP cycle configurations. • Gas-cooler pinch point analysis of a TC-HTHP cycle. • Environmental impact of operating a TC-HTHP within an industrial process. • HC-600 (Butane) demonstrated the highest VHC values and, therefore, the smallest size of compressor. Sub-critical mechanically driven industrial heat pump technologies have gained momentum in recent years with systems capable of supplying temperatures up to 150°C. Extending the operating envelope using heat pump technologies to and beyond 200°C requires an innovative shift towards transcritical techniques to meet the demands of a broader range of industrial processes. Transcritical high-temperature heat pumps (TC-HTHPs) pose many technical and operational challenges requiring research and development to evaluate operational performance. This paper assesses the feasibility of operating a HTHP system to achieve 200°C heat sink temperatures using suitable low GWP refrigerants. The work investigates three different TC-HTHP cycle configurations using a steady-state theoretical model to compare and evaluate energetic, exergetic and environmental performance. In addition, cycle performances for this study are obtained at the optimum pressure for the gas cooler in which the maximum COPs are achieved. The results reveal that the basic cycle with dual internal heat exchanger (IHX) was the most efficient configuration, with HFO-514A and HFO-1234ze(Z) refrigerants identified as the most promising candidates for TC-HTHP systems. Configurations employing HCFO-1233zd(E) exhibited a trade-off between high energetic and exergetic efficiency while providing an A1 safety group classification. A pinch point analysis of the gas cooler demonstrated the need to optimise the overall length to achieve increased operational performance at very high glide temperatures. An evaluation of the environmental impact identified reductions in TEWI value by up to 20 % for the refrigerants tested over HFC-245fa. This study provides a basis for future practical activities of TC-HTHPs using eco-friendly candidates. [ABSTRACT FROM AUTHOR]

The number of data centres (DC) in recent years is growing rapidly, and with that, the share in total consumption of electricity is growing too. A significant amount of electricity is transformed into heat energy which increases the optimal temperature in DC for component operation. This heat needs to be removed and usually, it doesn't have any further application. Today it is recognized that waste heat can be integrated into district heating (DH) and by using it reduce the usage of conventional heat fuels. Integration of waste heat is possible in three ways: with a heat exchanger (HEX), with a booster heat pump, or with the combination of the HEX and heat pump. In this paper, a combination of HP and HEX was used. Although those utilizations are examined and implemented, there is a lack of research on the optimization of the integration of waste heat into the district heating network (DHN). To perform optimization, a thermodynamic model of the DC and a pinch analysis model were developed. In this study, a method for evaluating the economic feasibility of DC waste heat integration into DH systems is proposed. The most suitable integration technology of waste heat into DH systems by using the hourly merit order of waste heat utilization technologies based on pinch analysis is found. The connection pipe between DC and DHN is optimized, and the ideal diameter is determined considering different temperature regimes of the network: low-temperature, ultralow temperature, and neutral temperature networks. The methodology was tested using a case study of a DC in the City of Zagreb. [ABSTRACT FROM AUTHOR]

In this research work, an attempt has been made to address the heat and power integration opportunities for the process of the chlorination of benzene. This process produces a mixture of chlorobenzenes. To increase the production of the dichlorobenzene portion, the ratio of chlorine to benzene is typically 2:1. A process simulation model is designed using Aspen Plus for the production of 70,000 tons/year of dichlorobenzene via the reaction of liquid benzene with gaseous chlorine. Energy analysis is performed for the effective utilization of the utilities by networking the heat exchangers. This modification reduced the process heating and cooling requirements by 56.7% and 12.7%, respectively, and a reduction by 35.4% in the operating costs is achieved, while the annualized fixed cost increased by 9.6%; these changes resulted in savings in the total annual costs of about 10.9%. [ABSTRACT FROM AUTHOR]

Energy cost represents a significant part of the total operating costs of many processing units. Crude distillation is an energy intensive process. Energy integration is a typical solution to reduce heating and cooling utilities through maximizing the target temperature of crude oil streams before entering the furnace. Over the past few decades, significant progress has been made in energy integration methods including pinch technology and mathematical programming approaches. Very recently, graphical techniques have been developed for revamping studies and energy analysis. Such diagrams are valuable in energy targeting to identity energy inefficiencies and are key to potential modifications for maximum energy integration. The current research applies the recent graphical revamping methodology on an existing crude atmospheric distillation unit. The unit is located in north of Egypt (Suez region) and is operated under two different operational modes; (1) without naphtha stabilizer; the process reformer is in operation to reform all naphtha streams without stabilization and (2) with naphtha stabilizer; LPG is separated from naphtha stream. A graphical-based revamping methodology is applied to retrofit the existing preheat train. The revamping procedure starts by simulating the existing HEN data, followed by validation against the real data. The current performance of the HEN is analyzed using the graphical axes of Thot-Tcold diagrams. The graphical method is then used to identify exchangers across the pinch and recognize the potential modifications to improve the energy performance and reduce fuel consumption. Implementing the graphical identified modifications on the plant resulted in the following benefits: (1) when stabilizer is in operation, energy savings are achieved by 21.1% with additional capital investment of 0.81 MM$ and annual energy savings of 0.82 MM$, with a payback period of one year. (2) when reformer is in operation, the energy savings are 0.42 MM$ with capital investment of 0.33 MM$. The methodology results provide a flexibility in refineries operations.

The actual task of the state is to increase the energy efficiency of the oil refinery. The object of research is a vacuum distillation unit, including a preheating unit for raw materials and a furnace for heating fuel oil before the column. Pinch analysis allows to analyze and optimize a large number of heat flows. In this study the analysis and enhancement of efficiency of the research object is carried out by enthalpy pinch analysis. In order to reduce the heat load of the furnaces, the additional flows were introduced into the heat exchange system of the oil heating unit. Parametric optimization of the new heat exchange system was carried out. The minimum needs of the heat exchange system in external energy carriers are determined. An enthalpy cascade of the heat exchange system has been constructed, which clearly shows the distribution of heat between each heat flow of the system. In the analysis of the energy efficiency of a furnace, an important point is the determination of the optimal heat capacity of the combustion products. In this work, we have determined the optimal flow heat capacity, at which the heat loss with the exhaust gases is minimal. As a result of the studies carried out, the efficiency of the fuel oil preheating unit has been increased by maximizing heat recovery, and the cost of external energy carriers has been minimized. By reducing heat loss with flue gases, it was possible to increase the efficiency of the furnace.

The chemical industry is acquiring new advancement day by day. Previously, quite massive equipment had been used to do heat transferring tasks, but now the industry has been modernised. Heat Integration is a trending area of study that might be applied in several sectors to redesign processes. Heat Integration alludes to any technique in chemical engineering that results in considerably smaller, greener, and more energy-efficient appliances. Heat Integration aims to improve energy transfer, lowering the equipment’s capacity for heat transfer. This paper uses pinch analysis to optimize heat integration and find the best heat-exchange network through case studies. Pinch Technology offers a systematic approach to reducing energy use across all sites and activities. It is feasible to determine the proper alterations to the fundamental process parameters that can result in energy savings by using pinch technology. The Aspen Energy Analyzer tool has been used to compute the heat integration of the case studies. After obtaining the data from the software, they were used in pinch analysis to determine the optimal alternative for the heat exchanger network. [ABSTRACT FROM AUTHOR]

The effective utilization and conservation of energy are crucial challenges in industrial process systems. The chemical engineering industry is actively researching the integration of processes via heat exchanger networks synthesis. The strategy presented in this work utilizes recent advancements in pinch technology to investigate the impact of minimum approach temperature variation on energy and capital costs. The multi-objective problem considered in this approach involves minimizing utilities of heating and cooling, minimizing the area of heat exchanger, minimizing irreversibility, and maximizing effectiveness. The technique of order preferences by similarity to an ideal solution (TOPSIS) is applied to determine the optimal heat exchanger network based on the compromise solution concept, which is achieved by selecting the network having the closest Euclidean distance to the perfect solution. The practicality of this methodology is validated by resolving two distinct cases, the first case involve ten streams, the second industrial case is a separating crude oil into its primary constituents namely naphtha, kerosene, diesel and residue which demonstrate that this technique can provide more practical solutions compared to prior literature. Additionally, the study reveals that the novel approach can identify other multi criteria decision making problems with a discrete number of alternatives, criteria and are more cost-effective networks than those produced by alternative techniques. [ABSTRACT FROM AUTHOR]

Hydrogen has been considered a future energy carrier for decades and the demand for hydrogen in refineries is always upward due to the revival of new technologies. The steam methane reforming method is frequently employed because of its high hydrogen generation efficiency at a cheap cost and minimal environmental footprint. However, depending on the type of feedstock, one unit of hydrogen generates 9e10 units of CO2 that need to be treated for environmental sustainability. Therefore, the optimization of hydrogen production and CO2 capture is critical to address the issue. The simulation research was conducted to anticipate and optimize steam reforming using Aspen HYSYS. A conversion-type reactor was used to develop this simulation-based model. The primary goal of this work is to investigate and optimize hydrogen production efficiency while mitigating CO2 by varying process parameters. The CO2 capture efficiency was investigated at the different yields for hydrogen production and a maximum of 98.8 % absorption of the CO2 was achieved using the carbon capture system proposed in the current study. Later, the Aspen Energy Analyzer tool revealed potential improvements for energy and cost optimization. [ABSTRACT FROM AUTHOR]

It is important to estimate the energy required in ore processing to select the most affordable and efficient energy system for the integration of renewable resources into the mining industry. In the present work, the energy consumption for the concentrate of tungsten ore in Mongolia was theoretically predicted based on operational variations (particle size and the hardness of the tungsten ore) and different equipment. The energy was in the range from 0.48 to 1.32 kWh/t for the crushing stage, and a cone crusher was more suitable than a jaw crusher due to the particle size of feed material and product. The required energy in the grinding stage was from 6.22 to 11.88 kWh/t using a SAG mill or from 3.04 to 7.39 kWh/t using a ball mill. The further separation by a flotation consumed 4.83 kWh/t or by a shaking table consumed 1.29 kWh/t. The maximum energy consumption per hour for the whole process was estimated to be 2–3 MW, which was better to integrate with a hybrid renewable energy system. The sizing method Power Pinch Analysis was used to estimate the electric supply based on the combination of wind, biomass and solar resources, which was sufficient for the demand from the predicted range of energy. [ABSTRACT FROM AUTHOR]

Ventilation heat loss is one of the most important factors contributing to energy performance of greenhouses. This paper suggests a systematic method based on dynamic pinch analysis (PA) to design an integrated heating, cooling, and ventilation system that uses ventilation waste heat in a cost-effective and energy efficient way. A heat recovery system including an air handling unit, borehole thermal storage, and a heat pump is proposed to investigate all heat integration scenarios for an entire year. In the first step, the heat integration scenarios are reduced to a few typical days using a clustering technique. Then, a generic methodology for designing a heat exchanger network (HEN) for a dynamic system, ensuring both direct and indirect heat recovery, is presented and a set of HENs are designed according to the conditions of typical days. Afterwards, the best HEN design is selected among all design alternatives using a techno-economic analysis. The whole procedure is applied to a commercial greenhouse and the best HEN configuration and required equipment sizes are calculated. It is shown that the best-performing design for the greenhouse under study produces primary energy savings of 57%, resulting in the shortest payback period of 9.5 years among all design alternatives. [ABSTRACT FROM AUTHOR]

The present paper proposes ways to reduce energy consumption during naphtha isomerization and catalytic reforming by optimizing the recovery heat exchange of the feed preparation unit using pinch analysis. A pinch analysis procedure based on heat flux integration was carried out in three stages. At the first stage, information on the technological and energy characteristics of the unit was collected and studied. At the second stage, options for improving the energy efficiency of the unit were determined. At the third stage, a detailed study of technical solutions for optimizing the flow scheme of recovery heat exchange was performed along with an economic justification. Proposed options for modernizing the existing industrial unit are based on the set of positive values for economic indicators and criteria of the program for improving the operational efficiency. The presented heat exchange system layouts can be used in the design and modernization of secondary naphtha distillation units at oil and gas refineries. [ABSTRACT FROM AUTHOR]

The development of technologies for utilizing biomass has attracted attention because biomass can be produced sustainably worldwide. Biomass‐derived 2‐methyltetrahydrofuran (MTHF), which is a promising alternative to gasoline, has great market potential and a growing demand. However, in conventional biomass conversion processes, the minimum selling price (MSP) of biochemicals is not economically acceptable. Co‐production of biochemicals can increase the economics of biomass utilization. Herein, we developed a process for co‐producing MTHF and 1,4‐pentanediol (1,4‐PDO) from lignocellulosic biomass. After biomass fractionation, cellulose and hemicellulose were converted to levulinic acid (LA), and lignin was used for heat and electricity generation. LA was then converted to γ‐valerolactone (GVL). As a platform material for co‐production, GVL was converted into MTHF and 1,4‐PDO in each subsystem. The split ratio of GVL was controlled to efficiently produce MTHF and 1,4‐PDO according to market conditions. Additionally, we performed a techno‐economic and life‐cycle assessment (TEA and LCA, respectively) for the developed process. The MSP of MTHF was calculated based on the TEA results, and the environmental impacts were quantitatively calculated based on the LCA results. We performed heat integration using pinch analysis and then reduced the energy requirement of the proposed process. The key cost drivers and environmental factors of the proposed process were identified via sensitivity analyses. Consequently, during the processing of 2000 ton/day of corn stover (raw material of lignocellulose), the MSP of MTHF was calculated as $2.64/GGE (gasoline equivalent), and representative environmental impacts such as climate change and fossil depletion were calculated as −0.296 kg CO2 eq and − 0.056 kg oil eq, respectively. As a result, we can increase the economics of commercial production of MTHF and 1,4‐PDO with environmental sustainability. The proposed process can serve as a potential solution to the growing demand for the need for more sustainable biomass utilization. [ABSTRACT FROM AUTHOR]

This paper studies the combined heating and cooling thermal performance of a CO2 heat pump system considering the subcooling effect. For such a system without cold thermal energy storage (CTES), the gas cooler outlet temperature normally needs to be controlled to match the cooling load required. However, the integration of CTES would enable the system to be operated under its optimal conditions depending on the ambient temperatures, i.e. a considerable amount of cooling capacity can be generated and stored for later use. A configuration of a CO2 heat pump integrated with CTES is described in this paper. A thermodynamic cycle and a simulation model considering the subcooling effect have been developed. The mathematical model for the pinch point analysis has been newly validated against published experimental data with acceptable agreements. In the case study, the impacts of the subcooling temperature on the optimal combined performance under four ambient temperatures (5 °C, 15 °C, 25 °C, and 32 °C) have been studied. The highest optimal combined COP of 5.38 can be achieved when the ambient temperature is 5 °C. The detailed profiles of CO2 temperatures, heating and cooling loads, and the COPs when the CTES is in operation have been revealed for the first time. It is found when the ambient temperature is higher than the water inlet temperature (plus the pinch point temperature), the optimal cooling COPs can even have a surge without the subcooling effect, due to a lower sCO2 temperature leaving the heat exchanger compared to the ambient temperature. Additionally, performance analysis for the CO2 heat pump system with or without CTES is compared, and it is concluded that all optimal heating, cooling, and combined COPs integrated with CTES surpass those without CTES. [ABSTRACT FROM AUTHOR]

Energy efficiency and process integration play a vital role in minimizing fossil fuel consumption and electricity demand within industrial processes. Therefore, experts have prioritized research on enhancing and promoting the thermal energy efficiency of this sector, with a specific emphasis on energy recovery and sustainability goals. Pinch analysis (PA) and exergy analysis (ExA) have been employed separately or in conjunction to optimize energy recovery and minimize the work potential losses (exergy loss). This paper demonstrates the effectiveness of a developed algorithm that handle the impact of ΔTmin on energy and exergy targets in an automatic manner through a set of scripts. The scripts manipulate input data and intermediate data through loops in order to quantify and determine different energetic and exergetic quantities. The developed algorithm is testified using a literature case study in order to prove its validity. For δTmin in range [0,10] and step s = 2, the algorithm performs the calculations for each δTmin in range ΔTmin. The obtained results include the pinch analysis parameters such as the global pinch point temperature [Tpinch] as well as the minimum heating and cooling requirements ([Uhot] and [Ucool]). For the scripts devoted to the exergy concept, the algorithm determines all the exergy targets (rejection, requirement and avoidable losses). As a result for δTmin in ΔTmin, the process external utilities Uhot and Ucool increased simultaneously from 6.85 and 4.39 MW to 12.2 and 9.75 MW with increment of δTmin, which means that the energy recovery and avoidable exergy losses reduced with respect to δTmin. For the exergy requirement and rejection targets, they increased simultaneously from 2.6602 and 1.3231 MW to 6.711 and 2.88 MW with δTmin increment, indicating the opportunity to design a system to recover work through turbine expansion. In addition to the originality of the interconnected scripts, the obtained results are in accordance with those in the literature, indicating the applicability of the developed algorithm. [ABSTRACT FROM AUTHOR]

Canada has made a commitment in the Paris Agreement to reduce its total greenhouse gas emissions by 40–45% from 2005 levels by year 2030 and achieving net-zero emissions by year 2050. An enhanced target has been established for the electricity sector, aiming to achieve a reduction of 88% from 2005 levels by 2030. Achieving these ambitious targets requires the implementation of new CO2 reduction measures and policies. In this work, carbon emissions pinch analysis (CEPA) is used for planning energy resources in the electricity sector while aiming to achieve both country and regional targets. Different scenarios are proposed for years 2030 and 2050 based on current policies and extension of some realistic assumptions, including the use of carbon capture and storage (CCS) facilities, negative emissions technologies (NETs), and increased capacity for renewable energy sources. In year 2030, the proposed solution indicates that the reduction of CO2 emissions of 3.1 Mt CO2-eq. is achievable, which is lower than the country target of 14 Mt CO2-eq. This solution can serve as the benchmark for each stakeholders at provincial level to reach their regional target. Results also show that electricity and CO2 trading are required to meet the energy requirement and to achieve the year 2030 CO2 emissions reduction goal at the provincial level which is the novelty of this paper. Although none of the cases has met net-zero emissions in year 2050, they do demonstrate that net zero is not far from materialisation. [ABSTRACT FROM AUTHOR]

The evaporation station is at the center of the energy balance of sugar mills. The objective was to propose a methodology for the energy evaluation of the evaporation station that complements the methods for energy management in sugar mills; in correspondence with the energy management system (EnMS) based on the ISO 50001 standard and its complementary standards. The methodology was structured according to the PDCA cycle of Continuous Improvement (Plan-Do-Check-Act), a recurrent process to improve energy performance. The methodology takes into account the contributions and overcomes limitations of existing methodologies. It incorporates methods and criteria for developing an energy review; considers the impact of evaporation station design, construction and operation on energy efficiency; and emphasises the synergy between the methods of energy analysis, exergy analysis, process integration (Pinch Analysis). It constitutes a methodological contribution that strengthens the energy review of the evaporation station, allowing the exhaustive analysis of the problem and the relevance of improvements to increase energy efficiency; and complements existing methods for energy management in sugar mills. [ABSTRACT FROM AUTHOR]

It is important to properly account for the emissions contribution of process units in order to develop cost-effective industrial decarbonization strategies. However, there is limited literature on this topic in the edible oil refining sector. This work addresses this research gap by developing a novel systematic technique for assessing decarbonization options in the palm oil refining process. This technique combines enterprise input-output analysis (EIOA) with graphical carbon emission pinch analysis (CEPA) into a unified approach to examining cost-effective decarbonization measures. Results show that the average carbon intensity of the system was 0.0432 kg CO 2 /$ while the total carbon footprint was 2339.97 kg CO 2. Palm fatty acid distillate (PFAD) has the highest carbon intensity contribution (0.0392 kg CO 2 /$) among the multiple products. Four scenarios to achieve a 20% reduction in CO 2 emissions based on heat integration and process changes were examined. Economic evaluation was also conducted for each proposed strategy. • An integrated EIO-CEPA technique was developed for industrial decarbonization. • The technique was applied on a palm oil refining process. • Carbon intensity reduction of 20% was set as a benchmark. • Four decarbonisation scenarios were analysed along with their economic feasibility. [ABSTRACT FROM AUTHOR]

Microalgae are the third generation of biomasses that have received lots of attention due to their high energy content and ability to capture carbon dioxide from the air. However, there are some techno-economic challenges for their world commercialization. A variety of fuels can be extracted from microalgae, and in addition to these fuels, algae by-products can be used to commercialize this industry. Various processes will be performed on microalgae to finally desired products can be extracted. In this research, an integrated system has been designed for the simultaneous production of ethanol, methane, and hydrogen from Chlorella vulgaris microalgae. The results showed that after culturing, harvesting, and increasing the concentration of the solution in addition to the main products such as ethanol, methane, and hydrogen, by-products including acetic acid, methyl acetate, ethyl acetate, furfural and etc. can be utilized for commercializing microalgae industry. Also, another purpose of this study is to apply Pinch Analysis to the mentioned system, which will ultimately improve the concentration of microalgae in the photobioreactor. The results of Pinch Analysis show that by increasing the concentrations of microalgae, carbon dioxide, and nutrients in the photobioreactor inlet up to 2.35 gr/l, the desired amount of demands can be met by the new supplies. [Display omitted] • Designing a simultaneous production process of ethanol, methane and hydrogen. • Modifying the production of biofuels and value-added materials from the microalgae. • Doing mass balance analysis, energy balance analysis and mass pinch analysis. [ABSTRACT FROM AUTHOR]

The development of process flow diagrams requires knowledge of reaction enthalpy for pinch analysis and thermal risk assessment. Such information is missing for some biomass processes, such as the production of γ-valerolactone (GVL) from the hydrogenation of levulinic acid or alkyl levulinate. To fill this gap, this manuscript describes a detailed calorimetric study on the hydrogenation of levulinic acid (LA), methyl levulinate (ML), ethyl levulinate (EL), propyl levulinate (PrL), butyl levulinate (BL) and pentyl levulinate (PeL) over Ru/C. This reaction system occurs through a two-step pathway with a domino hydrogenation/cyclization sequence. The cyclization step (lactonization) was found to be endothermic and was evaluated by a Tian-Calvet C80 micro-calorimeter, whereas the hydrogenation step was found to be exothermic and was tracked by a RC1 Mettler Toledo High-Pressure calorimeter. It was verified that reaction enthalpy is independent of reaction temperature (in the operating conditions used in this work), levulinate concentration and solvent (levulinate, corresponding alcohol or GVL). It was also found that reaction enthalpy for both steps did not depend linearly on alkyl chain length. [Display omitted] • Hydrogenation enthalpy for alkyl levulinates was determined. • Cyclization enthalpy for alkyl 4-hydroxypentanoate was obtained. • Reaction enthalpies for hydrogenation of alkyl levulinates are independent of operating conditions. • No linear correlation between alkyl chain length and reaction enthalpy was observed. [ABSTRACT FROM AUTHOR]

Uncertainties are widely present in the design and simulation of aero-engine combustion systems. Common non-probabilistic convex models are only capable of processing independent or correlated uncertainty variables, while conventional precise probabilistic sensitivity analysis based on ideal conditions also fails due to the presence of uncertainties. Given the above-described problem, an imprecise p-box sensitivity analysis method is proposed in this study in accordance with a multi-dimensional parallelepiped model, comprising independent and correlated variables in a unified framework to effectively address complex hybrid uncertainty problems where the two variables co-exist. The concepts of the correlation angle and correlation coefficient of any two parameters are defined. A multi-dimensional parallelepiped model is built as the uncertainty domain based on the marginal intervals and correlation characteristics of all parameters. The correlated variables in the initial parameter space are converted into independent variables in the affine space by introducing an affine coordinate system. Significant and minor variables are filtered out through imprecise sensitivity analysis using pinching methods based on p-box characterization. The feasibility and accuracy of the method are verified based on the analysis of the numerical example and the outlet temperature distribution factor. As indicated by the results, the coupling between the variables can be significantly characterized using a multi-dimensional parallelepiped model, and a notable difference exists in the sensitivity ranking compared with considering only the independence of the variables, in which input parameters (e.g., inlet and outlet pressure, density, and reference flow rate) are highly sensitive to changes in the outlet temperature distribution factor. Furthermore, the structural parameters of the flame cylinder exert a secondary effect. [ABSTRACT FROM AUTHOR]

Heat integration by pinch method is used to modify the heat exchanger network of an industrial ethylene glycol plant. The aim is to reduce the energy cost by operating the plant close to the maximum energy recovery. Pinch analysis identified a pinch temperature of 483 K, a minimum heating utility of 13,490.9 MJ/ton EO, and a minimum cooling utility of 25,697 MJ/ton EO. Using the pinch decomposition diagram and the standard procedure for matching hot and cold streams, a retrofit of the heat exchangers network is developed. The modified heat exchanger network reduces the external cooling duty by 45.5% and the external heating duty by 93.3%. This promising cost savings provide enough justification for restructuring the existing ethylene glycol plant. Moreover, an additional 6% reduction in the external cooling duty can be achieved by integrating the steam turbine below the pinch point.

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Bioadsorbents based on biopolymers modified with magnetic nanoparticles stand out for being non-toxic, effective, and easy to recover. Thus, the objective of the present work was to carry out a computer-aided environmental evaluation of the industrial-scale production of bioadsorbents from chitosan modified with iron nanoparticles and functionalized with thiourea as a chelating agent plus mass integration. The plant simulation was carried out in Aspen Plus, and for the mass integration of the process, a pinch analysis was used to determine the minimum target fresh and residual water amount, assuming two process stages: (1) the synthesis of magnetite nanoparticles, and (2) the production of chitosan-based bioadsorbents. The environmental assessment was performed using the waste reduction algorithm (WAR). The potential environmental impact (PEI) was quantified, taking into account the impact of the products and energy, obtaining a value below zero of −0.78 PEI/kg of the product. The photochemical oxidation potential (PCOP) stood out as the category with the greatest impact, mainly related to the use of ethanol during washing. The categories related to toxicological impacts (HTPI, HTPE, TTP, and ATP) had lower values than those related to atmospheric impacts (GWP, ODP, PCOP, and AP). The mass integration of the process resulted in fewer impacts in the HTPE category, as a consequence of the decrease in NaOH in the residual streams and the release of 0.297 PEI/kg of product in the ATP category caused by the presence of Al(OH)₃. It can be concluded that the mass integration managed to reduce up to 51% of the freshwater used in the processes, and it is a useful tool, as it slightly decreased the total potential impacts. [ABSTRACT FROM AUTHOR]

Due to water scarcity over the globe finding ways of re-using wastewater is becoming more and more essential so as to put less strain upon natural resources. This paper provides new insights in particular by introducing for the first time the necessity of taking a balanced approach when using pinch analysis; cooling water demand can be as important as energy demand for inland locations particularly when externalities are taken into account. This is particularly important for Kazakhstan which is a dry, inland country, where climate change is exacerbating issues around water usage. Recent sharp reductions in the flow of the Zhayik river in the Atyrau region of Kazakhstan has magnified the water shortage in the Atyrau region and forced the government to develop new water policies to address this most urgent and serious matter. This paper analysed the water consumption of the main water consumers, the Atyrau oil refinery (AR) with respect to the country's other refineries and found that there has been a significant performance gap. Recently modernisation at AR has sought to transition it from open loop wastewater treatment to closed loop wastewater treatment. Not only has this significantly reduced the water intake from the Zhayik river but there is now zero discharge to the evaporation ponds. Eliminating this discharge prevents soil and groundwater contamination. Conventional methods of wastewater treatment within the framework of modernisation project, called "Tazalyq", are able to remove the majority of contaminants. However, this is still not sufficient to deal with small stable oil droplets (<5 µm). Methods to further enhance the treatment such as membrane technology and segregation are discussed. The former can concentrate small stable droplets without further use of chemicals, and the permeate is quality water that can be recycled. Pilot plant results on the use of reverse osmosis to treat blowdown water are also included. Implementation of this process would reduce water demand by circa 10%. Such an addition to modernisation project would further reduce the water intake from Zhayik river. [ABSTRACT FROM AUTHOR]

Enormous amounts of raw materials are consumed through various industrial processes worldwide. Vast amounts of raw materials utilized by the chemical industry typically go to waste. Mass integration is a distinctive method of streamlining the consumption of raw materials in chemical industries. Mass integration was developed by employing principles of pinch analysis in order to optimize mass exchange networks. To apply the concepts of mass integration, this work introduces a Matrix Laboratory (MATLAB) code designed on the bases of the composition driving force graphical design approach. This MATLAB code was devised to analyze details of mass transfer operations with the lowest number of calculations possible. The algorithm’s detailed coding allows for designing mass exchange networks above and below the pinch. For maximum mass recovery, pinch principles were employed, and were delivered in an educational manner to students and young researchers in the field. The MATLAB code was designed to develop a useful toolbox for process integration as well as determine the number of plates required for each mass exchanger. The model was tested at pyrolysis plant with the aim of achieving mass targets and optimum matches for maximum recovery at the lowest costs possible.

The proton-conducting solid oxide electrolysis cell (H-SOEC) is a clean technology for syngas production from H 2 O and CO 2 through electrochemical and chemical reactions. However, it provides a low CO 2 conversion and produces a syngas product with a high H 2 O content. To improve the H-SOEC for syngas production, H-SOEC coupled with a dry methane reforming process (H-SOEC/DMR) was proposed in this work. The process flowsheet of the H-SOEC/DMR was developed and further used to evaluate the performance of the H-SOEC/DMR process. From the performance analysis of the H-SOEC/DMR process, it was found that the CO 2 and CH 4 conversions were higher than 90% and 80%, respectively, when the process was operated in the temperature range of 1073–1273 K. In addition, the result showed that a syngas product with a low H 2 O content could be obtained. Energy efficiency was then considered and the results indicated that the highest energy efficiency of 72.80% could be achieved when the H-SOEC/DMR process was operated at a temperature of 1123 K, pressure of 1 atm, and current density of 2500 A m−2. Based on a pinch analysis, a heat exchanger network was applied to the H-SOEC/DMR process that improved the energy efficiency to 81.46%. Finally, an exergy analysis was performed and showed that the H-SOEC/DMR unit had the lowest exergy efficiency as a high-temperature exhaust gas was released. [Display omitted] • The syngas production from H-SOEC is improved by incorporating with DMR. • The obtained syngas product has a high H/C molar ratio of 2 with less amount of H 2 O. • Increasing temperature can reduce the cell voltage and enhance syngas product. • The implementation of heat exchanger network can enhance the energy efficiency to 81.46%. [ABSTRACT FROM AUTHOR]

• Light gas separation unit of MTP process and refrigeration cycles are simulated. • A new multi-objective optimization approach for minimizing TAC with achieving to the desired product specifications is applied. • Pinch and exergy methods are used for obtaining optimal results in columns and refrigeration cycles operating conditions. • Real costs of refrigeration cycles considering of their interactions with separation columns are calculated. • Operating parameter of the propylene and ethylene refrigeration cycles are optimized simultaneously with distillation columns. In this study, optimization and economic analysis of the separation of light gases in the methanol to propylene, MTP, process along with refrigeration cycles design are performed, by using pinch and exergy analysis. In the course of the separation process optimization and refrigeration cycles design, by using a Visual Basic, VB, program and genetic algorithm, GA, rigorous distillation simulation is carried out, then streams information is employed to find optimum temperature levels, corresponding to tower condenser temperature, by minimizing the areas between the Exergy Grand Composite Curve, EGCC, and constant temperature levels of refrigeration cycles. Economic calculations were performed to obtain the lowest total annual cost, TAC, for refrigeration cycles, towers and other equipment. Two cases of the direct and indirect sequences are examined through the developed framework, inspection of their results represents that the operational cost has a significant contribution to the TAC. As a result, heat integration would reduce it by nearly 60%. Also, scrutinized analysis of the optimization results, especially by considering the TAC and its contributions, for the direct and indirect sequences, leads to the conclusion that indirect sequence would exhibit lower cost for light gas separation. The framework represented herein paves a way to the systematic design of integrated low-temperature separation processes with refrigeration cycles. [ABSTRACT FROM AUTHOR]

Heat recovery is considered as the key to improve energy efficiency in the process design. An appropriate heat exchanger network (HEN) design is an effective tool to maximize heat recovery from the process streams and to minimize energy consumption. The objectives of this study were arranging optimum HEN based on the annual cost in the power industry. HEN in the Paiton Steam Power Plant, East Java, Indonesia, was designed using spreadsheet and Aspen Energy Analyzer with Peng-Robinson equation. Pinch analysis was conducted by comparing Tmin (10°C - 19°C) to obtain Maximum Energy Recovery (MER) and Heat Exchanger Area (HEA). The HEN design was optimized using grid diagram. Simulation in this study succeeded to reduce the annual cost the most effectively at ΔTmin 16°C. This design optimized the process integration and contributed to the capital, operation, and total annual cost reduction of 14.3%. The maximum energy recovery was 286,706 kW and HEA 138.790 m². This result is a solution for Steam Power Plant as an effort for enhancing energy efficiency and the company competitiveness. [ABSTRACT FROM AUTHOR]

In view of the characteristics of the water-methyl acetate-tetrahydrofuran ternary azeotropic system, a heat integrated extractive distillation process was proposed to study its separation. The WILSON thermodynamic model was selected to calculate the vapor-liquid equilibrium data of the system, and the two-phase flash module in ASPEN PLUS software was used to simulate the relative volatility between the azeotropic components for the system under different extractant conditions. The results showed that ethylene glycol was more suitable as the extractant for the system, and the best solvent ratio was 0.37. On this basis, taking energy consumption and annual total cost (CAT) as technical and economic evaluation indicators, the conventional three-column extractive distillation process was simulated and the parameters were optimized, and the heat exchange network of the distillation system was optimized by using pinch point analysis technology. Based on the optimized results of the heat exchange network, the conventional three-column extractive distillation process was integrated with heat. The research results showed that compared with the conventional three-column extractive distillation process, the heat integrated extractive distillation process can reduce energy consumption by about 34.70%,save CAT about 21.98%,and increase thermodynamic efficiency by 36.34%.Therefore, the heat integrated extractive distillation process is a more suitable energy-saving process route for separating the ternary azeotrope system. [ABSTRACT FROM AUTHOR]

Energy integration is a critical solution for crude oil distillation units to reduce fuel consumption and environmental impacts. There are several proposed innovations for the networks of the heat exchanger, in addition to optimising operations in recent decades, for the purpose of enhancing the energy and economic efficiencies of the system of distillation of crude oil. However, retrofitting is often constrained by the constraints of maintenance, safety, and the topology of the process, but revamping managers prefer to exploit the existing equipment. Retrofit aims to reuse the existing equipment more efficiently to achieve various objectives, such as reducing utility consumption and minimising CO2 emissions. This study introduces an optimal operation modification for the purpose of enhancing the energy savings of the existing unit of crude oil distillation. First, a detailed process operation is explained, simulated, and analysed with ASPEN HYSYS software, and then two modifications are proposed. The proposed modifications aim to achieve higher energy savings while retaining the economic gain than conventional approaches and without any additional investment in a retrofit in an industrial case, especially up to 28% of the reduction of energy. It is also equivalent to a 23.38% reduction of CO2 emissions every year. [ABSTRACT FROM AUTHOR]

Trinidad and Tobago (T&T) aims to reduce the Business-As-Usual (BAU) emissions in its power generation sector by 28.7 MtCO2-e by 2030 according to its National Determined Contribution (NDC). Based on current published data, there appears to be a gap in quantifying the activity level and carbon intensity of planned actions to meet this target. Through two scenarios, this study explored the impacts of power plant dispatch optimization and new zero-carbon energy additions for T&T through adaptations of a widely used method called Carbon Emission Pinch Analysis (CEPA). A national grid emission factor (GEF) of 0.56 MtCO2-e/TWh was determined using an internationally accepted methodology from gathered power plant data. The GEF was discretized to project a BAU case to benchmark both scenarios. Scenario 1 (S1) determined T&T would achieve 8% of the NDC target if the existing supply is optimized in the years 2022 to 2030 through the compound pinch points. To achieve the target, Scenario 2 (S2) determined that at least 47% of T&T's grid energy needs to come from zero-emission carbon sources by 2022. This would equate to required capacities of 2,169 MW of solar photovoltaic or 1,549 MW of onshore wind using the most recent published capacity factors, and a decrease in the BAU GEF by 43%. [ABSTRACT FROM AUTHOR]

Ventilation heat loss is one of the most important factors contributing to energy performance of greenhouses. This paper suggests a systematic method based on dynamic pinch analysis (PA) to design an integrated heating, cooling, and ventilation system that uses ventilation waste heat in a cost-effective and energy efficient way. A heat recovery system including an air handling unit, borehole thermal storage, and a heat pump is proposed to investigate all heat integration scenarios for an entire year. In the first step, the heat integration scenarios are reduced to a few typical days using a clustering technique. Then, a generic methodology for designing a heat exchanger network (HEN) for a dynamic system, ensuring both direct and indirect heat recovery, is presented and a set of HENs are designed according to the conditions of typical days. Afterwards, the best HEN design is selected among all design alternatives using a techno-economic analysis. The whole procedure is applied to a commercial greenhouse and the best HEN configuration and required equipment sizes are calculated. It is shown that the best-performing design for the greenhouse under study produces primary energy savings of 57%, resulting in the shortest payback period of 9.5 years among all design alternatives.

The Digital Twin concept undoubtedly emerges in different industries as a must-have option for improving energy efficiency, increase maintenance reliability, prevent environmental pollution, and mitigating safety issues. However, there is still no suitable solution specifically developed for continuous monitoring and optimisation of the complex process units such as steam methane reforming (SMR) furnace used in ammonia production. The current work addresses this problem with the main goal to save energy and reduce carbon footprint. The paper investigates the application of the Digital Twin concept in combination with already proven methods for the identification and optimisation of energy-saving opportunities and reduction of CO2 emissions. The results are total energy saving between 3 and 4% with CO2 reduction of approximately 0.890 tons/h.

The Paris agreement in 2015 has required that countries commit to global carbon emission reduction by setting their national targets. In most countries, the electricity sector is identified as one of the major contributors to carbon emissions. Therefore, the governments count on decarbonizing the electricity sector to achieve their carbon reduction targets. However, this could be challenging as it is complex and involves multi-stakeholders in implementing the decarbonization plan. This work presents a mathematical optimization model to determine multi-period electricity generation planning to achieve the electricity demand and the carbon reduction target. A multi-period analysis allows long-term planning for decarbonizing the electricity sector by the gradual phasing out of coal-based power plants and the introduction of renewable-based electricity generation. To illustrate the proposed approach, the developed model is solved to strategize low-carbon energy transition planning for the Sarawak region in Malaysia. The model determines the optimal amount of new renewables required during each of the time periods, from 2020–2040, to meet the carbon reduction target. The optimal results are generated under two scenarios—no co-firing and co-firing. The generated results show that the co-firing scenario resulted in a 14.09% reduction in new renewable additions and a 5.78% reduction in the total costs. The results also determined a 66% reduction in coal consumption in 2050 when compared to the base year in 2020. [ABSTRACT FROM AUTHOR]

The ability and capability to analyze and benchmark alternative designs on top of the optimal network are deemed valuable competencies for current and future chemical engineers. In this context, a process graph (P-graph)-inspired tool – P-HENS is introduced to an integrated plant design unit in an undergraduate chemical engineering degree program at Swinburne University of Technology Sarawak Campus in Malaysia. The energy recovery aspect is one of the key design elements in the integrated plant design unit. The introduction of P-HENS, which is capable of mathematically determining multiple optimal and sub-optimal solutions is considered useful for the students to (i) identify plausible heat exchanger networks (HENs) structures that may be overlooked using conventional approaches and (ii) enable a more in-depth analysis to justify the selected design. Overall, the implementation of P-HENS shows positive outcomes, where this free-of-charge software complements the learning of conventional manual approaches used in HENs synthesis. Furthermore, recommendations suggested by the users (students) are collected and compiled for potential future software development. This work serves as an essential reference for other chemical engineering educators who are teaching pinch analysis or heat integration-related courses. [Display omitted] • Determining the n-best heat exchanger networks is challenging with manual approach. • P-HENS tool is introduced into final year project plant design unit. • Three cases are presented to show the capability of P-HENS in enhancing work quality. • Overall response from students towards P-HENS is positive evidence by the survey. • Recommendations to improve P-HENS pedagogical capability are suggested by students. [ABSTRACT FROM AUTHOR]

To improve energy efficiency and to recover energy, various mathematical models, such as pinch analysis, entropy analysis, exergy analysis, and entransy analysis, have been established to analyze heat transfer networks. In this study, these methods were applied to analyze the energy-saving effect of the epichlorohydrin unit in a certain enterprise. The results showed that when the minimum heat transfer temperature difference (ΔTmin) was 10K, 15K, and 20K, the efficiencies of the second law of thermodynamics calculated by entropy analysis were 88.02%, 93.52%, and 99.49%, respectively. The analytical method calculated an efficiency of 61.01%, 59.28%, and 57.27%, respectively, with public works' savings of 16.59%, 14.86%, and 12.02%. The pinch analysis method achieved public works' savings of 22.80%, 21.50%, and 19.35%. The entransy analysis method calculated an entransy transfer efficiency of 42.81%, 42.13%, and 41.00%, respectively, with public works' savings of 19.41%, 18.01%, and 15.70%. Based on the results, entropy analysis was found to be contrary to the principle of minimum entropy production. Exergy analysis was not able to establish a heat transfer network. The pinch analysis method was not suitable for determining the thermal efficiency of a heat transfer network as the criterion for evaluating energy saving. On the other hand, the entransy analysis method was able to establish a heat transfer network and evaluate the heat utilization of the network by entransy transfer efficiency. Overall, the data analysis was reasonable. [ABSTRACT FROM AUTHOR]

Pinch analysis is vital in optimizing heat exchanger networks (HENs). Targeting methods are used when determining cost effectiveness with pinch analysis. However, the existing targeting methods for the capital cost of HEN are not suitable for wide application scenarios. Therefore, we developed a high-accuracy general capital-cost-targeting method. It is built on a final structure that was evolved from the spaghetti structure of HEN through four loop elimination stages. This structure helps to reduce the prediction deviation of the method. To achieve high adaptability while establishing this method, we considered the different heat exchanger cost categories, different cost laws for one stream pair, and area limitations of heat exchangers that may be encountered in practice. In addition, allowing streams to use individual temperature difference contributions enhances the method's predictive capacity. The potential defects of the method found in numerical experiments and case studies were corrected with improvement measures. As a result, the accuracy and stability of the targeting method were further enhanced, with absolute target deviations generally within 10% and often within 5%. This study provides a benchmark for the optimal capital cost of HEN, allowing for a better economic effect when applying pinch analysis. [ABSTRACT FROM AUTHOR]

Most Nigerian refineries were constructed before pinch technology was developed, hence, the design were not optimal, leading to high energy loss. The objective of this work is to evaluate energy integration of crude distillation unit (CDU) of a refining and petrochemical company in Northern Nigeria using pinch analysis by utilising HINT software. Minimum heating and cooling demand of 32251.1 kW and 29637.9 kW at the pinch point of 506.5 K was evaluated from the composite curve, grand composite curve and the cascade diagram. The region of overlap in the composite curve indicates a total of 108,945 kW as the possible energy that can be recovered in the process. Existing utility demand of the unit was 96,873.5 kW, after heat integration it reduces to 61,889 kW, this showed 36.11 % energy saving with a total operating cost of US$4,560,766.5 that could be saved (annually). Minimum approach temperature (DTmin) analysis results showed an optimum DTmin of 15 K which resulted in a total annual cost of US$6,715,700. Furthermore, the analysis showed the effect of DTmin on energy, area, minimum number of units and cost targets. The design objective of the retrofit heat exchanger network (HEN) was set toward maximum energy recovery. A total of twenty (20) heat exchangers made up the new network, which comprises of twelve (12) process to process heat exchangers, two (2) heaters and six (6) coolers.