Partial Heat Integration Research Articles

Environmental evaluation and comparison of hybrid separation methods based on distillation and pervaporation for dehydration of binary alcohol mixtures with life cycle, PESTLE, and multi-criteria decision analyses

To achieve net-zero CO2 emissions by 2050, improving energy efficiency in the chemical industry is crucial. The study focuses on an environmentally friendly hybrid distillation (D)-pervaporation (PV) process to enhance energy efficiency and purity in ethanol–water and isobutanol-water mixtures, these are typical wastes in the chemical industry. Three configurations—D + PV, D + PV + D, and D + PV + D with partial Heat Integration (HI)—are evaluated for separation of ethanol–water and isobutanol-water mixtures employing the Life Cycle Assessment with Environmental Footprint (EF) V3.1 (adapted) and ReCiPe 2016 Endpoint (H) V1.08 methods, using SimaPro V9.5 software and Ecoinvent V3.9.1 database. The study also incorporates a PESTLE analysis and Multi-Criteria Decision Analysis to identify the most advantageous process for ethanol and isobutanol scenarios. The research evaluates these systems in a comprehensive manner, including technology, CO2 emissions, impacts on human health, ecosystems, resources, and Total Annual Cost (TAC). The exploration of hybrid process enhancements includes alternative renewable energy sources (i.e., solar, wind, hydro, and biofuel) and comprehensive heat integration based on Pinch Analysis using Hint V2.2 software. Results indicate that D + PV + D is the most suitable for isobutanol-water scenarios based on MCDA and Pinch analysis. In isobutanol scenarios, D + PV + D + HI reduces CO2 emissions, and human health, ecosystems, and resources impact by 15.5 %, 11.2 %, 12.6 %, and 14.6 %, respectively, with a significant 40.0 % decrease in TAC compared to D + PV. Integrating renewable energy sources further enhances its sustainability, achieving a single score of approximately one-third lower than fossil fuel consumption. Promoting renewable energy and Integrating energy flows align seamlessly with Green Chemistry and Engineering principles, representing a crucial stride towards sustainable and eco-friendly industrial practices.

Enviro-economic investigation of Novel heat-integrated configurations for pressure swing distillation

Pressure Swing Distillation is a widely adopted solution for the separation of pressure-sensitive azeotropic mixtures in various chemical industries. While this method yields high-purity products, it comes with inherent challenges such as elevated operating costs and energy consumption. However, the temperature differential between the two columns involved presents a compelling opportunity for heat integration. In this study, 18 distinct heat integration scenarios were systematically evaluated using a process simulation software to identify the optimal column configuration for minimizing the Total Annualized Cost. These scenarios span five categories: the Conventional Method, Partial Heat Integration, Full Heat Integration, Internal Heat Integration Distillation Column, and External Heat Integration Distillation Column. The Vapor Recompression Column and Divided Wall Column schemes were applied to each method. Genetic Algorithm served as the optimization tool to determine the best arrangement with TAC as the objective function. Additionally, the environmental impact, assessed through CO2 emissions, was considered. Results indicate that the most economically and environmentally friendly solution is the I-HIDiC with divided wall columns, incorporating VRC systems in both columns. This approach offers a remarkable 66.5% cost savings and a substantial 96.3% reduction in CO2 emissions.

Dynamic real-time energy saving control of pressure-swing distillation based on artificial neural networks

Parameter variation can increase economic costs and energy consumption in distillation process when disturbances occur. In this work, a dynamic optimization control model based on ANNs was developed. Composition disturbances in pressure-swing distillation with and without heat integration to separate isoamyl alcohol and toluene were regarded as the research object. The economic cost and energy consumption were effectively reduced by predicting the most optimal operating parameters during the disturbance process and controlling the process in real time. In the absence of heat integration, the energy consumption of the control structure based on ANNs (CS2) is reduced by 1.68% and 1.70% respectively compared to traditional control structure (CS1) during ± 20% composition disturbance. In partial heat integration, the energy consumption of the control structure based on ANNs (CS4) is reduced by 3.24% and 2.68% compared to traditional control structure (CS3). TAC is saved by 3.51% and 3.31% when reaching stability.

Economic and entropy production evaluation of extractive distillation and solvent-assisted pressure-swing distillation by multi-objective optimization

Extractive distillation (ED) and solvent-assisted pressure-swing distillation (SA-PSD) are both special distillation processes that perform good at separating pressure-insensitive azeotropes. However, few reported studies have compared the performance of the two processes. In this paper, ED processes with N-methylpyrrolidone (NMP) and dimethlac-etamide (DMCA) as entrainer, SA-PSD process with isopropyl-alcohol (IPA) as solvent and SA-PSD process with partial heat integration (PHI-PSD) are proposed to achieve high purity separation of a mixture of cyclohexane/2-butanol system. The optimal operating conditions of the processes are obtained after optimizing with NSGA-II algorithm when total annual cost (TAC) and the entropy production of process are set as objectives. The optimal results show that the optimal PHI-PSD process has lower TAC by 28.7% and the lower entropy production by 39.5% than the optimal SA-PSD process while the ED process with NMP as entrainer has lower TAC by 50.9% and the lower entropy production by 56.1% than the optimal SA-PSD process. The optimal results show that the ED process with NMP as entrainer has the best economic and thermodynamic efficiency among the four proposed processes in this paper.

Atmospheric-Pressurized Process for Dimethyl Carbonate/Methanol Separation with and without Heat Integration: Design and Control.

Process economy and dynamic controllability are critical for DMC/MeOH separation via the PSD process. In this paper, rigorous steady-state and dynamic simulations of atmospheric-pressurized process for DMC/MeOH separation with no, partial, and full heat integration have been carried out with Aspen Plus and Aspen Dynamics. Further investigations have been conducted into the economic design and dynamic controllability of the three neat systems. Simulation results indicated that: the separation process via full and partial heat integration provided TAC savings of 39.2 and 36.2%, respectively, compared to that of no heat integration; the non-heat-integrated system displays good dynamic performance, critical dynamic penalties were demonstrated for both partial and full heat integration processes, while the partial one exhibited a more robust control except for precisely maintaining XB2(DMC); a PCTC scheme with a CC/TC cascade control was proposed to precisely maintain the product concentration for the fully heat-integrated PSD process. A comparison of the economy between atmospheric-pressurized and pressurized-atmospheric sequences indicated that the former is more energy efficient. Further, a comparison of the economy between atmospheric-pressurized and pressurized-atmospheric sequences indicated that the former is more energy efficient. This study will provide new insights into the energy efficiency and has some implications for design and control of DMC/MeOH separation in the industrialization process.

Economic optimization and dynamic control of pressure‐swing distillation for separating the ternary azeotrope of butanone/n‐heptane/isopropanol

AbstractBACKGROUNDEconomic optimization and dynamic control of the separation process for recovering the ternary mixture of butanone (MEK)/n‐heptane/isopropanol (IPA) from industrial wastewater is a significant topic. In this work, the optimal pressure‐swing distillation (PSD) sequence, heat integration and dynamic control for separating MEK/n‐heptane/IPA were investigated systematically. The optimal separation sequence was determined by combining the minimum total annual cost (TAC) with the residual curves map (RCM). Pressure‐swing distillation with non‐heat integration, partial heat integration or full heat integration was compared in terms of TAC. Dynamic control schemes were designed for optimal processes of two separation sequences with and without heat integration.RESULTSThe results demonstrate that the TAC of optimal PSD with non‐heat integration process can be reduced by 31.11%, whereas the TAC of optimal partial heat integration and full heat integration schemes can be reduced by 39.73% and 40.96%, respectively. The dynamic performance of all control schemes that can resist ±20% feed flow disturbances and composition disturbances are compared with the integral of squared error.CONCLUSIONIt is demonstrated that PSD with full integration process (FHIPSD) for separating MEK/n‐heptane/IPA has optimal economic performance, whereas PSD with non‐heat integration process (NTIPSD) has the optimal dynamic performance and robust stability. This work provides a significant reference for industrial separation of MEK/n‐heptane/IPA. © 2022 Society of Chemical Industry (SCI).

Configuration optimization of a multi-generation plant based on biomass gasification

Heat integration and configuration optimization of a unique cycle based on biomass gasification are presented. The system provides heat, freshwater, and electricity to an area located in the southern part of Iran using the gasification of sugarcane bagasse. The main question to be responded is to find the optimum configuration which minimizes the total external utility consumption. It is assumed that 34500 kg/day of bagasse is available and the electricity, heating, and water demand of the area should be covered. It is concluded that the total utility consumption is 3113.69 kW if no heat integration is utilized. On the other hand, partial heat integration results in a total utility consumption of 590.93 kW. The least possible utility consumption which occurs in full heat integration condition is 214.6 kW. By increasing the gasification temperature from 900 °C to 915 °C, it is possible to enhance the integration by removing one of the heaters. The sensitivity analysis shows that the highest CHP efficiency occurs for a biomass flow rate of 32970 kg/day. It is concluded that energy integration techniques serve well in the identification of the optimum gasification temperature and biomass flow rate which lead to the minimum utility consumption and highest CHP efficiency.

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Abstract Dynamic controls of pressure-swing distillation with an intermediate connection (PSDIC) process of ethyl acetate and ethanol separation were investigated. The double temperature/composition cascade control structure can perfectly implement effective control when ± 20% feed disturbances were introduced. This control structure did not require the control of the flowrate of the side stream. The dynamic controllability of PSDIC with partial heat integration (PHIPSDIC) was also explored. The improved control structure can effectively control ± 20% feed disturbances. However, in industrial production, simple controller, sensitive and easy to operate, is the optimal target. To avoid the use of component controllers or complex control structure, the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased, albeit by incurring a slight rise in the total annual cost (TAC). This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.

Design and comprehensive analysis of a novel pressure-swing batch distillation process for the separation of a binary azeotrope with various boiling behaviors

Batch distillation is widely employed in the fine chemical industry because of its operational flexibility. The mixture of n-heptane and isobutanol exhibits a special azeotropic phenomenon by which it changes from a minimum-boiling azeotrope to a maximum-boiling one with increasing pressure. However, the traditional double column batch rectifier and double column batch stripper processes cannot separate the mixture efficiently. Therefore, the double-column batch stripper–rectifier (DCBS-R) process was designed to obtain high-purity products, based on the azeotropic phenomenon. Further, control structures are explored to achieve stability, and the final purities of the separated products are over 99.9%. Each batch of raw materials is 100 kmol, and the expected annual production capacity is 800 batches. Additionally, a precooler of the low-pressure column (LPC) is introduced to reduce the exergy destruction by exergy analysis. The equipment cost and CO2 emissions are analyzed afterward to optimize the process, based on the multi-objective optimization method. Further, the number of stages and the pressure of the columns are optimized. The optimal obtained total annual cost (TAC) and CO2 emissions of the DCBS-R process are 2.26 × 105 $/y and 4.92 × 105 kg/y, respectively. The partial heat integration is studied to further improve the process performance, thus obtaining TAC and CO2 emissions of 2.22 × 105 $/y and 3.80 × 105 kg/y, which are 7.1% and 22.76% lower than the values obtained from the optimal process, respectively.

The process control of the triple-column pressure-swing extractive distillation with partial heat integration

Recently, increasing researches have focused on the intensified heat-integrated triple-column pressure-swing extractive distillation (HITPED) owing to its superiority in economic and environmental benefits than the conventional extractive distillation. However, the dynamic controllability investigation for HITPED was lacking, resulting in the difficulties for industrial application. Therefore, separating the ternary azeotropic mixture tetrahydrofuran (THF)-methanol-water by HITPED is taken as an example to fully investigate the dynamic controllability. On the basis of the open-loop analysis a basic control structure CS1 is firstly proposed. To deal with the 20% disturbance in feed composition more effectively, the CS2 with a low selector and composition controllers is then developed. Nevertheless, composition controllers are less applied in chemical industry than temperature controllers owing to the long delay and high cost. As such, two different control structures (CS3 and CS4) without any composition controllers are then put forward. Integral absolute error (IAE) is applied to compare the dynamic performance. Under the 20% disturbances of the feed flowrate and composition, the robust control strategy CS4 with temperature controllers and a high selector exhibits the gratifying dynamic performance. The application of the selector further enlarges the dynamic researches in the distillation process.

Control of a pressure-swing distillation process for benzene/isopropanol/water separation with and without heat integration

Controlling the behavior of processes for the recovery of benzene and isopropanol from industrial wastewater is an important topic. In this work, dynamic control structures are investigated for the separation of azeotropic water, benzene, and isopropanol mixtures using triple column pressure-swing distillation (without heat integration, with partial heat integration, and with full heat integration). Composition and flow disturbances are utilized to examine the performance of the control structure, and four improved control structures are developed and show good control effects. The ratio of reboiler duty to mole feed flow rate control structure showed good control behavior in face of the disturbances for the ternary pressure swing distillation processes. The integral of squared error (ISE) values of the control structure was combined with the dynamic response curves to compare the performance of the control structures. The ISE value of the improved control structure with full heat integration was smaller than that of the improved control structure without heat integration and the improved control structure with partial heat integration. The total annual cost (TAC) of the full heat integration process was also lower than the values for the other three processes. Based on its control performance and TAC, the improved control structure with full heat integration was concluded to be the best of the control structures. This work can serve as a reference for industrial development.

Pressure swing distillation for the separation of methyl acetate‐methanol azeotrope

AbstractPressure swing distillation (PSD) process was used to separate methyl acetate‐methanol azeotrope. Through the phase diagram analysis, distillation sequence and technological process were determined. On the basis of the principle of the minimum total annual cost (TAC), design variables such as feeding position, reflux ratio, and column plate number were optimized and the optimal parameters were determined. The high‐pressure column (HPC) under various pressures were analysed. The economic results of the PSD without heat integration, with partial heat integration, and with full heat integration were compared. The comparison results indicate that the TAC of the PSD without heat integration is the highest. The PSD with partial integration and full heat integration can effectively reduce the total capital cost and total operating cost. Compared with the PSD without heat integration, the TACs of partial heat integration and full heat integration exhibit 27% and 30% savings, respectively. Therefore, the PSD with full heat integration is more economically reasonable for separating methyl acetate‐methanol azeotrope.

Separation of a ternary mixture with multiple azeotropes via pressure‐swing distillation

AbstractBACKGROUNDThe ternary mixture of tetrahydrofuran (THF), ethanol and water contains multiple azeotropes with the sensitivity to pressure variation. The pressure‐swing distillation (PSD) is a promising method to achieve the system's separation objective since it avoids many potential problems caused by adding a third component.RESULTA variety of separation sequences were synthesized on the ternary diagram, including the sequences of WLEMTH, WLTH EM, THEMWL, THWLEM, EMTHWL and EMWLTH. The optimal design parameters of these sequences were obtained based on the minimum total annual cost (TAC) by using the sequential iterative global optimization algorithm. Furthermore, six kinds of heat integration that improve energy efficiency were implemented for the optimal alternative of EMTHWL.CONCLUSIONThe results show that the EMTHWL configuration has the lowest TAC, saving 37.84% of the economic cost compared to the THEMWL which has the highest TAC. The partial heat integration among three columns can achieve almost the same reductions in energy requirements and carbon dioxide emissions (44.9%) as the full heat integration among three columns (45.4%). In addition, it is predictable that the partially heat‐integrated alternative compared to other fully heat‐integrated schemes has less undesirable side effects in the aspect of dynamic control. © 2019 Society of Chemical Industry

Exploration of a heat-integrated pressure-swing distillation process with a varied-diameter column for binary azeotrope separation

The pressure-swing distillation (PSD) processes with varied-diameter columns (VDCs) for separating methanol–chloroform and n-heptane–isobutanol are studied. Furthermore, two heat-integrated PSD processes, partial integration and full heat integration, are discussed with ordinary and VDCs. The results show that whether it is heat integrated or non-heat integrated, the processes using VDC have an advantage in the economy. Based on the minimum total annual cost (TAC), the dynamic controllability without and with full heat integration for an azeotrope system methanol/chloroform is explored. The dynamic controllability without and with partial heat integration for the azeotrope system n-heptane/isobutanol is discussed. The results indicated that compared with the dynamic responses without heat integration process, the heat-integrated PSD with a VDC did not increase the control difficulty while maintaining its economy. More azeotropic systems should be studied to investigate their economics and control effects, which will benefit PSD design and industrial application.

Comparison of pressure-swing distillation and heterogeneous azeotropic distillation for recovering benzene and isopropanol from wastewater

Two methods of pressure-swing distillation (PSD) and heterogeneous azeotropic distillation (HAD) are investigated to recover benzene and isopropanol from wastewater. This ternary mixture can form two homogenous azeotropes (binary) and two heterogeneous azeotropes (binary and ternary), which all are sensitive to pressure. The proposed configurations are rigorously simulated and optimized based on the minimum total annual cost (TAC) via the sequential iterative procedure, and meanwhile the partial heat integration is taken into account respectively. The results show that both configurations of PSD are superior to the HAD configuration combining with PSD from the perspectives of economic and energy.

Comparison of extractive distillation separation sequences for acetonitrile/methanol/benzene multi‐azeotropic mixtures

AbstractBackgroundThe extractive distillation‐based separation of a multi‐azeotropic mixture has several optional solvents and schemes. The screen of a suitable solvent was performed and diverse extractive distillation sequences were compared for separating the specified mixture of acetonitrile/methanol/benzene.ResultAs a solvent breaking all binary azeotropes, chlorobenzene was selected over aniline on the basis vapor–liquid equilibrium diagrams and infinite dilution factors. Four separation sequences were optimized by the sequential iterative procedure on the basis of minimal total annual cost (TAC), and CO2 emissions were calculated. Among four sequences, sequence III, composed of two extractive distillation columns and one solvent recovery column, is the best scheme from environmental and economic viewpoints. Simple partial heat integration was further implemented and can save 20.08% and 8.86% in terms of energy cost and TAC.ConclusionThe results demonstrate that the separation of acetonitrile/methanol/benzene is fully achievable using common extractive distillation with chlorobenzene as solvent. Moreover, there is a trade‐off between heat transfer in the reboiler‐condenser and corresponding energy consumption variations due to pressure changes when considering heat integration. © 2018 Society of Chemical Industry

Comparative analysis of extractive and pressure swing distillation for separation of THF-water separation

In the present work, extractive and pressure-swing distillation methods are analyzed in detail through steady state ASPEN Plus simulations to propose the most economic method for separation of equimolar mixture of THF-Water. Various solvents were evaluated and DMSO was identified as the most appropriate solvent, as it gave minimum Total Annual Cost (TAC) for desired purity. In case of pressure swing distillation, various pressure ranges were explored to achieve minimum TAC. Configurations for extractive and pressure swing distillation with heat integration were also worked out. The optimum designs of extractive and pressure swing distillation with and without heat integration were compared on a common basis of feed conditions and purity constraints. Results indicate that TAC of extractive distillation with heat integration is 5.2% less than that of PSD with partial heat integration.

Heat Integration and Control of a Triple-Column Pressure-Swing Distillation Process

Heat integration and dynamic characteristics are critical for the triple-column pressure-swing distillation (TCPSD) processes that are used to separate ternary or multicomponent systems. In this study, rigorous steady-state simulations of heat-integrated TCPSD processes are optimized using Aspen Plus, and dynamic strategies for the different TCPSD processes are explored using Aspen Dynamics. When ±20% feed flow rates and composition disturbances are introduced, the composition/temperature cascade control structure (CSB), which uses stage 19 as the temperature-sensitive stage in the second column, exhibits better controllability than the CSA, which uses stage 4 as the temperature-sensitive stage. Three cases of partial heat integration are studied, and the first case, which uses an auxiliary condenser, is the most economic. The dynamic control strategies of the first and second cases handle ±10% feed disturbances well; however, the CSE can attain good controllability when ±20% feed disturbances are introdu...

Separation of an azeotropic mixture of dimethyl carbonate and methanol via partial heat integration pressure swing distillation

AbstractA method for dimethyl carbonate and methanol separation using pressure swing distillation is presented, and the optimum design is proposed by minimizing the total annual cost as the objective function. It is revealed that compared with no heat integration pressure swing distillation (HIPSD), partial HIPSD reduces the total annual cost by 20.01%. This paper presents a criterion for selection of the temperature control stage in the low‐pressure column (LPC), the temperature profile of which is quite close to linear. Additionally, the influences of the temperature stage in the LPC on the dynamic responses in the partial HIPSD are investigated. The results show that the composition/temperature cascade control structure with stage 10 or 31 selected as the control stage in the LPC can achieve efficient controllability of the process, even for large feed flow rates and composition disturbances. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Design and control of methyl acetate-methanol separation via heat-integrated pressure-swing distillation

Design and control of pressure-swing distillation (PSD) with different heat integration modes for the separation of methyl acetate/methanol azeotrope are explored using Aspen Plus and Aspen Dynamics. First, an optimum steady-state separation configuration conditions are obtained via taking the total annual cost (TAC) or total reboiler heat duty as the objective functions. The results show that about 27.68% and 25.40% saving in TAC can be achieved by the PSD with full and partial heat integration compared to PSD without heat integration. Second, temperature control tray locations are obtained according to the sensitivity criterion and singular value decomposition (SVD) analysis and the single-end control structure is effective based on the feed composition sensitivity analysis. Finally, the comparison of dynamic controllability is made among various control structures for PSD with partial and full heat integration. It is shown that both control structures of composition/temperature cascade and pressure-compensated temperature have a good dynamic response performance for PSD with heat integration facing feed flowrate and composition disturbances. However, PSD with full heat integration performs the poor controllability despite of a little bit of economy.