Reactive Dividing Wall Column Research Articles

Study on a New Reactive Dividing-Wall Column for the Reaction of Vinyl Carbonate and Methanol Ester Exchange to Produce Dimethyl Carbonate

Study on a New Reactive Dividing-Wall Column for the Reaction of Vinyl Carbonate and Methanol Ester Exchange to Produce Dimethyl Carbonate

Novel side-reactor dividing wall column and reactive distillation process for enhanced electronic-grade propylene glycol monomethyl ether acetate production

The semiconductor industry is experiencing rapid growth and has become one of the largest sectors in the world. Propylene glycol monomethyl ether acetate (PGMEA) is prized for its exceptional properties and its ability to meet the stringent requirements as a solvent for electronic processing. This work aims to enhance the production of electronic-grade PGMEA through a practical and advanced intensified configuration. First, the kinetic reactor for propylene glycol monomethyl ether (PGME) synthesis has been modeled and pinpointed optimal operating conditions through sensitivity analysis. Subsequently, several process alternatives incorporating intensified techniques, such as the dividing wall column (DWC), pressure swing distillation (PSD), reactive DWC (RDWC), and side-reactor DWC (SR-DWC), have been investigated. These processes have been systematically designed and optimized through a sequential design procedure. Response surface methodology, a practical optimization method, has been employed to optimize the complex column's structure with the help of Aspen Plus and Minitab. Energy requirements and costs of all process alternatives were evaluated for a fair comparison. The SR-DWC-RD process has emerged as the most promising option, as it can save up to 11.5 % in energy requirements and 19.9 % in total annual costs. This practical design, complete with detailed optimal design parameters, presents significant opportunities for improving industrial PGMEA production.

Adaptable heat pump-assisted dividing-wall column design for intensified downstream processing of bio-propionic acid

Propionic acid is a valuable platform chemical that is usually produced via fossil routes. As these are energy-intensive and eco-unfriendly processes, fermentative production of propionic acid is becoming more attractive. However, the complex downstream processing (due to low achievable product concentrations, high water content, presence of by-products and thermodynamic constraints), presents a potential barrier to scale-up this technology. This original research proposes a novel intensified large-scale (production capacity of ∼ 20 ktonne/y) process for the final recovery of propionic acid after the initial biomass and counterion removal. Vacuum distillation steps ensure the recovery of a high-purity succinic acid product (>99.9 wt%) and a water stream that may be recycled to the fermentation to reduce the fresh water requirements. The main unit that follows is a highly integrated heat pump-assisted dividing-wall column (DWC), which allows the effective separation of propionic (>99.9 wt%) and acetic acid (99.4 wt%) products. Alternatively, it can serve as a reactive DWC that performs the esterification and separation of methyl propionate (99.8 wt%), methyl acetate (91.0 wt%) as higher added value products, and water by-product. If needed, extractive distillation can be implemented additionally to recover methyl acetate at higher purity (99.9 wt%). Overall, both options are proven to be economically interesting (recovery costs of 0.399 – 0.469 $/kg considering the product price of 1.349 – 1.802 $/kg) and environmentally attractive (3.206 – 3.678 kWthh/kg).

Design of intensified chemical processes for the production of ethyl tert-butyl ether

Process intensification contributes to the design of processes with better sustainability performance by allowing several tasks to be performed within the same equipment unit, for instance, reaction and separation. This work aims at the design of intensified processes using a phenomena-based methodology. A gradual intensification approach is used, and each structure is evaluated from economic and environmental considerations. A production process of ethyl tert-butyl ether (ETBE) was selected as a base flowsheet to be intensified. The process consists of one reactor and three conventional distillation columns. Three intensified process alternatives are developed, which employ technologies such as reactive distillation column (RDC), dividing wall column (DWC), and reactive dividing wall column (RDWC). The fully intensified structure, based on a RDWC, showed the best economic indicator with a total annual cost reduction of 26.7% with respect to the base case process; the partially intensified structures showed similar improvements of 18%. The energy savings offered by the intensified flowsheets provide direct benefits from environmental considerations.

Multi Objective Optimization using Non-Dominated Sort Genetic Algorithm with Artificial Neural Network for Reactive Dividing Wall Column

Multi Objective Optimization using Non-Dominated Sort Genetic Algorithm with Artificial Neural Network for Reactive Dividing Wall Column

Optimal design, intelligent fuzzy logic and model predictive control for high-purity ethyl-methyl carbonate and diethyl carbonate production using reactive dividing wall column

Methyl carbonate (EMC) and Diethyl carbonate (DEC), as excellent solvents for lithium-ion electrolytes, are synthesized by transesterification, and consecutive reaction seriously complicate optimization and control issues. Process synthesis, parameters optimization and advanced control are crucial points that should be addressed for this ill-conditioned and highly nonlinear system, which is the motivation and novelty of present work. With single-objective and multi-objective genetic algorithm, intensified processes for EMC and DEC production were optimized respectively with heterogeneous catalyst. And reactive dividing wall column achieved 23% and 13% total annualized cost reductions compared with reactive distillation for two target carbonates. Based on optimal steady-state solution, intelligent fuzzy logic and model predictive control of EMC and DEC production is conducted to clarify their respective strengths in intensified process with consecutive reaction. Sequential optimization for parameters of FLC was carried out with Integral of Squared Error (ISE) as objective. Finally, control performance of FLC and LPMC are compared with that under PID control, and results show that overshoot and transition time under FLC and LMPC are obviously mitigated, along with evident reduction in ISE.

Co-process intensification in the synthesis and design of reactive double dividing-wall distillation columns

In most cases, the reactive single dividing-wall distillation column (R-SDWDC) and its corresponding conventional reactive distillation system (CRDS) fail to yield the best performance in the separations of reacting mixtures with unfavorable reaction kinetics and/or unfavorable thermodynamics properties. In this work, a novel methodology of co-process intensification is proposed for the synthesis and design of reactive dividing-wall distillation columns. The methodology leads to the establishment of a reactive double dividing-wall distillation column (R-DDWDC), and the included intermediate separating section plays a vital role in coordinating these two kinds of process intensification and consequently guarantees its optimum performance. In terms of two example systems involving the separations of the ideal quaternary reversible reaction with a somewhat unfavorable ranking of relative volatilities (A + B ↔ C + D with αA > αC > αB > αD) and the transesterification of methyl acetate with n-propanol, the proposed methodology is evaluated. The R-DDWDC is found to yield much better performance than the CRDS and R-SDWDC in the separations of the reacting mixtures with somewhat unfavorable ranking of relative volatilities, and such outcomes definitely corroborate the effectiveness and advantages of the proposed methodology for process development. Although the proposed methodology is developed solely based on the separations of the reacting mixtures with somewhat unfavorable ranking of relative volatilities, it is of great implication to the separations of the other reacting mixtures with unfavorable reaction kinetics and/or unfavorable thermodynamics properties.

Parallel column model for reactive dividing wall column simulation

Reactive Dividing Wall Column (RDWC) modelling has attracted significant attention in recent years because simulations of processes containing such columns have demonstrated the potential for significant savings in energy and capital cost. Most modelling of these columns involves decomposing RDWCs into a thermodynamically equivalent flowsheet of reactive and non-reactive column sections in a sequential modular process simulation package. Such simulations of (R)DWCs can be time consuming to create and difficult to converge. It has been suggested that equation-oriented solvers can have superior numerical performance. Here, we use a CAPE-OPEN compliant equation-based parallel column model (PCM) that enables the rapid modelling of an RDWC as a single self-contained unit. Some conventionally modelled RDWCs from the literature are reproduced with the PCM to demonstrate its validity and excellent numerical performance. The ease and rapidity with which different RDWC configurations can be created is a significant advantage of our PCM.

Development of an industrial reactive dividing wall column process through laboratory-scale experimentation and modeling

Reactive dividing wall columns (RDWCs) are highly integrated distillation systems that simultaneously carry out chemical reactions and multicomponent separations within the same vessel. Reactive distillation columns (RDCs) are well established and dividing wall columns are becoming increasingly popular in chemical processes due to their ability to present significant capital and operating costs savings. However, RDWCs have not been commercially adopted, in part, due to the lack of experimental studies and validated models. Therefore, this work studied the aldol condensation of propionaldehyde using a laboratory-scale RDWC to increase knowledge in this area.This work focused on designing, building, and testing a laboratory-scale RDWC to demonstrate its ability to maintain steady-state and meet process objectives. Additionally, a model was create and compared against the experimental data for validation. By using the tools of modeling and experimentation to explore the aldol condensation test system from kinetics and phase equilibria experiments to RDC then RDWC experimentation, this work creates a roadmap for evaluating the commercial potential of a RDWC system. Additionally, this work validated the approach of using scaleable Oldershaw laboratory distillation glassware to investigate a RDWC and for model validation.

Design of Reaction Region of Reactive Dividing Wall Column Based on Cross-Wall Heat Transfer

The reactive dividing wall column (RDWC) is a column structure that couples a reactive distillation and dividing wall column. It has become a research hotspot because of its remarkable advantages in energy consumption. Most RDWCs ignore the possibility of cross-wall heat transfer. For the RDWC, the effect of reaction heat is also ignored. In this work, the reaction of methyl acetate with butanol was studied, and Aspen is used to study the effect of the reaction heat and reaction region length on the cross-wall heat transfer. The results show that compared with the RDWC with an adiabatic cross-wall, the RDWC with cross-wall heat transfer can save 3.2% energy. Cross-wall heat transfer could achieve reactants conversion of 99.4%. From the perspective of energy saving maximization, the double reaction region is set. The research results show that the RDWC with cross-wall heat transfer in the double reaction region can save 4.2% energy compared with the cross-wall insulation.

Simulation, optimization and intensification of the process for co-production of ethyl acetate and amyl acetate by reactive distillation

A new energy-saving process is proposed here for the co-production of ethyl acetate (EtAC) and amyl acetate (AmAC) by reactive distillation(RD). The thermodynamic feasibility of the ethyl acetate/amyl acetate system was determined based on its physical properties. As amyl acetate has a higher water-carrying capacity than ethyl acetate, water can be removed from the reaction system in the form of azeotrope to improve the conversion rate, and amyl acetate can be easily separated from the water. The reactive distillation process of ethyl acetate-amal acetate co-production with different alcohol feed ratios was studied in this paper. When the amyl alcohol to ethanol feed mole ratio was set at 2, the process performed better in terms of economy and energy consumption; it also had a less environmental impact at the same time. The reactive distillation process with intermediate condenser and intermediate reboiler (RD-IC-IR) process and the reactive dividing-wall column (RDWC) process are established based on process optimization. Compared with the RD process, the TAC and CO2 emissions for the RD-IC-IR process reduced by 21.92 % and 28.27 %, respectively, and the thermodynamic efficiency improved 38.86 %; the TAC and CO2 emissions for the RDWC process reduced by 36.11 % and 42.49 %, respectively, and the thermodynamic efficiency improved 74.45 %.

A multi-scale and multi-objective optimization strategy for catalytic distillation process

This work aims to establishing a multi-scale and multi-objective optimization strategy for the catalytic distillation process. Firstly, the catalyst layer efficiency factor correlation that embraces the influence of the catalyst layer structure was obtained and then coupled with the process simulation to establish a multi-scale model for the catalytic distillation process. On this basis, genetic algorithm was employed to realize the multi-objective optimization. The hydrolysis process of methyl acetate in the reactive dividing wall column was investigated. The equipment parameters and operational conditions of the catalytic distillation column, and the structure parameters of the catalyst layer are optimized simultaneously. The results indicated that the minima of the total annual cost, the gas emission cost and the exergy loss decrease by 19.26%, 23.11% and 67.27%, respectively, by comparing with the counterparts obtained from the single-factor sensitivity analysis. Furthermore, the catalyst cost decreases by 30.88% per year.

Production of ethyl lactate by reactive dividing wall column using analysis of the statics

The sustainable development in separation-reaction processes involves a higher energy efficiency and pollutant reduction. The main interest of the analysis of the statics methodology is developed the optimal qualitative technological scheme with minimal data, the physicochemical information of the system, and the stoichiometry of the reaction. This results in a feasible intensified scheme flowsheet and a reactive distillation column (RD) that are then implemented in a reactive dividing wall column (RDWC) distillation to produce ethyl lactate from the esterification of lactic acid with ethanol. The RDWC configuration showed a reduction of 38% in the save net duty and an increase of 13% in the conversion compared with a conventional direct sequence. The analysis of the statics method presents an alternative in the design stage in a complex column, allowing for a feasible operation in different degrees of process intensification.

Optimization and model-based control of sustainable ethyl-methyl carbonate and diethyl carbonate synthesis through reactive distillation

As excellent solvents of lithum-ion electrolyte, ethyl-methyl carbonate (EMC) and diethyl carbonate (DEC) are synthesized through transesterification of dimethly carbonate (DMC) and ethanol. Process intensification, optimization and the corresponding control scheme of the synthesized process are essential when sustainability is becoming a necessity. In the present work, the intensified flowsheet for EMC and DEC production process was firstly proposed and optimized with conventional reactive distillation (RD) and reactive dividing wall column (RDWC), respectively. Compared with RD process, RDWC could achieve 25.3% and 8.2% total annualized cost reduction for EMC and DEC production process, respectively. And carbon dioxide emission could be decreased by 29.4% and 11.7% by further integrating RD and separation column into RDWC arrangement for DEC and EMC production. Then multi-loop PI control schemes were developed as benchmark and linear model predictive controller was designed to handle the persistent feed disturbance. The superiorities of model-based controllers for the strongly interactive and coupled system are demonstrated by the dynamic response comparisons in terms of settling time, overshoot and integral of squared error (ISE), especially for the controlled variables with poor control performance under conventional multi-loop PI control structure. To summarize, the comprehensive control performance index-ISE with MPC is reduced by 55.9%–99.1%, as compared to those under PI control strategy.

Evaluation of the Aldol Condensation of Propionaldehyde as a Reactive Dividing Wall Column Test System

Evaluation of the Aldol Condensation of Propionaldehyde as a Reactive Dividing Wall Column Test System

Demonstration of applied linear model predictive control for an enzymatic reactive dividing wall column

The synergistic integration of different processing steps in multifunctional units offers huge potential for bioprocess intensification. Especially reactive separation technologies have been widely applied in chemical processes, with reactive distillation being termed the front-runner of industrial process intensification. The concept can be transferred to bioprocesses in terms of enzymatic reactive distillation, which can further be intensified through thermal coupling with a subsequent distillation column into an enzymatic reactive dividing wall column. While such a highly integrated process offers considerable potential for operational and investment cost savings, it also faces operational challenges and limitations caused by the strong degree of integration and the temperature sensitivity of the biocatalyst, that need to be addressed by a sophisticated process control system. The current study demonstrates the applicability and efficiency of a linear model predictive control approach for the enzymatic reactive dividing wall column in a pilot plant application. The transesterification of butanol and hexyl acetate to hexanol and butyl acetate, catalyzed by the enzyme CalB (Novozym 435), serves as a model reaction. The control performance is illustrated for a setpoint adjustment and a feed disturbance, for which a comparative evaluation with an established PI-control approach is conducted.

Evaluation on the solketal production processes: Rigorous design, optimization, environmental analysis, and control

This works aims at evaluating different process configurations for producing solketal from reacting glycerol with acetone. The research carries out the regression of thermodynamic and kinetic parameters, rigorous design of four process configurations, optimization, carbon emission analysis, and control. The results from steady-state analysis reveal that the solvent-free coupled reaction/distillation (SFCRD) process is the most promising. It reduces 40.09% of total annual cost and 45.09% of CO2 emission from the base case, the separated reactor-distillation process. Besides, the CO2 emission rate of the SFCRD process is found 35.29% and 65.91% less than the recently reported upper and the middle partition reactive dividing-wall column process, respectively, indicating the unfavorability of intensifying this reacting system through reactive distillation. Finally, a control structure for the SFCRD process is established for effectively handling the disturbances from the flowrate, composition and catalyst deactivation. Through the dynamic simulation, the closed-loop control results were revealed satisfactory.

Experimental Investigation, Process Design, and Optimization Analysis on the Production of Solketal in the Reactive Dividing Wall Column

This paper aims at intensifying the synthesis process of solketal by the reactive dividing wall column (RDWC) through experiments and simulation optimization and proposes a high-efficiency producti...

Conceptual design of a dual reactive dividing wall column for downstream processing of lactic acid

Methodologies for designing intensified processing units are necessary to enable the industrial application of process intensification concepts. This article presents a ruled-based systematic methodology for the synthesis and conceptual design of a dual reactive dividing wall column (dual R-DWC). A decomposition approach is used to identify the tasks required for the separation by introducing a reactive separating agent to exploit a reversible reaction to enhance the driving forces. A combination of shortcut and rigorous simulations led to the conceptual design of a novel dual R-DWC in which the forward and reverse reactions and the separation occur at once.The methodology was demonstrated in a case study for the separation of lactic acid from dilute aqueous streams and a reactive impurity that hinders the lactic acid conversion and its recovery, while the byproducts may bring new challenges for the desired separations.This study is the first to investigate the effect of reactive impurities on the reaction and the separation, hence adding a more realistic framework to the design. The flowsheet produced was evaluated against benchmark processes and showed a significant process improvement in terms of energy savings (ranging 13-27 %), material intensity (28-32 % reduction), and water consumption (22-36 % reduction), while the reactive impurities are effectively removed.

The hybrid RDWC–pervaporation with series–parallel arrangement and heat integration for ETBE production

A new process configuration consisting of hybrid reactive dividing wall column (RWDC)–pervaporation (PV) (with series–parallel arrangement) with feed splitting and heat integration was proposed to produce ETBE. To evaluate the performance of the proposed method, it should be compared with other ETBE production processes. A total of 12 ETBE production processes were optimized for this purpose. All process parameters were considered optimization variables. TAC was used as objective function, but all processes were also compared in terms of energy consumption. To reduce the energy cost in the PV process, heat integration between the internal RDWC flows and streams entering the PV modules was used to eliminate all heaters in the PV process and also the RDWC condenser. Feed splitting was used to reduce the heat duty of the RDWC reboiler. According to the results, the proposed method reduced the TAC by 59% and 36% respectively compared with the conventional processes and the RDWC. This TAC reduction in the hybrid RDWC–PV process relative to the RDWC can be related to a decrease in the number of trays in the main and prefractionator sections, elimination of the condenser and a significant reduction in the heat duty of the reboiler.