Process Intensification for Chemical Engineering and Processing

A special issue of ChemEngineering (ISSN 2305-7084).

Deadline for manuscript submissions: 30 December 2024 | Viewed by 21391

Special Issue Editors

Institute of Chemical Engineering, Laboratory of Thermal Process Engineering, Ulm University, 89081 Ulm, Germany
Interests: process intensification; (multiple) dividing wall columns; additive manufacturing; process simulation; process optimization; process thermodynamics
Special Issues, Collections and Topics in MDPI journals
Department of Lifes Sciences and Engineering, TH Bingen - University of Applied Sciences, 55411 Bingen am Rhein, Germany
Interests: chemical reaction engineering; process intensification; extraction centrifuges; process optimization methods; hydrogen production; fuel cells

Special Issue Information

Dear Colleagues,

Although more than 20 years have passed since our colleagues Stankiewicz and Moulijn defined process intensification in all its variations, much research work is still taking place in this field. On the level of unit operations and their combinations or on the process level, the methods have found wide applications in the process industry, but a thorough and theoretical understanding that would enable us to predict critical effects is still lacking. At the same time, intensified processes are becoming increasingly important. Efficient processes are the indispensable prerequisite for coping with the challenges of the future. They help to make the chemical industry more sustainable in terms of resource consumption and pollutant emissions. Simultaneously, they allow the chemical industry, especially in high-wage countries, to maintain its competitiveness. As we see the great potential of bringing research and applications together in order to optimize existing processes or to improve process development strategies, we would be grateful if you would consider publishing in this Special Issue of ChemEngineering.

Submit your paper and select the Journal “ChemEngineering” and the Special Issue “Process Intensification for Chemical Engineering and Processing” via: MDPI submission system. Our papers will be published on a rolling basis and we will be pleased to receive your submission once you have finished it.

Prof. Dr. Thomas Grützner
Prof. Dr. Bernhard Seyfang
Guest Editors

Manuscript Submission Information

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Keywords

  • Process intensification
  • Process optimization
  • Combined unit operations
  • Energy-efficient processes
  • Process integration

Published Papers (11 papers)

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Research

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22 pages, 10512 KiB  
Article
Formulation and Characterization of Double Emulsions W/O/W Stabilized by Two Natural Polymers with Two Manufacturing Processes (Comparative Study)
by Meriem Boudoukhani, Madiha Melha Yahoum, Kaouther Ezzroug, Selma Toumi, Sonia Lefnaoui, Nadji Moulai-Mostefa, Asma Nour El Houda Sid, Hichem Tahraoui, Mohammed Kebir, Abdeltif Amrane, Bassem Jaouadi and Jie Zhang
ChemEngineering 2024, 8(2), 34; https://doi.org/10.3390/chemengineering8020034 - 14 Mar 2024
Viewed by 468
Abstract
Four distinct types of multiple emulsions were synthesized using xanthan gum and pectin through two distinct manufacturing processes. The assessment encompassed the examination of morphology, stability, and rheological properties for the resulting water-in-oil-in-water (W/O/W) double emulsions. Formulations were meticulously crafted with emulsifiers that [...] Read more.
Four distinct types of multiple emulsions were synthesized using xanthan gum and pectin through two distinct manufacturing processes. The assessment encompassed the examination of morphology, stability, and rheological properties for the resulting water-in-oil-in-water (W/O/W) double emulsions. Formulations were meticulously crafted with emulsifiers that were compatible with varying compositions. Remarkably stable multiple emulsions were achieved with a 0.5 wt% xanthan concentration, demonstrating resilience for nearly two months across diverse storage temperatures. In contrast, multiple emulsions formulated with a higher pectin concentration (2.75 wt%) exhibited instability within a mere three days. All multiple emulsions displayed shear-thinning behavior, characterized by a decline in apparent viscosity with escalating shear rates. Comparatively, multiple emulsions incorporating xanthan gum showcased elevated viscosity at low shear rates in contrast to those formulated with pectin. These results underscore the pivotal role of the stepwise process over the direct approach and emphasize the direct correlation between biopolymer concentration and emulsion stability. This present investigation demonstrated the potential use of pectin and xanthan gum as stabilizers of multiple emulsions with potential application in the pharmaceutical industry for the formulation of topical dosage forms. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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22 pages, 3462 KiB  
Article
Insight into the Structural and Dynamical Processes of Peptides by Means of Vibrational and Ultrasonic Relaxation Spectroscopies, Molecular Docking, and Density Functional Theory Calculations
by Afrodite Tryfon, Panagiota Siafarika, Constantine Kouderis and Angelos G. Kalampounias
ChemEngineering 2024, 8(1), 21; https://doi.org/10.3390/chemengineering8010021 - 06 Feb 2024
Viewed by 878
Abstract
We report a detailed investigation of the vibrational modes, structure, and dynamics of glutathione (GSH) solutions using ultrasonic relaxation spectroscopy, FT-IR vibrational spectroscopy, and electronic absorption measurements. The experimental data were analyzed using density functional theory (DFT) and molecular docking calculations. Three distinct [...] Read more.
We report a detailed investigation of the vibrational modes, structure, and dynamics of glutathione (GSH) solutions using ultrasonic relaxation spectroscopy, FT-IR vibrational spectroscopy, and electronic absorption measurements. The experimental data were analyzed using density functional theory (DFT) and molecular docking calculations. Three distinct Debye-type relaxation processes can be observed in the acoustic spectra, which are assigned to conformational changes between GSH conformers, the self-association of GSH, and protonation processes. The standard volume changes for each process were estimated both experimentally and theoretically, revealing a close resemblance among them. The higher the effect of the relaxation process in the structure, the greater the induced volume changes. From the temperature dependence of specific acoustic parameters, the thermodynamic characteristics of each process were determined. The experimental FT-IR spectra were compared with the corresponding theoretically predicted vibrational spectra, revealing that the GSH dimers and extended conformers dominate the structure of GSH solutions in the high-concentration region. The absorption spectra in the ultraviolet region confirmed the gradual aggregation mechanism that takes place in the aqueous GSH solutions. The results of the present study were discussed and analyzed in the framework of the current phenomenological status of the field. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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14 pages, 1130 KiB  
Article
Sequential Extraction of Carbohydrates and Lipids from Chlorella vulgaris Using Combined Physical and Chemical Pre-Treatments
by William Hammann, Andrew Ross and Wayne Seames
ChemEngineering 2024, 8(1), 11; https://doi.org/10.3390/chemengineering8010011 - 05 Jan 2024
Viewed by 1364
Abstract
A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered [...] Read more.
A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered and ultimately converted into useful chemical intermediates, this may improve the economics for microalgae-based sustainable product technologies. In the present work, physical and chemical pre-treatments were performed on the Chlorella vulgaris microalgae strain to recover the carbohydrates from the biomass primarily in the form of glucose and galactose. The effects of temperature, acid concentration, microalgae solid-to-liquid loading, and hydrolysis time on carbohydrate hydrolysis and recovery was explored to identify optimum conditions. The highest recovery of total carbohydrates, 90 ± 1.1 wt% at 95% confidence which represents 40 wt% of the initial biomass, was obtained using temperature-assisted weak-acid extraction. Sequential extraction of carbohydrates and lipids was then explored. The highest recovery of total lipids was 71 ± 1.8 wt%, which represents 22 ± 0.9 wt% of the initial biomass. The sequential extraction of carbohydrates followed by lipids resulted in an overall recovery of 60 ± 1.6 wt% of the initial biomass, which is higher than current single product recovery strategies. These results suggest that adding carbohydrate recovery may be a viable strategy for overcoming a major economic hurdle to microalgae-derived chemical and fuel production by significantly increasing the yield of usable materials from microalgae biomass. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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11 pages, 2000 KiB  
Article
Interconversion and Removal of Inorganic Nitrogen Compounds via UV Irradiation
by Alejandro M. Senn and Natalia Quici
ChemEngineering 2023, 7(5), 79; https://doi.org/10.3390/chemengineering7050079 - 31 Aug 2023
Viewed by 946
Abstract
Dissolved inorganic nitrogen (DIN) species are key components of the nitrogen cycle and are the main nitrogen pollutants in groundwater. This study investigated the interconversion and removal of the principal DIN compounds (NO3, NO2 and [...] Read more.
Dissolved inorganic nitrogen (DIN) species are key components of the nitrogen cycle and are the main nitrogen pollutants in groundwater. This study investigated the interconversion and removal of the principal DIN compounds (NO3, NO2 and NH4+) via UV light irradiation using a medium-pressure mercury lamp. The experiments were carried out systematically at relatively low nitrogen concentrations (1.5 mM) at varying pHs in the presence and absence of oxygen to compare the reaction rates and suggest the reaction mechanisms. NO3 was fully converted into NO2 at a pH > 3 in both oxic and anoxic conditions, and the reaction was faster when the pH was increased following a first-order kinetic at pH 11 (k = 0.12 min−1, R2 = 0.9995). NO2 was partially converted into NO3 only at pH 3 and in the presence of oxygen and was stable at an alkaline pH. This interconversion of NO3 and NO2 did not yield nitrogen loss in the solution. The addition of formic acid as an electron donor led to the reduction of NO3 to NH4+. Conversely, NH4+ was converted into NO2, NO3 and to an unidentified subproduct in the presence of O2  at pH 10. Finally, it was demonstrated that NO2 and NH4+ react via UV irradiation with stoichiometry 1:1 at pH 10 with the total loss of nitrogen in the solution. With these results, a strategy to remove DIN compounds via UV irradiation was proposed with the eventual use of solar light. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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16 pages, 7795 KiB  
Article
Experimental Investigation of Heat Losses in a Pilot-Scale Multiple Dividing Wall Distillation Column with Three Parallel Sections
by Lena-Marie Ränger, Yannick Waibel and Thomas Grützner
ChemEngineering 2023, 7(4), 68; https://doi.org/10.3390/chemengineering7040068 - 26 Jul 2023
Viewed by 1076
Abstract
For an in-depth investigation of the separation process in small-scale distillation columns, knowledge about the exact vapor load inside the column is highly important. However, since columns with small diameters have a comparatively high surface-to-volume ratio, heat losses have a significant impact on [...] Read more.
For an in-depth investigation of the separation process in small-scale distillation columns, knowledge about the exact vapor load inside the column is highly important. However, since columns with small diameters have a comparatively high surface-to-volume ratio, heat losses have a significant impact on fluid dynamics, as they lead to unwanted condensation, and thus, to changes in the internal flows. This work presents a procedure used to measure heat losses in a 9.6 m high distillation column with three partially parallel segments (multiple dividing wall column). The evaporator is made of stainless steel, and the column walls are made of double-walled, evacuated, mirrored glass, and additionally, these can be heated. It is found that significant amounts of heat are lost in the evaporator. Throughout the column height, around 0.8 kW are additionally lost, even with external wall heating. To determine the main reason for this significant loss, thermal images are taken, indicating that the problem mainly arises because of the flanges. Based on this, it can be concluded that proper insulation and additional heating jackets for the column walls are highly recommended for small-scale distillation columns in order to increase their thermal efficiency. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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16 pages, 3399 KiB  
Article
Evaluation of Jet Flooding in Distillation Column Olefins Plant on Naphtha to LPG Feed Substitution
by Albertus Wijanarko, Muslikhin Hidayat and Sutijan Sutijan
ChemEngineering 2023, 7(4), 63; https://doi.org/10.3390/chemengineering7040063 - 20 Jul 2023
Viewed by 2616
Abstract
The naphtha cracking process is the most commonly used technology for the production of ethylene, propylene, mixed C4s (including 1,3-butadiene and other C4 components), and pygas (pyrolysis gasoline, a mixture of benzene, toluene, and xylene), all of which are olefins. The cracking [...] Read more.
The naphtha cracking process is the most commonly used technology for the production of ethylene, propylene, mixed C4s (including 1,3-butadiene and other C4 components), and pygas (pyrolysis gasoline, a mixture of benzene, toluene, and xylene), all of which are olefins. The cracking furnace and distillation columns are the primary operational units. The raw material is cracked and undergoes reactions in the cracking furnaces, while the distillation columns are responsible for separating the products. Raw material costs account for 80% of production costs. There is also the possibility of using LPG as a less expensive alternative to some of the naphtha. However, changing the raw material would affect the operability of the distillation columns and influence the yield on the cracking side. To determine the optimal naphtha substitution for LPG without causing hydraulic problems (such as jet flooding) in the distillation columns, analysis using simulation tools must be conducted. A reliability model is being developed to simulate the substitution of naphtha with other feed stocks by comparing simulation results with data from the actual plant. The LPG flow is a variable that is freely adjusted to substitute for naphtha. Simulation tools can be used to assess the effects of economically advantageous naphtha substitution for LPG without compromising plant operability. The optimum naphtha substitution rate is 21.14% from the base case, resulting in jet flooding occurring at Propylene Fractionator No. 2. By implementing this substitution, the benefits that can be obtained amount to USD 22,772.02 per hour. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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13 pages, 1582 KiB  
Article
One-Dimensional Modeling of Mass Transfer Processes in an Annular Centrifugal Contactor
by Peter M. Ritzler, Clemens K. Weiss and Bernhard C. Seyfang
ChemEngineering 2023, 7(4), 59; https://doi.org/10.3390/chemengineering7040059 - 12 Jul 2023
Viewed by 1268
Abstract
Due to the importance of process intensification, modeling of Annular Centrifugal Contactors (ACCs) is becoming of increasing interest. By the current state of scientific knowledge, universal modeling without high computing power of these complex apparatuses is not possible to a satisfactory degree. In [...] Read more.
Due to the importance of process intensification, modeling of Annular Centrifugal Contactors (ACCs) is becoming of increasing interest. By the current state of scientific knowledge, universal modeling without high computing power of these complex apparatuses is not possible to a satisfactory degree. In this article, a one-dimensional model to describe the mass transfer during a physical extraction process in an ACC is presented. The model is based on solely geometrical data and operating conditions of the ACC, as well as physical properties of the components. Regarding the selection of physical properties, only physical properties that are easily accessible were used. With this model, mass transfer calculations are possible and therefore, the output concentrations can be predicted. Simulations of an ACC based on the model were done by creating and running a python code. Validation of the model was conducted by varying and comparing operating conditions in both the simulation and the experiments. Validation was completed successfully for a representative system of components and showed good agreement over a range of rotational frequencies and temperatures. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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19 pages, 5884 KiB  
Article
Method for Intensive Gas–Liquid Dispersion in a Stirred Tank
by Nikolai A. Voinov, Alexander S. Frolov, Anastasiya V. Bogatkova, Denis A. Zemtsov and Olga P. Zhukova
ChemEngineering 2023, 7(2), 30; https://doi.org/10.3390/chemengineering7020030 - 04 Apr 2023
Viewed by 1335
Abstract
This article presents the results of hydrodynamics and mass exchange in a stirred tank upon the introduction of gas from an open gas vortex cavity into local liquid regions with reduced pressure. It establishes conditions for the intensive dispersion of gas. Velocity fields [...] Read more.
This article presents the results of hydrodynamics and mass exchange in a stirred tank upon the introduction of gas from an open gas vortex cavity into local liquid regions with reduced pressure. It establishes conditions for the intensive dispersion of gas. Velocity fields and liquid pressure behind the stirrer paddles are determined by numerical simulation in OpenFOAM. The gas content value, gas bubble diameters, and phase surface are determined experimentally. The stirrer power criterion is calculated by taking into account the gas content and power input. The experimental mass transfer data based on the absorption of atmospheric oxygen into water during the dispersion of gas from the open vortex cavity in the local liquid regions behind the rotating stirrer paddles are presented. In this case, the energy dissipation from the rotating stirrer reaches 25 W/kg, with a phase surface of 1000 m−1 and a surface mass transfer coefficient of up to 0.3·10−3 m/s. These parameters are obviously higher than the data obtained in the apparatus for mass exchange through surface vorticity. The advantage of the given method for gas dispersion in a liquid is the functional stability of the apparatus regardless of how deep the stirrer is immersed in the liquid or the temperature or pressure of the gas. Apparatuses based on the intensive gas dispersion method allow for varying the mass transfer coefficient and gas content across a broad range of values. This allows establishing a dependency between the experimentally obtained mass transfer coefficient, energy dissipation, and phase surface values. An equation for calculating the mass transfer coefficient is formulated by taking into account the geometric parameters of the stirrer apparatus based on the stirring power and phase surface values. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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18 pages, 1709 KiB  
Article
A Framework for Multi-Objective Optimization of Plate-Fin Heat Exchangers Using a Detailed Three-Dimensional Simulation Model
by Patrick Haider, Paul Heinz, Thomas Acher, Sebastian Rehfeldt and Harald Klein
ChemEngineering 2021, 5(4), 82; https://doi.org/10.3390/chemengineering5040082 - 02 Dec 2021
Cited by 2 | Viewed by 2950
Abstract
The design of a multi-stream plate-fin heat exchanger is a highly integrated task with multiple opposing objectives and many degrees of freedom. This work shows how it can be fully or partially automated by the combination of a detailed three-dimensional simulation model and [...] Read more.
The design of a multi-stream plate-fin heat exchanger is a highly integrated task with multiple opposing objectives and many degrees of freedom. This work shows how it can be fully or partially automated by the combination of a detailed three-dimensional simulation model and an optimization routine. The desired task is formulated as the target of a multi-objective optimization and solved using a genetic algorithm. The workflow is presented using a cryogenic plate-fin heat exchanger with four process streams. The design is optimized towards high efficiency, low pressure drop, and low unit weight by adjusting the outer geometry, the inlet and outlet distributor configuration, and the detailed stream geometry. A detailed analysis of the Pareto-set gives a good overview of possible solutions, and the optimization routine can automatically find a feasible design with a reasonable tradeoff between the objectives. All elements of the framework are implemented in open source software. A highlight of this research is that a very comprehensive and detailed simulation model is employed in the optimization framework. Thus, the presented method can be easily adjusted to fit the needs of other engineering tasks. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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21 pages, 2095 KiB  
Article
Impact of Various Feed Properties on the Performance of a Control System for a Multiple Dividing Wall Column Pilot Plant
by Ulrich Preißinger, Goran Lukač, Igor Dejanović and Thomas Grützner
ChemEngineering 2021, 5(2), 29; https://doi.org/10.3390/chemengineering5020029 - 08 Jun 2021
Cited by 2 | Viewed by 2477
Abstract
Despite the attractive savings potential of multiple Dividing Wall Columns (mDWC), there are no reports in the open literature of an existing application so far. In this perspective, the control of mDWCs has been a rather little-investigated field. Pilot plants are a necessary [...] Read more.
Despite the attractive savings potential of multiple Dividing Wall Columns (mDWC), there are no reports in the open literature of an existing application so far. In this perspective, the control of mDWCs has been a rather little-investigated field. Pilot plants are a necessary step needed to further expand the application window of this sustainable distillation technology. This contribution aimed to show that mDWCs are sufficiently flexible, providing stable operation, even with suboptimal control structures arising from design limitations imposed by equipment. For this purpose, the pilot column design was assessed using dynamic simulation to evaluate its operability in case of different disturbances as well as different feed mixtures. The results showed that, in all cases, the column could be stabilized and product purities maintained. This suggests that even complex configurations such as mDWCs offer sufficient amount of flexibility to allow for the application of one design in different services. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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Review

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18 pages, 1303 KiB  
Review
Process Intensification Strategies for Power-to-X Technologies
by Thomas Cholewa, Malte Semmel, Franz Mantei, Robert Güttel and Ouda Salem
ChemEngineering 2022, 6(1), 13; https://doi.org/10.3390/chemengineering6010013 - 02 Feb 2022
Cited by 12 | Viewed by 3925
Abstract
Sector coupling remains a crucial measure to achieve climate change mitigation targets. Hydrogen and Power-to-X (PtX) products are recognized as major levers to allow the boosting of renewable energy capacities and the consequent use of green electrons in different sectors. In this work, [...] Read more.
Sector coupling remains a crucial measure to achieve climate change mitigation targets. Hydrogen and Power-to-X (PtX) products are recognized as major levers to allow the boosting of renewable energy capacities and the consequent use of green electrons in different sectors. In this work, the challenges presented by the PtX processes are addressed and different process intensification (PI) strategies and their potential to overcome these challenges are reviewed for ammonia (NH3), dimethyl ether (DME) and oxymethylene dimethyl ethers (OME) as three exemplary, major PtX products. PI approaches in this context offer on the one hand the maximum utilization of valuable renewable feedstock and on the other hand simpler production processes. For the three discussed processes a compelling strategy for efficient and ultimately maintenance-free chemical synthesis is presented by integrating unit operations to overcome thermodynamic limitations, and in best cases eliminate the recycle loops. The proposed intensification processes offer a significant reduction of energy consumption and provide an interesting perspective for the future development of PtX technologies. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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