ChemEngineering

31 pages, 22503 KiB

Open AccessArticle

Scaling of Droplet Breakup in High-Pressure Homogenizer Orifices. Part II: Visualization of the Turbulent Droplet Breakup

by Benedikt Mutsch, Felix Johannes Preiss, Teresa Dagenbach, Heike Petra Karbstein and Christian J. Kähler

ChemEngineering 2021, 5(2), 31; https://doi.org/10.3390/chemengineering5020031 - 18 Jun 2021

Cited by 12 | Viewed by 2979

Abstract

Emulsion formation is of great interest in the chemical and food industry and droplet breakup is the key process. Droplet breakup in a quiet or laminar flow is well understood, however, actual in-dustrial processes are always in the turbulent flow regime, leading to [...] Read more.

Emulsion formation is of great interest in the chemical and food industry and droplet breakup is the key process. Droplet breakup in a quiet or laminar flow is well understood, however, actual in-dustrial processes are always in the turbulent flow regime, leading to more complex droplet breakup phenomena. Since high resolution optical measurements on microscopic scales are extremely dif-ficult to perform, many aspects of the turbulent droplet breakup are physically unclear. To over-come this problem, scaled experimental setups (with scaling factors of 5 and 50) are used in con-junction with an original scale setup for reference. In addition to the geometric scaling, other non-dimensional numbers such as the Reynolds number, the viscosity ratio and the density ratio were kept constant. The scaling allows observation of the phenomena on macroscopic scales, whereby the objective is to show that the scaling approach makes it possible to directly transfer the findings from the macro- to the micro-/original scale. In this paper, which follows Part I where the flow fields were compared and found to be similar, it is shown by breakup visualizations that the turbulent droplet breakup process is similar on all scales. This makes it possible to transfer the results of detailed parameter variations investigated on the macro scale to the micro scale. The evaluation and analysis of the results imply that the droplet breakup is triggered and strongly influenced by the intensity and scales of the turbulent flow motion. Full article

(This article belongs to the Special Issue Emulsion Process Design)

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57 pages, 1867 KiB

Open AccessArticle

How to Modify LAMMPS: From the Prospective of a Particle Method Researcher

by Andrea Albano, Eve le Guillou, Antoine Danzé, Irene Moulitsas, Iwan H. Sahputra, Amin Rahmat, Carlos Alberto Duque-Daza, Xiaocheng Shang, Khai Ching Ng, Mostapha Ariane and Alessio Alexiadis

ChemEngineering 2021, 5(2), 30; https://doi.org/10.3390/chemengineering5020030 - 13 Jun 2021

Cited by 6 | Viewed by 8870

Abstract

LAMMPS is a powerful simulator originally developed for molecular dynamics that, today, also accounts for other particle-based algorithms such as DEM, SPH, or Peridynamics. The versatility of this software is further enhanced by the fact that it is open-source and modifiable by users. [...] Read more.

LAMMPS is a powerful simulator originally developed for molecular dynamics that, today, also accounts for other particle-based algorithms such as DEM, SPH, or Peridynamics. The versatility of this software is further enhanced by the fact that it is open-source and modifiable by users. This property suits particularly well Discrete Multiphysics and hybrid models that combine multiple particle methods in the same simulation. Modifying LAMMPS can be challenging for researchers with little coding experience. The available material explaining how to modify LAMMPS is either too basic or too advanced for the average researcher. In this work, we provide several examples, with increasing level of complexity, suitable for researchers and practitioners in physics and engineering, who are familiar with coding without been experts. For each feature, step by step instructions for implementing them in LAMMPS are shown to allow researchers to easily follow the procedure and compile a new version of the code. The aim is to fill a gap in the literature with particular reference to the scientific community that uses particle methods for (discrete) multiphysics. Full article

(This article belongs to the Special Issue Discrete Multiphysics: Modelling Complex Systems with Particle Methods)

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21 pages, 2095 KiB

Open AccessArticle

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 2580

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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13 pages, 2974 KiB

Open AccessArticle

Improved Catalytic Activity of the High-Temperature Water Gas Shift Reaction on Metal-Exsolved La_0.9Ni_0.05Fe_0.95O₃ by Controlling Reduction Time

by Rui Huang and Jeong Woo Han

ChemEngineering 2021, 5(2), 28; https://doi.org/10.3390/chemengineering5020028 - 07 Jun 2021

Cited by 5 | Viewed by 3632

Abstract

The catalyst exsolved from nickel-doped perovskite oxide, La_0.9Ni_0.05Fe_0.95O₃, has been proven to be effective for gas-phase reactions. To obtain the optimum amount of exsolved nanoparticles from the parent perovskite oxide, control of the reduction treatment [...] Read more.

The catalyst exsolved from nickel-doped perovskite oxide, La_0.9Ni_0.05Fe_0.95O₃, has been proven to be effective for gas-phase reactions. To obtain the optimum amount of exsolved nanoparticles from the parent perovskite oxide, control of the reduction treatment condition is vital. Here, the effect of reduction time on the exsolved nanoparticle distribution, and thus the catalytic activity of the high-temperature water gas shift reaction (WGSR), was investigated. Upon conducting a wide range of characterizations, we assumed that the exsolution process might be a two-step process. Firstly, the surface oxygen is extracted. Secondly, due to the unstable perovskite structure, the Ni ions in the bulk La_0.9Ni_0.05Fe_0.95O₃ continuously diffuse toward the surface and, as the reduction progresses, more nuclei are generated to form a greater number of nanoparticles. This assumption is proven by the fact that, with an increase in the exsolution treatment time, the population of exsolution nanoparticles increases. Moreover, as the reduction time increases, the high-temperature WGSR activity also increases. The temperature-programmed measurements suggest that the exsolved nanoparticles are the active reaction sites. We believe that this study is helpful for understanding exsolution behavior during reduction treatment and, thus, developing a perovskite exsolution catalyst for the WGSR. Full article

(This article belongs to the Special Issue Functional Oxides for Heterogeneous Catalysis)

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14 pages, 3549 KiB

Open AccessArticle

Consumer Attitudes towards Microalgae Production and Microalgae-Based Agricultural Products: The Cases of Almería (Spain) and Livorno (Italy)

by Tomás Lafarga, Carlo Pieroni, Giuliana D’Imporzano, Lorenzo Maggioni, Fabrizio Adani and Gabriel Acién

ChemEngineering 2021, 5(2), 27; https://doi.org/10.3390/chemengineering5020027 - 28 May 2021

Cited by 11 | Viewed by 3330

Abstract

The production of microalgal biomass and products derived thereof for a wide variety of applications is a hot research topic, with the number of facilities being built and products and biologically active molecules launched into the market increasing every year. The aim of [...] Read more.

The production of microalgal biomass and products derived thereof for a wide variety of applications is a hot research topic, with the number of facilities being built and products and biologically active molecules launched into the market increasing every year. The aim of the current study was to identify the attitudes of citizens in Almería (Spain) and Livorno (Italy) towards the construction of a microalgae production plant and a biorefinery in their cities and also their opinions about the microalgae-based products that could be produced. Overall, in Almería (Spain), a NIMBY (not in my back yard) attitude towards the construction of a microalgal production facility and especially towards a microalgal biorefinery was observed, despite the strong microalgal industry in the region and the higher knowledge of citizens about microalgae. In both locations, but especially in Livorno (Italy), microalgae-based biostimulants, biofertilisers, and aquafeeds were well accepted. Proximity was the main factor affecting the acceptance of a microalgae producing facility. Consumer knowledge about microalgal biotechnology and the health and environmental benefits of this valuable raw material are scarce, and opinions are based on drivers other than knowledge. After gaining more knowledge about microalgal biorefineries, most of the responses in Almería (47%) and Livorno (61%) were more positive. Full article

(This article belongs to the Special Issue Industrial Cultivation of Microalgae: Technologies, Applications and Challenges)

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3 pages, 661 KiB

Open AccessEditorial

Heterogeneous Photocatalysis

by Mario J. Muñoz-Batista and Rafael Luque

ChemEngineering 2021, 5(2), 26; https://doi.org/10.3390/chemengineering5020026 - 25 May 2021

Cited by 11 | Viewed by 2583

Abstract

Heterogeneous photocatalysis is a subtype of catalysis that refers to chemical processes catalysed by a semiconductor solid under proper illumination conditions [...] Full article

(This article belongs to the Special Issue Heterogeneous Photocatalysis and Photocatalytic Nanomaterials)

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11 pages, 2062 KiB

Open AccessArticle

Evaluation of Pulsed Electric Field Polyphenol Extraction from Vitis vinifera, Sideritis scardica and Crocus sativus

by Achillia Lakka, Eleni Bozinou, Dimitris P. Makris and Stavros I. Lalas

ChemEngineering 2021, 5(2), 25; https://doi.org/10.3390/chemengineering5020025 - 13 May 2021

Cited by 24 | Viewed by 3528

Abstract

This study exploited the application of pulsed electric field (PEF) on the recovery of polyphenols from aerial parts of Sideritis scardica, tepals of Crocus sativus, and fruits of Vitis vinifera. Short pulses of 10 μs in a period of 1 ms [...] Read more.

This study exploited the application of pulsed electric field (PEF) on the recovery of polyphenols from aerial parts of Sideritis scardica, tepals of Crocus sativus, and fruits of Vitis vinifera. Short pulses of 10 μs in a period of 1 ms were applied to the plant material, while different electric field intensities, 1.2 to 2.0 kV/cm were tested to optimize the procedure. The content in total polyphenols and the polyphenolic profile of the plant extracts were evaluated. Along with PEF samples, control samples were prepared for comparison. PEF treatment enhanced the recovery in total polyphenols for all the three plants examined. A significant increase was noticed in each plant tested and PEF condition applied, though lower electric field intensities up to 1.4 kV/cm proved to be more effective. Under the optimum electric field intensities, 1.4 kV/cm for V. vinifera and 1.2 kV/cm for S. scardica and C. sativus, increases of 49.15%, 35.25%, and 44.36% in total polyphenol content, respectively, were achieved. Additionally, an 85% increase of quercetin 3-rutinoside for V. vinifera, a 56% of apigenin 7-O-glucoside for S. scardica, and a 64% increase for kaempferol 3-O-glucoside for C. sativus were obtained. Full article

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21 pages, 4494 KiB

Open AccessArticle

Group Contribution Revisited: The Enthalpy of Formation of Organic Compounds with “Chemical Accuracy”

by Robert J. Meier

ChemEngineering 2021, 5(2), 24; https://doi.org/10.3390/chemengineering5020024 - 11 May 2021

Cited by 12 | Viewed by 3312

Abstract

Group contribution (GC) methods to predict thermochemical properties are of eminent importance to process design. Compared to previous works, we present an improved group contribution parametrization for the heat of formation of organic molecules exhibiting chemical accuracy, i.e., a maximum 1 kcal/mol (4.2 [...] Read more.

Group contribution (GC) methods to predict thermochemical properties are of eminent importance to process design. Compared to previous works, we present an improved group contribution parametrization for the heat of formation of organic molecules exhibiting chemical accuracy, i.e., a maximum 1 kcal/mol (4.2 kJ/mol) difference between the experiment and model, while, at the same time, minimizing the number of parameters. The latter is extremely important as too many parameters lead to overfitting and, therewith, to more or less serious incorrect predictions for molecules that were not within the data set used for parametrization. Moreover, it was found to be important to explicitly account for common chemical knowledge, e.g., geminal effects or ring strain. The group-related parameters were determined step-wise: first, alkanes only, and then only one additional group in the next class of molecules. This ensures unique and optimal parameter values for each chemical group. All data will be made available, enabling other researchers to extend the set to other classes of molecules. Full article

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18 pages, 2545 KiB

Open AccessArticle

Activated Carbons for Syngas Desulfurization: Evaluating Approaches for Enhancing Low-Temperature H₂S Oxidation Rate

by Christian Frilund, Ilkka Hiltunen and Pekka Simell

ChemEngineering 2021, 5(2), 23; https://doi.org/10.3390/chemengineering5020023 - 11 May 2021

Cited by 4 | Viewed by 3894

Abstract

Its relatively low cost and high surface area makes activated carbon an ideal adsorbent candidate for H₂S removal. However, physical adsorption of H₂S is not very effective; therefore, methods to facilitate reactive H₂S oxidation on carbons are [...] Read more.

Its relatively low cost and high surface area makes activated carbon an ideal adsorbent candidate for H₂S removal. However, physical adsorption of H₂S is not very effective; therefore, methods to facilitate reactive H₂S oxidation on carbons are of interest. The performance of H₂S removal of non-impregnated, impregnated, and doped activated carbon in low-temperature syngas was evaluated in fixed-bed breakthrough tests. The importance of oxygen content and relative humidity was established for reactive H₂S removal. Impregnates especially improved the adsorption rate compared to non-impregnated carbons. Non-impregnated carbons could however retain a high capture capacity with sufficient contact time. In a relative performance test, the best performance was achieved by doped activated carbon, 320 mg g⁻¹. Ammonia in syngas was found to significantly improve the adsorption rate of non-impregnated activated carbon. A small quantity of ammonia was consumed by the carbon bed, suggesting that ammonia is a reactant. Finally, to validate ammonia-enhanced desulfurization, bench-scale experiments were performed in biomass-based gasification syngas. The results show that when the ammonia concentration in syngas was in the tens of ppm range, 40–160 ppm H₂S oxidation proceeded rapidly. Ammonia-enhanced oxidation allows utilization of cheaper non-impregnated activated carbons by in situ improvement of the adsorption kinetics. Ammonia enhancement is therefore established as a viable method for achieving high-capacity H₂S removal with unmodified activated carbons. Full article

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15 pages, 40304 KiB

Open AccessArticle

Simplified Approach to Predict Food Safety through the Maximum Specific Bacterial Growth Rate as Function of Extrinsic and Intrinsic Parameters

by Pedro D. Gaspar, Joel Alves and Pedro Pinto

ChemEngineering 2021, 5(2), 22; https://doi.org/10.3390/chemengineering5020022 - 10 May 2021

Cited by 8 | Viewed by 2526

Abstract

Currently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict [...] Read more.

Currently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict changes in the food quality and allow decision-making for expiration dates. To perform that, the Baranyi and Roberts model and the online tool Combined Database for Predictive Microbiology (Combase) were used to determine the factors that define the growth of different bacteria. These factors applied to the equation that determines the maximum specific growth rate establish a relation between the bacterial growth and the intrinsic and extrinsic factors that define the bacteria environment. These models may be programmed in low-cost wireless biochemical sensor devices applied to packaging and food supply chains to promote food safety and quality through real time traceability. Full article

(This article belongs to the Special Issue Bio-Processing and Biochemical Engineering 2021)

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22 pages, 1300 KiB

Open AccessArticle

Fortran Coarray Implementation of Semi-Lagrangian Convected Air Particles within an Atmospheric Model

by Soren Rasmussen, Ethan D. Gutmann, Irene Moulitsas and Salvatore Filippone

ChemEngineering 2021, 5(2), 21; https://doi.org/10.3390/chemengineering5020021 - 06 May 2021

Viewed by 2933

Abstract

This work added semi-Lagrangian convected air particles to the Intermediate Complexity Atmospheric Research (ICAR) model. The ICAR model is a simplified atmospheric model using quasi-dynamical downscaling to gain performance over more traditional atmospheric models. The ICAR model uses Fortran coarrays to split the [...] Read more.

This work added semi-Lagrangian convected air particles to the Intermediate Complexity Atmospheric Research (ICAR) model. The ICAR model is a simplified atmospheric model using quasi-dynamical downscaling to gain performance over more traditional atmospheric models. The ICAR model uses Fortran coarrays to split the domain amongst images and handle the halo region communication of the image’s boundary regions. The newly implemented convected air particles use trilinear interpolation to compute initial properties from the Eulerian domain and calculate humidity and buoyancy forces as the model runs. This paper investigated the performance cost and scaling attributes of executing unsaturated and saturated air particles versus the original particle-less model. An in-depth analysis was done on the communication patterns and performance of the semi-Lagrangian air particles, as well as the performance cost of a variety of initial conditions such as wind speed and saturation mixing ratios. This study found that given a linear increase in the number of particles communicated, there is an initial decrease in performance, but that it then levels out, indicating that over the runtime of the model, there is an initial cost of particle communication, but that the computational benefits quickly offset it. The study provided insight into the number of processors required to amortize the additional computational cost of the air particles. Full article

(This article belongs to the Special Issue Discrete Multiphysics: Modelling Complex Systems with Particle Methods)

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24 pages, 6029 KiB

Open AccessArticle

Simulation of a Downdraft Gasifier for Production of Syngas from Different Biomass Feedstocks

by Mateus Paiva, Admilson Vieira, Helder T. Gomes and Paulo Brito

ChemEngineering 2021, 5(2), 20; https://doi.org/10.3390/chemengineering5020020 - 05 May 2021

Cited by 8 | Viewed by 5302

Abstract

In the evaluation of gasification processes, estimating the composition of the fuel gas for different conditions is fundamental to identify the best operating conditions. In this way, modeling and simulation of gasification provide an analysis of the process performance, allowing for resource and [...] Read more.

In the evaluation of gasification processes, estimating the composition of the fuel gas for different conditions is fundamental to identify the best operating conditions. In this way, modeling and simulation of gasification provide an analysis of the process performance, allowing for resource and time savings in pilot-scale process operation, as it predicts the behavior and analyzes the effects of different variables on the process. Thus, the focus of this work was the modeling and simulation of biomass gasification processes using the UniSim Design chemical process software, in order to satisfactorily reproduce the operation behavior of a downdraft gasifier. The study was performed for two residual biomasses (forest and agricultural) in order to predict the produced syngas composition. The reactors simulated gasification by minimizing the free energy of Gibbs. The main operating parameters considered were the equivalence ratio (ER), steam to biomass ratio (SBR), and gasification temperature (independent variables). In the simulations, a sensitivity analysis was carried out, where the effects of these parameters on the composition of syngas, flow of syngas, and heating value (dependent variables) were studied, in order to maximize these three variables in the process with the choice of the best parameters of operation. The model is able to predict the performance of the gasifier and it is qualified to analyze the behavior of the independent parameters in the gasification results. With a temperature between 850 and 950 °C, SBR up to 0.2, and ER between 0.3 and 0.5, the best operating conditions are obtained for maximizing the composition of the syngas in CO and H₂. Full article

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11 pages, 2964 KiB

Open AccessArticle

Synthesis of Non-Cubic Nitride Phases of Va-Group Metals (V, Nb, and Ta) from Metal Powders in Stream of NH₃ Gas under Concentrated Solar Radiation

by Nobumitsu Shohoji, Fernando Almeida Costa Oliveira, José Galindo, José Rodríguez, Inmaculada Cañadas, Jorge Cruz Fernandes and Luís Guerra Rosa

ChemEngineering 2021, 5(2), 19; https://doi.org/10.3390/chemengineering5020019 - 20 Apr 2021

Cited by 3 | Viewed by 2757

Abstract

Using a high-flux solar furnace, loosely compacted powders of Va-group transition metal (V, Nb, and Ta) were reacted with stream of NH₃ gas (uncracked NH₃ gas) being heated by concentrated solar beam to a temperature (T) range between 600 and 1000 [...] Read more.

Using a high-flux solar furnace, loosely compacted powders of Va-group transition metal (V, Nb, and Ta) were reacted with stream of NH₃ gas (uncracked NH₃ gas) being heated by concentrated solar beam to a temperature (T) range between 600 and 1000 °C. From V, sub-nitride V₂N (γ phase) and hypo-stoichiometric mono-nitride VN possessing fcc (face-centered cubic) crystal lattice structure (δ phase) were synthesized. On the other hand, in the reaction product from Nb and Ta, hexagonal mono-nitride phase with N/M atom ratio close to 1 (ε phase) was detected. The reaction duration was normalized to be 60 min. In a conventional industrial or laboratory electric furnace, the synthesis of mono-nitride phase with high degree of crystallinity that yield sharp XRD peaks for Va-group metal might take a quite long duration even at T exceeding 1000 °C. In contrast, mono–nitride phase MN of Va-group metal was synthesized for a relatively short duration of 60 min at T lower than 1000 °C being co-existed with lower nitride phases. Full article

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Graphical abstract

12 pages, 1167 KiB

Open AccessReview

Review of NMR Studies for Oilwell Cements and Their Importance

by Fatemeh K. Saleh, Catalin Teodoriu and Carl Sondergeld

ChemEngineering 2021, 5(2), 18; https://doi.org/10.3390/chemengineering5020018 - 19 Apr 2021

Viewed by 2485

Abstract

This paper summarizes experimental studies using Nuclear Magnetic Resonance (NMR) to evaluate cement porosity, pore size distribution, and other characteristics such as Calcium Silicate Hydrate (CSH) gel structure and morphology. The first known paper on NMR experiments to investigate cement pastes was published [...] Read more.

This paper summarizes experimental studies using Nuclear Magnetic Resonance (NMR) to evaluate cement porosity, pore size distribution, and other characteristics such as Calcium Silicate Hydrate (CSH) gel structure and morphology. The first known paper on NMR experiments to investigate cement pastes was published in 1978. Two main NMR parameters, the so-called longitudinal T1 and transverse T2 relaxation times, are commonly measured and analyzed, representing the water response which is trapped in the cement. The hydration process reported in this paper was found to be monitored from as low as 10 min to longer than 365 days. Other studies conducted experiments by using NMR, especially during the 1980s. These studies employed variations in methodologies and frequencies, making data comparison difficult. Additionally, different spectrometers and NMR concepts, as well as operating characteristics, were used. Therefore, it is challenging to reconcile results from previous NMR studies on cement. Other significant hurdles are different cement types, water/cement ratio, and curing conditions. One notable observation is that there has not been any comprehensive laboratory work related to NMR on oilfield cement types, including porosity and hydration. Two recent studies have presented NMR measurements on class G and class H cements. Full article

(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)

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16 pages, 1841 KiB

Open AccessArticle

Heat Exchanger Network Retrofit of an Oleochemical Plant through a Cost and Energy Efficiency Approach

by Valli Trisha, Kai Seng Koh, Lik Yin Ng and Vui Soon Chok

ChemEngineering 2021, 5(2), 17; https://doi.org/10.3390/chemengineering5020017 - 12 Apr 2021

Cited by 5 | Viewed by 3086

Abstract

Limited research of heat integration has been conducted in the oleochemical field. This paper attempts to evaluate the performance of an existing heat exchanger network (HEN) of an oleochemical plant at 600 tonnes per day (TPD) in Malaysia, in which the emphases are [...] Read more.

Limited research of heat integration has been conducted in the oleochemical field. This paper attempts to evaluate the performance of an existing heat exchanger network (HEN) of an oleochemical plant at 600 tonnes per day (TPD) in Malaysia, in which the emphases are placed on the annual saving and reduction in energy consumption. Using commercial HEN numerical software, ASPEN Energy Analyzer v10.0, it was found that the performance of the current HEN in place is excellent, saving over 80% in annual costs and reducing energy consumption by 1,882,711 gigajoule per year (GJ/year). Further analysis of the performance of the HEN was performed to identify the potential optimisation of untapped heating/cooling process streams. Two cases, which are the most cost-effective and energy efficient, were proposed with positive results. However, the second case performed better than the first case, at a lower payback time (0.83 year) and higher annual savings (0.20 million USD/year) with the addition of one heat exchanger at a capital cost of USD 134,620. The first case had a higher payback time (4.64 years), a lower annual saving (0.05 million USD/year) and three additional heaters at a capital cost of USD 193,480. This research has provided a new insight into the oleochemical industry in which retrofitting the HEN can further reduce energy consumption, which in return will reduce the overall production cost of oleochemical commodities. This is particularly crucial in making the product more competitive in its pricing in the global market. Full article

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14 pages, 9794 KiB

Open AccessArticle

Waste and Solar Energy: An Eco-Friendly Way for Glass Melting

by Isabel Padilla, Maximina Romero, José I. Robla and Aurora López-Delgado

ChemEngineering 2021, 5(2), 16; https://doi.org/10.3390/chemengineering5020016 - 08 Apr 2021

Cited by 6 | Viewed by 2808

Abstract

In this work, concentrated solar energy (CSE) was applied to an energy-intensive process such as the vitrification of waste with the aim of manufacturing glasses. Different types of waste were used as raw materials: a hazardous waste from the aluminum industry as aluminum [...] Read more.

In this work, concentrated solar energy (CSE) was applied to an energy-intensive process such as the vitrification of waste with the aim of manufacturing glasses. Different types of waste were used as raw materials: a hazardous waste from the aluminum industry as aluminum source; two residues from the food industry (eggshell and mussel shell) and dolomite ore as calcium source; quartz sand was also employed as glass network former. The use of CSE allowed obtaining glasses in the SiO₂-Al₂O₃-CaO system at exposure time as short as 15 min. The raw materials, their mixtures, and the resulting glasses were characterized by means of X-ray fluorescence, X-ray diffraction, and differential thermal analysis. The feasibility of combining a renewable energy, as solar energy and different waste for the manufacture of glasses, would highly contribute to circular economy and environmental sustainability. Full article

(This article belongs to the Special Issue Concentrated Solar Energy for Materials)

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16 pages, 1617 KiB

Open AccessArticle

A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

by Paz Nativ, Yonatan Gräber, Yaron Aviezer and Ori Lahav

ChemEngineering 2021, 5(2), 15; https://doi.org/10.3390/chemengineering5020015 - 06 Apr 2021

Cited by 10 | Viewed by 5657

Abstract

A new analytic approach is presented for determining the total volatile fatty acids (VFA_T) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (C_T) in the analyzed solution, along with two strong-acid titration [...] Read more.

A new analytic approach is presented for determining the total volatile fatty acids (VFA_T) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (C_T) in the analyzed solution, along with two strong-acid titration points. The C_T concentration can be determined by either a direct analysis (e.g., by using a TOC device) or by estimating it from the recorded partial pressure of CO₂(g) in the biogas (often a routine analysis in anaerobic digesters). The titration is carried out to pH 5.25 and then to pH 4.25. The two titration results are plugged into an alkalinity-mass-based equation and then the two terms are subtracted from each other to yield an equation in which VFA_T is the sole unknown (since C_T is known and the effect of the total orthophosphate and ammonia concentrations is shown to be small at this pH range). The development of the algorithm and its verification on four anaerobic reactor liquors is presented, on both the raw water and on acetic acid-spiked samples. The results show the method to be both accurate (up to 2.5% of the expected value for VFA_T/Alkalinity >0.2) and repetitive when the total orthophosphate and ammonia concentrations are known, and fairly accurate (±5% for VFA_T >5 mM) when these are completely neglected. PHREEQC-assisted computation of C_T from the knowledge of the partial pressure of CO₂(g) in the biogas (and pH, EC and temperature in the liquor) resulted in a very good estimation of the C_T value (±3%), indicating that this technique is adequate for the purpose of determining VFA_T for alarming operators in case of process deterioration and imminent failure. Full article

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