Reactor Design Research Articles

Ozone-based advanced oxidation processes in water treatment: recent advances, challenges, and perspective.

Water pollution, driven by a variety of enduring contaminants, poses considerable threats to ecosystems, human health, and biodiversity, highlighting the urgent need for innovative and sustainable treatment approaches. Ozone-based advanced oxidation processes (AOPs) have demonstrated significant efficacy in breaking down stubborn pollutants, such as organic micropollutants and pathogens, that are not easily addressed by traditional treatment techniques. This review offers an in-depth analysis of ozonation mechanisms, covering both the direct oxidation by ozone and the indirect reactions facilitated by hydroxyl radicals, emphasizing their effectiveness and adaptability across various wastewater matrices. Significant progress in the combination of ozonation with additional technologies, including UV irradiation, hydrogen peroxide (H₂O₂), catalytic systems, and biological treatments, is examined, highlighting their effectiveness in enhancing pollutant breakdown, increasing biodegradability, and reducing secondary pollution. Hybrid methods, including catalytic ozonation and ozone-biological treatment, show significant enhancements in process efficiency and cost-effectiveness, while effectively tackling challenges associated with energy use and byproduct generation. Despite the promising possibilities, obstacles remain, such as scalability issues, high operational costs, and the risk of generating potentially harmful transformation products. Cutting-edge approaches, including the creation of sophisticated catalysts, integration of processes, and refinement of reactor designs, are suggested to address these challenges and improve the real-world implementation of ozone-based advanced oxidation processes. This review highlights the significant potential of ozone-based advanced oxidation processes as sustainable approaches for wastewater treatment, providing an essential route to environmental conservation and safeguarding public health.

Batch Reactor Design and Conception at Laboratory Scale for Solid-State Anaerobic Digestion: Practical Comparison Between 3D-Printed Digesters and Conventional Methods

Batch Reactor Design and Conception at Laboratory Scale for Solid-State Anaerobic Digestion: Practical Comparison Between 3D-Printed Digesters and Conventional Methods

An experimental flow regime map to dynamically structure gas–solid bubbling fluidized beds

AbstractEmploying oscillatory gas flows to create ordered bubble dynamics in fluidized beds represents a promising approach in reactor design, enhancing efficiency, scalability, and control. This study reports an extensive experimental campaign that identifies the operational regime for structuring Geldart B fluidized beds, introducing a novel pattern recognition algorithm to quantify flow stability and distinguish between “structured” and “unstructured” oscillating beds. The analysis reveals the characteristic features of structured units, including enhanced scalability, homogeneity with narrower bubble size and separation distributions, controlled bubble dynamics, and compartmentalized solid mixing. A nondimensional bubble size, derived from natural frequency and two‐phase theory, is proposed to describe the relationship between oscillation characteristics and bubble nucleation. This allows the formulation of a general map to fine‐tune oscillating bed operations. The study provides the first comprehensive framework for real‐time control of structured beds and sets the stage for further exploration in process intensification and scaling.

Lunar Power Sources: An Opportunity to Experiment

This paper presents a systematic analysis of power generation technologies for a lunar outpost supporting six astronauts. Based on a detailed power budget analysis requiring 65 kWe for life support, scientific equipment, and in situ resource utilization (ISRU), a comparative analysis of solar and nuclear power solutions is conducted. Nuclear fission is identified as the most promising technology based on key criteria, including mass efficiency, reliability, and power density. A parametric study is then conducted to optimize the nuclear reactor design, with particular focus on radiation shielding using lunar regolith and its impact on safety distances. The analysis demonstrates that proper shielding can reduce the required safety distance from over 2.5 km to approximately 90 m while maintaining radiation exposure within acceptable limits. Finally, leveraging insights from existing reactor designs, an optimized configuration is proposed that combines multiple small reactors to meet the unique challenges of lunar power generation while ensuring crew safety and operational redundancy.

Impact of Solid Particle Concentration and Liquid Circulation on Gas Holdup in Counter-Current Slurry Bubble Columns

In this study, in a three-phase reactor with a rectangular cross-section, the effects of liquid circulation rates and solid particle concentration on gas holdup and bubble size distribution (BSD) were investigated. Air, water, and glass beads were used as the gas, liquid, and solid phases, respectively. Different liquid circulation velocities and different solid loads were applied. The results demonstrate that increasing solid content from 0% to 6% can decrease gas holdup by 50% (due to increased slurry phase viscosity and promotion of bubble coalescence). Also, increasing the liquid circulation rate showed a weak effect on gas holdup, although a slight incremental effect was observed due to the promotion of bubble breakup and the extension of bubble residence time. The gas holdup in counter-current slurry bubble columns (CCSBCs) was predicted using a novel correlation that took into account the combined effects of solid concentration and liquid circulation rate. These findings are crucial for the design and optimization of the three-phase reactors used in industries such as mining and wastewater treatment.

Linking the Pre-Steady-State, Steady-State, and Zero-Order Kinetic Parameters Together for Industrial Applications

There appeared not to have been a way of linking pre-zero-order kinetics to zero-order kinetics so as to garner key kinetic parameters at very high industrial concentrations of the substrate. The objectives were the derivation of equations that can be explored in relating pre-zero-order (pre-steady-state (prss)) to zero-order kinetic parameters (ZOK), such as the Michaelis-Menten constant (KM), maximum velocity of catalysis (Vmax), and specificity constant (SC), to be evaluated. The Vmax for the higher industrial-type concentration of the enzyme (alpha-amylase) was 7812.5 micromoles/l/min, while the KM was 115.1 g/l. The SC obtained by calculation, either by the new equation (Eq. (25b)) or the ratio Vmax:KM, was 67.88 micromoles l/g min. Surprisingly, as compared to the literature, the SC obtained by the new graphical method was 275.4 micromoles l/g min using sub-KM values of substrate concentrations. The prss Vmax and KM were 2348.62 ± 479.94 micromoles l/g min and 7.41 ± 1.77 g/l, respectively. There is a justification for an equation linking PRSS and the ZOK, which can enhance reactor design. The equation linking PRSS to the ZOK kinetic parameters was derived. With the equation, the KM for a very high industrial concentration of the substrate and the enzyme that would have been impossible was made possible. Future studies may focus on assays at high concentrations of the enzyme and sub-KM concentrations of the substrate so as to observe a repeat of higher SC. Note that if the concentration of one enzyme is twice (or more) the concentration of another enzyme of the same kind, the Vmax of the first should be twice the Vmax of the latter given saturating concentrations of the substrate for each enzyme; the parameter that is constant is the catalytic first-order rate constant (kcat); it may be theoretically assumed that the KM can follow the same order as with the Vmax. Apart from a very high concentration of the gelatinized starch that retards the mobility of the enzyme, the spectrophotometer has an upper limit of its power to read color development.

Experimental research on heat transfer characteristics of a two-layer corium pool based on a three-dimensional ellipsoidal lower plenum

To better understand the application of IVR (In-Vessel Retention), extensive experiments have been conducted on the heat transfer characteristics of molten pool. However, most research mainly focuses on hemispherical lower heads, and the research on ellipsoidal lower head suitable for small pressurized water reactors is relatively lacking. In order to provide some reference for the implementation of IVR with ellipsoidal lower head, this paper conducted the experimental study on the heat transfer characteristics of a three-dimensional double-layer molten pool based on the design of a small pressurized water reactor. The test section consists of two parts: ellipsoidal and cylindrical, with a span of 1150 mm and a total height of 700 mm. The molten material is simulated by nitrate mixture (20mol%NaNO3-80mol%KNO3), and electric heating wire is chosen to simulate the oxide layer decay heat. The effects of heating power, oxide layer height and layered partition thickness on heat transfer characteristics of two-layer molten pool under static conditions were studied. The results show that the thermal stratification phenomenon mainly occurs in the lower and middle regions of the oxide layer, with a smaller dimensionless temperature gradient in the upper region; with the similar volumetric power densities, the height of the oxide layer has little effect on the wall heat flux density; the layered partition increases the thermal resistance between the two layers and reduces the upward heat transfer to the ceramic pool. In addition, the heat transfer relationships in the oxide layer, both downward and upward, are fitted for the internal Rayleigh number range of 3.43 × 1012 to 1.54 × 1013.

Design, Scale‐Up, and Dynamic Simulation of a Patented Bayonet Reactor for Commercial Hydrogen Production via Sulfur‐Iodine Water Splitting

ABSTRACTThe sulfuric acid decomposition reactor is a key component of the iodine‐sulfur thermochemical cycle process. The design of the sulfuric acid decomposition reactor requires excellent corrosion resistance and mechanical strength performance. In this work, a patented reactor on a pilot scale was scaled up to an industrial scale. A plant equipment design for an industrial‐scale reactor was performed. Based on an integrated inherent safety design approach, it was determined that the optimal thickness was 110 mm, and the design passed all stress analysis tests. With a minimum targeted hydrogen production rate of 1000 kg/h, the process design yielded a reactor with a diameter of 7 m and a height of 30 m, while silicon carbide was chosen as the construction material. The scaled‐up reactor was dynamically simulated in MATLAB. Simulink demonstrated that both the reactor temperature and product flow rates successfully produced a stable response within 1.8 and 4 h of operation, respectively.

Simulation of solar photocatalytic reactor with immobilized photocatalyst for degradation of pharmaceutical pollutants.

This study focuses on the simulation of a solar photocatalytic reactor with linear parabolic reflectors and continuous fluid flow. The simulation approach was initially validated against experimental data reported by Miranda-Garcia et al. Catal Today 151:107-113 (2010), yielding a high degree of accuracy of approximately 0.99%. In this article, the effect of light intensity, Reynolds number, and fluid residence time on the performance of a photoreactor system using titanium dioxide catalyst and ibuprofen pollutant has been investigated. The results show that the intensity of light intensity has an effect of up to 29% on the decomposition of pollutant. With the increase of radiation intensity, the removal of pollutants reached from 85.5% to 99.46%. It has been demonstrated that higher flow turbulence significantly impacts removal efficiency, achieving rates of up to 71%. Moreover, enhancing the fluid's residence time through implementing a recirculating flow within the photoreactor has resulted in a 13% enhancement in removal efficiency. These results can be an important guide for optimizing the design of photocatalytic reactors. By adjusting the examined parameters, it is possible to obtain a higher efficiency in the removal of pollutants, which will be very effective in the scaling and industrial design of solar reactors.

Recent developments in photo-fermentative hydrogen evolution: Fundamental biochemistry and influencing factors a review.

The global shift towards renewable energy sources highlights the urgent need for sustainable hydrogen production, with photo-fermentative hydrogen evolution (PFHP) emerging as a promising solution. This review addresses the challenges and opportunities in optimizing PFHP, specifically the role of photosynthetic bacteria (PBS) in utilizing sunlight for hydrogen production. We focus on the key factors influencing PFHP, including light intensity, reactor design, substrate selection, carbon-to-nitrogen ratio, metal ions, temperature, pH, charge transfer and genetic engineering. Additionally, we explore recent advances in techniques such as immobilization, nanoparticles, biochar, and co-culturing to enhance hydrogen production efficiency. By synthesizing the latest research, this review provides new insights into improving PFHP processes, offering strategies for more efficient biohydrogen production. This work contributes to the development of sustainable hydrogen production technologies, advancing the potential for biohydrogen as a clean energy source.

Modeling of a Continuous Stirred Tank Reactor and Controller Design Using LMI Approaches

Modeling of a Continuous Stirred Tank Reactor and Controller Design Using LMI Approaches

Advances in plastic to fuel conversion: reactor design, operational optimization, and machine learning integration

Plastic waste management is a pressing global problem that requires sustainable solutions to mitigate environmental harm.

Continuous flow synthesis of metal nanowires: protocols, engineering aspects of scale-up and applications.

This review comprehensively covers the translation from batch to continuous flow synthesis of metal nanowires (i.e., silver, copper, gold, and platinum nanowires) and their diverse applications across various sectors. Metal nanowires have attracted significant attention owing to their versatility and feasibility for large-scale synthesis. The efficacy of flow chemistry in nanomaterial synthesis has been extensively demonstrated over the past few decades. Continuous flow synthesis offers scalability, high throughput screening, and robust and reproducible synthesis procedures, making it a promising technology. Silver nanowires, widely used in flexible electronics, transparent conductive films, and sensors, have benefited from advancements in continuous flow synthesis aimed at achieving high aspect ratios and uniform diameters, though challenges in preventing agglomeration during large-scale production remain. Copper nanowires, considered as a cost-effective alternative to silver nanowires for conductive materials, have benefited from continuous flow synthesis methods that minimize oxidation and enhance stability, yet scaling up these processes requires precise control of reducing environments and copper ion concentration. A critical evaluation of various metal nanowire ink formulations is conducted, aiming to identify formulations that exhibit superior properties with lower metal solid content. This study delves into the intricacies of continuous flow synthesis methods for metal nanowires, emphasizing the exploration of engineering considerations essential for the design of continuous flow reactors. Furthermore, challenges associated with large-scale synthesis are addressed, highlighting the process-related issues.

Rational design of stainless steel self-catalytic reactors for CO2 methanation: extending from metal powder to 3D-printed reactors

A design strategy that optimizes surface functionalization from the metal powder precursor to the final 3D-printed self-catalytic reactors is proposed.

Mass and heat transfer at spiral tube internal used as a heat exchanger and catalyst support in a continuous bubble column reactor

ABSTRACT Slurry bubble columns find extensive applications in three-phase reactions, including biological wastewater treatment, fermentation, and hydrotreating, among others. Despite their merits, these reactors suffer from drawbacks such as high back mixing and challenges in product-catalyst separation. This study introduces a novel approach to address these issues by employing a horizontally placed spiral tube within the column, serving as both a catalyst support and a heat exchanger. The study investigates the impact of two-phase flow on mass transfer at the outer surface of the spiral tube using the limiting current based electrochemical technique. The experimental setup involves varying spiral tube diameter and pitch, as well as distances between successive spiral tubes. The results showed that the mass transfer coefficient increases with increasing superficial gas and solution velocities but decreases with increasing spiral tube diameter and pitch. An array of three separated horizontal spiral tubes was also tested, and the mass transfer coefficient was found to be slightly lower than that of a single spiral tube by an amount ranged from 4 to 19%. The study provides valuable insights into optimizing reactor design for improved efficiency, offering a potential solution to challenges in slurry bubble column reactors.

CFD-Based Determination of Optimal Design and Operating Conditions of a Fermentation Reactor Using Bayesian Optimization.

The efficiency of fermentation reactors is significantly impacted by gas dispersion and concentration distribution, which are influenced by the reactor's design and operating conditions. As the process scales up, optimizing these parameters becomes crucial due to the pronounced concentration gradients that can arise. This study integrates the kinetics of the fermentation process with hydrodynamic analysis using Bayesian optimization to efficiently determine the optimal reactor design and operating conditions. By utilizing computational fluid dynamics (CFD) simulations, the study provides a comprehensive assessment of distributions ranging from gas supply to cell growth. The results demonstrate that a combination of wide baffle width, narrow impeller gap, slow gas flow rate, and high agitation speed significantly enhances reactor performance by improving gas distribution and minimizing stagnant zones. These findings underscore the importance of considering both kinetic and hydrodynamic factors to achieve more precise and scalable fermentation processes, offering valuable insights for industrial applications.

Аварія на Ленінградській АЕС (1975) у контексті передумов Чорнобиля

The purpose of the study is to reconstruct and analyze a set of issues related to the accident at the Leningrad NPP in the context of clarifying the prerequisites of the Chernobyl disaster. Our study examines issues related to the accident at Unit 1 of the Leningrad NPP (LNPP) in 1975. This is the largest accident in the «pre-Chernobyl» period, a precursor to Chernobyl. This topic remains ignored in domestic historical scientific literature. The article by the co-authors, based on published sources, mostly memoirs, attempts to highlight a number of aspects related to the accident at the Leningrad NPP. The research methodology is based on a combination of general scientific (analysis, synthesis, generalization) and special historical (historical-genetic, historical-typological, historical-comparative) methods with the principles of historicism, systematicity, scientificity and verification. The scientific novelty of the work lies in the fact that the development of aspects related to the problems of the history of nuclear energy in the USSR is almost not studied in domestic historical science. In this regard, in particular, the study of the prehistory and prerequisites of the Chernobyl disaster is important. Conclusions. It was established that the design of the RBMK-1000 reactor and other technological systems of the power unit were far from perfect. It has been established that the design of the RBMK-1000 reactor and other technological systems of the power unit were far from perfect. It is shown that the process of improving the reactor installation took place during installation and operation, including through various experiments. The available sources to a certain extent make it possible to reconstruct the causes, prerequisites, nature and circumstances of this accident. First of all, it is found that the accident revealed serious shortcomings of the RBMK-1000 reactor. The article highlights the socio-economic and human factors of the accident. In particular, it is shown that at Soviet nuclear power plants the policy of prioritizing the plan for generating electricity over the requirements of regulatory documents for the safe operation of the reactor dominated. A similar phenomenon occurred at the Chernobyl Nuclear Power Plant (ChNPP). Based on the sources, it was possible to clarify the key role in creating the accident of a certain person, namely the senior reactor control engineer Mikhail Karrask. Our study also pays attention to covering the work of the special commission to investigate the accident. In this regard, it was particularly important to understand whether information about the nature of the accident and the commission's recommendations on improving the operation of the RBMK-1000 reactor reached the attention of the personnel of other nuclear power plants, primarily the Chernobyl NPP.

ANALYSIS OF THE STRUCTURE OF INTERFERENCE COATINGS FOR THE OPTIMIZATION OF THE PARAMETERS OF NARROWBAND OPTICAL FILTERS

To monitor the parameters of semiconductor layers deposited from solid solutions of A3B5 compounds during the epitaxy, optical control methods are used. The choice of optical monitoring methods is determined by the reactor design, which requires non-contact, fast, and precise measuring of wafer surface parameters. During the growth of epitaxial layers, the deposition of semiconductor compounds causes changes in the optical parameters of the wafer surface. To ensure precise measurements, it is essential to monitor these parameters within a narrow spectral range. In electro-optical monitoring systems, narrowband interference filters are used to select the desired spectrum. However, this type of filters is sensitive to several factors, such as environmental conditions, aging of the coating, and the angle of incidence. As a result, the manufacturing of narrowband optical filters with stable and precisely controlled optical characteristics presents a complex challenge. This article analyzes the impact of various factors on the optical characteristics of interference coatings. Quantitative analysis of these shows that shift of the selected spectral band with central wavelength λmax can approach or even exceed the full width at half maximum (FWHM). These changes in the optical characteristics of narrowband filters lead to a decrease in the accuracy required for optical monitoring during epitaxial processes, which leads to inaccuracies in measurements. The results of this analysis will guide the optimization of thin-film structures used in narrowband optical filters. The study of the shift in the selected band also enables, within certain limits, controlled changes to λmax or the compensation of its shift its shift during regular factor variations. Ultimately, it enables to take these changes into account when designing electro-optical systems for monitoring the epitaxial growth of semiconductor heterostructures, which increases the accuracy and stability of optical measurements in the required accuracy range.

Novel Study of Reaction Kinetics and Mass Transfer in Bioreactor Modelling: Prediction of Bioethanol Fermentation Performance by Saccharomyces cerevisiae on Continuous Fixed Bed Biofilm Plug Flow Reactor

Bioethanol implementation as a renewable fuel has yielded economic, social, and environmental benefits, including reduced fossil fuel consumption, enhanced energy diversity and supply security, lower greenhouse gas emissions, and support for agricultural communities. These impacts underscore the importance of advancing innovation and optimizing processes to increase bioethanol production. Therefore, basic knowledge of chemical engineering in bioethanol fermentation is important to be learnt as a preliminary study, such as reaction kinetics and transport phenomena. This work studies the reaction kinetics and mass transfer in continuous fixed bed biofilm plug flow reactor modelling to predict anaerobic Saccharomyces cerevisiae fermentation performance, which is still not studied comprehensively. This modelling provides an overview of the influence of various independent variables, namely temperature, initial substrate concentration, cell concentration, superficial flow rate, reactor diameter, and solid particle diameter on various dependent variables, namely final product concentration, residence time, reactor length, reactor volume, product productivity, and pressure drop. The most sensitive parameters related to product productivity are temperature and cell concentration, so in its implementation, the temperature must be controlled at its optimum temperature, and the inoculum must be prepared with high cell concentration. For the next study, it is recommended to study the optimization of reactor design and operation (i.e. the pumping system, cooling system, and pH control of the reactor) and the implementation of the reactor on the plant scale. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Numerical analysis of the self-sustaining traveling wave of nuclear fission propagated by epithermal neutrons in uranium dicarbide medium

This study investigates the self-sustaining traveling wave of nuclear fission in a uranium dicarbide medium by numerically solving a system of partial differential equations. The primary focus is on the neutron diffusion equation and nuclide balance equations, which are crucial for understanding the behavior of fission waves. By solving these equations, we aim to determine the propagation characteristics and assess the stability of nuclear fission waves in uranium dicarbide. Numerical analysis provides significant insights into the dynamics of neutron distribution and nuclide evolution, enhancing our understanding of the underlying physical processes and their implications for traveling wave reactor design.