Different Types Of Reactors Research Articles

A review on solar methane reforming systems for hydrogen production

Hydrogen energy is a promising alternative to fossil fuels. Solar hydrogen production through steam and carbon dioxide methane reforming is one of the sustainable and environmentally friendly methods for supplying hydrogen. This review will focus on steam and dry methane reforming. A section on methane reforming catalysts is considered to review different types of catalysts, including noble metals, non-noble metals, and Ni-based catalysts. The catalysts section will focus on the activity and stability of the catalysts. Methane reforming using solar energy is the next main section of this review and will be discussed in detail in different types of reactors, including tubular, volumetric, and membrane reactors. Sorption-enhanced steam methane reforming using solar energy will also be discussed in detail. It should be mentioned that the highly efficient methane reforming systems will be investigated. Finally, some conclusions and future trends will be proposed in the solar methane reforming field.

Energy from nuclear fission

The physics of nuclear fission will be briefly illustrated, from the basic mechanism behind this phenomenon to the relevant physical quantities like nuclear cross sections, neutron flux and reaction products, together with the accompanying phenomenon of neutron capture and its role in determining how the fuel transforms in a nuclear reactor. The basic concepts underlying the operation of different types of nuclear reactors will be illustrated, along with the concept of fuel cycle. The aspects of radioactive waste, fuel resources and safety will also be briefly illustrated.

Vanquishing the computational cost of passive gamma emission tomography simulations leveraging physics-aware reduced order modeling

Passive Gamma Emission Tomography (PGET) has been developed by the International Atomic Energy Agency to directly image the spatial distribution of individual fuel pins in a spent nuclear fuel assembly and determine potential diversion. The analysis and interpretation of PGET measurements rely on the availability of comprehensive datasets. Experimental data are expensive and limited, so Monte Carlo simulations are used to augment them. However, Monte Carlo simulations have a high computational cost to simulate the 360 angular views of the tomography. Similar challenges pervade numerical science. With the aim to create a large dataset of PGET simulated scenarios, we addressed the computational cost of Monte Carlo simulations by developing a physics-aware reduced order modeling approach. This approach combines a small subset of the 360 angular views (limited views approach) with a computationally inexpensive proxy solution (real-time forward model) that brings the essence of the physics to obtain a real-time high-fidelity solution at all angular views but at a fraction of the computational cost. The method’s ability to reconstruct 360 views with accuracy from a limited set of angular views is demonstrated by testing its performance for different types of reactor fuel assemblies.

A correction method for the incomplete dissociation of sulfuric acid in the Villermaux-Dushman reaction system

The Villermaux-Dushman reaction system is the most popular method for characterizing the micromixing performance of various reactors, which traditionally uses sulfuric acid as the proton source. However, the accurate initial proton concentration (IPC) in this system is hardly accessible owing to the two-step dissociation of the sulfuric acid, resulting in the inaccuracy of the segregation index (XS). In this work, a novel strategy was proposed to correct XS obtained by sulfuric acid as the proton resource via comparing with that obtained by perchloric acid. Under the same theoretical IPC, the micromixing experiments using sulfuric acid and perchloric acid were conducted in different types of reactors, respectively. The conclusions were consistent that an increase of approximately 1.3 times in XS was observed using perchloric acid relative to sulfuric acid. Hence, 1.3 could be considered as the correction coefficient to acquire the exact XS when sulfuric acid, with the concentration ranges from 0.05 to 0.195 mol/L, was used as the proton source. The deviation between the corrected and experimental XS was within ±15%. Overall, this work provides a secure and feasible strategy to accurately evaluate the micromixing performance.

Reactor Structure for the Decomposition of ADN-Based Monopropellant

Ammonia dinitramide (ADN)-based liquid monopropellants are considered to be environmentally friendly alternatives to the toxic and carcinogenic hydrazine-based propellants. Hence, Space Solutions Co., Ltd. is developing a 1N ADN-based liquid monopropellant thruster by conducting a combustion performance in different types of reactors. Various parameters, such as preheating temperature and the size of thermal and catalyst beds, were examined. The results showed that the decomposition of the propellant in a Pt-LHA catalyst bed, which was used in the Type-1 reactor, resulted in insufficient combustion at low preheating temperatures. Furthermore, increasing the preheating temperature led to partial reaction of the propellant, but resulted in low combustion efficiency due to disintegration of the catalyst. However, when a thermal bed (STS ball) was used in addition to the catalyst bed (Pt-LHA) in the Type-2 and Type-3 reactors, the combustion efficiency was improved, with a minimal pressure drop of 0.2 bar. It was also confirmed that the catalyst was not damaged even after repeated operations. In conclusion, this study suggests that the propellant needs to vaporize before decomposing on the catalyst bed to achieve optimal combustion efficiency.

Techno‐economic comparison of different reactor types used in the manufacture of fructooligosaccharides from sucrose

AbstractFructooligosaccharides, a low‐calorie alternative sweetener with prebiotic effects, can be synthesized from sucrose via enzymatic reactions. Recently, methods for producing novel fructooligosaccharides using free and immobilized Bacillus licheniformis RN‐01 levansucrase were developed at the laboratory scale. However, there was a need to apply engineering knowledge in production process design and scale‐up to develop and evaluate the feasibility of this technology in the industrial scale. In this paper, three different types of reactors for fructooligosaccharides production using B. licheniformis RN‐01 levansucrase were compared in terms of technical and economic aspects. The previously collected experimental data, including enzyme activities, immobilization yields, product yields, and material balances, were used to estimate the capital and operating costs of fructooligosaccharides production using (a) immobilized enzyme in a stirred‐tank reactor, (b) immobilized enzyme in a packed‐bed reactor, and (c) free enzyme in a stirred‐tank reactor. The technical issues in reactor design and operation were also evaluated. The results showed that, in terms of minimum product selling prices, the process using immobilized enzyme had more economic advantages than the process using free enzyme because the cost savings from enzyme purchasing could compensate the additional equipment and chemical costs in the enzyme immobilization process. The results could be a guideline for selecting suitable reactor types for fructooligosaccharides production and provide directions for further reactor design and development.

Performance and microbial characteristics of completely autotrophic nitrogen removal over nitrite process in different types of reactors

There are various types of reactors for completely autotrophic nitrogen removal over nitrite (CANON) process, but the advantages and disadvantages of different types of reactors and their scope of application still need to be studied. In this paper, high-throughput sequencing technology was used to analyze the microbial characteristics of four CANON reactors with similar and stable influent water quality conditions, and the applicable scenarios of different types of CANON reactors was clarified. At the gene level, the proportions of aerobic ammonia oxidizing bacteria (AerAOB), anaerobic ammonia oxidation bacteria (AnAOB) and denitrifying bacteria in a flocculent sludge sequencing batch reactor (FSBR), a membrane bioreactor (MBR), a biological aerated filter (BAF) and a granular sludge sequencing batch reactor (GSBR) were 16.88 %, 3.49 %, 19.36 % and 29.67 %; 9.51 %, 4.72 %, 5 % and 27.75 %; 7.12 %, 11.5 %, 6.81 % and 13.6 %. The results showed that FSBR was low nitrogen removal load and low stability in practical application. MBR can treat different concentrations of ammonia nitrogen wastewater by controlling the influent load. BAF can treat ammonia nitrogen wastewater with moderate influent load. GSBR has high removal load and can treat high ammonia nitrogen wastewater.

Removal of CO2 from Biogas during Mineral Carbonation with Waste Materials

Biogas represents a source of renewable energy that could provide a replacement for fossil fuels to meet the increasing demand for energy. The upgrading of biogas through the removal of CO2 to a content of 95-97% of CH4 is necessary to increase its calorific value. This review focuses on biogas upgrading technologies using wastes or residues that enable the performing of mineral carbonation. In this research, we analyzed a natural biogas or synthetic one with a content of about (40-50%) of carbon dioxide. The chemical absorption is also briefly described in this study, due to its being the first step in innovative absorption and regeneration processes using mineral carbonization. Wastes with high calcium contents, i.e., ashes, steel-making slags, and stabilized wastewater anaerobic sludge, were considered for direct carbonization, taking into account the leaching of particles from carbonated wastes/residues. Moreover, the different types of reactors used for mineral carbonation have been described. The presented technological solutions are easy to use and economical, and some of them also take into account the regeneration of reagents. However, in the context of their direct use in biogas plants, it is necessary to consider the availability of wastes and residues.

Uncertainty analysis of the control rod drop based on the adaptive collocation stochastic perturbation method

There are many uncertain factors to affect the control rod drop from its design and manufacture to the chain reaction in the reactor. They have to be considered in the simulation to realistically predict the dynamic behavior of control rod drop. Different from the previous method by using the nominal and extreme values of the uncertain factors, a statistical method is applied in this paper to analyze them in the process of the control rod drop. The uncertain factors obey uniform distribution, based on which a fifth-order adaptive collocation stochastic perturbation (ACSP) method is established in this paper, which is featured with simple format, high precision, and high calculation efficiency. The mean and standard deviation of the responses (such as the final time of the control rod drop) in two different types of reactors are calculated by using the ACSP method. On this basis, the response intervals and corresponding probabilities of the control rod drop are obtained. Besides, influences of each random variable on the responses are analyzed by the sensitivity analysis. In addition, the linear correlation degree and correlation between the two are discussed through the correlation coefficient of random variables and the responses. The uncertainty analysis of control rod drop in this paper not only provides a relatively strong theoretical support for scientifically dealing with uncertain factors, but also offers specific help for the optimal design of control rod assembly.

A Comparative Analysis of Waste Biomass Pyrolysis in Py-GC-MS and Fixed-Bed Reactors

Pyrolysis is one of the most popular methods for the thermal conversion of biomass-derived materials, which can be applied to produce valuable products such as biochar, bio-oil, and pyrolysis gas. However, this does not change the need for more precise data on the products obtained from such processes under different conditions, using different types of reactors or types of biomass material. Pyrolysis products can have a high energy value and have been extensively studied. In the presented research, three potential energy feedstocks from waste biomass, wheat cereal straw (CS), tobacco waste (TW), and furniture waste (FW) were comprehensively evaluated in terms of product yields, as well as the chemical composition of the volatile products of the pyrolysis process using the pyrolysis–gas chromatography–mass spectrometry technique and the chemical distribution of the products obtained under fixed-bed pyrolysis conditions. The obtained results were compared to data from the literature, which provided thorough information on the pyrolysis of biomass materials in diverse systems. The research identified the primary elements of the liquid fraction, such as N-compounds, furans, phenols, benzene, PAHs, aldehyde-ketone-alcohol, and organic acids, which were the main constituents of the liquid fraction, and the concentration of non-condensable components of gaseous products. The research discussed in this article provides a comprehensive approach to the thermal conversion of biomass materials, which, depending on their origin, processing conditions, and methodologies, can be utilised for more than only energy production.

Prospect of Direct Dimethyl Ether Production from CO2: Reactor Design Development

The increasing emissions of carbon dioxide (CO2) and volatile hydrocarbons via burning of fossil fuels result in a significant amount of global warming and air pollution. With the concern over the impact of fossil fuel to the environment, the interest in alternative fuel production from the CO2 generated through utilization of new technologies has risen rapidly. Several clean alternative fuels, including dimethyl ether (DME) have been investigated for a more sustainable and greener environment. DME has a high cetane number but produces much lower NOx emission upon combustion. DME is typically synthesized using syngas based on conventional indirect DME route, where the process begins with conversion of syngas into methanol and subsequently dehydrated to DME in separate units. Recently, a direct single-step route to produce DME through dehydrogenation of CO2 and dehydration of methanol by utilising a novel bifunctional catalyst has been investigated. In direct DME, the dehydrogenation and dehydration occur simultaneously in a single reactor, which eliminate the need for a methanol production plant. However, the use of conventional fixed-bed reactor (FBR) for the direct DME synthesis causes many challenges including catalyst deactivation, where water appears in the reaction area, limiting the conversion of CO2 reactants into DME and consequently, the DME yield. It is also essential to manage the exothermic heat generated from the catalyst for better DME yield. In order to overcome these hurdles, several types of reactors have been proposed such as fluidized bed reactor, slurry reactor, microreactor and catalytic membrane reactor. In this paper, different types of reactors are first discussed and its applications related to the direct DME production from CO2 are highlighted. Finally, the challenges and difficulties of reactor development are addressed and future direction is outlined.

Distribution of hydrogen isotope in the soil around the Qinshan Nuclear Power Plant

When a different types of reactor are operating at the same area and the same period of time, released radionuclides are hard to follow in the environment. In general, isotopic techniques can be used for source localization. To obtain the distribution of hydrogen isotope in soil, eight sampling points were selected along the local dominant wind direction with different distances away from Qinshan Nuclear Power Plant, and soil samples at different depths (0–2, 2–5, 5–10, 10–20, 20–30 cm) were collected in December 2019 and December 2020, respectively. The concentrations of hydrogen isotopes were measured in the soil samples at different depth. The spatial distribution of tritium and deuterium in the surface soil was related to soil properties and the distance from the nuclear power plant. It was found that tritium and deuterium are generally enriched in the upper layer. Determination of the deuterium concentration in the environment may be a new way to trace the released tritium from the reactors.

Advancements in droplet reactor systems represent new opportunities in chemical reactor engineering: A perspective

AbstractTraditional chemical reactors, such as batch reactors, continuous reactors, and semi‐batch reactors, have been extensively studied and frequently act as central components of modern chemical plants. Recently, various advances in reaction times, surface‐to‐volume ratios, required amounts of reagents, and throughput have led to new directions in the design of miniaturized chemical reactors. In this Perspective, we provide an overview of the progress from traditional to miniaturized chemical reactors by summarizing the characteristics and applications of different types of reactors. Furthermore, we compare classical chemical reactors and miniaturized droplet reactors to highlight advancements in the design of droplet reactor systems based on open functional surfaces. Finally, we provide an outlook on the research directions of miniaturized droplet reactors.

Post irradiation examination of a uranium-zirconium hydride TRIGA fuel element

Low-enriched (LEU) U-ZrH fuel, with a235U content less than 20% of the total uranium, is being evaluated for possible use in different types of reactors, including space nuclear systems, light water reactors (LWRs) and micro-reactors. As a result, it is beneficial to better understand the macrostructural and microstructural changes that occur in this fuel during irradiation. This paper reports the results of the post irradiation examination of an LEU U-ZrH fuel element (30 wt.% U, <20% 235U) using neutron radiography, precision gamma scanning, chemical analysis, optical metallography and scanning electron microscopy combined with energy dispersive spectroscopy and wavelength dispersive spectroscopy, where the fuel element was irradiated in a Training, Research, Isotope, General Atomics (TRIGA) reactor. Results of microstructural characterization indicated some dehydriding and cracking of the U-ZrH fuel occurred during irradiation; an axial and radial burnup gradient existed in the fuel during irradiation, as measured by gamma scanning and chemical analysis; negligible microstructural changes transpired during irradiation, based on comparison of irradiated and as-fabricated U-ZrH fuel microstructures; and, negligible, fission product-rich, phases could be resolved in a U-ZrH fuel that was irradiated to a calculated 20% depletion of 235U.

Just Suspended Speed Simulation in Torus Reactor Using Multiple Non-Linear Regression Model

In the chemical and water treatment industries, it is necessary to achieve maximum contact between the solid and liquid phase, thus promoting the mass and heat transfer, to obtain a homogeneous solution. Increasing stirring speed is the most recommended solution in different types of reactors: stirred tank, column, and tubular. However, this inadvertently increases the energy consumption of the industry. Determination of the minimum speed, labeled the just suspended speed (Njs) and crucial to attaining homogeneity, has been widely investigated. Numerous studies have been carried out to assess formulas for determining the solid particle speed in various reactor types. Given the limitations of the existing formulations based on a generalization of a unique equation for computing Njs for all soil classifications, it appears that most formulas can only approximate complex phenomena that depend on several parameters. A novel formula was developed, and the results given in this paper demonstrate the effectiveness of generating significant uncertainties for the estimation of Njs. The purpose of this study was the elaboration of experiment-based data-driven formulas to calculate Njs for different particle size classes. Nonlinear multiple regression (MNLR) models were used to generate the new formulas. The gradient descent optimization algorithm was employed to solve the hyperparameters of each novel equation, utilizing supervised learning. A comparison of the data indicated that the unique formulas presented in this study outperformed empirical formulas and provide a useful means for lowering energy consumption, while increasing the heat and mass transfer in torus type reactors.

TRACES OF 14C EMISSIONS FOR THE OPERATION PERIOD OF TWO UKRAINIAN NPPS: RIVNE AND CHORNOBYL

ABSTRACTThe aim of this study was a comparative retrospective assessment of radiocarbon (14C) as a tracer, caused by operational emissions of Rivne and Chornobyl nuclear power plants (NPPs), which are equipped with different types of nuclear reactors. For this purpose, 14C was studied in annual tree rings of pine taken at a distance of 1.5 km southwest of the Rivne NPP and at a distance of 3.5 km west-northwest of the Chornobyl NPP, near the Yaniv railway station. As a background, we use the 14C in air data (Hua et al. 2013), which we continue for time interval 2009–2020 with our experimental data for pine tree rings. Tree rings were also collected in a rural area 60 km west of Kyiv, where industrial impact, in our opinion, is absent. 14C in wood samples was determined using the conventional method based on liquid scintillation counting. It was found that the 14C excess in the annual tree-ring samples of pine near the Chornobyl NPP during the observed operation period (1984–2000) was 3.0–13.0 pMC, except for the 1986, the year of the Chornobyl accident, when the 14C value rose sharply to 182.7 pMC (14C excess 62 pMC). After 2000, the content of 14C in the air near the Chornobyl nuclear power plant did not exceed the background values within the uncertainty of the measured data. The concentration of 14C in the samples of annual tree rings of pine near the Rivne NPP for the observation period (1986–2019) corresponded to the background levels within the uncertainty of the measured data. The study of environmental traces of 14C emissions from two NPPs equipped with different types of reactors showed significantly lower emissions of Rivne NPP with VVER compared with emissions from Chornobyl NPP with RBMK reactors.

Study on Biological Pathway of Carbon Dioxide Methanation Based on Microbial Electrolysis Cell

Realization of CO2 resource utilization is the main development direction of CO2 reduction. The CO2 methanation technology based on microbial electrolysis cell (MEC) has the characteristics of ambient temperature and pressure, green and low-carbon, which meets the need of low-carbon energy transition. However, the lack of the system such as the change of applied voltage and the reactor amplification will affect the methane production efficiency. In this research, the efficiency of methane production with different applied voltages and different types of reactors was carried out. The results were concluded that the maximum methane production rate of the H-type two-chamber microbial electrolysis cells (MECs) at an applied voltage of 0.8 V was obtained to be 1.15 times higher than that of 0.5 V; under the same conditions of inoculated sludge, the reactor was amplified 2.5 times and the cumulative amount of methane production was 1.04 times higher than the original. This research can provide a theoretical basis and technical reference for the early industrial application of CO2 methanation technology based on MEC.

Performance evaluation of oscillatory baffle Bunsen reactor in iodine sulfur thermochemical process for hydrogen production

<abstract> <p>Hydrogen is an environmentally attractive transportation fuel that can replace fossil fuels. The iodine-sulfur (I-S) thermo-chemical process involves three reaction steps. The Bunsen reaction is one of the main reaction steps of I-S process and plays an important role in defining overall process efficiency. Different types of reactors are being studied, including the oscillatory baffle Bunsen reactor. The reactor selection is based on process intensification and process integration, i.e., reaction and separation in the single equipment. Simulations are performed for two-dimensional cases by solving incompressible Navier-Stokes equations along with continuity equation, the geometry chosen is of single section in the column and diameter of 50 mm and baffle spacing of 50, 75,100 mm i.e. 1, 1.5 and 2 times the diameter of column and baffle free area 22%. The residence time distribution experiments are carried out in a metallic reactor with NaCl as a tracer operated at different frequencies, amplitudes and flow rates. D/uL is evaluated from experimental curves. The power per unit mass is compared for oscillatory baffled column and stirred tank for a semi-batch process. From the numerical simulations, good eddy interactions are present at higher frequencies and amplitudes and at a baffle spacing of 1.5 times the diameter of the column. Residence time distribution analysis gives a lower dispersion number at medium frequencies and higher amplitudes with constant flow rate. If the flow rates are high, then it is better to operate at higher frequencies and amplitudes to achieve plug flow behavior. Power per unit mass is less for oscillatory baffle column compared to the stirred tank of given configuration. With better mixing performance and less power per unit volume, the oscillatory baffle column is a good alternative to other columns.</p> </abstract>

Analytical solution of the multigroup neutron diffusion equation coupled with an iterative method

Many numerical methods are being used to solve the multigroup neutron diffusion equation for different types of nuclear reactors. These methods solve this equation quite accurately and determine the neutron flux and power distribution in the reactor as well as the eigenvalue of the reactor core. In this paper, we are proposing the integration of an analytical solution with an iterative method to determine the neutron flux distribution in the reactor and the effective eigenvalue. To do this, we solve the one-dimensional neutron diffusion equation for two energy groups, where the nuclear parameters are uniform in both nuclear fuel and reflector regions. The eigenvalue will be determined from the analytical solution using the power method iteratively until reaching convergence in both flux and eigenvalue. The results obtained in this paper are compared with results obtained from numerical methods used to validate the proposed method.

Bi-Directional Converter System for Light Load by Heterogeneous Combined Type Reactor

In this paper, we propose a new type of smoothing reactor using different types of reactors with different magnetic flux saturation to construct a DC-DC converter with low current ripple under the light load of the bidirectional DC-DC converter. Reduction of current ripple at light load in the limited hybrid reactor can greatly reduce the inrush current ripple of DC-Grid at light load, which is a weakness of existing bidirectional DC-DC converters and is considered to contribute to DC-Grid stabilization. Experiments were conducted to prove the feasibility of the proposed system and hybrid reactor.