Kind Of Reactor Research Articles

Ethanol production from sugarcane bagasse by modified PDMS membrane in a membrane bioreactor: pervaporation technique

AbstractBACKGROUNDBioethanol is considered a highly promising alternative to fossil fuels due to its derivation from renewable sources. Reducing the disadvantages of conventional fermentation requires removing the product from the fermentation broth after its formation. Therefore, coupling the membrane separation with a biological process in a single unit leads a reduction of substrate and product inhibitions.RESULTSIn this work, bioethanol production was investigated in a membrane bioreactor (MBR) with sugarcane bagasse (lignocellulose waste) as a renewable source by the sulfuric acid hydrolysis process. Firstly, the optimum conditions to produce the maximum amount of sugar by acid hydrolysis were determined. Second, the membrane bioreactor and pervaporation unit equipped with poly(dimethyl siloxane) carbon nanotube/Tetrazole membrane (PDMS‐CNT/Tetrazole) was fabricated. Third, bioethanol production in a conventional batch reactor (CBR) and the novel MBR was implemented. The outcomes of the two kinds of reactors were then compared. The results illustrated that the optimum conditions for acid hydrolysis are at a temperature of 199.4 °C, an operation time of 30.77 min, and an acid concentration of 1.12%. The obtained data shows that the ethanol production in MBR was increased by 103.6% over conventional fermentation. Furthermore, the pervaporated ethanol concentration was higher than that of the broth because of the high membrane selectivity, where a maximum ethanol concentration of 165.7 g L−1 in the cold trap was achieved.CONCLUSIONFinally, the results illustrate that the MBR can decrease the cell density growth rate and dominate any substrate and product inhibitions, while keeping process productivity for ethanol quite high. © 2024 Society of Chemical Industry (SCI).

An innovative pillow-plate reactor for the synthesis of methanol from biogas: A simulation study

This work investigates the performances of a pillow-plate heat exchanger utilized as reactor for small-scale methanol synthesis. When downscaled, multi-tubular packed bed reactors are complicated to use since they undergo rapid losses in catalyst activity. A possible pathway to improve the unit performances is to diminish the tubes diameter and number. As this kind of reactors is governed by convective heat transfer, though, the use of long tubes is required to keep the mixture velocity high. This leads to the use of very long reactors, which cannot be easily realized with traditional designs. In order to tackle this issue, we propose the utilization of an innovative design, the pillow-plate reactor, increasing heat and mass transfer and the unit compactness. The study compares the performances of a packed-bed and a pillow-plate reactor through temperature profiles and methanol productivity at varying reactor lengths (1 – 6 m). It is proved that the pillow-plate unit, unlike the multi-tubular one, well manages scale reduction: when 1 m long reactors are employed, the outlet methanol fraction is close to equilibrium (5.8% vs. 4.9% for packed beds) and the hot-spots are well controlled (537 K vs. 557 K for tubular reactors). Moreover, it is also shown that the distance of metal layers in the pillow arrangement remarkably influences heat exchange, which is very effective for close layers, with a hot-spot of 518 K with a 3 mm gap, and much worse for the 12 mm design (552 K).

Impact of CO2 atmosphere on coal pyrolysis in indirectly heated fixed bed with internals

To clarify how CO2 affects pyrolysis characteristics in reactor with internals, pyrolysis of Yulin coal under N2 (inert) and CO2 (active) atmospheres is performed in fixed-bed reactors for two kinds of pyrolysis, i.e., with and without internals.CO2 exhibits different impact on tar yield for two types of pyrolysis, i.e., raising tar yield for pyrolysis in reactor without internals but lowering tar yield for that with internals. Tar yield pyrolysis under CO2 atmosphere is 6.31 wt% with internals, which is still higher 15.97% than that without internals at 1000 °C. In addition, CO2 atmosphere can produce more CO, high BET surface area char and high-quality of tar with more light tar (<C10), but less char, H2 and CH4 for both types of pyrolysis. The different impact of CO2 may be ascribed to the various flow routes for two kinds of reactors, and the extent of CO2-inclusive reactions, such as CO2-char gasification and reverse water gas shift (RWGS), is weakened by the adoption of internals due to occurring at lower temperatures and shorter residence time.

Volatile organic compounds degradation by nonthermal plasma: a review.

Volatile organic compounds (VOCs) have posed a severe threat on both ecosystem and human health which thus have gained much attention in recent years. Nonthermal plasma (NTP) as an alternative to traditional methods has been employed to degrade VOC in the atmosphere and wastewater for its high removal efficiency (up to 100%), mild operating conditions, and environmental friendliness. This review outlined the principles of NTP production and the applications on VOC removal in different kinds of reactors, like single/double dielectric barrier discharge, surface discharge, and gliding arc discharge reactors. The combination of NTP with catalysts/oxidants was also applied for VOC degradation to further promote the energy efficiency. Further, detailed explanations were given of the effect of various important factors including input/reactor/external conditions on VOC degradation performance. The reactive species (e.g., high-energy electrons, HO·, O·, N2+, Ar+, O3, H2O2) generated in NTP discharge process have played crucial roles in decomposing VOC molecules; therefore, their variation under different parameter conditions along with the reaction mechanisms involved in these NTP technologies was emphatically explained. Finally, a conclusion of the NTP technologies was presented, and special attention was paid to future challenges for NTP technologies in VOC treatment to stimulate the advances in this topic.

Nuclides selection method for nuclear reactor shielding based on non-dominated sorting

The primary purpose of nuclear reactor shielding is to protect the internal structure and staff from radiation damage. In this paper, the non-dominated sorting method is proposed for shielding material selection, which is based on the single-group cross-sections condensed using the neutron energy spectrum. This sorting is applied to the Pressurized Water Reactor (PWR) and Sodium-cooled Fast Reactor (SFR) and contrasted with the Reactor Monte Carlo code (RMC). The results show that the coincidence rates between the non-dominated sorting and the RMC for neutron, photon, and neutron-photon shielding in PWR are 95%, 98.95%, and 94.87%, while in SFR they are 72.5%, 95.79%, and 82.5%. The calculation time for the non-dominated sorting is less than 3% of the RMC. It provided an efficient method for the selection of shielding nuclides for different kinds of reactors.

Study of the Impact of Tube Configurations on the Local Heat Transfer Coefficient in Mimicked Fischer-Tropsch Bubble Column Reactor

An experimental investigation was conducted to examine, for the first time, the influences of using different designs of tube arrangements on the local heat transfer coefficient (LHTC) in a bubble column (with a diameter of 0.13 m) equipped densely with a bundle of tubes. The effect of using two different designs of tube arrangements has been examined for a broad range of gas flow rates using a sophisticated heat transfer technique. The obtained results indicate that the LHTC increases significantly with increasing the gas velocity, regardless of the design and installation of the tubes in the column. Additionally, the shape of the LHTC’s profiles alters considerably by the presence of a bundle of tubes and their arrangements. Moreover, the results indicate that the square tube pitch arrangement provides uniform heat transfer profiles, which enhance the performance of the bubble column reactor by 30%. Furthermore, the heat transfer profiles were found to be varied with the axial height of the column. The new experimental results obtained in this investigation will provide experimental reference data for creating and validating a mathematical model for predicting LHTCs. In addition, this will facilitate this kind of reactor’s design, scale-up, and operation.

High-Efficient Hydrogen Generation Study by a Reverse Tailing Pulsed-Plasma Water Dissociation Applying Wet Electrode Method

A pulsed power water dissociation method applying a couple of a porous-ceramic electrode, wetted with water, and an opposite dry electrode in the atmospheric air was studied. The basic concept for this study is composed of “pulsed power activation of high water particle density liquid state at the porous electrode creepage” and “subsequent non-thermal equilibrium plasma reactions of these particles diffusing into the low water particle density gas state.” The deionized water (DIW) dissociation experiments were performed by applying the Reverse Tailing Pulse (RTP) method, where the forward pulse voltage of 10 kV level with the rising up ratio (dV/dt) of 1011 V s−1 level is applied. To examine the electric polarity contribution, four kinds of reactors were studied. H2 was detected in one reactor which is composed of an anode electrode made by porous-ceramic, wetted with DIW, and a cathode electrode made from a dry fine-ceramic. The H2 generation efficiency, close to the theoretical prediction, was obtained when “Tanzanite” colored plasma was detected. These features may be due to the “RTP” reformation of the high water particle density liquid state in the wetted porous-electrode creepage and their continuous diffusion into the gas plasma space with the help of “Fick’s law of diffusion” and “pulsed ion wind.”

Air-lift Reactor's Characterization via Computational Fluid Dynamic (CFD): Review

Airlift reactors are seen as the most promising reactor for many valuable productions such as algae culturing. However, this kind of reactor still needs more information and data to understand its phenomena due to limited studies. Also, to reduce the time and offers obtained with sufficient reactor design, capable of achieving high productivities, Computational Fluid Dynamics (CFD) could play an important role in optimizing the reactor design by analyzing the interaction of hydro-dynamics. This review presents the literature review on the recent CFD work for such a reactor that addressed the fluid dynamics parameters, such as bubble dynamics. Earlier researches find more reports utilizing uniform bubble diameter in CFD simulations. However, the latest research in the CFD modeling of multi-phase flow reactors showed that the description of the bubble has significant effects on the performance of the simulation. As a result, systematic research into the impact of bubble diameter on the simulation results of the CFD was performed. Finally, we present and discuss the CFD modeling approaches, a Governing equation such as Eulerian-Eulerian (E-E), and closure such as the drag force.

Multiphysics Optimization for First Wall Design Enhancement in Water-Cooled Breeding Blankets

The commercial feasibility of the first fusion power plant generation adopting D-T plasma is strongly dependent upon the self-sustainability in terms of tritium fuelling. Within such a kind of reactor, the component selected to house the tritium breeding reactions is the breeding blanket, which is further assigned to heat power removal and radiation shielding functions. As a consequence of both its role and position, the breeding blanket is heavily exposed to both surface and volumetric heat loads and, hence, its design requires a typical multiphysics approach, from the neutronics to the thermo-mechanics. During last years, a great deal of effort has been put in the optimization of the breeding blanket design, with the aim of maximizing the tritium breeding and heat removal performances without undermining its structural integrity. In this paper, a derivative-free optimization method named “Complex method” is applied for the design optimization of the European DEMO Water-Cooled Lithium Lead breeding blanket concept. To this purpose, a potential performances-based objective function, focusing on the maximization of the tritium breeding, is defined and a multiphysics numerical model of the blanket is developed in order to solve the coupled thermo-mechanical problem, while the optimization algorithm leads the design towards a minimum optimum point compliant with the prescribed requirements. Once the optimized design is obtained, its nuclear and thermo-structural performances are assessed by means of specific neutron transport and multiphysics simulations, respectively. Finally, the structural integrity is verified by means of the application of the RCC-MRx design criteria. • A tool for First Wall optimization in water-cooled breeding blankets is developed. • The optimization is performed using the gradient-free method named “Complex method”. • An objective function aiming at tritium breeding maximization is defined. • A FE model is used to check the compliance with the thermo-structural requirements. • The optimized design is finally assessed by proper, more detailed numerical analyses.

CYCLES OF SOLAR ACTIVITY AS A BASIS FOR FORECASTING THE QUALITY OF DNIEPER WATER

One of the main features of the quality of the Dnieper water is the content of natural organic substances which determine the water oxidizability and color indexes. A special problem is that organic substances are poorly removed by water treatment plants. A significant problem in the operation of water treatment plants is the unpredictability of annual changes in the quality of Dnieper water, which complicates logistics management, for example, the supply of reagents. Many years of experience related to the Dnieper water supply station in Kyiv (DnWS) have led to the hypothesis that these changes are in some way related to the cycles of solar activity.&#x0D; The purpose of this work is to test this hypothesis to substantiate the possibility of predicting the quality of Dnieper water depending on the action of such a global factor as solar activity. The work was performed by statistical methods using 60-year results of Dnieper water analyzes provided by the DnWS laboratory, as well as Wolf numbers (Sunspot Numbers) provided for free use by the Royal Observatory of Belgium. The influence of solar activity on the quality indicators of Dnieper water, especially in its peak and post-peak periods, has been statistically confirmed. The interaction of biological and physicochemical parameters as factors influencing water quality is shown.&#x0D; Conclusions. As a result of the construction of six reservoirs in 1931-1976, the Dnieper from the river actually turned into a network of water bodies. Now these reservoirs are a kind of reactors in which water is treated by electromagnetic solar radiation, which leads to the cyclic transformation of phytoplankton and natural organic matter. Taking into account the cycles of solar activity, the logistical planning of the operation of water treatment facilities receives an independent "base", changes in which can be predicted with some reliability for years to come.

Computational study of particle distribution development in a cold-flow laboratory scale downer reactor

The use of downer reactors (gas-solid co-current downward flow) in the Fluid Catalytic cracking (FCC) process for the upgrading of heavy crude oil into more valuable products has gradually become more common in the last decades. This kind of reactor is characterized by having homogeneous axial and radial flow structures, no back mixing, and shorter residence times as compared with the riser reactor type. Although downer reactors were introduced a long time ago, available information in literature about the multiphase hydrodynamic behavior at FCC industrial scale is scarce. Therefore, it is necessary to conduct experimental and computational studies to enhance the understanding of the hydrodynamics of two-phase co-current downward flow. The Computational Fluids Dynamics (CFD) software, Ansys Fluent, is used to study two-dimensional gas (air) and solid (catalyst particle) flow in a downer section of a cold-flow circulation fluidized bed (CFB) system at a laboratory scale. The implemented computational model is validated by comparing numerical results for solid velocity and volume fraction with measurements carried out on a CFB system using a fiber-optic probe laser velocimeter. According to numerical results obtained for different gas velocity and solid flux, flow development cannot only be estimated by considering solid axial velocity changes along the reactor; it is also necessary to take into account solid volume fraction axial variations as radial profiles can change even when velocity profiles are developed.

Reactors and active biomass potential as inoculum for nitrogen removal

The potential of three different kind of reactors and active biomass to be used as inoculum for nitrogen removal was verified. Sludge samples were collected from a Membrane Bioreactor (MBR), a previous tank of a Moving Bed Biofilm Reactor (MBBR) and a Trickling Filter (TF). Samples were compared according to bacterial activity in batch tests and their microbiology (16 s rRNA sequences). The microorganisms examined were: AOB, NOB, anammox bacteria and OHO. Results showed that the richest sample was from MBR (Chao value equals 581). However, the bacterial activity was greater in MBBR sample (qAOO,NH4 equals 0.002 mgN·mgVSS−1·h−1; qNOO,NO2_NO3 equals 0.001 mgN·mgVSS−1·h−1 and qNOX_N2,SB equals 10.0 mgN·mgVSS−1·h−1). Therefore, MBBR WWTP was shown to have the best inoculum and operating conditions for nitrogen conversion and removal. Besides, if aeration is provided as low as necessary for AOB to start the activity in denitrification tank, simultaneous partial nitrification, and denitrification (SPND) can occur.

Numerical simulation of two-phase flow and droplet breakage of glycerin-water mixture and kerosene in the cyclone reactor

• The static pressure distribution conformed with the rules of the eddy field. • The vortex motion near the side wall was intense. • The droplet deformed, stretched, and broken. • The small surface tension and large Weber number promoted droplet breakage. A liquid-liquid cyclone reactor (LLCR) was designed to achieve mixing-reaction-separation integration during isobutane alkylation catalyzed by ionic liquids. However, studies of the droplets deformation and breakage in the kind of reactors are lacking. In this work, the research studied the velocity distribution, pressure field, and turbulent field to investigate the flow pattern and the main energy loss location in the LLCR through the computational fluid dynamics (CFD) method. The simulation results were verified by experiemnts to prove the correctness of the model. Then the deformation and breakage process of droplets, and the influencing factors of droplets breakage were studied by remodeling which was based on the tangential velocity distribution result of the three dimensional model. The three dimensional simulation results clearly showed that the pressure of the LLCR was mainly concentrated in the cone section and fluid turbulent motion was the most intense near the lateral wall. The reconstruct the results of the two dimensional model clearly showed that the deformation and breakage location of droplets were mainly occurred in the velocity boundary layer, while it was difficult to break in the mainstream region. In addition, low surface tension and high Weber number had a positive effect on droplet breakage.

Open Flow Reactors Prepared by Laser Sintering

AbstractThe open flow reactor is a kind of reactor with at least one side open to the atmosphere. Open channels have the advantages of simple surface modification, direct cleaning, and relatively simple manufacturing methods. In this article, laser sintering is used to prepare a new type of open flow micro‐reactor. Laser sintering can adjust the surface wettability of phenolic resin to produce hydrophilic and hydrophobic regions, which lead to the formation of open flow reactors. Laminar flow and mixing processes, which usually happen in regular flow reactors, are also observed in the open‐channel reactor. The phenolic resin film can be doped with iron to catalyze the degradation of organic pollutants when they flow along the channel. The catalytic efficiency can still be maintained at about 80% after 8 h degradation. This work will inspire the development of open flow reactors and further expand the practical application of laser‐sintered materials.

Simulation based investigation of 2D soft-elastic reactors for better mixing performance

Inspired by the animal upper digestive tract, a unique soft-elastic reactor (SER) has recently been researched whose mixing phenomena should be further investigated. Numerical simulation is an excellent method with which to explore the phenomena in SERs for a large number of conditions. It may also offer insights into the ways of effective mixing in this kind of reactor. The mixing processes in 2D SERs driven by bio-inspired wavelike boundary motions are systematically compared in this work. The influences of several key factors (i.e. the aspect ratios of rectangular SERs, the wavenumbers of moving walls, and the location and size of baffles) on the mixing performance are investigated. It has been found that mixing efficiency is better at an aspect ratio close to 1.0. The influence of wavenumber on mixing is not monotonic. Increasing the wavenumber speeds up mixing in parallel boundary type motion, while it slows it down in symmetrical-contraction boundary type motion. Mounting baffles on the left and right sides of the vessel wall (i.e. on the moving boundaries) promotes mixing. Lower porosity (≤ 0.4) of baffles benefits mixing. It has become clear that an efficient SER needs to be designed by considering not only its shape but also the wall moving mode. The work reported in this article has provided useful information on how it might be possible to improve SERs for industrial applications in future.

Process Intensification through Directly Coupled Autothermal Operation of Chemical Reactors

Summary Autothermal operation of a chemical reactor involves coupling exothermic and endothermic chemical reactions for the purpose of thermal management without resorting to external energy sinks or sources. Often this is accomplished through regenerative or recuperative heat exchange between spatially or temporally separated exothermic and endothermic reactions. However, it is also possible to directly couple these reactions simultaneously within the same reactor volume, eliminating the heat-transfer bottleneck that characterizes much of chemical manufacture. It is not widely recognized that directly coupled autothermal operation allows dramatic process intensification. This perspective defines autothermal operation and contrasts it with conventional heat transfer for thermal management of chemical processes. The intensification and cost savings that can be achieved are quantified, and the implications to modular chemical process intensification are presented. Guidelines are proposed for designing directly coupled autothermal processes. Diverse examples are presented. Several challenges to expanding the field are critically discussed.

A continuous hydrogen absorption/desorption model for metal hydride reactor coupled with PCM as heat management and its application in the fuel cell power system

In this work, the model of metal hydride reactor coupled with phase change material (PCM) as heat management is modified to describe the heat and mass transfer behaviors of the continuous hydrogen absorption/desorption processes better. Through the experimental validation, the modified model is proven to be more accurate than the traditional model. Based on the proposed model, the performance of the metal hydride reactor is further optimized by the parametric analysis, property and configuration modification. The results show that the metal hydride reactor achieves a hydrogen storage efficiency of 47% at the phase change temperature of 42 °C, which is higher than at 35 and 49 °C. By adding expanded graphite into PCM, the hydrogen storage efficiency can increase up to about 72%, which is higher than the previously reported efficiency of 69%. This is because of the enhanced heat transfer between metal hydride and PCM. Accordingly, the hydrogen absorption time is significantly shortened to no more than 5 min. In addition, it is suggested to operate the reactor in the hydrogen desorption pressure of 2–8 bar and the temperature of 32–58 °C for the improved performance, when this kind of reactor is applied in the fuel cell power system as hydrogen source.

Measuring the air fraction and the gas temperature in non-thermal argon plasma jets through the study of the air influence on the collisional broadening of some argon atomic emission lines

Cold atmospheric argon plasma jets have shown to be very promising in medicine and they are being currently used for therapeutical uses such as the healing of wounds or the treatment of tumors. Because they run in the open atmosphere, they generate copious amounts of reactive oxygen and nitrogen species, which play an outstanding role in their biological action. But, in this kind of reactor, unknown amounts of air enter the plasma region depending on the experimental conditions, changing the chemistry in them, and eventually their effects. In this work, we propose a new spectroscopic method to measure the amount of air in argon non-thermal (including cold atmospheric) plasma jets through the collisional broadening of Ar I 840.86 and Ar I 842.46 nm emission lines. The method allows the simultaneous determination of the gas temperature. For validation purposes, it was applied to a microwave-induced plasma jet working at different operational conditions. Results were consistent with those obtained from the rotational temperature derived from simulations of N2 (2nd positive system) rovibrational band.

Modular high temperature gas reactor core modeling with RELAP5-3D/PHISICS – Optimization schemes for load following

The objective of this study is to develop a 3D neutron kinetic (NK) and thermal hydraulic (TH) coupled model using the INL developed code RELAP5-3D©/PHISICS to study the load following operation of a Modular High-Temperature Gas-Cooled Reactor (MHTGR). The selected design is the 350 MW prismatic, graphite moderated, helium cooled thermal reactor based on the MHTGR-350 transient benchmark led by the High-Temperature Gas-Cooled Reactor (HTGR) Methods Core Simulation Group at Idaho National Laboratory (INL) in the framework of the Organization for Economic Cooperation and Development Nuclear Energy Agency (OECD/NEA).This kind of reactor usually reacts very slowly to the perturbation of the core parameters due to the large amount of graphite in the core. This kind of behavior promotes the reactor stability but on the other hand limits the reactor load-following operability. Recently advances in gas reactor designs have made load-following a feasible and achievable goal. Modern nuclear reactors (such as the MHTGR-350) are designed to withstand the structural stresses associated with load-following. Operating the reactor in load-following mode will inevitably reduce the load factor. Although a higher load factor means more revenue and the best usage of the fuel, following the variable energy demand will increase the maximum achievable fraction of generated nuclear power, being no more limited to the base load power generation. In general, if low impact on material aging and the safe operability are demonstrated, the plant economics will be minimally affected. In order to ensure that the system can be safely operated in a load-following mode, an extensively study has been carried out. Some tests with linear change in coolant mass flow rate demonstrated that the reactor behavior is suitable for operation in load following mode. This assumption has been confirmed by a 4 days load following transient test in which the reactor supplied the requested power with a negligible error.

Non-ideal flow model for a tubular reactor and a stirred tank reactor in-series, using stimulus-response techniques

This work presents an experimental study on a laboratory scale about the hydrodynamic behavior of fluid flow in a tubular reactor and a stirred tank reactor in-series and varying their arrangement. The experiments were carried out using stimulus-response techniques with a tracer solution of sodium chloride in unit pulse form. The experimental results allowed obtaining the Residence Time Distribution curves Rθ vs θ for different reactor arrangements. The results obtained are similar to those reported by Levenspiel for a battery in-series with a plug flow reactor and a perfectly stirred reactor. The difference found with the studied system is that these show dead water in both equipment. The arrangement of the reactors does not modify the graph of Residence Times Distribution obtained, similar to the ideal situation presented in the literature consulted. As a result of the experimental study and the adjustment of the data, a non-ideal flow model was obtained for different kinds of reactors with dead water, connected in-series and with different arrangements. The simulation of the system for different degrees of back mixing in the system reflects a behavior similar to that of series of reactors of this type, but with ideal behavior.