Tube Reactor Research Articles

Spontaneous Phase Segregation Enabling Clogging Aversion in Continuous Flow Microfluidic Synthesis of Nanocrystals Supported on Reduced Graphene Oxide

Eliminating clogging in capillary tube reactors is critical but challenging for enabling continuous-flow microfluidic synthesis of nanoparticles. Creating immiscible segments in a microfluidic flow is a promising approach to maintaining a continuous flow in the microfluidic channel because the segments with low surface energy do not adsorb onto the internal wall of the microchannel. Herein we report the spontaneous self-agglomeration of reduced graphene oxide (rGO) nanosheets in polyol flow, which arises because the reduction of graphene oxide (GO) nanosheets by hot polyol changes the nanosheets from hydrophilic to hydrophobic. The agglomerated rGO nanosheets form immiscible solid segments in the polyol flow, realizing the liquid-solid segmented flow to enable clogging aversion in continuous-flow microfluidic synthesis. Simultaneous reduction of precursor species in hot polyol deposits nanocrystals uniformly dispersed on the rGO nanosheets even without surfactant. Cuprous oxide (Cu2O) nanocubes of varying edge lengths and ultrafine metal nanoparticles of platinum (Pt) and palladium (Pd) dispersed on rGO nanosheets have been continuously synthesized using the liquid-solid segmented flow microfluidic method, shedding light on the promise of microfluidic reactors in synthesizing functional nanomaterials.

Corrosion behavior of zirconium alloy fuel assembly cladding tubes in the pressurized water reactor’s primary circuit

Corrosion behavior of zirconium alloy fuel assembly cladding tubes in the pressurized water reactor’s primary circuit

Intensifying biofuel production using a novel bionic flow-induced peristaltic reactor: biodiesel production as a case study

Intensification of biofuel production processes could play a critical role in boosting the economic and environmental features of the whole process. A novel bionic flow-induced peristaltic reactor with a high conversion rate is constructed to realize efficient biofuel production from high-concentration high-viscosity fluids. It is experimentally verified through biodiesel production from soybean oil. Experimental results show that the conversion efficiency is up to 89.9% at 10 s in the peristaltic reactor, which is 38.4% higher than that in the rigid tube reactor. Furthermore, a three-dimensional peristaltic model is conducted to understand the mechanism of heat and mass transfer enhancement. The simulation results show that an increase in peristaltic amplitude strengthens the mixing of the bionic peristaltic reactor by 92.5-100.8%. The temperature distribution in the bionic peristaltic reactor is more uniform than in the traditional rigid tube reactor. The results demonstrate that the conversion rate of soybean oil in the bionic flow-induced peristaltic reactor is 528.82% min-1, which is 17-60 times higher than other intensified reactors operating in either continuous or batch modes.

Ecological synthesis of nickel–zinc–aluminium layered double hydroxides (Ni–Zn–Al LDH) in flow infrared radiated agitated tubular reactor (flow-IR-ATR)

The yield of obtaining layered double hydroxides (LDHs) remains a significant challenge that limits their practical use on a large scale. The use of flow processes is an innovative approach to solving the problem. This paper describes a method for obtaining LDH nanoparticles using an agitated tube reactor heated by infrared radiation (flow-IR-ATR). As a dedicated reactor for production of LDH nanoparticles, it is able to synthesise products at a flow rate of 1.8 dm3/h and a yield of 40 g/h. In the process, LDH NPs based on zinc–aluminium hydroxides (Zn–Al LDH) and LDH NPs modified with nickel hydroxide (Ni–Zn–Al LDH), with molar ratio of Ni to Zn 0.5, were obtained. Instrumental analyses (XRD, FTIR, SEM, DLS, BET, XPS) were used to characterise the LDH nanoparticles obtained, which showed crystallite sizes from 9 to 35 nm. The nickel-containing LDHs exhibited high photocatalytic activity. After 60 min, in the presence of UV radiation (365 nm), the photodegradation efficiency of quinoline yellow (dye concentration of 100 mg/dm3) was more than 99.9%.Graphical

Features of Deactivation and Regeneration of the Zeolite-Containing Cobalt Catalyst in a Fischer – Tropsch Synthesis Reactor

Endurance tests of the zeolite-containing cobalt catalyst for the Fischer – Tropsch synthesis were carried out in reactor tubes of the size comparable with those used in industrial reactors. During the tests (3000 h), the catalyst activity decreased by 13 %. Deactivation of the zeolite-containing cobalt catalyst was shown to occur due to agglomeration of cobalt clusters and formation of amorphous carbon on their surface. A method of decreasing the catalyst deactivation rate and two methods of the catalyst regeneration were proposed. The method of redox regeneration of zeolite-containing cobalt catalysts allows restoring 98 % of their initial activity.

The application of a novel 5-in-1 multiplex reverse transcriptase–polymerase chain reaction assay for rapid detection of SARS-CoV-2 and differentiation between variants of concern

To rapid detect for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and immediately distinguish whether positive samples represent variants of concern (VOCs), we established a novel 5-in-1 VOC assay. This assay could distinguish among five VOCs: Alpha, Beta, Gamma, Delta, and Omicron, in a single reaction tube. The five variants exhibit different single nucleotide polymorphisms (SNPs) in their viral genome, which can be exploited to distinguish them. We selected target SNPs in the spike gene, including N501Y, P681R, K417N, and deletion H69/V70 for the assay. The limit of detection of each gene locus was 80 copies per PCR reaction. We observed a high consistency among the results when comparing the performance of our 5-in-1 VOC assay, whole gene sequencing, and the Roche VirSNiP SARS-CoV-2 test in retrospectively analyzing 150 clinical SARS-CoV-2 variant positive samples. The 5-in-1 VOC assay offers an alternative and rapid high-throughput test for most diagnostic laboratories in a flexible sample-to-result platform. The assay can also be applied in a commercial platform with completion of the SARS-CoV-2 confirmation test and identification of its variant within 2.5 hours.

Naked-Eye Detection of Food-Borne Pathogens Using Multiplex Hyperbranched Rolling Circle Amplification and Magnetic Particles

Food safety is a significant public health issue in both developed and developing countries. Previous detection methods struggle to meet the current demands. We have proposed a new way to detect pathogens, allowing detection to be visualized by the naked eye. Using our newly developed assay, when target genes are present in the reaction, corresponding padlock probes form closed-loop molecules. Each reaction tube contains a pair of universal primers for identifying target genes. The ring padlock probes and corresponding universal primers start hyperbranched rolling circle amplification (HRCA) under the action of the polymerase, so as to gain branched chain amplification products, which are irreversibly entangled with magnetic particles to form aggregated magnetic particle clusters, and the detection results are visible to naked eyes. On the contrary, by using linear probes, the clustering of magnetic particles will not be produced. This method was applied to the detection of five food-borne pathogens enterohemorrhagic Escherichia coli (EHEC), enterotoxigenic Escherichia coli (ETEC), enteropathogenic Escherichia coli (EPEC), enteroinvasive Escherichia coli (EIEC) and Escherichia coli (E. coli), with detection limits of 1 × 103, 1 × 104, 1 × 103, 1 × 104 and 1 × 102 CFU/mL, respectively. This method can realize multiplex automatic detection of nucleic acid and shows great development potential in the field of molecular diagnosis.

Physical phenomena of a cold plasma jet model at atmospheric pressure

In this work, a two dimensional (2D) axisymmetric fluid model for an atmospheric pressure plasma jet (APP jet) driven by a 8 kV voltage pulse with a repetition frequency of 50 kHz has been investigated. The aim is to identify the physical phenomena taking place in a cold plasma jet at atmospheric pressure assuming an argon pathway in the air. This model is a platform for future works where the simulated reactor will be used for different plasma jet applications. It is built through the coupling between plasma discharge and flow physics using COMSOL@ Multi-physics software. The simulation results showed that the high value of the electric field in the head of the plasma jet channel attracts free electrons and ensures its propagation to around 1cm of length with an electron density of 1020 m−3. We have also shown that electrons in the neutral zone of the plasma (channel) have a lower temperature compared to electrons in electrostatic sheaths (channel boundaries), although, their temperature remains remarkably higher than neutrals and ions ones. The total electric current calculated by the proposed model takes a maximum value of 7.71 mA. This value increases with increasing tube reactor diameter which changes the reactor equivalent capacity.

Holdup of sub-granules towards enhanced production of anammox sludge in a dual circulation sludge bed reactor

The performance of anammox process largely depends on the anammox sludge as the functional core. Enhancing the production and retention of anammox sludge in the reaction system was a hot while pressing issue to be addressed for the application of the anammox process. In this study, a novel reactor named Ducan (Dual Circulation Anammox) was developed to achieve promoted production of anammox sludge, and the mechanism was revealed meanwhile. It was found that the Ducan reactor could improve the sludge production rate by 96.2 % compared with the control group. The enhanced formation of new-born anammox granular sludge (AnGS) by holding up the wash-out anammox sludge was believed to be the main factor contributing to this result. Furthermore, the typical structure of the new-born AnGS was characterized and the sub-granule (SG) on a 100 μm scale was revealed as its direct structural unit. Vulnerable disassembly of aged AnGS was the main source of SG due to the weak binding force of AnGS caused by the formation of large cavities inside. By setting a unique structure of dual-systolic tubes in the Ducan reactor, the SG was endowed with reduced surface roughness and increased EPS protein with hydrophobic amino acids and a looser structure. These properties made it easier for SG to contact each other and assembled into new-born AnGS with big size, which could then settle back to the reactor and result in enhanced production of anammox sludge. The results in this study were expected to offer a viable reactor towards enhanced production of AnGS, and shed light on addressing the issue of sludge shortage during the extensive application of anammox technology.

Design and optimization of a crossflow tube reactor system for hydrogen production by combining ethanol steam reforming and water gas shift reaction

Crossflow tube reactors with crossflow configuration are considered a special design for hydrogen production via ethanol steam reforming with less catalyst than conventional packed bed reactors. However, the results showed that crossflow tube reactors would produce an elevated concentration of carbon monoxide, which has a detrimental effect on further applications of the product gas from steam reforming, such as hydrogen purification. This drawback can be diminished by integrating a water gas shift reaction unit into the steam reformer. This study's combined system is numerically investigated for hydrogen production and enrichment. The results show that low reaction temperatures are favorable for hydrogen production. The steam/ethanol (S/E) ratio of 3 is optimal for hydrogen production and CO reduction in the system combined with ethanol steam reforming and water gas shift reaction. Both variations in the catalytic tube diameter and the catalyst thickness positively affect hydrogen production. However, the effect of the tube diameter is higher than that of the catalyst thickness. This study also uses a parametric sweep associated with the evolutionary computation of bound optimization by quadratic approximation (BOBYQA) method to optimize the system’s tube arrangement. The optimized system intensifies H2 yield by 1.05 times and improves CO reduction by 37.71% compared to ethanol steam reforming alone.

Numerical investigation of a thermal energy storage system based on the serpentine tube reactor

Thermochemical heat storage (TCHS) technology is widely concerned for its high energy storage density (ESD) and long-term storage of energy in the form of chemical energy for long-term thermal storage applications. TCHS with hydrated salt as the thermochemical material (TCM) has low regeneration temperature, clean reaction products, and appropriate heat release temperature, which is suitable for the application of medium and low temperature applications. A 3D numerical model is developed to simulate and understand the hydration (heat discharging) process of the serpentine tube reactor filled with hydrate of K2CO3. The coupled multiphysics includes fluid flow, heat and mass transfer, and chemical reaction process. Variations of hydration characteristics, such as temperature and conversion, are discussed in detail. The heat discharging processes at different vapor pressure (1200 Pa–1600 Pa) and different inlet flow rates (0.5–5 m/s) of heat transfer fluid (HTF) are investigated. It is found that higher vapor pressure can significantly increase output temperature, and a higher HTF inlet flow rate can improve overall heat exchange performance. By increasing the vapor pressure from 1200 Pa to 1600 Pa, the maximum outlet temperature lift could be significantly increased by 7.9 %. However, pipe shape has little effect on enhancing the performance of the reactor.

Rate constant determination in the reaction of gold ion with carbonyl using single-atom chemistry in gas phase

The reactions of single gold ion Au+ with CO and H2O molecules in gas phase were studied by experiment and calculation. A reaction tube was connected to the end of the jet to destroy the supersonic state of the molecular beam and enhance the collisions between the laser-sputtered metal ions with gas molecules, so as to ensure the equilibrium reaction conditions. The ionic products were analyzed by a time-of-flight mass spectrometer. The collision temperature in reaction tube was calibrated to 409 K by the reaction of Au+ ion and H2O molecules. The contents of ionic products Au(CO)+ and Au(CO)2+ in the reaction of Au+ with CO molecules were monitored under different concentrations of CO in precursor gas. The combination reaction rate constants of single Au + ion sequentially with two CO molecules were determined to be k1 = 1.1 (2) × 10−12 cm3s−1 and k2 = 4.5 (5) × 10−10 cm3s−1. The geometric structures and binding energies of the ionic products, as well as the pathway and rate constants of the reactions were predicted by a high-level ab initial calculation. The binding mode of Au+ and CO and the formation of molecular orbital were discussed.

A Simple Cost-Effective Method for Whole-Genome Sequencing, Haplotyping, and Assembly.

In this chapter, we describe single-tube long fragment read (stLFR), a simple preparation method for whole-genome sequencing and physical haplotyping based on the DNA co-barcoding strategy. Similar to LFR, stLFR applies the concept of adding the same barcode to subfragments derived from the same long DNA molecule. However, instead of a 384-well plate, stLFR uses the surface of micron-sized magnetic beads to create millions of virtual compartments in a single reaction tube. This is enabled by a split and pool barcoded bead preparation process capable of generating ~500,000 copies of the same unique barcode, from a library of ~3.6 billion unique barcodes, on each bead. The instruments and devices used in the stLFR process are easily accessible in nearly all standard molecular biology laboratories, and the cost of reagents can be as low as 30 dollars per sample. stLFR libraries can be sequenced by standard second-generation sequencing instruments (e.g., MGI or Illumina devices), and the barcode sharing information enables detection and phasing of all variations, including large structural variations. In addition, stLFR data can be used to scaffold contigs and de novo assemble genomes.

An integrated instrument of a tandem quadrupole mass spectrometer for cluster reaction and soft-landing deposition.

We have developed an integrated instrument system of a multiple-ion laminar flow tube (MIFT) reactor combined with a tandem quadrupole mass spectrometer (TQMS) and soft-landing deposition (SD) apparatus. A customized water-cooling magnetron sputtering (MagS) source is designed, by which we are able to attain a highly efficient preparation of metal clusters of 1-30 atoms with tunable size distributions. Following the MagS source, a laminar flow tube reactor is designed, allowing for sufficient gas-collision reactions of the as-prepared metal clusters, which is advantageous for probing magic clusters and minimizing wall effects when probing the reaction dynamics of such clusters. The customized TQMS analyzer involves a conical octupole, two linear octupoles, a quadruple ion deflector, and a 19mm quadruple mass analyzer, allowing to decrease the pressure stepwise (from ∼5 to ∼10-9 Torr), thus ensuring high sensitivity and high resolution of the mass spectrometry analysis. In addition, we have designed a dual SDapparatus for the mass-selected deposition of clusters and their reaction products. For the whole system, abbreviated as MagS-MIFT-TQMS-SD, we have performed a detailed ions-fly simulation and quantitatively estimated the ions transfer efficiency under vacuum conditions determined by real experiments. Taking these advantages, well-resolved Pbn +, Agn +, and Nbn + clusters have been produced, allowing for meticulous studies of cluster reactions under sufficient gas-phase collisions free of electric field trapping. Also, we have tested the efficiency of the dual SD.

ANALISIS TEMPERATUR PADA PROSES TERBENTUKNYA BAHAN BAKAR MINYAK (BBM) DENGAN METODE PIROLISIS PADA PROTOTYPE ALAT PENGOLAH LIMBAH PLASTIK MENJADI BBM

The physical properties of plastic waste that is not easily biodegradable is a serious problem in pollution on land and at sea. Therefore, technology to be able to solve these problems needs to be developed. This study aims to understand at what temperature plastic waste can produce fuel oil. The type of waste used in this research is polyethylene terephthalate (PET), which is a type of plastic that uses drink bottles. The design of the device to convert plastic into fuel oil in this study consisted of 3 components, namely a valve which functions to regulate the flow of steam from the reactor tube to the condensate tube, the temperature gauge functions to measure the temperature contained in the reactor tube, and the heat blanket functions as a coating, this can reduce excessive heat in the reactor tube. The results revealed that at a temperature of 100ºC to 150ºC with a variation of time (26.3, 27.3, and 28) minutes did not produce oil. At a temperature of 200ºC to 250ºC with time variations (33, 34, and 35) minutes, the condensate tube begins to produce fuel above the water surface.

Phase State and Relative Humidity Regulate the Heterogeneous Oxidation Kinetics and Pathways of Organic-Inorganic Mixed Aerosols.

Inorganic species always coexist with organic materials in atmospheric particles and may influence the heterogeneous oxidation of organic aerosols. However, very limited studies have explored the role of the inorganics in the chemical evolution of organic species in mixed aerosols. This study examines the heterogeneous oxidation of glutaric acid-ammonium sulfate and 1,2,6-hexanetriol-ammonium sulfate aerosols by hydroxyl radicals (OH) under varied organic mass fractions (forg) and relative humidity in a flow tube reactor. Coupling the oxidation kinetics and product measurements with kinetic model simulations, we found that under both low relative humidity (RH, 30-35%) and high RH conditions (85%), the decreased forg from 0.7 to 0.2 accelerates the oxidation of the organic materials by a factor of up to 11. We suggest that the faster oxidation kinetics under low-RH conditions is due to full or partial phase separation, with the organics greatly enriched at the particle outer region, while enhanced "salting-out" of the organics and OH adsorption caused by higher inorganics could explain the observations under high-RH conditions. Analysis of the oxidation products reveals that the dilution of organics by the inorganic salts and corresponding water uptake under high-RH conditions will favor alkoxy radical fragmentation by a factor of 3-4 and inhibit its secondary chain propagation chemistry. Our results suggest that atmospheric organic aerosol oxidation lifetime and composition are strongly impacted by the coexistent inorganic salts.

Peroxy Radical Autoxidation and Sequential Oxidation in Organic Nitrate Formation during Limonene Nighttime Oxidation.

Limonene is an abundant monoterpene released into the atmosphere via biogenic emissions and biomass burning. However, the atmospheric oxidation and secondary organic aerosol (SOA) formation mechanisms of limonene, especially during nighttime, remain largely understudied. In this work, limonene was oxidized synergistically by ozone (O3) and nitrate radicals (NO3) in a flow tube reactor and a continuous flow stirred tank reactor. Upon oxidation, many highly oxidized organic nitrates and nitrooxy peroxy radicals (RO2) were observed in the gas phase within 1 min. Combining quantum chemical calculations with kinetic simulations, we found that the primary nitrooxy RO2 (C10H16NO5) through NO3 addition at the more substituted endocyclic double bond and at the exocyclic double bond (previously considered as minor pathways) can undergo autoxidation with rate constants of around 0.02 and 20 s-1 at 298 K, respectively. These pathways could explain a major portion of the observed highly oxidized organic nitrates. In the SOA, highly oxidized mono- and dinitrates (e.g., C10H17NO7-8 and C10H16,18N2O8-10) make up a significant contribution, highlighting nitrooxy RO2 autoxidation and sequential NO3 oxidation of limonene. The same organic nitrates are also observed in ambient aerosol during biomass burning and nighttime in the southeastern United States. Therefore, the present work provides new insights into the nighttime oxidation of limonene and SOA formation in the atmosphere.

Temperature dependent Raman spectra of pure, gaseous formaldehyde for combustion diagnostics

The combustion of renewable fuels such as methanol or ethanol produces comparatively large concentrations of formaldehyde (CH2O) as a combustion intermediate. This intermediate needs to be quantitatively measured using non-intrusive laser diagnostics to provide a better understanding of the chemical processes in the reaction zone. Spontaneous Raman scattering is used in reactive flow diagnostics to measure spatially resolved species concentrations. For diagnostics of CH2O using Raman scattering, the temperature-dependent Raman spectra of gaseous CH2O are required, but not yet available. One reason for this is that gaseous CH2O polymerizes very rapidly, especially at higher temperatures, and can only be made available in pure form for spectroscopic investigations by specific preparation. For this purpose, a continuous flow reactor was developed in which trioxane is pyrolyzed to monomeric CH2O by means of thermal decomposition in a tube reactor. Using a CW-Raman spectrometer, the products of a thermal decomposition at isothermal conditions are analyzed downstream of the tube reactor and CH2O is detected as the only product of the pyrolysis process. Raman spectra of gaseous CH2O are characterized for the first time using the continuous flow system. The Raman scattering in the CH-bend and CH-stretch regions show characteristic bands, which are, for instance, different in the spectral position to the ones from ethanol, allowing for a spectral discrimination. Raman cross sections reveal that the harmonic-oscillator assumption substantially deviates for the tetratomic CH2O, which underlines the relevance of an experimental characterization at elevated temperatures. Finally, the flow systems developed for the generation of monomeric gaseous CH2O can potentially be employed to improve diagnostics, such as laser induced fluorescence for a quantitative measurement of CH2O.

Interactions of potassium vapor with reactor tubes made of different materials and their impacts on particulate matter emission during pulverized biomass combustion

During the combustion of biomass in drop-tube furnace (DTF) systems, the released alkali metal (e.g., potassium, K) inevitably reacts with reactor tube at high temperatures, affecting the experimental results on the emission of particulate matter with aerodynamic diameters of <10 μm (PM10). This study reports the interactions between K vapor and tube reactors made of silicon carbide, corundum, and mullite and their impacts on PM10 emission. Demineralized wood samples loaded with potassium chloride (KCl) or ion-exchanged K respectively were combusted in a DTF at 1300 °C under air or oxy-fuel atmosphere. Another series of experiments was conducted to collect and analyze the PM10 from the combustion of KCl-loaded wood, K-exchanged wood, and two typical biomass samples (cotton stalk and wheat straw) in the three reactor tubes under air atmosphere. Experimental results show that 4.1‒72.5% of K is retained in the three tubes when burning the KCl-loaded wood in air, and the combustion in oxy-fuel atmosphere slightly increases the K retention. For K-exchanged wood combustion in air, only 3.7‒23.6% of K is released from the reactor tubes. In all conditions, the reactivity of the reactor tubes with K vapor follows a sequence of mullite > corundum > silicon carbide. The retained K is unstable, 49.0‒64.8% of which can be re-released during polyvinyl chloride combustion. In addition, the results demonstrate that, compared with silicon carbide tube, the use of corundum and mullite tubes leads to a 16.2‒54.3% decrease in PM1 yields and a significant drop in fine mode peaks in PM10 during the combustion of biomass samples in air, while the PM1–10 yields and the coarse mode peaks remain largely unchanged. These are attributed to the enhanced retentions of alkali metals in corundum and mullite tubes, which reduce the yields of Na, K, and Cl in PM10, but has negligible effect on those of refractory elements such as Mg and Ca.

State prediction of distributed parameter systems based on multi-source spatiotemporal information

To predict the process states of nonlinear distributed parameter systems (DPS) using various process variables, a novel multi-source spatiotemporal modeling method is proposed in this paper to improve conventional temporal modeling methods. To tackle the challenge of modeling industrial process data of DPS with multi-source spatiotemporal characteristics, a multi-source spatiotemporal network (MS-STN) model, which is the integration of a long short-term memory (LSTM) network to extract information containing temporal characteristics and a convolutional long short-term memory (ConvLSTM) network to extract information containing spatiotemporal characteristics, is constructed. The comprehensive use of various process information is beneficial to improving the fitting accuracy of the model, and the generalization ability of the model can be enhanced at the same time. To prevent the gradient vanishing or gradient explosion in presenting complex spatiotemporal data due to the increase of network layers, a model structure of the residual network based on ConvLSTM is proposed in performing model training. Finally, the industrial ethylene oxychlorination reaction process is taken as an example. The experimental results of predicting the temperature of the reaction tube well demonstrate the effectiveness of the proposed method.