Tube Reactor Research Articles

A multifunctional tube reactor for catalytic oxidization of dioxins and its pilot-scale application

Dioxins are hazardous pollutants and catalytic oxidization is an effective technology for the treatment, and more works needs to set up the monolithic reactor to promote the industrial application. In this work, a catalyst formula was optimized and used to prepared tube reactor (Φ60 mm*1500 mm) for the pilot investigation. As a result, the powdered catalyst removed 90% of chlorobenzene (430 ppm) at 200 °C. 6-tube reactor removed 80% of chlorobenzene (330 ppm, 24 m3·h−1) at 200–210 °C in a lab-scale pilot experiment. 96-tube reactor removed 90% of real dioxins (0.26 ng TEG·Nm−3, 1000 m3·h−1) at 230 °C in an incineration plant. Simultaneously, the tube reactor removed 99% of NOx (78.9 mg·Nm−3) and particle matters with an average size of 6 µm. Acidic gases were removed by dry deacidification. Considering this, dioxins, NOx, acidic gases, and particle matters were removed at the same time. This result is in favor of simplifying and integrating flue-gas treatment system to reach “treating all pollutants by one equipment” concept.

TaqMan probe-based one-step multiplex real-time RT-PCR assay for the diagnosis of foot-and-mouth disease

Effective control and monitoring the spread of foot-and-mouth disease (FMD) relies upon rapid and accurate laboratory detection of FMD virus (FMDV). Therefore, in this report, a multiplex TaqMan probe-based one-step RT-qPCR assay simultaneously targeting FMDV 5′UTR and 3Dpol regions, and 18S rRNA housekeeping gene (as an internal control) in a single reaction tube was developed and evaluated. The multiplex one-step RT-qPCR assay specifically detected viral genome in both FMDV-infected cell culture suspensions and clinical samples collected from known-FMD infected animals. The assay could detect FMDV RNA in the archived FMDV cell culture isolates (n = 120) collected during the last two decades in India. In addition, the new assay could also detect viral RNA in the FMD suspected clinical samples (n = 740) collected from various field outbreaks. At a cut-off Ct-value of <38, the assay could detect at least 20 and 10 copies of FMDV 3Dpol and 5′UTR genes, respectively. Further, the multiplex RT-qPCR assay proved to be robust, showing an inter-assay co-efficient of variations ranging from 1.3% to 3.03% for FMDV-3Dpol gene target, and from 1.44% to 4.69% for 5′UTR gene target. In addition, it was found that the new assay could be used to detect viral genome in a variety of samples (epithelium, saliva, OPF, milk and blood) without any significance difference in the detection limit of the assay. Hence, the multiplex one-step RT-qPCR assay could be considered a valuable tool for the detection of FMDV in India.

Decomposition of Thermally Stable Fuel Using a Cerium-Modified Zeolite Catalyst and Endothermic Characteristics.

The increase in the speed of aircraft causes a thermal load in the system. A cooling system is needed to solve this. Proactively, research is being conducted to cool the thermal load through the endothermic reaction of aircraft fuel. The decomposition of thermally stable fuel was performed using a lanthanide-modified zeolite as a catalyst, which was coated onto metal foam and the inner wall of a tube reactor to confirm the endothermic characteristics of the catalytic decomposition reaction. When a cerium-modified zeolite was used, the heat sink was increased to 1100Btu/lb and showed excellent performance for the cracking reaction.

Partial hydrogenation of 1,3-butadiene over nickel with alumina and niobium supported catalysts

The hydrogenation of 1,3 butadiene (BD) is an important industrial process that is generally used to generate butenes and aromatics, which are important petrochemicals and constituents of transportation fuels. Ni-based catalysts have gained increasing interest in the academic community and industry because of their superior hydrogenation activity, ability to exist in multiple oxidation states and most importantly, affordability compared to the less-abundant precious metal catalysts. In this work, we explore the ability of alumina (Al2O3) and niobia (Nb2O5) as catalytic supports for Ni as the active metal since they have shown excellent potential for hydrogenation of alkenes. Specifically, we compare the metal-support interactions, which disperse Ni effectively throughout the catalyst surface, textural and pore parameters, Ni crystallite size, surface morphology, elemental composition, coke formation and tendencies of both catalysts through extensive characterization techniques such as H2-temperature programmed reduction (H2-TPR), N2-adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy combined with electron-dispersive spectra (SEM-EDS), and thermal analysis of the spent catalysts. Limited reports on the use of niobium oxides and alumina as supports for Ni in the partial hydrogenation of BD prompted us to explore this literature gap. The catalytic reactions were conducted using a quartz tube reactor between a temperature range of 50 and 400 °C at regular intervals of 50 °C under operating pressures of 1 atm. A comprehensive analysis of the products from the reaction was carried out using gas-chromatography with mass spectrometry (GC–MS) detector and corroborated these results with those from infrared spectroscopy (FTIR). Reaction mechanisms of aliphatic and aromatic product formation were proposed and verified with literature and our own characterization results. The tests on the spent catalysts also helped to reveal the extent of deactivation of the catalysts due to carbon deposition. Mechanisms of catalyst deactivation and nature of carbonaceous deposits were explored and elaborate scientific reasoning was provided as to why Ni/alumina showed better performance in terms of product yields and BD conversion. Ways to mitigate the harmful effects of coke formation and its deposition are also discussed. The novelty of our work is that a comprehensive comparison of the performance of Ni/alumina and Ni/niobia for hydrogenation of BD along with extensive discussions on coke formation, its chemical nature and proposed reaction chemistry based on obtained characterization results of the catalysts and the products of BD hydrogenation has not been done before for this system. In this way, we show the low-temperature conversion of BD represents an economically efficient and relatively simple method to convert toxic, carcinogenic and environmentally hazardous BD into high-value products using low-cost and chemically efficient catalysts.

Optimizations of the EA-IRMS system for δ15N analysis of trace nitrogen

The elemental analyzer-isotope ratio mass spectrometer (EA-IRMS) technique is widely utilized to measure the nitrogen isotope ratio (δ15N) in various environmental samples. However, this method has limitations when analyzing samples with low nitrogen content (e.g., soils, rocks and atmospheric deposition) due to significant sample dilution (>99%) before entering the ion source. To reduce sample size requirement and increase sensitivity, modifications can be made to the elemental analyzer and analytical conditions to transfer more sample gas to the ion source. In this study, we presented four modifications to the EA-IRMS instrument, including the reaction tube, water trap, gas chromatography (GC) column, and inlet splitter connected to ConFlo, along with the analytical conditions of the GC column, carrier gas flow rate, and split ratio for improving sensitivity. The results show that reducing the carrier gas flow rate from 80 to 30 mL/min increased the sensitivity of the EA-IRMS system by twofold. By increasing the split ratio from 3:2 to 3:1, the sensitivity increased from 2.32 Vs/μg N to 3.93 Vs/μg N. The optimized EA-IRMS has a sample size requirement of at least 12 μg N and a standard deviation of <0.2‰ for δ15N analysis. We found that the modifications of the GC column and water trap had a negligible influence on sample peak and measurement and thus were deemed unnecessary. The effective modifications in the study were reducing the carrier gas flow rate and increasing split ratio, which increased the concentration of the analyte gas per unit volume and more efficient sample transfer to the ion source. This upgraded method can provide crucial technical support for environmental samples with low nitrogen content.

Solar thermal reactor model for pyrolysis of waste plastic

ABSTRACT The ability to convert waste plastic into combustible liquids and gases using solar energy could help transform the problem of disposal of non-recyclable plastic into a valuable and environmentally responsible source of fuel. The purpose of this study is to propose a practical model for a compound parabolic trough solar thermal reactor for pyrolysis of waste plastic. The model integrates predictions of energy available from solar radiation (at a given location, time of day and time of year) with parabolic trough collector orientation and efficiency, a transient energy balance for an evacuated tube reactor and pyrolysis kinetics of waste plastic. The experimental setup used to test the model includes a pyranometer, a commercial solar collector consisting of a 60 cm long evacuated tube with a compound parabolic reflector and multi-channel data loggers to collect temperature, humidity and radiation data. The solar radiation sub-model was found to be in excellent agreement with clear-sky irradiance data collected using the pyranometer. Predictions of reactor temperature and reaction rate were found to be sensitive to the concentrator aperture area, solar irradiance, type of plastic (Arrhenius kinetics) and radiation properties of the evacuated tube reactor but relatively insensitive to humidity, wind velocity and terrestrial irradiance. The model shows that even on a small scale, favourable conditions for pyrolysis of waste plastic can be achieved within a solar reactor.

Fast pyrolysis of agricultural biomass in drop tube reactor for bio-oil production: Numerical calculations

Fast biomass pyrolysis is an effective method for bio-oil production and can be performed in fluidised beds, augers, and drop-tube reactors. In this study, the fast pyrolysis of agricultural biomass (oat and corn straw) in a drop-tube reactor was investigated by applying multiparameter analysis involving numerical calculations. The main motivation for this analysis was to determine the operating parameters for fast pyrolysis under which the highest bio-oil production was achieved. In this study, the following operating parameters were involved: pyrolysis temperature (500 – 700 °C), volume flow rate of the carrier gas (3 – 5 l/min), mass flow rate of the feedstock (10 – 30 g/h), and diameter of the particle (250 – 750 µm). The analysis was performed using numerical methods with the Euler-Lagrange multiphase theory in a 2D axisymmetric model. According to the numerical results, selection of a particle size of 500 µm, pyrolysis temperature of 500 °C, and nitrogen flow rate of 3 l/min allows obtaining 51.16% and 52.09% of bio-oil for oat straw and corn straw pyrolysis, respectively. The biomass mass load did not influence the final product yield. The numerical results were successfully confirmed by experimental investigations where experiments supplied 53.2% and 51.3% of bio-oil to oat straw and corn straw, respectively.

Reactivation strategies for nucleation-inhibited catalyst beds in continuously operated gas-release reactions from liquids

In reactions that release gaseous products from liquids, heterogeneous, porous catalysts can be in an active or nucleation-inhibited state as has recently been shown by our group for batch dehydrogenation reactions. This paper investigates this practically highly relevant phenomenon now in a continuous tube reactor for the example of liquid organic hydrogen carrier (LOHC) dehydrogenation. A mechanical stimulus, increase in reaction temperature or decrease in residence time reactivates the inhibited catalyst bed. Furthermore, the experimental results indicate that the dehydrogenation reaction turns into a hydrogenation reaction for thermodynamic reasons as the catalyst bed cools down. Hydrogenation is responsible for the consumption of the gas phase and thus a liquid filling of the pellets, which causes the nucleation-inhibition. Our work reveals new aspects of nucleation-inhibition on catalyst beds and provides insights into the efficient operation of heterogeneous catalytic gas release reactions in which this phenomenon occurs.

Thermodynamic and economic analysis of a novel thermoelectric-hydrogen co-generation system combining compressed air energy storage and chemical energy

With the adjustment of energy structure, the proportion of renewable energy is gradually increasing, and how to solve the problem of renewable energy consumption is becoming more and more prominent. Therefore, a novel thermoelectric-hydrogen co-generation system combining compressed air energy storage (CAES) and chemical energy (CE) is proposed. For energy storage, the system uses adiabatic compression with liquid piston to reduce the generation of compression heat, while using the generated compression heat to preheat the methanol. For energy release, the methanol is fed into the methanol steam reforming reactor (MSR) and the methanol decomposition reactor (MDR) in certain proportions for the hydrogen production reaction; the unreacted methanol and the carbon monoxide produced by the MDR are used as make-up heat for the reactors and the high-pressure air before the turbine, while the exhaust waste heat supplies heat to the customer. The thermodynamic, economic and environmental performances of the system were investigated separately by developing a mathematical model describing the system. The results show that under the design conditions, the system has an energy storage density of 12.00 kWh/m3, an energy efficiency of 88.47 %, an exergy efficiency of 77.04 %, a lifetime net present value of 59.20 M$, a payback period of 4 years, and a CO2 emission per unit of energy output of 227.85 kg/MWh. Increasing the thermostatic heat source temperature and increasing the reactor diameter and length increased the methanol conversion rate. Increasing heat exchange effectiveness of the heat exchanger and heat source temperature can all improve system thermodynamic and economic performance. The energy storage density, energy efficiency, net present value and profitability of the system varied parabolically with the reactor tube diameter. The system energy storage density had a maximum value of 12.03 kWh/m3 at a reactor diameter of 0.040 m.

Phosphorous extraction and heavy metal separation from sewage sludge ash by two-compartment electrodialysis in an upscaled tube reactor

Two-compartment electrodialytic extraction (2C-ED) is a one-step process for the simultaneous phosphorous extraction and separation of heavy metals from sewage sludge ash (SSA). The process is driven by an applied electric DC field, which can be supplied from renewable sources. The proof-of-concept of the method was conducted in small laboratory cells; however, upscaling to a continuous 2C-ED process, which additionally can treat SSA suspensions at a low liquid-to-solid (L:S) ratio, requires a new design. This paper presents such a new design. In principle, ED consists of two compartments separated by a cation exchange membrane. One compartment contains a suspension of SSA in water and the anode. A cathode is placed in the other compartment. Electrolysis at the anode acidifies the suspension causing the dissolution of phosphorous and heavy metals. The heavy metals are separated from the suspension by electromigration into the catholyte, whereas the dissolved phosphorous remains in the dispersion solution. In the new design, the SSA was suspended in a tube-shaped reactor with the cation exchange membrane covering the outside. The reactor was placed in a container with the catholyte. Periodically turning off the reactor kept SSA in suspension even at a low L:S ratio without corners and pockets where the SSA otherwise tends to settle. Five 2C-ED experiments were conducted with 1.5 to 3 kg SSA at varying currents and durations. Up to 89% P was extracted. The extracted P was concentrated in the dispersion solution of the SSA suspension, where the obtained P-related concentrations of heavy metals were far below the limiting values for spreading on agricultural land. The experiments underlined that treating the SSA in a suspension with a low L:S ratio is advantageous. A comparison to previous laboratory experiments in small cells treating 50 g SSA shows a significantly more efficient use of the applied current in the new reactor setup. Thus, the new reactor design for 2C-ED fulfilled the set criteria for the operation and did additionally result in a higher efficiency than the laboratory setups, i.e., the design can be the first step towards an upscaling.

Design and Analyses of Miniature, Submersible Annular Linear Induction Pump for Test Loops Supporting Development of Advanced Nuclear Reactors

A submersible annular linear induction pump (ALIP) design with an outer diameter of 66.8 mm with appropriate materials is developed for circulating molten lead and alkali liquid metals of sodium and sodium-potassium-78 (NaK-78) alloy in test loops at temperatures up to 500°C. These loops investigate the compatibility of these liquid coolants with nuclear fuel and structure materials to support the development of advanced, Generation IV nuclear reactors. The present ALIP, which employs high-temperature ceramic-insulated coil wires and Hiperco-50 center core and stators, fits in Type 316 stainless steel, 2.5-in. standard schedule 5 pipe. This pipe, considered for the riser tube of the Versatile Test Reactor (VTR) in-pile test cartridge loop, has an inner diameter of 68.8 mm permitting 1.0-mm radial clearance for the present ALIP. An improved equivalent circuit model (ECM) is developed to analyze the performance of the present ALIP design. The accuracy of the model predictions is successfully validated using reported experimental measurements by other investigators for a low liquid sodium flow ALIP at 200°C and 330°C. The improved ECM calculates the performance characteristics of the present ALIP design and investigates the effects of varying the terminal voltage, current frequency, winding wire diameter, center core length, width of the liquid flow annulus, and working fluid properties and temperature on the pump operation. For circulating molten lead, the calculated peak efficiency of the present ALIP design of 6.7% occurs at a flow rate of 9.5 kg/s and pumping pressure of 263 kPa. The calculated peak efficiency for circulating liquid sodium is much higher, 26.3%, and occurs at a lower flow rate of 2.2 kg/s but a higher pumping pressure of 364 kPa. The calculated peak efficiency for circulating NaK-78 (23%) is lower than for sodium and occurs at a lower flow rate and pumping pressure of 1.9 kg/s and 310 kPa, respectively.

Is monolithic configuration superior to random packing in a fixed bed reactor for CLC like processes?

In light of the geometric deficiencies and diffusion constraints of conventional packed-bed reactors, the potential application of monolithic configurations in fixed-bed reactors was explored using the structure-resolved CFD approach. This work delves into how geometric features of fixed beds influence flow patterns and related transport phenomena. To assess the performance of mass transfer and heterogeneous reactions in different configurations, we conducted simulations of fixed-bed chemical looping combustion (CLC) processes, in which a simplified model of non-catalytic gas-solid reactions is implemented to reduce the computational costs. Our findings highlight the importance of face contact between reaction tube and the monolithic structure, which effectively eliminates the inherent wall effects of random packing and enhances the radial heat conduction. More uniform geometry in the monolithic configuration naturally suppresses violent interstitial channeling flow in the random packing. Notably, the honeycomb configuration demonstrates an exceptionally low pressure drop, about two orders of magnitude smaller than that of the Raschig ring packing, and the designable monolithic configurations offers the potential to further reduce the pressure drop with enlarged voidage. Open-cell foams exhibit excellent convective and radial heat transport properties, promote homogeneous flow fields, and demonstrate superior performance in conjugate transport and heterogeneous reactions.

Intensification of aqueous mineralisation of CO2 with CaO containing industrial wastes in a modified airlift reactor

CO2 mineralisation is considered the safest storage medium for mitigating climate change. One of the challenges with the industrial demonstration of the mineralisation technology is reactor design. In the current study we demonstrate the use of draft tube based reactor for the mineralisation of CO2. The draft tube reactors show better performance as compared to the absence of draft tube at near ambient pressure for CO2 at different concentrations. The draft tube has been modified to increase the gas-liquid mass transfer rate by adding multi-orifice plates on top as well as increasing the solid precipitation in the reactor with a spiral flow arrangement at the bottom of the draft tube. At higher CO2 concentrations and near ambient pressures, the draft tube with modifications shows 2.5 fold enhancement in the overall rate as compared to draft tube without modifications. Additionally, at lower CO2 concentrations (i.e. near flue gas concentrations), the draft tube with modifications has better conversion capacity as compared to draft tube without modifications. This enhancement is due to the increased gas holdup and separation of solids in the draft tube with modifications. The precipitates obtained in the draft tube reactors show nanoparticles arranged in coral or mosaic arrangements as compared to the reactor without draft tube.

Drastic Microbial Count Reduction in Soy Milk Using Continuous Short-Wave Ultraviolet Treatments in a Tubular Annular Thin Film UV-C Reactor.

Vegetative cells of Listeria monocytogenes and Escherichia coli and spores of Bacillus subtilis and Aspergillus niger were inoculated in soy milk at an initial concentration of ≈5 log CFU/mL. Inoculated and control (non-inoculated) soy milk samples were submitted to three types of treatments using a tubular annular thin film short-wave ultraviolet (UV-C) reactor with 1 mm of layer thickness. Treatments applied depended on the flow rate and the number of entries to the reactor, with UV-C doses ranging from 20 to 160 J/mL. The number of entries into the reactor tube (NET) was established as the most determining parameter for the efficiency of the UV-C treatments. Conidiospores of A. niger were reported as the most resistant, followed by B. subtilis spores, while vegetative cells were the most sensible to UV-C, with Listeria monocytogenes being more sensible than Escherichia coli. Treatments of just 80 J/mL were needed to achieve a 5 log CFU/mL reduction of L. monocytogenes while 160 J/mL was necessary to achieve a similar reduction for A. niger spores.

Methane Pyrolysis in a Liquid Metal Bubble Column Reactor for CO2-Free Production of Hydrogen

In light of the growing interest in hydrogen as an energy carrier and reducing agent, various industries, including the iron and steel sector, are considering the increased adoption of hydrogen. To meet the rising demand in energy-intensive industries, the production of hydrogen must be significantly expanded and further developed. However, current hydrogen production heavily relies on fossil-fuel-based methods, resulting in a considerable environmental burden, with approximately 10 tons of CO2 emissions per ton of hydrogen. To address this challenge, methane pyrolysis offers a promising approach for producing clean hydrogen with reduced CO2 emissions. This process involves converting methane (CH4) into hydrogen and solid carbon, significantly lowering the carbon footprint. This work aims to enhance and broaden the understanding of methane pyrolysis in a liquid metal bubble column reactor (LMBCR) by utilizing an expanded and improved experimental setup based on the reactor concept previously proposed by authors from Montanuniversitaet in 2022 and 2023. The focus is on investigating the process parameters’ temperature and methane input rate with regard to their impact on methane conversion. The liquid metal temperature exhibits a strong influence, increasing methane conversion from 35% at 1150 °C to 74% at 1250 °C. In contrast, the effect of the methane flow rate remains relatively small in the investigated range. Moreover, an investigation is conducted to assess the impact of carbon layers covering the surface of the liquid metal column. Additionally, a comparative analysis between the LMBCR and a blank tube reactor (BTR) is presented.

Xylan fast pyrolysis: An experimental and modelling study of particle changes and volatiles release

Biomass char particles produced by pyrolysis may have different morphologies, which has important implications on burning mode, conversion rate and boiler efficiency. These features are difficult to address due to the complexity of biomass structure and pyrolysis reaction models.The present work reports preliminary results on the morphological changes and volatile release that solid particles of Xylan experience upon fast heating in a Drop Tube Reactor (DTR) and in a Heated Strip Reactor (HSR) in a range of temperature between 1100 and 1573 K under inert atmosphere with heating rate in the order of 103 K/s. Two different Xylan samples were chosen as representative of Hemicellulose in angiosperm biomass: xylooligosaccharide extracted from Beechwood (hardwood biomass) and from Corn Cob (herbaceous biomass).During the heatup phase, Xylan particles do not retain the original shape and morphology, neither in DTR nor in HSR experiments. In the early pyrolysis stage, Xylan particles melt and form viscous droplets. As devolatilization proceeds these droplets in the DTR evolve into highly viscous sponge-like particles with spherical shape, which swell and eventually shrink, ultimately producing highly porous spherical char particles.The experimental results are compared with the predictions obtained by the Bio-CPD Xylan pyrolysis model. The model is fairly able to calculate the pyrolysis yields in the DTR, but predicts unexpectedly low extent of metaplast formation. To explain the remarkable melting phenomena and morphological changes observed in the experiments, tuning of some CPD parameters and inclusion of mass transfer and pressure build-up within the particles might be necessary in future work.

A Rapid and Novel Multiplex PCR Assay for Simultaneous Detection of Multiple Viruses Associated with Bovine Gastroenteritis.

Bovine viral diarrheal virus (BVDV) and bovine coronavirus (BCoV) are prevalent viral infections in buffalo calves that result in significant economic losses globally. However, Bovine picobirnavirus (BPBV) Group I and II has been an emerging causes of gastrointestinal infection as has been detected with mixed of BVDV as well as BCV. To combat economic losses and viral infection, a rapid and innovative multiplex-PCR assay (M-PCR) was developed to simultaneously identify BVDV, BCV, and BPBV. The assay employed three primer pairs, each specific to a particular virus. Notably, the primers for BCV and BVDV, targeting the transmembrane (M) Mebus gene and 5'UTR genes, respectively, were self-designed. To validate the assay, 300 samples of buffalo calf feces were subjected to the standardized multiplex PCR. The results demonstrated that 54 (18%) samples tested positive for multiple viruses, with 16.67% samples infected by BVDV, 0.9% by BCoV, and 0.13% by BPBV, as detected by the M-PCR assay. In summary, this developed assay is characterized by high specificity, sensitivity, throughput, and speed, enabling the simultaneous detection of the three viruses in a single reaction tube. Consequently, it holds potential for epidemiological investigations. It is worth noting that, to the best of our knowledge, this is the first reported multiplex assay for the worldwide detection of BVDV, BCoV, and BPBV. This novel assay promises to aid in the detection of mixed infections in the gastrointestinal tract.

Influence of reactor composition on the thermal decomposition of perfluorooctanesulfonic acid (PFOS)

Various reactor tubes (quartz, stainless steel 316 and stainless steel 253 MA) were used to examine their influence on the thermal decomposition of perfluorooctanesulfonic acid (PFOS) between 400 and 1000 °C. Using helium as a carrier gas, with the addition of 100 – 300 ppm of PFOS to the feed gas, the influence of the reactor materials on PFOS decomposition was studied. The quartz reactor led to a notable reduction in the concentration of HF and substantial quantities of SiF4 were observed. Stainless steel 316 produced C2F4, HF, COF2 and SO2 as its primary products up to 800 °C. However, at temperatures above 800 °C, near quantitative removal of SO2 from the gas phase was observed, with the concomitant formation of a blue molybdenum sulfur complex. Stainless steel 253 MA, the composition of which contains over 1% Si produced substantial quantities of SiF4 but no significant decrease in the gas phase concentration of HF. Environmental implicationThis research underscores the significant role of reactor material in the thermal treatment of PFAS, a globally widespread and enduring environmental contaminant. The findings have direct implications for the optimization of thermal treatment strategies aimed at mitigating PFAS contamination. The insight into how different reactor materials interact with PFOS during thermal treatment expands our understanding of potential destruction methods. This knowledge is crucial in the development of effective, sustainable strategies for managing persistent environmental pollutants like PFAS.

Three-Dimensional-Printed Vortex Tube Reactor for Continuous Flow Synthesis of Polyglycolic Acid Nanoparticles with High Productivity.

Polyglycolic acid (PGA) nanoparticles show promise in biomedical applications due to their exceptional biocompatibility and biodegradability. These nanoparticles can be readily modified, facilitating targeted drug delivery and promoting specific interactions with diseased tissues or cells, including imaging agents and theranostic approaches. Their potential to advance precision medicine and personalized treatments is evident. However, conventional methods such as emulsification solvent evaporation via batch synthesis or tubular reactors via flow chemistry have limitations in terms of nanoparticle properties, productivity, and scalability. To overcome these limitations, this study focuses on the design and development of a 3D-printed vortex tube reactor for the continuous synthesis of PGA nanoparticles using flow chemistry. Computer-aided design (CAD) and the design of experiments (DoE) optimize the reactor design, and computational fluid dynamics simulations (CFD) evaluate the mixing index (MI) and Reynolds (Re) expression. The optimized reactor design was fabricated using fused deposition modeling (FDM) with polypropylene (PP) as the polymer. Dispersion experiments validate the optimization process and investigate the impact of input flow parameters. PGA nanoparticles were synthesized and characterized for size and polydispersity index (PDI). The results demonstrate the feasibility of using a 3D-printed vortex tube reactor for the continuous synthesis of PGA nanoparticles through flow chemistry and highlight the importance of reactor design in nanoparticle production. The CFD results of the optimized reactor design showed homogeneous mixing across a wide range of flow rates with increasing Reynolds expression. The residence time distribution (RTD) results confirmed that increasing the flow rate in the 3D-printed vortex tube reactor system reduced the dispersion variance in the tracer. Both experiments demonstrated improved mixing efficiency and productivity compared to traditional tubular reactors. The study also revealed that the total flow rate had a significant impact on the size and polydispersity index of the formulated PGA nanoparticle, with the optimal total flow rate at 104.46 mL/min, leading to smaller nanoparticles and a lower polydispersity index. Additionally, increasing the aqueous-to-organic volumetric ratio had a significant effect on the reduced particle size of the PGA nanoparticles. Overall, this study provides insights into the use of 3D-printed vortex tube reactors for the continuous synthesis of PGA nanoparticles and underscores the importance of reactor design and flow parameters in PGA nanoparticle formulation.

Design and optimization of hydrogen production system model for dimethyl ether self-heating steam reforming

Hydrogen, as a clean energy source, has been widely used in the automotive industry. However, considering the difficulties of hydrogen storage and transportation, the in-situ production process has received increasing attention. In this paper, a hydrogen production system for dimethyl ether self-heating steam reforming is proposed, using a spiral tube reactor in which the oxidation of dimethyl ether occurs in the spiral tube, and the exothermic oxidation of dimethyl ether is used to provide heat for the dimethyl ether steam reforming hydrogen production reaction. A numerical model of the hydrogen production system for dimethyl ether self-heating reforming is developed, the model is simulated and analyzed, the accuracy of the model is verified through experiments, the influence of various parameters and on the system is analyzed, and the system is optimized. The results show that the proposed system can solve the problems of high energy consumption, low hydrogen yield and difficult reaction control faced by traditional autothermal reforming hydrogen production, and the system can achieve 87.79% dimethyl ether conversion rate, 84.94% hydrogen yield and 85.94% system thermal efficiency.