For particulate matter pollution, a multiple force fields coupled purification system is proposed. Among them, the filtration mechanisms of the granular bed in the coupled system constituted the key to achieving efficient fine-particle separation (<5 μm). In order to ensure stable operation of the purification system, continuous and efficient cleaning regeneration of the filter particles in the bed are required. The spouted regeneration is utilized for cleaning and transportation at present, while severe abrasion phenomenon is observed and the bed filter particle size material continue to decrease in the high velocity transportation. Hence, a novel regenerator for binary particles separation with significant size difference is proposed. By introducing airflow entrainment mechanism and vibration screen mechanism, the mixtures including the dusts and filter particles can be separated efficiently in a novel micro-airflow vibrating regenerator (MAVR). Experiments confirmed that the regeneration efficiency of the micro-airflow vibrating regenerator exceeded 85.98%, which was higher than the 84.71% achieved with conventional spouted regeneration. Additionally, the efficiency remained relatively stable. The median size of the dust particles separated by MAVR ranged from 2.18 to 2.49 μm. Moreover, this novel regenerator exhibited a very low pressure drop below 100 Pa and better energy saving characteristic compared with the conventional riser-spouted regeneration(3–7 kPa). The proposed regeneration model yielded accurate predictions for regeneration efficiency, with its calculated results showing strong consistency against experimental data. This model proved valuable for performance assessment and subsequent engineering design.

A cold-model circulating fluidized bed is used to investigate gas–solid flow behavior in tapered-in risers with inclined angles of 0.3°, 0.5°, and 0.7°, with a conventional cylindrical riser as a reference. Local solids holdup and particle velocity are measured using optical fiber probes. The tapered-in risers exhibit a distinct S-shaped axial solids holdup profile and a continuously decreasing particle velocity along the axial direction, in contrast to the typical C-shaped solids holdup profile and bottom particle-acceleration region observed in the cylindrical riser. The bottom section of the tapered-in riser remains in a dilute fast-transport state because of the high local gas velocity, whereas the middle section becomes the main flow-transition region. In this region, the decrease in local gas velocity caused by cross-sectional expansion is not followed immediately by particle deceleration, leading to near-wall accumulation, back-mixing, local internal circulation, and the highest solids holdup. Radially, the cylindrical riser shows a core–annulus structure that weakens after the bottom acceleration region, while the tapered-in risers develop stronger core–annulus structures in the middle and upper sections. A mechanistic analysis based on the Kutta–Joukowski (K-J) force further indicates that the radial non-uniformity of local solids holdup is closely related to the K-J force acting on particles. The K-J force analysis helps explain the development of near-wall solids accumulation and core–annulus structures, and its magnitude is jointly affected by slip velocity and particle-velocity gradient. Mesoscale analysis further shows that near-wall clusters in the middle and upper sections of the tapered-in riser are denser and more persistent, although their occurrence frequency is lower. These results clarify the geometry-induced flow restructuring in tapered-in risers and provide hydrodynamic guidance for the design of tapered-in riser–turbulent bed coupled reactors for PDH.

The performance of a trickle bed reactor (TBR) is primarily determined by liquid spreading in the reactor. The radial spreading will be weakened under the uniform liquid inlet conditions. To elucidate liquid spreading characteristics, particularly radial dispersion, the non-uniform liquid inlet condition is investigated in trickle bed reactor. It is found that the liquid spreading characteristics are mainly determined by the governing forces on the liquid. Therefore, dimensionless numbers including the Weber number (We) and the AB number (AB) are introduced to quantify the impact of governing forces. The results show that gravity is the primary governing force under the experiment conditions. Nevertheless, inertial forces and capillary forces show gradually more significant effects with enhanced gas-liquid flow rates and aspect ratios. Gravity and gas-phase inertial forces promote axial liquid spreading, while capillary forces and liquid-phase inertial forces promote radial liquid spreading. Finally, an empirical correlation considering the governing forces is established to predict the liquid spreading uniformity.

Pressure drop is one of the key factors affecting the performance of trickle bed reactors. The particle characteristics and flow regime have a significant influence on the pressure drop. A pseudo-two-dimensional trickle bed reactor is constructed to investigate the effects of particle wettability and shape on pressure drop under different flow regimes. Experimental results indicate that particle wettability is beneficial for increasing liquid holdup, thereby increasing pressure drop. Moreover, cylindrical particles can increase the number of contact points between particles, which leads to an increased liquid holdup, and thus an increased pressure drop. A correction parameter including the effects of relative capillary force, particle shape, and flow regime is developed to modify the Holub pressure drop model. The modified model demonstrates a satisfactory prediction for the pressure drop in trickle bed reactors.

The gas-solid contact efficiency in fluidized bed chemical vapor deposition (FDCVD) for silicon‑carbon anode production is constrained by inadequate fluidization of porous carbon deposition substrate particles (Geldart C) at low gas velocities. Unlike typical Geldart C particles, flowability tests indicated that porous carbon ultrafine particles exhibit excellent floodability. Therefore, their flow regime transition behavior under high-velocity fluidization was investigated. Electrical capacitance tomography characterized solids holdup distribution, and predictive models for axial solids holdup and the critical solids circulation flux sustaining fast fluidization were established. By analyzing pressure fluctuation signals, the Apparent Fluid Fluctuation Index (AFFI) and Pulsation Intensity Matching Index (PIMI) were proposed to quantify the gas-solid mixing intensity and its matching with the solids holdup distribution. Compared with turbulent fluidization, fast fluidization showed a comparable AFFI but a 22.91% lower PIMI, indicating effective and more uniform gas-solid mixing. Therefore, fast fluidization provides a more suitable operating regime for FDCVD.

Traditional swirl vane demisters are widely used in industrial wet flue gas desulfurization (WFGD) systems. However, they suffer from high operational pressure drop, severe wall erosion, and a sharp decline in demisting efficiency at high gas velocities due to the breakup and re-entrainment of wall liquid film under strong gas shear, making it difficult to meet increasingly stringent ultra-low emission requirements. To address these problems, this paper designs a novel guide vane demister with the comprehensive optimization objectives of high efficiency, low resistance, and erosion resistance. Based on the Eulerian-Lagrangian multiphase flow framework, a gas-liquid two-phase flow numerical model is established. The SST k-ω turbulence model is adopted to describe the turbulent gas flow, the Discrete Phase Model (DPM) is used to track droplet trajectories, and the Discrete Random Walk Model (DRWM) is coupled to account for the effect of turbulent fluctuations on droplet dispersion behavior. The droplet motion equation incorporates the coupled effects of drag force, centrifugal force, and gravity. Using the experimental data of a swirl vane demister from the literature as a benchmark, the pressure drop and demisting efficiency under different inlet gas velocities (1.76–3.49 m/s) are compared to validate the accuracy of the numerical model. On this basis, the structural design of the arc-shaped guide vane demister is completed, with key geometric parameters including a cylinder diameter D0=284 mm, a central column diameter Di=142 mm, a vane outlet angle α=45°, and five guide vanes. Three-dimensional numerical simulations are then performed, and a systematic performance comparison with the traditional swirl vane demister is conducted from multiple dimensions, including velocity field, pressure field, turbulent kinetic energy, and droplet concentration distribution.The model validation results show good agreement between the simulated pressure drop, demisting efficiency and the experimental values, with relative errors within 5%, confirming the reliability of the numerical model. Flow field analysis reveals that a stable "Rankine vortex" structure is formed inside the guide vane demister, with the tangential velocity exhibiting a typical "low at the center, high near the wall" distribution. Compared with the traditional swirl vane demister: (1) the peak tangential velocity decreases from approximately 7.5 m/s to approximately 4 m/s, a reduction of about 40%, and the velocity distribution is more uniform with more gradual axial decay, significantly reducing the impact energy of droplets on the wall and the risk of erosion; (2) the operational pressure drop is reduced by 30%–40% across the entire simulated gas velocity range, with substantially decreased flow resistance; (3) the demisting efficiency is consistently higher than that of the traditional swirl vane demister, reaching 100% when the inlet gas velocity exceeds 2.78 m/s, achieving complete droplet removal.Owing to its streamlined geometry, the guide vane demister effectively eliminates the large vortex dead zone on the leeward side of the vanes and reduces local flow resistance, providing a sustained and stable centrifugal force field. While maintaining high-efficiency gas-liquid separation, it significantly reduces operational energy consumption and wall erosion risk, successfully achieving the comprehensive performance optimization characterized by "high demisting efficiency, low operational energy consumption, and low wall erosion risk." The findings of this study reveal the flow field evolution and droplet separation mechanisms of the guide vane demister, providing a reliable theoretical basis for the innovative design and engineering application of demisters for industrial flue gas purification.

Iron-Chromium Flow Batteries (ICFBs) are attractive for large-scale energy storage due to their low-cost and abundant raw materials, yet their commercialization is hindered by the sluggish Cr3+/Cr2+ redox kinetics. Herein, we develop a heterojunction-modified graphite felt electrode (Sn/SnOx@GF) via thermal annealing of a tin-terephthalate (Sn-BDC) metal-organic framework precursor. The resulting electrode has uniformly dispersed Sn/SnOx nanocatalyst particles on the surface of the graphite fiber, which provide abundant active sites and yield a rate constant (k0 = 1.015 x 10-4 cm s-1) with fast kinetics, comparable to that of the Fe3+/Fe2+ redox couple. The ICFB with Sn/SnOx@GF electrode achieved an energy efficiency of 80.5 % at a high current density of 160 mA cm-2, far surpassing pristine graphite felt. The unexpected electrochemical performance benefits from the presence of Sn/SnO heterointerfaces, in which metallic Sn enhances Cr3+ adsorption, and SnO accelerates electron transfer. The unique electronic synergy at these heterointerfaces, where Sn boosts s and p orbital occupancy of SnO near the Fermi level, significantly improves the electron transfer capability and accelerates the Cr3+/Cr2+ redox kinetics. Additionally, the modified electrode exhibits excellent cycling stability over 100 cycles. This work provides a viable strategy for high-performance ICFB electrodes and offers insights into heterointerface engineering for large-scale energy storage.

In this study, to explore the influence of nozzle jets on the gas-solid flow behavior in a downer reactor, different forms of jets are introduced in the fully developed section of the downer reactor. Numerical simulations are conducted to examine the effects of different jet forms (upward and downward-inclined jets) and jet angles on the gas-solid flow behavior. The Kutta-Joukowski theorem, which was originally developed in aerodynamics, is adopted in this study to analyze lateral forces in the gas-solid flow system. The results show that after the introduction of a jet, the radial particle velocity distribution in the downer reactor becomes more uniform. Compared to downward inclined jets, upward jets, which interact counter-currently with the particle flow, are more effective in increasing the particle concentration within the downer reactor. The solid holdup at the reactor center in the dense-phase region is 1 to 6.6 times higher in the presence of jets than in the absence of jets at the same gas flow rate. For both upward and downward jets, the 60 degrees axial nozzle-wall angle shows the best center concentration enhancement effect. Additionally, the larger the axial nozzle-wall angle is, the easier it is for particles to recover to the uniform distribution.

In industrial gas-solid heterogeneous catalytic systems, diffusion and intrinsic kinetics are always coupled. Quantitatively decoupling the effects of diffusion and intrinsic reactions is very important to design advanced catalyst and develop efficient industrial reactor. For propane dehydrogenation, a new mathematical model is proposed to decouple the apparent reaction rate into an unsteady diffusion fitting parameter (kc) and an intrinsic rate constant (kr). The kc is decoupled by intrinsic and apparent kinetic experiments and utilized to quantitatively correlate the gas velocity with the intensity of external diffusion. In the prediction of propane dehydrogenation, the base value of kc is 7.29 x 10-11 m & sdot;s- 1 at a gas velocity of 0.066 m/s, which is positively correlated with the 0.5 power of the gas velocity. The model demonstrates high prediction accuracy of external diffusion effects across various gas velocities.

Fluidized beds are widely studied for solar thermochemical energy storage due to their uniform gas-solids distribution and high-efficient gas-solids contact. In this study, a multi-stage fluidized bed is designed to achieve the uniform gas-solids fluidization across multiple stages. A two-fluid model is employed to investigate the hydrodynamics. The distributions of pressure and solids holdup reveal the presence of both dense and dilute phase regions within the bed, with corresponding sections observed in the down-comer. In the bed, gas carries particles upward, demonstrating typical fluidized bed behavior, while in the down-comer, particles entrain gas downward, exhibiting a dense-phase conveying flow state under negative pressure difference. An increase in gas velocity enhances the storage capacity of the upper bed but reduces that of the middle and lower beds due to decreased conveying capacity in the down-comer. Although the higher gas velocity increases the apparent storage capacity in the down-comer, it ultimately leads to lower conveying capacity. To ensure stable operation, it is recommended that the superficial gas velocity be maintained below 0.15 m/s.

In the multistage feeding strategy for oxidative coupling of methane (OCM), local flow characteristics within the feedstock zone significantly influence hydrodynamics and reactor performance. Detailed analysis of these flow behaviors is essential for optimizing the reactor design and enhancing the overall process efficiency. This work utilizes computational fluid dynamics (CFD) to investigate the local flow characteristics within the feedstock zone of a downward nozzle structure. The feedstock zone is divided into three distinct regions: (1) the centerline, (2) the entrainment zone above the nozzle, and (3) the momentum influence zone below the nozzle. In the entrainment zone, a counterclockwise vortex is observed near the left sidewall, resulting from the axial-radial velocity gradient. In the momentum influence zone, a region of high oxygen concentration is identified. To quantitatively analyze the flow behavior, a momentum influence zone model is established to predict the range of momentum effects. Additionally, the effects of nozzle inclination angle and jet velocity on gas-solid flow dynamics are investigated. The results demonstrate that an increase in the inclination angle leads to a reduction in the ranges of both the entrainment zone and the momentum influence zone. Conversely, an increase in gas velocity leads to the expansion of the entrainment zone and the momentum influence zone. These findings provide critical insights into the optimization of reactor design and operational parameters for enhanced process performance.

Micro-fluidized beds significantly enhance mass and heat transfer efficiency in gas-liquid-solid catalytic reaction systems due to their high specific surface area characteristics. However, scale effects often induce bubble coalescence and promote slugging tendencies. To address these limitations, this study utilizes a microporous distributor with apertures smaller than the particle size to compartmentalize conventional miniaturized fluidized beds, accordingly constructing a novel miniaturized confined fluidized bed. Furthermore, by employing a triple analysis framework integrating power spectral density, wavelet decomposition, and K-means clustering, the bubble dynamics within the confined gas-liquid-solid micro-fluidized bed are quantitatively characterized. Based on the extracted bubble dynamics characteristics, thresholds for classing bubble motion states in the confined micro-fluidized bed are summarized. Additionally, K-means clustering is utilized to objectively analyze geometric and operational parameters on bubble dynamics features, enabling the partitioning of operating gas-velocity regimes corresponding to different bubble motion states without subjective human influence.

The regenerated exhaust gas was reutilized to configure a centrifugation-filtration coupled purification system (CFCPS), aiming to achieve a closed-loop gas purification process. It can be foreseen that this optimization will bring objective economic savings without sacrificing separation efficiency. A series of typical tests were carried out to analyze the influence of the reutilized exhaust gas on the pressure drop and the separation efficiency. Compared with the purification system without the reutilized exhaust gas, the purifier exhibited optimal performance at Q = 800 m3/h, RV = 25%, and Ci = 30.24 g/m3. Notably, the median size of outlet particles decreased from 1.67 & micro;m to 0.82-1.04 & micro;m and the size range was narrowed when the exhaust gas was recycled. Moreover, the grade efficiency of the dust particles below 3 & micro;m was improved significantly with reutilization. The study indicates that the exhaust gas reutilization is an effective means to solve particle pollution, and further measurements are needed. (c) 2026 Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The three-dimensional flow field in a novel cyclone-granular bed coupled separator was discussed experimentally with a five-hole probe system. The airflow behaviors in the annular space, separation space, and central outlet were addressed. Several significant phenomena (the squeezing effect, the top flow loop, and the rectification effect) were observed and analyzed. By comparing the three-dimensional velocity distribution in the coupled separator with different structure parameters (the coupling space index, rc=0.37/0.44), the combined effect between the two efficient gas purifiers was demonstrated and the importance of the tangential velocity was clarified. For this purpose, the equations for the tangential velocity at four circumferential positions were fitted using regression analysis with a wide array of experimental data and effectively characterized prior experimental outcomes.

The instantaneous signals recorded with the optical fiber probe (OFP) directly reflect the hydrodynamic behaviors in fluidized beds. A new data-processing method is put forward to calculate the threshold voltage that is used to discern the bubble phase and emulsion phase. It is found that the threshold voltage is not only related to the flow pattern but also to the color of the used particles. Then the data-processing programs including the Fast Fourier filter have been developed for determining the flow characteristics such as the bubble/particle velocity, bubble/agglomerations chord length, etc. By comparing them with other different methods, the suitability of the proposed method for quantifying the hydrodynamic behaviors in bubble/turbulent fluidized beds is verified. Finally, this method is employed to analyze the characteristics of bubbles, agglomerations and particles in a gas-solid fluidized bed. It is found that the hydrodynamic behaviors of bubbling beds and turbulent beds have significant differences.

By large-scale cold mold experiments, pressure pulsation signals within the jet influence zone of riser reactor are processed by using Hilbert-Huang analysis (HHT) in this study. Effects of different jet forms and operating conditions on the intrinsic mode function (IMF) energy and Hilbert-Huang spectrum are compared. Results show that the IMF energy and Hilbert-Huang spectrum of pressure pulsation signals show significant differences under the influence of upward and downward jets. Moreover, the change of jet velocity will also lead to significant changes in IMF energy and Hilbert-Huang spectrum. Among them, energy values and energy proportions corresponding to high-frequency pressure pulsations show a good correlation with the jet velocity. On this basis, energy value and energy proportion data in the high frequency range of the original pressure signal are clustered and analyzed by using the K-means clustering algorithm. Based on clustering results, the jet influence zone of riser can be defined into three regions. From partitioning results, it is found that the introduction of downward inclined jets could effectively improve the gas-solid mixing in the feed injection zone of riser.

Methanol to olefins (MTO) plays a crucial role to transform non-oil resources into light olefins. Combined with the kinetics of MTO reaction process, a high-speed loop reactor (HSLR) is explored. The solids hydrodynamics including the uniformity distribution, fluidization quality, backmixing and carryover are systematically analyzed in detail. Moreover, the gas-solid hydrodynamics in the HSLR are coupled with the MTO reaction kinetics, and the methanol conversion and yields of light olefins are both predicted and compared in the HSLR and free fluidized bed (FFB). The results demonstrate that the particles distribute more uniform in the different regions of HSLR than that of FFB and the overall fluidization quality of particles is high in the HSLR. The overall non-uniformity index in the HSLR varies from 0.1 to 0.18 kPa and that in the FFB changes from 0.2 to 0.35 kPa when the superficial gas velocity is 1.03 m/s and the solids circulation flux equals to 90.9 kg/(m2 s). Meanwhile, the ratio of solids backmixing and carryover in the HSLR are both lower than that in the FFB. Finally, the hydrodynamics in HSLR are coupled with the five-lumped reaction kinetics for MTO. Based on the coupled model, it is predicted that both the methanol conversion and the yields of light olefins in the HSLR are higher than that in the FFB. The maximum difference between the methanol conversion and the light olefin yields in the HSLR and that in the FFB is 6.2 % and 0.000803 mol/L when the superficial gas velocity Ug is 0.87 m/s, which demonstrates the superiority of HSLR for MTO reaction.

In petrochemical units, particularly in fluid catalytic cracking (FCC), coupled reactors have the potential to both increase the target product yields and reduce equipment investments. In this study, the mixing and flow characteristics of binary particles with a significant size difference are investigated in a coupled fluidized bed. The influence of the initial blending ratio on the fluidization performance and the spatial distributions of binary particles are scrutinized. Empirical models for predicting the binary particle distributions are proposed. Besides, the viscous shear force caused by bubbles is analyzed to explain the mixing mechanism of particles. A viewpoint is proposed that binary particles have the possibility of dispersion between the bubble phase and the emulsion phase. The results indicate that the blending ratio plays a crucial role in the fluidization performance, the physical properties of the mixed particles with ratios bounded by 0.7 are significantly different. It tends to be disadvantageous if introducing too many coarse particles, but it is essential for coupled fluidized bed reactors.

In the feed injection zone of a multiphase fluidized bed reactor, nonuniform distribution exists due to the introduction of feed nozzle jets and circulating catalyst, which ultimately have an impact on the performance of the reactor. The transient sectional nonuniformity index (TSNI) is proposed as a new index to quantify the nonuniformity of solid distribution in both radial and circumferential dimensions at the same time, based on the transient solids holdup data in the feed zone. The temporal and spatial distributions of TSNI can more accurately reflect the changes in the real-time gas-solid distribution uniformity of the cross-sections and the efficiency of gas-solid contact in the feed injection zone. The feed injection zone can be divided into three regions according to the characteristics of TSNI: the bubble-influenced zone, the jet-influenced zone, and the acceleration zone. According to the numerical simulation results, it was analyzed that TSNI is highly correlated with operating conditions, such as nozzle gas velocity and catalyst circulation rate.