Fluidized Bed Research Articles

Deep learning assisted characterization of bubble behavior in a gas-solid fluidized bed with binary particle mixtures

Gas-solid fluidized beds are widely applied as chemical reactors, and the fluidization quality in the bed is closely related to bubble behavior. Digital image processing is a commonly used non-invasive method for bubble behavior analysis, but it is usually constrained by experimental conditions such as lighting, making identification of bubble and emulsion phases still challenging. Herein, deep learning is applied in this study to optimize traditional digital image processing techniques. By evaluating different deep learning models (FCN, DeepLab V3, U-Net), rapid and accurate identification and segmentation of bubble images can be achieved, and the U-Net model performs best, achieving an identification accuracy of 99.05 %. Further application of U-Net to analyze bubble behavior demonstrates that deep learning methods enable efficient and accurate identification of bubbles and real-time analysis of bubble behavior, highlighting the significant potential application of deep learning in the field of complex hydrodynamics in fluidized beds.

Spatiotemporal delivery of multiple components of rhubarb-astragalus formula for the sysnergistic treatment of renal fibrosis.

Rhubarb (Rheum palmatum L.) and astragalus (Radix astragali) find widespread used in clinical formulations for treating chronic kidney disease (CKD). Notably, the key active components, total rhubarb anthraquinone (TRA) and total astragalus saponin (TAS), exhibit superiority over rhubarb and astragalus in terms of their clear composition, stability, quality control, small dosage, and efficacy for disease treatment. Additionally, astragalus polysaccharides (APS) significantly contribute to the treatment of renal fibrosis by modulating the gut microbiota. However, due to differences in the biopharmaceutical properties of these components, achieving synergistic effects remains challenging. This study aims to develop combined pellets (CPs) and evaluate the potential effect on unilateral ureteral obstruction (UUO)-induced renal fibrosis. The CPs pellets were obtained by combining TRA/TAS-loaded SNEDDS pellets and APS-loaded pellets, prepared using the fluidized bed coating process. The prepared pellets underwent evaluation for morphology, bulk density, hardness, and flowing property. Moreover, the in vitro release of the payloads was evaluated with the CHP Type I method. Furthermore, the unilateral ureteral obstruction (UUO) model was utilized to investigate the potential effects of CPs pellets on renal fibrosis and their contribution to gut microbiota modulation. The ex-vivo study demonstrated that the developed CPs pellets not only improved the dissolution of TRA and TAS but also delivered TRA/TAS and APS spatiotemporally to the appropriate site along the gastrointestinal tract. In an animal model of renal fibrosis (UUO rats), oral administration of the CPs ameliorated kidney histological pathology, reduced collagen deposition, and decreased the levels of inflammatory cytokines. The CPs also restored the disturbed gut microbiota induced by UUO surgery and protected the intestinal barrier. The developed CPs pellets represent a promising strategy for efficiently delivering active components in traditional Chinese medicine formulas, offering an effective approach for treating CKD.

The Dispersion-Strengthening Effect of TiN Nanoparticles Evoked by Ex Situ Nitridation of Gas-Atomized, NiCu-Based Alloy 400 in Fluidized Bed Reactor for Laser Powder Bed Fusion

Throughout recent years, the implementation of nanoparticles into the microstructure of additively manufactured (AM) parts has gained great attention in the material science community. The dispersion strengthening (DS) effect achieved leads to a substantial improvement in the mechanical properties of the alloy used. In this work, an ex situ approach of powder conditioning prior to the AM process as per a newly developed fluidized bed reactor (FBR) was applied to a titanium-enriched variant of the NiCu-based Alloy 400. Powders were investigated before and after FBR exposure, and it was found that the conditioning led to a significant increase in the TiN formation along grain boundaries. Manufactured to parts via laser-based powder bed fusion of metals (PBF-LB/M), the ex situ FBR approach not only revealed a superior microstructure compared to unconditioned parts but also with respect to a recently introduced in situ approach based on a gas atomization reaction synthesis (GARS). A substantially higher number of nanoparticles formed along cell walls and enabled an effective suppression of dislocation movement, resulting in excellent tensile, creep, and fatigue properties, even at elevated temperatures up to 750 °C. Such outstanding properties have never been documented for AM-processed Alloy 400, which is why the demonstrated FBR ex situ conditioning marks a promising modification route for future alloy systems.

A universal drag model for liquid-solid fluidization: Experiment, data-driven modeling, CFD modeling and simulation

Various industrial applications are performed in liquid-solid fluidized beds where drag force plays a significant role in affecting the expansion characteristics of granular-bed, and then determines the mass/heat transfer performance. This study employs dimensionless learning data-driven modeling method, which is derived from the principle of dimensional invariance, to automatically discover the relationship between the drag coefficient and hydraulic dimensionless numbers from the liquid-solid fluidization data. It is found that the Fr number (=ul2/gds) also plays important role in improving the prediction accuracy of drag model except for Re number (=dsulρl/μl). The proposed data-driven modeling method has desired robustness, and the yielded drag model can be applicable to other liquid-solid systems, such as water-polystyrene spheres and water-coal particles, although it is derived from the fluidization of spherical glass beads in rising tap-water. The proposed drag model can also provide good CFD simulation results that agree very well with the experiment data with the relative error less than 5 %.

HANDS-ON FLUIDIZED BED CLASSROOM IMPLEMENTATION AND ASSESSMENT

In this study we examined the first-time use of a miniaturized fluidized bed module in a chemical engineering classroom. Learning activities were developed to foster learning at the higher levels of Bloom's taxonomy and within the ICAP framework to provide interactive, constructive, and active engagement to promote a deeper understanding of concepts. A hands-on activity facilitated by a desktop-scale fluidized bed and reinforcing printed worksheet materials was deployed within a 50-min class to encourage student engagement. Results from module performance tests compare well to predictions based on theoretical models suggesting this tool can effectively demonstrate fundamental concepts related to pressure loss in a packed bed, minimum fluidization velocity, constant pressure drop in a fluidized bed, bed expansion and repacking below a top screen. Pre- and Posttests 1 and 2 show student learning was significantly improved after pre-homework and the hands-on activity compared to the learning after the lecture alone. Student responses to two open-ended questions on Pre- and Posttests 1 and 2 allowed us to identify persisting student misconceptions about packed and fluidized beds. Suggestions for future work to repair these misconceptions are included in this study. Tweetable AbstractA hands-on fluidized bed learning tool enabling visualization of packed and fluidized beds in a chemical engineering classroom, and associated impacts on conceptual learning and student engagement.

Kinetics, catalyst design, and hydrodynamic analysis in Fischer–Tropsch synthesis: Fixed Bed vs Fluidized Bed Reactors

While fixed beds maximize contacting between the fluid and solid phase, commercial processes operate with fluidized beds for highly exothermic reactions, like Fischer–Tropsch (FT), to maximize heat transfer thereby minimizing catalyst sintering and deactivtion. However, conversion is lower due to gulf-streaming and poorer gas-solids contacting. In experimental reactors (<10mm) gulf-streaming is negligible and gas-solids contacting is excellent as bubbles are small. Here, we measure CO conversion over 3 FT catalysts—Fe/Ce/SiO2-K, Cu, Fe/Zr/SiO2-K, Cu, Fe/Catalox-K, Cu—across the same reactor operating in the fluidized bed and fixed bed regime. Flow rates were increased up to a maximum of 5 times the minimum fluidization velocity (Umf). The reactor operated at 2MPa, with a H2/CO molar ratio of 2, and 275°C≤T≤325°C. The average CO conversion was higher in the fixed bed but temperature control was more difficult, which could account for some of the differences. The highest ▪ selectivity (80% to 84%) was with the Fe/Catalox-K, Cu at 275°C, 2 to 4×Umf, in the fixed bed reactor. A first order reaction model characterized CO conversion well (R2>0.91) for the Fe-Catalox and Fe-Zr catalysts with activation energies >70kJmol−1. Conversion was essentially independent of temperature for the Fe-Ce composition in both the fixed bed and fluidized bed. BET surface area decreased 22% to 52% after the reaction. XRD analysis after the reaction revealed a 4% to 10% decrease in crystallinity, along with the presence of various Fe carbide compounds. Post-reaction SEM-EDS images indicated particle agglomeration and carbon deposition on the catalyst surface. Despite these morphological changes, the impact on CO conversion seemed minimal. Residence time distribution tests confirmed that gas was essentially in plug flow for both the fixed bed and fluidized bed configurations.

Numerical Investigation into Gas-Solid Fluidized Bed Reactors for Activating the Iron-based Fischer-Tropsch Synthesis Catalyst

Abstract The present work conducted experimental and computational fluid dynamics simulation studies on the hydrodynamic characteristics of gas-solid fluidized bed reactors for activating the iron-based Fischer-Tropsch synthesis catalyst. In order to provide reliable guidance for the design and scale-up of the reactor, the present study applied experimental data from a pilot fluidized bed device to verify the accuracy of the drag force model used in the two-fluid model and further used the validated drag force model to simulate an industrial-scale fluidized bed activation reactor. It was found that the bubbling-EMMS drag model can accurately simulate the pilot-scale fluidized bed in the flow regimes ranging from bubbling to turbulent fluidization. Simulation studies on the industrial-scale fluidized bed activation reactor showed that the reactor was in a turbulent fluidization regime under the designed operating gas velocity, with high gas-solid dispersion efficiency, reasonable utilization of reactor space, and low gas-solid separation load.

Continuous near-equilibrium operation and model validation of a pilot-scale thermochemical energy storage reactor using CaO/Ca(OH)2

Thermochemical energy storage using the material system CaO/Ca(OH)2 is regarded as one of the most promising technologies for application temperatures between 400 °Cand600 °C. However, there is still a lack of information concerning the transfer of laboratory results to industrially-relevant conditions. This study addresses this research gap and provides data for a continuously operated pilot-scale fluidized-bed storage reactor (257 mm diameter, up to 31L fluidized bed volume maximal 700 °C and 6barg). The reactor is operated near the thermodynamic equilibrium at varying space times of the storage material (250–400 µm). The bed height is maintained at 390 mm during continuous operation. The results indicate good fluidization quality at steady-state operation for up to 9 h. Based on the results, a CSTR-type reactor model is proposed and validated, giving good results in predicting the fluidized bed’s steady-state conversion and temperature. The model is based on material and fluidization properties, such as the fluidized beds porosity, that are measured in dependence of temperature and superficial gas velocity. The simulation results indicate that the heat transfer characteristics are crucial for adequate storage power.

Towards cleaner energy: An innovative model to minimize NOx emissions in chemical looping and CO2 capture technologies

The urgent global challenges of climate change and environmental issues have catalyzed the development of CO2-capture-ready technologies incorporating fluidization, such as fluidized bed (FB) and circulating fluidized bed (CFB) combustion under oxy-fuel conditions, chemical looping combustion (CLC), chemical looping with oxygen uncoupling (CLOU), in-situ gasification chemical looping combustion (iG-CLC), and calcium (or carbonate) looping (CaL) systems. While these technologies have the potential to reduce CO2 emissions significantly, the persistent presence of nitrogen oxides (NOx = NO + NO2) as pollutants remains a critical environmental concern.This paper introduces a comprehensive fuzzy logic-based model for predicting NOx emissions (FuzzyNOx model) from solid fuel combustion in fluidized beds of chemical looping systems. This innovative model takes into account a wide range of operating parameters, including fuel type, fuel particle size, fuel moisture content, air/fuel ratio, and temperature. It also explores advanced coal and biomass combustion modes, including air-firing, oxyfuel, iG-CLC, and CLOU. Furthermore, it delves into the intricacies of two distinct facilities: the 5 kWth dual-fluidized bed Chemical-Looping-Combustion of Solid-Fuels (DFB-CLC-SF) facility at Czestochowa University of Technology, Poland, and the calcium looping dual-fluidized bed (CaL DFB) facility at Niigata University, Japan.Bituminous coal, semi-anthracite, and wood chips are utilized as fuels. Moreover, three various oxygen carriers (OCs) for chemical looping combustion were employed, namely ilmenite, copper oxide (60 % wt.) supported by carbonate waste from ore flotation, and copper oxide (60 % wt.) supported by ilmenite (20 % wt.) and fly ash. Bituminous coal, semi-anthracite, and wood chips are utilized as fuels.The developed knowledge-based fuzzyNOx model allows the optimization of operating parameters to reduce NOx emissions from CO2 capture technologies.

Modeling of bed-to-wall heat transfer coefficient in fluidized adsorption bed by gene expression programming approach

Adsorption cooling and desalination methods with adsorption chillers (AC) are promising in energy technologies. However, the low-performance coefficient and bulkiness of traditional packed-bed ACs, primarily due to the high voidage of the sorbent beds leading to low heat transfer coefficients, pose significant challenges. Despite numerous attempts, a practical solution to this problem is yet to be found.In response to this challenge, we propose a novel approach: a fluidized adsorbent bed instead of the traditional packed bed. We also introduce gene expression programming (GEP) as an innovative artificial intelligence (AI) method for modeling the bed-to-wall heat transfer coefficient in the adsorption bed. Our study includes calculations and model validation for a heat transfer adsorption bed reactor designed for low-pressure adsorption processes. The fluidizing agent of the adsorbent bed was water vapor generated in the evaporator. Silica gel was used as the parent adsorption material in our tests. The heat transfer coefficient was successfully validated and determined through experiments and estimated using the formulated (b-t-wHTc) meta-model. The data evaluated by the model aligns well with the experimental results. Our calculations demonstrate that the GEP-based model accurately predicts the heat transfer coefficient and is suitable for analyzing the fluidized adsorption bed reactor.The outlined studies serve as a benchmark for subsequent simulations of the intensified heat transfer adsorption bed reactor, as they are integral to project No. 2018/29/B/ST8/00442, titled “Research on sorption process intensification methods in modified construction of adsorbent beds,” supported by the National Science Center in Poland.

A CFD and experimental study of hydrodynamic and heat transfer behavior in ribbed fluidized beds

Abstract The study focuses on enhancing the performance of fluidized bed systems, which are widely used in industrial processes requiring efficient heat and mass transfer. By integrating ribs at angles of 135, 150, and 165° on the riser wall, the research assesses their impact on hydrodynamic behavior and heat transfer using CFD simulations. The simulations, confirmed through experimental data, revealed that the 150° ribbed model outperforms others by improving particle mixing and achieving the highest heat transfer coefficient. The investigation also covered static pressure, solid volume fraction, and particle velocities at different bed heights (30, 60, 90, and 120 mm), showing that ribbed models significantly enhance turbulence and particle distribution, with the 150° ribs providing a balance between dynamic mixing and stable flow.

Acoustic emission and machine learning algorithms for particle size analysis in gas-solid fluidized bed reactors

In this work, a combination of an acoustic emission (AE) technique and a machine learning (ML) algorithm (Random Forest (RF) and Gradient Boosting Regressor (GBR)) is developed to characterize the particle size distribution in gas-solid fluidized bed reactors. A theoretical approach to explain the generation of acoustic emission signal in gas-solid flows is presented. An AE signal is generated in gas-solid fluidized beds due to the collision and friction between fluidized particles as well as between particles and the bed inner wall. The generated AE signal is in the form of an elastic wave with frequencies >100 KHz and it propagates through the gas-solid mixture. An inversion algorithm is used to extract the information about the particle size starting from the energy of the AE signal. The advantages of this AE technique are that it is a cheap, sensitive, non-intrusive, radiation-free, suitable for on-line measurements. Combining this AE technique with ML algorithms is beneficial for applications to industrial settings, reducing the cost of signal post-processing. Experiments were conducted in a pseudo-2D flat fluidized bed with four glass bead samples, with sizes ranging from 100 μm to 710 μm. AE signals were recorded with a sampling frequency of 5 MHz. The AE signal post-processing and data preparation for the ML process are explained. For the ML process, the AE frequency, AE energy and particle collision velocity data sets were divided into training (60%), cross-validation (20%) and test sets (20%). Two ensemble ML approaches, namely Random Forest and Gradient Boosting Regressor, are applied to predict particle sizes based on the AE signal features. The combination of these two models results in a coefficient of determination (R2) value greater than 0.9504.

Experimental Study of Agglomeration Formation during Co-Combustion of Coal and Palm Kernel Shell in Fluidized Bed

Abstract Co-combustion of biomass and coal in Indonesia power plants are a key element of the path towards achieving net-zero emissions. However, introducing biomass into a coal-boiler furnace may pose operational challenges. Therefore, this study aims to assess the potential of agglomeration when mixing biomass with a fluidized bed boiler. Complementation simulation tests were conducted by combining coal with various fractions of palm kernel shell (PKS) in a furnace capacity of 5kWth maintained at 850°C within an hour. The initial fuel was 100% coal, gradually increasing the biomass mixture by 5%, 10%, 15%, 20%, and 25%. The results indicated that de-fluidization occurred at 25% of the biomass mixture and to prevent agglomeration, the temperature of the bed was kept below 850°C. The agglomeration test of coal and PKS mixtures was successfully performed in a 5kW lab-scale facility, and the result will be useful for predicting agglomeration phenomena in power plants.

Numerical investigation of turbulent mass transfer processes in turbulent fluidized bed by computational mass transfer

Turbulent fluidized bed possesses a distinct advantage over bubbling fluidized bed in high solids contact efficiency and thus exerts great potential in applications to many industrial processes. Simulation for fluidization of fluid catalytic cracking (FCC) particles and the catalytic reaction of ozone decomposition in turbulent fluidized bed is conducted using the Eulerian–Eulerian approach, where the recently developed two-equation turbulent (TET) model is introduced to describe the turbulent mass diffusion. The energy minimization multi-scale (EMMS) drag model and the kinetic theory of granular flow (KTGF) are adopted to describe gas–particles interaction and particle–particle interaction respectively. The TET model features the rigorous closure for the turbulent mass transfer equations and thus enables more reliable simulation. With this model, distributions of ozone concentration and gas–particles two-phase velocity as well as volume fraction are obtained and compared against experimental data. The average absolute relative deviation for the simulated ozone concentration is 9.67% which confirms the validity of the proposed model. Moreover, it is found that the transition velocity from bubbling fluidization to turbulent fluidization for FCC particles is about 0.5 m·s–1 which is consistent with experimental observation.

Continuous self-circulating up-flow granular sludge fluidized bed process treating low-strength real municipal wastewater at high hydraulic loads

Conditions conducive to aerobic granular sludge (AGS) growth and maintenance are very difficult to realize in continuous-flow biological treatment processes. This study conducted a continuous-flow self-circulating up-flow granular sludge fluidized bed (Zier process) treating real urban wastewater approximately one year. The substantial self-circulating multiple times (RSCMT, 8–15 times) and up-flow velocity (8–15 m/h) generated by aeration, the only power equipment in Zier process, facilitated pollutant removal, particle granulation and stabilization. With hydraulic retention time of 5 h, RSCMT of 9.3–14.4 times and chemical oxygen demand (COD)/total nitrogen (TN) ratio of 5.9 ± 1.0, the effluent COD, ammonia nitrogen and TN were 28.6 ± 7.7, 1.1 ± 1.2, and 13.3 ± 1.7 mg/L, respectively. The median particle size was 150–250 μm and effluent suspended solids concentration was 33.4 ± 14.5 mg/L. It is unnecessary to set up sludge reflux which simplifies the subsequent mud-water separation facilities. The Zier process provides a new process structure for implementation of continuous-flow AGS process.

Unique seismic and eruption precursors to the 1996 and ongoing magmatic eruptions of Popocatépetl: Coupled and fluidized bed events

We describe three unique types of seismicity at Popocatépetl volcano that accompanied the initial vent-clearing eruptive activity in December 1994 through the eruption of the first two domes in 1996. We identify and describe two types of coupled events, 1) spasmodic burst coupled events, a burst of volcano tectonic (VT) events coupled with a large eruptive explosion (21 December 1994 and 5 March 1996), and 2) explosion-couplet coupled events, a pair of events with a deeper first event and whose second event correlates with a small gas emission or explosion. Explosion-couplets occurred with the onset of magmatic ash dominated eruptions and their properties are very useful for forecasting magmatic eruptions at Popocatépetl volcano. Measurable quantities including the time between the first and second phase, daily numbers of events, and the amplitude ratio between the second and first phase systematically changed as the first two domes approached the surface between March and June 1996. Interevent times decreased from many tens of seconds to a few seconds, while amplitude ratios increased from about 2 to 10 or more. Event numbers increased prior to and during initial dome extrusion. These changes were used to forecast the eruption of the first two domes. We also report on another unusual type of low frequency seismicity that accompanied emissions called fluidized bed events. Fluidized bed events occurred following the initial eruption on 21 December 1994, beginning mid-January 1995, when SO2 emissions were initially elevated, and the conduit was open. Fluidized bed events began to wane in late March through the end of May 1995 as did SO2 emissions. Consistent gas, visual and seismic observations by Centro Nacional de Prevención de Desastres (CENAPRED) enabled the direct correlation of the gas, magma, and seismic phenomena.

Power production characteristics of binary particles pulsed anaerobic fluidized bed microbial fuel cell

A novel binary particulate pulsating anaerobic fluidized bed microbial fuel cell (BPFB-MFC) was designed and constructed in order to improve the efficiency of low-grade energy conversion in sewage. The effects of pulsed liquid flow rate and bed filling rate on the electricity production performance and effluent treatment characteristics of the BPFB-MFC were investigated experimentally. The results showed that when the pulsed liquid flow was u=1.95sin(π/3)t cm·s-1 and when the bed materials in the anode chamber consisted of 10% bed height activated carbon particles and 10% bed height ceramic particles, the highest voltage produced was 519.7mV, the highest power density was 587.5mW·m-2, and the lowest internal resistance was 171.2Ω, which was the optimal experimental working condition. It was found that the electricity production performance and effluent treatment efficiency of the mixed particles system were better than those of a system with single particles. This work held promise of promoting the industrialization of MFC.

Strategizing internals’ geometry to improve resilience of marinized bubbling fluidized beds to roll-induced maldistribution

Marinized bubbling fluidized beds show potential for reducing ship exhaust emissions, but their performance is hampered by the unstable marine environment, which affects their hydrodynamic stability. This study addresses the challenge of roll-induced maldistribution by testing different geometric strategies of bed internals to improve operational resilience. Direct visualization techniques (including digital image analysis and particle image velocimetry) were used to investigate the hydrodynamics and stability of bubbling fluidized beds under various configurations in pseudo-2D vertical, inclined, and rolling conditions. Internal designs, such as rhombic and herringbone patterns, and vertical baffle arrays, significantly shield the beds from gas maldistribution and provide stable fluidization comparable to conventional aboveground setups. The rhombic internals achieved up to 93% of the stability of classical vertical configurations without internals, while the herringbone reached 60 % and the vertical baffles reached 55 %. These configurations mitigate hydrodynamic fluctuations due to oscillations, improving operational reliability to effectively reduce emissions in marine environments.

Influence of computational parcel resolution on hydrodynamics and performance of reacting fluidized bed reactors

The Eulerian-Lagrangian computational models are critical for understanding gas-phase processes and addressing engineering challenges, yet their numerical accuracy in reactive gas-solid fluidized beds remains a concern. This work utilizes the multiphase particle-in-cell (MP-PIC) scheme to assess the impact of parcel number on the hydrodynamics and reaction predictions in the fluid catalytic cracking (FCC) catalyst regeneration process. By employing the energy-minimization multi-scale model for bubbling and turbulent flow regimes, the MP-PIC simulations closely match experimental solids concentration profiles. We developed and analyzed different parcel resolutions: 9.5×10³, 2.0×10⁴, 1.0×10⁵, 2.2×10⁵, 1.1×10⁶ in bubbling fluidized beds (BFB), and 6.5×10³, 1.3×10⁴, 7.1×10⁴, 1.4×10⁵, 6.8×10⁵ in turbulent fluidized beds (TFB). The findings reveal a significant sensitivity of coke combustion efficiency, flue gas evolution, and temperature to parcel resolution in BFB, attributable to mesoscale activities, with less impact observed in TFB. The study highlights the essential balance between the accuracy of Lagrangian particle configuration and computational costs.

Experimental Study on the Mass Flow Rate Characteristics of a Fluidized Bed Powder Fuel Feeding System

In this study, a fluidized bed powder fuel feeding system that controls flow using the principle of two-phase gas-solid choking is proposed. Experiments based on real-time weighing methods were conducted to explore the flow rate characteristics under various total pressure and throttle-orifice area conditions. The experimental results showed that as the total pressure increased, the powder flow rate first decreased and then increased. To achieve the same increase in powder mass flow rate by altering the pressure, fine powder requires a greater pressure increment than coarse powder. A choked flow formula based on the gas-solid two-phase nonequilibrium model was derived, for investigating the influence of these two factors on the powder flow rate. Compared with the experimental results, this formula predicts the powder flow rates within a 20 % error margin. This model provides more precise guidance for engineering designs. The studied powder fuel-feeding system was connected to a powder engine, and hot-fire tests were conducted. The results showed that the pressure fluctuation in the powder engine combustion chamber did not exceed 2.5 %, confirming the feasibility and stability of the powder supply in the fluidized bed powder fuel feeding system.