Influence of filler characteristics on particle removal in fluid catalytic cracking slurry under an alternating electric field

The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS particles.In this study,the electric field distribution of a separation unit consisting of packed spheres under an alternating electric field is simulated,and the movement mechanism of catalyst particles is analysed.An"effective contact point"model is derived to predict the adsorption of filler contact points on catalyst particles under the alternating electric field,and the model is validated by simulations and experiments.The numerical calculation and experimental results indicate that the electrical properties of the filler spheres,the filler angleθ,and the frequency f of the alternating electric field affect the adsorption of catalyst particles.As the frequency of the electric field increases,the particle removal efficiency of the high-conductivity filler(silicon carbide)increases and then settles,and the separation efficiency of the low-conductivity filler(glass,zirconia)is not sensitive to the change in electric field frequency.

Particle Removal Mechanism of High Volume Fraction SiCp/Al Composites by Single Diamond Grit Tool

Particle removal mechanism was presented during machining particle SiC/Al composites with diamond grinding tool. The relevant removal modes and their mechanisms were discussed considering the impact and squeezing effect of diamond grit on the SiC particle. The experimental results show that the aluminum matrix has larger plastic deformation, so the aluminum mixed with the surplus SiC particles is cut from the surface. The SiC particles can be removed in multiple ways, such as broken/fractured, micro cracks, shearing and pulled out, etc. More particles removed by shearing, and less particles removed by fractured during material removal progress can produce a better machined surface.

Particle size distribution and removal by a chemical-biological flocculation process

The particle characterization from the influent and effluent of a chemical-biological flocculation （CBF） process was studied with a laser diffraction device. Water samples from a chemically enhanced primary treatment （CEPT） process and a primary sediment tank process were also analyzed for comparison. The results showed that CBF process was not only effective for both the big size particles and small size particles removal, but also the best particle removal process in the three processes. The results also indicated that CBF process was superior to CEPT process in the heavy metals removal. The high and non-selective removal for heavy metals might be closely related to its strong ability to eliminate small particles. Samples from different locations in CBF reactors showed that small particles were easier to aggregate into big ones and those disrupted flocs could properly flocculate again along CBF reactor because of the biological flocculation.

Preparation of Clay/Biochar Composite Adsorption Particle and Performance for Ammonia Nitrogen Removal from Aqueous Solution

This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.

Enhanced removal of ultra fi ne particles from kerosene combustion using a dielectric barrier discharge reactor packed with porous alumina balls

Ultrafine particles(UFPs)are harmful to human beings,and their effective removal from the environment is an urgent necessity.In this study,a dielectric barrier discharge(DBD)reactor packed with porous alumina(PA)balls driven by a pulse power supply was developed to remove the UFPs(ranging from 20 to 100 nm)from the exhaust gases of kerosene combustion.Five types of DBD reactors were established to evaluate the effect of plasma catalysis on the removal efficiency of UFPs.The influences of gasflow rate,peak voltage and pulse frequency of different reactors on UFPs removal were investigated.It was found that a high total UFP removal of 91.4%can be achieved in the DBD reactor entirely packed with PA balls.The results can be attributed to the enhanced charge effect of the UFPs with PA balls in the discharge space.The UFP removals by diffusion deposition and electrostatic attraction were further calculated,indicating that particle charging is vital to achieve high removal efficiency for UFPs.

Removal of Particles by ICRF Cleaning in HT-7 Superconducting Tokamak

The ICRF (Ion Cyclotron Range Frequency) cleaning technique has been used as a routine wall cleaning method in the HT-7 superconducting tokamak. In a wide range of toroidal field, the removal rate of residual gas by ICRF cleaning was about twenty times higher than that of glow discharge cleaning (GDC). At different gas pressure and RF power levels, the ICRF cleaning is studied carefully. A good impurity cleaning effect and a very high hydrogen removal rate were obtained. The removal rate of hydrogen by 5 kW ICRF cleaning achieved was 1.6 × 10-5 Tirr.1/s.And the relationships among pressure P, outgassing rate Q, atomic layers L absorbed on surface and the cleaning mode were discussed briefly.

Effect of surfactant on removal of particle contamination on Si wafers in ULSI

The adsorption mechanism of particle on the surface of silicon wafer after polishing or grinding whose surface force field is very strong was discussed, and the removal method of particle was studied. Particle is deposited on the wafer surface by interactions, mainly including the Van der Waals forces and static forces. In order to suppress particles depositing on the wafer surface, it is essential that the wafer surface and the particles should have the same polarity of the zeta potential. According to colloid chemistry and lots of experiments, this can be achieved by adding surfactants. Nonionic complex surfactant was used as megasonic cleaning solution, and the adsorptive state of particle on Si wafers was effectively controlled. The efficiency and effect of megasonic particle removal is greatly improved. A perfect result is also obtained in wafer cleaning.

Numerical Study on Hydrodynamic Forces for Micro Particle Detachment by Droplet Impact

This paper presents the results of a numerical investigation of micro-sized particle removal by droplet impact. Computational fluid dynamics simulation is used to calculate the flow distribution of droplet impact on a flat surface. The hydrodynamic forces exerted on the particle are then computed. Key factors controlling particle removal are discussed. Both hydrophilic and hydrophobic surfaces are considered. The flow distributions,especially the front edge expanding upon impact at microscale,strongly depend on surface wettability. The associated hydrodynamic forces on the particles vary accordingly. In addition, the impact on a dry surface can produce higher removal efficiency than that on a wet surface. Under the same impact conditions, the drag force exerted on a particle residing on a dry surface can be three orders of magnitudes larger than on a wet surface. Improving droplet impact velocity is more effective than improving droplet size.

Mechanism of ultrasonic-pulse electrochemical compound machining based on particles

The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.

Effect of Ventilation Strategies on Particle Distribution in a Two-Zone Ventilated Room

A computational fluid dynamic （ CFD ） analysis of air movement and aerosol particle transport in a two-zone ventilated room with an inter-zonal opening is presented to study the impact of ventilation strategies and size of the opening on indoor particle dispersion and concentration distribution. The comparisons of average particle concentrations in both zones between the computations and the experiments from the literature are generally satisfactory and acceptable. The combined effects of sizes of the opening and the inlet and outlet locations （three different strategies） are simulated and discussed. The results show that ventilation strategy and size of the opening influence the particle removal rate in zone 1. The removal rate is decreased when the air supply system is changed from the tap-inlet to the bottom-inlet configuration. The top-inlet system obtains a better particle deposition in zone I than the bottom-inlet configuration. However, the particle concentration at breathing level is lower for bottomsupply system than for top-supply. Decreasing the size of interzonal opening increases the particle deposition rate in zone 1 only for the top.supply system, especially for coarse particles.

Intravenous-Accelerated Saline Particles to Unblock Partially Clogged Blood Vessels Using a Microcontroller

This research assesses the speed of saline fluid in vein vessels using venipuncture medical kit as well as DC submersive pumps that are being controlled by a microcontroller. The microcontroller is monitored and governed using a software IDE interface installed on a powerful laptop. Saline solution is being pumped through a medical syringe at variable speeds up to a maximum of 18.39 cm/second to the vein. The novel technique in this research is the usage of two pumps called Pump 1 and Pump 2. Pump 1 is used to physically model the flow of “blood” in human vein and the second pump (Pump 2) is used to generate the accelerated saline particles that are used to break the yellow grease that is placed on the inside of the vein’s wall. A tiny brush is briefly dipped into yellow grease, and then it is used to place one layer (one turn) of yellow grease on the inside of the vein’s wall, and then this procedure is repeated to place consecutive layers of yellow grease onto the inside of the wall of the vein vessel using a tiny brush. It was found that accelerated saline particles can in fact destroy fats that are built up inside the veins’ walls.

Numerical simulation and experimental study of gas cyclone–liquid jet separator for fine particle separation

To address the shortcomings of existing particulate matter trapping technology,especially the low separation efficiency of fine particles,herein,a novel gas cyclone-liquid jet separator was developed to research fine particle trapping.First,numerical simulation methods were used to investigate the flow field characteristics and dust removal efficiency of the separator under different working conditions,and to determined suitable experimental conditions for subsequent dust removal experiments.Afterward,the separation efficiency of the separator against five kinds of common particles,including g-C_(3)N_(4),TiO_(2),SiC,talc,and SiO_(2),was experimentally studied.A maximum separation efficiency of 99.48%was achieved for particles larger than 13.1μm,and 96.55%efficiency was achieved for particles larger than 2μm.The best crushing atomization effect was achieved for the separator when uGwas 10 m·s^(-1)and uLwas 3 m·s^(-1),while the best separation effect was achieved when uGwas 10 m·s^(-1)and uLwas 3.75 m·s^(-1).Studies have shown that the gas cyclone-liquid jet separator has excellent applicability in the separation of fine particles.

Controlling fine particles in flue gas from lead-zinc smelting by plasma technology

With the aim of controlling the problem of fine particles in the flue gas of lead-zinc smelting,a low-temperature plasma-electrocoagulation and electric bag composite dedusting experimental platform was designed by combining electrocoagulation and electric bag composite dust removal technology based on the research of low-temperature plasma technology.Firstly,the properties of fine particles in flue gas from lead-zinc smelting were analyzed,and the effects of input voltage,filter wind speed,dust concentration,and pulse-jet ash-cleaning cycle on the dust collection efficiency of the integrated device were studied.Then,the energy efficiency of the integrated technology was analyzed,and the control mechanism of the fine particles was revealed.The experimental results show that the integrated technology of low-temperature plasma-electrocoagulation and electric bag composite dust removal achieves a fine particle removal efficiency of more than 99.99%and the energy consumption per unit mass of the dust is only 0.008 k W·h/g.The integrated technology has broad application prospects and farreaching practical significance for the lead-zinc smelting industry to achieve ultra-low emission targets for flue gas and achieve energy-saving and emission reduction effects.

Adaptable "bubble particles" prepared by green aqueous phase reshaping for completely removing odor

Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers.However,current micro/nano particles loading approaches are often hindered by issues such as uneven distribution,unsatisfactory stability and complicate procedure.In this work,we present an aqueous phase reshaping method that only utilizes the moisture to fabricate the"bubble particles",which could perfectly cater to the topography of the substrate.The green preparation of bubble particles adopts an absolutely zero-pollution method,realizing the firm loading of particles on the substrate.Integrating the preparation and loading of particles overcomes the traditional complicate process,while the aqueous phase reshaping ensures uniform and firm loading of the"bubble particles"onto the substrate.Our mechanism demonstrates a significant enhancement in the interface relation after aqueous phase reshaping,with a 121-fold increase in contact surface area achieved by reducing the height by 1μm.Furthermore,we explore for the first time the influence of the nature of the receiving substrate on the interface morphology of particles during electrostatic spraying,which has important guiding significance for the interface relationship of electrostatic spraying and even electrostatic spinning materials.We also screen out the natural antibacterial essential oil linalool as the effective specialized antibacterial agent,which can specifically inhibit the odor-producing Proteus in urine,with an antibacterial rate of up to 100%.Taken together,this simple,ecofriendly method for fabricating functional materials with optimal interface stability appears highly promising for use in various products formed by electrostatic spraying/spinning.

Improving the removal of fine particles by chemical agglomeration during the limestone-gypsum wet flue gas desulfurization process

Coal-fired power plants are considered a major source of fine particle emissions in China.Aimed to improve the removal efficiency of fine particles during the limestone-gypsum wet flue gas desulfurization(WFGD) process, a novel technology using chemical agglomeration to abate the emission of fine particles is presented herein. The relationship between fine particle emission and the proportion of fine particles in the desulfurization slurry was studied.Additionally, the influence of chemical agglomeration on fine particle size distribution, both in the flue gas and slurry was experimentally investigated. When chemical agglomeration agents were added to the desulfurization slurry, the fine particle removal performance as well as the effects of the operation parameters was also explored via the simulated experimental facility.The results revealed that the fine particles in both the desulfurization slurry and flue gas were significantly enlarged after the addition of the agglomeration agents. This was more marked in the submicron particles. Thus, the proportion of fine particles(< 10 μm) in the slurry decreased from 31.1% to 22.6%. An increase in the desulfurization slurry temperature and liquid-to-gas ratio aided the reduction in fine particle emission. Moreover, the addition of an agglomeration agent in the slurry did not affect the desulfurization efficiency of the desulfurization tower and even promoted the WFGD process. Thus, the proposed chemical agglomeration technique reduced the fine particle emission of the WFGD system by ～30%, while a desulfurization efficiency >90% was maintained.

Agglomeration and removal characteristics of fine particles from coal combustion under different turbulent flow fields

Turbulent agglomeration is a promising pretreatment technology for improving the removal of fine particles in industrial flue gas,which can improve the particle removal effect of dust removal equipment safely and economically.However,due to the complexity of turbulence mechanisms,the relationship between turbulent flow fields and the agglomeration of fine particles is not known with precision,resulting a weak promotion effect for particle removal with this pretreatment technology.In this work,three kinds of turbulent agglomerators were constructed to investigate the agglomeration and removal characteristics of fine particles under different turbulent flow fields.The results demonstrated that the turbulent agglomerator with small-scale and three-dimensional vortexes in the flow field had the best effect in improving the agglomeration and removal of fine particles.Two kinds of agglomeration modes in turbulent agglomeration were proposed,one being agglomeration between fine particles in the vortex area,and the other the capture of fine particles by coarse particles.Furthermore,the motion trajectory,relative velocity and residence time of fine particles of different sizes in different flow fields were calculated by numerical simulation to investigate the interaction mechanism of particle agglomeration and turbulent flow fields.The results showed that a flow field with smallscale and three-dimensional vortexes can reduce the Stokes number(StK) and the relative velocity of particles of different sizes,and extend their residence time in a turbulent flow field,so as to obtain a better agglomeration effect for fine particles.

Non-ionic surfactant on particles removal in post-CMP cleaning

The effect of a non-ionic surfactant on particles removal in post-CMP cleaning was investigated. By changing the concentration of the non-ionic surfactant, a series of experiments were performed on the 12 inch Cu pattern wafers in order to determine the best cleaning results. Then the effect of the surfactant on the reduction of defects and the removal of particles was discussed in this paper. What is more, the negative effect of a non-ionic surfactant was also discussed. Based on the experiment results, it is concluded that the non-ionic surfactant could cause good and ill effects at different concentrations in the post-CMP cleaning process. This understanding will serve as a guide to how much surfactant should be added in order to achieve excellent cleaning performance.

Material removal mechanism of copper chemical mechanical polishing with different particle sizes based on quasi-continuum method

In this paper,the material removal mechanism of copper chemical mechanical polishing was studied by the quasicontinuum method that integrated molecular dynamics and the finite element method.By analyzing the abrasive process of different particle sizes on single crystal copper,we investigated the internal material deformation,the formation of chips,the stress distribution,and the change of cutting force.Results showed that shear band deformation was generated along the cutting direction at approximately 45° inside the workpiece material.The deformation was accompanied by dislocations and sliding phenomena in the shear band region.Smaller abrasive particle size led to poor quality of the workpiece,while a larger particle size led to better quality.However,larger particle size resulted in greater plastic deformation and deeper residual stress inside the workpiece.Size change of abrasive particles had little effect on the tangential cutting force.

Probing particle removal in brush scrubber cleaning with fluorescence technique

Brush scrubber cleaning is widely used for post chemical mechanical polishing(CMP)cleaning in semiconductor manufacturing.In this study,an experimental system based on fluorescence technique and particle-tracking velocimetry(PTV)technique was employed to characterize the particle removal displacement and velocity in the interface between a transparent copper film and a porous polyvinyl alcohol(PVA)brush during the cleaning process.Several different cleaning conditions including rotation speeds,loading pressure and cleaning agent were examined and the particle removal rate was compared.Elastic and friction removal,hydrodynamic removal and mixed-type removal are the three types of particle removal.Particles with an arc trace and uniform velocity curves were removed by friction and elastic force which were related to the brush load.Particles with a random trace and fluctuant velocity curves were removed by hydrodynamic force which was determined by the brush rotation speed.The increase of particle removal rate(PRR)with brush rotation speed is a logistic function.It is easier to improve PRR by increasing the brush load or by adding surfactant than by increasing the brush rotation speed.

Particle removal by a single cavitation bubble

In the paper,the behavior of the particle acted by the oscillating bubble is studied using a high-speed video camera.The bubble is generated using a very low voltage of 55 V.Images are captured at a speed of 15000 fps(frames per second).It is found that the velocity of the particle is dependent on the liquid viscosity,particle size,and tube diameter.Particle velocity decreases with the increase of the glycron-water mixture viscosity.A model is presented to predict the velocity and verified by experimental results.These observations may be beneficial for the application in medical treatment.