Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.

Evaluation and Influencing Factors on Particle Agglomeration in RAP

Asphalt extraction test and scanning electron microscopy(SEM) were used for analysis of agglomerations of reclaimed asphalt pavement(RAP) particles. In order to quantify the agglomeration degree of RAP, the fineness modulus ratio(FMR) and the percentage loss index(PLI) were proposed. In addition, grey correlation analysis was conducted to discuss the relationship between particle agglomerations and RAP size,asphalt content(AC), and surface area. Two indexes indicate that the agglomeration degree increases in general as the RAP size reduces. This can be attributed to that particles are prone to agglomeration in the case of higher AC. Based on the SEM images and the material composition of RAP, the particle agglomeration in RAP can be classified into weak agglomeration and strong agglomeration. Grey correlation analysis shows that AC is the crucial factor affecting the agglomeration degree and RAP variability. In order to produce consistent and stable reclaimed mixtures, disposal measures of RAP are suggested to lower the AC of RAP.

Particle Size Distribution,Powder Agglomerates and Their Effects on Sinterability of Ultrafine Alumina Powders

An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.

Particle Agglomeration in Bipolar Barb Agglomerator Under AC Electric Field

The development of an efficient technology for removing fine particles in flue gas is essential as the haze is becoming more and more serious.To improve agglomeration effectiveness of fine particles,a dual zone electric agglomeration device consisting of a charging chamber and an agglomeration chamber with bipolar barb electrodes was developed.The bipolar barb electric agglomerator with a polar distance of 200 mm demonstrates good agglomeration effectiveness for particles with a size less than 8.0μm under applied AC electric field.An optimal condition for achieving better agglomeration effectiveness was found to be as follows：flue gas flow velocity of3.00 m/s,particle concentration of 2.00 g/m^3,output voltage of 35 kV and length of the barb of16 ram.In addition,4.0-6.0μm particles haste the best effectiveness with the variation of particle volume occupancy of-3.2.

Transient flameout process of boron-magnesium agglomerates during combustion in oxygen-rich atmospheres

In this study,boron–magnesium agglomerates with varying mass ratios were prepared by drying a micron-sized boron–magnesium mixed suspension,and the combustion process of these agglomerates under different oxygen-rich concentrations were investigated using a laser ignition system.The test results showed that when the mass fraction of magnesium powder in boron-magnesium agglomerates exceeded a certain threshold(between 2%and 5%),flame extinction and reignition occurred after a significant reduction in the agglomerate volume during combustion.This process is referred to as the transient flameout process,which is affected by the magnesium content of the agglomerate and the oxygen concentration in the ambient atmosphere.An increase in the magnesium content or oxygen concentration makes this phenomenon more pronounced.During weakening of the flame intensity,a dark film gradually covered the particle surfaces.X-ray diffraction and elemental analyses of the cross-section and outer surface of the condensed combustion product suggested that the dark film is primarily composed of Mg-B-O ternary oxides.This film prevents direct contact between boron and oxygen,thereby inhibiting surface and gas-phase reactions and leading to the occurrence of the transient flameout phenomenon.

Bipolar charged aerosol agglomeration and collection by a two-zone agglomerator

In older to collect fine particles more efficiently, a new-type electrostatic agglomerator with two zones was developed. The distinguishing feature of this electrostatic agglomerator is that the particles are bipolarly charged and coagulated in the same alternating electric field simultaneously. The silica flour with 2 fun mass median diameter and the smoke from burning wood powder were used as test aerosol. The comparison experimental results have shown that when the mean electric field is 4 kV/cm the collection efficiency of the new electrostatic agglomerator was 98.2% for silica flour and 67.4% for wood powder smoke, Under the same experimental condition. the collection efficiency of the electrostatic agglomerator with three zones was 97.4% for collecting silica flour and the collection efficiency of the electrostatic precipitator was 56.3% for wood powder smoke.

Preparation,Microstructure and Properties of NiO-Cr_2O_3-TiO_2 Infrared Radiation Coating

The spherical agglomerated particles were fabricated by spray drying with the powders of NiO, Cr2O3 and TiO2. Plasma spray power, which has good property of flowability, was acquired by heat treatment from the particles at 1200℃ in the reducing atmosphere. Dark and uniform coating of More than 50 μm thick was deposited on the copper sheet substrate by plasma spraying. It is found that the infrared normal total emissivity of the coating is up to 0.91 at 600℃ by infrared radiation testing. The X-ray diffraction analysis shows that the formation of （Cr0.88Ti0.12）2O3 and spinel structural NiCr2O4 in the coating is the main reason for high efficient infrared radiation, and the phase structure and performance of coating is favorable under the thermal cycle between room temperature and 600℃.

Particle agglomeration behavior in fluidized bed during direct reduction of iron oxide by CO/H_(2)mixtures

The agglomeration behavior of particles significantly impacts on the defluidization occurring in a fluidized bed during the direct reduction process.The influence of CO/H_(2)ratio on surface diffusion of iron atoms was proposed,and the solid bridge force between iron oxide particles was quantificationally analyzed.Moreover,the solid bridge force was successfully added into a CFD–DEM(computational fluid dynamics–discrete element method)model combined with heat transfer and mass transport to investigate the detailed information of agglomeration in a fluidized bed,including the spatial distribution of temperature,velocity and metallization of iron oxide particles.The region of defluidization is sensitive to the reduction temperature.At the same reduction temperature,the iron oxide powder will perform higher metallization and stable fluidization properties with molar fraction of H_(2)in the range of 0.6–0.8,when iron oxide is reduced by CO/H_(2)mixture.

Removal of inhalable particles from coal and refuse combustion by agglomeration with solid nuclei

Airborne inhalable particles are a potent environmental pollutant. Formed via industrial processes, separation of these particles is difficult using conventional clean up techniques. In this work, solid nuclei particles of different chemical compositions were introduced into an agglomeration chamber with simulated flue gases to investigate their ability to remove these particles. Organic nuclei were able to capture more inhalable particles from coal-derived fly ash than inorganic nuclei, though these proved more effective for the agglomeration of inhalable particles in refuse-derived fly ash. Increasing the diameter of the solid nuclei benefitted the agglomeration process for both types of ash. Varying the local humidity changed adhesion between the particles and encouraged them to aggregate. Increasing the relative humidity consistently increased particle agglomeration for the refuse-derived ash. For coal-derived fly ash, the removal efficiency increased initially with relative humidity but then further increases in humidity had no impact on the relatively high efficiencies. After agglomeration in an atmosphere of 62% relative humidity, the mean mass diameter of inhalable particles in the coal-derived fly ash increased from 3.3 to 9.2 μm. For refuse-derived fly ash, agglomeration caused the percentage of particles that were less than 2μm to decrease from 40% to 15%. After treatment at a relative humidity of 61%, the mean size of inhalable particles exceeded 10 μm.

Suppression of voltage decay through adjusting tap density of lithium-rich layered oxides for lithium ion battery

The voltage decay of lithium-rich layered oxides(LLOs)is still one of the key challenges for their application in commercial battery although these materials possess the advantages of high specific capacity and low cost.In this work,the relationship between voltage decay and tap density of LLOs has been focused.The voltage decay can be significantly suppressed with the increasing tap density as well as the homogenization of the primary or secondary particle size of agglomerated spherical LLOs.Experimental results have shown that an extreme small voltage decay of 0.98 m V cycle^(-1)can be obtained through adjusting the tap density of agglomerated spherical LLOs to 1.99 g cm^(-3),in which the size of primary and secondary particles are uniform.Our work offers a new insight towards the voltage decay and capacity fading of LLOs through precursor preparation process,promoting their application in the real battery in the future.

Fluidization of nano and sub-micron powders using mechanical vibration

The fluidization behavior of nano and sub-micron powders belonging to group C of Geldart＇s classification was studied in a mechanically vibrated fluidized bed （vibro-fluidized bed） at room temperature. Pretreated air was used as the fluidizing gas whereas SiO2. Al2O3, TiO2, ZrSi, BaSO4 were solid particles. Mechanical vibration amplitudes were 0.1, 0.25, 0.35, 0.45mm, while the frequencies were 5, 20, 30, 40 Hz to investigate the effects of frequency and amplitude of mechanical vibration on minimum fluidization velocity, bed pressure drop, bed expansion, and the agglomerate size and size distribution, A novel technique was employed to determine the apparent minimum fluidization velocity from pressure drop signals. Richardson-Zaki equation was employed as nano-particles showed fluid like behavior when fluidized. The average size of agglomerates formed on top of the bed was smaller than those at the bottom, Size distribution of agglomerates on top was also more uniform compared to those near the distributor. Larger agglomerates at the bottom of the bed formed a small fraction of the bed particles. Average size of submicron agglomerates decreased with increasing the frequency of vibration, however nano particles were less sensitive to change in vibration frequency. Mechanical vibration enhanced the quality of fluidization by reducing channeling and rat-holing phenomena caused by interparticle cohesive forces.