Agglomeration Of Fine Particles Research Articles

Study on condensation of oily particles under the influence of water vapor phase transition

To address the problem that oily fine particles are too small to be easily captured by traditional dust removal equipment, which hinders improving the purification efficiency, this paper proposes using the technical principle of water vapor phase transition to conduct experiments and simulations. A set of water vapor experimental devices for fine particles of oil mist is designed, and the data are analyzed by a Grimm spectrometer. The experimental results show the phase change of water vapor has a remarkable effect on the agglomeration of oily fine particles. Phase change condensation makes the particle size of fine particles increase by 5–10 times in a truly brief time, and the polymerization and removal efficiency are greatly improved. To analyze the changes of the coalescence characteristics in a larger range of parameter changes, the Euler multiphase flow model is adopted, the particle condensation growth rate function is introduced by a user-defined function to establish a coalescence model and the heterogeneous condensation growth characteristics of oily particles are analyzed in a supersaturated water vapor environment. The simulation results show that the condensing chamber temperature of the condensing chamber is 283 K, and the lower the air flow rate of the condensing chamber, the more favorable the heterogeneous condensation growth of oil particles. The change rule of agglomeration characteristics of oily particles obtained by experiment and simulation proves the feasibility of improving the removal efficiency of oily fine particles.

Particle agglomeration via resonant acoustic mixer for dry powder inhalation

The work presented in this paper employed a resonant acoustic mixing (RAM) process to optimize the fine particle agglomeration process for dry powder inhalation to achieve efficient pulmonary delivery of melatonin. The formulation prepared by acoustic mixing with the double layer grids demonstrated superior agglomerate particle size distribution and approximately 90% of the metered dose in the dosing chamber was emitted from Turbuhaler® (90% emitted dose). Acceleration force during acoustic mixing significantly affected the packing fraction of mixtures and mechanical strength of agglomerates resulting in improved fine particle fraction. The particle agglomeration via RAM can improve the efficiency of agglomerate production by utilizing the internal space of the mixer to induce more particle collision. The agglomerates formulation exhibited ideal fine particle fraction of 47.65 ± 1.46% and 56.02 ± 2.55% at flow rates of 30 and 60 L/min, respectively. The fine particle deposition was only slightly affected at the lower air-flow rate, suggesting a reliable inhalation performance in vivo.

Experimental investigation on the agglomeration performance of pre-charged micro-nano particles in uniform magnetic field

Agglomeration of fine particles is an essential procedure to improve separation efficiency of dust-removal devices. This paper focuses on the treatment of biomass Micro-Nano particles using cascade electrostatic and magnetic fields. A carefully designed wind tunnel is built to investigate the agglomeration performance of pre-charged Micron-Nano particles (0.016–9.84 µm) in uniform magnetic field. The influence of supply voltage (10–30 kV) in the electrostatic unit and the bulk flow velocity (1–5 m/s) across the device upon agglomeration is studied. The results indicated noticeable agglomeration behavior because of reduced submicron particles and increased larger particles. Strengthening Supply voltage input has a positive yet minimum effect on the overall agglomeration efficiency. Effect of bulk flow velocity on agglomeration is remarkable due to magnetic field. Therefore, agglomeration of pre-charged particles in uniform magnetic field is dominated by Lorentz effect and stream-wise spacing of the device. This work provides a reference for further computational attempt in the future.

Rapid discovery of agents for improved chemical agglomeration of fine particles in coal-fired flue gas – A molecular dynamics simulation-based approach and its validation

The agglomeration of fine particles, particularly PM2.5, into larger particles, has been a pivotal focus in the battle against atmospheric haze, garnering significant attention in regions addressing this challenge. In this study, a molecular dynamics (MD) simulations-based approach was proposed for the rapid screening of chemical agents and optimal operating conditions for the improved agglomeration of particulate matter in coal-fired power plants. Our findings reveal a distinct hierarchy in agglomeration effectiveness of chemical agents, with the following order: glucose/mannose > carboxylic acid (-COOH-) > nitrate (-ONO2) > hydroxyl (-OH) > ester (-COOC-) > aldehyde (-CHO). Additionally, an exploration delves into fifteen water-soluble polymers, including soluble starch, carboxyl methylcellulose, etc. Remarkably, soluble starch emerges as the most promising agent for the agglomeration of fine particles. Through analyses of interaction energy and the Radial Distribution Function, it is evident that neutral conditions and a temperature at 378 K offer the most conducive environment for chemical agglomeration. Empirical experiments confirmed the outstanding performance of soluble starch in the agglomeration of fine particulate matter, resulting in the excellent fine particles agglomeration performance.

Effect of Wettability, Number of Liquid Phases, and Agitation Procedure on Agglomeration/Breakup/Transfer of Fine Particles in Liquid

To discuss nonmetallic inclusion behaviors in a secondary refining process, cold model experiments on agglomeration, breakup, and transfer of fine particles are performed varying the operating factors such as an energy input rate, wettability, agitation practice, and the number of liquid phases. When the other operating conditions are the same, the agglomeration rate of the 1‐particle (isolated particle) with a hydrophobic property is larger than that with a hydrophilic one, and the transfer rate of the 2‐particle (cluster of 2 isolated particles) has the same tendency. The number of the 1‐particle with the hydrophobicity is estimated to increase at the transfer site of the particles from an open eye to a heavy liquid due to a bubble breakup, whereas the 1‐particle with the hydrophilicity shows an opposite trend because of less adhesion on the bubbles. The 1‐particle in the dual phase transfers from the open‐eye spot to a light liquid, although the value is not so much as that of the decrease in the agglomeration. A transfer condition of the inclusion composed of Al2O3 or CaO⋅Al2O3 is calculated when a particle contacts with a solid/liquid interface, and the CaO⋅Al2O3 inclusion is estimated to be engulfed above 3.34 μm in diameter.

Research Progress on the Impact of Acoustic Waves on the Agglomeration of Oily Fine Particles in Industrial Oil Mist Environment

Currently, undetectable damage to workers and factory products is caused by the large number of oily fine particles present in the industrial environment. Previous studies have shown that different intensities of sound waves can promote the coalescence of fine particles, and the combination of water vapor condensation can further enhance the effect of acoustic coalescence. However, the research on acoustic coalescence is not extensive enough at present, especially research on the mechanism of the coalescence and growth of oily fine particles under acoustic and water vapor complex fields, which is even less studied. This paper focused on summarizing domestic and foreign research results on the interaction mechanism of acoustic convergence on particles and the agglomeration and growth of particles under the action of acoustic convergence and combined water vapor condensation, so as to explore the technical path of using acoustic convergence and combined water vapor condensation to regulate the size of oily fine particles and improve the purification efficiency in industrial situations. This research has significant scientific significance and application value for industrial environmental control, pollutant emission control, and healthy environment construction.

Evaluation of Ca-Based Sorbents for Gaseous HCl Emissions Adsorption

The problem of acid gas exhaust emissions treatment has not been fully resolved at present. Dry adsorption of acid gases with alkaline sorbents is currently being investigated, to improve solid sorbents. In this study, 5 types of hydrated lime were characterised and tested. The sorption capacities were measured by means of a system consisting of a feed line (HCl/N2), a thermostatic reactor and a water absorber. The physical characteristics of sorbent samples were also compared. Analyses conducted with scanning electronic microscopy revealed that sample C1 showed uniform particle distribution. Samples C2 and C3 showed the co-presence of fine and coarse particles. Sample C4 showed very fine particles with agglomeration phenomena. In sample C5, fibrous elements were found. Energy dispersive spectrometry (EDS) analyses showed a similar composition of the samples, with the exception of the presence of Mg in some of them. After 30 min of testing, the following differences in sorption capacities with respect to C1 (3.59 mg g−1) were found: C2, −20%; C3, −13%; C4, −17%; C5, −3%. Higher sorption capacities were associated with more uniform particle size distributions. Conversely, agglomeration of fine particles may have adversely affected the performance of sorbents.

Experimental Study on the Agglomeration of Oily Fine Particles by Sound Wave

Oily fine particles are an important air pollutant in industrial environments. Workers exposed to oil mist for a long time face great health risks. Particle growth pretreatment is a technical principle to increase particle size and improve purification efficiency. Acoustic waves are commonly used to acheive particle growth, and a large number of acoustic wave agglomeration experiments have been carried out on non-oil fog. However, studies on oily particles are few. On the basis of previous studies on acoustic agglomeration of non-oily particles, this experiment designed a set of experimental equipment to compare the agglomeration effect of oily and non-oily particles. It was found that the agglomeration effect ratio of oily and non-oily particles to φ1oiliness/φ1non-oily particles was greater than 1. Therefore, the agglomeration effect of oily particles under stationary acoustic waves was more obvious. Results clearly show that oily particles have a higher agglomeration ability. In this study, a traditional ventilation and purification technology was expanded to include sound agglomeration technology into the pretreatment stage of purification and dust removal, thereby demonstrating feasibility of improved purification efficiency of an oily fine particle purification system, and laying a foundation for engineering applications.

Research in the area of obtaining of activated alumina. Part 5. Various technological approaches to the process of fine grinding of high-alumina raw materials

The results of studying the process of fine grinding of α-Al2O3 in the presence of polyethylene glycol (PEG) and an antistatic composition are presented. It is shown that the main reason for the agglomeration of fine particles is the effect of the appearance of an electrostatic surface charge. The introduction of PEG prevents the appearance of a «pseudo-viscous grinding medium», removing the excess electrostatic charge on the surface of newly formed ultrafine particles, and also intensifies the process of abrasion of primary alpha-alumina crystals. The antistatic composition successfully neutralizes the surface electrical charge, but does not have the effect of a grinding aid.

Agglomeration of fine hydrophobic particles: 1D and 2D characterization by dynamic image analysis of in-line probe data

The agglomeration dynamics of small poorly wetted alumina particles with a wetting angle of 134° was investigated in a baffled stirred tank by dynamic image analysis with an in-line camera probe. Dynamic image analysis of the in-line probe data allows for a multidimensional characterization of particle properties during the agglomeration process, that was evaluated with respect to the particle size, aspect ratio, and solidity of the primary particles and the agglomerates generated. Agglomeration of the particles in 0.75 mol/l sodium chloride solution leads to the formation of a bimodal particle size distribution, where the first mode represents non-agglomerated primary particles and the second mode represents the agglomerates with an equilibrium size that is smaller than the corresponding Kolmogorov microscale. The bimodal size distribution can be approximated by mixture models based on 1D size or 2D size-aspect ratio data, from which the fractions of agglomerates and primary particles can be determined.

Spraying coupled with turbulence mechanisms enhanced the removal of fine particles in wet flue gas

Agglomeration pretreatment has been proved as the most effective method to enhance the removal of fine particulate matters (PM2.5). However, the common technologies were not suitable for the high-humidity conditions, such as the wet flue gas after desulphurization. Herein, we proposed a method for enhancing the agglomeration of fine particles by applying the combination mechanisms of spraying and turbulence effects. Through the experiments and simulation studies, we found that the number concentration proportions of fine particles can decrease by 19.9% in the size range of 0–0.5 μm, and increased by 15.2% in the range of 0.5–3.0 μm with the spray volume of 15 L/min. The turbulence effects can make the movement states of fine particles more disordered, and increase the collision and agglomeration opportunities among particles and droplets. The average particle size can be increased by 35% with the integrated turbulence structures and spraying. Combined with the agglomeration system, the graded removal efficiency of fine particles with the size of below 1.0 μm in WESP can be improved by 15%. This study contributes to comprehend the mechanism of turbulence on the particle agglomeration, and provides a reference for the upgradation and transformation of the existing dust removal equipment.

Study on surface physical and chemical mechanism of nanobubble enhanced flotation of fine graphite

It has been concluded in a recently published investigation that the nanobubble flotation process significantly reduces the number of fine flake graphite flotation stages and improves the flotation performance. The present study was conducted to explore the mechanisms of surface nanobubbles enhancing flake graphite flotation by investigating effects of nanobubbles on surface properties of graphite and interactions between particles and bubbles by use of contact angle analyzer, zeta potential analyzer, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The study results show that nanobubbles can improve the surface properties of graphite and enhance the adsorption effect of collector, which increased the contact angle of the graphite surface by 11.93° compared with conventional flotation. Infrared spectroscopy and potential analysis showed that the nanobubbles could enhance the hydrophobic attraction and reduce the electrostatic repulsion between the collector and the graphite surface, which was beneficial to enhance the hydrophobic surface of the graphite and enhance the agglomeration of fine graphite particles. XPS analysis showed that the nanobubbles covered polar hydrophilic groups (such as CO, CO, COOH) on the graphite surface, which enhanced the adsorption of collector to improve the hydrophobicity of graphite surface.

Physicochemical Characterization of Air Pollution Particulate Matter (PM2.5 and PM>2.5) in an Urban Area of Cotonou, Benin

PM2.5 and PM>2.5 samples were collected in Cotonou (Benin) using high volume cascade impaction air samplers. The samplings were based on continuous collection over twelve days. Physical and chemical characteristics of samples were determined by size distribution (laser granulometry), specific surface areas (BET method), inorganic elements (ICP-MS), water-soluble ions (IC), CHNS analysis and organic compounds (GC-MS). Average concentrations of air particulate matter were 180.9 µg/m3 and 94.5 µg/m3 in PM2.5 and PM>2.5, respectively. The higher water-soluble ions recorded were Ca2+,SO42−,NO3−, Na+ and Cl− for both PM. Moreover, concentrations were almost two-fold higher for PM2.5 compared to PM>2.5, with 10.7 µg/m3 of total metals found in PM2.5 versus 5.6 µg/m3 in PM>2.5. Both PM samples under study presented similar repartition of elements considering their percentages. Results suggested that PM>2.5 samples contain agglomerates of fine particles. Identification tools of major pollution source as inorganic elements, paraffins, fatty acids ratios and PAHs ratios indicated that PM under study originated from traffic exhaust.

Acoustic agglomeration characteristics of fine solid particles under effect of additional droplets

Agglomeration of fine solid particles under the excitation of external acoustic field has potential applications in the field of ultra-low emission of combustion pollutants. It is expected that the performance of particle agglomeration can be improved by adding large sized liquid droplets. According to the dynamic process of acoustic agglomeration, including the particle motion, collision, agglomeration and rebound, a model of acoustic agglomeration for gas-liquid-solid three phase system with coexistence of liquid droplets and solid particles in gas phase is developed by using the direct simulation Monte Carlo (DSMC) method. Using this model, numerical simulations are performed to investigate the process and performance of acoustic agglomeration of fine solid particles under the effect of additional droplets. The numerical results are compared with experimental data, and the proposed model is validated. On this basis, the dynamic behaviors of acoustic agglomeration of fine particles in the case with additional droplets are explored. Furthermore, the influences of the diameter and number concentration of additional droplets on the performance of acoustic agglomeration of fine particles are examined. The results show that rapid agglomeration among the solid fine particles and additional droplets can be achieved by adding droplets into the acoustic field, yielding large sized liquid-solid mixed-phase particles. In this process, the agglomeration efficiency of fine particles increases significantly. It is also found that the diameter and number concentration of additional droplets are important factors that affect the acoustic agglomeration of fine particles. The agglomeration efficiency of fine particles rises, while the magnitude of increase tends to decrease with the droplet diameter and number concentration increasing. The research results can provide both theoretical basis for modeling the agglomeration process of complex particle systems and method guidance for achieving the ultra-low emission of fine particles from combustion sources.

Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C4H4N4 system, respectively. The phase structure, functional groups and synthesis mechanism were analyzed by XRD and FT-IR, and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were discussed. The results show that C3H6N6 has a stable triazine ring structure, and its chemical bond is firm and difficult to break, so AlN cannot be synthesized directly by solid-solid reaction at room temperature. However, there are a large number of nitrile groups (-CN) and amino groups (-NH2) in C4H4N4 molecules. Under the combined action of plasma bombardment and mechanical energy activation, C4H4N4 molecules undergo polycondensation and deamination, so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=, ≡N, etc. These groups and ball milling activated Al can synthesize nano-AlN at room temperature, with a conversion rate of 92%. SEM, DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 nm. The surface morphology of the powder was loose and porous, and it had strong activity. After annealing at 800°C, the conversion rate of the Al+C4H4N4 system reached 99%.

Effects of Sintering Temperature and Yttria Content on Microstructure, Phase Balance, Fracture Surface Morphology, and Strength of Yttria-Stabilized Zirconia

Currently, ceramics are widely used in various industry branches, especially in energy, chemistry, and aerospace, as well as in medicine. Yttria-stabilized zirconia (YSZ) having unique electrical, thermal, and mechanical properties is one of the most popular ceramics for such applications. In this study, the influence of sintering temperature and yttria percentage on the microstructure and mechanical behavior of YSZ ceramics have been investigated. Corresponding mixtures of ZrO2 powder doped with 3 and 6 mol% Y2O3 powders (hereinafter: 3YSZ and 6YSZ) were prepared, and a series of ceramic specimens were sintered in argon at 1450 °C, 1500 °C, and 1550 °C for 2 h. Changes in the morphology and size of microstructural components as well as their distribution were analyzed with respect to the sintering mode, phase composition, flexural strength, and fracture surface morphology. The 3YSZ and 6YSZ ceramics sintered for 2 h at 1550 °C and 1450 °C, respectively, exhibited the highest levels of strength due to the presence of agglomerates of fine tetragonal zirconia phase particles with high bond strength, as well as larger grains of the monoclinic zirconia phase. The dominant fracture micromechanisms in both the 3YSZ and 6YSZ ceramics related to their high strength are discussed.

Promoting fine particle agglomeration through organic agglomeration solutions with charged atomization

• The charged atomization technology of organic agglomeration solution was proposed and investigated. • Main influence factors and agglomeration mechanism were fully investigated. • The atomization and agglomeration performance of agglomeration solution before and after charged atomization were compared. • Charged atomization improved the agglomeration ability of organic agglomeration solution greatly. Chemical agglomeration is an effective method for agglomerating fine particles. Generally, an aqueous solution of an organic polymer is used as the agglomeration solution. However, these water-soluble polymers have high viscosity, resulting in a poor atomization effect of the solution, which significantly reduces the probability of collision between the agglomeration solution droplets and particles and further reduces the agglomeration efficiency of particles. To improve the agglomeration efficiency, the charged atomization technology of organic agglomeration solutions was proposed and investigated. The results showed that although the agglomeration effects of different organic agglomeration solutions on particles were different, the agglomeration performance improved after charged atomization. Among the four solutions obtained using the charged atomization technique, sodium carboxymethyl cellulose (CMC) and sodium alginate (SAA) showed the largest improvement in performance. Compared to the uncharged droplet, the agglomeration efficiency of fine particles increased by 53.4% for the 0.01% CMC solution under the charged droplet condition. With an increase in the mass concentration, the agglomeration efficiency of the particles increased but the change rate decreased, and this trend was more apparent after charged atomization. As the concentration increased from 0.03% to 0.1%, the change rates of the relative agglomeration efficiency of CMC before and after charged atomization were 11.2% and 2.4%, respectively. The change in droplet size is among the main reasons for the change in the agglomeration ability of an organic solution. Since the conductivity and viscosity of the solution affect the change in droplet size after charged atomization, it also has an effect on the agglomeration efficiency of the solution. The agglomeration performance of the organic agglomeration solution with high conductivity and low viscosity improved significantly after charged atomization. The particles exhibited characteristics of more compact chains and clusters after charged atomization.

Induced adsorption and agglomeration under bipolar corona discharge to enhance the simultaneous removal of trace mercury and fine particles

• The induced adsorption of Hg 0 was enhanced by the bipolar corona discharge through sorbent. • The addition of MnO x sorbent promoted the agglomeration of fine particles in electric field. • The corona discharge had a guidance effect on the migration of mercury-carried particles. Fine particulate matter (PM 2.5 ) and gaseous mercury emitted from industrial flue gas are highly toxic to humans and the environment. Promoting the enrichment of non-condensable gaseous elemental mercury (Hg 0 ) and enhancing the nucleation growth of fine particles can cause them to be simultaneously removed in dust removal devices. However, the sorbent itself is also a fine particle, and the fate of the mercury-carried sorbent is unclear. Herein, we propose a novel method that uses manganese oxides (MnO x ) for the induced adsorption of Hg 0 to coagulate the sorbent and fine particles, assisted by bipolar corona discharge. The results showed that Hg 0 removal efficiencies increased from 10.2% to 32.2% with sorbent injection when the corona discharge was +21 kV and −24 kV. Simultaneously, the fine particle removal efficiencies increased from 23.6% to 46.3%. The distribution results confirmed that mercury was enriched on the particles through sorbent and fine particle agglomeration, and the mercury-carried particle proportion was concentrated in the size range of 0.5–2.5 μm. The induced adsorption performances were enhanced under bipolar corona discharge through the MnO x sorbent. In addition, the agglomeration of fine particles was enhanced as the average particle size increased by 43% when the MnO x sorbent was injected into the simulated gas. This study provides valuable guidance for clarifying the relationships between the fine particles and carried substances, and it contributes to achieving the synergistic removal of multiple contaminants.

Charged movement characteristics and enhanced removal of fine particles under the electric fields coupling with turbulence from industrial flue gas

• The cross electrode can form an electric field with the larger impact area and higher electric field intensity. • The coupling effect of cross corona discharge and turbulence can prolong the particle residence time in the electric field. • The longer deviate distance from electrode can provide more opportunities for fine particles to collide and coagulate. Fine particulate matters emitted from the industrial flue gas are the primary reason for the serious haze problem. The agglomeration has been proven an effective method to improve fine particle removal efficiency, but the movement characteristics in the process and their effects on the agglomeration are unclear. In this study, the agglomeration and the underlying mechanisms in the various electric fields were investigated. The results showed that the removal efficiency of fine particles can reach near 80% under the coupling effect of turbulence and cross discharge electrode, and the particle size can be increased by 30% simultaneously. The electric field intensity with cross electrode approached 650,000 V/m and higher than another three conventional electrodes with 60,000–200,000 V/m. The residence time of fine particle was extended to 0.2 s in the electric field with cross electrodes, and the deviate distance from the discharge electrode was nearly 3 times than other electrodes. The longer residence time and the more disordered movements can make fine particles carry more charge amounts and have more opportunities to finish coagulations. This study discussed the charged particles movement characteristics under the electric fields coupling with turbulence, and explored the further effects on the agglomeration and removal of fine particles. It’s designed to provide the guidance for the setting and improvement of electric fields in the dust removal equipment.

Investigation on fine particle agglomeration and separation promoted by different bluff bodies

Using particle agglomeration to help separate fine particles receives increasing attention in air purification processes. Recent studies suggested that enhanced turbulence using bluff bodies can significantly improve the agglomeration of fine particles. However, since micron-sized particles are difficult to measure, the current exploration of flow fields and particles is mainly based on simulations and lacks experimental validation. This paper innovatively used a phase doppler particle analyzer to measure the flow field in terms of velocity, streamline and turbulence intensity, as well as particle size and number concentration in an agglomeration chamber with a bluff body located at the center. Different shaped bluff bodies were also considered. It was found that low-velocity recirculation region with different shapes appeared in the wake, and vortex flow with special structures were observed. From the perspective of particles, the development of the flow field generated by a single bluff body effectively caused an increase in particle size and a decrease in particle number, which is because that the flow field promotes collisional agglomeration. More specifically, for V-structure bluff body, the particle size improved from 6 μm to a maximum of 13 μm and the particle number concentration decreased by 8 times. The agglomeration efficiency for PM2.5 and PM10 reached 89.06% and 87.38% respectively. Furthermore, by analyzing the velocity of different sized particles, it was reasonable to assume that different sized particles appeared to have velocity differences due to recirculating vortex flow, while the overlapping trajectories of positive and negative moving particles was mainly responsible for the collision probability enhancement. This paper presents new insights into particle agglomeration separation for this environment-friendly and low-cost technology.