Criterion of gas and solid dual-phase flow atomization crash in molten metal

A self-invented atomization process, in which molten metal is atomized into powder by a high-velocity gas stream carrying solid particles as the atomization medium, was introduced. The characteristics of powders prepared by common gas atomization and dual-phase flow atomization under similar conditions were compared. The experimental results show that the dual-phase flow-atomized powders have average particle sizes that are one-half that of the common gas-atomized particles;additionally, they possess a finer microstructure and higher cooling rate under the same atomization gas pressure and the same gas flow. The Weber number in the crash criteria of liquid atomization is adopted to measure the crash ability of the atomization media. The Weber number of the dual-phase flow atomization medium is the sum of that of the gas and the solid particles. Furthermore, the critical equation of the crash model in dual-phase flow atomization is established, and the main regularities associated with this process were analyzed.

Three-dimensional Simulation of Gas/Solid Flow in Spout-fluid Beds with Kinetic Theory of Granular Flow

A three-dimensional Eulerian multiphase model, with closure law according to the kinetic theory of granular flow, was used to study the gas/solid flow behaviors in spout-fluid beds. The influences of the coefficient of restitution due to non-ideal particle collisions on the simulated results were tested. It is demonstrated that the simulated result is strongly affected by the coefficient of restitution. Comparison of simulations with experiments in a small spout-fluid bed showed that an appropriate coefficient of restitution of 0.93 was necessary to simulate the flow characteristics in an underdesigned large size of spout-fluid bed coal gasifier with diameter of lm and height of 6m. The internal jet and gas/solid flow patterns at different operating conditions were obtained. The simulations show that an optimal gas/solid flow pattern for coal gasification is found when the spouting gas flow rate is equal to the fluidizing gas flow rate and the total of them is two and a half times the minimum fluidizing gas flow rate. Besides, the radial distributions of particle velocity and gas velocity show similar tendencies; the radial distributions of particle phase pressure due to particle collisions and the particle pseudo-temperature corresponding to the macroscopic kinetic energy of the random particle motion also show similar tendencies. These indicate that both gas drag force and particle collisions dominate the movement of particles.

A new numerical approach of coupled modeling for solid deformation and gas leak flow in multi-coal-seams

From the viewpoint of interaction mechanics for solid and gas, a coupled mathematical model was presented for solid coal/rock deformation and gas leak flow in parallel deformable coal seams. Numerical solutions using the SIP (Strong Implicit Proce- dure) method to the coupled mathematical model for double parallel coal seams were also developed in detail. Numerical simulations for the prediction of the safety range using protection layer mining were performed with experimental data from a mine with potential danger of coal/gas outbursts. Analyses show that the numerical simulation results are consistent with the measured data in situ.

Heat Transfer Method for Solid Flow Rate Measurement in Gas-Solid Two Phase Flow

A new method for measuring the solid flow rate in gas solid two phase flow is introduced in this paper. An electrically heated probe was put in a gas solid two phase flow. For certain solid particles, the flow media with different velocities and concentrations of particles produced different effects on heat transfer with the probe. The solid flow rate can be measured according to the intensity of heat transfer. Experiments were made on a pilot pneumatic conveying device. Research results prove that the method works effectively and reliably.

Mathematical modeling for coupled solid elastic-deformation and gas leak flow in multi-coal-seams

Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformable coal seam can be essentially considered to be compressible with time dependent and mixed permeation and diffusion through a pore cleat deformable heterogeneous and anisotropy medium. Based on this new viewpoint, a coupled mathematical model for coal seam deformation and gas leakage in a double coal seam was formulated and numerical simulations for gas emission from the coal seam are presented. It is found that coupled models might be closer to reality.

CFD studies on the separation performance of a new combined gas–solid separator used in TMSR-SF

In order to comply with discharge standards, a gas–solid separator is used to remove solid particles from the thorium molten salt reactor-solid fuel (TMSR-SF) system. As a key component, it directly determines system energy efficiency. However, current gas–solid separators, based on activated carbon adsorption technology, result in high pressure drops and increased maintenance costs. In the present study, a new combined gas–solid separator was developed for the TMSR-SF. Based on a simplified computational fluid dynamics (CFD) model, the gas–solid twophase flow and the motion trajectory of solid particles were simulated for this new separator using commercial ANSYS 16.0 software. The flow and separation mechanism for this structure were also been discussed in terms of their velocity effects and pressure field distributions, and then the structure was optimized based on the influence of key structural parameters on pressure and separation efficiency. The results showed that the standard k–ε model could be achieved and accurately simulated the new combined separator. In this new combined gas–solid separator, coarse particles are separated in the first stage using rotating centrifugal motion, and then fine particles are filtered in the second stage, giving a separation efficiency of up to 96.11%. The optimum blade inclination angle and numbers were calculated to be 45° and four, respectively. It implicated that the combined separator could be of great significance in a wide variety of applications.

Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

A coupled intravascular-transvascular-interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille＇s law and Darcy＇s law, respectively, transvascular flow is described by Starling＇s law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

A study on periodic boundary condition in direct numerical simulation for gas–solid flow

Direct numerical simulation(DNS) of gas–solid flow at high resolution has been carried out by coupling the lattice Boltzmann method(LBM) for gas flow and the discrete element method(DEM) for solid particles. However,the body force periodic boundary condition(FPBC) commonly used to cut down the huge computational cost of such simulation has faced accuracy concerns. In this study, a novel two-region periodic boundary condition(TPBC) is presented to remedy this problem, with the flow driven in the region with body force and freely evolving in the other region. With simulation cases for simple circulating fluidized bed risers, the validity and advantages of TPBC are demonstrated with more reasonable heterogeneity of the particle distribution as compared to the corresponding case with FPBC.

SOLID-GAS INTERACTION MODELLING FOR MINING SAFETY RANGE AND NUMERICAL SIMULATIONS

Coal and gas outburst is one of the most serious natural calamities in collieries. And protective layer mining is an effective regional method for preventing and controlling coal outburst. However, how to rationally determine the mining safety range in coal mining of protective layer with quantitative analysis is a difficult problem in rock mechanics and mining engineering so far. Then in this paper applied solid gas interaction mechanics for gas leakage flow, the solid gas interaction analysis for the safety range of up protective layer mining has been achieved with the results of experimental research and in situ measurements so that the result of numerical simulation for the difficult problem is closer to reality. Furthermore, the safety range of up protective layer mining can be determined with time dependent based on the result of numerical simulation.

Study on Preparation and Electrical Properties of Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) Solid Electrolyte

Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) solid electrolyte with nonstoichiometric composition was prepared by high temperature solid-state reaction. Phase composition, surface and fracture morphologies of the specimen were characterized by using XRD and SEM, respectively. Ionic conduction was researched by gas concentration cell, the performance of hydrogen-air fuel cell was measured in the temperature range of 600～1000 ℃, and compared them with those of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). The results indicate that Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) is a single-phase perovskite-type orthorhombic system. It is a pure proton conductor in the temperature range of 600～1000 ℃ in hydrogen atmosphere, and its proton conduction is superior to that of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). It is a mixed conductor of oxide ion and electron hole in oxygen atmosphere. At 1000 ℃, the performance of the fuel cell in which Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) as electrolyte is higher than that of BaCe_(0.8)Eu_(0.2)O_(3-α) or Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α).

Numerical simulation on gas-solid flow during circulating fluidized roasting of bauxite by a computational particle fluid dynamics method

A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.

Characteristics of a Flow Transducer Based on Polarized Charge

In this paper we analyze the characteristics of a flow transducer based on polarized charge. The effects of the charged particles in pneumatic pipeline on the measurement pipe potential are discussed in detail and the equivalent circuits of the potential measurement are presented. On this bases, the relationships between mass flowrate and the electrical potential are obtained for different time constants of the measurement circuit. A satisfactory model is presented based on the characteristics of gas solid two phase flow. The linearity of the model is verified by the experiment results. The transducer, which is coaxially connected with the transport pipeline, does not disturb the flow state and has the features of ruggedness and durability, it is especially suitable for industry process control.

固相萃取-气相色谱-质谱法同时测定水中9种药品及个人护理用品

采用固相萃取-气相色谱-质谱联用技术，建立了水体中9种药品及个人护理用品（水杨酸、萘普生、布洛芬、对乙酰氨基酚、降固醇酸、三氯生、双氯酚酸、酮洛芬和双酚 A）的定量分析方法。水样品经稀盐酸调节至 pH =3后，采用 Oasis HLB 固相萃取小柱进行富集净化；选用三甲基氢氧化硫（ TMSH）为衍生化试剂，在常温条件下对目标物进行快速甲基化；以气相色谱-质谱法选择离子监测模式（GC-MS-SIM）进行检测，由2，4，5-涕丙酸为内标进行定量分析。本实验分别对固相萃取和衍生化等前处理条件进行了系统的研究。在优化的实验条件下，方法的回收率为50.7～115.4％，相对标准偏差均不高于10％，检出限为0.03～0.30μg / L，定量限为0．15～1．50μg / L。利用该方法对东莞市某农田灌溉水进行了分析，4种目标物在样品中有检出，最大质量浓度范围为0.176～0.998μg / L。结果表明该方法操作简便，灵敏可靠。

气相色谱-负化学源质谱联用法测定水产品及食用油中氟乐灵的残留量

建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取，4℃冷藏后，采用分散型固相萃取法净化，由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证，同位素内标法定量。在1～40μg / L 范围内氟乐灵农药的线性关系良好；方法定量限（LOQ）为0.02μg / kg；对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验，平均回收率均处于80％～100％之间，RSD≤10.3％；无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。

福建姜黄挥发油化学成分的HS-SPME-GC-MS分析

采用水蒸气蒸馏法提取福建姜黄挥发油,应用顶空固相微萃取进样结合气相色谱-串联质谱联用技术(HS-SPME-GC-MS)分析姜黄挥发油的化学成分。结果表明:姜黄挥发油含有量为7.2%(mL/g),从姜黄挥发油中共分出62个色谱峰,初步鉴定出了其中的51种化学成分,占总挥发油总量的98.41%。在鉴定的化合物中,主要为单萜类化合物和倍半萜类化合物,其中新发现一种主要成分为β-柏木烯,相对含量占比高达26.58%,这可作为福建姜黄挥发油的特征成分和主要品质指标。本研究结果将为福建姜黄植物药材的品质评价提供科学依据。

Numerical investigation of particle deposition on converging slot-hole film-cooled wall

Numerical research on the dilute particles movement and deposition characteristics in the vicinity of converging slot-hole(console) was carried out, and the effect of hole shape on the particle deposition characteristics was investigated. The EI-Batsh deposition model was used to predict the particle deposition characteristics. The results show that the console hole has an obvious advantage in reducing particle deposition in comparison with cylindrical hole, especially under higher blowing ratio. The coolant jet from console holes can cover the wall well. Furthermore, the rotation direction of vortices near console hole is contrary to that near cylindrical hole. For console holes, particle deposition mainly takes place in the upstream area of the holes.

Study of fluid cell coarsening for CFD-DEM simulations of polydisperse gas–solid flows

Particle polydispersity is ubiquitous in industrial fluidized beds,which possesses a significant impact on hydrodynamics of gas-solid flow.Computational fluid dynamics-discrete element method(CFD-DEM)is promising to adequately simulate gas-solid flows with continuous particle size distribution(PSD)while it still suffers from high computational cost.Corresponding coarsening models are thereby desired.This work extends the coarse-grid model to polydisperse systems.Well-resolved simulations with different PSDs are processed through a filtering procedure to modify the gas-particle drag force in coarse-grid simulations.We reveal that the drag correction of individual particle exhibits a dependence on filtered solid volume fraction and filtered slip velocity for both monodisperse and polydisperse systems.Subsequently,the effect of particle size and surrounding PSD is quantified by the ratio of particle size to Sauter mean diameter.Drag correction models for systems with monodisperse and continuous PSD are developed.A priori analysis demonstrates that the developed models exhibit reliable prediction accuracy.

Experimental study on reactor performance of gas-solids low-velocity fluidized beds

Reactor performance of bubbling fluidized bed(BFB)and turbulent fluidized bed(TFB)was carefully examined and systematically compared using catalytic ozone decomposition as a model reaction,based on a complete mapping of local flow structures and spatial distributions of ozone conversion and solids holdup.TFB clearly has a higher conversion and shows better reactor performance than BFB as a result of the vigorously turbulent flow and the relatively homogeneous gas–solids mixing in TEB.Besides,the intensive interaction between gas and solids in TFB leads to greater gas–solids contact efficiency of TFB over that of BFB.Due to gas bypassing and backmixing caused by bubbling behaviours and two-phase structure,BFB deviates significantly from a plug flow reactor and sometimes from a continuously stirred tank reactor.The flow structures essentially dictate the reactor performance in the low-velocity fluidized beds.

Experiments on particle cluster behaviors in a fast fluidized bed

A three-dimensional(3D) fast fluidized bed with the riser of 3.0 m in height and 0.1 m in inner diameter was established to experimentally study the cluster behaviors of Geldart B particles. Five kinds of quartz sand particles(dp= 0.100, 0.139, 0.177, 0.250 and 0.375 mm and ρp= 2480 kg·m^(-3)) were respectively investigated, with the total mass of the bed material kept as 10 kg. The superficial gas velocity in the riser ranges from 2.486 to 5.594 m·s^(-1) and the solid mass flux alters from 30 to 70 kg·((m^(-2)·s))^(-1). Cluster characteristics and evolutionary processes in the different positions of the riser were captured by the cluster visualization systems and analyzed by the self-developed binary image processing. The results found four typical cluster structures in the riser,i.e., the macro stripe-shaped cluster, saddle-shaped cluster, U-shaped cluster and the micro cluster. The increasing superficial gas velocity and particle sizes result in the increasing average cluster size and the decreasing cluster time fraction, while the solid mass flux in the riser have the reverse influences on the cluster size and time fraction. Additionally, clusters in the upper region of the riser often have the larger size and time fraction than that in the lower region. All these effects of operating conditions on clusters become less obvious when particle size is less than 0.100 mm.

Numerical Investigation of Coupling Effect in Muitipipe Ceramic Filter Vessel

The Reynolds stress transport model and the Eulerian two-fluid model provided by the FLUENT code were applied to evaluate the gas-particle two-phase flow in the ceramic filter vessel. The ceramic filter vessel contains six candle filters, which are arranged in the form of equilateral hexagon. The variation of the areal density of the filter cake during the filtration and the back-pulse process were analyzed. The coupling effect between filters, gas and solid, filtration and pulse cleaning process were investigated, respectively. The numerical results show a good approach to predict the particle distribution in the vessel and the particle deposition on the filter element. This study provides the base for the intensive study on the analysis of the gas-particle flow in the filter vessel.