Influence of Blade Outlet Angles on Separation Performance of Guide Vane Type Axial Flow Cyclone Tube

The influences of the internal and external outlet angles on separation performance and flow field are compared and analyzed. Two arc functions are employed for controlling the internal and external angles. The separation process in the cyclone tube is calculated by using two-fluid model based on the Eulerian-Eulerian method.The results show that the structure with the internal outlet angle smaller than the external one is more beneficial to the separation performance. It is found that the small internal angle can help increase the swirl number,while the small external angle can help increase the friction coefficient. Several groups of numerical simulations are conducted for the air intake unit of the gas turbine in practice. When the internal outlet angle is 35° and the external outlet angle is 40°,the blade has sufficient cyclone strength and the separation rate of particles with diameters of 10—100 μm is between70%—98%. The small blade angle is more conducive to the separation of fine particles,leading to violent collision of large particles on the outer wall and reduction of separation efficiency. In addition,reducing the external angle is conducive to the discharge of large particles.

Separation performance of graphene oxide as stationary phase for capillary gas chromatography

Graphene oxide（GO） has attracted extensive attention due to its unique properties and potential applications.Here,we report the investigation of GO nanosheets as a stationary phase for capillary gas chromatographic（GC） separations.The GO column,fabricated by a new one-step coating approach,showed average McReynolds constants of 308,suggesting the medium polar nature of the GC stationary phase.The GO stationary phase achieves good separation for analytes of different types with good peak shapes,especially for H-bonding analytes,such as alcohols and amines.The different retention behaviors of GO stationary phase from the conventional stationary phase may originate from its multiple interactions with analytes,involving H-bonding,dipole-dipole,π-π stacking and dispersive interactions.Moreover,GO column showed good separation reproducibility with relative standard deviation（RSD%） less than 0.24%（n = 5） on retention times of analytes.

Separation performance of polydopamine-based cucurbit[7]uril stationary phase for capillary gas chromatography

Polydopamine（PDA） coating, a nature-inspired polymer, has attracted great attention in many areas due to its high adhesion strength and stability on almost all types of substrate surfaces. This work presents the first example of using PDA coating as a column pretreatment method in capillary gas chromatography（GC） and its employment in the column fabrication of cucurbit[7]uril（CB7） stationary phase. The fabricated PDA-CB7 column exhibited weakly polar nature and had advantages over CB7 column without PDA for the separations of some critical analytes in GC. This work demonstrates the advantage and potential of using PDA as a facile column pretreatment method in capillary GC column fabrication.

High Performance Hydrophobic Interaction Chromatography-A New Approach to Separate Intermediates of Protein Folding──Ⅰ.Separation of Intermediates of Urea-unfolded α-Amylase

Based on the different hydrophobicities of the intermediates of proteins the various conformational intermediates of the refolding of a-amylase originally denatured with 8.0 mol/L urea solution were separated with high performance hydrophobic interaction chromatography(HPHIC). Compared to the separation of the same intermediates with weak anion exchange chromatography and size-exclusion chromatography the result obtained with HPHIC is the best It would be expected that HPHIC may be a strongly potential tool to separate intermediates of some proteins which cannot be, or cannot completely be refolded by HPHIC.

Highly Soluble Polyimides Containing Di-tert-butylbenzene and Dimethyl Groups with Good Gas Separation Properties and Optical Transparency

A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials.A series of novel polyimides(PI 3a-3c)with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides(3,3',4,4'-biphenyltetracarboxylic dianhydride,4,4'-oxydiphthalic anhydride,and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride)by one-step high temperature polycondensation.The prepared polyimides exhibited high solubility and good membrane forming ability:they could be dissolved not only in some high boiling solvents such as DMF,NMP,DMAc,and m-Cresol at room temperature,but also in some low boiling solvents such as CHCl3,CH2Cl2,and THF.Their solubility in most solvents could exceed 10 wt%,and the flexible membranes could be obtained by casting their solutions.The prepared membranes exhibited good gas separation properties.The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer,respectively,and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3,respectively.The membranes had light color and good optical transmission.Their optical transmittance at 450 nm wavelength was in the range of 67%-79%,and the cutoff wavelength was in the range of 310-348 nm.They also had good thermal properties with glass transition temperature(Tg)values in the range of 264-302℃.In addition,these membranes possessed good mechanical properties with tensile strength ranging between 77.8-87.4 MPa,initial modulus ranging between 1.69-1.82 GPa,and elongation at break ranging between 4.8%-6.1%.

Cyclone separation in a supercritical water circulating fluidized bed reactor for coallbiomass gasification： Structural design and numerical analysis

A new concept of a supercritical water （SCW） circulating fiuidized bed reactor is proposed to produce hydrogen from coal/biomass gasification. The cyclone is a key component of the reactor system, in this paper, cyclones with a single circular inlet （SCI） or a double circular inlet （DCI） were designed to adapt to the supercritical conditions. We evaluated the separation performance of the two cyclones using numerical simulations. A three-dimensional Reynolds stress model was used to simulate the turbulent flow of the fluid, and a stochastic Lagrangian model was used to simulate the particle motion. The flow fields of both cyclones were three-dimensionally unsteady and similar to those of traditional gas-solid cyclones. Secondary circulation phenomena were discovered and their influence on particle separation was estimated. Analyzing the distribution of the turbulence kinetic energy revealed that the most intensive turbulence existed in the zone near the vortex finder while the flow in the central part was relatively stable. The particle concentration distribution was non-uniform because of centrifugal forces. The distribution area can be divided into three parts according to the motion of the particles. In addition, the separation efficiency of both cyclones increased with the inlet SCaN velocity. Because of its perturbance flow, the DCI separator had higher separation efficiency than the SCI separator under comparable simulations. However, this was at the expense of a higher pressure drop across the cyclone.

Experimental and numerical study of maximum efficiency vortex finder insertion depth of a Stairmand cyclone

The vortex finder is essential in cyclone separators,significantly affecting separation performance via its diameter and insertion depth.The current study shows that as the insertion depth of the vortex finder increases,the separation efficiency initially increases and then decreases,and there exists a maximum point with which the corresponding insertion depth is the maximum efficiency insertion depth(SMEID).However,there are inconsistent conclusions in the existing literature regarding the maximum efficiency insertion depth and a lack of explanation for the flow field mechanism at the maximum efficiency insertion depth.This study examines the Stairmand type cyclone using 13μm silicon micro-powder,employing numerical simulation and cold mold experiments to explore the effects of the vortex finder's insertion depth and diameter on separation performance and flow field.The results indicate that the insertion depth has minimal impact on pressure drop.The maximum efficiency insertion depth of the vortex finder decreases as the diameter decreases and is independent of this insertion depth with respect to the inlet velocity.Analysis of the flow field reveals that the maximum efficiency insertion depth is essentially the result of a"competitive and synergistic"mechanism between the annular space separation capability and the separation space separation capability.

Remarkable enhancement of gas selectivity on organosilica hybrid membranes using urea-modulated metal-organic framework nanoparticles

Metal-organic framework/organosilica hybrid membranes on tubular ceramic substrates have shown great potential for the implementation of membrane technology in practical gas separation projects due to their higher permeance compared to commercial polymers.However,the selectivities of the reported membranes are moderate.Here,we have incorporated urea-modulated metal-organic frameworks into organosilica membranes to greatly enhance its separation performance.The urea-modulated metal-organic frameworks exhibit less-defined edges of crystallographic facets and high defect density.They can be well-dispersed in the organosilica layer,which substantially suppresses the interfacial defects between metal-organic frameworks and organosilica,which is beneficial for improving the selectivity of membranes for gas separation.The results have shown that the enhanced ideal selectivity of H_(2)/CH_(4) was 165 and that of CO_(2)/CH_(4) was 43,with H_(2) permeance of about 1.25×10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) and CO_(2) permeance of 3.27×10^(−7) mol·m^(−2)·s^(−1)·Pa^(−1) at 0.2 MPa and 25℃.In conclusion,the high level of hybrid membranes can be used to separate H_(2)(or CO_(2))from the binary gas mixture H_(2)/CH_(4)(or CO_(2)/CH_(4)),which is important for gas separation in practical applications.Moreover,the simple and feasible modulation of metal-organic framework is a promising strategy to tune different metal-organic frameworks for membranes according to the actual demands.

Effect of coal particle swarm properties on the fluidization characteristics and coal beneficiation in a dense-phase gas-solid fluidized bed

This paper analyzes the influence of different coal mass fraction in an air dense medium fluidized bed （ADMFB）. The effect of the low density particles layer on heavy sedimentation increased with increasing material layer thickness. The thickness of the low density particles layer also affected the final settling time of the high densiW particles. Increasing the thickness of the low density particles layer by △h provoked an increase in the settling of high density particles that was related to their diameter （△h/D）. The pressure gradient across the bed was lower than that observed for the control experiment, which had only the dense material, owing to a decrease in the pressure gradient in Zones 1 and 5 （at the top and bottom of the bed, respectively）. Introducing different coal sizes resulted in different fluidization environments, particle accumulation layers, and changes to the surrounding zone. However, the influence of the coal particles on the local bed characteristics was related to its concentration. The feeding mass fraction of 6-13mm size and 13-25mm size coal should be limited to10% and 13%, respectively. The ranges of possible deviation were found to be 0.08-0.15 and 0.07-0.10 for the respective samples.

Characteristics of flow and liquid distribution in a gas-liquid vortex separator with multi spiral arms

Fischer-Tropsch(F-T)synthesis is an important route to achieve the clean fuel production.The perfor-mance of gas-liquid separation equipment involving in the progressive condensation and separation of light and heavy hydrocarbons in the oil-gas products has become a bottleneck restricting the smooth operation of the F-T process.In order to remove the bottleneck,a gas-liquid vortex separator with simple structure,low pressure drop and big separation capacity was designed to achieve the efficient separation between gas and droplets for a long period.The RSM(Reynolds Stress Model)and DPM(Discrete Phase Method)are employed to simulate the flow characteristics and liquid distribution in the separator.The results show that the separation efficiency is influenced by the flow field and liquid phase concentration in the annular zone.The transverse vortex at the top of spiral arm entrains the droplets with small diam-eter into the upper annular zone.The entrained droplets rotate upward at an angle of about 37.4°.The screw pitch between neighbor liquid threads is about 0.3 m.There is a top liquid ring in the top of annular zone,where the higher is the liquid phase concentration,the lower is the separation efficiency.It is found that by changing the operating condition and the annular zone height the vortex can be strengthened but not enlarged by the inlet velocity.The screw pitch is not affected by both inlet velocity and annular zone height.The liquid phase concentration in the top liquid ring decreases with both the increases of inlet velocity and annular zone height.The total pressure drop is almost not affected by the annular zone height but is obviously affected by the inlet velocity.When the height of annular zone is more than 940 mm,the separation efficiency is not changed.Therefore,the annular zone height of 940 mm is thought to be the most economical design.

Triptycene-derived heterocalixarene:A new type of macrocycle-based stationary phases for gas chromatography

This work reports the investigation of a new triptycene-derived oxacalixarene(TDOC)as the stationary phase for gas chromatography(GC)with high-resolution performance for a wide range of analytes and isomers.The TDOC scaffold is composed of triptycene and 1,8-naphthyridine moieties,inherently differing from the conventional calixarenes in structures and properties.As a result,the TDOC column exhibited outstanding column efficiency of 5679 plates/m by n-dodecane at 120℃.It showed advantageous performance for separations of the mixtures with various analytes and achieved high resolution of diverse isomers(skeletal,positional and cis-/trans-isomers)from apolar to polar nature.Moreover,the TDOC column exhibited high thermal stability up to 310℃.To date,the TDOC-based materials have not been reported in chromatography.This work demonstrates the good potential of the triptycene-derived heterocalixarenes as a new class of stationary phases for chromatographic analyses.