Rapid and real-time analysis of multi-component dissolved gas in seawater by Raman spectroscopy combined with continuous gas-liquid separator

Rapid and sensitive detection of dissolved gases in seawater is quite essential for the investigation of the global carbon cycle.Large quantities of in situ optical detection techniques showed restricted measurement efficiency,owing to the single gas sensor without the identification ability of multiple gases.In this work,a novel gas-liquid Raman detection method of monitoring the multi-component dissolved gases was proposed based on a continuous gas-liquid separator under a large difference of partial pressure.The limit of detection(LOD)of the gas Raman spectrometer could arrive at about 14 μl·L^(-1)for N_(2)gas.Moreover,based on the continuous gas-liquid separation process,the detection time of the dissolved gases could be largely decreased to about 200 s compared with that of the traditional detection method(30 min).Effect of equilibrium time on gas-liquid separation process indicated that the extracted efficiency and decay time of these dissolved gases was CO_(2)>O_(2)>N_(2).In addition,the analysis of the relationship between equilibrium time and flow speed indicated that the decay time decreased with the increase of the flow speed.The validation and application of the developed system presented its great potential for studying the components and spatiotemporal distribution of dissolved gases in seawater.

Experimental Research on Desulfurization of Fine Coal Using an Enhanced Centrifugal Gravity Separator

A desulphurization experimental study under the effects of compounding physical force fields has been described for 〈 0.5 mm fine particles of high sulfur coal. A statistical test using the Box-Behnken Design of experiments was conducted to evaluate the effects of individual operating variables and their interactions on desulfurization of fine coal using an enhanced centrifugal gravity separator. A model describing the relation between desulphurization efficiency of pyrite sulfur and different operating variables has been designed. The interactions between different factors on the pyrite sulfur desulphurization efficiency have been analysed. The optimal test conditions for desulfarization are extracted from the Design-Expert 6.0 software. Finally, the pointed out. advantage of centrifugal gravity separation for fine coal is pointed out.

Faults Analysis and Diagnosis of DRJ-460 Dish Centrifugal Separator′s Helical Gear

The main faults of dish centrifugal separator's helical gear are described inthis paper. In order to diagnose the DRJ-460 dish centrifugal separator correctly, the vibration istested with a helical gear under both normal and abnormal conditions. After comparing severalgeneral methods of the gear's fault feature extraction, a new convenient and effective method ispresented on the basis of analyzing the vibration spectrum under different rotary velocities.

Removal of primary iron rich phase from aluminum-silicon melt by centrifugal separation

Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of AI-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in AI-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two AI-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for AI-12Si-1.7Fe alloy. And they are 82% and 18% for AI-12Si-3.4Fe alloy, respectively.

Evaluation of gas-liquid separation performance of natural gas filters

Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas. This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters used in the West-East natural gas transmission project. The comparison of the original pressure drop of clean filters and the evolution of pressure drop as liquid droplets deposited in the filter media are described. The original pressure drops of these filters were similar but the pressure drops at a steady state were different. Fractional efficiency was used to study the separation performance of cartridge filters. Droplets at the outlet of the filters had small diameters, no more than 3 μm, but were very numerous. The effect of filtration velocity on gas-liquid separation performance was analyzed. Higher filtration velocity indicated better gas-liquid separation performance. Finally the quality factor related to pressure drop and filtration efficiency was applied to evaluate the gas-liquid separation performance.

Hydrodynamic characteristics of 30%TBP/kerosene-HNO3 solution system in an annular centrifugal contactor

Annular centrifugal contactors (ACCs) have many advantages and are recognized as key solvent-extraction equipment for the future reprocessing of spent nuclear fuel (RSNF). To successfully design and operate ACCs for RSNF, it is necessary to understand the hydrodynamic characteristics of the extraction systems in ACCs. The phase ratio (R = Vaq/Vorg, A/O) and liquid holdup volume (V) of the ACC are important hydrodynamic characteristics. In this study, a liquid-fast-separation method was used to systematically investigate the effects of the operational and structural parameters on the V and R (A/O) of a φ20 ACC by using a 30%TBP/kerosene- HNO3 solution system. The results showed that the operational and structural parameters had different effects on the V and R (A/O) of the mixing and separating zones of the ACC, respectively. For the most frequently used structural parameters of the φ20 ACC, when the rotor speed was 3500 r/min, the total flow rate was 2.0 L/h, and the flow ratio (A/O) was 1, the liquid holdup volumes in the mixing zone and rotor were 8.03 and 14.0 mL, respectively, and the phase ratios (A/O) of the mixing zone and separating zone were 0.96 and 1.43, respectively.

Numerical simulation on centrifugal pump compressible flow field with different gas volume fractions

In order to study the influence of gas-liquid two-phase flow on the performance and internal flow field of a centrifugal pump,the steady three-dimensional flow with different gas volume fractions was simulated by applying the Reynolds-average N-S equation and mixture gas-liquid two-phase flow model,and the compressibility of gas was taken into consideration in the simulation. Then the centrifugal pump characteristic and the gas distribution law in different gas volume fractions were analyzed. The computational results show that gas volume fraction has a certain influence on the performance of the centrifugal pump,and the efficiency and head of the pump are on the decline with the increase of it.Static pressure in the impeller increases in the radial direction,but the pressure gradient in the flow direction is different under the different gas volume fractions. The gas volume is distributed mainly in the ipsilateral direction of impeller back shroud in the flow channel of the volute. On the suction side of the blade inlet there is an obvious low-pressure area,which causes bubbles agglutination and higher gas volume fraction. With the gas entering passage flow,gas volume fraction in the suction decreases and the pressure surface rises gradually. Higher gas volume fraction causes air blocking phenomenon in the flow passage and the discharge capacity reduces. The increase of gas volume makes the turbulent motion within the impeller more and more intense,which leads to more and more energy loss.

Numerical modeling of centrifuge cyclic lateral pile load experiments

To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.

Advances in Centrifugal Separators for Particulate Matter Control from Stationary Sources

This paper summarized recent developments in centrifugal separators for particulate matter (PM) emission control. Airborne particulate matter, which is responsible for many health and environmental problems, is generated mostly from combustion processes in stationary sources such as house burners and power plants and other production facilities, except field dust. Reverse flow cyclones are centrifugal separators having been widely used for industrial particulate matter removal. Typical pressure drops of these cyclones for air cleaning are 500 Pa or higher, and were believed to be only able to separate particles larger than 10 μm. An aerodynamic deduster that could separate particles as small as 1μm at a pressure drop of 200 Pa was recently developed. Field evaluation showed that the deduster can be effectively used in reducing particulate matter emission from stationary sources.

Size Depending Separation of HAP:Eu Nanoparticles in Dispersed Sol

The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydroxyapatite nanoparticles （HAP） are doped with the luminescent rare earth elemeat Europium （Eu）, the panicle size becomes larger compared to pure HAP. Hence, a panicle size reduction is necessary to achieve similar experimental conditions when stbstituting pure HAP with luminescent HAP ： Eu nanoparticles to investigate particlecell-interactions in cell culture experiments. While the sedimentation process of particles in liquids and gels has been well described in literature, the separation of particles in dispersed colloids has not been studied, yet. In this study, the size depending separation and particle size redaction of a homogeneous dispersed nanoparticle sol by gravity and centrifugation were investigated. As the results showed, shorter time of centrifugation at higher speed can reduce the average particle size compared to the decline of the panicle concentation in the upper sol layer most efficiently. This ceatrifugation method has some similarity to the overspeeding technique which is commonly used to lower the transient time to reach the equilibrium of sedimentation.

FLUID DYNAMICS IN A GAS-STIRRED LADLE——A Separated Flow Model with Stochastical Trajectories

A separated flow model with stochastical trajectories has been developed to describe the fluid flow in a bubble stirred ladle.The bubble dispersion,turbulent characteristics and gas-liquid interactions can be predicted by this mathematical model.The bubble flow as a dispersed phase is treated in a Lagrangian frame of reference and the analysis of the turbulent flow for liquid phase is conducted in a Eulerian field.The interactions between bubbles and liquid phases are considered as a bubble source term in the control equation for a continuous phase. The Monte Carlo sampling method is used to determine the bubble trajectories.The homoge- neous flow model is also taken into consideration so that it can be compared with the sepa- rated flow model.Numerical predictions using a water model of a ladle show that the pre- dicted results of the separated flow model agree satisfactorily with the experimental results, but the prediction of the homogeneous flow model are not in good agreement with the experi- mental results.

超重力强化分离铜渣中铜的数值模拟及辅助工业设计

由于当前铜冶炼工艺产生的铜渣铜含量比较高,采用传统的电炉贫化技术分离铜液滴时间长、回收率低,因此引入超重力技术对贫化过程进行改善。采用数值模拟的方法,以卧式离心机为模型基础,选用转炉铜渣作为试验对象进行研究,借助COMSOL Multiphysics软件构建模型,模拟铜渣中铜液滴的沉降过程。根据计算结果分析重力系数(G)、温度(T)对不同粒径铜液滴沉降行为的影响。结果表明,在T=1300℃、G=1的条件下,粒径低于80μm的铜液滴无法自由沉降;在恒定温度下,重力系数以及铜液滴粒径的增加均有利于铜液滴在铜渣中的沉降;温度升高会降低铜渣和铜的黏度,促进二者分离。最后,根据铜液滴的沉降数据,对离心机半径、给料速度等工业参数提出优化建议,以提升铜的回收率,降低企业生产成本。

浅析管式分离机的制动装置

管式分离机多数机型需要停机后进行人工卸料,多数管式分离机制动是切断电源后再停车,存在停机时间较长的问题。为进一步提高管式分离机的分离效率,对管式分离机的制动装置进行探讨。阐述了离心机的机械制动、电磁制动、液压制动、液力制动和变频制动等方式,分析了各种制动装置在管式分离机上的应用可能性及其应用状况。为实现连续生产降低人工成本、避免对管式分离机机体的拆卸,可通过自动卸料装置的研制,来解决频繁停机后需人工卸料的问题。

离心超重力油水分离器流场特性的数值模拟研究

随着油田开采逐渐进入高含水期,对油水分离器的性能要求也愈发严格,现有油水分离器已很难达到分离要求,油水分离领域亟需新的研究进展。通过数值模拟的方法对一种新型离心超重力油水分离器流场特性进行了研究。从流动参数、结构参数以及物性参数3个方面探究不同参数对分离器分离性能及流场特性的影响规律。研究结果表明:各含水体积分数情况下该分离器分离效果都较好,油出口分离效率随着含水体积分数上升而减小,且含水体积分数较高时水出口的含油量较低;随着入口流量的增大,水出口含油量不断增大,油出口分离效率先减小后基本不变;随着电机转速的增大油出口分离效率先增大后基本不变,电机转速为500 r/min时,油出口分离效率为82%,电机转速为1500 r/min时,油出口分离效率增大至97%;在模拟范围内叶片数量与分离效果呈正相关;油密度和油黏度与分离器分离效果均呈负相关,其值越大分离效果越差。研究结果可为离心超重力油水分离器的实际应用提供理论指导。

离心萃取分离钒页岩酸浸液中钒铁的研究

离心萃取法是通过高速转动提高两相间的传质,并利用离心力场来实现两相快速分离的萃取方法。为提高萃取剂对钒(V)的萃取效率,强化V(IV)与Fe(II)的分离效果,本研究将离心萃取法应用于钒页岩酸浸液中钒的净化富集工艺。结果表明,在萃原液初始pH值2.0、有机相组成15 vol.%P204+85 vol.%磺化煤油、相比(O/A)1∶4、萃取时间4 min、萃取温度45℃、转速1 400 r/min的离心萃取条件下,V萃取率为87.67%。与常规萃取相比,离心萃取使V/Fe分离系数由41.78提升至127,钒的萃取饱和容量由52.63 g/L提升至70.45 g/L,表明离心萃取可有效强化钒铁分离效果,并提高钒的萃取饱和容量。

A Parametric Study for High-Efficiency Gas-Liquid Separator Design

A gas liquid centrifugal separator is widely used in industry on account of its simple geometry and little maintenance. These separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, lower pressure drop and higher capacity. A gas liquid centrifugal separator is a device that utilizes centrifugal forces and low pressure caused by rotational motion to separate liquid from gas by density differences. Efficient and reliable separation is required for the optimum operation. These separators are often operated at less than peak efficiency due to the entrainment of separated liquid through an outlet pipe which is closely associated with the very complicated flow phenomena involved. Design parameters such as length of the separation space, vane exit angle, inlet to outlet diameter ratio, models for separation efficiency and pressure drop as a function of physical dimensions are not available in literature. This leaves the designer with very little to go on except known designs and experimentation. The aim of present study is to perform a parametric study to get higher efficiency for gas-liquid separator. A parametric study has been carded out with the help of CFD tools to analyze a separation performance of a centrifugal separator by varying the length of separator space. The best design parameters are analyzed based upon obtained results, tangential velocities, vortices, total pressure losses. From the present study several attempts are made to improve the performance of conventional centrifugal separators.

新型离心干式磁选机预选细粒磁铁矿石粉料的分选机理与试验

针对现有干式磁选法无法有效分选细粒铁矿石粉料的难题,基于磁场-离心场协同作用原理开发了一种新型离心干式磁选机。首先,介绍该磁选机的工作原理,分析矿粒在离心干式磁选过程中的受力情况;然后,进行分选0~2.0 mm粒级占74.97%的细粒磁铁矿石粉料试验;最后,分析磁选精矿产品并评估该磁选机的分选效果。研究结果表明:磁偶极子力的主导性随矿粒直径减小而增加;当矿粒直径小于0.096 mm时,磁偶极子力成为离心干式磁选的第一主导力,易引起脉石夹带;该磁选机在工作过程中,分选锥旋转产生的切向摩擦力持续有效分散矿石粉料,以螺旋运动形式延长了运动路径,可以降低分选粒度下限;提高分选锥转速和降低磁感应强度,精矿产率和回收率减少,精矿和尾矿铁品位上升;该磁选机能高度选择性分选细粒磁铁矿,在分选锥转速为60 r/min、磁感应强度为0.21 T条件下一次分选,将试样全铁(TFe)和磁性铁(MFe)品位由33.60%和28.57%分别提升至44.53%和40.73%,TFe和MFe回收率分别达到90.38%和97.23%,尾矿TFe和MFe品位分别仅为10.16%和2.49%;该磁选机对该磁铁矿的分选粒度下限达到0.045 mm以下。

高含水采出液管式预分水技术研究进展

油田受长期注水开发的影响,已进入高含水开发期。为应对随着含水量增加,导致原有设备运行负荷不均匀、运行能耗不断上升等问题,综述了多种不同原理的预分水技术,分析了重力式、离心式以及破乳技术的工作原理、优势与局限性,说明了预分水技术的处理效果及其对油田发展的重要性,展望了高含水采出液管式预分水技术未来发展的方向。

云南某选锡尾矿中锡回收选矿试验研究

试验原料来自云南某锡多金属矿选厂的选锡尾矿,尾矿中锡品位为0.35%,是主要的有价金属。尾矿中锡主要以锡石形式存在,锡石占有率为72.39%,该尾矿中细粒级含量高,其中-0.02mm粒级含量高达67.11%,该粒级的锡占有率为68.00%,通过传统浮选及摇床工艺较难回收。针对该尾矿细粒级含量高的特点,确定离心重选为主要工艺,一段离心重选能获得锡品位1.27%、回收率70%的锡粗精矿;经两段精选后,能获得锡品位4.11%、回收率54.10%的锡精矿。采用离心重选(一粗一精)+摇床重选(二次精选)的组合工艺,能获得锡品位17.57%、回收率17.25%的锡精矿。研究表明,采用全离心重选工艺,可获得高回收率的锡精矿产品;采用离心+摇床重选的组合工艺,可获得高品位的锡精矿产品,最终可根据实际需求,确定适合的工艺,能实现该锡资源的二次开发利用。

Temporal Behaviour of a Corner Separation in a Radial Vaned Diffuser of a Centrifugal Compressor Operating near Surge

The temporal behaviour of a flow separation in the hub-suction side comer of a transonic diffuser is studied thanks to unsteady numerical simulations based on the phase-lagged approach. The validity of the numerical re- sults is confn＇med by comparison with experimental unsteady pressure measurements. An analysis of the instan- taneous skin-friction pattern and particles trajectories is presented. It highlights the topology of the separation and its temporal behaviour. The major result is that, despite of a highly time-dependent core flow, the separation is found to be a ＂fixed unsteady separation＂ characterized by a fixed location of the main saddle of the separation but an extent of the stall region modulated by the pressure waves induced by the impeller-diffuser interaction.