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.

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.

Improving Existing Drainage and Gas Recovery Technologies: An Experimental Study on the Wellbore Flow in a Horizontal Well

With the increasing number of horizontal wells with low pressure,low yield,and water production,the phenomenon of water and liquid accumulation in gas wells is becoming progressively more serious.In order to fix these issues,it is necessary to improve existing drainage and gas recovery technologies,increase the fluid carrying capacity of these wells,and ensure that the bottom-hole airflow has enough energy to transport the liquid to the wellhead.Among the many techniques of drainage and gas recovery,the gas lift has recently become a popular method.In the present study,through the simulation of the entire horizontal well,the flow regularity of the whole wellbore during the lift of low-pressure gas has been analyzed.The pressure distribution,liquid holdup rate,flow pattern,and energy loss(including gravity loss and friction loss)have been determined using the Beggs-brill approach.It has been found that the total pressure drop of the wellbore decreases first and increases gradually after reaching a minimum value when gas extraction is carried out via gas lift.Based on the analysis of the influence of the injection volume on wellbore pressure drop and the influence of flow pattern on the lifting efficiency,the optimal gas-lift injection parameters have been determined by taking the minimum pressure loss of wellbore as the judgment criterion.

Analysis of Wellbore Flow in Shale Gas Horizontal Wells

Theflow behavior of shale gas horizontal wells is relatively complex,and this should be regarded as the main reason for which conventional pipeflow models are not suitable to describe the related dynamics.In this study,numerical simulations have been conducted to determine the gas-liquid distribution in these wells.In particular,using the measuredflow pressure data related to 97 groups of shale gas wells as a basis,9 distinct pipeflow models have been assessed,and the models displaying a high calculation accuracy for different water-gas ratio(WGR)ranges have been identified.The results show that:(1)The variation law of WGR in gas well satisfies a power function relation.(2)The well structure is the main factor affecting the gas-liquid distribution in the wellbore.(3)The Beggs&Brill,Hagedorn&Brown and Gray models exhibit a high calculation accuracy.

A Pressure-Drop Model for Oil-Gas Two-Phase Flow in Horizontal Pipes

The accurate prediction of the pressure distribution of highly viscous fluids in wellbores and pipelines is of great significance for heavy oil production and transportation.The flow behavior of high-viscosity fluids is quite different with respect to that of low-viscosity fluids.Currently,the performances of existing pressure-drop models seem to be relatively limited when they are applied to high-viscosity fluids.In this study,a gas-liquid two-phase flow experiment has been carried out using a 60 mm ID horizontal pipe with air and white oil.The experimental results indicate that viscosity exerts a significant influence on the liquid holdup and pressure drop.At the same gas and liquid volume,both the liquid holdup and pressure drop increase with an increase in the viscosity.Combining two existing models,a modified pressure drop method is developed,which is applicable to horizontal pipes for different viscosities and does not depend on the flow pattern.This new method displays a high accuracy in predicting the new experimental data presented here and other published data in literature.

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.

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.

水平磁场高梯度磁选机的改进及其在攀西某钛铁矿的应用

水平磁场高梯度磁选机具有磁系不易腐蚀、磁介质不易堵塞等特点,用于钛铁矿粗选效果良好,但该型设备受磁系间距限制,分选环宽度、磁介质体积量较小,影响处理量,且激磁能耗高,需要对其进行改进,提高处理量、降低能耗。以SSS-Ⅱ-2750水平磁场高梯度磁选机为基础,对其分选环系统进行了改进,在磁系高度方向增加分选环厚度,并分成内外双层环,并对内层环配置粗介质棒的介质盒以吸附粗粒、强磁性目的矿物,对外层环配置细介质棒的介质盒以吸附细粒、微细粒磁性较弱的目的矿物,可实现梯级分选,同时,内外环均配置卸矿装置,分层卸矿,可有效保障目的矿物的卸矿效率。在攀西地区某选钛厂钛铁矿一段粗选工序考察其效果,在磁场强度0.45 T、立环转速6.2 r/min、冲程10 mm、冲次120 r/min、给矿量160t/h、原矿TiO_(2)品位10.42%的条件下,改进后的水平磁场高梯度磁选机可获得TiO_(2)品位18.55%、回收率85.78%的钛粗精矿。与改进前磁选机、垂直磁场高梯度磁选机相比,其钛粗精矿品位与其他两种设备相近,但回收率分别高8.43、13.63百分点,分选效果好,同时改进后的水平磁场高梯度磁选机的激磁能耗在三种设备中最低,为0.49 kW·h/t,表明该设备处理量大且能耗低,实现了设备改进目的。

袁家村微细粒难选磁赤混合铁矿石提铁降硅试验研究

袁家村铁矿选矿厂原生产工艺流程获得的铁精矿TFe品位仅65%左右、SiO_(2)含量达4%~5%,难以满足市场对高品质铁精矿的需求。为此,在详细分析生产流程中混合磁选精矿性质的基础上,采用卧式搅拌磨机细磨—弱磁选+强磁选—反浮选工艺流程开展了提铁降硅试验研究。对TFe品位42.44%、SiO_(2)含量35.42%的混合磁选精矿,在磨矿细度为-0.045 mm占97%情况下,全流程试验获得了产率53.87%、TFe品位67.87%、SiO_(2)含量1.96%、TFe回收率86.15%的高品质铁精矿;磨矿细度为-0.045 mm占94%情况下,适当增大捕收剂RA用量,可获得产率54.76%、TFe品位67.14%、SiO_(2)含量2.09%、TFe回收率86.63%的高品质铁精矿。研究结果可作为选矿厂提铁降硅工艺流程优化决策依据,对类似性质难选铁矿石的高效开发利用具有参考价值。

基于冲突点到达时间的航空器自主间隔控制律

在航路巡航阶段将部分间隔保持责任由管制员移交给飞行员,可在降低管制负荷的同时提升空域安全运行效率。针对新一代分布式空管模式,本机航空器基于交叉点到达时间将存在潜在冲突的目标航空器作为间隔控制目标机,构建交叉冲突中分别基于时间与空间的指定间隔值的自主间隔控制模型;以调整航空器机动飞行的校准空速作为航空器的自主间隔控制策略,通过控制本机航空器校准空速实现对两航空器间隔的有效控制。设置水平交叉冲突场景进行仿真对比实验,仿真结果表明了所提间隔控制策略用于分布式自主间隔保持的有效性及实用性。

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.

水平层状围岩离层机理研究

以南宁市东风路水平层状岩体隧道为背景,通过理论分析,研究了水平层状围岩的离层特征,分析了离层产生的条件。研究结果表明:水平层状围岩的变形是由水平应力导致的,水平应力引发岩层结构变形,最终导致围岩产生离层。相邻岩层非同步、非协调结构变形是离层产生的本质表现;水平层状围岩的离层可分为协调变形阶段、离层产生前的临界阶段、离层产生与发展阶段;从力学条件上看,离层的产生与发展仅与水平应力和岩层自重有关;用薄板理论分析了考虑岩层自重和水平应力条件下的层状围岩离层条件。

卧式分离器内气液两相流动特性数值分析

卧式分离器的基本原理是气液相存在密度差,在重力的作用下,气相上浮从排气口排出,液相沉降汇集并从排液口流出。如果液相的占比非常小时,液相多以液滴形式被气相裹挟进入分离器,这时需要波状聚结板等装置来将液滴吸附,使液滴聚并变大,脱离气相控制。为研究卧式分离器的气液分离效率及流场细节,利用CFD软件模拟了低液相含量的卧式分离器气液两相流动,给出了分离器内部的流场信息。

水平层状围岩离层特征及离层影响因素研究

以南宁市东风路水平层状岩体隧道为背景,通过理论分析和现场试验,研究了水平层状围岩的离层特征及离层影响因素。离层的形成,是由于相邻岩层间的不协调变形引起的。当相邻岩层的层厚或力学性质差异较大时,隧道围岩离层便会产生。此外,离层的产生还受到岩体结构、围岩力学特性、地应力以及洞室尺寸等因素的影响。离层的产生及发展范围还受到关键层所在位置的影响,关键层距开挖断面越近,受到关键层的支撑和阻挡作用,离层所能影响范围越小,当围岩中不存在关键层时,离层影响范围大致为洞室跨度的一半。研究对类似工程具有借鉴意义。

弓形面积结合Excel在卧式分离器计算过程中的应用

对于气液分离器的设计,一直采用的设计规范HG/T 20570.8—1995进行计算,对卧式分离器的设计要采用试差的方式,牵涉到查图,无行中增加工作量,为了节省计算时间及提高计算精度,特编制了卧式分离器的计算表格。基于此,给出了表格的形式及弓形面积公式的导出过程,并结合已经实施的项目,介绍低温甲醇洗装置一个卧式分离器的计算过程,以便详细了解各个表格的功能以及在计算过程中所注意的事项。讲解用Excel表格所编制的计算模块中各参数的计算过程及其所采用的公式。

卧式沉降离心机参数对固体回收率的影响研究

煤炭领域细粒煤泥处理属于行业煤泥处理的主要难题,卧式沉降离心机在煤炭领域上具有广泛的应用,其适用于各种固液分离,尤其应用于细粒级煤炭回收以及降低煤炭水分。为有效降低部分细煤泥处理费用,增加回收后细煤泥的增值利用,以河北、山西、内蒙古地区3个洗煤厂细煤泥为试验对象并开展离心机参数变量对固体回收率的试验研究,重点探究转鼓转速、转速差、堰高、入料质量分数和粒度组成对回收率的影响规律。试验结果表明:转速增加将提高回收率、降低分级粒径,极限转速后变化不显著;随着速度差的增加则回收率逐步增加,较高的入料质量分数下则回收率变化较小;一定范围内增加堰高有利于回收,需调整堰高至合理区间;随着入料质量分数上升则回收率逐步上升,其质量分数超过40%,回收率上升趋势变化较小;回收率随物料粒度变大而增加,而分级粒径变化很小。

新型水平带式干选磁选机研制及应用

本文介绍了新型水平带式干选磁选机工作原理、工业试验过程及结果,验证了该干选磁选机对微细颗粒磁性矿的分选效果。

卧螺离心机离心分离场速度仿真分析

针对卧螺离心机理论研究不足而造成的工作时高速堵塞和卡死等恶性事故,应用计算流体动力学(Computational fluid dynamics,CFD)的知识和目前应用较广泛的流体力学软件FLUENT,对卧螺离心机三维立体模型进行网格划分和边界条件设定,通过适当求解得出分离场轴向速度、周向速度和径向速度与结构特性参数之间的相互关系,且在此基础上对离心场中固体颗粒的运动状态进行仿真,得到其运动规律。结果表明,转鼓转动角速度的提高不利于液流的轴向流动,易造成液流滞后值相对升高。通过比较可知,选择50 rad/s的转动角速度最合理;悬浮液固体颗粒体积分数在17%时将达到沉降速度的极限,此时最有利于固液分离。通过对比可知,颗粒沉降时间与理论计算结果基本符合,这为进一步的理论研究和探索奠定了基础。

割缝衬管水平井堵水技术现状及发展趋势

割缝衬管是目前国内外水平井完井的主要方式,该类复杂结构井的堵水工作对于其整体开发效果的提高具有重要意义。对相关堵水技术现状进行了分析,指出环空封隔(ACP)定位注入技术可有效克服堵剂笼统注入的局限及风险,是适合割缝衬管水平井结构特点的堵水新思路。但目前环空封隔材料的性能尤其是触变性制约了该技术的进一步发展。在总结探讨存在问题的基础上,提出应结合国内水平井结构及施工工艺特点,建立相应技术标准,开发高性能环空封隔材料,进而为割缝衬管水平井堵水技术的发展、突破奠定基础。另外,应结合国内水平井所处油藏条件苛刻的实际,进一步开展抗温抗盐、选择性堵剂的研究。

方型卧式分离器的试验研究

为探求方型卧式分离器的性能,对它在不同运行风速和不同固体颗粒浓度下的分离效率和压降进行了试验研究.结果表明,在试验参数范围内,分离器的分离效率和压降随分离器入口风速的增加而增加,受入口颗粒浓度的影响不明显,分离效率与方型卧式分离器的出气形式有关;对粒径大于100μm的固体颗粒,方型卧式分离器的分离效率在90%以上,压降小于1000Pa.同时建立了一个计算方形卧式分离器分级效率的简单数学模型,计算结果与试验数据符合较好.