Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.

A two-step transient liquid phase diffusion bonding process of T91 steels

In this study, a two-step heating process is introduced for transient liquid phase （ TLP） diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating step is addressed to melt the interlayer, followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T9／ heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied, we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution, similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend＇s strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines. Nevertheless, the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 °C for 0. 5 min and 1 230 °C fo r 4 min.

Digital image processing of saturation for two-phase flow in planar porous media model

In this paper, the accuracy of estimating stained non-wetting phase saturation using digital image processing is examined, and a novel post-processing approach for calculating threshold is presented. In order to remove the effect of the background noise of images and to enhance the high-frequency component of the original image, image smoothing and image sharpening methods are introduced. Depending on the correct threshold, the image binarization processing is particularly useful for estimating stained non-wetting phase saturation. Calculated saturation data are compared with the measured saturation data during the two-phase flow experiment in an artificial steel planar porous media model. The results show that the calculated saturation data agree with the measured ones. With the help of an artificial steel planar porous media model, digital image processing is an accurate and simple method for obtaining the stained non-wetting phase saturation.

DIFFERENCE SCHEME FOR TWO-PHASE FLOW

A numerical method for two-phase flow with hydrodynamics behavior was considered. The nonconservative hyperbolic governing equations proposed by Saurel and Gallout were adopted. Dissipative effects were neglected but they could be included in the model without major difficulties. Based on the opinion proposed by Abgrall that “a two phase system, uniform in velocity and pressure at t=0 will be uniform on the same variable during its temporal evolution", a simple accurate and fully Eulerian numerical method was presented for the simulation of multiphase compressible flows in hydrodynamic regime. The numerical method relies on Godunov-type scheme, with HLLC and Lax-Friedrichs type approximate Riemann solvers for the resolution of conservation equations, and nonconservative equation. Speed relaxation and pressure relaxation processes were introduced to account for the interaction between the phases. Test problem was presented in one space dimension which illustrated that our scheme is accurate, stable and oscillation free.

Robust scheme for implemention of quantum phase gates for two atoms

We propose a scheme for implementing conditional quantum phase gates for two four-state atoms trapped in a cavity. The two ground states of the atoms are coupled through two Raman processes induced by the cavity mode and two classical fields. Under certain conditions nonresonant Raman processes lead to two-atom coupling and can be used to produce conditional phase gates. The scheme is insensitive to cavity decay, thermal photons, and atomic spontaneous emission. The scheme does not require individual addressing of the atoms.

车用燃料电池散热性能实验研究

质子交换膜燃料电池(PEMFC)作为能效转换率高、清洁可靠的发电装置,在交通、储能、航天及军事等领域有着广泛应用。为了解决质子交换膜燃料电池散热密度高、发热量大、散热效率低等突出问题,本文针对散热量为15 kW的质子交换膜燃料电池,设计并搭建了一套具有四种不同流程换热器的车用燃料电池散热系统实验台。分别使用两相冷却工质HFE-7100和乙二醇水溶液作为冷却工质,探究了在35℃的高温环境中,两种工质在不同流程换热器和不同工质流量下的散热性能和系统能效比(Energy Efficiency Rating, EER)。结果表明,在相同的流程下,采用HFE-7100两相散热方式相对于采用乙二醇水溶液液冷散热方式散热量提升率在81.2%~98.8%之间,系统EER提升率在68.2%~88.6%之间。且在4种不同流程下,3流程的系统散热效果和节能效果最佳,两相工质HFE-7100散热量和系统EER分别达到14.4 kW和20.5 kW/kW,液冷工质乙二醇水溶液散热量和系统EER分别达到7.7 kW和12.1 kW/kW。冷却工质流量为4 L/min时,系统节能效果较好,其两相和液冷散热系统EER分别能达到20.9 kW/kW和10.5 kW/kW。

微气泡发生器的研究与应用进展

微气泡具有体积小、稳定性高、停留时间长、比表面积大和具有较强自增压效应等优点,可以显著增加气液两相的接触面积和接触时间,强化气液两相的传质速率。目前,多种基于不同原理的微气泡发生器均可以有效产生微气泡,而不同领域利用微气泡的侧重点有所不同,因此其应用的微气泡发生技术也有所区别。本文综述了微气泡发生器在水处理过程、生物和医学领域、矿物浮选过程以及化工过程中的应用,重点阐述了各工业过程中常用的微气泡发生器类型和微气泡发生器的发泡原理,简述了各类微气泡发生器的气泡生成效果,指出了微气泡发生器的结构和操作条件对微气泡发生性能的影响,总结了各类微气泡发生器的使用条件。当下,依靠单一原理的微气泡发生技术仍具有一定的局限性,而耦合式微气泡发生器结合多种微气泡生成原理的优势,可以产生尺寸更小、分布更均匀的微气泡,因此耦合式微气泡发生器的研发对未来微气泡技术的应用具有重要意义。本文最后对微气泡发生器的应用前景、研发方向等进行了总结和展望。

亚毫米气泡和常规尺寸气泡气液两相流流动与传质特性对比

通过实验和数值模拟系统研究了亚毫米气泡鼓泡塔与常规鼓泡塔在流动和传质特性上的区别,并建立了适用于亚毫米气泡气液两相流流动和传质过程的数值模拟方法。研究结果表明,相比常规鼓泡塔,相同操作条件下亚毫米气泡鼓泡塔的气泡尺寸分布更窄,平均尺寸降至前者3%左右,气含率提高2倍以上,比表面积提高2个数量级。另外亚毫米气泡气液两相流中气液径向分布更均匀,轴向返混程度更小。亚毫米气泡鼓泡塔的相界面积是强化传质的关键控制因素,其液相传质系数虽低于常规鼓泡塔,但依靠巨大的相界面积,其体积传质系数是常规鼓泡塔的10倍左右。针对大规模鼓泡塔反应器的模拟结果也表明,亚毫米气泡可使反应器达到更均匀的气含率分布,受初始气液分布的影响小。

基于气固两相流原理的磨料池光整加工研究

为了降低工件表面粗糙度,获得光亮、平整表面的加工方法,基于气固两相流原理建立磨料池加工试验装置。采用单因素试验法分析影响加工工件表面粗糙度工艺参数最优区间,接着采用正交试验与极差分析法,以气压、温度、磨料粒径、主轴转速为影响因素,获得加工参数最优组合,最后对工件表面进行形貌分析。试验结果表明:工艺参数最优区间为气压0.45~0.65 MPa,温度300~700℃,磨料粒径160~240目,主轴转速1 000~1 200 r/min;在磨料池光整加工过程中,方管工件与圆管工件加工参数最优组合均为A2B3C3D2;表面形貌结果分析表明圆管工件整体表面质量好于方管工件。

基于CFD-DPM模拟的冷氢化工艺旋风分离器内气固两相流动及冲蚀磨损特性研究

针对冷氢化工艺混合气体-硅颗粒分离问题,以旋风分离器为研究对象,采用CFD-DPM模拟的方法,对旋风分离器内气固两相流动及硅颗粒的冲蚀磨损特性开展研究。结果表明,旋风分离器内静压与速度的分布呈现出内、外旋涡明显的差异性,在分离段靠近壁面附近,流体受器壁约束,形成向下运动的外旋涡,静压值较大;在轴线附近,静压值降至最小,流速沿径向先增大后减小,呈双峰分布,且速度分量以切向分量占优。旋风分离器内颗粒运动受粒径影响显著,粒径为75μm的较大硅颗粒在分离段沿壁面以螺旋带状运动为主,在入口环形孔间和灰斗顶部集中出现灰环,而粒径为20μm的较小硅颗粒的运动则呈现较强的随机性;受颗粒运动特性的影响,冲蚀作用在入口环形孔间顶板、灰斗顶部以及灰斗收缩段入口处相对更加严重;在分离锥段沿收缩方向均逐渐增大,螺旋灰带的出现使较大颗粒的冲蚀率分布更加集中,在螺旋灰带出现部位,粒径为75μm硅颗粒的冲蚀率约为20μm硅颗粒冲蚀率的5~7倍;在入口环形空间及灰斗内部,随机运动的较小颗粒造成的冲蚀作用更严重。研究结果可为旋风分离器的减磨设计和结构优化提供一定的理论指导。

双水相法萃取平菇蛋白及性质研究

为实现绿色高效提取平菇蛋白,本研究利用浊点法绘制聚乙二醇-硫酸铵(PEG-(NH_(4))_(2)SO_(4))双水相体系相图,以蛋白萃取浓度和萃取率为评价指标,考察了双水相体系中PEG分子量、PEG质量分数、(NH_(4))_(2)SO_(4)质量分数、平菇蛋白粗提液质量分数等因素对平菇蛋白萃取效率的影响,探究了平菇蛋白基本成分、乳化特性、起泡特性、持水持油性等性质。结果表明,通过响应面法优化双水相法萃取平菇蛋白最佳工艺条件:PEG2000质量分数为19.5%、(NH_(4))_(2)SO_(4)质量分数为22.6%、蛋白粗提液质量分数为26%。在此条件下,平菇蛋白的提取率为93.16%,上相平菇蛋白浓度为1.71 mg/mL。双水相法萃取所得平菇蛋白组成均一、粒径大小约为220.2 nm,氨基酸总含量221.46 mg/g,其中天冬氨酸(Asp)含量最多,为25.06 mg/g。平菇蛋白乳化稳定性、起泡性和持水性分别为65.22%、79.87%、2.61±0.18 g/g,与相近食品蛋白质对比,平菇蛋白具有较高的乳化稳定性、起泡性和持水性。本研究采用绿色环保、试剂低毒性的双水相法萃取了平菇蛋白,为食品工业蛋白质提取的绿色可持续发展提供一个新途径,为基于平菇蛋白开发功能食品提供研究基础。

机械搅拌下高铁赤泥熔融还原物料卷吸与分散行为

高铁赤泥经高温熔融还原后获得熔融铁水和还原渣,二者可分别作炼钢和水泥原料,实现赤泥资源化利用.针对如何突破高铁赤泥熔融还原过程中物料高效卷吸和分散的问题,利用高速摄像机和粒子图像测速仪等分析技术,研究了机械搅拌下搅拌桨类型、离底距离、偏心距、搅拌桨直径、搅拌转速对高铁赤泥熔融还原过程中流体流动状态和物料的卷吸及分散效果的影响.结果表明:VB十字桨卷吸效果较好,其卷料效果与搅拌转速呈正相关;适当增大搅拌桨直径和桨叶离底距离能增强物料卷吸效果;适当增加偏心距能改善物料的分散效果.

湿法冶金领域脉冲萃取技术与设备研究进展

脉冲萃取塔作为一种高效的液液萃取设备,是湿法冶金技术塔式萃取设备开发的重要方向之一。系统综述了脉冲萃取塔的开发过程,重点探讨了传递过程规律的研究、数学模型的构建,以及计算流体力学(CFD)在设备开发中的应用。回顾了脉冲萃取塔操作与结构参数对流体力学以及传质性能的影响,揭示了传质、传动量等过程中的规律性和影响因素。在此基础上,介绍了CFD模拟和其他计算技术的应用,进一步优化塔的设计与性能。最后,总结了脉冲萃取塔内构件和塔型式的改进方案,指出了未来研究的方向和潜在应用场景,旨在为今后的研究与应用提供有价值的参考。

基于CFD仿真的高黏发酵反应物降黏研究

为了实现农林剩余物玉米秸秆、玉米芯和小麦秸秆的一种或多种混合物的预处理浆料的快速降黏液化,笔者进行了降黏研究。笔者对混合物中物料搅拌降黏机理提出假设,并利用CFD仿真技术对搅拌器结构、物料预处理类型及液化工艺组合的搅拌降黏体系进行液固两相流非稳态数值仿真,探究了速度场、湍流场的分布情况,确定了生物反应釜结构、尺寸及降黏液化工艺,最后进行了试验验证。结果表明:当反应釜上搅拌器直径为70mm、下搅拌器直径为75 mm,物料为酸处理下平均粒径为830~1450μm的颗粒,搅拌转速为200~300r/min时,搅拌液化的效果最优;由此确定了搅拌降黏体系,试验验证效果较好。CFD仿真结果可为浓稠物料反应釜搅拌器的设计及液化糖化工艺优选提供参考。

伴生气处理工艺运行现状与节能优化分析

某油田伴生气处理工艺存在C3收率不稳定、脱乙烷塔塔顶温度波动大、运行能耗偏高等问题。针对以上问题,分析了影响DHX工艺运行稳定性的诸多因素,从参数优化和工艺调整等方面进行模拟研究和规律分析,并通过现场实施验证了调整效果。结果表明,原料气气质越富,C3收率越降低,总能耗越高;DHX塔塔顶回流存在气液两相流且压降较大,引起脱乙烷塔塔顶温度波动;当低温分离器、膨胀机出口压力和DHX塔塔顶回流温度调节到适当值时,可保证DHX工艺的产品质量和总能耗相对最优;现场验证后,月能耗从12 950 kWh降至10 487 kWh,能耗降低集中在丙烷制冷压缩机、塔顶冷凝器和塔底重沸器上。研究结果可为轻烃回收工艺的节能研究提供指导意义。

电导探针向量信号处理的泡状流参数分析

泡状流广泛存在于化工、石油、电力等工业场合,对其主要参数的测量不仅是工程设计的必须参考,也是进一步开发两相流理论模型的依据。文章提出并制作了小型四电极电导探针测量空气-水盖泡状流,可以获得局部含气率、界面面积浓度和气泡弦长,且通过已知或合理假设的界面运动方向可获得界面的指向和速度,并通过实验对比四电极电导探针和可视化两种测量方法。结果表明:两种方法具有良好的一致性,四电极电导探针简单、高效,可以准确地测量泡状流中相界面指向等参数,还能有效地解决多维两相流参数测量问题。

基于Zernike矩和FCM的管道内两相流流型识别

利用图像处理技术对传动管道两相流流型进行了识别。搭建了传动管道气液两相流实验系统。采用高速摄像机拍摄液压传动管路中气液两相流流型图像,利用图像处理技术获得图像的Zernike矩特征参数,然后结合模糊C均值聚类算法(FCM)对流型图像进行分类识别。研究结果显示,液压管路内的传动液为气液两相流,其流型为泡状流、环状流、弹状流、塞状流;在传动过程中,出现频率较高的流型是泡状流和塞状流;利用本方法对传动系统液压传动管路中的4种典型流型进行分类识别,总体识别率可达97%。本方法为管道中气液两相流的流型参数识别提供了新的途径。

Process intensification in vapor–liquid mass transfer: The state-of-the-art

The concept of process intensification(PI) has absorbed diverse definitions and stays true to the mission—'do more with less', which is an approach purposed by chemical engineers to solve the global energy & environment problems. To date, the focus of PI has been on processes mainly involving vapor/liquid systems. Based on the fundamental principles of vapor–liquid mass transfer process like distillation and absorption, there are three strategies to intensify interphase mass transfer: enhancing the overall driving force, improving the mass transfer coefficient and enlarging the vapor–liquid interfacial area. More specifically, this article herein provides an overview of various technologies to strengthen the vapor–liquid mass transfer, including application of external fields, addition of third substances, micro-chemical technology and usage of solid foam, with the objective to contribute to the future developments and potential applications of PI in scientific research and industrial sectors.

考虑扁管换热的平行流蒸发器制冷剂两相分配特性

考虑换热扁管中制冷剂的相变过程,采用SST(shear stress transm ission)k⁃ω湍流模型和Eulerian-Eulerian两相流模型对平行流蒸发器内的制冷剂两相分配特性进行研究。发现制冷剂质量流量和入口干度的增加均会导致制冷剂分配均匀性下降:当制冷剂质量流量从15g·s^(-1)增加到25 g·s^(-1),入口干度从0增加到0.3时,总流量分配不均匀指标分别升高39.4%和50.8%。适当增加出口集管内径和蒸发器长宽比有利于改善制冷剂分配的均匀性:出口集管内径增加一倍,总流量分配不均匀指标降低41.8%;长宽比从1.005增大到1.455,制冷剂分配不均匀指标降低21.6%。

超声辅助双水相提取南方红豆杉总黄酮的工艺研究

目的:利用超声辅助双水相提取南方红豆杉中总黄酮的工艺研究。方法:以聚乙二醇(PEG)和碳酸钠等构成的双价水相晶体为测量介质,以芦丁为测量标准品,采取硝酸铝和亚硝酸钠比色法实验来计测总黄酮的含量。经过正交实验、单因素实验等来分析比较和综合考查超声时间、料液体积比、溶剂体积比和温度对黄酮含量的影响。结果:红豆杉枝叶中总黄酮的最佳提取工艺条件为料液比为1∶50(g∶mL),超声溶解时间为20 min,溶剂体积浓度比等于6∶4,提取温度30℃,提取循环3次时,总黄酮产率最高。结论:结果重现性比较好,则认为该方法工艺相对稳定和可行。