Numerical simulation of slurry jets using mixture model

Slurry jets in a static uniform environment were simulated with a two-phase mixture model in which flow-particle interactions were considered. A standard k-ε turbulence model was chosen to close the governing equations. The computational results were in agreement with previous laboratory measurements. The characteristics of the two-phase flow field and the influences of hydraulic and geometric parameters on the distribution of the slurry jets were analyzed on the basis of the computational results. The calculated results reveal that if the initial velocity of the slurry jet is high, the jet spreads less in the radial direction. When the slurry jet is less influenced by the ambient fluid (when the Stokes number St is relatively large), the turbulent kinetic energy k and turbulent dissipation rate ε, which are relatively concentrated around the jet axis, decrease more rapidly after the slurry jet passes through the nozzle. For different values of St, the radial distributions of streamwise velocity and particle volume fraction are both self-similar and fit a Gaussian profile after the slurry jet fully develops. The decay rate of the particle velocity is lower than that of water velocity along the jet axis, and the axial distributions of the centerline particle streamwise velocity are self-similar along the jet axis. The pattern of particle dispersion depends on the Stokes number St. When St = 0.39, the particle dispersion along the radial direction is considerable, and the relative velocity is very low due to the low dynamic response time. When St = 3.08, the dispersion of particles along the radial direction is very little, and most of the particles have high relative velocities along the streamwise direction.     

印染退浆废水制备水煤浆的实验研究

利用印染退浆废水制备了水煤浆,研究了印染生产中两种退浆剂NaOH和H2O2与淀粉、聚乙烯醇(PVA)、聚丙烯酰胺(PAM)3种不同浆料产生的退浆废水对水煤浆成浆性能的影响.结果表明,NaOH作为退浆剂时,3种浆料废水制备的水煤浆黏度随着NaOH浓度的增加,呈现先升后降再升的趋势,且NaOH浓度为3.9～5.0g/L时3种退浆废水水煤浆黏度最大,而NaOH浓度为7.0～11.0g/L时水煤浆黏度最小;在NaOH和H2O2联合作用退浆时,随着H2O2的加入,3种水煤浆的黏度先速降后趋平缓,在H2O2浓度为2.5～6.5g/L时,3种水煤浆黏度出现相似较低值.     

疏水改性聚丙烯酰胺的制备及其对难沉降尾矿的絮凝性能研究

摘要：采用水溶液共聚法,以甲基丙烯酸甲酯和丙烯酸丁酯为疏水单体,以K2S20。一NaHs03氧化还原体系为引发剂,制备了疏水改性型聚丙烯酰胺,探讨了改性单体用量对改性聚丙烯酰胺的分子量、不溶物含量、溶解速率等性能的影响规律,并对其在两种难沉降尾矿中的絮凝效果进行了评价．研究结果表明：疏水改性聚丙烯酰胺对不同类型的难沉降尾矿浆表现出不同的絮凝效果．     

软硬相隔土层中超深地下连续墙的施工技术

超深地下连续墙的施工技术在我国已有很大的发展,但是超深地下连续墙在软土条件下的施工还不是很成熟.以天津滨海新区于家堡地区某深基坑实际工程为例,对其特殊地质条件下超深地下连续墙的施工技术进行了分析和总结,得出的施工技术和处理措施能够解决该地区类似工程的施工问题.     

腐植酸钾-磺化沥青低固相泥浆在北衙金矿的应用

针对北衙金矿区钻探施工中遇到的水敏性复杂地层缩径、坍塌严重以及孔内事故频发问题,通过分析失水量与处理剂的关系,黏度与KHm(腐植酸钾)、SAS(磺化沥青)加入量的关系,从防塌浸泡试验中优选出KHm-SAS低固相泥浆体系配方。该配方经过生产实践,在水敏性复杂地层钻进时,缩径、坍塌问题得到明显改善,孔内事故率大幅降低,取得了良好的应用效果。     

水煤浆管道输送模型

本文介绍了描述加压气化用水煤浆管道流动性能的数学模型－Ｍｅｔｚｎｅｒ－Ｒｅｅｄ通用计算法。在试验范围内（Ｒｅ＇＝１６．８￣１７６０），用该模型处理２８５个实验数据的平均相对误差为６．９６％，管道输送试验可评价各种水煤浆的管道流动性能并提供管道输送参数。     

ZrO2—Al2O3系浆料性能的研究

本文研究了加入高分子电解质——聚丙烯酸(PAA),对于pH值在中性范围内ZrO_2-H_2O、Al_2O_3-H_2O系统的流变和动电特性的影响。根据胶体化学基础知识,利用计算机对实验数据进行分析、处理并设计实验。讨论了PAA在氧化物表面的吸附机理及其饱和吸附量,找到了一种确定ZrO_2-Al_2O_3双组分浆料稳定悬浮条件的新方法。     

流量计在大型水煤浆制氨装置上的选型及应用

结合水煤浆加压气化制合成氨的工艺流程和特点，提出流量计选型和安装时着重考虑的问题，介绍流量计在渭河化肥厂合成氨装置上的应用情况。     

Spray pyrolysis synthesis of nanostructured LiFexMn2−xO4 cathode materials for lithium-ion batteries

A series of partially Fe-substituted lithium manganese oxides LiFe_xMn_2−xO₄ (0 ≦ x ≦ 0.3) was successfully synthesized by an ultrasonic spray pyrolysis technique. The resulting powders were spherical nanostructured particles which comprised the primary particles with a few tens of nanometer in size, while the morphology changed from spherical and porous to spherical and dense with increasing Fe substitution. The densification of particles progressed with the amount of Fe substitution. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns.The as-prepared powders were then sintered at 750 °C for 4 h in air. However, the particles morphology and pure spinel phase of LiFe_xMn_2−xO₄ powders did not change after sintering. The as-sintered powders were used as cathode active materials for lithium-ion batteries, and cycle performance of the materials was investigated using half-cells Li/LiFe_xMn_2−xO₄. The first discharge capacity of Li/LiFe_xMn_2−xO₄ cell in a voltage 3.5-4.4 V decreased as the value x increased, however these cells exhibited stable cycling performance at wide ranges of charge-discharge rates.     

油井水泥降失水剂SPS的制备和性能研究

通过磺化改性,制备了磺化聚苯乙烯(SPS)作为油井水泥降失水剂.研究了反应条件对SPS磺化度的影响、SPS的磺化度与失水控制的关系、SPS水泥浆体系的性能.实验结果表明:在相同的条件下,磺化度越高,失水控制越好;在最佳条件下制备的SPS具有良好的降失水性能,SPS的水泥浆体系具有良好的流变性能和较好的耐温性能;在120℃下,其水泥浆体系的稠化时间,用常用的缓凝剂可调整到337 min,SPS对水泥浆其他性能无不良影响.