Influence of coke structure on coke quality using image analysis method

The quality of coke affects the performance of the blast furnace, factors affecting coke quality include coal properties, coal charge granulometry and carbonization conditions. The coke properties in elude the size analysis, cold strength (Micum Indices-M4(). MI0) and hot strength (Coke Reactivity Index-CRI, Coke Strength after Reaction-CSR) properties and structural properties such as coke structure and texture. Structural properties comprise the porosity, pore-cell wall thickness and pore sizes, while textures consist of the carbon forms in the coke. In present work, advanced method such as image analysis method was used to interpret coke microstructure. Conventional methods such as determination of coke porosity by measurement of real and apparent density and mercury porosimetry have a number of limitations. Coke size, magnification, number of image frames captured, process of pellet preparations and coke properties such as M4(), M|0, CRI and CSR (low, medium and high values) were taken as variables for experimental purposes. The coke structure parameters such as porosity, length, perimeter, breadth, roundness, pore-wall thickness and pore size distribution of the pores were determined by image analysis method. This method provided average porosity in addition to pore-wall thickness and pore-size distribution. The pore wall thickness measuremenl by image analysis method provided significant correlations with M40, CRI and CSR values. This explained the usability of image analysis for coke structure measurement.

Fine quantitative characterization of high-H2S gas reservoirs under the influence of liquid sulfur deposition and adsorption

In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments.Fine quantitative characterization of the cores in three steady states(original,after sulfur injection,and after gas flooding)was carried out using the nuclear magnetic resonance(NMR)transverse relaxation time spectrum and imaging,X-ray computer tomography(CT)of full-diameter cores,basic physical property testing,and field emission scanning electron microscopy imaging.The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1000μm.Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces,and causes greater damage to reservoirs with poor original pore structures.The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics.The worse the pore structure,the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption,and the stronger the heterogeneity.Liquid sulfur deposition and adsorption change the pore size distribution,pore connectivity,and heterogeneity of the rock,which further changes the physical properties of the reservoir.After sulfur injection and gas flooding,the permeability of TypeⅠreservoirs with good physical properties decreased by 16%,and that of TypesⅡandⅢreservoirs with poor physical properties decreased by 90%or more,suggesting an extremely high damage.This indicates that the worse the initial physical properties,the greater the damage of liquid sulfur deposition and adsorption.Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence,cobweb,or retinitis,causing different changes in the pore structure and physical property of the reservoir.

Si-MCM-41的合成及其影响因素

采用碱性水热合成方法制备Si-MCM-41,借助X射线衍射、N2吸附-脱附等表征手段系统研究晶化温度、晶化时间和碱量对其长程有序结构的影响。实验结果表明,随着碱用量的增加,产物的长程有序结构逐渐完善,但n(TMAOH)/n(SiO2)=0.68时,必须通过晶化过程中对pH值进行调节才可得到规整性更好的MCM-41。当n(TMAOH)/n(SiO2)=2时,MCM-41的X射线衍射特征峰强度变小,长程结构有序度降低。碱用量高会对比表面积产生负面影响,适宜的碱用量为n(TMAOH)/n(SiO2)=0.3。通过考察六方晶相的生长和完善以及孔壁的厚度、比表面积等因素,确定晶化时间为5 d。温度升高导致六方骨架上的硅物种缩聚速度增大,在150℃的水热合成环境中,MCM-41的长程有序结构遭到破坏,较理想的晶化温度为120℃。

晶化时间、模板剂对Si-MCM-41结构的影响

以有机硅为硅源,采用碱性水热合成制备Si-MCM-41,借助XRD,N2吸附-脱附表征手段系统研究晶化时间、模板剂对其长程有序结构的影响.结果表明:晶化过程中必须调节体系的pH,样品的六方晶相才会随晶化时间的增长而不断地生长和完善.长时间的晶化有利于孔壁增厚,对于提高Si-MCM-41的稳定性是有利的,但同时比表面积呈现下降趋势.综合考虑六方有序结构的生长和完善以及孔壁的厚度、比表面积等因素,确定晶化时间为120 h.增加模板剂(template)浓度会促进Si-MCM-41孔结构形成和排列的规整性,当模板剂为c(template)/c(SiO2)=0.7,六方有序度下降,适宜的c(template)/c(SiO2)应为0.5.

水分对木材细胞壁孔隙结构影响研究进展

木材是一种具有多级孔隙结构的天然可再生资源,其孔隙构造尤其是细胞壁孔隙结构至关重要。细胞壁孔隙结构的研究是木材加工的理论基础,对于提高木材综合利用率具有重要的现实意义。本文简要介绍了木材孔隙的种类及其表征技术,在此基础上梳理了水分对木材细胞壁孔隙结构影响的相关研究成果,总结了目前由水分引发的木材细胞壁孔隙结构变化领域仍存在的一些问题与挑战,对未来的发展方向及其前景进行展望,以期为深入揭示木材与水分的相互作用提供参考。

S型薄壁管结构振动噪声主动控制的研究

针对管状结构在航空航天某些应用场合中振动、噪声过大的实际情况,进行了振动、噪声控制实验研究。以某S型薄壁管结构模型为研究对象,利用压电智能结构,结合振动主动控制技术和FX-LMS自适应滤波算法,成功实现了振动噪声主动控制。实验结果表明,所采用的方法对此S型薄壁管结构的振动、噪声抑制的有效性。

纳米C-S-H对矿粉-水泥体系水化的影响

C-S-H是通用硅酸盐水泥主要的水化产物,对水泥基材料的性能起着十分重要的作用,但水泥水化产物复杂,难以从水化产物中分离出纯净的C-S-H并研究其对水泥基材料的影响。故本文通过双分解法制备了纳米C-S-H(NC)颗粒,并将其掺入矿粉-水泥体系中,通过无接触式电阻率测定仪、X射线衍射仪、差热分析仪(DSC-TG)、扫描电镜、压汞测试仪(MIP)等探究了NC对矿粉-水泥体系水化的影响。研究发现,在1%~4%(质量分数)掺量范围内,掺入NC可缩短基体的凝结时间,并为水泥早期水化提供更多的活性位点,加速水化产物的形成和沉淀,促进水化产物之间的搭接,从而降低了基体孔隙率并使基体早期强度和水化浆体电阻率均有所提升。

蒸汽养护条件下甲酸钙/纳米C-S-H复合对粉煤灰-水泥体系早期水化的影响

本文研究了蒸汽养护条件下,甲酸钙/纳米C-S-H(NC)复合对粉煤灰-水泥体系早期抗压强度的影响,并结合XRD、DSC-TG、MIP、SEM及FTIR等手段分析了其影响机理。结果表明:蒸汽养护条件下掺入甲酸钙能显著提高粉煤灰-水泥体系的早期抗压强度,且掺量为1.5%(质量分数)时效果最佳;甲酸钙能促进水泥和粉煤灰水化,提高水化产物的生成速率,降低粉煤灰-水泥体系的孔隙率和总孔容;在掺入甲酸钙的基础上掺入NC可进一步提高体系抗压强度,且随着NC掺量的增加而提高;NC能促进水化产物生成,提升水化程度,细化孔结构,提高体系致密度。

Pore structure of SWNTs with high hydrogen storage capacity

This paper reveals, by analyses of nitrogen cryo-adsorption isotherm, the energetic and structural heterogeneity of single-walled carbon nanotubes (SWNTs) which has a high hydrogen storage capacity. It was found that SWNTs had manifold pore structures and distributed surface energy. By comparison of the pore structures and energy distributions of SWNTs before and after hydrogen adsorption, it is preliminarily indicated that hydrogen adsorption occurred in micropores and mesopores with smaller diameter, and that the pores of different diameters determined different hydrogen adsorption processes and underwent different structure changes during hydrogen adsorption.

Design optimization of the S-frame to improve crashworthiness

In this paper, the S-frames, the front side rail structures of automobile, were investigated for crashworthihess. Various cross-sections including regular polygon, nonconvex polygon and multi-cell with inner stiffener sections were investigated in terms of energy absorption of S-frames. It was determined through extensive numerical simulation that a multi-celI S-frame with double vertical internal stiffeners can absorb more energy than the other configurations. Shape optimization was also carried out to improve energy absorption of the S-frame with a rectangular section. The center composite design of experiment and the sequential response surface method （SRSM） were adopted to construct the approximate design sub-problem, which was then solved by the feasible direction method. An innovative double S- frame was obtained from the optimal result. The optimum configuration of the S-frame was crushed numerically and more plastic hinges as well as shear zones were observed during the crush process. The energy absorption efficiency of the structure with the optimal configuration was improved compared to the initial configuration.

Chloride-binding capacity of mortars composed of marine sand subjected to external chloride penetration

In order to explore the interactional relations of internal chloride and external chloride-binding amongst the cementitious materials,the chloride-binding capacity of mortars composed of marine sand(MS)or washed marine sand(WMS)were investigated.Results indicate that more external chloride can penetrate and diff use more deeply into the WMS mortar than that in the MS mortar.This phenomenon suggests that the external chloride migration resistance due to WMS is lower than that caused by MS.The distribution trends of the bound chloride content in the two types of mortars are the same at diff erent immersion times.However,a signifi cantly decreased area of the bound chloride content exists at the border of the external penetration area(EPA)and the external unaff ected area(EUA)at the immersion ages of 3 and 7 d,and then it disappears gradually with immersion time.The WMS mortar can bind more external chloride,whereas the MS mortar can bind more internal chloride,at diff erent immersion times.The distributions of bound chloride conversion rate in the EPAs of the two types of mortars diff er across immersion times.The distribution fi rstly decreases,and then it increases at the immersion ages of 3 and 7 d.The distribution was from increase,then decreases,and increase again at the immersion ages of 28 and 56 d.The bound chloride conversion rate in the WMS mortar is aff ected more greatly by external chloride penetration than that in the MS mortar.The amounts of the Friedel’s salt tend to increase with prolonged immersion time.Finally,the penetration of external chloride can increase the amount of fi ne capillary pores smaller than 100 nm in the WMSmortar exposed for 56 d in the chloride salt solution(WMS-E)specimen.

Fractal Characteristics of Microporous Adsorbents

The traditional version of the theory of volume filling of micropores was used for the estimation of the fractal dimension of microporous solids. For this purpose, the Dubinin’s integral equation was solved for infinite and limited integration limits. The results were applied to the adsorption of nitrogen (T = 78 K) on coal samples and Davisil F silica and to the adsorption of water (Т = 293 К) on lunar soil sample and on rice starch.

表观密度与孔结构对微孔混凝土性能的影响

采用料浆容重法进行配合比设计,分别制备了表观密度为600、800、1000、1200 kg/m^(3)的微孔混凝土,并研究了表观密度与孔结构对微孔混凝土性能的影响。结果表明,所制备的微孔混凝土抗压强度在1.68~10.57 MPa之间,导热系数在0.081~0.140 W/(m·K)之间,吸水率在29.76%~48.16%之间,且微孔混凝土的表观密度对上述性能的影响具有明显的规律性。孔结构测试结果表明,孔隙率、孔分布均匀性、平均孔径大小等因素对微孔混凝土性能也有一定的规律性影响。

PVA纤维橡胶混凝土力学性能及微观特征分析

为探究PVA纤维对橡胶混凝土力学性能和界面微观特征的影响,通过轴心抗压试验和抗折试验对不同纤维掺量下橡胶混凝土的破坏形态、抗压强度和抗折强度进行了对比分析,并采用扫描电子显微镜(SEM)和能谱分析技术(EDS)对其微观形貌和界面过渡区进行了研究。结果表明:掺入PVA纤维可以有效缓解橡胶混凝土强度的衰减趋势,最佳掺量控制在1%左右,试件抗压破坏模式由脆性破坏转变为延性破坏,应力应变曲线下降段更加平缓。橡胶颗粒减小了混凝土界面受荷面积,改变了集料与水泥基体界面处的元素含量,导致混凝土强度降低。掺入PVA纤维会降低橡胶混凝土的Ca/Si比值,较基准混凝土降低幅度为5%~10%,界面黏接处C-S-H的生成量有所提高,有效地改善了橡胶混凝土内部界面缺陷。

基于糠醇改性的木材细胞壁孔隙变化对水分的影响

【目的】为进一步分析木材细胞壁与水分之间的相互作用,探究了糠醇改性前后木材细胞壁在典型水分状态下物理环境(孔隙)的变化规律和细胞壁水分的结合状态。【方法】以速生青杨为研究对象,利用糠醇改性改变木材细胞壁水分存在的物理环境,分别利用扫描电镜、激光共聚焦显微镜、傅里叶红外光谱和氮气吸附法考察绝干状态下改性材的微观形貌、改性剂分布、官能团和孔隙结构,并利用差示扫描热孔计法和二维低场核磁共振技术分析低湿、气干、高湿和纤维饱和状态下改性前后木材细胞壁物理环境的变化规律以及细胞壁水分的结合情况。【结果】糠醇改性后木材的质量增长率、体积增长率分别为35.1%和12.6%,并伴随细胞壁增厚现象。改性后木材细胞壁的比表面积和孔体积分别降低了29.9%、35.3%,糠醇树脂堵塞了木材细胞壁的部分孔隙。从低湿状态到纤维饱和状态,未处理材和改性材孔体积均呈现增加趋势,未处理材细胞壁孔径分布极大值从3.41 mm^(3)/g增加到5.65 mm^(3)/g,增加了65.7%,糠醇改性材细胞壁孔径分布极大值从2.99 mm^(3)/g增加到4.63 mm^(3)/g,增加了54.9%。在不同水分状态下,糠醇改性材的细胞壁孔体积均低于未处理材,并且在高湿环境下,水分对木材细胞壁孔体积影响更加明显。随着相对湿度升高,未处理材和糠醇改性材的含水率都增加,但是糠醇改性材含水率低于同等条件下的未处理材,吸湿性降低。含水率增加,未处理材和糠醇改性材细胞壁水分T_(1)/T_(2)值降低,水分移动性增加。糠醇改性材中两种细胞壁水分的T_(1)/T_(2)值远高于未处理材,进一步说明糠醇改性改变了木材细胞壁的物理环境,限域空间束缚增加使得水分子移动性降低。【结论】经糠醇改性后,糠醇树脂进入木材细胞壁并发生原位聚合,造成在绝干、低湿、气干、高湿、纤维饱和状态下,改性材细胞壁孔体积均低于未处理材,并且在高湿度状态下,孔体积表现出更大的增长率。物理环境的变化造成木材细胞壁容纳水分的空间减少,同时,水分子受到细胞壁的物理束缚增加,移动性降低。

高尚堡油田高3102断块沙三2+3亚段中低渗透储层可动流体赋存特征及其影响因素

为了明确中低渗透储层可动流体赋存特征,以期更好地指导油田增储上产,以高尚堡油田高3102断块沙三2+3亚段中低渗透砂岩储层为研究对象,基于薄片资料、全岩衍射分析、高压压汞曲线、密闭取心核磁共振资料、扫描电镜以及油水相渗曲线,开展了不同孔隙结构储层可动流体的赋存特征及其影响因素研究。结果表明:①不同孔隙结构储层可动流体饱和度差异较大。Ⅰ类中孔中喉型储层核磁共振T2谱呈左低右高双峰型,可动流体饱和度平均61.14%;Ⅱ类中小孔细喉型储层核磁共振T2谱呈左高右高双峰型,可动流体饱和度平均45.24%;Ⅲ类细孔微喉型储层核磁共振T2谱呈左高右低双峰型,可动流体饱和度平均30.45%;Ⅳ类微孔微喉型储层核磁共振T2谱呈左高单峰型,可动流体饱和度平均13.86%;②储层宏观物性、微观孔隙结构、黏土矿物含量以及储层润湿性共同控制可动流体赋存特征。其中微观孔隙结构是可动流体赋存的关键因素,孔喉半径越大,储层渗流能力越好,黏土矿物含量越低,储层润湿性越弱,可动流体饱和度越高。该研究结果对高尚堡油田沙三2+3亚段储层高效注水开发提供合理科学依据。

准噶尔盆地吉木萨尔凹陷二叠系芦草沟组储层介-宏孔孔隙结构特征及控制因素

吉木萨尔芦草沟组页岩油资源潜力巨大,为探究其储层介-宏孔孔隙结构特征及控制因素,以研究区芦草沟组钻井岩心为对象,利用X射线衍射、铸体薄片、扫描电镜、孔渗测试、高压压汞、氮气吸附、分形理论、相关性分析等方法,对其储层特征、孔隙结构及控制因素进行了讨论。研究发现:1)研究区芦草沟组储层是一套以长英质碳酸盐岩(A岩)、长英质黏土岩(B岩)、灰/云质细粒长英沉积岩(C岩)、混积岩(D岩)为主的低孔-特低孔、特低渗储层,主要孔隙类型为溶孔,此外还发育有剩余粒间孔、晶间孔、微裂缝;2)研究区芦草沟组储层孔隙分布复杂,孔径分布曲线呈现多峰形,介孔提供了大部分孔容和比表面积;高压压汞计算的宏孔分形维数均值和氮气吸附计算的介孔分形维数均值分别为:2.864 7、2.507 5,介孔孔隙结构复杂程度相对较低;3)有机质丰度有利于A岩、B岩和C岩宏孔孔隙结构的发育,会导致C岩介孔和D岩孔容、比表面积减小;有机质演化程度对A岩介孔、B岩和C岩介孔起到建设作用,对C岩宏孔、D岩介-宏孔有破坏做用;4)脆性矿物含量越高C岩介孔和D岩孔容比表面积越大,而A岩、B岩宏孔、C岩宏孔孔容、比表面积减小;黏土矿物对A岩介孔、C岩介孔及D岩的孔隙系统发育起到建设作用,对B岩宏孔和C岩宏孔有破坏作用。孔隙结构的发育主要受有机质(有机质丰度、有机质演化程度)和矿物组份(脆性矿物含量、黏土矿物含量)的影响,不同岩性、不同尺度的孔隙发育影响因素各有差异。

纳米C-S-H-PCE对免蒸养高强混凝土性能的影响

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建筑外墙保温饰面板的环温辐射解耦测试方法

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