Prediction of coal structure using particle size characteristics of coalbed methane well cuttings

Severely deformed coal seams barely deliver satisfactory gas production. This research was undertaken to develop a new method to predict the positions of deformed coals for a horizontal CBM well. Firstly, the drilling cuttings of different structure coals were collected from a coal mine and compared. In light of the varying cuttings characteristics for different structure coals, the coal structure of the horizontally drilled coal seam was predicted. And the feasibility of this prediction method was discussed. The result shows that exogenetic fractures have an important influence on the deformation of coal seams. The hardness coefficient of coal decreases with the deformation degree in the order of primary structural, cataclastic and fragmented coal. And the expanding-ratio of gas drainage holes and the average particle size of cuttings increase with the increase of the deformation degree. The particle size distribution of coal cuttings for the three types of coals is distinctive from each other. Based on the particle size distribution of cuttings from X-2 well in a coal seam, six sections of fragmented coal which are unsuitable for perforating are predicted. This method may benefit the optimization of perforation and fracturing of a horizontal CBM well in the study area.

PARTICLE SIZE AND MICROSTRUCTURE OF Ni NANOPOWDERS PREPARED BY ANODIC ARC PLASMA

Pure Ni nanopowders were successfully prepared by the method of anodic arc disch arged plasma with homemade experimental apparatus. The particle size, mircostruc ture and morphology of the particles by this process were characterized via X-ra y powder diffraction (XRD), transmission electron microscopy (TEM) and the corre sponding selected area electron diffraction (SAED); The specific surface area an d pore parameters were investigated by multi-point full analysis of nitrogen ads orption-desorption isotherms at 77K by Brunauer- Emmett-Teller (BET) surface are a analyzer; The chemical composition were determined by X-ray energy dispersive spectrometry (XEDS) equipped in SEM and element analyze instrument. The experime nt results indicate that the samples by this method with high purity,the crystal structure of the particles is as same as the bulk material, is fcc structure, w ith average particle sizes about 47nm, ranging from 20 to 70nm, and distributed uniformly in spherical chain shapes, the specific surface areavis 14.23m2/g, po re volume of pore is 0.09cm3/g and average pore diameter is 23nm.

Structure and properties of forming adsorbents prepared from different particle sizes of coal fly ash

In this paper, different particle sizes of coal fly ash FA-R(D50= 15.75 μm), FA-A(D50= 3.61 μm) and FA-B(D50= 1.73 μm) were treated with Na OH solution to prepare the forming adsorbents FFA-R, FFA-A and FFA-B.The structure and adsorption properties of the forming adsorbents for methylene blue(MB) from aqueous solution were examined. The results showed that the specific surface areas and adsorption capacities of the forming adsorbent for MB increased with decreasing particle size of raw coal fly ashes. The adsorption kinetic data of MB on FFA-R, FFA-A and FFA-B fitted the second-order kinetic model very well with the rate constants(k2) of3.15 × 10-2, 3.84 × 10-2and 6.27 × 10-2g·mg-1·min-1, respectively. The adsorption process was not only controlled by intra-particle diffusion. The isotherms of MB on FFA-R, FFA-A and FFA-B can be described by the Langmuir isotherm and the Freundlich isotherm, and the adsorption processes were spontaneous and exothermic.

Comparison of Two Methods to Assess the Size Structure of Phytoplankton Community Assemblages, in Liaodong Bay, China

Liaodong Bay is one of the largest semi-enclosed bays located in Bohai Sea,in northeast China.It is an important feeding and spawning place,even wintering and breeding migration base for many marine organisms.The size structure of phytoplankton communities is a key feature of marine ecosystems and can be used as an indicator for algae disaster,but the methods to evalute is still challenging.Here,we compared the size-fractionated chlorophyll-a method with a high-throughout sequencing method in an evaluation of the size structure of phytoplankton assemblages in Liaodong Bay,China,in 2014.The proportion of picophytoplankton was estimated at just 19%according to the results based on size-fractionated chlorophyll-a,which likely represents a severe underestimation.The sequencing method confirmed that many kinds of phytoplankton species appeared in more than one size-fractionated filter membrane,with some even dominating where the filter membrane pore size was greater than the individual phytoplankton size.According to the sequencing method,the phytoplankton assemblages in Liaodong Bay were dominated by picophytoplankton(average proportion=44%),followed by the nanophytoplankton(average 32%),a composition that is more consistent with other studies.The sequencing method provides a more robust way to assess the size structure and taxonomic diversity of marine phytoplankton communities.

Effect of Spherical Particle Size on the Electrochemical Properties of Lithium Iron Phosphate

The effect of spherical particle size on the surface morphology, electrochemical property and processability of lithium iron phosphate was systematically studied. Spherical lithium iron phosphate with different particle size distributions controlled with ball time of precursor slurry was prepared by spray drying method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), charge and discharge measurements and EIS. The electrochemical performances of the sample materials were measured by coin cells and 14500 batteries. XRD shows that the spherical lithium iron phosphate with different particle sizes all have good crystal structure due to the perfect mixing of the raw materials and rapid drying. The lithium iron phosphate microsphere with different particle sizes self-assembled with submicron primary particles has a core-shell structure. The longer ball time the precursors are, the smaller the active material particles are prepared. The electrode material with 6 h ball time of precursor slurry has the best physical properties and the processability. The composite has a uniform particle size and higher tap density of 1.46 g/cm3, which delivers a discharge capacity of 167.6 mAh/g at a discharge rate of 0.5 C. The results were confirmed by the 14 500 mA h cylindrical batteries, which delivers a discharge capacity of 579 mAh at 0.5 C. And low-temperature performance with capacity of 458.5 mA h at -20 °C under a discharge rate of 0.5 C is the 79.2% of the same discharge rate at 25 °C. Otherwise, the 14500 batteries also exhibit excellent cycling performance and the capacity maintains 93% after 2 000 cycles.

Preparation and particle size characterization of Cu nanoparticles prepared by anodic arc plasma

Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2/g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

Effects of particle size and content of RDX on burning stability of RDXbased propellants

Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. However, these effects and the corresponding mechanisms are still controversial. In this work, we investigated the physicochemical processes during burning and the corresponding mechanisms through the technologies of structure compactness analysis on the base of voidage measurement and theoretical interfacial area estimation, apparent burning rate measurement using closed vessel(CV)and extinguished burning surface characterization relying on interrupted closed vessel(ICV) and scanning electron microscope(SEM). The results indicate that the voidage increased with the increase of RDX content and particle size due to the increasing interfacial area and increasing interface gap size,respectively. The apparent burning rate increased with the increase of RDX particle size because of the decreasing RDX specific surface area on the burning surface, which could decrease the heat absorbing rates of the melting and evaporation processes of RDX in the condensed phase. Similarly, the apparent burning rate decreased with the increase of RDX content at pressures lower than around 55 MPa due to the increasing RDX specific surface area. Whereas, an opposite trend could be observed at pressures higher than around 55 MPa, which was attributed to the increasing heat feedback from the gas phase as the result of the increasing propellant energy. For propellants containing very coarse RDX particles, such as 97.8 and 199.4 μm average size, the apparent burning rate increased stably with a flat extinguished surface at pressures lower than around 30 MPa, while increased sharply above around 30 MPa with the extinguished surface becoming more and more rugged as the pressure increased. In addition, the turning degree of u-p curve increased with the increase of coarse RDX content and particle size, and could be reduced by improving the structure compactness.

Creating burdock polysaccharide-oleanolic acid-ursolic acid nanoparticles to deliver enhanced anti-inflammatory effects:fabrication,structural characterization and property evaluation

This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.

Occurrence and influence of residual gas released by crush methods on pore structure in Longmaxi shale in Yangtze Plate, Southern China

The composition of gas released under vacuum by crushing from the gas shale of Longmaxi Formation in Upper Yangtze Plate,Southern China was systematically investigated in this study.The effect of residual gas release on pore structures was checked using low-pressure nitrogen adsorption techniques.The influence of particle size on the determination of pore structure characteristics was considered.Using the Frenkel-Halsey-Hill method from low-pressure nitrogen adsorption data,the fractal dimensions were identified at relative pressures of 0‒0.5 and 0.5‒1 as D1 and D2,respectively,and the evolution of fractal features related to gas release was also discussed.The results showed that a variety component of residual gas was released from all shale samples,containing hydrocarbon gas of CH4(29.58%‒92.53%),C2H6(0.97%‒2.89%),C3H8(0.01%‒0.65%),and also some non-hydrocarbon gas such as CO2(3.54%‒67.09%)and N2(1.88%‒8.07%).The total yield of residual gas was in a range from 6.1μL/g to 17.0μL/g related to rock weight.The geochemical and mineralogical analysis suggested that the residual gas yield was positively correlated with quartz(R^2=0.5480)content.The residual gas released shale sample has a higher surface area of 17.20‒25.03 m^2/g and the nitrogen adsorption capacity in a range of 27.32‒40.86 ml/g that is relatively higher than the original samples(with 9.22‒16.30 m^2/g and 10.84‒17.55 ml/g).Clearer hysteresis loop was observed for the original shale sample in nitrogen adsorption-desorption isotherms than residual gas released sample.Pore structure analysis showed that the proportions of micro-,meso-and macropores were changed as micropores decreased while meso-and macropores increased.The fractal dimensions D1 were in range from 2.5466 to 2.6117 and D2 from 2.6998 to 2.7119 for the residual gas released shale,which is smaller than the original shale.This factor may indicate that the pore in residual gas released shale was more homogeneous than the original shale.The results indicated that both residual gas and their pore space have few contributions to shale gas production and effective reservoir evaluation.The larger fragments samples of granular rather than powdery smaller than 60 mesh fraction of shale seem to be better for performing effective pore structure analysis to the Longmaxi shale.

Preparation and characterization of colloidal dispersions of graphene-like structures from different ranks of coals

This paper focuses on preparation of colloidal solution of graphene-like structures from different ranks of coals: brown coal,bituminous coal,low-volatile bituminous coal,anthracite. It was found that brown coal thermo-oxidative destruction leads to formation of small d = 32 nm( V = 17%) and large d = 122 nm( V = 11%) fractions of nanoparticles. The thermo-oxidative destruction of bituminous coal leads to formation of nanoparticles d = 50 nm( V = 5.2%) and d = 164 nm( V = 16%). Thermooxidative destruction of low-volatile bituminous coal and anthracite leads to formation of nanoparticles,predominantly,d = 122-190 nm. Carbon nanostructures obtained from coal are negatively charged at pH= 2-12. Colloidal solution of carbon nanostructures at dispersed phase concentration 0. 01 mg/mL is stable for 1 month. Electron diffraction patterns and X-ray analysis of carbon nanostructures showed that nanostructure from brown coal is amorphous and nanostructure from anthracite is crystalline. Results of coal macromolecules modeling and graphene-like structures obtained from them are presented.

Studies on Spinel LiMn_2O_4 Cathode Material Synthesized from Different Mn Sources

The spinel LiMn2O4 cathode material was synthesized with the solid-state reaction method. Four manganese compounds including electrolytic manganese dioxide (EMD), MnCO3, Mn3O4 and nano-EMD were used as Mn sources while LiOH·H2O was used as the uniform Li source. The crystal structure characteristics of these samples produced were investigated by means of XRD, SEM, particle size distribution analysis and specific surface area testing. Their electrochemical properties were also studied by comparing their specific capacity, charge and discharge efficiency and cycle performance.

Influence of particle size on the aggregation behavior of nanoparticles: Role of structural hydration layer

More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and p H all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.

高QI含量中温沥青制备中间相炭微球的研究

以高QI含量的中温沥青(HCTP)为原料,通过热缩聚法制备中间相炭微球(MCMB),考察了反应条件(反应温度、恒温时间和搅拌速率)对MCMB性质的影响。通过偏光显微镜、粒度分析仪、扫描电镜、XRD和拉曼光谱等对MCMB的粒度分布、表面微观形貌和微晶结构进行了研究。结果表明:以HCTP为原料制备MCMB的最佳反应条件为聚合温度430℃、恒温时间4.5 h、搅拌速率120 r/min;在此条件下制备的MCMB球形度好,收率为29.62%,平均粒径为20.87μm,粒度均匀性指数为0.93;1100℃炭化处理后,MCMB的理想石墨化碳微晶质量分数为75.45%。

阻燃水性聚氨酯的制备及对涤纶织物涂层研究

以阻燃聚酯多元醇为磷源对水性聚氨酯阻燃改性,并对改性的阻燃水性聚氨酯乳液、膜及其涂层涤纶织物进行性能表征。结果表明,改性引入的阻燃聚酯多元醇已完全参与了对水性聚氨酯的阻燃改性;当含磷量低于5%时,阻燃水性聚氨酯乳液呈半透明至乳白色,粒径低于100 nm,离心稳定性较好;随着含磷量的增加,阻燃水性聚氨酯膜的吸水率、力学性能及裂解温度有所降低,质量残存率有所上升;含磷量为3%时,其涂层涤纶织物已达到难燃级别;分析认为:利用阻燃水性聚氨酯涂层涤纶织物进行阻燃整理具有可行性。

春季桑沟湾硅藻群落结构对硅酸盐加富的响应研究

2021年5月,在水温13.83~16.96℃下,用现场陆基围隔实验方法研究添加硅酸盐对山东荣成桑沟湾养殖海区浮游植物丰度(以叶绿素a浓度表征)、粒径结构以及群落结构的影响。体积为100 L的直筒型透明聚乙烯袋围隔而成的实验单元,设置3个处理组,每组三个平行:自然海水组1.41μmol/L SiO_(3)-Si(对照组);低浓度组20.00μmol/L SiO_(3)-Si(LS组);高浓度组100.00μmol/L SiO_(3)-Si(HS组);取桑沟湾近岸表层海水70 L,经200μm筛绢过滤后注入实验单元,每个实验单元中均配置2 W的小型抽水泵,保持海水始终处于混匀状态,不与外部水体交换,添加的硅酸盐为分析纯九水硅酸钠,并固定在长200 cm、宽160 cm、高120 cm,容积约3 800 L的陆基围隔中,实验持续时间7 d。结果显示:(1)添加硅酸盐可提高浮游植物叶绿素a浓度,LS组和HS组叶绿素a浓度分别是对照组的1.95倍和1.94倍,主要是小型浮游植物和微型浮游植物的叶绿素a浓度显著提高;(2)硅藻是浮游植物群落结构的优势种,占物种丰富度的77.27%,硅藻细胞丰度变化范围为0.96×103~1.62×103cells/L,LS组和HS组的硅藻细胞丰度比对照组分别增加了53.53%和69.77%;(3)添加硅酸盐显著促进了小环藻(Cyclotella)、小新月菱形藻(Nitzschia closterium f.minutissima)、圆海链藻(Thalassiosira rotula)等生长(P<0.05),其中小新月菱形藻的藻细胞丰度增加显著,比对照组增加了181.69%;(4)添加硅酸盐对浮游植物多样性和均匀度无显著影响,但可显著增加浮游植物群落结构的物种丰富度(P<0.05)。本结果将为后续探索养殖水域关键时段硅元素补充策略、研发浮游植物初级生产力提升技术进而提高贝类养殖容量的可能性提供基础数据和有价值的线索。

东江三角洲河网浮游植物粒径特征研究

于2021-2022年春夏秋冬四个季节对东江三角洲河网的浮游植物叶绿素a浓度及粒径结构(小型Micro,微型Nano,微微型Pico)进行了季节性调查研究。结果显示夏季浮游植物叶绿素a浓度均值明显高于其他季节。粒径组成结果显示,小型和微型浮游植物叶绿素a浓度占比较高,二者浓度占比之和的年平均值为97.25%。粒径结构的季节特征显示,Micro浓度占比季节差异显著,Nano和Pico浓度占比季节差异不显著。空间特征显示,靠近珠江口的站位一般呈现出Nano浓度占比大于Micro浓度占比的规律。冗余分析(Redundancy analysis,RDA)显示,Micro浓度占比与水温、pH和河宽呈正相关关系,Nano浓度占比与透明度呈正相关关系。聚类分析结果显示,调查站位被明显分成了上游和下游两大类群,两大类群间浮游植物粒径组成差异显著,其中两类群中Micro、Nano叶绿素a浓度占比差异显著,Pico叶绿素a浓度占比差异极显著。另外,研究发现,两类群间差异显著的物理因子主要为盐度,差异显著的化学因子主要为pH和TP。结合RDA分析结果,推测盐度和pH是影响东江三角洲浮游植物粒径组成空间分布的关键环境因子。

糙米粉粒径对糙米直条米粉品质的影响

[目的]改善糙米直条米粉品质。[方法]采用低温冲击磨制备平均粒径(D[4,3])分别为370,86,62,47,30μm的糙米粉,并分别制备糙米直条米粉,考察糙米直条米粉淀粉短程有序结构、晶体结构、蒸煮品质和质构特性。[结果]糙米直条米粉淀粉短程有序度和相对结晶度随着粒径的减小呈先升后降的趋势,硬度和咀嚼性也呈先升后降的趋势,由适中粒径(D[4,3]为86μm)糙米粉制作的糙米直条米粉的淀粉短程有序度和相对结晶度最高,硬度和咀嚼性最大,品质最好。[结论]适度粉碎有利于糙米粉中的淀粉在直条米粉制作过程中形成更有序的结构,提高糙米直条米粉的硬度和咀嚼性。

钴基费托合成催化剂影响因素的研究进展

费托合成是将煤、天然气、生物质等碳源转化为燃料和高值化学品的重要手段。钴基催化剂由于具有较高的催化稳定性、较好的抗氧化能力、低水汽转化率以及高液相烃类选择性等被广泛的用于费托合成。为了进一步追求钴基催化剂的高质量比活性,并解析其活性的来源,世界各国研究学者做了大量的研究,采用各种表征手段,解析钴基催化剂的微观结构,并建立构-效关系。本工作分析总结了费托合成反应中钴基催化剂的粒径效应、晶相、载体效应、助剂效应以及特殊空间结构的研究进展,探讨催化剂的微结构与反应活性之间的关联,并对未来发展方向进行了展望。

基于沙粒运动特性的分流对冲式滴头抗堵优化

针对灌溉水源泥沙含量高导致灌水器易堵塞的难题,对分流对冲式滴灌灌水器开展抗堵塞优化研究.通过短周期浑水试验确定出易造成灌水器堵塞的沙粒敏感粒径区间,应用CFD模拟分析流道的流场分布和敏感粒径区间沙粒的运移特性,最后根据数值模拟结果划分出流道边壁中的敏感区域并据此开展结构优化.结果表明:沙粒粒径越大,跟随性越差,造成灌水器堵塞的进程越快,0.10 mm以上的沙粒极易造成灌水器的堵塞.流道边壁上存在敏感区域,沙粒与敏感区域发生碰撞后其运动方向会发生改变并进入旋涡区聚集,导致流道被堵塞的风险显著增加.针对流道边壁敏感区域开展结构优化可显著改善沙粒的运移特性,使沙粒能够顺畅通过灌水器内部的流道单元,优化后灌水器的水力性能降低1.5%,但其抗堵塞性能大幅提高30.0%~60.0%.基于沙粒运动特性提出的结构优化方案可为灌水器流道的抗堵优化设计提供参考.

粒径计算方法对细观混凝土数值建模的影响

采用最小包围盒(MBB)法确定骨料粒径,并与采用等体积球(EVS)法计算的骨料粒径进行比较,分析了这2种粒径计算方法对细观混凝土内部结构的影响.结果表明:采用MBB法计算的骨料粒径与室内试验采用筛分法确定的骨料粒径更为接近;与MBB法相比,EVS法低估了球状、片状和盘状骨料的粒径,且被低估的骨料占比由大到小依次为球状、片状和盘状,EVS法高估了棒状骨料的粒径;粒径计算方法对细观混凝土内部结构的影响因骨料形状类型不同而呈现一定差异性.