Experimental study of Al agglomeration on solid propellant burning surface and condensed combustion products

Aluminum(Al) particles are commonly added to energetic materials including propellants,explosives and pyrotechnics to increase the overall energy density of the composite,but aluminum agglomeration on the combustion surface may lower the combustion efficiency of propellants,resulting in a loss in twophase flow.Therefore,it is necessary to understand the agglomeration mechanism of aluminum particles on the combustion surface.In this paper,a high-pressure sealed combustion chamber is constructed,and high-speed camera is used to capture the whole process of aluminum accumulation,aggregation and agglomeration on the combustion surface,and the secondary agglomeration process near the combustion surface.The microscopic morphology and chemical composition of the condensed combustion products(CCPs) are then studied by using scanning electron microscopy coupled with energy dispersive(SEM-EDS) method.Results show that there are three main types of condensed combustion products:small smoke oxide particles oxidized by aluminum vapor,usually less than 1 μm;typical agglomerates formed by the combustion of aluminum agglomerates;carbonized agglomerates that are widely distributed,usually formed by irregular movements of aluminum agglomerates.The particle size of condensed combustion products is measured by laser particle size meter.As the pressure increases from 0.5 MPa to 1.0 MPa in nitrogen,the mass average particle size of aluminum agglomerates decreases by 49.7%.As the ambient gas is changed from 0.5 MPa nitrogen to 0.5 MPa air,the mass average particle size of aluminum agglomerates decreases by 67.3%.Results show that as the ambient pressure increases,the higher oxygen content can improve combustion efficiency and reduce the average agglomeration size of aluminum particles.

Experimental study on solid particle migration and production behaviors during marine natural gas hydrate dissociation by depressurization

Sand production is one of the main obstacles restricting gas extraction efficiency and safety from marine natural gas hydrate(NGH)reservoirs.Particle migration within the NGH reservoir dominates sand production behaviors,while their relationships were rarely reported,severely constrains quantitative evaluation of sand production risks.This paper reports the optical observations of solid particle migration and production from micrometer to mesoscopic scales conditioned to gravel packing during depressurization-induced NGH dissociation for the first time.Theoretical evolutionary modes of sand migration are established based on experimental observations,and its implications on field NGH are comprehensively discussed.Five particle migration regimes of local borehole failure,continuous collapse,wormhole expansion,extensive slow deformation,and pore-wall fluidization are proved to occur during depressurization.The types of particle migration regimes and their transmission modes during depressurization are predominantly determined by initial hydrate saturation.In contrast,the depressurization mainly dominates the transmission rate of the particle migration regimes.Furthermore,both the cumulative mass and the medium grain size of the produced sand decrease linearly with increasing initial methane hydrate(MH)saturation.Discontinuous gas bubble emission,expansion,and explosion during MH dissociation delay sand migration into the wellbore.At the same time,continuous water flow is a requirement for sand production during hydrate dissociation by depressurization.The experiments enlighten us that a constitutive model that can illustrate visible particle migration regimes and their transmission modes is urgently needed to bridge numerical simulation and field applications.Optimizing wellbore layout positions or special reservoir treatment shall be important for mitigating sand production tendency during NGH exploitation.

Highly efficient and selective photocatalytic dehydrogenation of benzyl alcohol for simultaneous hydrogen and benzaldehyde production over Ni-decorated Zn_(0.5)Cd_(0.5)S solid solution

Photocatalytic conversion of solar energy into hydrogen and high value-added fine chemicals has attracted increasing attention. Herein, we demonstrate an efficient photocatalytic system for simultaneous hydrogen evolution and benzaldehyde production by dehydrogenation of benzyl alcohol over Nidecorated Zn_(0.5)Cd_(0.5)S solid solution under visible light. The photocatalytic system shows an excellent hydrogen production rate of 666.3 μmol h^(-1) with high stability. The optimal apparent quantum yield of52.5% is obtained at 420 nm. This noble-metal-free photocatalytic system displays much higher activity than pure Zn_(0.5)Cd_(0.5)S and Pt-loaded Zn_(0.5)Cd_(0.5)S solid solution. Further studies reveal that the metallic Ni nanocrystals play an important role in accelerating the separation of photogenerated charge carriers and the subsequent cleavage of α-C–H bond during dehydrogenation of benzyl alcohol.

Simulation of biodiesel industrial production via solid base catalyst in a fixed-bed reactor

Biodiesel industrial production based on a solid base catalyst in a fixed-bed was simulated. The lab and bench scale experiments were carded out effectively, in which the kinetic model is established and it can describe the transesterification reaction well. The Antoine equation of biodiesel is regressed with the vapor-liquid data cited of literature. The non-random two liquid （NRTL） model is applied to describe the system of fatty acid methyl ester （FAME）, methanol and glycerol and parameters are obtained. The Ternary phase map is obtained from Aspen Plus via the liquid-liquid equilibrium （LLE） data. In order to describe the production in a fixed-bed performs in industrial scale after being magnified 1 000 times, the Aspen Plus simulation is employed, where two flowsheets are simulated to predict material and energy consumption. The simulation results prove that at least 350. 42 kW energy consumption can be reduced per hour to produce per ton biodiesel compared with data reported in previous references.

Influence of Polyepoxysuccinic Acid on Solid Phase Products in Portland Cement Pastes

The influence of polyepoxysuccinic acid（PESA）on the solid phase products in hydrated Portland cement pastes was investigated by isothermal calorimetry,X-ray diffraction（XRD）,^29Si and ^27Al nuclear magnetic resonance（NMR）.The results indicated that PESA bonds Ca^2＋ions in pore solution to prevent portlandite formation,and also combines with Ca^2＋ions on the surface of silicate minerals to prolong the control time of phase boundary reaction process,leading to the retardation of silicate mineral hydration.Meanwhile,the interlayer Ca^2＋ions in Jennite-like structure bridging PESA and C-S-H gels prevent silicate tetrahedron and aluminum tetrahedron from occupying the sites of bridging silicate tetrahedron,which causes the main existence of dimer in C-S-H structure,deceases the degree of Al^3＋substituting for Si^4＋and promotes the transformation from 4-coordination aluminum to 6-coordination aluminum.Furthermore,the-Ca^＋chelating group from reacting PESA with Ca^2＋ions combines easily with SO4^2-ions,resulting in transformation from ettringite,AFm to TAH（Third aluminum hydrate）.However,with the higher addition of PESA,it will bridge the excess PESA by Ca^2＋ions to form a new chelate with ladder-shaped double chains structure,which not only reduces the amount of PESA bonding Ca^2＋ions,but also decreases its solidifying capability for SO4^2-ions,leading to the transformation from TAH to AFm or ettringite.Meanwhile,at later hydration,the inhibition effect of PESA on cement hydration is weakened,and the transformation degree from TAH to AFm is higher than that to AFt with the addition of PESA.

Failure criterion effect on solid production prediction and selection of completion solution

Production of fines together with reservoir fluid is called solid production. It varies from a few grams or less per ton of reservoir fluid posing only minor problems, to catastrophic amount possibly leading to erosion and complete filling of the borehole. This paper assesses solid production potential in a carbonate gas reservoir located in the south of Iran. Petrophysical logs obtained from the vertical well were employed to construct mechanical earth model. Then, two failure criteria, i.e. Mohre Coulomb and Mogi-Coulomb,were used to investigate the potential of solid production of the well in the initial and depleted conditions of the reservoir. Using these two criteria, we estimated critical collapse pressure and compared them to the reservoir pressure. Solid production occurs if collapse pressure is greater than pore pressure. Results indicate that the two failure criteria show different estimations of solid production potential of the studied reservoir. Mohre Coulomb failure criterion estimated solid production in both initial and depleted conditions, where Mogi-Coulomb criterion predicted no solid production in the initial condition of reservoir. Based on Mogi-Coulomb criterion, the well may not require completion solutions like perforated liner, until at least 60% of reservoir pressure was depleted which leads to decrease in operation cost and time.

Application of Solid Thinking Evolve in Product Modeling Design

In view of application characteristics of Solid Thinking Evolve in product modeling design, and the practical design of cosmetics packaging, this paper introduced the unique Construction TreeTM, fast, convenient and easy features of Solid Thinking Evolve, and its application prospects in product development.

Lateral bearing characteristics of subsea wellhead assembly in the hydrate trial production engineering

Conductor and suction anchor are the key equipment providing bearing capacity in the field of deep-water drilling or offshore engineering,which have the advantages of high operation efficiency and short construction period.In order to drill a horizontal well in the shallow hydrate reservoir in the deep water,the suction anchor wellhead assembly is employed to undertake the main vertical bearing capacity in the second round of hydrate trial production project,so as to reduce the conductor running depth and heighten the kick-off point position.However,the deformation law of the deep-water suction anchor wellhead assembly under the moving load of the riser is not clear,and it is necessary to understand the lateral bearing characteristics to guide the design of its structural scheme.Based on 3D solid finite element method,the solid finite element model of the suction anchor wellhead assembly is established.In the model,the seabed soil is divided into seven layers,the contact between the wellhead assembly and the soil is simulated,and the vertical load and bending moment are applied to the wellhead node to simulate the riser movement when working in the deep water.The lateral bearing stability of conventional wellhead assembly and suction anchor wellhead assembly under the influence of wellhead load is discussed.The analysis results show that the bending moment is the main factor affecting the lateral deformation of the wellhead string;the anti-bending performance from increasing the outer conductor diameter is better than that from increasing the conductor wall thickness;for the subsea wellhead,the suction anchor obviously improves the lateral bearing capacity and reduces the lateral deformation.The conduct of the suction anchor wellhead assembly still needs to be lowered to a certain depth that below the maximum disturbed depth to ensure the lateral bearing stability,Thus,a method for the minimum conductor running depth for the suction anchor wellhead assembly is developed.The field implementations show that compared with the first round of hydrate trial production project,the conductor running depth is increased by 9.42 m,and there is no risk of wellhead overturning during the trial production.The method for determining the minimum conductor running depth in this paper is feasible and will still play an important role in the subsequent hydrate exploration and development.

生防枯草芽孢杆菌Czk1固体发酵工艺条件优化

枯草芽孢杆菌(Bacillus subtilis)Czk1是一株具广谱拮抗、促生和诱导植株产生抗病性的根际益生菌。为了全面资源化利用农业废弃物中的有机养分和促进对植物土传病害的生物防治,本研究以Czk1为研究对象,以鸡粪为底肥,分别利用玉米秸秆、菌糠、椰糠堆肥为原料,采用液固两相发酵工艺,以稀释平板菌落计数法测定活菌总数和芽孢数,经过单因素和正交试验方法,明确Czk1固体发酵物料的配方、工艺参数和培养条件。得出Czk1固体发酵的最优条件:最佳原料为菌糠鸡粪堆肥,Czk1接种重量为10%,黄豆粉添加量为10%,含水量为40%,发酵温度为37℃,翻抛1次/72h,在此条件下,Czk1菌株中的芽孢活菌数量总量可以达到8.63×10^(8)CFU/g,芽孢数为8.37×10^(8)CFU/g。其次,发酵效果较佳的原料为秸秆鸡粪堆肥,Czk1接种量为10%,添加5%黄豆粉,40%含水量,发酵温度为37℃,翻抛1次/72 h,此条件下,Czk1接种菌株中的活菌数量总量可达到6.53×10^(8)CFU/g,芽孢数为5.97×10^(8)CFU/g;另外,在此配方条件下再添加30%菌糠,Czk1菌株的活菌数量总量及芽孢数分别可达到8.70×10^(8)CFU/g和6.90×10^(8)CFU/g。4种发酵生物肥原料的理化性质测定表明,其有机质含量、碳氮比均有较大差异,其中以鸡粪为原料其pH、全磷和全钾含量均最高,碳氮比最低,氮、磷、钾总含量均高于秸秆、椰糠和菌糠;秸秆为原料其电导率、有机质含量最高;椰糠为原料其全氮含量最高,菌糠为原料碳氮比最高。不同鸡粪与菌糠、秸秆及椰糠组合的生物有机肥的种子发芽指数均大于80%。因此,枯草芽孢杆菌Czk1具有良好的开发利用价值,选择合适的发酵生产条件可将农业废弃物制备出高质量的生物有机肥。

固体氧化物电解槽辅助煤电机组深度调峰技术可行性研究

常规的煤电机组灵活性改造方案,难以消除频繁快速变负荷对热力系统造成的潜在寿命折损与设备安全风险。为提高煤电机组参与深度调峰的长期安全性与经济性,以某国产超超临界二次再热1000 MW燃煤机组为应用对象,提出了基于氢储能系统的煤电机组“健康调峰”技术路线,并论证了调峰煤电制氢的间接碳减排意义。在此基础上,分析比较了不同制氢工艺与煤电厂生产条件的匹配程度,认为固体氧化物电解槽(SOEC)制氢为综合最优方案,据此给出了SOEC耦合煤电调峰的原理性设计方案,最后以年度负荷曲线对新方案进行了财务分析。计算结果表明,示例机组自第6年起每年可获得1.07亿元/年的净利润,每年减少碳排放281.92 t,同时获得设备延寿、降耗减碳等其他收益。相关结论对于指导调峰煤电机组的健康安全运行具有参考意义。

PRiME HLB前处理技术联合超高效液相色谱-三重四极杆质谱系统检测水产品中17种磺胺类药物残留

使用通过型固相萃取小柱PRi ME HLB处理水产品样品,建立了一种水产品中17种磺胺类药物的简单、快速的筛选分析方法。水产品样品经80%乙腈水溶液(含0.2%甲酸)提取,过PRi ME HLB固相萃取柱净化,浓缩后经C_(18)色谱柱梯度洗脱分离,超高效液相色谱-三重四极杆质谱系统进行定量分析。结果表明,17种磺胺类药物在1.0~50.0 ng·mL^(-1)线性关系良好,相关系数R^(2)>0.99;该方法检出限为2μg·kg^(-1);添加浓度为10μg·kg^(-1)时方法回收率在71.3%~118.4%,RSD值均小于20%。

煤层气储层气-液-固多相渗流规律研究

揭示储层非饱和流阶段煤粉运移产出规律,对煤层气高效排采具有重要现实意义。基于气-液-固三相流模拟装置,通过设定不同煤粉粒径、注入流速、裂缝宽度和煤粉质量分数等条件,开展了煤层气储层非饱和流阶段煤粉产出运移特征试验,并分析了煤粉沉淀量、产出量及煤岩气相与液相渗透率变化特征。研究表明:随着裂缝宽度增加,煤粉产出量呈现出逐渐增大的趋势,沉淀量呈现出先增大后减小的变化特征,在裂缝宽度为0.1 mm时达到最大值;随着煤粉质量分数的增大,产出量表现为先增大后减小(峰值点在0.15‰附近),沉淀量逐渐增大,说明煤粉在储层中运移存在一定的单位体积含量极值,超过极值后,煤粉将大量沉淀并堵塞孔裂隙;合理控制煤层气产水产气速率,能够有效地控制煤粉的产出,煤粉沉淀量和产出量随着注入流速的增长均呈现出先增大后减小的趋势,注入流速为5.0 mL/min时的煤粉沉积量最大,在流速为7.5 mL/min时煤粉产出量相对较高;液相渗透率演化特征呈现出逐渐降低和先稳定后逐渐降低2种变化趋势,气相渗透率演化特征较为复杂;综合注入压力、煤岩渗透率变化、煤粉产出和沉淀特征,可将煤粉在裂缝中运移划分为缓慢沉积、快速沉积和完全堵塞3个阶段。

固相萃取-高效液相色谱法同时测定水产品中15种磺胺类药物残留

建立固相萃取-高效液相色谱法(solid phase extraction-high performance liquid chromatography,SPE-HPLC)同时检测水产品中15种磺胺类药物(sulfonamides,SAs)残留。样品用乙酸乙酯提取,正己烷脱脂,PCX(polymer cation exchange)固相萃取柱净化,采用高效液相色谱法检测,色谱条件为:Waters C18(4.6 mm×250 mm,5.0μm)色谱柱分离,以甲醇和含体积分数1.1%乙酸的PBS缓冲液(0.01 mol/L)为流动相进行梯度洗脱,检测波长为270 nm。15种SAs在65 min内达到完全分离,在0.5~10.0μg/m L时线性关系良好,相关系数均大于0.9900;方法检出限为10~20μg/kg,定量限为20~60μg/kg;对空白鱼肉样品进行了3个质量分数水平(500、1000、2000μg/kg)的加标实验,测定其空白加标回收率为73.1%~109.6%,相对标准偏差(relative standard deviations,RSDs)在1.0%~6.7%。实验建立的检测方法重现性和稳定性好、检出限低。对江西10个不同品种的水产品中磺胺类药物残留进行了采样检测,结果均未检出,表明江西水产品中磺胺类药物残留情况并不严重。

有机固废资源化制氢研究进展

重点介绍了当前有机固废资源化制氢的研究现状和技术原理,包括生物处理和热化学处理2种主要技术途径;总结了各种技术的优缺点以及在实际工程中面临的挑战,并展望了未来的研究方向,为有机固废资源化制氢研究提供重要参考。

面向智能制造的实木家具产品数字化设计技术

在智能制造技术的推动下,传统家具制造业迈上了数字化转型的道路。相较于已发展完善工业4.0设计生产一体化的板式家具,实木家具因其缺乏标准化、信息化程度低等因素,数字化转型亟待寻求发展路径。设计是设计生产一体化定制流程的第一环节,是流程的数据源头,因而设计阶段的技术突破是传统实木家具企业实现数字化转型的首要步骤,数字化设计技术是实木家具企业数字化转型的关键技术。在总结我国实木家具设计生产一体化现状的基础上,分析实木家具发展数字化转型亟待解决的难点问题,即改善实木家具设计模式、规范产品体系、提高零部件标准化、建立完善产品数据库和生产工艺数据库。以实木家具产品设计为切入点,分析数字化软件在一体化发展中的应用,基于传统家具企业数字化转型升级路径,构建了实木家具数字化设计实施技术路径,具体包括:数字化模型构建(产品成组和零部件标准化、信息数据模型构建)、产品数据库构建、系统数据对接、基于数字化设计平台的大规模定制等,旨在为我国实木家具的数字化转型升级提供一定的参考。

纳米气泡的特性及其在有机固体废物厌氧消化中的应用

基于国内外研究现状,分析了纳米气泡(NBs)的基本性质和产生方式,以及改善厌氧消化性能的作用机理,综述了NBs在有机固体废物厌氧消化中的研究进展,以及在增强厌氧消化稳定性、加快水解速率、提高甲烷产量等3个方面的应用,提出了加强不同气体NBs理化性质研究、开发多种气源、提升检测能力、降低能耗和成本等后续研究展望。

基于新能源消纳的高温电解制氢系统建模与控制方法研究

基于新能源随机波动以及低温电解制氢系统转化效率较低且无法切换到发电状态,提出一种高温电解制氢变负载情形下的高效最大产氢点多模型优化控制方法。首先构建计及辅助设备在内的高温固体氧化物电解系统整体协同运行的多能耦合优化模型,分析其影响系统电解的工作温度、电流强度、物料流速等诸多因素并导出高能安全产氢率;其次,在PID控制的基础上,给出一种既能实现变负荷同步准确跟踪产氢轨迹和优化电网调控需求,又能最大优化产氢效率的自适应时变线性变参数模型预测控制方法;最后,通过算例仿真验证所提方法较PID控制电解系统升温速率快,过渡时间短,电解电流、水蒸气流速、H2流速、电炉功率都能平稳过渡至稳态点,具有一定的理论和实用价值。

固体氧化物电解池的发展及研究现状

固体氧化物电解池(SOEC)可以高效、清洁地与可再生能源进行耦合并将其转化为化学能,是一种高效、环保的能量转化装置,但是存在长期运行性能衰减问题,这个问题也是固体氧化物电解水制氢实现大规模商业化的关键所在。本文简要介绍了SOEC的发展历程、类别及其组成和运行原理;详细阐述了该项技术的优、缺点及运行成本;重点对SOEC性能衰减的因素进行了分析,SOEC的组成、运行模式、连接板材料及运行条件等是造成性能衰减的主要因素;最后通过论文和专利数量分析了固体氧化物电解池的研究现状和未来发展趋势,认为虽然固体氧化物燃料电池(SOFC)发展较为成熟,但迫于目前环境需求,为了充分利用清洁能源,降低碳排放,SOEC制氢技术的大规模商业化必然是未来行业的发展方向,目前SOEC性能的稳定及低成本制备是该技术发展面临的主要问题。

一株硫酸盐还原菌脱硫固铀性能及其固铀稳定性研究

从某铀矿山周边土壤中富集分离出一株硫酸盐还原菌A1_(S)XC21Q,研究了该菌株在不同pH、温度、SO_(4)^(2-)浓度下的脱硫和固铀性能,及其固铀产物的稳定性。结果表明:pH升高有利于该菌对SO_(4)^(2-)和铀的去除,初始pH为5.5~7.0条件下,SO_(4)^(2-)和铀的去除率均可达到95%以上;初始SO_(4)^(2-)浓度增加会降低菌株对SO_(4)^(2-)和铀的去除率,但在SO_(4)^(2-)浓度为2000 mg/L条件下,SO_(4)^(2-)和铀的去除率仍可达到75.42%和50.57%;温度升高可显著加速SO_(4)^(2-)和铀的去除,25~35℃条件下,SO_(4)^(2-)和铀的去除率均达到95%左右;A1 S XC21Q菌株可将富集于其表面的铀转移到细胞内部并形成多个“核状”磷酸铀酰络合物,形成的固铀产物稳定。从A1 S XC21Q菌脱硫固铀效果及其固铀产物稳定性来看,该菌有望用于后续酸法地浸铀矿山退役采区地下水生物修复技术试验研究中。

固体火箭发动机中最终凝相产物特性分析

铝颗粒的加入可以有效提高固体推进剂的能量特性,但也带来了两相流比冲损失、熔渣沉积和喷管烧蚀加剧等消极影响,因此,对固体火箭发动机最终凝相产物特性展开研究对评估和提升固体火箭发动机性能具有重要意义。以燃烧终产物为主要研究对象,搭建了基于粒度分析仪的高温高速颗粒特性动态测量系统,对AP/HTPB含铝复合推进剂开展了高温高压下固体火箭发动机试验研究,获得了排气羽流中燃烧终产物分布特性,包括燃烧终产物粒径、均值粒径及颗粒种类等随时间的变化规律,为全面了解凝相产物粒度分布特性提供试验和数据支撑。根据发动机燃烧室压力分布趋势,将固体火箭发动机的工作过程划分为3个阶段(阶段①~③),研究表明:阶段①排气羽流中固体颗粒包括黑火药和推进剂两种燃烧产物,黑火药的随机燃烧特性、燃烧室压力和温度的突升会共同影响该阶段的燃烧终产物分布特性;阶段②燃烧稳定性最高,且该阶段不同时刻燃烧终产物粒径具有较为一致的分布特性,可采用特征模式描述阶段②燃烧终产物的粒径分布;阶段③燃烧终产物粒径分布离散度小于阶段①,该阶段燃烧室压力和温度的突降会影响燃烧终产物分布特性;燃烧室压力和温度突变会改变燃烧终产物模态、峰值粒径及均值粒径等分布特性,不同类型颗粒质量分数随发动机工作阶段的变化而变化。