天然石英砂中CO_2水合物的分解动力学

The decomposition kinetics for formation of CO2 hydrates in 90 cm3 wet natural silica sands were studied systematically using the depressurization method at the temperatures ranging from 273.2 to 277.2 K and the pressures from 0.5 to 1.0 MPa. The effects of temperature, pressure, particle diameter, porosity, and salinity of formation water on the decomposition kinetics were investigated. The results show that the dissociation percentage increases as temperature increases or as the initial decomposition pressure decreases. An increase in porosity or a decrease in particle diameter of silica sands accelerates the decomposition. Increasing the salinity of the formation water gives rise to a faster decomposition. However, a combination of the present results with the observa-tions in literature reveals that the effect of the coexisting ionic solute depends on its chemical structure.     

β-葡萄糖五乙酸酯的合成

以吡啶为催化剂,利用葡萄糖和乙酸酐的酯化反应合成了β-葡萄糖五乙酸酯,研究了合成的最佳反应条件和粗产品的结晶条件。结果表明最佳条件为：乙酸酐与葡萄糖的物质的量比为1:6,催化剂的用量为葡萄糖质量的20%,反应时间为3 h,结晶溶剂为乙醇,结晶温度为30 ℃,乙醇与粗产品的体积比为2:1;葡萄糖与醋酐的酯化收率达96%,β-葡萄糖五乙酸酯的总收率为75.2%。产品的比旋光度+4～+6°,熔点130～134 ℃,质量分数≥98%（GC）。该方法选择性好、产物收率高。     

三氯乙烯生产废水中氯代烃的脱除

以三氯乙烯生产工业废水为处理对象,采用0价铁催化还原、混凝沉淀法,对氯代烃进行脱除处理,探讨了脱氯处理效果及其反应机理。结果表明,三氯乙烯的脱氯效率大于99％,其他氯代烃脱氯效率大于90％。催化还原反应在常温、常压下进行,反应条件温和,对三氯乙烯生产废水中的氯代烃具有很好的脱除效果。     

利用简化的化学反应动力学模型耦合CFD代码模拟气体燃烧器中的烟黑生成(英文)

A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pressure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the full mechanism using sensitivity analysis, reaction path analysis and quasi steady state (QSS) approximation. The model in premixed flame was validated and with computing savings in diffusion flame was applied by incorporating into a CFD code. Simulations were performed to explore the effect of coflow air on flame structure and soot formation. Thermal radiation was calculated by a discrete-ordinates method, and soot formation was predicted by a simple two-equation soot model. Model results are in good agreement with those from experiment data and detailed mechanism at atmospheric conditions. The soot nucleation, growth, and oxidation by OH are all enhanced by decrease in coflow air velocity. The peak soot volume fraction region appears in the lower annular region between the peak flame temperature and peak acetylene concentration locations, and the high soot oxidation rate due to the OH attack occurs in the middle annular region because of high temperature.     

秸秆固化成型燃料引火助燃剂的点火和烟气排放特性(英文)

Ignition-assisting agents for densified corn stover briquette fuel(DCBF) were developed,and their ignition and emission characteristics were investigated using type LLA-6 household cooking stove.Three waste liquid fuels,waste engine oil(E) ,diesel oil(D) ,and industrial alcohol(A) ,were used as raw materials to make 25 ignitionassisting agents by mixing at different ratios.Their ignition performance was evaluated in terms of ignition time and cost.It was found that ignition-assisting agents ED15(a mix of E and D at volume ratio of 1︰5) and DA51(a mix of D and A at volume ratio of 5︰1) presented better ignition results with shorter ignition time(40-53 s) and lower cost(6.1 and 5.3 cents) at the dosages of 9 ml and 8 ml,respectively.The emission of O2,CO,CO2,NOx,and SO2,the temperature in fume gas,and combustion efficiency were investigated for ED15 and DA51.The results show that the emission of ED15 with the dosage of 9 ml is lower than that of DA51 with the dosage of 8 ml in the ignition process.ED15 at the dosage of 9 ml achieves satisfactory combustion efficiency and emits less pollutant,so it is recommended for practical application.The study will provide a cost-effective and environmentally friendly approach to fast ignite DCBF and break the barrier to the practical application of DCBF.     

雷丸的中性金属蛋白酶的分离纯化、酶学性质及体外驱虫活性

A neutral metalloprotease was purified from the cultured mycelia of Laccocephalum mylittae, an effective medicinal fungus widely used in anthelmintic therapy. The protease was purified to homogeneity with 31.85-fold purification and a final yield of 21.76%. The subunit molecular weight of the protease is about 40000 estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum reaction pH and temperature are 7.5 and 50ºC, respectively. The protease activity is largely enhanced by Ca2+, but highly inhibited by tetrasodium ethylenediaminetetraacetate (EDTA), a metal-chelator, suggesting that the enzyme is a metalloprotease. The Michaelis-Menten constan Km and Vmax value for casein substrate are 6.09 mg&;#8226;ml－1 and 21.32 μg&;#8226;min－1&;#8226;ml－1, respectively. In vitro anthelmintic tests of the protease exhibit distinct lethal effects on the third stage larvae (L3) of Ascaris suum. Scanning electron microscopy and SDS-PAGE analysis indicates that the proteolysis of larvae proteins caused by this protease may relate to the anthelmintic activity of L. mylittae.     

拟塑性流体中伴有聚并的气泡上升混沌特征(英文)

The chaotic characteristics of bubbles rising with accompanying coalescences in pseudoplastic aqueous carboxymethylcellulose sodium (CMC) solution were studied by means of smoothed pseudo Wigner-Ville distribution and Wigner-Hough distribution. The temporal signal of bubble passage was measured utilizing a photoconductive data acquisition system. As bubble coalescence occurred, the smoothed pseudo Wigner-Ville distribution of the signal revealed that the signal could be divided into low-frequency and high-frequency ranges and the transition range according to the distribution feature of frequency domain, which reflected eddy motion of fluid, high frequency fluctuations of fluid velocity and other random components measured in the signal, and bubbles rising accompanied with coalescences, respectively. However, bubble coalescence occurred in the lower position and the frequency range of bubbles motion became wide under higher gas flowrate, while the frequency range of bubbles motion became narrow when the CMC concentration increased. The typical dynamics of bubbles motion, such as periodicity, bifurcation and chaos, could be easily found in terms of the Wigner-Hough distribution.     

曼型气柜检修中密封油泄漏的处理

分析了曼型气柜密封系统在检修过程中出现的密封系统密封油泄漏量大的原因,采取调整滑板活动量、主帆布U型余量、改用弹力较大滑板顶紧弹簧等措施,较好地解决了问题。     

涡-气泡作用模型对搅拌釜中气泡湍流扩散影响的数值研究

Based on trajectory equations of gas bubble, an eddy-bubble interaction (EBI) model was developed. This model considered the effect of non-drag forces and took the eddy-bubble interaction time as the refreshing time scale of turbulent fluctuations. The relationship between the crossing-eddy time and the eddy lifetime was discussed, and the predicted distributions of radial, axial ve-locities of bubbles and gas holdup were also given. Compared with eddy lifetime (EL) model, the EBI model gives somewhat smaller axial velocity in the upper circulation region and larger velocity in the lower circulation region, causing that fewer bubbles reach the lower circulation region and gas holdup becomes higher in the upper circulation region. The predicted gas holdup by the EBI model approaches closer to the experimental data in the discharge stream region.     

乙二胺四乙酸四钠盐缓释微胶囊的制备与表征

The microcapsules with cores of ethylenediamine tetraacetic acid tetrasodium salt (Na4-EDTA) and walls of polyurea were synthesized via an interfacial polycondensation reaction with 2,4-tolylene diisocyanate as an oil-soluble monomer and diethyl triamine as a water-soluble monomer. Various manufacturing parameters, including the amount of emulsifier, agitation speed, stirring time and ratios of the wall materials to core materials, were altered to optimize process variables during the synthesis of microcap-sules, and the effects of these parameters on the characteristics of the microcapsules were examined. The structure, morphology, mean particle size and size distribution were characterized by optical microscope and scanning electron microscopy (SEM), showing that the mean diameter of optimal microspheres was approximately 6 μm, and microcapsules were spherical. In vitro release of Na4-EDTA from these microcapsules was performed in distilled water. Under the optimal preparation conditions, the Na4-EDTA re-lease profiles were biphasic with a burst release followed by a gradual release phase. After an initial burst, a continuous Na4-EDTA release was up to 5-7 days. The optimal synthesis conditions for the microcapsules with stable, good morphology and good con-trolled-release properties were as follows: emulsifier Span-80 10% (by mass), agitation speed 900 r&;#8226;min－1, stirring time 30 min, and the ratio of the wall materials to core materials 0.15.     

水合物降压分解的实验及数值模拟

在天然气水合物一维分解模拟系统上进行模拟多孔介质中水合物降压分解的实验。在考虑天然气水合物分解动力学机理以及流体渗流模型的基础上;建立天然气水合物降压分解的数学模型。利用模型对降压实验进行拟合;获得了多孔介质内水合物分解本征速度常数数量级为10 mol·m^-2·Pa^-1·s^-1;比文献中测定的纯水中水合物分解本征速度常数低3个数量级。对模型进行了参数分析;发现对于实验室规模的一维系统;分解动力学过程控制整个分解过程;而对于现场规模的水合物藏;整个开采过程受水合物藏流动特性的控制;而受水合物分解过程的影响较小。     

天然气水合物形成与生长影响因素综述

天然气水合物(NGH)是水分子和天然气分子形成的一种复杂的笼型晶体,其在油气管道输送、天然气储存和制冷等行业中都具有重要的研究意义和利用价值,但天然气水合物的形成是一个多组分、多阶段的复杂过程,不同因素对于天然气水合物形成和生长的影响尚有待明确。本文介绍了天然气水合物形成的物理过程以及水合物成核的3种机理假说;详细梳理了基质两亲性、添加剂、多孔介质环境和杂质、液体组成、温度压力以及流动条件等因素对于天然气水合物形成和生长的影响,并对其作了简要分析。同时指出,原油组成对于水合物抑制效果的定量化、蜡晶结构对于水合物形成过程中传质和传热的影响以及微观化的动力学抑制剂抑制机理等都是水合物相关研究中需要进一步深入探究和明确的问题。     

天然气水合物生成条件的测定和计算

利用全透明蓝宝石水合物静力学实验装置,测定了4种塔里木油田天然气在纯水中的水合物生成条件.将Chen-Guo 水合物模型应用于天然气水合物生成条件的计算,实验测定的4种天然气水合物生成条件的计算结果和实验结果符合得很好.     

聚乙烯吡咯烷酮在天然气水合物生成中的作用

研究了聚乙烯吡咯烷酮(PVP)在天然气水合物生成中的促进和抑制作用,结果表明PVP作为促进剂时,在确定的反应温度和压力下有一个最佳的浓度,在确定的使用浓度和温度时则有一个最佳反应压力,否则PVP的加入将抑制水合物的生成。认为PVP在低浓度时作为高分子表面活性剂,降低了溶液的表面张力,加速了水合物生成。在高浓度时,其长链上的五元环吸附水合物表面未完成的孔穴,阻止了水合物晶核的增长。     

多孔介质中水合物生成与分解二维实验研究

采用电容、压力、温度测试作为监测手段,自行研制了一套天然气水合物二维开采模拟系统,可用于水合物生成与分解过程中温度场、压力场、分布状态、分解前沿推进速度等动态特性的研究。水合物生成与分解实验表明,温度是影响水合物大量生成的主要因素;重复实验会加长生成时间,往往首次实验所耗总时间最短,说明水的记忆效应并不是对于所有实验系统存在的普遍现象;实验表现出来的特殊的压力变化曲线和规律还表明晶核形成对水合物晶体的生成并非绝对重要。理论分析和实验表明,电容法在测试单相水体相变过程中是有效的,水量是影响电容量变化的关键。在水合物生成过程中,随水合物饱和度的增加、水量的不断减少,电容量总体减小趋势明显。电容测试方法在水合物实验方面有一定的可行性,尤其对于研究多孔介质中水合物生成分解过程中各相的流动特性极有意义,但是要实现在水合物研究方面的有效利用还需要大量的切实的实验验证。     

天然气水合物储运技术中水合物反应器的研究进展

可观的储气率与自保效应的存在使得天然气水合物能作为一种天然气储运的方式,并且在与其他如液化天然气、压缩天然气储运方式比较时有着自己独到的优势。但由于针对水合物储运的研究起步较晚,利用水合物储运天然气的技术尚未成熟。尤其是在水合物反应器的研究上,生成水合物的速率较低,无法达到工业生产所需要的水平。本文通过调研国内外文献与专利等资料,介绍了国内外天然气水合物储运技术发展状况,简述了水合物生成强化的物理化学手段与机械手段,详述了搅拌式等传统天然气水合物反应器与管式、超重力式等新型天然气水合物反应器的结构与工作原理。根据现有水合物反应器的特点与存在的问题,对水合物反应器的研究方向提出建议：未来应当加快对喷淋式、超重力式与流化床式反应器的放大研究,加快针对不同物理强化手段与机械强化手段的协同作用研究,建立起以天然气储运为目的的水合物反应器评价体系。     

水基钻井液中天然气水合物形成的研究进展

依据水基钻井液中天然气水合物生成的相关研究,结合理论与实践,介绍了一些钻井液处理剂对水合物生成的影响,重点概述了水基钻井液对天然气水合物生成的抑制效应,并简要说明了水合物抑制剂在钻井液中应用的相关研究。     

Evaluation on the natural gas hydrate formation process

Gas hydrates have endowed with great potential in gas storage, and rapid formation of gas hydrates is critical to use this novel technology. This work evaluated the natural gas hydrate formation process, which was compared from six parameters, including conversion of water to hydrate, storage capacity, the rate of hydrate formation, space velocity (SV) of hydrate reaction, energy consumption and hydrate removal. The literature was selected by analyzing and comparing these six parameters mentioned above, meanwhile placing emphasis on the three parameters of storage capacity, the rate of hydrate formation and space velocity of hydrate reaction. Through analysis and comparison, four conclusions could be obtained as follows. Firstly, the overall performance of the stirring process and the spraying process were better than other processes after analyzing the six parameters. Secondly, the additive types, the reactor structure and the reactor size had influence on the natural gas hydrate formation process. Thirdly, the energy consumption via reciprocating impact in the hydrate formation process was higher than that via stirring, spraying and static higee. Finally, it was one key for hydrate removal to realize the hydrate industrial production.     

冰-气生成天然气水合物的动力学研究

对由冰生成天然气水合物过程中的过饱和度和过冷度的作用进行了实验研究。结果表明 ,较大的过饱和度和过冷度提高了生成水合物的含气率 ,同时反应还存在一个最佳反应时间。提出冰转化为水合物的过程是一个包括气体的外扩散、产物层内扩散以及界面反应的过程     

冰点以下多孔介质中气体水合物的生成动力学研究进展

青藏高原冻土区储存着大量的天然气水合物资源,CO₂置换开采冻土区的天然气水合物可实现天然气水合物的安全开采和温室气体CO₂的地层封存。冰点以下多孔介质中气体水合物的生成动力学,是冻土区天然气水合物置换开采研究领域的难点和热点问题。本文全面综述了冰点以下多孔介质中气体水合物的生成动力学研究进展,讨论了不同体系冰点以下多孔介质中气体水合物的形成机理及其生成特性;详述了冰生成水合物机理及其冰粉/多孔介质体系中气体水合物的生成特性,分析了冰点以下多孔介质中气体水合物生成动力学研究尚待完善和改进的地方。最后本文指出冰点以下多孔介质中水合物的生成过程是由传热、传质等多种因素所控制,揭示不同过程的主导因素及其影响规律是今后研究的重点方向。目前对冰点以下多孔介质中水合物的生成特性及机理的认识尚未成熟,仍需深入研究。