Effect of additives on formation of natural gas hydrate

The formation of natural gas hydrate (NGH) is studied in this work. Kinetics data of hydrate formation with no agitation were collected at various concentrations of the aqueous solutions with different additives such as alkylpolyglucside, sodium dodecyl benzene sulfonate and potassium oxalate monohydrate. Various kinds of additive increased the formation rates of NGH and its storage capacity and reduced the induction time of NGH formation. Moreover, the storage capacity, the induction time and the hydrate formation rate were influenced by the concentration of the aqueous solution.     

A kinetic study on medium temperature desulfurization using a natural manganese ore

Natural manganese ores were selected as raw materials for the desulfurization sorbent because of economical efficiency and high reactivity on hydrogen sulfide. Initial reaction rates between H₂S and desulfurization sorbent of natural manganese ores were determined in a temperature range of 400-800°C using a thermobalance reactor. All reactions were first order with respect to H₂S and were expressed by the Arrhenius relation. When the sulfidation reaction was controlled by diffusion, the temperature dependence of the effective diffusivity was given by the Arrhenius equation. Activation energies and frequency factors were obtained from the product layer diffusion coefficient of various sorbents by plotting as an Arrhenius equation form. Several additives were mixed to improve the sulfidation capacity, and NiO was the best additive.     

Natural rubber-based nanocomposites by latex compounding with layered silicates

Natural rubber (NR) based nanocomposites with 10 wt% natural and synthetic layered silicates were produced via the latex compounding method. As layered silicates, sodium bentonite (natural) and sodium fluorohectorite (synthetic) were selected in addition to a non-layered inert filler (English India clay or commercial clay) as reference material. The nanocomposites were prepared by compounding the dispersions of clays and other latex chemicals necessary for vulcanization. The vulcanized nanocomposites were subjected to mechanical, thermal and swelling tests. The silicate dispersion was studied by transmission electron microscopy. Layered silicates outperformed the reference material (commercial clay) in all aspects. This was attributed to the intercalation/exfoliation of the silicates and to the formation of a skeleton ‘(house of cards)’ silicate network in the NR matrix.     

黄河海勃湾水利枢纽对西鄂尔多斯国家级自然保护区胡杨岛的影响分析

海勃湾水利枢纽的建设、运行将对西鄂尔多斯胡杨岛旅游区产生不可逆的影响。经调查分析,胡杨岛胡杨种群分布面积为2.31 hm~2,总株数约为1 800株;胡杨种群表现出增长型特征;胡杨林总生物量为95.43 t。海勃湾水利工程运行后胡杨岛的淹没历时延长,淹没水深、淹没面积显著增加,岛北部低矮位置甚至全年淹没。胡杨部分种子可能落入水中被水流携带,丧失了种子繁殖的条件。根蘖产生的不定芽在4—6月生长期也会浸在水下,不能完成无性繁殖。胡杨幼苗树不高于2.5 m,淹没后无法生存。水库淹没将岛上以陆生生态为主的生态系统演变成以水生生态为主的生态系统,原有的旅游功能将发生变化或丧失,须采取生态补偿措施,减免工程造成的生态影响。     

Experimental and theoretical analysis of the operation of a natural gas cogeneration system using a polymer exchange membrane fuel cell

This paper reports experimental and numerical results of an investigation of five identical cogeneration systems using PEM (Polymer Exchange Membrane) fuel cells and running on natural gas. The natural gas is reformed locally to produce hydrogen. The accuracy of numerical results is validated by comparison with experimental data and the system performances are analysed in terms of electrical, thermal and total efficiencies. It appears that the energetic performances are low, particularly at low current. Simple solutions for enhancing the system electrical performances by modifying control laws are proposed.     

Numerical computation for clustering of carbon particles with various sizes under both natural and magnetizing convections

The behavior of carbon particles from 0.01 to diameters in natural convection flow field of air was numerically studied including the effect of the magnetic field and the Brownian motion. One thousand carbon particles were released randomly in a vertical cylindrical enclosure whose height is equal to its radius. The enclosure was heated from below and cooled from above to produce the bulk flow of the natural convection of air in the atmospheric condition. A coil with electric current was set coaxially at the enclosure bottom to produce a magnetic field. Sample computations are carried out for the enclosure of 3 cm high and maximum magnetic field is 2.8 T or less. The results show that the natural convection of air is enhanced by the magnetic field. With the increase in the magnetic strength, more particles go along the fluid streak lines. With the increase in the particle size, more particles get together at the vortex center and cluster.     

Integrating a membrane and a fluidized pellet reactor for removing hardness: effects of NOM and phosphate

A novel treatment process combining a membrane with outside-in flow configuration and a fluidized pellet rector for removing hardness was studied. The effects of influent water quality, e.g., concentrations of natural organic matter (NOM) and phosphate along with the hydrophobicity of NOM, on the hardness removal efficiency of the novel process were investigated. The hardness removal efficiency decreases with increasing NOM concentration. However, the NOM removal efficiency is independent of NOM concentration and is related to the hydrophobicity of NOM samples. Raw water containing phosphate has adverse impact on the hardness removal efficiency, which decreases from 85% for treating water containing no phosphate to only 38% and 14% for water containing 0.33 mg/L and 1.63 mg/L of phosphate, respectively.     

不同促进剂对NR平衡硫化体系的影响

研究了促进剂的种类，促进剂并用及硫化温度等条件对平衡硫化体系（ＥＣ）硫化天然橡胶（ＮＲ）的影响。结果表明，噻唑类促进剂具有较低的硫化返原率，尤其是促进剂ＤＭ，在１３０～１７０℃的硫化温度范围内，硫化２小时的硫化返原率均为０；当促进剂ＮＯＢＳ或ＣＺ与ＤＭ并用时，可缩短正硫化时间；当ＤＭ摩尔分数分别为４０％和５０％左右时，不仅使硫化２小时的硫化返原率为０，而且可使３００％定伸应力保持恒定；以ＮＯＢＳ或ＣＺ为主促进剂时，正硫化时具有较高的拉伸强度和撕裂强度，但硫化２小时时的降低幅度比ＤＭ大。     

采用主监视窗扩展技术的增强现实三维注册方法

在增强现实三维注册中,采用重新检测策略时顿卡现象严重。提出一种采用主监视窗扩展技术的增强现实三维注册方法。在检测阶段,引入特征点可信度和主监视窗,并设计主监视窗的分割、扩展和调控策略,大幅提升了计算速度;在跟踪阶段,采用基于图像金字塔的光流算法进行特征点跟踪。实验证明,该方法不仅有效缓解了顿卡现象,也提升了系统整体的实时性。     

Adsorption of chromate by surfactant-modified zeolites and MCM-41 molecular sieve

Synthetic and natural zeolites, modified by the quaternary amines, i.e. hexadecyltrimethylammonium (HDTMA) bromide and n-cetylpyridinium bromide (CPB) as well as MCM-41 molecular sieve were employed for removal of chromate from aqueous solution. Obtained data from chromate adsorption experiments over the mentioned materials were compared. It was shown that adsorption data for modified zeolite using the amine was consistent with Langmuir isotherm equation. The maximum chromate adsorption over as synthesized MCM-41 was much greater than that of the natural clinoptilolite and ZSM-5 zeolites.