Procedure for Measuring Low Concentrations of H2 and H2S Above a Water Surface

A simple measuring procedure for low concentrations of H₂ and H₂S (at the level of ppm fractions) above the surface of water by using sensitive gas analyzers is suggested. The procedure is easily accomplished in conditions outside the laboratory (under field conditions).     

Adsorption and decomposition of H2S on Pd(1 1 1) surface: a first-principles study

Gradient-corrected density functional theory was used to investigate the adsorption of H₂S on Pd(1 1 1) surface. Molecular adsorption was found to be stable with H₂S binding preferentially at top sites. In addition, the adsorption of other S moieties (SH and S) was investigated. SH and S were found to be preferentially bind at the bridge and fcc sites, respectively. The reaction pathways and energy profiles for H₂S decomposition giving rise to adsorbed S and H were determined. Both H₂S_(ad) → SH_(ad) + H_(ad) and SH_(ad) → S_(ad) + H_(ad) reactions were found to have low barriers and high exothermicities. This reveals that the decomposition of H₂S on Pd(1 1 1) surface is a facile process.     

Inhibition of sulfide on the simultaneous removal of nitrate and p‐cresol by a denitrifying sludge

BACKGROUND: Many industrial discharges, such as those generated from petrochemical refineries, contain large amounts of sulfurous, nitrogenous and organic contaminants. Denitrification has emerged as a suitable technology for the simultaneous removal of these pollutants in a single reactor unit; however, more evidence is demanded to clarify the limitations of denitrification on the simultaneous removal of sulfide and phenolic contaminants and to optimize the biological process. The aim of this study was to evaluate the capacity of a denitrifying sludge to simultaneously convert sulfide and p‐cresol via denitrification. RESULTS: Sulfide was the preferred electron donor over p‐cresol, imposing a 5 h lag phase (required for complete sulfide removal) on organotrophic denitrification. Addition of sulfide (20 mg S^2? L^?1) to p‐cresol‐amended denitrifying cultures also decreased the reduction rate of nitrate and nitrite, as well as the production rate of nitrogen gas. Nitrite reduction rate was the most affected step by sulfide, decreasing from 35 to 21 mg N (g VSS d)^?1. A synergistic inhibitory effect of nitrate and sulfide was also observed on nitrite reduction. Despite the effects of sulfide on the respiratory rates monitored, complete removal of nitrate, sulfide and p‐cresol could be achieved after 48 h of incubation. CONCLUSION: Our results suggest that simultaneous removal of sulfide and p‐cresol could be achieved in denitrifying reactors, but a large hydraulic residence time may be required to sustain an efficient process due to inhibitory effects of sulfide. Copyright © 2008 Society of Chemical Industry     

Analytical characterization of cadmium cyanamide in CdS thin films and bulk precipitates produced from CBD process in pilot plant

CdS thin films and bulk precipitates were obtained by chemical bath deposition (CBD) in a well-closed reactor. X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, thermal analysis, elemental analysis and leaching have been used to characterize solids and thin films. It has been shown that the proportion of cadmium cyanamide in solids may vary from about 50% to 2% according to physicochemical conditions in solution (time after CBD, ammonia concentration) and that CdO results from CdCN₂ after air annealing of thin films. This last step also increases the crystallinity of the films.     

Shear-induced crystallization of poly(phenylene sulfide)

The crystalline morphology of poly(phenylene sulfide) (PPS) isothermally crystallized from the melt under shear has been observed by polarized optical microscope (POM) equipped with a CSS450 hot-stage. The shish–kebab-like fibrillar crystal structure is formed at a higher shear rate or for a longer shear time, which is ascribed to the tight aggregation of numerous oriented nuclei in the direction of shear. The crystallization induction time of PPS decreases with the shear time, indicating that the shear accelerates the formation of stable crystal nuclei. Under shear, the increase of spherulite growth rate results from highly oriented chains. The melting behavior of shear-induced crystallized PPS performed by differential scanning calorimetry (DSC) shows multiple melting peaks. The lower melting peak corresponds to melting of imperfect crystal, and the degree of crystal perfection decreases as the shear rate increases. The higher melting peak is related to the orientation of molecular chains. These oriented molecular chains form the orientation nuclei which have higher thermal stability than the kebab-like lamellae that are developed later. A new model based on the above observation has been proposed to explain the mechanism of shish–kebab-like fibrillar crystal formation under shear flow.     

���������ɹ���ߺ�����������ѹ�����㷽����MDT���Է���

川东北飞仙关组高含硫气藏气井在完井测试过程中，压力测点位置与产层中部的距离较大，需将压力数据用气柱压力计算公式折算后再进行试井分析解释。文章以质量、动量和能量三大守恒方程和状态方程为基础，考虑了流动气柱的动能损失以及井筒和地层中复杂的传热机理，推导出计算单相气流在井筒不同部位压力和温度的方法。以坡2井为例，应用目前最新的模块化动态地层测试器MDT地层测试技术，对折算的压力进行了验证和对比分析。结果表明，应用文中的压力计算方法，完全可以满足解释的压力数据精度。另外，在没有进行完井测试前利用MDT测压资料确定地层压力等储层参数是较为直接和可靠的方法。同时此法对川东北飞仙关组高含硫气藏的开发动态监测以控制元素硫在井底和井筒的沉积具有十分重要的指导意义。     

激光诱导H_2S催化裂解制备H_2的研究

在室温常压静态条件下研究了以Ｖ２Ｏ５／ＴｉＯ２为催化剂，紫外脉冲激光诱导Ｈ２Ｓ催化分解为Ｈ２和Ｓ的反应及其机理。考察了产氢量与激光不同照射条件之间的关系。     

连续流动分析仪应用于水中硫化物的测定

对连续流动法测定硫化物进行初步探讨和研究。同时与其他几种测定硫化物的方法进行了比较。实验结果表明，连续流动法对硫化物分析在线性、稳定性、最低检测限、准确性和精密度等方面均优于其他方法。     

液化气球罐焊缝H2S应力腐蚀裂纹的返修补焊

对宁夏炼油厂一台200m3低合金钢球罐H2S应力腐蚀裂纹采用气刨打磨后补焊的返修方法表明，碳弧气刨时的骤热不会使裂纹向纵深扩展，只是必须在补焊前将返修部位焊缝两侧各100mm范围内打磨至完全露出金属光泽，以便彻底消除裂纹源，避免补焊时再产生新的微小裂纹。若返修深度不大于罐壁厚度的二分之一，则不必进行射线探伤检查，只须进行100％的超声波检查，在水压试验前后对返修部位进行100％磁粉探伤则是非常必要的。     

利用控制头酸化测试联作的新方法

采用采油树进行酸化作业，安全可靠，但在原钻机试油过程中，采用采油树酸化作业工作量大而繁重，存在一些不便之处。利用控制头替代采油树酸化作业，可以解决困扰酸化施工时来回倒换井口的难题，并且可以缩短试油周期，减少管柱起下钻次数，为含硫化氢油气井的施工提供了安全保障。1997年以来，在塔中26井、塔中126井利用控制头实施酸化作业并获得成功，为酸化测试联作及超深高含硫井的施工积累了实际经验。