温度对管线钢H2S/CO2腐蚀行为的影响

利用高温高压反应釜模拟高含硫气田H2S/CO2共存环境,在流动溶液介质中进行腐蚀实验,辅以SEM和XRD,探讨了温度对API-X60管线钢H2S/CO2腐蚀行为的影响.结果表明:随温度的升高X60钢的腐蚀速率先升高后降低,腐蚀形态由局部腐蚀趋于全面腐蚀,高温区有点蚀倾向.低温区形成的腐蚀产物以马基诺矿型晶体(FeS1-...     

温度对镍基合金718在高含H_2S/CO_2环境下应力腐蚀行为的影响

镍基合金718是一种高酸性油气井中常用的金属材料,但对其应力腐蚀开裂敏感性及其影响因素的研究较少。利用高温高压反应釜进行应力腐蚀开裂模拟试验,结合扫描电子显微镜(SEM)和能谱仪(EDS)等分析手段研究了温度对718镍基合金在高含H_2S/CO_2环境下应力腐蚀行为的影响。结果表明:在CO_2分压3.5 MPa、H_2S分压3.5 MPa、Cl~-含量150 000 mg/L的模拟环境下,镍基合金718在150,175,205℃下均未发现点蚀和裂纹,应力腐蚀开裂敏感性较低;但随温度升高,镍基合金718的C环应力腐蚀试样表面的钝化膜出现明显的硫化和颗粒状的腐蚀产物,并逐步团聚形成点蚀源。     

H2S／CO2环境中碳钢的腐蚀电化学行为研究

采用电化学测试方法,结合SEM、EDS等分析技术,研究了在H2S／CO2环境中服役和未服役的碳钢弯管的电化学行为。结果表明：在H2S／CO2环境中服役后的弯管耐H2S／CO2腐蚀性能降低。在CO2体系中,电化学阻抗谱由高频容抗弧和低频感抗弧组成,金属表面局部覆盖疏松多孔且保护性差的FeCO3膜。当腐蚀体系中存在H2S时,低频感抗弧消失,金属表面形成均匀致密的FeS膜,可以显著降低弯管的腐蚀速率。     

基于双产品回收的C02驱采伴生气低温分馏工艺

针对某油田CO2驱采伴生气气质特性以及双产品回收指标的要求,运用HYSYS软件数值研究基于CO2-天然气双产品回收的三塔、四塔低温分馏工艺,分析乙烷回收塔塔底温度和原料气中CO2含量对两工艺CO2产品量、添加剂用量、工艺能耗的影响规律,并进行三塔/四塔工艺以及四塔工艺改进前后的对比分析.结果表明:三塔/四塔工艺的C02产量、添加剂用量以及比热耗均随乙烷回收塔塔底温度的升高而增大,比冷耗呈先减后增变化;随着原料气CO2浓度的增大,三塔/四塔工艺的CO2产品量增加,而添加剂用量/比冷耗/比热耗降低;四塔工艺改进后CO2产品量稍有降低,添加剂用量稍有增加,但比冷耗/比热耗平均降低14.4％/30.9％.结论认为,四塔工艺在总能耗、冷/热能耗及添加剂用量上都远低于三塔工艺,且CO2回收率高,改进后的四塔工艺则简化了工艺流程且节能效果更为显著.     

模拟油田H2S/CO2环境中N80钢的腐蚀及影响因素研究

模拟实际含H2S／CO2高温高压井下多相腐蚀环境,研究了不同腐蚀影响因素对N80钢的作用规律。结果表明：在所研究的参数范围内,材料表现出较高的均匀腐蚀速率,且伴有不同程度的局部腐蚀。当其他条件保持相同时,随H2S含量的增加,材料的腐蚀速率先增加后降低;当介质中CO2含量增加时,腐蚀速率则呈单调增大趋势;Ca^2 、Mg^2 的影响与CO2类似,而Cl^-的影响则与H2S具有基本相似的规律。在H2S／CO2混合介质中,N80钢的腐蚀行为受各因素的交互影响,且影响程度不同,各因素作用由大到小依次是：H2S含量、Ca^2 、Mg^2 含量、Cl^-浓度和CO2含量。     

CO2分压对20#钢在CO2/H2O气液两相塞状流中腐蚀行为的影响

利用失重法、SEM、EDS、XRD和 XPS等分析方法在自主设计的动态腐蚀实验装置上研究了 CO2分压对20#钢在CO2/H2O 气液两相塞状流中腐蚀行为的影响,对腐蚀试样进行了腐蚀速率分析、腐蚀形貌特征观察以及腐蚀产物成分与膜层结构特征分析.结果表明:随CO2分压的增加腐蚀速率增加,0.04 MPa、0.28 MPa下分别达到腐蚀速率最小值(1.1609 mm/a)和最大值(1.8988 mm/a);上管壁腐蚀产物随着CO2分压的增加最终形成颗粒较大的节瘤状产物,下管壁腐蚀产物由球形颗粒形成初始致密的单层膜逐渐转变为由致密的内层膜和具有网状连通裂纹的片状疏松外层膜构成;经 EDS元素分析可知上下壁面的腐蚀产物均由Fe、C、O 三种元素构成,XPS分峰图谱显示C 1 s、O 1 s和Fe 2 p均出现了三个拟合峰位,结合XRD分析可知腐蚀产物的主要组成相有 Fe3C、FeCO3、Fe2O3、Fe3O4、FeOOH.     

Characterization of nanosized TiO2 based H2S gas sensor

The present investigation deals with the fabrication of H₂S gas sensor based on semiconducting oxide,TiO₂. Among the various metal oxide additives tested, Al₂O₃ is outstanding in promoting the sensing properties of nanosized TiO₂ based H₂S gas sensor. XRD pattern of TiO₂ /Al₂O₃ shows complete phase formation with anatase structure and grain growth 45 nm. The TiO₂ sensor loaded with 5 wt% Al₂O₃ and 0.5 wt% Pd shows increase in sensitivity to H₂S. The cross sensitivity of 0.5 wt% Pd:5 wt% Al₂O₃ doped TiO₂ also checked for CO, LPG and H₂ gases. The highest sensitivity for low concentration of H₂S was observed using TiO₂ based mixed Al₂O₃ and Pd. The H₂S sensor shows high sensitivity and undesirable cross sensitivity effect using TiO₂/Al₂O₃/Pd as sensing materials.     

基于腐蚀时间效应的含H_2S/CO_2环境中的腐蚀速率预测模型

高含H_2S/CO_2高温高压气井中井筒油管、套管的腐蚀已成为制约井筒完整性的主要因素,一旦井筒完整性失效将会给油气田的开发造成重大影响,并可能导致严重的人员安全、环境及经济损失。由于高温高压H_2S/CO_2环境腐蚀机理较为复杂,国际上使用较为广泛和经典的DE Waard腐蚀速率计算模型已不能预测类似高温高压复杂环境下井筒的腐蚀速率。目前,实验室通常开展短期的腐蚀测试试验,并以此数据预测长期的腐蚀速率,但长期的腐蚀速率与短期腐蚀速率差异甚大。因此,为了准确地预测服役寿命周期内油套管的腐蚀状况,采用自主设计制造的高温高压材料损伤试验平台,模拟气井井筒的实际腐蚀环境,开展CO_2、H_2S腐蚀环境中的电化学腐蚀速率测试试验,研究了不同测试时间下的腐蚀速率,分析了腐蚀速率的时间效应。结果表明:在管柱服役早期,其腐蚀速率较大,随着服役时间的延长,由于形成了腐蚀产物膜以及腐蚀性气体浓度的降低,腐蚀速率逐渐降低直至稳定于某一较低值。最后,利用数理统计方法建立了考虑腐蚀时间效应的腐蚀速率预测模型,可为合理选择油套管材质和油气井的安全评价提供依据。     

模拟下古气藏工况下抗硫油管钢的CO_2/H_2S腐蚀行为

为了更好地理解抗硫油管钢在含硫气田中的腐蚀行为和机理,利用高温高压反应釜装置,结合SEM和XRD分析方法,对N80S和P110S抗硫油钢管在模拟下古气藏环境中CO_2,H_2S共存时的腐蚀行为进行了研究,计算了不同CO_2和H_2S分压比时的腐蚀速率,分析了腐蚀产物特征和成分,探讨了其腐蚀机理。结果表明:2种抗硫油管钢随H_2S含量的增大,腐蚀速率先增大后减小;H_2S微量时抗硫油管钢表面形成了Fe CO3和Fe S等腐蚀物,未见明显的腐蚀坑,随H_2S含量的增大,表面的腐蚀产物为铁的硫化物且存在明显的局部腐蚀。     

含H2S/CO2腐蚀环境下80S和80S-3Cr抗硫油管材料的性能研究

天然气开发生产中常有H2S、CO2共存,引起生产油管严重腐蚀,为了研究H2S/CO2腐蚀环境中不同含硫量对80S和80S-3Cr 2种抗硫油管材料抗腐蚀性能的影响,通过动电位极化扫描和电化学交流阻抗测试研究了2种材料的电化学腐蚀行为.研究结果表明:(1)2种材料的极化曲线均随含硫量增大向X轴负向移动,阴极反应由活化和扩...     

Enhanced H2S gas sensing properties of multiple-networked Pd-doped SnO2-core/ZnO-shell nanorod sensors

Pd-doped SnO₂-core/ZnO-shell nanorods were synthesized by using a three-step process: thermal evaporation of Sn powders in an oxygen atmosphere, atomic layer deposition of ZnO, and Pd diffusion followed by annealing. The sensitivity of the multiple networked SnO₂-core/ZnO-shell nanorod sensor to H₂S gas was found to be improved further significantly by Pd doping. The Pd-doped SnO₂-core/ZnO-shell nanorod sensor showed sensitivities of 6.4, 15.4, and 36.2% at H₂S concentrations of 20, 50, and 100 ppm at room temperature. The sensitivity of the nanorods was improved by more than 10 times at a H₂S concentration of 100 ppm. The sensitivity enhancement of the SnO₂-core/ZnO-shell nanorods by Pd doping may be attributed to the spillover effect, active reaction site generation, and the enhancement of chemisorption and dissociation of gas.     

Effect of thickness on nanostructured SnO2 thin films by spray pyrolysis as highly sensitive H2S gas sensor

Nanostructured SnO2 thin films were prepared by spray pyrolysis technique onto glass substrates with different thickness by varying quantity of precursor solution. The structural, optical and electrical properties of these films have been studied. The crystallographic structure of the films was studied by X-ray diffraction (XRD). It is found that the films are tetragonal with (110) orientation. The grain size increases with thickness. Atomic Force Microscopy (AFM) showed that the nanocrystalline nature of the films with porous nature. The grain size increased 14 to 29 nm with increase in film thickness. The studies on the optical properties show that the direct band gap value decreases from 3.75 to 3.50 eV. The temperature dependence of the electrical conductivity was studied. The activation energies of the films are calculated from the conductance temperature characteristics. The nanostructured SnO2 thin films were used as sensing layers for resistive gas sensors. The dependence of gas sensing properties on the thickness of SnO2 thin films was investigated. The gas response of the SnO2 thin films towards the H2S gas was determined at an operating temperature of 150 degrees C. The sensitivity towards H2S gas is strongly depending on surface morphology of the SnO2 thin films.     

Enhanced catalytic activity of ultrathin CuO islands on SnO/sub 2/ films for fast response H/sub 2/S gas sensors

H/sub 2/S gas-sensing properties of a novel SnO/sub 2/-CuO structure consisting of ultrathin (/spl sim/10 nm) CuO dotted islands (600 /spl mu/m diameter) on 120-nm thick, sputtered SnO/sub 2/ film are compared with a pure SnO/sub 2/ and a SnO/sub 2/-CuO bilayer sensor. The SnO/sub 2/-CuO-dotted sensor exhibited a high sensitivity of 7.3/spl times/10/sup 3/ at a low operating temperature of 150/spl deg/C. A fast response time of 14 s for 20 ppm of H/sub 2/S gas and a recovery time of 118 s under flowing air have been measured. The electronic interaction due to modulation of the space charge regions between the distributed p-type CuO islands on the n-type SnO/sub 2/ thin-film surface and the presence of adsorbed oxygen on the SnO/sub 2/ support have been analyzed. Dissociated hydrogen available from the CuO-H/sub 2/S interaction spills over and its chemical interaction with the adsorbed oxygen on the SnO/sub 2/ surface is found to play a dominant role in the observed fast response characteristics.     

Effect of the gas/product ratio and CO2 concentration on the shelf-life of MA packed fish

Rainbow trout and Baltic herring fillets were gas packed at two different gas/product ratios and two different CO² concentrations. Two reference samples were used; one frozen and one vacuum packed. Changes in gas composition in the gas packages, microbial and sensory quality, K values and drip formation of the fillets were investigated during storage at 2°C. A gas/product ratio of 100 ml/100g gas package was as effective as a vacuum package in preserving the microbial quality of fish and a gas/product ratio of 40ml/100g gas package was as effective as a vacuum package in preserving the sensory quality of fish.     

Development of a detection sensor for lethal H2S gas

The gas which may be lethal to human body with short-term exposure in common industrial fields or workplaces in LAB may paralyze the olfactory sense and impose severe damages to central nervous system and lung. This study is concerned with the gas sensor which allows individuals to avoid the toxic gas that may be generated in the space with residues of organic wastes under 50 degrees C or above. This study investigates response and selectivity of the sensor to hydrogen sulfide gas with operating temperatures and catalysts. The thick-film semiconductor sensor for hydrogen sulfide gas detection was fabricated WO3/SnO2 prepared by sol-gel and precipitation methods. The nanosized SnO2 powder mixed with the various metal oxides (WO3, TiO2, and ZnO) and doped with transition metals (Au, Ru, Pd Ag and In). Particle sizes, specific surface areas and phases of sensor materials were investigated by SEM, BET and XRD analyses. The metal-WO3/SnO2 thick films were prepared by screen-printing method. The measured response to hydrogen sulfide gas is defined as the ratio (Ra/R,) of the resistance of WO3ISnO2 film in air to the resistance of WO3/SnO2 film in a hydrogen sulfide gas. It was shown that the highest response and selectivity of the sensor for hydrogen sulfide by doping with 1 wt% Ru and 10 wt% WO3 to SnO2 at the optimum operating temperature of 200 degrees C.     

Preparation of SiC ultrafine particles from SiH2Cl2 and C2H4 gas mixtures by a CO2 laser

Preparation of SiC ultrafine particles from SiH₂Cl₂-C₂H₄ mixtures by a CO₂ laser was investigated. The powders with specific surface area in the 8–150 m² g^–1 range were obtained by irradiating SiH₂Cl₂-C₂H₄ gas mixtures with a CO₂ laser at atmospheric pressure. X-ray diffraction of the products showed that silicon, SiC and free carbon were produced and the composition of the powders depended on the C₂H₄/SiH₂Cl₂ ratio. The reaction flame temperature changed from less than 1273 K to more than 3073 K with the laser power density and C₂H₄/SiH₂Cl₂ ratio. When SiH₂Cl₂ was irradiated with the CO₂ laser, the reaction temperature was less than 1273 K and silicon particles were formed. When the SiH₂Cl₂-C₂H₄ mixture was irradiated with a CO₂ laser, the reaction temperature was low (<1273 K) at low power density and low C₂H₄/SiH₂Cl₂ ratio, but it increased rapidly to around 3000 K at high laser power density and high C₂H₄/SiH₂Cl₂ ratio (>0.3). SiC was formed at both high and low reaction flame temperatures. It was considered that the rapid increase in the reaction flame temperature was caused by the initiation of exothermic reactions and the increase in laser absorption which was caused mainly by carbon particle formation. Hysteresis was observed between the reaction flame temperature and the power density of the laser beam. It was found that SiH₂Cl₂ underwent a disproportionation reaction on irradiation with the CO₂ laser, and silicon and SiC particles were formed through the various products of the disproportionation reaction. In particular, at low reaction flame temperature, the reactive species, such as SiH₄ and SiH₃Cl, produced by the disproportionation of SiH₂Cl₂ were considered to play an important role in the formation of silicon and SiC particles.     

Importance of H2 gas for growth of hot-wire CVD nanocrystalline 3C-SiC from SiH4/CH4/H2

Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH₄/CH₄/H₂ and the influence of H₂ gas flow rate (F(H₂)) on the film properties was investigated. The SiH₄ gas flow rate was 1 sccm. At the CH₄ gas flow rate (F(CH₄)) of 1 sccm, nanocrystalline cubic SiC (nc-3C-SiC) grew even without H₂. On the other hand, at F(CH₄) = 2 sccm, amorphous SiC grew without H₂ and nc-3C-SiC grew above F(H₂) = 50 sccm. As F(H₂) was increased, the crystallinity improved both at F(CH₄) = 1 and 2 sccm. However, the mean crystallite size decreased at F(CH₄) = 1 sccm and increased at F(CH₄) = 2 sccm. We discuss growth mechanisms of nc-3C-SiC.     

X52钢在H2S/CO2饱和5%NaCl溶液中的腐蚀行为研究

通过动电位扫描、交流阻抗、失重法等试验方法和SEM、EDS、XRD等表面分析技术对APIX52钢在35℃的H2S/CO2饱和5%Nacl溶液中的腐蚀行为进行了研究.结果表明,在本试验条件下,APIX52钢以H2S腐蚀为主,随着时间的延长,X52钢的腐蚀速率逐渐减小,最后趋于一稳定值;腐蚀产物膜为双层结构,膜外层较为致密,富含元素Fe和S,膜内层比较疏松,富含元素Fe和O.这种双层结构与腐蚀产物膜的离子选择性有关.