不同加热温度和降温速率对含蜡原油析蜡点的影响

利用差示扫描量热法(DSC)对原油的析蜡特性进行分析,并得到了析蜡过程的热谱图和dh/d T-T曲线。以大庆原油为研究对象,对dh/d T-T曲线进行分析,探讨了加热理温度、温降速率对析蜡点的影响。结果表明:加热温度高于溶蜡点温度时,析蜡点随温变化小;加热温度低于溶蜡点温度,析蜡点随温度的降低先增大后减小。温降速率越大,析蜡点越低。     

用DSC热分析法研究含蜡原油结蜡特性

利用差示扫描量热法(DSC)对原油的结蜡特性进行分析并得到了结蜡过程的热谱图。分别对大庆管输原油、辽河油田超稠油、辽河油田松山泵站站出口原油进行了DSC热分析法分析。对热谱图进行分析后得到了关于原油的析蜡点、析蜡高峰区温度范围、析蜡热焓、析蜡高峰点、析蜡结束温度等特性参数。通过对三种原油热谱图的比较以及测算得出,大庆管输原油含蜡量最高,而辽河油田超稠油含蜡量极低,胶质,沥青质含量大,所以对于超稠油的运输,应采用降粘的方法对其进行输送。     

费托蜡氧化改性技术研究

本文对费托蜡无催化剂氧化改性技术进行了研究，考察了空气流速、反应温度、反应时间、气体含氧量对氧化蜡酸值、皂化值的影响，分别采用气相色谱法、傅里叶红外光谱法、差式扫描量热法等表征手段对产品性质进行了分析。结果表明，采用无催化剂氧化，不同空气流速、反应温度、反应时间、气体含氧量对费托蜡氧化反应影响显著，通过控制反应工艺条件，可以得到不同酸值、皂化值目标要求的氧化蜡产品。     

近红外漫反射分析技术在测定共聚聚丙烯中乙烯含量的应用

文章探讨了利用近红外漫反射分析技术快速判断共聚聚丙烯中的乙烯含量的应用。用近红外漫反射法收集了样品近红外光谱图。利用中红外方法测定共聚聚丙烯样品的乙烯含量。利用偏最小二乘法线性回归法建立了聚丙烯中聚乙烯含量的近红外光谱预测模型。将近红外法测定结果与中红外方法测定结果进行了比较,对光谱测量的重复性进行了考察。结果表明,利用近红外光谱法与中红外方法的测定结果无显著差异,近红外法具有准确,快速,操作简便和低成本等特点。     

近红外漫反射分析技术在测定聚丙烯粉料中二甲苯可溶物方面的应用

文章探讨了利用近红外分析技术快速判断聚丙烯粉料中的二甲苯可溶物含量的应用。用近红外漫反射法收集了样品的近红外光谱图。参照化学计量学分析方法测定聚丙烯样品的二甲苯可溶物含量。利用偏最小二乘法线性回归法建立了聚丙烯二甲苯可溶物的近红外光谱预测模型。将近红外法测定结果与化学分析方法测定结果进行了比较,对光谱测量的重复性进行了考察。结果表明,利用近红外光谱法与化学分析法的测定结果无显著差异。     

近红外漫反射分析技术在测定低密度聚乙烯密度的应用

利用近红外漫反射分析技术快速判断低密度聚乙烯密度。用漫反射法收集低密度聚乙烯样品的近红外光谱图。利用梯度柱法测定样品密度。用偏最小二乘线性回归法建立预测模型。对两种方法的结果进行比较并考察光谱测量的重复性。结果表明,近红外光谱法与梯度柱法的测定结果无显著差异。     

近红外光谱用于火箭煤油馏程测定的研究

利用近红外光谱法及标准方法对60个火箭煤油样品的馏程进行测定,采用偏最小二乘法建立模型,初馏点与10%馏程的相关系数分别达到0.9299、0.9584。用该模型对10个未知样品进行测定,近红外光谱法预测结果与实测结果相关性很好,其准确度和再现性均符合标准分析方法的要求,表明近红外光谱分析技术代替传统标准方法快速测定火箭煤油馏程是可行的。     

镍钴/碳气凝胶的制备及电催化析氧性能研究

以海藻酸钠为原料,通过溶胶-凝胶合成法得到不同镍钴比例海藻酸水凝胶,然后通过不同温度的煅烧处理,得到不同比例镍钴/碳气凝胶电极催化剂。采用X-射线衍射(XRD)和扫描电子显微镜(SEM)等手段对产物的结构和形貌进行表征。通过电化学测试研究了各样品的电催化析氧性能和稳定性。结果表明,镍钴质量比为1∶5,275℃温度下的样品电催化析氧性能最好。     

塑料水分含量测定新方法的介绍

众所周知,塑料中存在的水分对塑料原料及其制品性能都会带来影响。目前常见的水分测试方法是卡尔费休水分测试法和烘箱法,卡尔费休水分测试法虽然能准确测定塑料中的水分含量,但是存在成本较高、测试时间较长、操作复杂和卡尔费休试剂有毒等问题。烘箱法虽然快速简单,但得到的结果并非含水量而是包含其他低挥发性物质的挥发分含量。因此,本文着重于介绍一种新的测试塑料水分方法,它能快速完成塑料水分的检测,得到塑料的准确水分含量。本文采用新方法测试塑料水分并与卡尔费休水分测试法的测试结果等进行比较。发现:氢化钙水分测试法测试的塑料材料水分含量与卡尔费休水分测试法的结果具有可比性,认为氢化钙水分测试法可作为一种测试塑料材料真实水分含量的新方法。     

Pd/WS2二维复合材料的制备及电解水制氢性能研究

首先通过锂离子插层制备了薄层WS_2纳米片,并采用软模板法在纳米片上负载了Pd纳米颗粒,得到Pd/WS_2复合材料。X射线衍射光谱(XRD)和透射电子显微镜(TEM)的结果表明Pd颗粒均匀地负载在了WS_2纳米片上。随后在H_2SO_4水溶液中对该复合材料进行电解水析氢性能测试,线性扫描伏安法(LSV)结果表明:复合材料的析氢起始电位为155 mV,塔菲尔斜率为121.79 mV·dec~(-1),总体催化性能相比于单纯的WS_2纳米片和Pd金属颗粒有很大的改善,也优于当前商用的Pd/C催化剂。采用循环伏安法(CV)测试其稳定性,结果表明Pd/WS_2复合物电极具有优良的电催化析氢稳定性。     

A thermodynamic model for wax deposition phenomena

Wax precipitation is a serious problem in the petroleum industry because it may cause obstruction in well bores, production facilities and transportation pipelines during oil/gas production. To avoid this problem it is necessary to predict the wax appearance temperature (WAT) accurately. Consequently, a reliable thermodynamic model for predicting WAT is crucial in the design of production and transportation facilities. In this work, a thermodynamic model, based on multi-solid phase theory, has been developed. In this model the vapor and liquid phase fugacities are calculated using the Modified Peng Robinson (MPR) equation of state. The solid phase fugacities of pure components are evaluated indirectly from equation of state by the fugacity ratio. Fraction properties are estimated by using PNA analysis, and a correlation is developed for evaluating enthalpy of fusion. The major aim for performing this research was to develop a thermodynamic-computerized model for predicting WAT and the amount of precipitated wax in petroleum mixtures. The model has been applied to calculate wax appearance temperature and the amount of precipitated wax for some North Sea and synthetic oils. The predicted results are in a very good agreement with experimental data.     

Study on wax precipitation characteristics of wax deposit in pipes

Wax deposit properties are a significant concern in pipeline pigging during waxy crude oil transportation. In the present work, the impacts of flow conditions and oil properties on the wax precipitation characteristics of wax deposits are investigated. A flow loop apparatus was developed to conduct wax deposition experiments using four crude oils collected from different field pipes. The differential scanning calorimetry (DSC) technique was employed to observe the wax precipitation characteristics of crude oil and wax deposit. The results show that the wax content and the wax appearance temperature (WAT) of the deposits increase with shear stress and radial temperature gradient, and decrease with radial wax molecule concentration gradient near the pipe wall. The DSC tests on the wax deposits revealed that the deposit wax content is strongly correlated to the oil wax content. Furthermore, an empirical correlation was developed to predict the wax content and the WAT of the wax deposit. Verification of the empirical correlation using the different oils indicated that the average relative error of the wax content prediction and average absolute error of WAT prediction were 13.2% and 3.6°C, respectively.     

Assessing thermomechanical properties of a reactive maleic anhydride grafted styrene-ethylene-butylene-styrene/thermoplastic polyurethane blend with temperature scanning stress relaxation method

The phenomenon of stress relaxation in thermoplastic elastomers (TPEs) is common and influences the end-use properties of polymers. Temperature scanning stress relaxation (TSSR) method extends an advanced method to study the stress relaxation of TPEs at elevated temperatures. A reactive blend system based on maleic anhydride grafted styrene-ethylene-butylene-styrene and thermoplastic polyurethane is explored for its relaxation behavior at temperature up to 200°C with TSSR meter. The relaxation spectrum revealed the transitions occurring in the blends as well as the extent of interfacial interaction present. Direct measurement of elasticity of the blends was obtained from the TSSR index (RI). Glass transition temperature of the samples was measured from dynamic mechanical analysis. The elastic nature of the blends was also pursued from the storage modulus values and results were in line with TSSR results. The density of crosslinks in the system was assessed with both TSSR and the conventional Flory-Rehner equation and a similar trend was obtained. Atomic force microscopy and scanning electron microscopy revealed the dispersed morphology of the blends.     

聚乙烯燃气管道失效模式研究进展

综述了聚乙烯（PE）燃气管道的失效形式及评估方法研究进展,详细讨论了PE燃气管道的失效机理和失效评估方法的发展方向。讨论了PE管道的韧性失效、脆性失效、焊接接头失效和表面失效的方法和种类。结果表明,PE燃气管道失效评估多为力学研究,无损检测技术还不够完善。最后对PE燃气管道无损检测的应用前景提出了展望。     

偏光显微法测定含蜡原油析蜡点的影响因素研究

在含蜡原油析蜡点测定和蜡晶特性分析等研究中,偏光显微法以其灵敏度高、接近实际、直观等优点而得到广泛应用。但该方法受测试条件和人为因素的影响较大。以阿赛线某站原油为研究对象,探讨不同热处理温度、偏光显微镜放大倍数和试样盖玻片自身缺陷等因素对含蜡原油析蜡点偏光显微测定的影响。结果表明：热处理温度对原油的析蜡点和蜡晶结构有较大的影响,盖玻片自身缺陷在一定程度上将干扰析蜡点的准确判断。     

焦炭塔堵焦阀接管部位的应力计算及高温应力测定

为算出一座焦炭塔堵焦阀接管处的管端推力（矩）数值及塔体接管部位的应力，特选用等值刚度法ＦＡＯＰ及有限元法ＭＳＣ两个标准程序分别对该塔的高温进油管系及塔体接管部位进行了柔性分析及应力计算。为了验证计算方法的正确性，还在接管部位用电测法进行了高温应力测定试验。结果证明两者数值吻合     

基于超声衰减和声速动态监测石蜡的相变过程

为研究石蜡在相变过程中内部结构和状态的改变特性,用中心频率为5 MHz的脉冲式超声波动态测量石蜡的相变过程,采集并分析不同升降温速率下的声速和声衰减信号的变化规律,结果与差示扫描量热仪(DSC)测量的热力学性质比较,并拍摄石蜡溶解过程的图像为辅助,探讨了二者由于测量原理不同导致的差异和特点。结果表明,两种方法均得到约50℃的初凝点,且二者信号反映的相变规律一致,表明利用声衰减和声速能够较好的表征石蜡在相变过程中的声学特性。超声可能成为一种新的蜡化物性质原位测量手段。     

测试方法对聚合物玻璃化温度的影响

选取环氧树脂固化物为样品,分别采用DSC法和DMA法测定了其玻璃化转变温度。结果表明,玻璃化转变温度随测定方法和条件的不同而变化,因此,在给出某种材料的玻璃化转变温度时,必须注明测定方法和条件。     

基于加速试验方法的复合材料长期寿命预测

将跨尺度失效理论(Micro-Mechanics of Failure,简称"MMF")、加速试验方法(Accelerated Testing Methodology,简称"ATM")和渐进损伤分析(Progressive Damage Analysis,简称"PDA")三种方法相结合,提出了一种可以预测复合材料长期寿命和失效过程的分析方法。对MMF失效准则进行改进,区分了基体拉伸和压缩细观失效模式。建立了MMF/ATM/PDA方法有限元计算流程,并在ABAQUS中使用用户自定义材料(UMAT)实现。通过对不同温度下复合材料纵向和横向单向板的拉伸、压缩试验测得静载和疲劳寿命,得到复合材料MMF/ATM细观临界值。采用MMF/ATM/PDA方法对准各向同性开孔板压缩长期寿命进行了预测,并对破坏过程进行了模拟,分析了纤维和基体的失效过程。试验结果和预测结果吻合良好,验证了方法的合理性。     

Analysis of paraffin precipitation from petroleum mixtures by means of DSC: Iterative procedure considering solid-liquid equilibrium equations

Wax deposition is a well known flow assurance risk in crude oil production due to temperature decrease which depends mainly on the crude oil nature and the type and content of paraffin. The prevention of this problem requires a detailed characterization of the crude oil and the availability of reliable predictive models.The experimental determination and quantification of the precipitation process is quite complex and time consuming and simpler techniques are of interest to carry out such study. Among them, differential scanning calorimetry (DSC) technique is appropriate to develop routine essays and has been extensively applied to determine wax appearance temperature in crude oil and fractions because the simplicity and fast response of the technique.However, the determination of wax precipitation curve from a quantitative DSC interpretation is usually based on pure n-alkane properties and involves some difficulties. In this work, a new procedure has been developed including the effect of the fluid composition on the precipitation temperature and the melting heat. Solid-liquid equilibrium equations were introduced through a simplified thermodynamic model in the integration procedure resulting in an iterative method combining experimental and calculated values. The final method yields the wax appearance temperature (WAT), the full wax precipitation curve and the estimated wax composition.In order to validate the procedure, several crude oil fractions were used as standards due to the advantage of a narrow n-alkane distribution. Experimental characterization for the cloud point temperature, the n-alkane distribution (determined by gas chromatography with mass detector, GCMS) and DSC was carried out. The agreement between experimental results and those obtained from the DSC interpretation is a good check for the proposed procedure.