差示扫描量热法测定石蜡熔点的研究

采用差示扫描量热(DSC)技术,模拟石蜡熔点(冷却曲线法)测试过程,测定石蜡的熔点。研究了起始温度、终止温度、吹扫气(氮气)流量、升降温速率、试样质量、恒温时间、样品制备方式、升降温次数等对测试结果的影响,确定了DSC法测定石蜡熔点的适宜条件,考察了DSC法与标准方法(GB/T 2539—2008)的偏倚。结果表明,采用DSC法测定石蜡熔点时的升温速率宜为10℃/min,降温速率宜为5℃/min,试样在高于预估熔点20～30℃下熔融时间不应超过1 h。通过采用6台不同型号的DSC仪器对14个牌号石蜡样品进行测试,计算出DSC法与标准方法的偏倚为-1.14℃。DSC法操作简单、试样用量少、检测速率快、重复性好,可作为控制分析手段,快速准确地测定石蜡的熔点。     

采用差示扫描量热法测定蜡滴熔点

采用差示扫描量热（DSC）法测定蜡滴熔点,研究了升（降）温速率、升温次数对测试结果的影响,并在最优条件下考察了DSC法测蜡滴熔点的重复性、准确性和再现性。结果表明:确定熔融曲线终止边的拐点温度为DSC法的滴熔点;DSC法测蜡滴熔点的最优条件为:第1次升（降）温速率均为20 ℃/min,第2次升温速率为5 ℃/min;该方法的重复性在0~0.2 ℃,再现性在0~1.1 ℃,均满足GB/T 8026—2014的要求。     

差示扫描量热法测定费托蜡滴熔点的研究

采用DSC法对费托蜡滴熔点进行测定,研究了升降温速率、升温次数、起始和终止温度、氮气吹扫气流量、平衡时间、试样质量等对测试结果的影响,确定了DSC法测定滴熔点的适宜条件,考察了DSC法测定费托蜡滴熔点的重复性、准确性和再现性。实验结果表明,DSC法测定费托蜡滴熔点的适宜条件为：第一次升降温速率20℃/min、第二次升温速率5℃/min、熔融过程的起始温度为室温、终止温度高于预估滴熔点20～30℃、取样质量5～10 mg、氮气吹扫气流量10～50 mL/min、熔融与结晶过程转变平衡时间2 min。DSC法测定费托蜡滴熔点操作简单、试样用量少、检测速率快、重复性和再现性良好、测试结果准确,可作为传统方法的替代手段。     

采用DSC法测定原油的比热容

采用DSC法测定了原油的比热容,以蒸馏水为标准物质,考察了升温速率、试样用量和工作气流量等因素对测定结果相对偏差的影响,得到了较佳的实验条件。实验结果表明,将实验误差控制在最小值的实验条件为:试样皿和参比皿的质量偏差控制在±0.1 mg内、试样用量5 mg左右、工作气流量20 mL/min、升温速率2℃/min。通过将测试的原始数据进行修正,可进一步降低DSC法的系统误差,最终可将系统误差降至2%以内,提高了DSC法测定原油的比热容的精确度。与绝热量热法相比,采用DSC法测定原油的比热容,操作简单,可行性强,可满足实验测定要求。     

DSC法测定汽油馏分的低温比热容

用差示扫描量热计（ＤＳＣ）测定５个汽油馏分（沸点小于２００℃）在２４３～２９９Ｋ范围内的比热容,测量误差在±２％以内。比较了比热容实测值与国外常用计算方法的预测结果。还由比热实验值计算低温焓,它们与铜量热计测得的高温焓间具有较好的一致性     

干酪根的差示扫描量热法(DSC)的研究

作者以抚顺、茂名、黄县油页岩干酪根和黄县褐煤有机质为试样,采用差示扫描量热法(DSC).对干酪根的热演化进行研究,并根据干酪根结构参数的变化,讨论其母质类型及油气生成潜力.      

石蜡微胶囊中脲醛树脂壁材渗透性的研究

利用差示扫描量热法研究了石蜡微胶囊中脲醛树脂壁材对水及甲苯的渗透性 ,结果表明 ,水不能透过脲醛树脂壁材 ,而甲苯则易透过脲醛树脂壁材。因此 ,该石蜡微胶囊不能用于芳香族溶剂存在的场合。     

酮苯脱蜡装置蜡下油中固态烃的组成研究

以中国石化高桥分公司3号酮苯脱蜡装置加工的减二线和减五线蜡下油为原料,分别采用低温发汗和酮苯脱蜡脱油试验的方法,从轻馏分（减二线）的蜡下油中,得到了固态烃化学组成以正构烷烃为主的低熔点石蜡,从重馏分（减五线）的蜡下油中,得到了固态烃化学组成以大量的环烷烃和异构烷烃为主的低熔点微晶蜡。对低熔点石蜡分析结果表明,该石蜡具有吸热温度范围窄、吸热量高、相变温度和峰顶温度适中等特点,可以开发为相变石蜡产品。同时,低熔点微晶蜡的化学组成较好地解释了一直以来工业生产中一段脱蜡二段脱油工艺\"对轻馏分效果好,而对重馏分效果差\"的现象,为今后生产高熔点、低含油量石蜡方案提供了依据。     

Correlations Between the Pour Point/Gel Point and the Amount of Precipitated Wax for Waxy Crudes

The amount of precipitated wax is one of the key factors that governs the flow properties of waxy crudes. Experimental results of 24 crudes have shown that approximately 2 wt% precipitated wax is sufficient to cause a virgin waxy crude gelling. Accordingly, a correlation between the pour point and the temperature at which 2 wt% of wax has precipitated out from a crude oil; i.e., T_c(2 wt%), and a correlation between the gel point and T_c(2 wt%) have been developed. The proposed correlation of the pour point is in accordance with the correlation developed by Letoffe et al. (1995) on the basis of 14 crudes from eight countries. The development of the gel point correlation and further verification of the pour point correlation indicate that there is a relationship between the gelling of virgin waxy crudes and the amount of precipitated wax. According to these correlations and the amount of precipitated wax, which can be determined only with a little sample by thermodynamic models or Differential Scanning Calorimetry (DSC) experiment, the gel point and pour point of virgin waxy crude can be predicted even if the oil sample is very limited. Heat treatment and chemical treatment can greatly improve flow behavior of waxy crudes, and more precipitated wax is present when the beneficiated (thermally beneficiated or PPD-beneficiated) crude oils gel. Experimental results showed that approximately two or three times the amount of precipitated wax presents at the gelling temperature when the oils were in their beneficiated (thermally beneficiated or PPD-beneficiated) conditions.     

Correlations Between the Pour Point/Gel Point and the Amount of Precipitated Wax for Waxy Crudes

Abstract:

The amount of precipitated wax is one of the key factors that governs the flow properties of waxy crudes. Experimental results of 24 crudes have shown that approximately 2 wt% precipitated wax is sufficient to cause a virgin waxy crude gelling. Accordingly, a correlation between the pour point and the temperature at which 2 wt% of wax has precipitated out from a crude oil; i.e., T _c (2 wt%), and a correlation between the gel point and T _c (2 wt%) have been developed. The proposed correlation of the pour point is in accordance with the correlation developed by Letoffe et al. (1995) Letoffe, J. M., Claudy, P., Kok, M. V., Garcin, M. and Vollet, J. L. 1995. Fuel, 74(6): 810–817. [CSA][CROSSREF][Crossref] , [Google Scholar] on the basis of 14 crudes from eight countries. The development of the gel point correlation and further verification of the pour point correlation indicate that there is a relationship between the gelling of virgin waxy crudes and the amount of precipitated wax. According to these correlations and the amount of precipitated wax, which can be determined only with a little sample by thermodynamic models or Differential Scanning Calorimetry (DSC) experiment, the gel point and pour point of virgin waxy crude can be predicted even if the oil sample is very limited. Heat treatment and chemical treatment can greatly improve flow behavior of waxy crudes, and more precipitated wax is present when the beneficiated (thermally beneficiated or PPD-beneficiated) crude oils gel. Experimental results showed that approximately two or three times the amount of precipitated wax presents at the gelling temperature when the oils were in their beneficiated (thermally beneficiated or PPD-beneficiated) conditions.     

Physical Properties of Petroleum Waxes. I. Effect of Oil Content

Abstract

The effect of oil content on the physical properties of five microcrystalline waxes having widely different oil content have been investigated. It has been observed that the physical properties are affected to a great extent by the variation in oil content. Oil content has a profound effect on viscosity, hardness, and crystallinity of waxes. The effect is not so profound in the case of melting point.     

Physical Properties of Petroleum Waxes. I. Effect of Oil Content

The effect of oil content on the physical properties of five microcrystalline waxes having widely different oil content have been investigated. It has been observed that the physical properties are affected to a great extent by the variation in oil content. Oil content has a profound effect on viscosity, hardness, and crystallinity of waxes. The effect is not so profound in the case of melting point.     

高含蜡柴油用PCH降凝剂应用效果评价

简述了国内外降凝剂发展概况,分析了南阳石蜡精细化工厂生产的柴油对目前国内外降凝剂感受性差的主要原因,选择PCH降凝剂作为高含蜡柴油降凝剂。实验及工业应用表明,PCH降凝剂能有效地降低该厂柴油的冷滤点,当加入量为0．05％,调合柴油的冷滤点下降4℃,满足了油品的使用标准;并使柴油收率提高2％,经济效益明显。PCH降凝剂与现行国内外降凝剂产品相比,具有独特效果,对高含蜡柴油具有极好的推广应用价值。     

新型蜡晶分散助剂的制备及柴油降凝研究

以乙二胺、丙烯酸甲酯、丙烯酸高碳酯为原料,乙醇钠为催化剂,通过Michael加成和酰胺化反应,合成了一种含有长链烷基和多氨基、酰胺基极性官能团的柴油蜡晶分散助剂。红外光谱检测表明产物与理论设计相符。降凝实验表明,单独添加1000μg/g蜡晶分散助剂时,冷滤点降低2—4℃;与降凝剂T1804复配时,凝点最大降低15℃,冷滤点最大降低9℃;与自制降凝剂复配后,凝点最大降低11℃,冷滤点最大降低7℃。说明制备的蜡晶分散助剂与降凝剂有良好的协同效应。     

高滴熔点微晶蜡中碳数分布的测定

采用冷柱头进样的高温气相色谱技术,建立了测定高滴熔点微晶蜡中正构和非正构烃类含量及碳数分布的方法。对滴熔点在90℃以下的微晶蜡进行测定。实验表明,使用大口径高温毛细管柱可以分析碳数在72以下的微晶蜡。方法快速,准确,实用性强。     

络合-分光光度法测定食品级石蜡中的痕量铅

食品级石蜡中的铅与双硫腙能够生成红色络合物,采用分光光度法测定络合溶液的吸光度,建立溶液的吸光度与铅含量回归方程。实验证明,络合溶液在波长510nm处有最大吸收峰,当溶液中铅质量分数在0～10 0mg/kg内,铅含量与吸光度成良好的线性关系,检出限为0 1mg/kg。该方法适用于食品级石蜡、微晶蜡中铅的测定。