溶剂芳香性对渣油沥青质稳定性的影响

为深入认识固定床渣油加氢-催化裂化双向组合技术溶剂芳香性与沥青质稳定性的关系，采用Flory-Huggins模型考察了沙特轻质原油常压渣油的沥青质稳定性，并用溶解度参数关联了溶剂的芳香性。结果表明，Flory-Huggins模型可用于研究渣油体系的沥青质稳定性。随着溶剂芳香性的增加，其溶解度参数增大，沥青质稳定性增强。密度较大、H/C原子比较小的溶剂具有较大的溶解度参数，对沥青质的稳定性较有利。     

RICP技术中氢气溶解度的研究

基于渣油加氢试验数据,采用Aspen Plus软件建立了固定床渣油加氢热高压分离器的氢气-渣油-芳烃气液平衡体系,考察了溶剂萘、蒽、屈、芘、FCC回炼油对液相溶解氢量的影响。结果表明：当加入芳烃溶剂后,液相的氢溶解度增加;加氢处理后,液相的氢溶解度增加。基于加入芳香性溶剂有利于沥青质稳定性的认识,进一步发现,液相氢溶解度增大对沥青质稳定性是不利因素。研究结果对RICP技术中芳烃对沥青质稳定性的作用有了更深入的认识。     

RICP技术中氢气溶解度的研究

基于渣油加氢试验数据，采用Aspen Plus软件建立了固定床渣油加氢热高压分离器的氢气-渣油-芳烃气液平衡体系，考察了溶剂萘、蒽、屈、芘、FCC回炼油对液相溶解氢量的影响。结果表明：当加入芳烃溶剂后，液相的氢溶解度增加；加氢处理后，液相的氢溶解度增加。基于加入芳香性溶剂有利于沥青质稳定性的认识，进一步发现，液相氢溶解度增大对沥青质稳定性是不利因素。研究结果对RICP技术中芳烃对沥青质稳定性的作用有了更深入的认识。     

沥青质稳定性在渣油加氢过程中的变化规律

为考察固定床渣油加氢-催化裂化双向组合（RICP）技术中多环芳烃改善杂质脱除效果和抑制催化剂积炭的原因,建立了基于Flory-Huggins活度系数模型考察380 ℃、14.0 MPa条件下沥青质稳定性的方法。基于上述方法,建立了衡量渣油加氢反应中活性氢使用效率的参数A/B：A越大,活性氢用于杂质脱除的效率越高;B越小,活性氢用于沥青质加氢的效率越高。研究结果表明,经过加氢后,渣油轻质化程度增加,渣油溶氢量增加,沥青质与渣油（含溶解氢）溶解度参数之差增加,沥青质稳定性变差;在380 ℃、14.0 MPa条件下,采用RDM-32,RDM-53,RCS-31催化剂以体积比40：10：50级配时,沙轻常压渣油加氢过程的A/B值最大;在此基础上,引入高芳香性馏分有利于进一步提高加氢过程的A/B值。多环芳烃改善杂质脱除效果并抑制催化剂积炭的原因在于：多环芳烃优化了活性氢用于杂质脱除和沥青质加氢的效率。     

胶质对沥青质稳定性的影响

为了进一步研究胶质与沥青质之间的相互作用对沥青质稳定性的影响,在分析表征沥青质和胶质的平均结构单元并计算溶解度参数的基础上,向沥青质模型油（沉积物计为AS沉积物）中分别加入胶质NBR和胶质VRR得到AS+NBR沉积物和AS+VRR沉积物,通过分析沉积物颗粒粒径分布,考察胶质对沥青质稳定性的影响程度。结果表明：沥青质的芳香性最强、溶解度参数最大（20.61 MPa1/2）,胶质VRR的芳香性和溶解度参数（17.80 MPa1/2）高于胶质NBR;在沥青质模型油中,随着胶质VRR浓度的增加,沉积物颗粒粒径减小,而胶质NBR的加入并不能使沉积物颗粒粒径变小,当其质量浓度达到1 000 mg/L时,沉积物颗粒粒径反而增加。3种沉积物的热重、凝胶渗透色谱（GPC）和X射线衍射（XRD）分析结果表明：胶质与沥青质之间存在缔合作用,使沉积物芳香片层厚度和直径减小、层间距增大,芳香片层数减小;3种沉积物的相对分子质量从大到小的顺序为AS沉积物＞AS+NBR沉积物＞AS+VRR沉积物。因此芳香性强、溶解度参数接近沥青质的胶质VRR能更好地分散稳定沥青质,使得沉积物颗粒粒径变小、石墨化程度减弱,从而不易沉积和结焦。     

掺配FCC油浆的溶剂脱沥青组合工艺研究

在连续式溶剂脱沥青试验装置上考察了掺配ＦＣＣ油浆对渣油溶剂脱沥青过程的影响,油浆的加入使脱沥青油收率增加,脱沥青油和脱油沥青的质量也得到了明显提高。提出了试验用渣渍和油浆的结构模型 据此计算得到它们的溶解度参数。根据渣烃类溶剂中溶解平衡理论和组成分析结果,揭示了掺同浆改善溶剂脱沥青过程的机理。     

基于特性黏度法计算沥青质胶团直径和溶剂化效应——分散体系活化状态表征

在委内瑞拉常压渣油中添加不同比例十八醇,考察十八醇对强化减压蒸馏效果的影响。结果表明,十八醇具有良好强化效果,最大蜡油净增收率为4.01%。测定渣油(沥青质)-甲苯溶液的黏度,根据Einstein黏度定律和Pals-Rhodes方程,计算得到了沥青质胶团直径D和溶剂化参数K,结果表明,特性黏度法测得的沥青质尺寸为沥青质胶核外吸附-溶剂化层的直径,其数值受溶剂化效应的影响,测定渣油-甲苯溶液黏度可以表征渣油体系中沥青质胶团尺寸。对于添加了十八醇的渣油体系,其沥青质胶团直径减小、溶剂化效应降低,变化趋势与减压蜡油净增收率有良好的对应关系,可以采用特性黏度法计算沥青质胶团直径和溶剂化效应,来预测石油分散体系的活化状态。     

渣油悬浮床加氢裂化尾油化学结构 及其裂化性能评价

 采用改进的B-L(Brown-Ladner)法和密度法，分析了克拉玛依渣油悬浮床加氢裂化尾油及其饱和分、芳香分、胶质、沥青质的化学结构；利用芳香性不同的溶剂对该尾油进行处理，在高压反应釜中评价了尾油、渣油和处理后尾油的裂化性能。结果表明，尾油平均分子结构中烷基碳率小于渣油分子，芳香碳率、芳环数和缩合指数大于渣油分子；尾油的裂化转化率比渣油低，缩合转化率比渣油高，对催化剂的感受性下降；采用低芳香性溶剂处理可改善尾油的反应性能，达到悬浮床加氢裂化循环油的要求。     

减压渣油胶体稳定性的分子模拟研究

分子结构特性决定分子间相互作用,进而决定其溶解性能。通过分子模拟研究减压渣油不同结构分子的分子间相互作用、互溶性及由此导致的渣油胶体稳定性。研究表明,芳环数目越多、烷基侧链越短的分子结构内聚能密度越大,溶解度参数越大。在渣油体系中,沥青质、重胶质分子聚集形成胶核,饱和烃、芳香烃、轻胶质分子形成连续相。胶质分子结构影响其胶溶性能,侧链长度适中的胶质分子,其与沥青质、芳香分互溶性好,胶溶性能优异;沥青质的聚集程度随胶质分子含量的增加而降低。芳香分、胶质分子的协同作用使沥青质、饱和烃分子稳定存在于同一体系中,因此渣油胶体稳定性取决于不同分子结构的连续性和配伍性。     

芳香性对渣油加氢反应的影响

研究掺入不同芳香性重馏分油对渣油加氢反应的影响。结果表明，渣油中掺入馏分油的芳香性越高，对脱金属、脱沥青质反应的促进作用越明显，对脱硫、脱残炭反应影响不大；而掺入馏分油的饱和性高则反应效果较差。该结果揭示了掺入馏分油的芳香性可以改变渣油的胶体结构，进而影响渣油的加氢反应性能。     

Intelligent Modeling of Asphaltene Precipitation in Live and Tank Crude Oil Systems

Abstract

The study of asphaltene precipitation properties has been motivated by their propensity to aggregate, flocculate, precipitate, and adsorb onto interfaces. The tendency of asphaltenes to precipitation has posed great challenges for the petroleum industry. The most important parameters in asphaltene precipitation modeling and prediction are the asphaltene and oil solvent solubility parameters, which are very sensitive to reservoir and operational conditions. The driving force of asphaltene flocculation is the difference between asphaltene and the oil solvent solubility parameter. Since the nature of asphaltene solubility is yet unknown and several unmodeled dynamics are hidden in the original systems, the existing prediction models may fail in prediction the asphaltene precipitation in crude oil systems. One of ways in modeling such systems is using intelligent techniques that need some information about the systems; so, based on some intelligent learning methods it can provide a suitable model. The authors introduce a new implementation of the artificial intelligent computing technology in petroleum engineering. They have proposed a new approach to prediction of the asphaltene precipitation in crude oil systems using fuzzy logic, neural networks, and genetic algorithms. Results of this research indicate that the proposed prediction model with recognizing the possible patterns between input and output variables can successfully predict and model asphaltene precipitation in tank and live crude oils with a good accuracy.     

添加剂对渣油加氢脱金属性能的影响

以不同种类和不同含量高芳香性的催化裂化产物重循环油(HCO)和轻循环油(LCO)作为添加剂,考察了其对常压渣油加氢脱金属反应(HDM)性能的影响。结果表明,HCO和LCO添加剂的加入,可改善渣油在反应过程中的扩散性能,促进渣油中沥青质的溶解,从而提高渣油的HDM性能,其对加氢脱镍(HDNi)性能的提高更优于加氢脱钒(HDV)。同时发现,加入高芳香性添加剂后,渣油HDM过程中S、N和CCR的脱除率均有提高,反应产物的相对分子质量分布明显向低相对分子质量方向移动;随着LCO添加剂含量的增加,渣油的HDNi、HDV性能逐步提高,但当LCO质量分数增加到20%后,其提高渣油HDM性能的作用稍有下降。     

沥青质沉淀点的测定与模型化计算

通过自行设计、组装了一套采用透光率法测定原油体系沥青质沉淀点的实验装置,并采用该仪器测定了6个浓度的沥青质+甲苯体系及4个浓度的原油+甲苯体系的正戊烷和正己烷沥青质沉淀点。模型计算中采用目前具有代表性的Hirschberg沥青质沉淀溶解度模型以拟合实验数据。结果发现由实验数据回归得到的原油溶解度参数明显高于状态方程法的计算结果;原始条件下沥青质的溶解度参数值明显低于被提纯后沥青质的溶解度参数值。     

Stability of Water-in-Crude Oil Emulsions: Effect of Oil Aromaticity,Resins to Asphaltene Ratio,and pH of Water

Abstract

The formation of tight water-in-oil emulsions during production and transport of crude oils is a great problem challenging the petroleum industry. Tremendous research works are directed to understanding the mechanism of formation, stabilization, and controlling of oil field emulsions. This article presents experimental results of some of the factors controlling the formation and stabilization of water-in-crude oil emulsions. In this study, asphaltenes and resins separated from emulsion samples collected from Burgan oil field in Kuwait have been used to study emulsion stability. Model oils of resin to asphaltene ratio of 5:1 and toluene-heptane mixtures have been used to study the effect of oil aromaticity on emulsion stability. Results indicate that at low toluene content (below 20%) or high content (above 40%) less stable emulsions are formed. At a threshold value of 30% toluene, a very tight model oil emulsion is formed. The effect of resins to asphaltene (R/A) ratio on stability of model oil has also been investigated. Results reported in this paper show that as the R/A increases the emulsions become less stable. The effect of pH on stability of model oil emulsion made of 50/50 heptane-toluene mixture having R/A ratio of 5:1 have been studied. Experimental results revealed that as the pH of the aqueous phase of model oil increased from 2 to 10, the emulsion became less stable. At high pH, the asphaltene particles are subjected to complete ionization leading to destruction of the water-oil interface and eventually breakdown of the emulsion.     

POLYMER SOLUBILITY THEORY PREDICTS EFFICIENCY OF RESIDUAL OIL EXTRACTION BY POLAR SOLVENTS

ABSTRACT

Light paraffinic solvents (C2 to C7) have traditionally been utilized by the petroleum refining industry to extract oils from crude distillation residua. Extracted oils constitute feedstock to lubricants manufacture and, to a lesser extent, additional cracking stock. More recent literature reveals a growing interest in polar, non-hydrocarbon partially oil-soluble solvents such as alcohols, ketones, and esters of lower carboxylic acids. In this work, articles and patents which report the separation of residua into asphalt and extracted oil by means of polar solvents are briefly reviewed, and the separation performance of same of those solvents is correlated to the solute-solvent interaction parameter (?) in the Flory-Huggins theory of polymer solubility. The three dimensional solubility parameter (δ) approach is followed to estimate ? for the solvents of interest at the appropriate operating conditions. The saturate, aromatic, and polar compounds fractions of a bitumen are characterized by solubility parameters equal to the values of δ of the solvents or mixtures thereof used by the standard ASTM D-2007 chromatographic fractionation of the deasphaltenated oil (DAO). A mean value of ? is found for every DAO-solvent pair, treatment ratio and temperature. For each solvent considered, yields of extracted oil at varying operating conditions (temperature, pressure, solvent /feed ratio) are found to be well correlated to ?, in according with theoretical predictions that the lower a value of ? a solvent has for a given solute, the better it dissolves the solute and the higher the yield.

It is suggested that this type of approach could supply criteria to select solvents and operating conditions for applications requiring high yields (to produce additional cracking stock) or lower yields but high rejection of metals and heteroatoms (e.g. for lube oil bases extraction).