Prediction of Liquid Viscosities of Petroleum Fractions

A general equation is proposed for predicting the liquid viscosities of petroleum fzac-riots based on a generalied pseudocompound method in which pure hydrocarbons and undefined hydrocarbon mixtures or petroleum fractions are treated as a hypothetical pure substance called pseudocompound which is chaxacterized only by a boiling point and a density. The equation is tested by using the liquld viscosities of the petroleum fractlons of typical American crude oils and crude oils from major oil producing sreas. Good agreement between the predicted and experlmental viscosities for the petroleum fractions is obtained.     

A correlation for predicting liquid viscosities of petroleum fractions

A correlation has been developed for estimating the liquid viscosities of petroleum fractions at 100°F and at 210°F. When used with the ASTM viscosity chart (or its analytical equivalent), the new correlation provides a method for the prediction of viscosity-temperature behavior of fractions from the Watson characterization factor and specific gravity. Essentially an extension of an API Data Book viscosity nomograph, the proposed correlation substantially improves on the accuracy and increases the range of applicability of this method. Greatest accuracy is achieved for petroleum fractions in the kerosene to heavy gas oil range, although acceptable accuracy for most engineering calculations is also obtained for lube oils and for many complex pure heavy hydrocarbons.     

Testing various mixing rules for calculation of viscosity of petroleum blends

Seventeen mixing rules reported in the literature used for predicting kinematic viscosity of petroleum and its fractions were examined for accuracy by comparing the estimated values with the experimental viscosities of four crude oils (21.31, 15.93, 12.42 and 9.89°API gravity) and their blends with a diluent (diesel) at several proportion. Tested mixing rules were classified as pure mixing rules, mixing rules with a VBI parameter, and mixing rules with an additional parameter. The results indicated a general trend to fail as the crude oil API gravity decreased, although at high temperature of analysis the predictions improved. After calculating standard errors for all predictions, only four of these rules showed acceptable accuracy (Chevron, Walther, Einstein and Power law), nevertheless no rule was capable of estimating viscosity for all the crude oils, highlighting that predicting viscosity is a challenging task. This general result led a further analysis for testing the accuracy of mixing rules in predicting viscosity for light distillates (naphtha, diesel and vacuum gas oil) and their blends; basically the same results were found, although a fifth rule (Chririnos) showed good agreement with experimental values.     

Improved empirical correlation for petroleum fraction composition quantitative prediction

The prediction of the composition of petroleum fractions and pure hydrocarbon mixtures is a sensitive operation. Up till now, the already developed correlations in the literature are based on experimental data of crude oils. In this work, a new method is proposed for correlations elaboration based on the use of pure hydrocarbons specific data. This technique enables the characterization of the composition (wt%), in paraffins, naphthenes and aromatics, of pure hydrocarbon mixtures and petroleum fractions issued from different crude oils, according to their physical properties that are easily accessible such as normal boiling point (T_b), density (d), refractive index (n) and carbon to hydrogen weight ratio (CH).     

Temperature effect on the viscosities of palm oil and coconut oil blended with diesel oil

One of the major difficulties in using crude vegetable oils as substitute fuels in diesel engines is their relatively high viscosities. Increasing the temperature of the crude vegetable oil, blending it with diesel oil, or the combination of both offers a simple and effective means of controlling and lowering the viscosities of vegetable oils. This work reports viscosity data, determined with a rotational bob-and-cup viscometer, for crude palm oil and cononut oil blended with diesel oil over the temperature range of 20–80°C and for different mixture compositions. All the test oil samples showed a time-independent newtonian type of flow behavior. The reduction of viscosity with increasing liquid temperature followed an exponential relationship, with the two constants of the equation being a function of the volume percentage of the vegetable oil in the mixture. A single empirical equation was developed for predicting the viscosity of these fuel mixtures under varying temperatures and blend compositions.     

Distribution of mutagenic activity in petroleum and petroleum substitutes

Several petroleum crude oils and shale- and coal-derived petroleum substitutes have been fractionated by chemical class and the fractions have been tested for mutagenic activity. Crude petroleum substitutes tend to exhibit greater mutagenicities than do petroleum crude oils but the mutagenicity is reduced to comparable levels in low-boiling distillates and samples which have been hydrotreated. The mutagenicity is caused by alkaline and neutral constituents of the petroleum substitutes, but only neutral constituents for the petroleum crudes. The mutagenic components constitute less than ten per cent of the mass of the samples.     

Studies on corrosion control of naphtha fractions in overhead condensing system using laboratory distillation device

Corrosion in the overhead condensing system of atmospheric distillation units is a common occurrence in petroleum refineries worldwide. These corrosion problems are influenced by the presence of three phases: vapours, liquid hydrocarbons and aqueous phase containing hydrochloric acid formed during distillation by decomposition of chloride salts of calcium and magnesium.Present studies highlight the corrosion control of naphtha fractions of Bombay High and Dubai crude oils in laboratory distillation device by chemical treatment using various corrosion inhibitors having different functional groups. These studies were carried out using two phase systems (aqueous-hydrocarbon) in the distillation device having facilities for monitoring the corrosion and temperatures in vapour condensing region and liquid condensate. Corrosion monitoring was carried out by potentiodynamic polarization technique and dissolved iron analysis using inductively coupled plasma atomic emission spectroscopy (ICPAES). Experimental findings indicate that Dubai naphtha fraction is more corrosive in nature when compared to Bombay High naphtha. This observation can also be explained on the basis of characterization of both crude oils and their naphtha fractions. At normally recommended dosage level as in refinery overhead systems, water soluble corrosion inhibitors are more effective than hydrocarbon soluble ones in the vapour condensing region as well as in the liquid condensate of both naphtha fractions.     

基于1H NMR测定和基团贡献法预测石油馏分的热化学性质

测定了两种原油 2 0个石油馏分的¹H NMR谱和氢、碳元素含量等结构参数 ,以及馏分的燃烧焓、蒸发焓等热化学性质 .假设每个石油馏分仅由CH₃ 、CH₂ 、CH、ACH和C这 5种简单基团构成 ,基于¹H NMR测定和元素分析结果解出石油馏分平均分子结构中的基团数目 ,再用纯有机物的基团贡献法预测石油馏分的燃烧焓、蒸发焓 ,预测值与实验数据吻合良好     

Investigating the process of heavy crude oil steam cracking over disperse catalysts. I: Selection of optimal steam cracking conditions without catalyst

The process of heavy crude oil steam cracking using semi-flow (with respect to water) and steadystate regimes at 425°C without catalyst is investigated. It is established that in the case of a semi-flow regime, water acts predominantly as a physical agent facilitating the distillation of hydrocarbon fractions and thus preventing their transformation into petroleum coke. A reduction in coke yield is observed for a steady-state regime in comparison to a semi-flow regime; the introduction of water results in enhanced conversion of the high-boiling fraction and an increased yield of light fractions in the composition of liquid products. Based on the obtained data, it is concluded that water plays a positive role during the conversion of heavy crude oil, and that the steam cracking process is promising for production of lighter synthetic and/or semi-synthetic oils.     

Hydrocracking of petroleum vacuum distillate containing rapeseed oil: Evaluation of diesel fuel

Hydrocracking of pure petroleum vacuum distillate and the same fraction containing 5 wt.% of rapeseed oil was carried out at 400 and 420 °C and under a hydrogen pressure of 18 MPa over commercial Ni-Mo catalyst. Reaction products were separated by distillation into kerosene, gas oil and the residue. Fuel properties of fractions suitable for diesel production were evaluated (gas oils and remixed blends of kerosene and gas oil). Gas oils obtained from co-processing showed very good fuel properties as the remixed distillates did. Gas oil obtained from co-processing at 420 °C showed also reasonable key low-temperature properties (cloud point: −23 °C, CFPP: −24 °C) similar to those of gas oil obtained from pure petroleum raw material processing.     

基于1H NMR测定和基团贡献法预测石油馏分的热化学性质

测定了两种原油 2 0个石油馏分的¹H NMR谱和氢、碳元素含量等结构参数 ,以及馏分的燃烧焓、蒸发焓等热化学性质 .假设每个石油馏分仅由CH₃ 、CH₂ 、CH、ACH和C这 5种简单基团构成 ,基于¹H NMR测定和元素分析结果解出石油馏分平均分子结构中的基团数目 ,再用纯有机物的基团贡献法预测石油馏分的燃烧焓、蒸发焓 ,预测值与实验数据吻合良好     

Viscosities of coal—water—methanol mixtures

A plot of viscosity measurements for coal—water—methanol mixtures vs. percentage methanol in the liquid indicates that the viscosities of both coal—water and coal—alcohol slurries are increased by the addition of the second liquid. The shape of the slurry viscosity curve is very similar, on a greatly exaggerated scale, to the plot of viscosity versus percentage methanol for the pure liquid mixtures. Measurements were made as a part of a test program involving coal—water-methanol fuels. Initial mixtures were 60 wt% Pittsburgh seam coal in liquids composed of varying proportions of water and methanol. Slurries of Montana Rosebud and Texas Lignite coals in water—methanol mixtures also displayed viscosity maxima, but at different fractions of methanol. There was no viscosity peak for 40, 50 or 55% petroleum coke slurries. Slurries of ground glass in water-methanol mixtures were evaluated for comparison and a viscosity maximum was observed, although the peak occurred at a methanol concentration somewhat lower than it occurs in the pure liquid mixture.     

基于Patel-Teja状态方程的统一粘度模型(Ⅱ)应用于油气藏流体粘度的预测

基于(I)报根据pVT和Tμp图形的相似性和Patel-Teja状态方程建立的预测纯流体气、液相粘度的统一模型,通过引入常规的状态方程参数的混合规则,将其应用于二元轻烃混合物共计1894个数据点及模拟天然气高压粘度的预测,平均相对误差分别为13.78%和16.75%;应用于油藏原油和天然气高压粘度的预测,结果优于现有的有关油气藏流体粘度模型.     

Removal of naphthenic acids from a vacuum fraction oil with an ammonia solution of ethylene glycol

A new method to remove and purify the naphthenic acids in heavy fractions of petroleum is studied in this paper. An ammonia solution of ethylene glycol was used as the acid removal reagent by mixing with the petroleum fraction and then allowing the two phases to separate, with the naphthenic acids being extracted from petroleum fractions. The naphthenic acids were recovered by heating the ammonia solution containing naphthenic acids to release NH₃ and decompose the naphthenic acid ammonia salt. Petroleum ether was used to purify the naphthenic acids by extracting the neutral oils from the acid removal reagent. Data indicated that the optimal extraction temperature was in the range of 50–60 °C and the optimal NH₃ content in ethylene glycol was 3–5%. The contact time should be more than 10 min with the reagent/oil ratio being more than 0.3 (wt/wt). Acid removal can be greater than 85%. After purification by petroleum ether, the purity of naphthenic acids can be greater than 90%.     

Liquid to Semisolid Rheological Transitions of Normal and High-oleic Peanut Oils upon Cooling to Refrigeration Temperatures

Rheological transitions of peanut oils cooled from 20 to 3 °C at 0.5 °C/min were monitored via small strain oscillatory measurements at 0.1 Hz and 1 Pa. Oils were from nine different cultivars of peanut, and three oils were classified as high-oleic (approximately 80% oleic acid). High-oleic oils maintained an overall liquid-like character at 3 °C for 2 h. In contrast, several normal (non high-oleic) peanut oils displayed a predominantly elastic (solid-like) response after 2 h at 3 °C. Increases in viscoelasticity were associated with lipid crystallization events as confirmed by DSC. The higher (p < 0.001) liquid viscosities and increased (p < 0.001) contents of oleic acid, which has a more non-linear structure as compared to other fatty acids typical in these oils, were hypothesized to hinder crystallization in high-oleic oils. Changes in viscoelasticity at 3 °C were greatest for three normal oils that had the significantly (p < 0.001) highest content of C20:0 and/or C22:0 fatty acids, and these long, saturated hydrocarbon chains are hypothesized to promote crystallization. No peanut oil maintained clarity after 5.5 h at 0 °C (modified cold test used to screen salad oils); however, these data as a whole suggest strategies for breeding and/or processing peanut oils for enhanced resistance to crystallization. The use of trade names in this publication does not imply endorsement by the United States Department of Agriculture: Agricultural Research Service.     

New correlation for predicting the viscosity of heavy petroleum fractions

A new, simple and reliable empirical correlation for predicting the viscosities of heavy petroleum fractions is proposed, applicable to fractions with mid-boiling points from 80 to 550°C over a wide range of viscosities (0.4 to 260 mm² s⁻¹) and measurement temperatures (40 to 200°C). This correlation showed better accuracy in the prediction of heavy petroleum fraction viscosities than that of the most accurate and much more complicated predictive methods in the literature, since it gave an overall average absolute deviation of 6.5% when tested on 296 data for medium and heavy petroleum fractions.     

Characterization and compositional study of lighter fractions from coal-derived liquids

Synfuel fractions boiling in the range IBP-150 °C and 150–250 °C have been characterized. Individual component and hydrocarbon type distributions have been carried out quantitatively employing high resolution capillary gas chromatography and mass spectrometric techniques independently. More than 180 compounds including 60 olefins have been identified and quantified in the IBP-150 °C fraction only. A comparative study of hydrocarbon structures present in synfuel and crude oil fractions has been made and revealed that the cyclic character of coal-derived oils is due to predominance of hydroaromatics and cycloolefins rather than naphthenes alone. Moreover, for most of the homologous series of cyclic and aromatic structures, parent compounds are relatively more abundant in coal-derived oil than in natural crude petroleum and cracked petroleum fractions. The fractions have been evaluated for their suitability as gasoline/kerosene blending components in view of their estimated octane number and smoke point respectively.