Viscosity Model for CO-Noble Gas Mixtures at Atmospheric Conditions

Abstract

We have presented an empirical model for predicting the viscosity of binary mixtures of gases, based on our previous correlation for natural gas mixtures (Miadonye and Clyburn, 2003 Miadonye, A. and Clyburn, W. 2003. Modelling the Viscosity of Natural Gas Mixtures, Computational Methods and Experimental Measurements, Edited by: Esteve. Southhampton, , UK: WIT Press.  [Google Scholar]). New parameters were derived for binary mixtures of carbon monoxide-noble gases and for carbon monoxide-nitrogen gases, for temperatures from 0–1000°C. The model was validated with the Chapman-Enskog equation for gas mixtures, with and without length scaling factor. For five equimolar and eight non-equimolar mixtures of gases at temperatures from 0–1000°C, the model gave an excellent viscosity prediction with an overall average absolute deviation of 0.45%. The model is simple to incorporate in design and simulation packages, and more accurate than any correlation currently used for estimating the viscosities of gas mixtures.     

Viscosity Model for Petroleum Gases

Abstract

The production processes for petroleum gases employ a broad range of simulation packages to reduce capital, time, and cost associated with actual recovery and pipeline transportation. Viscosity model is an important component of these packages. In this work, we have presented an empirical model for predicting the viscosity of petroleum gases, developed from the three-parameter Yaws equation. New constants were derived for various petroleum gases, as well as for gaseous carbon dioxide. Results obtained with the new model were compared with the viscosity predictions from the Yaws model, and the Miadonye and Clyburn correlation. For four petroleum gases and carbon dioxide at temperatures of 110 K to 1,500 K, the model gave an excellent viscosity prediction with overall average absolute deviations of 0.34% and 0.98%, respectively. The model is simple to incorporate into design and simulation packages, and more accurate than any correlation currently used in petroleum industry for predicting the viscosities of petroleum gases.     

Viscosity Model for Petroleum Gases

The production processes for petroleum gases employ a broad range of simulation packages to reduce capital, time, and cost associated with actual recovery and pipeline transportation. Viscosity model is an important component of these packages. In this work, we have presented an empirical model for predicting the viscosity of petroleum gases, developed from the three-parameter Yaws equation. New constants were derived for various petroleum gases, as well as for gaseous carbon dioxide. Results obtained with the new model were compared with the viscosity predictions from the Yaws model, and the Miadonye and Clyburn correlation. For four petroleum gases and carbon dioxide at temperatures of 110 K to 1,500 K, the model gave an excellent viscosity prediction with overall average absolute deviations of 0.34% and 0.98%, respectively. The model is simple to incorporate into design and simulation packages, and more accurate than any correlation currently used in petroleum industry for predicting the viscosities of petroleum gases.     

基于PR状态方程的粘度模型

基于p-v-T和T-μ-p图形的相似性。结合两参数Peng-Robison状态方程,建立了一个能够同时预测流体气、液相粘度的统一模型。该模型的特点是能够同时描述气、液相及超临界流体的粘度随温度、压力和组成的变化,并能够连续通过临界点。在宽广的温度、压力范围内,对22种烷烃及二氧化碳、氮气共计4250个数据点的粘度进行了计算,绝对平均误差为7.01%;通过引入vanderWals单流体混合规则,将PR粘度模型应用于明确烃类混合物及油气藏流体粘度的计算。三个二元烃类混合物2441个数据点的绝对平均误差为15.71%;9种天然气及22种油藏原油粘度计算值的绝对平均误差分别为9.8%和13.99%,计算结果优于现有的油气藏流体粘度模型。     

Rheology of Middle Distillate. I. Role of Composition

The rheological behavior of middle distillate (250-375°C) fraction, obtained from the waxy Bombay-High Off-shore crude oil, and its five narrow sub-fractions of 25°C interval each, i.e., Fr 1 (250-275°C), Fr 2 (275-300°C), Fr 3 (300-325°C), Fr 4 (325-350°C), and Fr 5 (350-375°C), have been studied below their ASTM pour point temperatures. The rheograms (the shear stress vs. rate of shear) of the fraction and sub-fractions, at various temperatures below their pour points, are recorded on a Haake RV-12 Co-axial Rota Viscometer fitted with a NV sensor and a temperature programmer (PG-20) and attached with a programmed heating/cooling system. From these rheograms the flow parameters like plastic viscosity, apparent viscosity, and yield stress are obtained and their variations with temperature and shear rate have been studied in terms of compositions of the fraction/sub-fractions. These results might be useful in devising methodology for overcoming the wax separation phenomenon from middle distillates at low temperatures.     

KINEMATIC VISCOSITY-TEMPERATURE BEHAVIOR OF HEAVY TBP-FRACTIONS (455°C+) OF ARABIAN CRUDE OILS

A generalized kinematic viscosity-temperature correlation for undefined liquid heavy petroleum fractions has been developed to represent the data for a wide range of temperature from 100°C to 200°C. The correlation is based on the experimental kinematic viscosity data of true boiling point fractions of four Arabian crude oils. The characterization property required for estimation is 50% boiling point. The proposed correlation fits the experimental data with an overall absolute error of 6.1%. Experimental measurements of kinematic viscosity of heavy true boiling point fractions of Arabian crude oils were also obtained in order to develop the proposed correlation.     

ESTIMATING TEMPERATURE AND PRESSURE EFFECTS ON VISCOSITY OF SASKATCHEWAN HEAVY OILS

Predictions for viscosity of Saskatchewan heavy oils are validated with experimental data at various temperatures and a wide range of pressures. Comparisons of predictions made with a single measured value and curve-fit value both at 30°C and 0 MPag pressure showed that results obtained with the later were in better agreement with experimental values; with overall average absolute deviations of 6.9%and 2.9% respectively

The results demonstrated that extreme care is essential in measuring viscosity at the reference temperature if accurate prediction is to be achieved with the correlation; and furthermore that the correlation can successfully predict heavy oils viscosity.     

VISCOSITY OF WATER IN OIL EMULSIONS

Increase in water cut in oil fields generally calls for an increase in the capacity of transport pipelines. Proper design and operation of the latter requires good knowledge of the thermophysical properties of flow resistance of crude-oil water mixtures. An experimental program aimed at measurements of oil-water emulsion viscosity for water cuts prior to the inversion point was conducted.

The present work reports on measurements of Nimr crude oil-water mixtures viscosity for different water cuts and a typical range of temperatures representative of field conditions (20°-50°C). Three mixing intensities of 10⁶, 5×10⁶ and 15×10⁶ erg/cm-sec generated by a dynamic coalescer and directly relevant to field conditions were used.

The results suggest that the inversion point occurs around a value of water cut of 35%. Both Newtonian and non-Newtonian (pseudo-plastic) behaviour were observed, and the ASTM viscosity model is found to be applicable to the emulsions. The effect of the mixing intensity on the resulting emulsion viscosity was found to be important at low temperatures and decreased at high temperatures. The experimental data fitted the available correlations in the literature.     

液体混合物的粘度方程

根据Ｅｙｒｉｎｇ纯液体粘度理论，引入胞腔理论中的局部组成概念，提出了一个液体混合物粘度方程。该方程应用于３４个体系共４９套二元系粘度数据的关联和１９个体系共２５套三元系粘度数据的预测，其中包括非极性、极性和含水体系。计算表明，对各类体系，该方程均得到令人满意的关联或预测结果。     

VISCOSITY OF BITUMEN-CRUMB RUBBER BLEND (NEW PAVING MATERIAL)

The feasibility of blending scrap tire rubber with Asphalt Ridge and Circle Cliffs (Utah, USA) tar sand bitumens was studied. Viscosity of the blended mixtures was analyzed as a function of composition, and coprocessing variables including processing temperature and time. Coprocessing of tar sand bitumens with crumb rubber at elevated temperatures has been shown to increase the viscosity of the bitumens with the exception of the bitumen-rubber sample prepared at 380°C. Optimum viscosity behavior was exhibited for an oil-extended bitumen blended with crumb rubber at 200°C for 0.5 hours. The viscosity of the bitumen-rubber blend prepared under these conditions met ASTM specifications of a viscosity-graded AC-30 asphalt binder. Viscosity increase was most noticeable at low temperature, providing the benefit of high viscosity at pavement temperatures experienced during summer months without concession of processability at pavement construction temperatures. A difference in viscosity was observed between bitumen modified with whole-tire crumb and tread-rubber crumb, due to the compositional differences that exist between the two materials.     

VISCOSITY ESTIMATION FOR BITUMEN-DILUENT MIXTURES

A generalized viscosity correlation has been used to predict the viscosity-temperature relationship of bitumen mixed with various proportions of diluents such as GCOS synthetic crude, mobil solvent and naphtha. The results showed that the correlation can accurately predict the viscosities of bitumen-diluent mixtures based on a single viscosity measurement at 30°C and one atmosphere. For 300 experimental points, the correlation yielded an overall average absolute deviation between predicted and experimental values of 8.7%. It is found that the correlation gave high percent errors for mixtures with high disparity in viscosity between bitumen and diluent.     

THERMOCHEMICAL CONVERSION OF BIOMASS TO CHARCOAL: COLLECTION AND CHARACTERIZATION OF BYPRODUCT

Thermochemical conversion of biomass was carried out using a laboratory pyrolyzer at temperatures of 280-500°C. The charcoal yield varied from 72 and 40% respectively and the tar yield at the above two temperatures varied from 2.0 and 4.2%. The structure of charcoal and bio-oil was determined by infrared and nuclear magnetic resonance. The non-condensible gases were analyzed by gas chromatography.     

VISCOSITY MODELLING OF AMERICAN CRUDE OIL FRACTIONS

The applicability of a recently proposed viscosity-temperature correlation for conventional crude oil, based on a single viscosity measurement, is extended to new data on light crude oil fractions. The correlation yielded predictions with an overall average absolute deviation of 0.86% from experimental values for 32 data sets consisting of 2 67 individual measurements.

For the lighter fractions, with viscosity below 3 cSt at 30°C, the correlation is shown to be capable of predicting the viscosity with an average absolute deviation of less than 1%. The prediction was based on a single viscosity point at 37.78°C (100°F) estimated by curve-fit method for each data set.     

Thermal Hydrocracking Kinetics of Chinese Gudao Vacuum Residue

The thermal hydrocracking kinetics of Chinese Gudao vacuum residue was studied in a batch autoclave reactor. The temperature ranged in 390-435°C and the initial hydrogen pressure was 7.0 MPa at 20°C. Ammonium phosphomolybdate (APM) in its dispersed phase was the catalyst. The reaction products, gas, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and coke, were separated during and after experiments, and their yields vs. reaction time were obtained, for four reaction temperatures: 390, 405, 420, and 435°C. The activation energy was calculated from a traditional kinetic model to be 218.6 kJ/mol. A new kinetic model was proposed in this work that allows for the calculation of activation energy with a minimum number of three tests, each at a different temperature. This is comparable to the traditional model which requires a minimum of 12 tests; a minimum of four tests for one temperature and a minimum of three temperatures. The activation energy calculated from the new model with four tests is 229.6 kJ/mol, only 5% greater than that obtained from the traditional model. The reaction rate constants obtained from this model are also consistent with those from the traditional model.     

Viscosity and Density Correlations for Hydrocarbon Gases and Pure and Impure Gas Mixtures

Abstract

In this work, newly developed correlations for hydrocarbon gas viscosity and density are presented. The models were built and tested using a large database of experimental measurements collected through extensive literature search. The database covers gas composition, viscosity, density, temperature, pressure, pseudoreduced pressure and temperature and compressibility factor for different gases, and pure and impure gas mixtures containing high amount of pentane plus and small concentration of nonhydrocarbon components. Gas viscosity and gas density models were built with 800 randomly selected data points extracted from the large database. The models were developed using the Alternating Conditional Expectations (ACE) algorithm. The models' accuracy was validated using the rest of the database, and their efficiency was tested against some commonly used correlations. The developed models seemed very efficient and they accurately predicted the experimental viscosity and density measurements, overcoming several constraints limiting the other correlations' accuracy with average absolute errors of 3.95% and 4.93% for the gas viscosity and gas density models, respectively. Sensitivity analysis of the proposed gas viscosity model indicated the positive impact of density and pseudoreduced temperature and the trivial impact of pseudoreduced pressure. The gas density model was found to be sensitive to all input parameters of pseudoreduced temperature, apparent molecular weight, and pseudoreduced pressure listed on the order of their impact. Negative impact was predicted for reduced temperature, whereas positive ones werenoticed for the pseudoreduced pressure and gas apparent molecular weight.     

PYROLYSIS OF SUNNYSIDE (UTAH) TAR SAND: CHARACTERIZATION OF VOLATILE COMPOUND EVOLUTION

Sunnyside (Utah) tar sand was subjected to programmed temperature pyrolysis and the volatile products were detected by tandem on-line mass spectrometry (MS/MS) in real time analyses. A heating rate of 4°C/min from room temperature to 900°C was employed.

Evolution of hydrogen, light hydrocarbons, nitrogen-, sulfur-, and oxygen-containing compounds was monitored by MS or MS/MS detection. Evolution of volatile organic compounds occurred in two regimes: 1) low temperature (maximum evolution at 150 to 175°C), corresponding to entrained organics, and 2) high temperature (maximum evolution at 440 to 460°C), corresponding to cracking of large organic components. Alkanes and alkenes of two carbons and higher had temperatures of maximum evolution at approximately 440°C, and methane at approximately 474°C. Aromatic hydrocarbons had temperatures of maximum evolution slightly higher, at approximately 450° C. Some nitrogen-, sulfur-, and oxygen-'ccntaining compounds were also detected in the volatile products.

Comparing the Sunnyside pyrolysis to the pyrolysis of other domestic tar sands indicated the following for hydrocarbon evolution: 1) the evolution of entrained organics relative to the total evolution was much less for Sunnyside tar sand, 2) the temperatures of maximum evolution of hydrocarbons due t o cracking reactions were slightly lower, and 3) the temperatures of maximum evolution for benzene and toluene are slightly higher than observed for other tar sands.

In general, the noncondensible gases, H₂, CO, and CO₂, exhibited evolution associated with hydrocarbon cracking reactions, and high temperature evolution associated with mineral decomposition, the water-gas shift reaction, and gasification reactions. Pyrolysis yields were dominated by the evolution of carbon oxides and water. The CO₂ primarily appeared t o cane from the decomposition of carbonate minerals. Compared t o other domestic tar sands, the gas evolution reflected more mineral decomposition character for Sunnyside tar sand.     

ARAB LIGHT CRUDE STUDY FOCUSES ON KINEMATIC VISCOSITY

Arab light crude oil has been characterized in terms of API gravity, total sulfur content, Reid vapor pressure, ash content, heating value, salt content, viscosity SUS, vanadium content as V₂O₅, pour point and analyses of various metals. The crude oil was fractionated into six true boiling point (TBP) fractions (IBP-95°C, 95-205°C, 205-260°C, 260-345°C, 345-455°C and 455°C+). These fractions were characterized in terms of API gravity, total sulfur, H₂S, mercaptan contents, molecular weight, elemental analyses for total carbon, hydrogen and nitrogen, and analyses of various metals. The kinematic viscosity data have been obtained for 95°C+ TBP fractions for a wide range of temperature up to 200°C.     

CHARACTERIZATION OF ASPHALTENE PARTICLES BY LIGHT SCATTERING AND ELECTROPHORESIS

The solubility of asphaltenes in heptane/toluene mixtures was studied at several temperatures. A significant increment in asphaltene solubility was observed when the temperature increases from 0°C to 20°C and a moderate increase when the temperature rose from 20°C to 50°C. These results indicate that asphaltenes behave as a higher consulate temperature system, similar to nonpolar waxes. Examined by photon correlation spectroscopy, diameters from the particles formed a range between 125 and 400 nm, depending on the amount of non-solvent (n-heptane) used for the precipitation process and the initial concentration of asphaltenes. The particles presented a small positive surface potential that was not altered by the addition of resins.     

Effect of Molecular Weight on Thermal Conductivity of Gases

A new formula has been developed to estimate thermal conductivity of hydrocarbon gases dependent on molecular weight of the range 20-100 and under temperatures ranging between 0 and 400°F. In this work an introduction of the available observed data develops a new correlation for the effect of molecular weight on the predication of thermal conductivity of gases.     

Physical Properties of Aqueous N-Methyl Pyrrolidone at Different Temperatures

Many physical properties of aqueous N-Methyl pyrrolidone mixtures were determined for molar fraction X_NMP = 0.02, 0.05, 0.125, 0.32, 0.37 at different temperatures ranging from 15-65°C. From the result we noticed that the viscosity coefficient was increased with increasing the molar fraction X_NMP and reached a maximum value at X_NMP = 0.25-0.37, and decreased with temperature. We observed the same relationship of the thermodynamic properties for the mixture at different temperatures and for excess activation function was positive. They reached maximum value at the X_NMP = 0.25-0.37. The same relationship was observed for excess dielectric constant. The results were explained according to hydrogen bonding effects and dipole-dipole interactions. This binding is stronger than binding between water molecules which may be let to form a complex at the molal fraction ratio 2:1 of water-NMP solution. We noticed that an increase in temperature may be let to tighten the interaction between water and NMP.