S. P. Nautiyal

SOLUBILISED WAXES AND THEIR INFLUENCE ON THE FLOW PROPERTIES OF LUBE OIL BASE STOCKS

ABSTRACT The physico-chemical properties of Lubricating oil base stocks (LOBS) are generally influenced by the type/nature and concentration of solubilised waxes present in them. Detailed composition of the solubilised waxes, saturates and aromatics present in LOBS and its distillate fractions has been sludied. Further the influence of these solubilised waxes and as well of saturates/aromatics on the flow properties particularly pour point, viscosity and viscosity temperature relationship of LOBS sample and its distillate fractions have been investigated. The response of a commercial pour point depressant additive with varying composition of solubilised waxes in lube oil base stock sample has also been studied.

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

ABSTRACT The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With...

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART II EFFECT OF WAX COMPOSITION AND CONCENTRATION ON THE DEW AXED CRUDE OILS WITH / WITHOUT ADDITIVES

ABSTRACT In this part of the work the effect of wax concentrations on the rheologica! properties of the dewaxed Duliajan (Assam) and Lingaia crude oils have been studied. The dewaxing of the crude oil was done by removing n-paraffins from the crude oil by urea adduction. The urea adducted n-paraffins concentrate-the wax- was characterized by its carbon number distribution. The urea non adducted oil portion - the denormalized crude oil (DNO)- was characterized for its pour point. The wax in different concentration was then added in the DNO and the change in the rheological properties like pour point, yield stress and plastic viscosity were studied using a Haake Rota Viscometer. The effect of carbon number distribution, i.e. the composition of the wax, on these rheological properties was also investigated. Four different commercial pour point depressanl additives have been used to study their effects on the pour point, yield stress and plastic viscosity of the reconstituted (wax mixed DNO) crude oils. From ...

Composition and Properties of Some Petroleum Waxes

Abstract Structural composition of paraffin waxes and soft wax fraction derived from microcrystalline wax were determined. Waxes were fractionated by multistage solvent crystallization at different temperatures. The n-alkane components of the waxes were separated by urea adduction. The average structural parameters of parent waxes, their fractions, and urea adductables were estimated by 1h and 13C NMR spectroscopy. The thermal parameters viz. phase transition temperature and the associated energy during phase transitions were determined by using DSC and correlated with the penetration temperature behavior of waxes. The carbon number distribution determined by GC for these waxes and their n-alkane components were also correlated with physical properties and thermal parameters.

STRUCTURAL CHARACTERIZATION OF SOLID n-PARAFFIN COMPONENTS DERIVED FROM MUKTA CRUDE OIL

ABSTRACT The total solid paraffins (boiling 270°C+) separated from Mukta crude by urea adduction and its narrow fractions were analysed for their structural composition by proton NMR, infrared spectroscopy and gas chromatography. It has been observed that CH2/CH3 ratio in these samples varies from 7·9 to 13·8 while their average carbon number ranges from 17 to 29·6. The CH2/CH3 ratio and chain length of paraffins increases with increase in boiling range of the fractions.

Crystal Structure of n-Paraffin Concentrates of Crude Oils

Abstract The n-alkanes are the major constituents of paraffin waxes, which adversely affect the cold flow properties of crude oils and their fractions (gel formation). The n-alkanes crystallize out from the solution as the temperature is lowered. The knowledge of the structure of crystals is essential to understand the gel formation behavior of crude oil. n-Paraffin concentrates were extracted from six Indian crude oils. One particular n-paraffin concentrate was fractionated into smaller fractions by distillation. The crystal structure of these n-paraffin concentrates were determined by X-ray diffraction and correlated with the distribution of the carbon number present in them. It was observed that the crystal structures of these n-paraffin concentrates is greatly influenced by the carbon number distribution and the presence of amorphous content.

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.

PARAFFIN DEPOSITION AND VISCOSITY TEMPERATURE BEHAVIOUR OF ASSAM CRUDE OIL

ABSTRACT The rate of paraffin deposition at equilibrium under different flowing conditions, viz, flow rate, oil and cold surface temperatures, and also viscosity temperature behaviour of Assam crude having wax content 11·0 % wt. and pour point 30°C has been studied. The effect of various diluents viz commercial kerosene and diesel oil on paraffin deposition and viscosity temperature behaviour have been determined. Deposition data has also been quantified in the form of a regression equation. It has been observed that added solvent significantly effect the paraffin deposition and viscosity temperature behaviour.

IR and HNMR Analysis of Asphaltic Materials Present in Some Indian Crude Oils of Gujarat Region

Abstract The structure and composition of asphaltic materials present in three crude oils produced from three reservoirs situated at Viraj, North Kadi, and Santhol in north Gujarat region in western India have been studied using IR and HNMR spectroscopy. The asphaltenic substances were obtained by Soxhlet extraction of the 200°C+ residue of each crude oil with n-pentane, n-heptane, petroleum ether (40–60°C), and ethyl acetate, following the standard IP 143/78 method. The variations in chemical nature and composition of all solvent-insoluble asphaltenic components have been discussed. All insolubles constitute mainly highly substituted aromatics having ether linkages, ketone and pyrrolic N-H functions, and large number of methyl and methylene groups in alkyl chain substituents.

ROLE OF COMPOSITION ON THE VISCOSITY AND SHEAR STRESS TEMPERATURE BEHAVIOUR OF SOME LUBE OIL BASE STOCKS

Lubricating oil base stocks differ greatly in their chemical composition and consequently in their physical properties and applications. Influence of waxes and various hydrocarbon type constituents viz saturates and aromatic components on the viscosity and shear stress as a function of temperature in different lube oil base stocks has been studied in the present paper.