H. U. Khan

Wax deposition of Bombay high crude oil under flowing conditions

Abstract The wax deposition rate of Bombay high crude oil under flowing conditions in a horizontal pipe was studied at different flow rates and at different temperature differentials between the oil and the cold surface. The deposition was found to increase asymptotically with time and reach a final fluctuating value. The time to obtain equilibrium deposition varied with test conditions. A mathematical equation correlating the flow rate and temperature differential with the equilibrium deposition was also developed.

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.

Determination of average carbon number of petroleum waxes by X-ray diffraction

Eight petroleum waxes, both paraffin as well as microcrystalline, have been analysed by X-ray diffraction. The average carbon number has been estimated by the long-range ordering observed in the diffractograms of these waxes. The average carbon number has also been determined following the standard gas chromatographic (GC) method. The results obtained by X-ray diffractometry compare well with those obtained by the GC method. The former method also permits determination of the average carbon number of high melting point waxes, which is otherwise difficult using GC.

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.

Study of Phase Transition in Hard Microcrystalline Waxes and Wax Blends by Differential Scanning Calorimetry

Abstract Phase transition temperature and associated energies in hard high melting microcrystalline waxes and its various blend with paraffin wax (melting range from 60 to 97°C) have been determined by DSC in both heating and cooling mode. The dependence of these on the composition and properties of waxes have been analyzed. The solid liquid transition temperature obtained by DSC has been compared with ASTM drop melting point of these wax samples. The present study has demonstrated that DSC can be of great use in identifying whether the wax sample is blend of different waxes or not.

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.

Influence of n-alkanes on the cold flow properties of their solution in different solvent systems

Abstract The effect of composition of n -alkanes on the cloud and pour point of their solution in different solvent systems was investigated and a method of identifying the key components responsible for the adverse flow behaviour exhibited by petroleum fluids at low temperature was developed. It was observed that in a given solvent matrix the influence of the composition of the n -alkanes predominates over that of their concentration.

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.