21 Search Results

Upgrading of heavy fossil fuels is normally done by hydrotreating in the presence of catalysts at 5 to 15 MPa pressure of hydrogen and 575 to 700 K. The efficient use of expensive hydrogen in this process is essential to the economic viability of alternative fuel sources (heavy petroleum, tar sands, shale oil, and the products of the liquefaction of coal). 2,3-Benzothiophene is widely used as a model compound in catalyst-comparison and kinetic studies of the hydrodesulfurization (HDS) mechanism. To perform a thermodynamic analysis of the 2,3-benzothiophene/hydrogen reaction network at the process temperatures, Gibbs energies of reaction at those high temperatures are required for the molecules involved. Measurements leading to the calculation of the ideal-gas thermodynamic properties for 2,3-benzothiophene are reported. Experimental methods included adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). The critical temperature and critical density were determined with the d.s.c., and the critical pressure was derived. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for selected temperatures between 260 K and 750 K. These values were derived by combining the reported measurements with values published previously for the enthalpy of combustion, the enthalpy of fusion, and the absolute entropy and enthalpy of the liquid at the triple-point temperature. Measured and derived quantities were compared with available literature values. 55 refs., 6 figs., 13 tabs.

Catalytic hydrodenitrogenation (HDN) is a key step in upgrading processes for conversion of heavy petroleum, shale oil, tar sands, and the products of the liquefaction of coal to economically viable products. This research program provides accurate experimental thermochemical and thermophysical properties for key organic nitrogen-containing compounds present in the range of alternative feedstocks, and applies the experimental information to thermodynamic analyses of key HDN reaction networks. This report is the first in a series that will lead to an analysis of a three-ring HDN system; the carbazole/hydrogen reaction network. 2-Aminobiphenyl is the initial intermediate in the HDN pathway for carbazole, which consumes the least hydrogen possible. Measurements leading to the calculation of the ideal-gas thermodynamic properties for 2-aminobiphenyl are reported. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for selected temperatures between 298.15 K and 820 K. The critical temperature and critical density were determined for 2-aminobiphenyl with the d.s.c., and the critical pressure was derived. The Gibbs energies of formation are used in thermodynamic calculations to compare the feasibility of the initial hydrogenolysis step in the carbazole/H{sub 2} network with that of its hydrocarbon and oxygen-containing analogous; i.e., fluorene/H{sub 2} and dibenzofuran/H{sub 2}. Results of the thermodynamic calculations are compared with those of batch-reaction studies reported in the literature. 57 refs., 8 figs., 18 tabs.

Before steamflooding became an oil field practice, static chokes were used extensively and satisfactorily on gas wells to control the gas flow rate. The flow-rate equations and critical-pressure information were developed for gas, a single-phase fluid. Most steam used in steam EOR projects is a wet steam that is a two-phase liquid. The flow rate and pressure of the critical flow of wet steam are not fully understood. This paper investigates the critical-flow rate and critical-pressure ratio of the wet steam by use of analytical models and experimental data and establishes empirical correlations for the critical flow rate and critical pressure. Focusing on practical oil field applications, this study covers the critical flow of steam with steam pressures ranging from 50 to 2,000 psia (0.3 to 13.8 MPa) and steam quality ranging from 10 to 100%.

This model uses the unsteady-state line source and sink solution (in the form of gas pseudo-pressure) to the real gas diffusivity equations and flow along pathlines to simulate flow and pressure in the reservoir. The conductivity ratio method is used to adjust reservoir pressures for the effect of two phases. The properties of vapor and liquid phases are obtained via vapor liquid equilibrium calculations that are done using equilibrium coefficients. These equilibrium coefficients are computed from empirical correlations as functions of pressure, temperature and convergence pressure. In addition to the normal results obtained from similar simulators, this model calculates the physical properties of the mixture. These properties include critical temperature and pressure, the dewpoint pressure at the critical temperature, and the cricondentherm temperature and the dewpoint pressure at this temperature. Also, the upper and lower dewpoint pressures at reservoir temperature are given by the program if the mixture is a gas condensate system. This model serves as a new general type of primary recovery predictor for the pressure depletion recovery process for gas condensate reservoirs. This program was built to run on a personal computer and can be applied to reservoirs of any shape or size and containing any number of wells. Favorable results were obtained when compared to the analytical solution for a well in the center of circular reservoir that was homogeneous, isotropic, and of constant thickness. Comparison of this model with a commercial finite-difference simulator, ECLIPS-300, that uses a cubic equation of state (Peng-Robinson) showed that results from our model match results from ECLIPS-300 model if they both use the same PVT data.

A method of fractionating a mixture containing high boiling carbonaceous material and normally solid mineral matter includes processing with a plurality of different supercritical solvents. The mixture is treated with a first solvent of high critical temperature and solvent capacity to extract a large fraction as solute. The solute is released as liquid from solvent and successively treated with other supercritical solvents of different critical values to extract fractions of differing properties. Fractionation can be supplemented by solute reflux over a temperature gradient, pressure let down in steps and extractions at varying temperature and pressure values.

Thermal solution of an aromatic Sunbury oil shale kerogen was studied using three solvents: toluene above its critical temperature, methylcyclohexane above its critical temperature, and tetralin at subcritical temperatures. 66 thermal solutions tests were conducted which included 29 isothermal tests using all 3 solvents and 37 linear-heating tests using tetralin. Maximum kerogen conversions to soluble products, as determined by low temperature ash analyses, were 49% for extraction with toluene, 58% for extraction with methylcyclohexane, and 80% for extraction with tetralin. The bulk of the product recovery by solvent extraction was observed to occur between 325 and 375/sup 0/C. In this region the yield increased from between 9% to 22% of maximum yield up to 91% to 100% of maximum yield. Analyses of the yields and elemental composition of the spent shale residues from the linear-heating tests suggested a two-step kerogen-to-bitumen decomposition mechanism. This mechanism consists of parent kerogen decomposing to a single intermediate with the release of water, sulfur compounds, and minor amounts of hydrocarbons, followed by decomposition of the intermediate to a final insoluble residue with the accompanying formation of soluble bitumen. Kinetic rate analyses of the test data based on this mechanism permitted determination of rate parameters which successfully predicted the experimental yields from the linear-heating tests and some of the isothermal tests. The value for the activation energy was determined to be 53.9 Kcal/mole with an associated pre-exponential factor of 2.6 x 10/sup 16/ min./sup -1/. Stoichiometric conversion to the intermediate was determined to be 93% of the parent kerogen, while stoichiometric conversion to the final residue was determined to be 25% of the parent kerogen.

Measurements have been made on the chemical and physical properties of two oil shales designated as interim reference oil shales by the Department of Energy. One oil shale is a Green River Formation, Parachute Creek Member, Mahogany Zone Colorado oil shale from the Anvil Points mine and the other is a Clegg Creek Member, New Albany shale from Kentucky. Material balance Fischer assays, kerogen concentrates, carbon aromaticities, thermal properties, and bulk mineralogic properties have been determined for the oil shales. The measured properties of the interim reference shales are comparable to results obtained from previous studies on similar shales. The western interim reference shale has a low carbon aromaticity, high Fischer assay conversion to oil, and a dominant carbonate mineralogy. The eastern interim reference shale has a high carbon aromaticity, low Fischer assay conversion to oil, and a dominant silicate mineralogy. Chemical and physical properties, including ASTM distillations, have been determined for shale oils produced from the interim reference shales. The distillation data were used in conjunction with API correlations to calculate a large number of shale oil properties that are required for computer models such as ASPEN. The experimental determination of many of the shale oil properties was beyond the scope of this study. Therefore, direct comparison between calculated and measured values of many properties could not be made. However, molecular weights of the shale oils were measured. In this case, there was poor agreement between measured molecular weights and those calculated from API and other published correlations. 23 refs., 12 figs., 15 tabs.

Three new predictive equations for cetane number have been developed. Each of these equations is shown to be superior to the current cetane index equation (ASTM D976-80) for a large fuel data base. One of the equations has the further advantage of requiring only one property measurement (aniline point). The equations were developed from a detailed analysis of functional relationships between measured cetane number (ASTM D613-84) and commonly measured physical properties of diesel fuels; aniline point, density, and distillation temperatures. The data base for this study totaled 1229 fuels, including commercial fuels from the U.S. Canada, Europe, and Japan; synthetic fuels derived from tar sands, shale, and coal; and a diversity of research fuels blended from straight-run and cracked stocks. The equations were optimized using data-fitting techniques which account for bias amongst the various data sources and for measurement errors in both the dependent and independent variables.

Three new predictive equations for cetane number have been developed. Each of these equations is shown to be superior to the current cetane index equation (ASTM D976-80) for a large fuel data base. One of the equations has the further advantage of requiring only one property measurement (aniline point). The equations were developed from a detailed analysis of functional relationships between measured cetane number (ASTM D613-84) and commonly measured physical properties of diesel fuels; aniline point, density, and distillation temperatures. The data base for this study totaled 1229 fuels, including commercial fuels from the U.S. Canada, Europe, and Japan; synthetic fuels derived from tar sands, shale, and coal; and a diversity of research fuels blended from straight-run and cracked stocks. The equations were optimized using data-fitting techniques which account for bias amongst the various data sources and for measurement errors in both the dependent and independent variables.

Binary interaction parameter k/sub ij/ was correlated as functions of molecular weight and boiling point for hydrocarbon, nonhydrocarbon, and mixed binaries. The k/sub ij/-functions yield the value of zero for k/sub ij/ when i = j are extended to binaries involving heptanes-plus pseudo-component. These functions provide new techniques for establishing the k/sub ij/-coefficient in the equation-of-state mixing rules without resorting to arbitrary values, as is commonly done. Critical pressures, critical temperatures, and acentric factor correlations of heavy fractions developed from petroleum fractions and pure components are based on a new characterization scheme which uses molecular weight, boiling point, specific gravity, and refractive index. The use of this non-iterative scheme for correlating paraffinic, naphthenic, and aromatic categories of hydrocarbons has never before been achieved. A van der Walls model based solely upon pure component critical data is developed for viscosity. Mixing rules are proposed and the extension of these rules to reservoir oils viscosity prediction was generally within +/-6% of the experimental values. A generalized cubic equation of state (EOS) is developed as functions of coefficients ..cap alpha.. and ..beta.. in the attractive pressure term and the limiting critical volume b/V/sub c/. From this generalized model, all the patterns of the previously published cubic equations of state are unfolded. The versatility of this model was demonstrated by constructing two-and four-parameters EOS'.