The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
J. Murali Krishnan - One of the best experts on this subject based on the ideXlab platform.
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Influence of Crude Source on the Structural Indices of Short Residue
Transportation in Developing Economies, 2020Co-Authors: I. J. S. Sandeep, M. R. Nivitha, Sonal Maheshwari, J. Murali KrishnanAbstract:Production of bitumen for paving purposes is a complex operation at the refinery considering the variability in the Crude Source. At any instant of time, refineries process a blend of different Crudes, and the associated process parameters are varied in real time to maximize the throughput of the lighter ends. Such changes influence the chemical composition of the short residue. To quantify such changes, three different Crude Sources (Arab Mix, Kuwait, and Assam) were identified, and FTIR spectroscopy was used to characterize them. The variability across different Crudes and different short residue obtained from the respective Crudes and the relation between the Crude and the short residue were quantified in terms of the structural indices such as factor of aliphaticity, aromaticity index, carbonyl index, sulfoxide index, and condensation indices. It was seen that the structural indices from Crude oil to short residue were related and the relationship varied between the three different Crude Sources. Inter-relationships among different indices such as aliphaticity, aromaticity, branching, and condensation were observed, and the relationship among the Crude and short residue for these indices was reported.
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Characterization of Colloidal Stability of Blended Bitumen
Transportation Research, 2019Co-Authors: Uma Chakkoth, K. R. Krishna, M. Ramkumar, P. V. C. Rao, Parag Ravindran, J. Murali KrishnanAbstract:Air blowing and propane deasphalting (PDA) blending are the two processes used by the refineries in India to produce paving grade bitumen. In the PDA blending process, the proportion of the constituents (PDA pitch and flux) used in producing bitumen is decided based on the grade of bitumen to be processed. One main issue in the production of bitumen through the blending process is the compatibility of the two constituents used. If the constituents do not exhibit blend stability and compatibility at the microstructural level, it is expected that the binder may not exhibit the required performance even if it meets the appropriate binder specifications such as penetration at 25 \(^{\circ }\)C or viscosity at 60 \(^{\circ }\)C. This study reports one such attempt to check for the compatibility of the blended material using automated flocculation titrimeter. The current investigation primarily focuses on characterizing the influence of proportion of PDA pitch and type of Crude Source on the colloidal stability of bitumen. The refinery streams processed from a Crude oil mixture of Basrah Light (66%) and Murban (34%) was identified as the first Crude Source and a Crude oil mixture of AXL (80%), Basrah (10%) and Iran Mix (10%) was identified as the second Crude Source. Two different blend proportions of PDA pitch and flux from both the Crude Sources were made, and these were 75:25 and 80:20. These blend proportions were manufactured in a high shear rate blending facility. All the blends and the components were subjected to titrimetry at the unaged condition. It was seen that the compatibility of the material strongly depended on the proportion of the pitch as quantified by the asphalt state of peptization (P) value. The rheological properties of the blends were quantified by performance grading and frequency sweep tests. It was observed that blend samples with better compatibility also exhibited excellent rheological properties.
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Constant strain rate experiments and constitutive modeling for a class of bitumen
Mechanics of Time-Dependent Materials, 2012Co-Authors: Kommidi Santosh Reddy, S. Umakanthan, J. Murali KrishnanAbstract:The mechanical properties of bitumen vary with the nature of the Crude Source and the processing methods employed. To understand the role of the processing conditions played in the mechanical properties, bitumen samples derived from the same Crude Source but processed differently (blown and blended) are investigated. The samples are subjected to constant strain rate experiments in a parallel plate rheometer. The torque applied to realize the prescribed angular velocity for the top plate and the normal force applied to maintain the gap between the top and bottom plate are measured. It is found that when the top plate is held stationary, the time taken by the torque to be reduced by a certain percentage of its maximum value is different from the time taken by the normal force to decrease by the same percentage of its maximum value. Further, the time at which the maximum torque occurs is different from the time at which the maximum normal force occurs. Since the existing constitutive relations for bitumen cannot capture the difference in the relaxation times for the torque and normal force, a new rate type constitutive model, incorporating this response, is proposed. Although the blended and blown bitumen samples used in this study correspond to the same grade, the mechanical responses of the two samples are not the same. This is also reflected in the difference in the values of the material parameters in the model proposed. The differences in the mechanical properties between the differently processed bitumen samples increase further with aging. This has implications for the long-term performance of the pavement.
J A Bullin - One of the best experts on this subject based on the ideXlab platform.
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Reactivity of Asphalt Supercritical Fractions
Industrial & Engineering Chemistry Research, 1997Co-Authors: Meng Liu, Jay M. Chaffin, Richard R. Davison, Charles J. Glover, J A BullinAbstract:The reactivities of six supercritical fractions of asphalt SHRP AAF-1 were investigated in the context of their chemical composition. The supercritical fractions were obtained using pentane as the solvent. Each fraction was aged in a pressure oxygen vessel (POV) under seven conditions of temperature and pressure. As with whole asphalts, there is an initial rapid oxidation that slows to a constant rate. The oxidation rates for the constant rate region were measured at each of the conditions to determine the kinetic parameters of the fractions. Arrhenius plots were then constructed for the fractions to compare their reactivities. Variations in activation energy and reaction order were within experimental error. Results show that reactivity increases with fraction number for the supercritical fractions. The heavier fractions are more reactive not only because they contain more polar aromatics in terms of Corbett analysis fractions but also because the polar aromatics of the heavier fractions are larger in molecular size and are more reactive. Additionally, heavier fractions contain more asphaltenes that are larger in molecular size. Because for light fractions the reaction rates, and as previously shown the hardening rates, are very low and remain constant with oxidation, air blowing of some light fractions would more » be expected to produce an asphalt with a very low hardening rate. Data explicitly show that for petroleum fractions from the same Crude Source molecular size distribution is a good indicator of reactivity. This is not necessarily true for petroleum fractions from different Crude Sources, however. « less
Meng Liu - One of the best experts on this subject based on the ideXlab platform.
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Reactivity of Asphalt Supercritical Fractions
Industrial & Engineering Chemistry Research, 1997Co-Authors: Meng Liu, Jay M. Chaffin, Richard R. Davison, Charles J. Glover, J A BullinAbstract:The reactivities of six supercritical fractions of asphalt SHRP AAF-1 were investigated in the context of their chemical composition. The supercritical fractions were obtained using pentane as the solvent. Each fraction was aged in a pressure oxygen vessel (POV) under seven conditions of temperature and pressure. As with whole asphalts, there is an initial rapid oxidation that slows to a constant rate. The oxidation rates for the constant rate region were measured at each of the conditions to determine the kinetic parameters of the fractions. Arrhenius plots were then constructed for the fractions to compare their reactivities. Variations in activation energy and reaction order were within experimental error. Results show that reactivity increases with fraction number for the supercritical fractions. The heavier fractions are more reactive not only because they contain more polar aromatics in terms of Corbett analysis fractions but also because the polar aromatics of the heavier fractions are larger in molecular size and are more reactive. Additionally, heavier fractions contain more asphaltenes that are larger in molecular size. Because for light fractions the reaction rates, and as previously shown the hardening rates, are very low and remain constant with oxidation, air blowing of some light fractions would more » be expected to produce an asphalt with a very low hardening rate. Data explicitly show that for petroleum fractions from the same Crude Source molecular size distribution is a good indicator of reactivity. This is not necessarily true for petroleum fractions from different Crude Sources, however. « less
Charles J. Glover - One of the best experts on this subject based on the ideXlab platform.
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Reactivity of Asphalt Supercritical Fractions
Industrial & Engineering Chemistry Research, 1997Co-Authors: Meng Liu, Jay M. Chaffin, Richard R. Davison, Charles J. Glover, J A BullinAbstract:The reactivities of six supercritical fractions of asphalt SHRP AAF-1 were investigated in the context of their chemical composition. The supercritical fractions were obtained using pentane as the solvent. Each fraction was aged in a pressure oxygen vessel (POV) under seven conditions of temperature and pressure. As with whole asphalts, there is an initial rapid oxidation that slows to a constant rate. The oxidation rates for the constant rate region were measured at each of the conditions to determine the kinetic parameters of the fractions. Arrhenius plots were then constructed for the fractions to compare their reactivities. Variations in activation energy and reaction order were within experimental error. Results show that reactivity increases with fraction number for the supercritical fractions. The heavier fractions are more reactive not only because they contain more polar aromatics in terms of Corbett analysis fractions but also because the polar aromatics of the heavier fractions are larger in molecular size and are more reactive. Additionally, heavier fractions contain more asphaltenes that are larger in molecular size. Because for light fractions the reaction rates, and as previously shown the hardening rates, are very low and remain constant with oxidation, air blowing of some light fractions would more » be expected to produce an asphalt with a very low hardening rate. Data explicitly show that for petroleum fractions from the same Crude Source molecular size distribution is a good indicator of reactivity. This is not necessarily true for petroleum fractions from different Crude Sources, however. « less
Richard R. Davison - One of the best experts on this subject based on the ideXlab platform.
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Reactivity of Asphalt Supercritical Fractions
Industrial & Engineering Chemistry Research, 1997Co-Authors: Meng Liu, Jay M. Chaffin, Richard R. Davison, Charles J. Glover, J A BullinAbstract:The reactivities of six supercritical fractions of asphalt SHRP AAF-1 were investigated in the context of their chemical composition. The supercritical fractions were obtained using pentane as the solvent. Each fraction was aged in a pressure oxygen vessel (POV) under seven conditions of temperature and pressure. As with whole asphalts, there is an initial rapid oxidation that slows to a constant rate. The oxidation rates for the constant rate region were measured at each of the conditions to determine the kinetic parameters of the fractions. Arrhenius plots were then constructed for the fractions to compare their reactivities. Variations in activation energy and reaction order were within experimental error. Results show that reactivity increases with fraction number for the supercritical fractions. The heavier fractions are more reactive not only because they contain more polar aromatics in terms of Corbett analysis fractions but also because the polar aromatics of the heavier fractions are larger in molecular size and are more reactive. Additionally, heavier fractions contain more asphaltenes that are larger in molecular size. Because for light fractions the reaction rates, and as previously shown the hardening rates, are very low and remain constant with oxidation, air blowing of some light fractions would more » be expected to produce an asphalt with a very low hardening rate. Data explicitly show that for petroleum fractions from the same Crude Source molecular size distribution is a good indicator of reactivity. This is not necessarily true for petroleum fractions from different Crude Sources, however. « less