Simulated Vacuum Residue

Conradson coke residue in the simulated vacuum residue (%) residue at 800 °C in the simulated vacuum residue (%) residue in the extrapolated point of inflexion of the TGA curve in the simulated vacuum residue (%)... 

The Conradson coke residue in the simulated vacuum residue ((CCR/SVR) 100) for the vacuum residues and bitumens has a mean value x2l.6%( y= 7.01% relative). For the atmospheric residues the mean amounts to x = 13.8 % ( + y = 8.7 % relative). The products from conversion processes (samples 19, 20, and 22) have extremely high values demonstrating that they have been distilled exhaustively, whereas the distillate of the residue of a cat-cracker, sample 25, exhibits the extremely low value of 4.4 %. 

The relation of the residue at the inflexion point of the TGA curve, to the simulated vacuum residue (G /SVR) 100 for the group of the vacuum residues and bitumens shows widely differing values for blown (partly oxidized) products (samples 6, 7, 10, and 11). Statistical treatment (G /SVR) 100 for samples 1-13 give a mean x = 25.1 % with the very large coefficient of variation V = 20.86 % (relative). When the blown products are excluded there is a considerably smaller scattering of results ... 

Considering the temperature limits in use in refinery processes a value of 100 % simulated atmospheric residue, SAR, is found in most of the samples of investigation. By this definition, the four atmospheric residues have not been fully distilled. The simulated vacuum residue, SVR, shows how far the samples are distilled. Since the SVR = 100 -AG300, exhibits higher values than the non-distiUable portion of the sample ND = 100 -AG400, the values of that part of the sample which is crackable in practice, PCR, exceed the more theoretical values, CR. The ratio PCR/SVR does not give a clear distinction of distillation residues from conversion products than it is possible using the ratio CR/ ND. 

The relation of the different index numbers characterizing the coke residue to the simulated vacuum residue, SVR, does give useful results. The relation of the Conradson coke residue CCR to SVR results in ratios between 10.0 and 23.4 for vacuum residues and bitumens to ratios from 12.2 to 14.8 for atmospheric residues and the ratio for residues from conversion processes gives values of over 27 up to 43. 

The relation of R800 to the simulated vacuum residue SVR is similar. Since the values of R800 are lower than the corresponding values of CCR and G, the ratio R800/SVR generally has lower values than both the other index numbers (CCR/SVR and G / SVR). 

Finally, other methods are used to obtain simulated distillation by gas phase chromatography for atmospheric or vacuum residues. For these cases, some of the sample components can not elute and an internal standard is added to the sample in order to obtain this quantity with precision. 

To assess the effect of pretreatment on early coke formation, two sets of runs, R06/ R08 and R07/ R09, were conducted. In the first set, the runs were terminated immediately after pretreatment without introducing vacuum residue, while for the second set, the runs were terminated after vacuum residue was introduced for 6 hours only. The catalysts in runs R06 and R07 were presulfided as described in the Experimental Section, while those in runs R08 and R09 were simply soaked in recycled gas oil for 2 hours, simulating a practice adopted by the industry. A comparison of the carbon percentages of the spent catalysts (Table 4) of test runs ROl and R02 with those of test runs R07 and R09 shows that all four catalyst samples have nearly the same carbon content. This clearly demonstrates that almost all of the coke on the spent catalyst is deposited during the first few hours of the run. Furthermore, the surface area for both presulfided and unsulfided catalysts was significantly reduced during the early hours of the run. 

The data from the simulated cracking process may also be assembled in groups. Statistical evaluation of the groups A vacuum residues and bitumens (samples 1-13), B atmospheric residues (samples 14-17), and C products from conversion processes which can be cracked under the given experimental conditions (samples 19-22) is shown in table 4-34 ... 

Pig- 4-159 Simulated Distillation by Thermogravimetry Curve 1 n-Hexacontane Curve 2 n-Hexylpyrene Cuive 3 Vacuum Residue... 

It may be seen from Fig. 4-163 and 4-164 that the pyrolysis behavior of the vacuum residue is governed fundamentally by its oil component (dispersion medium). The steadiness of the functions E = f(F) and log A = f(P) permits extrapolation towards higher pressures. These plots show that neither n-hexacontane nor n-hexylpyrene are suitable as model substances for simulation of the pressure dependence of the pyrolysis behavior of heavy components of petroleum. 

The behavior of a vacuum residue from a Venezuelan crude was simulated by a distillation bitumen B80 (according to DIN 1995). Further, a vacuum residue of a Middle East crude (VR Kuwait) and its colloid components, i.e. dispersion medium, petroleum resins, and asphaltenes were investigated. Those substances were characterized by element analysis and average relative particle weight (molecular weight) (Table 4-200) and by analysis of their colloid composition according to Neumann [4-10] (Table 4-201). 

In Section 3.4, we investigate the deep-cut operation to produce more VGO from vacuum residue by using VDU simulation. This workshop provides a step-by-step guideline of how to conduct the inveshgahon through Aspen HYSHS/Refining. 

Reza, S., Mohaddecy, S., Sadighi, S. 2011. Simulation and kinetic modeling of vacuum residue soaker-visbreaking. Petrol. Coal 53(l) 26-34. 

Simulation with Different Vacuum Residues as Feedstock... 

The results obtained from the simulated distillation analysis of the products were used to calculate the relative amounts of the fractions of naphtha, middle distillates, vacuum gas oil, and unconverted vacuum residue. The boiling ranges of each of the fractions considered in this study are naphtha IBP— 204°C, middle distillates 204°C-343°C,... 

For each reaction, a kinetic expression (r was formulated as a function of the product composition (y, kinetic constant, and effectiveness factor. Product compositions were determined from bench-scale mass balances and simulated distillation curves. The hydrocracking of vacuum residue was considered to follow second-order reaction, while the remaining reactions were assumed to be first-order as reported in the literature (Sanchez and Ancheyta, 2007). On the basis of these considerations, the reaction rates of the proposed model are as follows ... 

By using an effective, distance-dependent dielectric constant, the ability of bulk water to reduce electrostatic interactions can be mimicked without the presence of explicit solvent molecules. One disadvantage of aU vacuum simulations, corrected for shielding effects or not, is the fact that they cannot account for the ability of water molecules to form hydrogen bonds with charged and polar surface residues of a protein. As a result, adjacent polar side chains interact with each other and not with the solvent, thus introducing additional errors. 

The physical model was proposed to describe the adsorption/desorption processes of the residual gases on the cathode surface. This model takes into account the destruction of the adsorbed layer due to the ion bombardment. The simulation results have a good agreement with the experimental data both on storage and operation stages. Moreover to prove an applicability of proposed model it should be emphasized that a single set of model parameters describe the behavior of the tested cathode under other experimental condition (current density, vacuum level and so on). 

Several of the commercial simulation programs offer preconfigured complex column rigorous models for petroleum fractionation. These models include charge heaters, several side strippers, and one or two pump-around loops. These fractionation column models can be used to model refinery distillation operations such as crude oil distillation, vacuum distillation of atmospheric residue oil, fluidized catalytic cracking (FCC) process main columns, and hydrocracker or coker main columns. Aspen Plus also has a shortcut fractionation model, SCFrac, which can be used to configure fractionation columns in the same way that shortcut distillation models are used to initialize multicomponent rigorous distillation models. 

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