Alessandra Winter

Evaluation of Atmospheric and Vacuum Residues Using Molecular Distillation and Optimization

Abstract The term atmospheric residue describes the material at the bottom of the atmospheric distillation tower having a lower boiling point limit of about 340°C; the term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent boiling point (AEBP) above 540°C. In this work, the objective is to evaluate the behavior of different kinds of Brazilian atmospheric and vacuum residues using molecular distillation. The Falling Film Molecular Distillator was used. For the results obtained through this process, a significant range of temperature can be explored avoiding the thermal decomposition of the material. So these results are very important to the refinery decisions and improvements. The Experimental Factorial Design results showed that the temperature has more influence on the process than the feed flow rate, when a higher percentage of distillate is required.

True Boiling Point Extended Curve of Vacuum Residue Through Molecular Distillation

Abstract Molecular distillation is a separation process that explores high vacuum, operation at reduced temperatures, and low exposition of the material at the operating temperature. The term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent temperature (AET) above 540°C. For the assay of the properties of petroleum and petroleum products, the use of the true boiling point (TBP) distillation analysis is accepted as a common practice; however, for heavy petroleum fractions, some difficulties appear for determination of TBP of these petroleum fractions. The objective of this work is to develop a new and a more appropriated method to extend the TBP curve to use it for characterizing vacuum residue of heavy petroleum. The falling film molecular distillator was used. The results showed that it is possible to extend the TBP curve through molecular distillation process with very good precision.

Reliability–Based Optimization using Surface Response Methodology to Split Heavy Petroleum Fractions by Centrifugal Molecular Distillation Process

The present work aimed to develop an experimental and computational study for optimizing the centrifugal molecular distillation process to split heavy petroleum fractions. On the basis of the balance equations and Langmuir–Knudsen equation, a mathematical model was proposed. The influence of the evaporator temperature (EVT), the feed flow rate (Q) and the interactions between them, on the overall distillate mass flow rate (D) and the distillate yield (%D) was analyzed. A full 22 factorial central plus star rotatable (α = ±√2) composite design was performed in the experimental range from 423.15 to 603.15 K for EVT and from 1.473 to 4.418 kg · h−1 for Q. The optimized conditions, using response surface methodology, established that the EVT must range from 540 to 600 K and the Q from 1.5 to 3.5 kg · h−1. The comparison of the experiment results with the predicted model results shows an acceptable qualitative agreement between the experiment and simulated data.

Estudo da influência dos particulados no fenômeno de agregação dos asfaltenos por espectrometria de varredura óptica

The processing of national petroleums causes many operational problems due to the asphaltene aggregation phenomena. To evaluate the behavior of these phenomena, a study based on optical scan technique was carried out to understand the behavior of pure oils and their mixtures. The evaluation according to criteria established by ASTM D7061-061 gives a result of asphaltene flocculation of according to the separability number. In this study, the aspects related to the existence of colloidal forms of peptized asphaltenes in distinct solvents present in petroleums can cause changes in the kinetics of asphaltene flocculation.

High-boiling-point petroleum fractions upgrading using the centrifugal reactive-molecular distillation process over catalyst: Mathematical modeling and simulation including experimental validation

Abstract The modeling of the reactive molecular distillation process (centrifugal type), in which the molecular distillation process and reactive process occur simultaneously to upgrade heavy petroleum crude oil, is presented in this work. The mathematical model involves equations for the evaluation of the physicochemical properties, in – situ cracking reaction, heat, continuity and material balances. A case study is illustrated for an atmospheric petroleum residue (>673.15 K) of “W” crude oil. The influence of adding a catalyst (3 and 5 wt%) was examined under different operating conditions: the process temperature range was from 473.15 K to 523.15 K (considering a pressure between 40 – 50 Pa) and the constant feed flow rate was 1.473 kg h -1 . The results showed that the concentration of the pseudocomponent “a” shrank in both the s – and r – directions reaching an extent conversion of the feedstock about 50% with 3 and 5 wt% of catalyst. Due to the rapid temperature rise in the thin liquid film, the thickness of the film rapidly decreased in this region, whereas the amount of distillate from the split molecules continuously increased throughout the evaporator under the selected conditions. The experimental results agreed well with those obtained from the theoretical simulations, indicating the accuracy and reliability of the mathematical model, since the average percent error was no larger than 6.82%, 9.39% and 14.92% for the distillate flow rate and the extent of conversion in the distillate and in the residue stream, respectively.

Wettability Alteration in Limestone and Dolomite With Brines and CO2

Wettability test is one of the most used tools for evaluating rock/fluid interaction in oils reservoir. In the present paper two carbonate outcrop rocks are evaluated for wettability alterations when subjected to brine injections of varying salinities and content of dissolved CO2. The evaluation included a qualitative appraisal via spontaneous imbibition tests and a quantitative assessment by the Amott-Harvey procedure. Rocks refer to limestone and dolomite samples with petro-physical properties similar to the Brazilian pre-salt reservoirs. Testing fluids are a medium gravity crude oil, seawater concentration brine, formation equivalent brine and the carbonated version of these brines. Results show additional oil recovery directly associated with wettability alteration provoked by brine concentration changes. Increments in recovery were observed independently if the brine concentration decreased or increased in the replacement process. For dolomites and limestone wettability changed in the direction of turning the rock from oil-wet to neutral wet. Tests carried out with equivalent carbonated brines show that similar alteration in the wetting properties also occur. Alterations were as well independent of the increase or decrease of the salt concentration in the brine changed. However, CO2 or its derived ions dissolved in the brines seem to inhibit the mechanism of wettability change when rocks are subject to changes in brine salt concentrations.Copyright