L.C. Medina

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.

An Experimental Study of a Pilot Plant Deasphalting Process in CO2 Supercritical

The authors aimed to study the deasphalting process on laboratory scale through the design and development of a supercritical extraction experimental unit. The experimental unity used in tests is composed by a pump, an extractor with useful volume of 3 L and one separator vessel. Extractions in supercritical conditions were carried out using petroleum residue (vacuum and atmospheric residuum) as feedstock and dioxide carbon (CO2) as solvent. Temperature and pressure were manipulated in order to maintain the solvent in the required conditions, thus facilitating the extraction process and avoiding sharp changes in the system. In supercritical conditions, the products in the deasphalted oil stream present adequate characteristics for the production of lubricant oils and those in the asphalt residue stream present an elevated concentration of asphalt molecules.

An Experimental Study of a Pilot Plant Deasphalting Process in Subcritical and Supercritical Conditions

The authors aimed to study the deasphalting process on laboratory scale through the design and development of a supercritical extraction experimental unit. Extractions in subcritical and supercritical conditions were carried out using petroleum residue as feedstock and propane as solvent. Temperature and pressure were manipulated in order to maintain the solvent in the required conditions, thus facilitating the extraction process and avoiding sharp changes in the system. In supercritical conditions, the products in the deasphalted oil stream present adequate characteristics for the production of lubricant oils and those in the asphalt residue stream present an elevated concentration of asphalt molecules.

Experimental Study of a Pilot Plant Deasphalting Process in Ethanol Sub and Supercritical Phase

The authors aimed to study the deasphalting process on laboratory scale through the design and development of a subcritical and supercritical extraction experimental unit. The experimental unity used in tests is composed by a pump, an extractor with useful volume of 3 L and one separator vessel. Extractions in sub- and supercritical conditions were carried out using petroleum residue (vacuum residuum) as feedstock and ethylic alcohol as solvent. Temperature and pressure were manipulated in order to maintain the solvent in the required conditions, thus facilitating the extraction process and avoiding sharp changes in the system. In both phases, the products in the deasphalted oil stream present adequate characteristics for the production of lubricant oils and those in the asphalt residue stream present an elevated concentration of asphalt molecules.

Recovery and Characterization of Petroleum Residues Through the Molecular Distillation Process

Molecular distillation process is an efficient way to separate complex residues to obtain improvement and a more complete characterization of crude oils. It presents advantages such as to generate distillation products that can be experimentally characterized, and the operation conditions of this process generate distillate cuts with an atmospheric equivalent boiling point (AEBP) above 650°C without risks of thermal degradation. The aim of this work is to carry out the separation of two vacuum residues (VR) within the process temperature range from 550 to 670°C, using the Brazilian Molecular Distillation equipment. As a result, five distillate cuts and five residues from molecular distillation processing were generated. The molecular distillation (MD) technique provided a gain in distillate yield of about 10% over the conventional methods. The efficiency of the technique was verified through the vapor pressure osmometry experiments and the extension of true boiling point (TBP) curves of petroleum. The extended TBP curves by the molecular distillation process demonstrated that this alternative method is appropriate to extend the TBP curves to temperatures above those of the conventional methods.

Separating Asphaltenes from Lube Oil Through Supercritical Deasphalting Considering Experimental and Virtual Plants and Thermodynamic Analysis

Abstract Studies of petroleum asphaltenes have gained considerable attention in the past decades due to the increasing production of heavy crude oils. The reduction of light crude oil reservoirs and the increasing of light oil demand, forced the petroleum industry to develop upgrading processes for raw materials and residues. Due to the limited global oil reserves, more and more heavy crudes are being processed. These crudes contain large amounts of asphaltenes and resins. Petroleum must be processed in order to have the major quantity of higher aggregated compounds. All types of petroleum are colloidal systems. In a dispersion medium consisting mainly of hydrocarbons, which can be classified into alkanes, naphthenes and aromatics, there are two groups of dispersed colloidal particles in solution: asphaltenes and petroleum resins. Reduction of asphaltenes and metal content can be achieved by disturbing the solvatation equilibrium via addition of suitable solvents, e.g., propane. The Residuum Oil Supercritical Extraction (ROSE™) process is the premier deasphalting technology available in industry today. This state-of-the-art process extracts high-quality deasphalted oil (DAO) and asphaltenes from atmospheric or vacuum residues and other heavier feedstocks. The ROSE process operates near to the critical point of the solvent and applies thermodynamic fundamentals and high-pressure phase equilibrium principles in order to provide an energy-efficient process. Depending on the solvent selection, the DAO can be an excellent feedstock for catalytic cracking, hydrocracking, or lube oil blending. The energy consumption in supercritical extraction is considerably lower than in conventional extraction, which requires a higher ratio of solvent to crude. The use of supercritical fluid has some advantages such as higher yield and improved quality of the valuable DAO and asphaltenes product, and recovery of the supercritical solvent, reducing significantly operating costs compared to other solvent deasphalting processes. This work presents a new method for petroleum deasphalting. The proposal involves the extraction of the residue fractions from molecular distillations using supercritical propane or pentane as solvent. The thermodynamic calculation and representation of the ternary system is shown. The calculation is very complex since the asphaltenes have to be represented as a set of molecules whose properties have to be predicted using special methodology and the UNIFAC method. Our research group at State University of Campinas (UNICAMP) has developed a real supercritical extraction pilot plant and a virtual one which are optimized and validated. This work is carried out in association with Petrobras (Brazilian Oil Company).

Development of correlation for extension of the true boiling point (TBP) and molar mass

ABSTRACT The true boiling point curve (TBP) is an important tool for the petroleum industry; it is used to obtain the behavior of petroleum during distillation. This work developed a correlation for the extension of the TBP curve by means of molecular distillation. TBP curve is well established for a temperature of 565°C in a conventional distillation. With the correlation developed, it is possible to reach values near 1,000°C. A second correlation was also developed for predicting the values of molar mass of waste petroleum. Both correlations demonstrated to be valid and represent a great advancement for the petroleum industry.

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.