True Boiling Point Curve Research Articles

How Do Methane, Carbon Dioxide or Fatty Acids Affect Waxy Crude Oils?

In the oil and gas industry, wax formation and deposition are common problems, particularly during production and transportation. To better understand the expected behaviour of a given waxy crude oil and consequently select the best solution to prevent wax deposition, it is vital to conduct laboratory tests or numerical simulations to model its performance. For a Brazilian oil field, the phase behaviour of 17 crude oils was modelled using Multiflash software. To tune the model, laboratory tests were used, including true boiling point curves and viscosity tests. This study followed two stages: the first allowed characterization of the wax appearance temperature (WAT) and determination of the expected precipitation curves for these crude samples, and the second stage was evaluation of the impact on wax precipitation after the addition of methane (CH4), carbon dioxide (CO2) or fatty acid (CH3(CH2)nCOOH). Results showed that WAT varied between 47.5 °C and 51.6 °C for these crude oil samples at atmospheric pressure, considering the differential scanning calorimetry (DSC) method. Furthermore, the percentage of wax mass formed varied between 13.3% and 18.3%. By adding the aforementioned chemicals as an inhibitor, it is possible to observe a reduction in the paraffin precipitation tendency. Inhibition was compared in terms of effectiveness between the chemicals studied, and it was concluded that adding myristic acid (C14:0), oleic acid (C18:1), palmitic acid (C16:0), or lauric acid (C12:0) was the most effective in reducing the WAT value. In fact, when adding 25% mole fraction, CH4 and CO2 can reduce the WAT value by up to 4%, but the results are strongly dependent on the fluid pressure. Myristic acid was the most effective in reducing the WAT value by up to 5%, and the results were less pressure dependent.

Evaluation of Micro-Distillation Methodology in Obtaining the Oil Distillation Curve Using Design of Experiments

In the evaluation of petroleum, the true boiling point (TBP) curve stands out among the characterization analyzes, as it is fundamental to assist in decision making such as pricing, royalty payment and petroleum valuation. This is possible by defining the yields of petroleum derivatives obtained as a function of their true boiling points. Its obtainment can partially conducted by applying the ASTM D2892 methodology, for fractions with temperatures up to 673 kelvin. Requiring a minimum volume of 1200 mL of oil and an average time of 48 hours. The present work aims to evaluate the feasibility of applying micro-distillation in the construction of the TBP curve, with volume and time reduction using reference oil. For this, established experiments will conducted according to the application of experiment planning and their results will compared with the curve obtained under standard conditions by ASTM D2892. The variables studied were distillation column size, heating rate control and magnetic bar shape. As a result, two conditions provided adjustment to the validation curve across the entire length of the conventional TBP ASTM curve, with the possibility of using columns of different sizes, minimum sample volume of 700 mL and reduction of total time to 16 hours and 40 minutes.

Dependence of TBP (true boiling point) curve for oil on the method for determining the fractional composition

The subject of this study is the study of methods for determining the fractional composition of oil. 
 The purpose of this work is to assess the influence of the method of determining the fractional composition on the oil TIC on the example of the Salymskoye field. 
 This article describes the comparative results of determining the fractional composition of the oil of the Salym field, obtained by three different methods: atmospheric vacuum distillation, the Engler method, simulated distillation in a gas chromatographic column. 
 The results obtained show which currently depends on the goals and objectives is a more effective method for the study of heavy oils, oil residues and petroleum products.

Prediction of the ASTM and TBP distillation curves and specific gravity distribution curve for fuels and petroleum fluids

AbstractA predictive approach called the six‐point method is developed to construct distillation curves of different petroleum fluids based on the information of six points of the distillation curve at volume percentages (5, 10, 30, 50, 70, and 90). Indeed, six diverse mathematical equations are developed, which establish relationships between the six mentioned distillation temperatures and physical properties ( and ) of petroleum fluids. Having predicted the six points, a third‐order polynomial curve can easily be fitted over these data. Accordingly, the six‐point method is well capable of predicting the distillation curve of both American Society for Testing and Materials (ASTM) D86 and true boiling point (TBP) data for any arbitrary petroleum fluid using only their physical properties. Two auxiliary relations are also presented to estimate the physical properties that may not be available for a petroleum fraction. These relations enable the model to receive pairs of () and () as input parameters, instead of (). A useful transfer function is also developed to convert the TBP curve predicted by the six‐point method to the specific gravity distribution curve. Furthermore, a new set of experimental data obtained from the distillation test is also presented in this work. The experiment has been performed on the petroleum cuts resulting from the crude oil atmospheric distillation unit and Linear Alkyl Benzene (LAB) production unit. The model performance was carefully evaluated against a wide range of literature data as well as new experimental data provided in this study, and the mean of average absolute deviations (AAD%) values was 1.98% for about 233 samples, including 2039 data points.

Online product quality estimator based on true dew point curve for control of crude distillation units

AbstractOperational excellence for Distillation Units and particularly for Crude Distillation Units is achieved by tight control of product quality which is usually estimated by inferential models. This article is focused on a novel approach leading to calculate an appropriate input to the inferential model strictly related to the characteristics of real feed to the column rectifying section where the separation of products occurs. The calculation simplicity based on usually available plant measurements is an additional feature of the proposed approach. This article introduces the definition of a novel curve characterizing hydrocarbon streams: the True Dew Point curve (TDP), whose name recalls the strong relationship with True Boiling Point curve (TBP). Inferential results obtained with the TDP curve have been performed adopting an approximation of the rectifying feed TDP curve with the assumption that any more accurate TDP curve description would give better results. Inferential validation has been carried out comparing the estimations with two different approaches: one based on model input derived from the crude feed TBP curve, assuming that is known and considering these results as benchmark, the other based on a pilot tray temperature (assuming available) as model input for each product. A general database has been built running rigorous simulation models of an atmospheric fractionator, with variations of most operating parameters affecting the distillation ASTM 95% quality chosen as product specification. This article suggests the way to solve problems deriving from high nonlinearity of feed TBP curves, showing the application of TDP methodology to a vacuum fractionator. An application to real laboratory and plant data of atmospheric fractionator is also shown.

Crude-specific Optimal Operation of Hydrodesulfurization

Crude oil has different characteristics according to its origin, and this difference causes suboptimal operation if not considered. Similar to other refinery operations, hydrodesulfurization suffers from lacking this knowledge. Information on the true boiling point curve of the feed, next to its sulfur concentration, can be used to optimize the operating temperature. In this work, an optimization problem is demonstrated for two manipulated temperatures of the system and solved by using a gradient-based and a gradient-free algorithm. While the gradient based solution has a single objective of minimum sulfur content, the gradient-free solution has three objectives: minimum sulfur, inlet temperature, and secondary hydrogen flow rate. A continuous lumping model is used to predict the temperature and sulfur responses of a real hydrodesulfurization plant. An adaptive approach is preferred for the model to cope with the catalyst deactivation interference on the product sulfur content constraint. The effect of changing feed on optimality is demonstrated by using eight types of feeds with varying true boiling point and sulfur content. In addition to that, the impact of catalyst age is shown on similar feed processed on different dates.

Comparison of different distillation columns used to obtain the true boiling point curve

Comparison of different distillation columns used to obtain the true boiling point curve

Surrogate generation and evaluation of gasolines

Fuel surrogates are substitute mixtures that are developed to reproduce real fuels’ physical and chemical properties. These mixtures are created with a small number of components, considering their application in various types of simulations and for bench tests. In the present paper, new gasoline surrogates are proposed by extending and applying an algorithm which was previously developed and successfully used to create diesel surrogates. The five target properties chosen for surrogate optimization include the true boiling point curve (TBP), the research octane number (RON), the liquid density, the carbon-to-hydrogen (C/H) ratio and the oxygenate content. The algorithm is applied to three target fuels, comprising two reference fuels from the FACE working group and one typical oxygenated gasoline that is commercially available in Europe. The proposed surrogates consist of six chemical components which are also represented in reaction kinetics for fuel combustion. An experimental comparison of the boiling point curves, densities and RONs among the surrogates and their respective target fuels provided evidence that the proposed surrogates excellently reproduce the real fuels’ properties.

Learning about distillation curves as a way to define a process stream from crude petroleum

The advanced courses of Separation Processes use to include some reference to the different types of distillation curves, such as the True Boiling Point (TBP) curves, in order to characterize crude petroleum or its derivatives. The concept of pseudocomponents as well as the way to extract them from a TBP curve can be easily understood by reading classical bibliographic references. Chemical process simulation software packages serve as a useful tool that, once the desired number of pseudocomponents to be considered has been specified, automatically generate them. Nevertheless, the lack of correspondence between cuts of a TBP curve and zones with slight temperature changes makes difficult to identify pseudocomponents and to decide on the adequate number of pseudocomponents to be defined. In this work, a very simple exercise is proposed to introduce the idea of TBP distillation curves in the classroom and to explore their characteristics through the analysis of the influence of the number of extracted pseudocomponents.

Determination of flash point and Reid vapor pressure in petroleum from HTGC and DHA associated with chemometrics

Flash point (FP) and Reid vapor pressure (RVP) are physicochemical properties of crude oil that are used as safety and environmental parameters. In this paper, we propose a methodology for estimating the FP and RVP for crude oil by means of detailed hydrocarbon analysis (DHA) and high temperature gas chromatography (HTGC) associated with partial least squares (PLS) regression. These techniques were used due to their direct relationship to FP and RVP. We studied 107 crude oil samples (with an API gravity range of 11.4–54.0) collected from a Brazilian sedimentary basin. The curve data derived from these two techniques were merged to better describe the true boiling point curve. Using fusion information drawn from the two chromatographic techniques (DHA and HTGC), we estimated the flash point with an average error of 5.3 °C and a coefficient of determination of approximately 0.9. While the data fusion represents an information gain in the estimation of the flash point, for to estimate the Reid vapor pressure, the HTGC data are sufficient. The PLS regression generated the best Reid vapor pressure results, with an average error of 0.4 kPa and with a coefficient of determination of above 0.99.

Scheduling Multipipeline Blending Systems Supplying Feedstocks to Crude Oil Distillation Columns

Different types of crude oils, including heavy sour crudes, are usually processed in oil refineries. They are suitably mixed in multipipeline crude oil blending systems (MCOBS) to get qualified feedstocks for the crude distillation units (CDUs) that separate them into various fractions or cuts. Current research on the scheduling of such refinery operations seeks to minimize the total operating cost while limiting the concentration of some impurities in the feedstock. However, an essential property like the feedstock composition usually approximated by the true boiling point (TBP) distribution curve is often ignored. In fact, one of the major goals of the blending process is to supply feedstocks to the CDUs that consistently produce the desired proportions of final cuts to match refined product demands. This work introduces a novel slot-based mixed-integer nonlinear programming (MINLP) formulation for the MCOBS scheduling problem that explicitly accounts for the TBP curves of the crude oils to get a series of suitable and stable feedstocks for the CDUs. An MILP-NLP solution strategy is proposed to find near-optimal schedules in reasonable CPU times.

Extending the true boiling point curve of a heavy crude oil by means of molecular distillation and characterization of the products obtained

ABSTRACTPetroleum is evaluated by means of the true boiling point (TBP) curve, making possible to investigate the yields of the products that will be obtained in refineries, as well as establishing operating strategies and process optimization. Refineries determine TBP curves until 838 K. With molecular distillation the TBP can reach values up to 973 K. Molecular distillation shows potential in the separation, purification, and concentration of products. Eta residue is fractioned and the TBP of the whole crude oil is extended. Products of the distillation were characterized by density, SimDis (simulated distillation), and molar mass. Results showed that density and molar mass of the cuts obtained increase as the process temperature increases. These analyses confirm the efficiency of the separation method by molecular distillation.

Re-express hydrothermal liquefaction bio-crude in petroleum way

Bio-crude obtained from algae by hydrothermal liquefaction (HTL), is considered to be one of the major emerging fuel feedstocks and, as such, has drawn considerable attention from a number of researchers. However, its complex composition has stifled the development of this material in the effort to utilize it as a replacement for conventional petroleum transportation fuels. In addition, the high nitrogen content of the algal-based crude oil presents a high NOx emission risk during its combustion. Characterization of this crude product is important for defining the separation of the material and in defining its reactions in the areas of fuel production and denitrification. This work attempted to define the bio-crude using conventional petroleum industry metrics by replacing pseudo-components with real components. Specifically, the true boiling point (TBP) curve of the bio-crude oil was established using actual GC–MS results and thermogravimetric analyses (TGA). This current combination of analyses represents an inconvenient method for defining the TBP of bio-crude oil. The approach entailed using commercial process simulators to interpret accumulative TGA results as a mass-based TBP curve data input. Then, instead of generating pseudo-components through built-in mathematical methods, typical (or specific) real components of the cascade TBPs were selected from the GC–MS results to form a discrete TBP curve. This new curve provided a component table that included typical, but limited, real components. A simulation of the distillation process was then conducted to characterize the composition of the bio-crude and the distribution of nitrogen in the distillate cuts. The diesel fraction in the simulated distillation of the bio-crude sample accounted for the largest fraction and the nitrogen content was evenly distributed between the fractions which were obtained by separation methods.

Colombian fusel oil

By-products valorization in bio-fuels industry is an important issue for making the global process more efficient, more profitable and closer to the concept of biorefinery. Fusel oil is a by-product of bioethanol production that can be considered as an inexpensive and renewable raw material for manufacturing value-added products. In this work, results in terms of composition and physicochemical properties of six samples of fusel oil from industrial alcohol facilities are presented. Composition of the main components was established by gas chromatography. Complementary techniques, such as headspace solid-phase microextraction and gas chromatography–mass spectrometry (GC-MS), were used for detection of minor components. Fifty-five compounds were identified. Physicochemical properties such as density, acid value, moisture content and true boiling point curves were determined. Results are useful in the conceptual design of separation strategies for recovering higher alcohols, as well as to consider new options of valorization alternatives for fusel oil.

Hybrid model for optimization of crude oil distillation units

Planning, scheduling, and real time optimization are currently implemented using different types of models, which causes discrepancies between their results. This work presents a single model of a crude distillation unit (preflash, atmospheric, and vacuum towers) suitable for all of these applications, thereby eliminating discrepancies between models used in these decision processes. Product true boiling point (TBP) curves are predicted via partial least squares model from the feed TBP curve and operating conditions (flows, pumparound heat duties, furnace coil outlet temperatures). Combined with volumetric and energy balances, this enables prediction of crude distillation on par with a rigorous distillation model, with 0.5% root mean square error (RMSE) over a wide range of conditions. Associated properties (e.g., gravity, sulfur) are computed for each product based on its distillation curve and corresponding property distribution in the feed. Model structure makes it particularly amenable for development from plant data. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1065–1078, 2016

Comparison of Methods for Computing Crude Distillation Product Properties in Production Planning and Scheduling

Production planning and scheduling optimize feedstocks usage in refineries by using crude simplified distillation models which relate feed true boiling point (TBP) curves to product TBP curves and from these calculate product yields and properties. We compare product yield and properties calculated by the swing-cut methods (fixed-cut, weight/volume transfer, and light/heavy) with results from the pseudocuts TBP-based method. The latter uses product yields and TBP curves computed via the hybrid distillation model. Swing-cut methods use assumptions which lead to lower accuracy of predicting yields vs hybrid model yields, resulting in errors in computed bulk product properties. If swing-cut methods yields are replaced by the correct yields from hybrid model, all four methods have approximately the same accuracy. Therefore, for a mixture of crudes, by using accurate yields from the hybrid model, product bulk properties can be computed by blending rules as simple as those used by the fixed-cut swing method.

Optimizing the Polynomial to Represent the Extended True Boiling Point Curve from High Vacuum Distillation Data Using Genetic Algorithms

Optimizing the Polynomial to Represent the Extended True Boiling Point Curve from High Vacuum Distillation Data Using Genetic Algorithms

A simulation of diesel hydrotreating process with real component method

Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estimated by empirical relations and cannot be associated with actual chemical reactions, as no molecular structure is available for pseudo-components. This limitation can be overcome if real components are used. In this paper, a real component based method is proposed for the simulation of a diesel hydrotreating process by using the software of Unisim Design. This process includes reaction units and distillation units. The chemical reaction network is established by analyzing the feedstock. The feedstock is characterized by real components, which are obtained based on true boiling point curve. Simulation results are consistent with actual data.

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.

Fractionation and Characterization of a Petroleum Residue by Molecular Distillation Process

In this work, an atmospheric petroleum residue was fractionated using a falling film molecular distillation pilot plant with molecular distillation temperatures ranging from 190 to 320 °C. The process produced four distillate cuts and four residues that were characterized in order to evaluate the efficiency of the technique. The results showed a gain of 11.7% in distillate yield in the highest molecular distillation temperature studied. Physicochemical characterization of the fractions demonstrated that complex compounds were separated of the distillate cuts and were concentrated in the residues which have compounds with features of resins and asphaltenes. Furthermore, data from molecular distillation experiments were used to extend the true boiling point curve of the crude oil up to 662 °C with continuity and good agreement with the ASTM curves.