US20200140764A1

US20200140764A1 - System and method for solvent de-asphalting

Info

Publication number: US20200140764A1
Application number: US16/336,206
Authority: US
Inventors: Nestor Gregorio ZERPA; Yuhan Xia; Milan TODOROVIC
Original assignee: CNOOC Petroleum North America ULC
Current assignee: CNOOC Petroleum North America ULC
Priority date: 2016-09-26
Filing date: 2017-09-21
Publication date: 2020-05-07
Also published as: CN109790471A; WO2018053619A1; CA3038209A1

Abstract

A de-asphalting system for solvent de-asphalting including a desasphalter and a controller. The deasphalter defines a contacting zone and a separation zone. The contact zone contacts a feed, including asphaltenes, and a solvent to form a mixture, where the contacting of the feed and the solvent causes at least a portion of the asphaltenes to precipitate out of the mixture. The contacting is disposed at an operating temperature. The separation zone separates the mixture into a de-asphalted oil-comprising material fraction (“S+PDAO”) and a asphaltene-rich material fraction. The asphaltene-rich material fraction includes the precipitated asphaltenes. The controller controls at least one operating parameter of the deasphalter based on at least on a refractive index of the S+PDAO phase. The operating parameter is selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the mass of precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the mass of the solvent to the mass of the feed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase of International Application No. PCT/CA2017/000208, filed on Sep. 21, 2017, and claiming priority from U.S. Provisional Application No. 62/399,809 filed Sep. 26, 2016, the content of which is hereby incorporated by reference in its entirety.

FIELD

The invention relates to a process for upgrading heavy oil and/or bitumen. Specifically, the process relates to a process for de-asphalting heavy oil and/or bitumen.

BACKGROUND

Heavy oil and/or bitumen are often difficult to transport from production sites due to high viscosities at typical handling temperatures. They generally need to be diluted by the addition of at least one low density and low viscosity diluent to make the heavy oil and/or bitumen transportable, particularly when transporting over long distances.
There are several disadvantages of adding diluent to heavy oil and/or bitumen to produce transportable oil including: availability of diluents, typically light hydrocarbons, such as gas condensates, is steadily decreasing worldwide, making them more expensive to procure; and the diluent takes up pipeline space without adding value
For example, in Canada, when making transportable oil and using gas condensate as a diluent, the volume of gas condensate added to the bitumen is typically 30 to 35% of the total product.
One method for addressing the difficulties for handling heavy oil and/or bitumen is solvent de-asphalting. Solvent de-asphalting is a process that removes the asphaltenes fraction from a hydrocarbon feed using a solvent. Solvent de-asphalting is described in, and amongst other sources, the article by Billon and others published in 1994 in Volume 49, No. 5 of the journal of the French Petroleum Institute, pages 495 to 507, in the book “Raffinage et conversion des produits lourds du petrole [Refining and Conversion of Heavy Petroleum Products]” by J. F. Le Page, S. G. Chatila, and M. Davidson, Edition Technip, pages 17-32. Exemplary solvent extraction processes, for effecting the de-asphalting, are described in U.S. Pat. No. 7,597,794.
When the solvent is mixed with the hydrocarbon feed in an extractor, asphaltenes (which are insoluble in certain solvents) precipitate from the mixture. These precipitated asphaltenes are recovered from the bottom of the extractor, while the remaining hydrocarbons are recovered along with the solvent from the top of the extractor. The solvent is then separated from the remaining hydrocarbons. This asphaltene-lean hydrocarbon stream has improved properties compared to the original hydrocarbon feed due to the reduction or elimination of undesirable asphaltenes.
J S Buckley et al, “Asphaltene Precipitation and Solvent Properties of Crude Oils”, (1998) 16:3-4 Petrol Sci and Tech 251 show that the prediction of the onset of asphaltene precipitation at ambient conditions may be improved using refractive index (RI) to characterize crude oils and their mixtures with precipitants and solvents. However, Buckley does not teach the significance of RI at solvent de-asphalting process conditions, which occur after the onset of precipitation and at higher temperatures and pressures.
K Akbarzadeh et al, “A generalized regular solution model for asphaltene precipitation from n-alkane diluted heavy oils and bitumens”, (2005) 232 Fluid Phase Equilibria 159 discloses a solvent de-asphalting model. However, these models are not very robust, rely on parameters that cannot be easily measured or estimated, and have low accuracy.
There exists a need for improved solvent de-asphalting systems and methods.

SUMMARY

In one aspect, there is provided a method for solvent de-asphalting including selecting a solvent based on RI and contacting the selected solvent with a feed including asphaltenes to effect de-asphalting.
In another aspect, there is provided a de-asphalting system for solvent de-asphalting including a deasphalter and a controller. The deasphalter defines a contacting zone for contacting a feed, including asphaltenes, and a solvent to form a mixture, where the contacting of the feed and the solvent causes at least a portion of the asphaltenes to precipitate out of the mixture, the contacting disposed at an operating temperature; and a separation zone to separate the mixture into a de-asphalted oil-comprising material fraction (“S+PDAO”) and a asphaltene-rich material fraction, the asphaltene-rich material fraction including the precipitated asphaltenes. The controller controls at least one operating parameter of the deasphalter based on at least on a refractive index of the S+PDAO phase. The operating parameter is selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the mass of precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the mass of the solvent to the mass of the feed.
In some embodiments, the de-asphalting system further includes at least one flow regulator operatively connected to the controller for controlling a feed flow rate of the feed, a solvent flow rate of the solvent or both.
In some embodiments, the de-asphalting system further includes a temperature regulator operatively connected to the controller for controlling the operating temperature of the contacting zone.
In some embodiments, the de-asphalting system further includes a refractive index determining device operatively connected to the controller for determining the refractive index of the S+PDAO.
In some embodiments, the refractive index determining device is a refractometer. In some embodiments, the refractive index determining device is a densitometer.
In some embodiments, the refractive index of the S+PDAO is calculated as a function of the portion of the precipitated asphaltenes, the refractive index of the feed composition, the refractive index of the solvent, the UOP-K characterization factor of the solvent, and the operating temperature according to the following formulas:
${RI}_{S + PDAO @ T ° C .} = {RI}_{S + {PDAO}_{0} @ T ° C .} + slope \times \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}};$ ${RI}_{S + {PDAO}_{0} @ T ° C .} = A_{0} + (A_{1} \times {RI}_{Feed @ T ° C .} + A_{2} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{3}}; and$ $slope = A_{4} + (A_{5} \times {RI}_{Feed @ T ° C .} + A_{6} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{7}} .$
In another aspect, there is provided a method for solvent de-asphalting including providing a feed, including asphaltenes, at a feed flow rate; providing a solvent at a solvent flow rate; contacting the solvent and the feed at an operating temperature to effect precipitation of at least a portion of the asphaltenes to obtain a S+PDAO and an asphaltene-rich material fraction, where the asphaltene-rich material fraction, includes the precipitated asphaltenes; and controlling one operating parameter based on at least a refractive index of the S+PDAO, the operating parameter selected from: the operating temperature, the composition of the feed, the composition of the solvent, a ratio of the precipitated asphaltenes to the mass of asphaltenes within the feed, and a ratio of the feed flow rate to the solvent flow rate.
In another aspect, there is provided a deasphalted oil obtained by a method including the steps of: providing a feed, including asphaltenes, at a feed flow rate; providing a solvent at a solvent flow rate; contacting the solvent and the feed at an operating temperature to effect precipitation of at least a portion of the asphaltenes to obtain a S+PDAO and an asphaltene-rich material fraction, wherein the asphaltene-rich material fraction includes the precipitated asphaltenes; and controlling one operating parameter based on at least a refractive index of the S+PDAO, the operating parameter selected from: the operating temperature, the composition of the feed, the composition of the solvent, a ratio of the precipitated asphaltenes to the mass of asphaltenes within the feed, and a ratio of the feed flow rate to the solvent flow rate.
In another aspect, there is provided a method for solvent de-asphalting including: defining at least the following operating parameters: a composition of a feed including asphaltenes, a target ratio of a mass of removed asphaltenes to the mass of asphaltenes within the feed, an operating temperature for contacting the feed and a solvent, and a ratio of a feed flow rate of the feed to a solvent flow rate of the solvent; determining an RI of the solvent based at least on calculating the RI of a S+PDAO formed by contacting the feed with the solvent; selecting a solvent based at least on the determined solvent RI; and contacting the selected solvent with the feed at the operating parameters to effect de-asphalting.
In another aspect, there is provided a method for starting up a solvent deasphalting process including: pre-determining four operating parameters, the operating parameters are selected from: an operating temperature, a composition of a feed, a composition of a solvent, a target ratio of a mass of precipitated asphaltenes to a mass of asphaltenes initially within the feed, and a ratio of a feed flow rate to a solvent flow rate; determining the non-predetermined operating parameter based on at least an expected RI of an S+PDAO stream generated by the process; and starting up the process using the pre-determined operating parameters and the determined operating parameter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a system for de-asphalting according to an embodiment.

FIG. 2 shows a method for de-asphalting according to an embodiment.

FIG. 3 shows a product obtained by a method for de-asphalting according to an embodiment.

FIG. 4 shows a method for de-asphalting according to an embodiment.

DETAILED DESCRIPTION

This disclosure is based in part on the surprising discovery that a solvent de-asphalting process can be characterized and/or controlled based at least on refractive index (“RI”) of a product stream.
In one aspect, there is provided a system for de-asphalting 100 (FIG. 1). The de-asphalting system 100 includes a deasphalter 101. A feed 104, including asphaltenes 104 a, and a solvent 106 are contacted within a contacting zone 103 of the deasphalter 101 to form an intermediate mixture 107. The contacting zone 103 is disposed at an operating temperature. The asphaltenes 104 a are insoluble in the solvent 106, and at least a portion of the asphaltenes 110 a will precipitate out of the mixture 107. The mixture 107, resulting from the contacting, is separated in a separation zone 109 of the deasphalter 101, into at least a deasphalted oil-comprising material fraction (“S+PDAO”) 108 and an asphaltene-rich material fraction 110. In this context, the use “at least” suggests that there may be other fractions that are also separated. The asphaltene content of the deasphalted oil-comprising material fraction 108 is less than the asphaltene content of the feed 104. The asphaltene-rich material fraction 110 includes the precipitated asphaltenes 110 a.
The de-asphalting system 100 includes a controller 112 for controlling at least one operating parameter of the de-asphalting system 100 based on at least a RI of the S+PDAO 108. The operating parameter is selected from: the operating temperature; the composition of the feed 104; the composition of the solvent 106; a ratio of the mass of the precipitated asphaltenes 110 a to the mass of the asphaltenes 104 a within the feed; and a ratio of the mass of the solvent 106 to the mass of the feed 104.
In some embodiments, the feed 104 is a heavy hydrocarbon-comprising material. The heavy-hydrocarbon-comprising material may be liquid, semi-solid, or solid, or any combination thereof.
In some embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 10 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 20 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 30 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 40 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 50 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 60 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 70 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 80 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that includes at least 90 weight percent of hydrocarbon-comprising material that boils above 500° C. In some of these embodiments, for example, the heavy hydrocarbon-comprising material is a material that boils above 500° C.
In some embodiments, for example, the heavy hydrocarbon-comprising material includes a Conradson carbon residue content of at least 12 weight percent, based on the total weight of the heavy hydrocarbon-comprising material. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes a Conradson carbon residue content of at least 13 weight percent, based on the total weight of the heavy hydrocarbon-comprising material. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes a Conradson carbon residue content of at least 14 weight percent, based on the total weight of the heavy hydrocarbon-comprising material. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes a Conradson carbon residue content of less than 30 weight percent, based on the total weight of the heavy hydrocarbon-comprising material.
In some embodiments, for example, the heavy hydrocarbon-comprising material includes an asphaltene content of less than 40 weight %, based on the total weight of the heavy hydrocarbon-comprising mixture. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes an asphaltene content of less than 20 weight %, based on the total weight of the heavy hydrocarbon-comprising mixture. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes an asphaltene content of less than 15 weight %, based on the total weight of the heavy hydrocarbon-comprising mixture.
In some embodiments, for example, the asphaltenes are C5-asphaltenes. C5-asphaltenes are material precipitating from a hydrocarbon composition after being mixed with 40 volumes of an n-pentane (n-C5) solvent at room temperature. The C5-asphaltene content of the heavy hydrocarbon-comprising material composition can be determined using ASTM D6560, modified to use pentane as the solvent.
In some embodiments, for example, the heavy hydrocarbon-comprising material includes an inorganic solids content of less than 1 weight %, based on the total weight of the heavy hydrocarbon-comprising mixture. In some of these embodiments, for example, the heavy hydrocarbon-comprising material includes an inorganic solids content of less than 0.5 weight %, based on the total weight of the heavy hydrocarbon-comprising mixture.
In some embodiments, for example, the inorganic solids of the heavy hydrocarbon-comprising material were micrometer (10⁻⁶m) size particles. In some embodiments, for example, the inorganic solids in the heavy hydrocarbon-comprising material were nanometer (10⁻⁹m) size particles.
In some embodiments, for example, the heavy hydrocarbon-comprising material has an API (American Petroleum Institute) gravity of less than 20°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than 15°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than 12°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than 10°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than 5°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than 0°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than −2°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than −4°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than −8°. In some embodiments, for example, the heavy hydrocarbon-comprising material has an API gravity of less than −10°.
In some embodiments, for example, the heavy hydrocarbon-comprising material includes, or in some embodiments, consists of, residuum or resid. Exemplary residuum includes various heavy crude and refinery fractions. In this respect, in some embodiments, for example, the heavy hydrocarbon-comprising material includes, or in some embodiments, consists of, fresh resid hydrocarbon feeds, a bottoms stream from any refinery process, such as petroleum atmospheric tower bottoms, vacuum tower bottoms, or a bottoms stream from a coker or a visbreaker or a thermal cracking unit, or a bottoms stream from a FCC or a RFCC unit, hydrocracked atmospheric tower, vacuum tower, FCC, or RFCC bottoms, straight run vacuum gas oil, hydrocracked vacuum gas oil, fluid catalytically cracked (FCC) slurry oils or cycle oils, as well as other similar hydrocarbon-comprising materials, or any combination thereof, each of which may be straight run, process derived, hydrocracked, or otherwise partially treated (for example, desulfurized). The above-described heavy hydrocarbon-comprising material may also include various impurities, such as sulphur, nitrogen, oxygen, halides, and metals.
In some embodiments, for example, the heavy hydrocarbon-comprising material includes, or in some embodiments, consists of, a crude, such as an heavy and/or an ultra-heavy crude. Crude refers to hydrocarbon material which have been produced and/or retorted from hydrocarbon-containing formations and which has not yet been distilled and/or fractionally distilled in a treatment facility to produce multiple components with specific boiling range distributions, such as atmospheric distillation methods and/or vacuum distillation methods. Exemplary crudes include coals, bitumen, tar sands, or crude oil. In such embodiments, the crude can be characterized as having a number of separable fractions (or “cuts”) that could be separable by distillation, each cut having characterizable properties. In some embodiments, the crude has five cuts: a kerosene fraction, a diesel fraction, a light vacuum gas oil fraction, a heavy vacuum gas oil fraction, and a vacuum residue fraction. In some embodiments, the vacuum residue fraction comprises the asphaltenes.
In some embodiments, the solvent 106 is a suitable hydrocarbon material which is a liquid at the operating conditions of the solvent material contacting zone. In some embodiments, for example, the solvent is a relatively light hydrocarbon or a mixture including two or more light hydrocarbons. Exemplary light hydrocarbons include propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, nonane, and corresponding mono-olefinic hydrocarbons, and corresponding cyclic hydrocarbons. In some embodiments, for example, the solvent includes one or more paraffinic hydrocarbons having from 3 to 10 carbon atoms in total per molecule. In some embodiments, for example, the solvent is pentane. In some embodiments, the light hydrocarbons include light aromatic hydrocarbons. Exemplary light aromatic hydrocarbons include benzene, and toluene.
In some embodiments, for example, the solvent 106 is a supercritical fluid at the operating conditions of the contacting zone 103.
In some embodiments, the operating temperature in the solvent contacting zone is from between about the ambient temperature to about the critical condition of the solvent. In some embodiments, economics will determine the temperature range, even if, theoretically, it may be possible to operate in a significantly wider range. In some embodiments, the upper and lower ends of the operating temperature range is calculated as follows:
T _max =T _c−0.05(T _c −T _o); and
T _low =T _c−0.80(T _c −T _o).
In some embodiments, the operating temperature is between about 80° C. and about 200° C., such as between about 100° C. and about 160° C.
In some embodiments, the asphaltenes 104 a found in the feed 104 are insoluble in the solvent 106. The contacting of the solvent 106 and the feed 104 causes the asphaltenes 104 a found in the feed 104 to precipitate into the asphaltene-rich material fraction 110 while the remainder of the feed 104 is solvated by the solvent 106 to form the deasphalted oil-comprising material fraction 108.
In some embodiments, for example, the separation in separation zone 109 is effected by gravity separation. In some embodiments, for example, the separation is effected by phase separation. In some embodiments, for example, the separation is effected by extraction.
In some embodiments, the asphaltene-rich material fraction 110, being denser than the deasphalted oil material fraction 108, is recovered as a bottoms product, and the deasphalted oil material fraction is recovered as an overhead product.
In some of embodiments, for example, both of the contacting zone 103 and the separation zone 109 is effected within a combined contactor/separator, such as a mixer-decanter or in an extraction column. In this respect, the contacting zone 103 and the separation zone 109 are at least partially co-located. Examples of suitable mixers include rotary stirring blades, paddles, or baffles.
In other embodiments, for example, the deasphalter 101 includes a mixer 103 a, the contacting zone 103 defined by the mixer, and the resulting mixture 107 is then supplied to a separator, the separation zone 109 defined by the separator, to effect the gravity separation. In this respect, the contacting zone 103 and the separation zone 109 are separate.
In some embodiments, the deasphalted oil-comprising material fraction 108 includes substantially all of the solvent 106 and a partially de-asphalted oil, and the asphaltene-rich material fraction 110 includes a pitch and residual solvent.
In some embodiments, the de-asphalting process is characterized by the following operating parameters:

- 1. an operating temperature of the contacting;
- 2. the composition of the feed;
- 3. the composition of the solvent;
- 4. a ratio of the mass of the solvent to the mass of the feed (“S/F ratio”); and
- 5. a ratio of the mass of the precipitated asphaltenes to the mass of the asphaltenes in the feed (“degree of asphaltene separation”).

For example, the operating parameters will affect the properties of the S+PDAO phase at operating conditions. The RI of the S+PDAO phase can be measured, calculated, or both. In some embodiments, four operating parameters are specified, and a selected operating parameter is controlled based on the RI of the S+PDAO phase.
In some embodiments, using the specified operating parameters, the RI of the S+PDAO phase is calculated by two methods. In such embodiments, the selected operating parameter is controlled where the RI values of the S+PDAO phase calculated using the two methods converge. In some embodiments, the selected operating parameter is controlled by obtaining a measured RI of the S+PDAO phase and using at least one of the two calculation methods.
A first method (“Method 1”) for calculating the RI of the S+PDAO uses the following equations:
$\begin{matrix} {RI}_{S + PDAO @ T ° C .} = {RI}_{S + {PDAO}_{0} @ T ° C .} + slope \times \frac{M_{Pitch}}{M_{Feed}^{asphaltenes}} where : & (1) \\ {RI}_{S + {PDAO}_{0} @ T ° C .} = A_{0} + (A_{1} \times {RI}_{Feed @ T ° C .} + A_{2} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{3}} & (2) \\ slope = A_{4} + (A_{5} \times {RI}_{Feed @ T ° C .} + A_{6} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{7}} & (3) \end{matrix}$
In these equations:

- RI_{S+PDAO @T° C.}: RI of the S+PDAO at an operating temperature;
- RI_S+PDAO ₀ _{@T° C.}: RI of the S+PDAO at the onset of precipitation at the operating temperature;
- M_Pitch: mass of the pitch;
- M_Feed ^asphaltenes: mass of the asphaltenes in the feed composition;
- RI_{Feed @T° C.}: RI of the feed at the operating temperature;
- RI_{Solvent @T° C.}: RI of the solvent at the operating temperature;
- UOP-K_SolventUOP-K characterization factor of the solvent; and
- A₀-A₇coefficients determined experimentally through data analysis.

The values of A₀-A₇can be determined by fitting data obtained from experimental results. Alternatively or additionally, the values of A₀-A₇can be determined by calculating RI's of various feeds, solvents and S+PDAOs, and also the UOP-K factors of various solvents.
A hydrocarbon, such as a cut the feed 104 or a component of the solvent 106, can be characterized by its RI. Buckingham, “The Molecular Refraction of an Imperfect Gas” (1956) 52 Transactions of the Faraday Society 747, showed that there is a correlation between RI and density:
$\begin{matrix} \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} \times ρ_{@ T ° C .}^{- 1} = A + B \times ρ_{@ T ° C .} + C \times ρ_{@ T ° C .}^{2} & (4) \end{matrix}$
where:

- RI_{@T° C.}: RI of a compound at temperature T (° C.);
- ρ_{@T° C.}: density of the compound at temperature T (° C.); and
- A, B, C: virial coefficients. Using data for a variety of hydrocompounds, the coefficients can be determined using curve fitting and data analysis.

The hydrocarbon can be further characterized by F_RI, a function of its RI:
$\begin{matrix} F_{RI} = \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} = ρ_{@ T ° C .} (A + B \times ρ_{@ T ° C .} + C \times ρ_{@ T ° C .}^{2}) & (5) \end{matrix}$
J S Buckley et al, “Asphaltene Precipitation and Solvent Properties of Crude Oils”, (1998) 16:3-4 Petrol Sci and Tech 251 showed that at ambient conditions and ideal volume of mixing, the F_RIof a mixture can be calculated based on its components as follows:
$\begin{matrix} F_{RI @ 25 ° C .} = \frac{Σ_{i} (v_{i @ 25 ° C .} \times F_{RI, i @ 25 ° C .})}{Σ_{i} v_{i @ 25 ° C .}} & (6) \end{matrix}$
where:
v_{i @25° C.}: volume fraction of component i in the mixture at 25° C.; and
F_{RI,i @25° C.}: F_RIof component i in the mixture at 25° C.
F M Vargas and WG Chapman, “Application of the One-Third Rules in Hydrocarbon and Crude Oil Systems”, (2010) 290:1 Fluid Phase Equilibria 103 showed a formula for extrapolating the RI of a hydrocarbon at a temperature T, based on the RI and density of the hydrocarbon at a reference temperature and the density of the hydrocarbon at the temperature T:
$\begin{matrix} \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} = \frac{{RI}_{@ T_{0} ° C .}^{2} - 1}{{RI}_{@ T_{0} ° C .}^{2} + 2} \times \frac{ρ_{@ T ° C .}}{ρ_{@ T_{0} ° C .}} & (7) \end{matrix}$
A hydrocarbon, such as a light hydrocarbon, can be characterized by a UOP-K characterization factor. The UOP-K characterization factor can be calculated using the method set out in K M Watson and E F Nelson, “Improved Methods for Approximating Critical and Thermal Properties of Petroleum Fractions”, 1933 85^thMeeting of the American Chemical Society: Symposium on Physical Properties of Hydrocarbon Mixtures:
$\begin{matrix} UOP - K = \frac{\sqrt[3]{BP \times 1.8 + 492}}{\frac{ρ_{@ 15.6 ° C .}}{1000}} & (8) \end{matrix}$
where:
UOP-K: UOP-K characterization factor of the hydrocarbon compound;
BP: boiling point of the hydrocarbon compound; and
ρ_{@15.6° C.}: density of the hydrocarbon compound at 15.6° C.
In embodiments where the solvent 106 includes more than one hydrocarbon, the UOP-K characterization of the solvent can be calculated as a weighted aggregate of the UOP-K characterization factor of each hydrocarbon according to:
UOP-K=Σ_i(w _i×UOP-K_i) (9)
where:
w_i: mass fraction of hydrocarbon, i, in the solvent; and
UOP-K_i: UOP-K characterization factor of the hydrocarbon.
A second method for calculating the RI of the S+PDAO at the operating temperature uses mass balances and the correlations described in equations (4)-(7) (“Method 2”).
In embodiments where RI is calculated using Method 1 and Method 2, an initial value is specified for the selected operating parameter. The initial value is used to calculate the RI of the S+PDAO at the operating temperature using Method 2. The convergence of the RI of the S+PDAO at the operating temperature calculated using Method 1 and Method 2 indicates that the value of the selected operating parameter used in the calculation of Method 2 is the value that should be used in the solvent de-asphalting process. If the values of the RI of the S+PDAO at the operating temperature calculated using Method 1 and Method 2 do not converge, a new value of the selected operating parameter is specified and the RI of the S+PDAO at the operating temperature is re-calculated using Method 2. This calculation can be iterated with new values of the selected operating parameter until the values RI of the S+PDAO at the operating temperature calculated using Method 1 and Method 2 converge.
In some embodiments, the de-asphalting system 100 includes a flow regulator 114 operatively connected to the controller 112 for controlling a flow feed rate of the feed 104, a solvent feed rate of the solvent 106, or both.
In some embodiments, the de-asphalting system 100 includes a temperature regulator 116 operatively connected to the controller 112 for controlling the operating temperature. In some embodiments, the temperature regulator is a heater 111. Examples of suitable heaters include heat exchangers, furnaces, or boilers.
In some embodiments, the de-asphalting system 100 includes a pre-heater (not shown) upstream of the deasphalter 101 for pre-heating the feed 104, the solvent 106 or both.
In some embodiments, the de-asphalting system 100 includes an RI determining device 117 operatively connected to the controller 112 for determining the RI of the S+PDAO 108. In some embodiments, the RI determining device is a refractometer for measuring the RI of the S+PDAO 108. In some embodiments, the RI determining device is a densitometer for measuring the density of the S+PDAO to determine the RI of the S+PDAO, for example, by using the correlation set out in equation (4).
In some embodiments, the de-asphalting system 100 includes a secondary deasphalter (not shown) for removing at least a portion of the asphaltenes present in the S+PDAO phase 108.
In some embodiments, the de-asphalting system 100 includes a S+PDAO separator (not shown) for separating the S+PDAO 108 to obtain a S+PDAO-derived solvent. In such embodiments, the solvent 106 includes at least a portion of the S+PDAO-derived solvent.
In some embodiments, the de-asphalting system 100 includes a pitch stripper (not shown) for separating the asphaltene-rich material fraction 110 to obtain a pitch-derived solvent. In such embodiments, the solvent 106 comprises at least a portion of the pitch-derived solvent.
In another aspect, there is provided a method for solvent deaspalting 200 (FIG. 2). At block 202, a feed, including asphaltenes, at a feed flow rate is provided. At block 204, a solvent at a solvent flow rate is provided. At block 206, the feed and the solvent are contacted to effect precipitation of at least a portion of the asphaltenes to obtain a S+PDAO and an asphaltene-rich material fraction. The asphaltene-rich material fraction, includes the precipitated asphaltenes. The contacting is disposed of at an operating temperature. At block 208, at least one operating parameter is controlled based on at least a refractive index of the S+PDAO, the operating parameter is selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the feed flow rate to the solvent flow rate.
In another aspect, there is provided a deasphalted oil obtained by a method 300 (FIG. 3). At block 302, a feed, including asphaltenes, at a feed flow rate is provided. At block 304, a solvent at a solvent flow rate is provided. At block 306, the feed and the solvent are contacted to effect precipitation of at least a portion of the asphaltenes to obtain a S+PDAO and an asphaltene-rich material fraction. The asphaltene-rich material fraction, includes the precipitated asphaltenes. The contacting is disposed of at an operating temperature. At block 308, at least one operating parameter is controlled based on at least a refractive index of the S+PDAO, the operating parameter is selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the feed flow rate to the solvent flow rate.
In another aspect, there is provided a method for solvent de-asphalting 400 (FIG. 4). At block 402, operating parameters of the de-asphalting are defined, the operating parameters including: a composition of a feed, including asphaltenes; a target ratio of a mass of removed asphaltenes to the mass of asphaltenes within the feed; an operating temperature for contacting the feed and a solvent; and a ratio of a feed flow rate of the feed to a solvent flow rate of the solvent. At block 404, an RI of the solvent is determined based at least on calculating the RI of an S+PDAO formed by contacting the feed with the solvent. At block 406, a solvent is selected based at least on the solvent RI determined at block 404. At block 408, the solvent selected in block 406 is contacted with the feed at the operating parameters defined at block 402 to effect de-asphalting.
In another aspect, there is provided a method for solvent de-asphalting 500 (FIG. 5). At block 502, a solvent is selected based on RI. At block 504, the selected solvent is contacted with a feed including asphaltenes to effect de-asphalting.
In another aspect, there is provided a method for starting up a solvent deasphalting process 600 (FIG. 6). At block 602, four operating parameters are set at pre-determined values, the operating parameters are selected from: an operating temperature; a composition of a feed; a composition of a solvent; a target ratio of a mass of precipitated asphaltenes to a mass of asphaltenes initially within the feed; and a ratio of a feed flow rate to a solvent flow rate. At block 604, the non-predetermined operating parameter is determined based on an expected RI of an S+PDAO stream generated by the process. At block 606, the process is started up using the pre-determined operating parameters and the determined operating parameter.
Other features and embodiments of the invention will become apparent from the following examples which are given for illustration of the invention rather than for limiting its intended scope.

EXAMPLES

In the following illustrative examples, a S/F ratio for a solvent de-asphalting process is controlled.

Example 1: Defining Process Variables

In this example, the S/F ratio is controlled at a first stage de-asphalting operation.
The following four operating parameters are selected:
1. the operating temperature;
2. the feed composition;
3. the solvent composition; and
4. the degree of asphaltene separation.
1) Temperature: In this example, the operating temperature is 165° C.
2) Feed composition:
In this example, the feed composition is bitumen. Bitumen is a mixture of components and can be characterized as having five fractions (or “cuts”): a kerosene fraction, a diesel fraction, a light vacuum gas oil fraction, a heavy vacuum gas oil fraction, and a vacuum residue fraction.
In this example, the bitumen has the following composition:

TABLE 1

Feed composition

	Initial	Final
	Boiling	Boiling		Volume	Density	Density	Density
	Point	Point	Weight	fraction	@ 15.6° C.	@ 25° C.	@ 165° C.
Cut	(° C.)	(° C.)	fraction	@ 25° C.	(kg/m³)	(kg/m³)	(kg/m³)

Kerosene	190	260	0.0215	0.0252		869.88
Diesel	260	343	0.0589	0.0669		899.99
Light Vacuum	343	454	0.1693	0.1844		937.64
Gas Oil
Heavy Vacuum	454	560	0.1776	0.1851		979.38
Gas Oil
Vacuum Residue	560	820	0.5727	0.5384		1,086.01
Total (Bitumen)	190	820	1.0000	1.0000	1,027.60	1,021.03	932.45

The bitumen of this example includes asphaltene having the following properties:

TABLE 2

	Initial	Final
	Boiling	Boiling		Volume	Density	Density	Density
	Point	Point	Weight	fraction	@ 15.6° C.	@ 25° C.	@ 165° C.
Component	(° C.)	(° C.)	fraction	@ 25° C.	(kg/m³)	(kg/m³)	(kg/m³)

C5-asphaltenes	—	—	0.1948	0.1655	1,210.00	1,201.93	1,119.30

3) Solvent composition:
The solvent can be one or more solvents. In this example, the solvent has the following composition:

TABLE 3

Solvent composition

			Volume	Density @	Boiling
	Carbon	Weight	fraction	15.6° C.	Point
Component	No.	fraction	@ 25° C.	(kg/m³)	(° C.)

Paraffins		0.9585	0.9583
Propane	C3	0.0002	0.0002	507.0	−42
Iso Butane	i-C4	0.0003	0.0004	562.9	−12
Normal Butane	n-C4	0.1027	0.1120	584.0	−1
Iso Pentane	i-C5	0.5652	0.5748	624.7	28
Normal Pentane	n-C5	0.1673	0.1684	631.1	36
Normal Hexane	C6	0.0490	0.0468	663.8	69
Heptanes	C7	0.0248	0.0228	688.2	98
Octanes	C8	0.0135	0.0120	707.0	126
Nonanes+	C9+	0.0243	0.0209	734.2	174
Naphthenes		0.0346	0.0288
Cyclopentane &	C5H10 &	0.0160	0.0136	750.4	49
Methylcyclopen-	C6H12
tane
Cyclohexane &	C6H12 &	0.0186	0.0152	783.5	81
Methylcyclohex-	C7H14
ane
Aromatics		0.0179	0.0129
Benzene	C6H6	0.0044	0.0031	882.9	80
Aromatics C7+	C7+	0.0135	0.0098	874.3	111

Note:
‘Nonanes+’ density/boiling point were approximated with Decane density/boiling point.
‘Cyclopentane & Methylcyclopentane’ density/boiling point were approximated with Cyclopentane density/boiling point.
‘Cyclohexane & Methylcyclohexane’ density/boiling point were approximated with Cyclohexane density/boiling point.
‘Aromatics C7+’ density/boiling point were approximated with Toluene density/boiling point.

In this example, the solvent has the following properties:

TABLE 4

Solvent density

Property	Unit	Value

Density @ 15.6° C.	kg/m³	635.15
Density @ 25° C.	kg/m³	625.47
Density @ 165° C.	kg/m³	447.61

4) The degree of asphaltene separation:
In this example, the degree of asphaltene separation is 50%, i.e. half of the asphaltenes of the bitumen will be precipitated. Asphaltenes are those compounds that are not soluble in solvent. It is assumed that these are the only insoluble compounds in the feed. As such, it is assumed that the pitch will consist only of asphaltenes.

Example 2: Calculating RI_{S+PDAO@T° C.}Using Developed Equations

As noted above, the RI of the S+PDAO can be calculated using Method 1 with the following equations:
$\begin{matrix} {RI}_{S + PDAO @ T ° C .} = {RI}_{S + {PDAO}_{0} @ T ° C .} + slope \times \frac{M_{Pitch}}{M_{Feed}^{asphaltenes}} where : & (1) \\ {RI}_{S + {PDAO}_{0} @ T ° C .} = A_{0} + (A_{1} \times {RI}_{Feed @ T ° C .} + A_{2} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{3}} & (2) \\ slope = A_{4} + (A_{5} \times {RI}_{Feed @ T ° C .} + A_{6} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{7}} & (3) \end{matrix}$
The values of A₀-A₇are determined by fitting data obtained from experimental results.
First, the RI of the feed and solvent at the operating temperature are calculated (see Ex 2.1 and 2.2, below)
Second, the RI of the S+PDAO at the extraction temperature (RI_{Stage S+PDAO@T° C.}) is calculated literature correlations (see Ex 3.3, below)
Third, the RI of the S+PDAO at the extraction temperature (RI_{Stage S+PDAO@T° C.}) is calculated using experimental results (see Ex 2.4)
Lastly, the coefficients A₀-A₇are tuned to minimize the difference between the RI of the S+PDAO at the extraction temperature calculated in the second and third steps.
Using this method, it is determined that there are three possible sets of values for A₀-A₇: 1) a first stage de-asphalting operation operating at temperatures >120° C.; 2) a first stage de-asphalting operation operating at temperatures <100° C.; and 3) a second stage de-asphalting operation as set out below:

	TABLE 5

	Stage 1

	High T (>120° C.)	Low T (<100° C.)	Stage 2

A0=	0.14953	0.14953	0.04430
A1=	−0.02996	−0.02996	0.02534
A2=	0.29936	0.29936	0.94565
A3=	0.50000	0.50000	0.00000
A4=	−0.34939	−0.34908	−0.00699
A5=	474.775	0.51249	0.00000
A6=	−419.986	−0.38067	0.00000
A7=	−2.50000	0.00000	0.00000

Based on equations (1)-(3), it is seen that RI_{Feed@T° C.}, RI_{Feed@T° C.}RI_{Solvent @T° C.}, UOP-K_Solventare determined before solving for RI_{S+PDAO @T° C.}These are calculated in Examples 2.1, 2.2 and 2.3, respectively. The RI_{S+PDAO @T° C.}is calculated in Example 2.4.

Example 2.1: Calculate RI_{Feed @T° C.}

Example 2.1.1: Calculate RI of Each Component Fractions of the Feed

Recall equation (4) above:
$\begin{matrix} \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} \times ρ_{@ T ° C .}^{- 1} = A + B \times ρ_{@ T ° C .} + C \times ρ_{@ T ° C .}^{2} & (4) \end{matrix}$
The virial coefficients, A, B and C, are determined using fitting and data analysis for a variety of hydrocarbon compounds. These are determined to be 0.4597, −0.2425, and 0.1134, respectively.
Equation (4) is modified to solve for RI with a known density:
$\begin{matrix} {RI}_{@ 25 ° C .} = \sqrt{\frac{\begin{matrix} 2 \times (0.4597 \times \frac{ρ_{@ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{@ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{@ 25 ° C .}}{1000})}^{3}) + 1 \end{matrix}}{\begin{matrix} 1 - (0.4597 \times \frac{ρ_{@ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{@ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{@ 25 ° C .}}{1000})}^{3}) \end{matrix}}} & (10) \end{matrix}$
Equation (10) is used to calculate the RI of each cut:
$\begin{matrix} {RI}_{Cut @ 25 ° C .} = \sqrt{\frac{\begin{matrix} 2 \times (0.4597 \times \frac{ρ_{Cut @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Cut @ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{Cut @ 25 ° C .}}{1000})}^{3}) + 1 \end{matrix}}{\begin{matrix} 1 - (0.4597 \times \frac{ρ_{Cut @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Cut @ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{Cut @ 25 ° C .}}{1000})}^{3}) \end{matrix}}} & (10 a) \end{matrix}$
The results are shown below (densities from Table 1, above):


	Boiling Point Cut

	Density @ 25° C.
	(kg/m³)	RI_{Cut @25° C.}

Kerosene	869.88	1.4938
Diesel	899.99	1.5118
Light Vacuum Gas Oil	937.64	1.5350
Heavy Vacuum Gas Oil	979.38	1.5617
Vacuum Residue	1,086.01	1.6378

Example 2.1.2: Calculate FRI, a Function Refractive Index, for Each Cut

Recall equation (5), above:
$\begin{matrix} F_{RI} = \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} = ρ_{@ T ° C .} (A + B \times ρ_{@ T ° C .} + C \times ρ_{@ T ° C .}^{2}) & (5) \end{matrix}$
Equation (5) is modified to calculate the F_RIof each fraction:
$\begin{matrix} F_{RI, Cut @ 25 ° C .} = \frac{{RI}_{Cut @ 25 ° C .}^{2} - 1}{{RI}_{Cut @ 25 ° C .}^{2} + 2} & (5 a) \end{matrix}$
The results are shown below (densities from Table 1, above):


	Boiling Point Cut

Density @ 25° C.
(kg/m³)	RI_{Cut @25° C.}	F_{RI, Cut @25° C.}

Kerosene	869.88	1.4938	0.2910
Diesel	899.99	1.5118	0.3000
Light Vacuum Gas	937.64	1.5350	0.3113
Oil
Heavy Vacuum Gas	979.38	1.5617	0.3241
Oil
Vacuum Residue	1,086.01	1.6378	0.3593

Example 2.1.3: Calculate F_RIfor the Entire Feed

Recall equation (6), above:
$\begin{matrix} F_{RI @ 25 ° C .} = \frac{Σ_{i} (v_{i @ 25 ° C .} \times F_{RI, i @ 25 ° C .})}{Σ_{i} v_{i @ 25 ° C .}} & (6) \end{matrix}$
Equation (6) is used to calculate the FRI of the feed composition:
$\begin{matrix} F_{RI, Feed @ 25 ° C .} = \frac{Σ_{i} (v_{{Cut}_{i} @ 25 ° C .} \times F_{RI, {Cut}_{i} @ 25 ° C .})}{Σ_{i} v_{{Cut}_{i} @ 25 ° C .}} & (6 a) \end{matrix}$
Recall:


	Boiling Point Cut

		Volume fraction
	F_{RI, Cut @25° C.}	@ 25° C.

Kerosene	0.2910	0.0252
Diesel	0.3000	0.0669
Light Vacuum Gas Oil	0.3113	0.1844
Heavy Vacuum Gas Oil	0.3241	0.1851
Vacuum Residue	0.3593	0.5384

Note:
Volume fractions from Table 1

Solving for F_{RI, Feed@25° C.}:
$F_{RI, Feed @ 25 ° C .} = \frac{Σ_{i} (v_{{Cut}_{i} @ 25 ° C .} \times F_{RI, {Cut}_{i} @ 25 ° C .})}{Σ_{i} v_{{Cut}_{i} @ 25 ° C .}}$ $F_{RI, Feed @ 25 ° C .} = \frac{\begin{matrix} v_{kerosene @ 25 ° C .} \times F_{RI, kerosene @ 25 ° C .} + \\ v_{diesel @ 25 ° C .} \times F_{RI, diesel @ 25 ° C .} + \\ v_{LVGO @ 25 ° C .} \times F_{RI, LVGO @ 25 ° C .} \end{matrix}}{\begin{matrix} v_{kerosene @ 25 ° C .} + v_{diesel @ 25 °C .} + \\ v_{LVGO @ 25 ° C .} + v_{HVGO @ 25 ° C .} + v_{VR @ 25 ° C .} \end{matrix}}$ $F_{RI, Feed @ 25 ° C .} = \frac{\begin{matrix} v_{HVGO @ 25 ° C .} \times F_{RI, HVGO @ 25 ° C .} + \\ v_{VR @ 25 ° C .} \times F_{RI, VR @ 25 ° C .} \end{matrix}}{\begin{matrix} v_{kerosene @ 25 ° C .} + v_{diesel @ 25 °C .} + \\ v_{LVGO @ 25 ° C .} + v_{HVGO @ 25 ° C .} + v_{VR @ 25 ° C .} \end{matrix}}$ $F_{RI, Feed @ 25 ° C .} = \frac{\begin{matrix} 0.00252 \times 0.2910 + 0.00669 \times 0.3000 + \\ 0.1844 \times 0.3113 + 0.1851 \times 0.3241 + 0.5384 \times \\ 0.3593 \end{matrix}}{\begin{matrix} 0.00252 + 0.00669 + 0.1844 + \\ 0.1851 + 0.5384 \end{matrix}}$ $F_{RI, Feed @ 25 ° C .} = 0.3382$

Example 2.1.4: Calculate RI for the Entire Feed

Recall equation (5):
$\begin{matrix} F_{RI} = \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} = ρ_{@ T ° C .} (A + B \times ρ_{@ T ° C .} + C \times ρ_{@ T ° C .}^{2}) & (5) \end{matrix}$
Equation (5) is re-arranged to solve for the RI:
$\begin{matrix} {RI}_{@ T ° C .} = \sqrt{\frac{2 \times F_{RI} + 1}{1 - F_{RI}}} & (11) \end{matrix}$
Equation (11) can be used to solve for the RI of the Feed @ 25° C.:
$\begin{matrix} {RI}_{Feed @ 25 ° C .} = \sqrt{\frac{2 \times F_{RI, Feed @ 25 ° C .} + 1}{1 - F_{RI, Feed @ 25 ° C .}}} & (11 a) \\ Where F_{RI, Feed @ 25 ° C .} = 0.3382 & (Ex 2.1 .3) \end{matrix}$
Solving for RI_{Feed @25° C.}:
${RI}_{Feed @ 25 ° C .} = \sqrt{\frac{2 \times F_{RI, Feed @ 25 ° C .} + 1}{1 - F_{RI, Feed @ 25 ° C .}}} = \sqrt{\frac{2 \times 0.3382 + 1}{1 - 0.3382}} = 1.5917$

Example 2.1.5 Calculate RI at the Operating Temperature

Recall equation (7):
$\begin{matrix} \frac{{RI}_{@ T ° C .}^{2} - 1}{{RI}_{@ T ° C .}^{2} + 2} = \frac{{RI}_{@ T_{0} ° C .}^{2} - 1}{{RI}_{@ T_{0} ° C .}^{2} + 2} \times \frac{ρ_{@ T ° C .}}{ρ_{@ T_{0} ° C .}} & (7) \end{matrix}$
Equation (7) is rearranged to solve for the RI of a new temperature given a reference temperature of 25° C.:
$\begin{matrix} {RI}_{@ T ° C .} = \sqrt{\frac{2 \times \frac{{RI}_{@ 25 ° C .}^{2} - 1}{{RI}_{@ 25 ° C .}^{2} + 2} \times \frac{ρ_{@ T ° C .}}{ρ_{@ 25 ° C .}} + 1}{1 - \frac{{RI}_{@ 25 ° C .}^{2} - 1}{{RI}_{@ 25 ° C .}^{2} + 2} \times \frac{ρ_{@ T ° C .}}{ρ_{@ 25 ° C .}}}} & (12) \end{matrix}$
Recall (from Table 1):


	Boiling Point Cut

	Density @ 25° C.	Density @ 165° C.
	(kg/m³)	(kg/m³)

	Total (Bitumen)	1,021.03	932.45

Solving for RI of the feed at the operating temperature:
${RI}_{Feed @ 165 ° C .} = \sqrt{\frac{2 \times \frac{{RI}_{Feed @ 25 ° C .}^{2} - 1}{{RI}_{Feed @ 25 ° C .}^{2} + 2} \times \frac{ρ_{feed @ 165 ° C .}}{ρ_{Feed @ 25 ° C .}} + 1}{1 - \frac{{RI}_{Feed @ 25 ° C .}^{2} - 1}{{RI}_{Feed @ 25 ° C .}^{2} + 2} \times \frac{ρ_{feed @ 165 ° C .}}{ρ_{Feed @ 25 ° C .}}}} = \sqrt{\frac{2 \times \frac{{1.5917}^{2} - 1}{{1.5917}^{2} + 2} \times \frac{932.46}{1021.03} + 1}{1 - \frac{{1.5917}^{2} - 1}{{1.5917}^{2} + 2} \times \frac{932.46}{1021.03}}} = 1.5300$

Example 2.2: Calculate RI_{Solvent@T° C.}(Using Same Method as the Feed)

RI_{S @165° C.}=1.2477

Example 2.3: Calculate UOP-K_Solvent

Example 2.3.1: Calculate UOP-K for Each Component in the Solvent

Recall equation (8):
$\begin{matrix} UOP - K = \frac{\sqrt[3]{BP \times 1.8 + 492}}{\frac{ρ_{@ 15.6 ° C .}}{1000}} & (8) \end{matrix}$
Solving for each component of the solvent (using density and boiling point from Table 3, above):


		Boiling	Density @
	Carbon	Point	15.6° C.
Component	No.	(° C.)	(kg/m³)	UOP-K_i

Paraffins
Propane	C3	−42	507.0	14.73
Iso Butane	i-C4	−12	562.9	13.82
Normal Butane	n-C4	−1	584.0	13.51
Iso Pentane	i-C5	28	624.7	13.05
Normal Pentane	n-C5	36	631.1	13.04
Normal Hexane	C6	69	663.8	12.82
Heptanes	C7	98	688.2	12.71
Octanes	C8	126	707.0	12.67
Nonanes+	C9+	174	734.2	12.67
Naphthenes
Cyclopentane &	C5H10 &	49	750.4	11.11
Methylcyclopentane	C6H12
Cyclohexane &	C6H12 &	81	783.5	10.98
Methylcyclohexane	C7H14
Aromatics
Benzene	C6H6	80	882.9	9.74
Aromatics C7+	C7+		111	874.3	10.11

Example 2.3.2: Calculate UOP-K for the Combined Solvent

Recall equation (9)
UOP-K=Σ_i(w _i×UOP-K_i) (9)
Using the weight fractions from Table 2 and the UOP-K's calculated in the previous step:
UOP-K_Solvent=Σ_i(w _i×UOP-K_i)=
UOP-K_Solvent=(w _C3×UOP-K_C3 w _iC4×UOP-K_iC4 +. . . +w _{Aromatics C7+}×UOP-K_{Aromatics C7+}
UOP-K_Solvent=(0.0002×14.73+0.0003×13.82+. . . +0.0135×10.11=
UOP-K_Solvent=12.94

Example 2.4: Calculate RI of the S+PDAO at 165° C. Using Method 1

Recall:
The degree of asphaltene separation is selected to be 0.5
$\begin{matrix} (i . e . \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}} = 0.5) & (Ex . 1) \end{matrix}$
The values of A₀-A₇are found in Table 1, using the values for stage 1 and temperatures of above 120° C.
The values of RI_Feed, RI_Solvent, and UOP-K_Solventwere calculated above (Ex 2.1, 2.2, and 2.3)

Example 2.4.1 Calculate RI_S+PDAO ₀ _{@165° C.}

Solve for RI_S+PDAO ₀ _{@165° C.}using equation (2):
RI_S+PDAO ₀ _{@165° C.} =A ₀+(A ₁×RI_{Feed@165° C.} +A ₂×RI_{Solvent@165° C.})×UOP-K_Solvent ^A ³
RI_S+PDAO ₀ _{@165° C.}=0.14953+(−0.02996×1.5300+0.299936×1.2477)×12.94^0.5
RI_S+PDAO ₀ _{@165° C.}==1.3281 (2)

Example 2.4.2 Calculate Slope

Solve for slope using equation (3)
slope=A ₄+(A ₅×RI_{Feed@165° C.} +A ₆×RI_{Solvent@165° C.})×UOP-K_Solvent ^A ⁷
slope=−0.34939+(474.775×1.5300|419.986×1.2477)×12.94^−2.5
slope=−0.0133 (3)

Example 2.4.2 Calculate RI_{S+PDAO@165° C.}

Solve for RI_{S+PDAO@165° C.}, using equation (1):
$\begin{matrix} {RI}_{S + PDAO @ 165 ° C .} = {RI}_{S + {PDAO}_{0} @ 165 ° C .} + slope \times \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}} {RI}_{S + PDAO @ 165 ° C .} = 1.3281 - 0.0133 \times 0.5 {RI}_{S + PDAO @ 165 ° C .} = 1.3215 & (1) \end{matrix}$

Example 3: Calculating RI_S+PDAOUsing Correlations from the Literature and Mass Balances

The RI_S+PDAOis calculated using correlations from the literature and mass balances (Method 2). This calculated value will be compared to the RI_S+PDAOcalculated in Ex 2 using Method 1. The convergence of these values is used to control the S/F ratio (Ex 4).
Equation (12) is re-arranged to solve for RI of the S+PDAO:
$\begin{matrix} {RI}_{S + PDAO @ T ° C .} = \sqrt{\frac{2 \times \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ T ° C .}}{ρ_{S + PDAO @ 25 ° C .}} + 1}{1 - \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ T ° C .}}{ρ_{S + PDAO @ 25 ° C .}}}} & (12 b) \end{matrix}$
The values of ρ_{S+PDAO @25° C.}, ρ_{S+PDAO @T° C.}and RI_{S+PDAO @25° C.}are calculated first (Ex 3.2, 3.3) before calculating RI_{S+PDAO @T° C.}(Ex 3.3).

Example 3.1 Guess the S/F Ratio

The S/F ratio is the operational parameter being controlled (see Ex 1). This value will affect the equilibrium of the streams (e.g. the densities of the pitch and S+PDAO will be affected).
Start with an initial guess for the S/F ratio. In this example, the initial guess is:

- S/F=1.20

Where

S/F: S/F Ratio (on weight basis).

Example 3.1.1 Calculate the Weight % (on Feed Basis) of Solvent

By applying a mass balance:
w _Solvent =w _Feed×(S/F) (13)

Where:

w_Solvent: Weight % (on Feed basis) of Solvent;
w_Feed: Weight % (on Feed basis) of Feed (i.e. 100, by definition); and
S/F: Solvent to Feed Ratio (on weight basis).
Solving:
w _Solvent =w _Feed×(S/F)=100*1.20=120 wt %

Example 3.2 Calculate ρ_{S+PDAO @25° C.}, ρ_{S+PDAO @T° C.}

Example 3.2.1 Calculate the Density of the Pitch

Recall from Ex. 1, that the pitch consists of C5-asphaltenes. It follows that the density of the pitch is equal to the density of the C5-asphaltenes:
ρ_{Pitch@T° C.}=ρ_{C5−asphaltenes@T° C.} (14)
Recall from Table 2:


	Density @	Density @	Density @
	15.6° C.	25° C.	165° C.
Component	(kg/m³)	(kg/m³)	(kg/m³)

C5-asphaltenes	1,210.00	1,201.93	1,119.30

Example 3.2.2 Calculate the Weight % (on Feed Basis) of Pitch

Since the pitch is the portion of the C5-asphaltenes removed from the feed:
$\begin{matrix} w_{Pitch} = w_{Feed}^{C 5 - asphaltenes} \times \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}} & (15) \end{matrix}$

Where:

- w_Pitch: Weight % (on Feed basis) of Pitch after phase separation has occurred;
- w_Feed ^{C5-asphaltenes}: Weight % (on Feed basis) of C5-asphaltenes in the Feed. (Table 1);
- M_Pitch: Mass of pitch after phase separation has occurred; and
- M_Feed ^{C5-asphaltenes}: Mass of C5-asphaltenes in the Feed.

Solving for w_Pitch:
$w_{Pitch} = w_{Feed}^{C 5 - asphaltenes} \times \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}} = 19.48 \times 0.5 = 9.74 wt %$
Since the partially de-asphalted oil will be the portion of the feed after the removal of the pitch:
w _PDAO =w _Feed −w _Pitch (16)

Where

- w_PDAO: Weight % (on Feed basis) of partially de-asphalted oil after phase separation has occurred;
- w_Feed: Weight % (on Feed basis) of Feed (i.e. 100, by definition); and
- w_Pitch: Weight % (on Feed basis) of Pitch after phase separation has occurred (Ex 3.2.2).

Solving:
w _PDAO =w _Feed −w _Pitch=100−9.74=90.26 wt %

Example 3.2.4 Calculate the Density of the PDAO

The density of the partially de-asphalted oil can be calculated as follows:
$\begin{matrix} ρ_{PDAO @ T ° C .} = \frac{w_{PDAO}}{\frac{w_{Feed}}{ρ_{Feed @ T ° C .}} - \frac{w_{Pitch}}{ρ_{Pitch @ T ° C .}}} & (17) \end{matrix}$

Where

- ρ_{PDAO @T° C.}: Density of the partially de-asphalted oil at a specified temperature, after phase separation has occurred, in kg/m³;
- w_PDAO: Weight % (on Feed basis) of partially de-asphalted oil, after phase separation has occurred (Ex. 3.2.3);

w_Feed: Weight % (on Feed basis) of the Feed (i.e. 100, by definition); ρ_{Feed @T° C.}: Density of the Feed at a specified temperature, in kg/m³(Table 1); w_Pitch: Weight % (on Feed basis) of the Pitch, after phase separation has occurred (Ex 3.2.2); and ρ_{Pitch @T° C.}: Density of the Pitch at a specified temperature, after phase separation has occurred, in kg/m³(Ex. 3.2.1).
Solving for density at 25° C. and operating temperature (165° C.):
$ρ_{PDAO @ 25 ° C .} = \frac{w_{PDAO}}{\frac{w_{Feed}}{ρ_{Feed @ 25 ° C .}} - \frac{w_{Pitch}}{ρ_{Pitch @ 25 ° C .}}} = \frac{90.26}{\frac{100}{1021.04} - \frac{9.74}{1, 201.93}} = 1, 004.72 \frac{kg}{m^{3}}$ $ρ_{PDAO @ 165 ° C .} = \frac{w_{PDAO}}{\frac{w_{Feed}}{ρ_{Feed @ 165 ° C .}} - \frac{w_{Pitch}}{ρ_{Pitch @ 165 ° C .}}} = \frac{90.26}{\frac{100}{932.46} - \frac{9.74}{1, 119.30}} = 915.96 \frac{kg}{m^{3}}$

Example 3.2.5 Calculating the Weight of the Solvent in the Pitch+Solvent Phase

Based on experimental data, the weight fraction of solvent in the Pitch+Solvent, after phase separation is determined to be correlated with the density of pitch at the extraction temperature according to the following formula:
$\begin{matrix} w_{Pitch + S}^{Solvent} = - 1.29195 \times (\frac{ρ_{Pitch @ T ° C .}}{1000}) + 1.86145 & (18) \end{matrix}$

Where:

- w_Pitch+S ^Solvent: weight fraction of solvent in the Pitch+Solvent, after phase separation has occurred; and
- ρ_{Pitch @T° C.}: density of pitch at the extraction temperature, in kg/m³(Ex 3.2.1).

Solving for w_Pitch+S ^Solvent:

- w_Pitch+S ^Solvent=−1.29195×ρ_{Pitch@165° C.}+1.86145
- w_Pitch+S ^Solvent=−1.29195×(1.11930)+1.86145
- w_Pitch+S ^Solvent=41.54 wt %

Example 3.2.6 the Weight % (on Feed Basis) of Pitch+S

By applying a mass balance:
$\begin{matrix} w_{Pitch + S} = \frac{w_{Pitch}}{100 - w_{Pitch + S}^{Solvent}} & (19) \end{matrix}$

Where

- w_Pitch+S: Weight % (on Feed basis) of pitch-solvent;
- w_Pitch: Weight % (on Feed basis) of Pitch (Example 3.2.4); and
- w_Pitch+S ^Solvent: Weight % (on Pitch+S basis) of Solvent in pitch-solvent (Ex. 3.2.5).

Solving:
$w_{Pitch + S} = \frac{w_{Pitch}}{100 - w_{Pitch + S}^{Solvent}} = \frac{9.74}{1 - 41.54} = 16.66 wt %$

Example 3.2.7 Calculate the Density of the Pitch+Solvent

The density of the pitch-solvent can be calculated as follows:
$\begin{matrix} ρ_{Pitch + S @ 25 ° C .} = \frac{w_{Pitch + S}}{\frac{w_{Pitch + S} - w_{Pitch}}{ρ_{S @ 25 ° C .}} + \frac{w_{Pitch}}{ρ_{Pitch @ 25 ° C .}}} & (20) \end{matrix}$

Where

- ρ_{Pitch+S @25° C.}: Density of the pitch-solvent at 25° C., after phase separation has occurred, in kg/m³;
- w_Pitch+S: Weight % (on Feed basis) of pitch-solvent after phase separation has occurred (Ex 3.2.6);
- w_Pitch: Weight % (on Feed basis) of Pitch, after phase separation has occurred (Ex 3.2.2);
- ρ_{S @25° C.}: Density of the Solvent at 25° C., in kg/m³(Table 4); and ρ_{Pitch @25° C.}: Density of the Pitch at 25° C., after phase separation has occurred, in kg/m³(Ex 3.2.1).

Solving:
$ρ_{Pitch + S @ 25 ° C .} = \frac{w_{Pitch + S}}{\frac{w_{Pitch + S} - w_{Pitch}}{ρ_{S @ 25 ° C .}} + \frac{w_{Pitch}}{ρ_{Pitch @ 25 ° C .}}} = \frac{16.66}{\frac{16.66 - 9.74}{625.47} + \frac{9.74}{1, 201.93}} = 869.19 \frac{kg}{m^{3}}$

Example 3.2.8 Calculate the Weight % (on Feed Basis) of the S+PDAO

The weight of the S+PDAO phase can be calculated by a mass balance:
w _S+PDAO =w _Feed +w _Solvent −w _Pitch+S (21)

Where

- w_S+PDAO: Weight % (on Feed basis) of S+PDAO, after phase separation has occurred;
- w_Feed: Weight % (on Feed basis) of Feed (i.e. 100, by definition);
- w_Solvent: Weight % (on Feed basis) of Solvent (Ex 3.1.1); and w_Pitch+S: Weight % (on Feed basis) of pitch-solvent, after phase separation has occurred (Ex. 3.2.6).

Solving:
w _S+PDAO =w _Feed +w _solvent −w _Pitch+S=100+120−16.66
w _S+PDAO=203.33 wt %

Example 3.2.9 Calculate the Density of the S+PDAO at 25° C. and at the Extraction Temperature

The density of the S+PDAO phase
$\begin{matrix} ρ_{S + PDAO @ T ° C .} = \frac{w_{S + PDAO}}{\frac{w_{S + PDAO} - w_{PDAO}}{ρ_{S @ T ° C .}} + \frac{w_{PDAO}}{ρ_{PDAO @ T ° C .}}} & (22) \end{matrix}$
Where

- ρ_{S+PDAO @T° C.}: Density of the S+PDAO at the operating temperature in ° C., after phase separation has occurred, in kg/m³;
- w_S+PDAO: Weight % (on Feed basis) of S+PDAO after phase separation has occurred (Ex 3.2.8);
- w_PDAO: Weight % (on Feed basis) of partially de-asphalted oil after phase separation has occurred (Ex 3.2.3);
- ρ_{S@T° C.}: Density of the solvent at the specified temperature in ° C., in kg/m³(Table 4); and
- ρ_{PDAO @T° C.}: Density of the partially de-asphalted oil at the specified temperature in ° C., after phase separation has occurred, in kg/m³(Ex 6.2.4).

Solving for density of the S+PDAO at a reference temperature and the operating temperature:
$ρ_{S + PDAO @ 25 ° C .} = \frac{w_{S + PDAO}}{\frac{w_{S + PDAO} - w_{PDAO}}{ρ_{S @ 25 ° C .}} + \frac{w_{PDAO}}{ρ_{PDAO @ 25 ° C .}}} = \frac{203.33}{\frac{203.33 - 90.26}{625.47} + \frac{90.26}{1, 004.72}} = 751.37 \frac{kg}{m^{3}}$ $ρ_{S + PDAO @ 165 ° C .} = \frac{w_{S + PDAO}}{\frac{w_{S + PDAO} - w_{PDAO}}{ρ_{S @ 165 ° C .}} + \frac{w_{PDAO}}{ρ_{PDAO @ 165 ° C .}}} = \frac{203.33}{\frac{203.33 - 90.26}{447.61} + \frac{90.26}{915.96}} = 579.03 \frac{kg}{m^{3}}$

Example 3.3 Calculate RI_{S+PDAO@T° C.}

Example 3.3.1 the Volume % of Pitch (on Feed Basis) at 25° C.

$\begin{matrix} v_{Pitch @ 25 ° C .} = \frac{w_{Pitch} * 100}{ρ_{Pitch @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} & (23) \end{matrix}$
Where

- v_{Pitch @25° C.}: Volume % (on Feed basis) of Pitch at 25° C., after phase separation has occurred;
- w_Pitch: Weight % (on Feed basis) of Pitch, after phase separation has occurred (Ex 3.2.2);
- ρ_{Pitch @25° C.}: Density of the Pitch at 25° C. in kg/m³, after phase separation has occurred (Ex 3.2.1);
- w_i,F: Weight % (on Feed basis) of a Feed boiling point cut (Table 1); and
- ρ_{i,F @ 25° C.}: Density of a Feed boiling point cut at 25° C., in kg/m³(Table 1).

Solving:
$Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}} = \frac{w_{190 - 260 ° C ., F}}{ρ_{190 - 260 ° C ., F @ 25 ° C .}} + \frac{w_{260 - 343 ° C ., F}}{ρ_{260 - 343 ° C ., F @ 25 ° C .}} + \frac{w_{343 - 454 ° C ., F}}{ρ_{343 - 454 ° C ., F @ 25 ° C .}} + \frac{w_{454 - 560 ° C ., F}}{ρ_{454 - 560 ° C ., F @ 25 ° C .}} + \frac{w_{560 - 820 ° C ., F}}{ρ_{560 - 820 ° C . F @ 25 ° C .}}$ $Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}} = \frac{2.15}{869.88} + \frac{5.89}{899.99} + \frac{16.93}{937.64} + \frac{17.76}{979.38} + \frac{57.27}{1086.01}$ $Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}} = 0.0979$ $v_{Pitch @ 25 ° C .} = \frac{w_{Pitch} * 100}{ρ_{Pitch @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} = \frac{9.74 * 100}{1, 201.93 * 0.0979} = 8.27 vol %$

Example 3.3.2 Calculate the Volume % of Solvent (on Feed Basis) at 25° C.

The volume of solvent can be calculated as follows:
$\begin{matrix} v_{Solvent @ 25 ° C .} = \frac{w_{Solvent} * 100}{ρ_{Solvent @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} & (24) \end{matrix}$

Where

- v_{Solvent @25° C.}: Volume % (on Feed basis) of Solvent at 25° C., after phase separation has occurred;
- w_Solvent: Weight % (on Feed basis) of Solvent, after phase separation has occurred (Ex 3.1.1);
- ρ_{Solvent @25° C.}: Density of the Solvent at 25° C., in kg/m³(Table 3);
- w_i,F: Weight % (on Feed basis) of a Feed boiling point cut (Table 1); and
- ρ_{i,F @ 25° C.}: Density of a Feed boiling point cut at 25° C., in kg/m³(Table 1).

Recall,
$Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}} = 0.0979$

(Example 3.3.1).

Solving:
$v_{Solvent @ 25 ° C .} = \frac{w_{Solvent} * 100}{ρ_{Solvent @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} = \frac{120 * 100}{625.47 * 0.0979} = 195.88 vol %$

Example 3.3.3 Calculate the Volume % of Pitch+S (on Feed Basis) at 25° C.

The volume of pitch-solvent can be calculated as follows:
$\begin{matrix} v_{Pitch + S @ 25 ° C .} = \frac{w_{Pitch + S} * 100}{ρ_{Pitch + S @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} & (25) \end{matrix}$

Where

- v_{Pitch+S@25° C.}: Volume % (on Feed basis) of pitch-solvent at 25° C., after phase separation has occurred;
- w_Pitch+S: Weight % (on Feed basis) of pitch-solvent, after phase separation has occurred (Ex 3.2.6);
- ρ_{Pitch+S@25° C.}: Density of the pitch-solvent at 25° C., in kg/m³(Ex 3.2.7);
- w_i,F: Weight % (on Feed basis) of a Feed boiling point cut (Table 1); and
- ρ_{i,F @ 25° C.}: Density of a Feed boiling point cut at 25° C., in kg/m³(Table 1).

Recall,
$Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}} = 0.0979$

(Ex 3.3.1).

Solving:
$v_{Pitch + S @ 25 ° C .} = \frac{w_{Pitch + S} * 100}{ρ_{Pitch + S @ 25 ° C .} * Σ_{i} \frac{w_{i, F}}{ρ_{i, F @ 25 ° C .}}} = \frac{16.66 * 100}{869.19 * 0.0979} = 19.57 vol %$

Example 3.3.4 the Volume % of PDAO (on Feed Basis) at 25° C.

The volume % of PDAO (on Feed basis) at 25° C. is calculated via a mass balance:
v _{PDAO@25° C.} =v _{Feed@25° C.} −v _{Pitch@25° C.} (26)

Where

- v_{PDAO @25° C.}: Volume % (on Feed basis) of partially de-asphalted oil at 25° C., after phase separation has occurred.
- v_Feed@25° C.: Volume % (on Feed basis) of Feed at 25° C. (i.e. 100, by definition) v_{Pitch @25° C.}: Volume % (on Feed basis) of Pitch at 25° C., after phase separation has occurred. (Ex 3.3.1)

Solving:
v _{PDAO@25° C.} =v _{Feed@25° C.} −v _{Pitch@25° C.}=100−8.27=91.72 vol %

Example 3.3.5 Calculate the Volume % of S+PDAO (on Feed Basis) at 25° C.

The volume of S+PDAO (on feed basis) at 25° C. is calculated via a mass balance:
v _S+PDAO@25° C.=v _{Feed@25° C.} +v _{Solvent@25° C.} −v _{Pitch+S@25° C.} (27)

Where:

- v_{S+PDAO @25° C.}: Volume % (on Feed basis) of solvent-partially de-asphalted oil at 25° C., after phase separation has occurred.
- v_{Feed@25° C.}: Volume % (on Feed basis) of Feed at 25° C. (i.e. 100, by definition)
- v_{Solvent @25° C.}: Volume % (on Feed basis) of Solvent at 25° C. (Ex 3.3.3)
- v_{Pitch+S @25° C.}: Volume % (on Feed basis) of pitch-solvent at 25° C., after phase separation has occurred. (Ex 3.3.4)

Solving:
Volume % of S+PDAO (on Feed basis) at 25° C.
v _{S+PDAO@25° C.} =v _{Feed@25° C.} +v _{Solvent@25° C.} −v _{Pitch+S@25° C.}
v _{S+PDAO@25° C.}=100+195.88−19.57
v _{S+PDAO@25° C.}=276.31 vol %

Example 3.3.6 Calculate RI of Pitch

Equation (10) is used to calculate the RI of pitch @ 25° C.:
$\begin{matrix} {RI}_{Pitch @ 25 ° C .} = \sqrt{\frac{\begin{matrix} 2 \times (0.4597 \times \frac{ρ_{Pitch @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{2} + 0.1134 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{3}) + 1 \end{matrix}}{\begin{matrix} 1 - (0.4597 \times \frac{ρ_{Pitch @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{3}) \end{matrix}}} & (10 b) \end{matrix}$

Where:

- RI_{Pitch@25° C.}: Refractive index of the Pitch at 25° C.; and ρ_{Pitch @25° C.}: Density of the Pitch at 25° C., in kg/m³. (Ex 3.2.1).

Solving:
${RI}_{Pitch @ 25 ° C .} = \sqrt{\frac{\begin{matrix} 2 \times (0.4597 \times \frac{ρ_{Pitch @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{2} + 0.1134 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{3}) + 1 \end{matrix}}{\begin{matrix} 1 - (0.4597 \times \frac{ρ_{Pitch @ 25 ° C .}}{1000} - 0.2425 \times \\ {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{2} + 0.1134 \times {(\frac{ρ_{Pitch @ 25 ° C .}}{1000})}^{3}) \end{matrix}}} = {RI}_{Pitch @ 25 ° C .} = \sqrt{\frac{\begin{matrix} 2 \times (0.4597 \times \frac{1201.93}{1000} - 0.2425 \times \\ {(\frac{1201.93}{1000})}^{2} + 0.1143 \times {(\frac{1201.93}{1000})}^{3}) + 1 \end{matrix}}{\begin{matrix} 1 - (0.4597 \times \frac{1201.93}{1000} - 0.2425 \times \\ {(\frac{1201.93}{1000})}^{2} + 0.1143 \times {(\frac{1201.93}{1000})}^{3}) \end{matrix}}}$ ${RI}_{Pitch @ 25 ° C .} = 1.7299$

Example 3.3.7 Calculate F_RIof Pitch

Solving equation (5) for F_RI _{Pitch @25° C.}:
$\begin{matrix} F_{{RI}_{Pitch @ 25 ° C .}} = \frac{{({RI}_{Pitch @ 25 ° C .})}^{2} - 1}{{({RI}_{Pitch @ 25 ° C .})}^{2} + 2} & (5 b) \end{matrix}$

Where

- F_RI _{Pitch @25° C.}: F_RIof the Pitch at 25° C.; and
- RI_{Pitch @25° C.}: Refractive index of the Pitch at 25° C. (Ex 3.3.1).

Solving:
$F_{{RI}_{Pitch @ 25 ° C .}} = \frac{{({RI}_{Pitch @ 25 ° C .})}^{2} - 1}{{({RI}_{Pitch @ 25 ° C .})}^{2} + 2} = \frac{{1.7299}^{2} - 1}{{1.7299}^{2} + 2} = 0.3991$

Example 3.3.8 Calculate the F_RIof the PDAO at 25° C.

Recall equation (6) and solving for F_RIof the partially deasphalted oil:
$\begin{matrix} F_{RI, PDAO @ 25 ° C .} = \frac{v_{Feed @ 25 ° C .} \times F_{{RI}_{Feed @ 25 ° C .}} - v_{Pitch @ 25 ° C .} \times F_{{RI}_{Pitch @ 25 ° C .}}}{v_{PDAO @ 25 ° C .}} & (6 b) \end{matrix}$

Where

- F_{RI,PDAO @25° C.}: F_RIof the partially de-asphalted oil at 25° C., after phase separation has occurred;
- v_{Feed@25° C.}: Volume % (on Feed basis) of Feed at 25° C. (i.e. 100, by definition)
- F_RI _{Feed @25° C.}: F_RIof the Feed at 25° C. (Ex 2.1.3);
- v_{Pitch @25° C.}: Volume % (on Feed basis) of Pitch at 25° C., after phase separation has occurred (Ex 3.3.3);
- F_RI _{Pitch @25° C.}: F_RIof the Pitch at 25° C., after phase separation has occurred (Ex 3.3.2); and
- v_{PDAO@25° C.}: Volume % (on Feed basis) of partially de-asphalted oil at 25° C., after phase separation has occurred (Ex 3.3.4).

Solving:
$F_{RI, PDAO @ 25 ° C .} = \frac{v_{Feed @ 25 ° C .} \times F_{{RI}_{Feed @ 25 ° C .}} - v_{Pitch @ 25 ° C .} \times F_{{RI}_{Putch @ 25 ° C .}}}{v_{PDAO @ 25 ° C .}} = F_{RI, PDAO @ 25 ° C .} = \frac{100 \times 0.3382 - 8.27 \times 0.3991}{91.72}$ $F_{RI, PDAO @ 25 ° C .} = 0.3328$

Example 3.3.9 Calculate F_RIof the S+PDAO at 25° C.

Re-arranging equation (6):
F _{RI,S+PDAO@25° C.}=(v _{S+PDAO@25° C.} −v _{PDAO@25° C.})×F _{RI,S@25° C.} +v _{PDAO@25° C.} ×F _{RI,PDAO@25° C.} (28)

Where:

- F_{RI,S+PDAO @25° C.}: F_RIvalue of the solvent-partially de-asphalted oil at 25° C., after phase separation has occurred;
- v_{S+PDAO @25° C.}: Volume % (on Feed basis) of solvent-partially de-asphalted oil at 25° C., after phase separation has occurred (Ex 3.3.7);
- v_{PDAO @25° C.}: Volume % (on Feed basis) of solvent at 25° C. (Ex 3.3.3);
- F_{RI,S@25° C.}: F_RIvalue of the solvent at 25° C. (within the calculation of Ex 2.2); and
- F_{RI,PDAO@25° C.}: F_RIvalue of the partially de-asphalted oil at 25° C., after phase separation has occurred (Ex 3.3.8).
- Solving:

F_RIof the S+PDAO at 25° C.:
F _{RI,S+PDAO@25° C.}=(v _{S+PDAO@25° C.} −v _{PDAO@25° C.})×F _{RI,S@25° C.} +v _{PDAO@25° C.} ×F _{RI,S+PDAO@25° C.}
F _{RI S+PDAO@25° C.}=(276.31−91.72)×0.2187+91.72×0.3328F _{RI,S+PDAO@25° C.}=0.2566

Example 3.3.10 Calculate the RI of the S+PDAO at 25° C.

Equation (11) from Ex 2.1.4 is used to solve the for RI_{S+PDAO@25° C.}:
$\begin{matrix} {RI}_{S + PDAO @ 25 ° C .} = \sqrt{\frac{2 \times F_{RI, S + PDAO @ 25 ° C .} + 1}{1 - F_{RI, S + PDAO @ 25 ° C .}}} & (11 b) \end{matrix}$

Where:

- RI_{S+PDAO@25° C.}: RI of the S+PDAO at 25° C., after phase separation has occurred; and
- F_{RI,S+PDAO@25° C.}: F_RIof the S+PDAO at 25° C., after phase separation has occurred (Ex 3.3.9).

Solving:
RI of the S+PDAO at 25° C.
${RI}_{S + PDAO @ 25 ° C .} = \sqrt{\frac{2 \times F_{RI, S + PDAO @ 25 ° C .} + 1}{1 - F_{RI, S + PDAO @ 25 ° C .}}} = \sqrt{\frac{2 \times 0.2566 + 1}{1 - 0.2566}} = 1.4267$

Example 3.3.11 Calculate the RI of the S+PDAO at the Extraction Temperature

Equation (12) from Ex 2.1.5 can be used to calculate RI_{S+PDAO @T° C.}:
$\begin{matrix} {RI}_{S + PDAO @ T ° C .} = \sqrt{\frac{2 \times \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ T ° C .}}{ρ_{S + PDAO @ 25 ° C .}} + 1}{1 - \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ T ° C .}}{ρ_{S + PDAO @ 25 ° C .}}}} & (10 b) \end{matrix}$

Where:

- RI_{S+PDAO @T° C.}: RI of the S+PDAO at the extraction temperature, after phase separation has occurred;
- RI_{S+PDAO @25° C.}: RI of the S+PDAO at 25° C., after phase separation has occurred (Ex 3.3.9);
- ρ_{S+PDAO @25° C.}: Density of the S+PDAO at 25° C., after phase separation has occurred, in kg/m³(Ex 3.2.9); and ρ_{S+PDAO @T° C.}: Density of the S+PDAO at the extraction temperature, after phase separation has occurred, in kg/m³(Ex 3.2.9).

Solving:
${RI}_{S + PDAO @ 165 ° C .} = \sqrt{\frac{2 \times \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ 165 ° C .}}{ρ_{S + PDAO @ 25 ° C .}} + 1}{1 - \frac{{RI}_{S + PDAO @ 25 ° C .}^{2} - 1}{{RI}_{S + PDAO @ 25 ° C .}^{2} + 2} \times \frac{ρ_{S + PDAO @ 165 ° C .}}{ρ_{S + PDAO @ 25 ° C .}}}} = \sqrt{\frac{2 \times \frac{{1.4267}^{2} - 1}{{1.4267}^{2} + 2} \times \frac{579.03}{751.37} + 1}{1 - \frac{{1.4267}^{2} - 1}{{1.4267}^{2} + 2} \times \frac{579.03}{751.37}}} = 1.3189$

Example 4 Check Whether the Two Methods of Calculating the RI of S+PDAO at the Extraction Temperature have Converged

Recall, the RI of the S+PDAO calculated in Ex 2 and 3 are:
RI_{Stage 1 S+PDAO @165° C.} ^{Method 1}=1.3215 (Ex 2.4)
RI_{Stage 1 S+PDAO @165° C.} ^{Method 2}=1.3189 (Ex 3.3.11)
Since RI_{Stage 1 S+PDAO @165° C.} ^{Method 2}≠RI_{Stage 1 S+PDAO @165° C.} ^{Method 1}, Ex 3 is iterated using new guesses until the RI values converge.
RI_{Stage 1 S+PDAO @165° C.} ^{Method 2}<RI_{Stage 1 S+PDAO @165° C.} ^{Method 1}, the guessed S/F Ratio in Ex 3 is decreased.
RI_{Stage 1 S+PDAO @165° C.} ^{Method 2}>RI_{Stage 1 S+PDAO @165° C.} ^{Method 1}, the guessed S/F Ratio in Ex 3 is increased.
The guessed value of the selected operating parameter at the convergence of the RI values calculated using Method 1 and Method 2 is the controlled value of the selected operating parameter.
The above description is meant to be exemplary only, and one skilled in the relevant arts will recognize that changes may be made to the embodiments described without departing from the scope of the disclosure. For example, the operations represented in the drawing described herein are for purposes of example only. There may be many variations to these operations without departing from the teachings of the present disclosure. For instance, the operations may be performed in a differing order, or operations may be added, deleted, or modified. The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. Also, one skilled in the relevant arts will appreciate that while the systems, devices and assemblies disclosed and shown herein may comprise a specific number of elements/components, the systems, devices and assemblies could be modified to include additional or fewer of such elements/components. The present disclosure is also intended to cover and embrace all suitable changes in technology. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the scope of the appended claims.
Every document, including publications and published patent documents, cited herein is hereby incorporated herein by reference in its entirety. The citation of any document is not an admission that it is prior art with respect to the present disclosure. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

Claims

What is claimed is:

1. A method for solvent de-asphalting comprising:

selecting a solvent based on RI; and

contacting the selected solvent with a feed including asphaltenes to effect de-asphalting.

2. A de-asphalting system for solvent de-asphalting comprising:

a deasphalter, the deasphalter defining:

a contacting zone for contacting a feed, including asphaltenes, and a solvent to form a mixture, wherein the contacting of the feed and the solvent causes at least a portion of the asphaltenes to precipitate out of the mixture, the contacting disposed at an operating temperature; and

a separation zone to separate the mixture into a de-asphalted oil-comprising material fraction (“S+PDAO”) and a asphaltene-rich material fraction, the asphaltene-rich material fraction including the precipitated asphaltenes; and

a controller for controlling at least one operating parameter of the deasphalter based on at least on a refractive index of the S+PDAO phase, the operating parameter selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the mass of precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the mass of the solvent to the mass of the feed.

3. The de-asphalting system of claim 2 further comprising at least one flow regulator operatively connected to the controller, such that the controller, via the flow regulator, controls the feed flow rate of the feed, a solvent flow rate of the solvent or both.

4. The de-asphalting system of claim 2 further comprising a temperature regulator operatively connected to the controller, such that the controller, via the temperature regulator, controls the operating temperature of the contacting zone.

5. The de-asphalting system of claim 2 further comprising a refractive index determining device operatively connected to the controller.

6. The de-asphalting system of claim 5, wherein the refractive index determining device includes a densitometer, wherein the densitometer is provided for effecting a determination of the refractive index of the S+PDAO, such that the controlling of the at least one operating parameter of the deasphalter, by the controller, is based on at least the refractive index of the S+PDAO phase that is determined by the densitometer.

7. The de-asphalting system of claim 6, wherein the refractive index determining device includes a refractometer, wherein the refractometer is provided for effecting a determination of the refractive index of the S+PDAO, such that the controlling of the at least one operating parameter of the deasphalter, by the controller, is based on at least the refractive index of the S+PDAO phase that is determined by the refractometer.

8. The de-asphalting system of claim 2 wherein the refractive index of the S+PDAO is calculated as a function of the portion of the precipitated asphaltenes, the refractive index of the feed composition, the refractive index of the solvent, the UOP-K characterization factor of the solvent, and the operating temperature according to the following formulas:

{RI}_{S + PDAO @ T ° C .} = {RI}_{S + {PDAO}_{0} @ T ° C .} + slope \times \frac{M_{Pitch}}{M_{Feed}^{C 5 - asphaltenes}};

{RI}_{S + {PDAO}_{0} @ T ° C .} = A_{0} + (A_{1} \times {RI}_{Feed @ T ° C .} + A_{2} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{3}}; and

slope = A_{4} + (A_{5} \times {RI}_{Feed @ T ° C .} + A_{6} \times {RI}_{Solvent @ T ° C .}) \times UOP - K_{Solvent}^{A_{7}} .

9. A method for solvent de-asphalting comprising:

providing a feed, including asphaltenes, at a feed flow rate;

providing a solvent at a solvent flow rate;

contacting the solvent and the feed at an operating temperature to effect precipitation of at least a portion of the asphaltenes to obtain a S+PDAO and an asphaltene-rich material fraction, wherein the asphaltene-rich material fraction includes the precipitated asphaltenes; and

controlling one operating parameter based on at least a refractive index of the S+PDAO, the operating parameter selected from: the operating temperature; the composition of the feed; the composition of the solvent; a ratio of the precipitated asphaltenes to the mass of asphaltenes within the feed; and a ratio of the feed flow rate to the solvent flow rate.

10. A deasphalted oil obtained by a method comprising the steps of:

providing a feed, including asphaltenes, at a feed flow rate;

providing a solvent at a solvent flow rate;

11. A method for solvent de-asphalting comprising:

defining at least the following operating parameters: a composition of a feed including asphaltenes; a target ratio of a mass of removed asphaltenes to the mass of asphaltenes within the feed; an operating temperature for contacting the feed and a solvent; and a ratio of a feed flow rate of the feed to a solvent flow rate of the solvent;

determining an RI of the solvent based at least on calculating the RI of a S+PDAO formed by contacting the feed with the solvent,

selecting a solvent based at least on the determined solvent RI, and

contacting the selected solvent with the feed at the operating parameters to effect de-asphalting.

12. A method for starting up a solvent deasphalting process comprising:

pre-determining four operating parameters, the operating parameters are selected from: an operating temperature; a composition of a feed; a composition of a solvent; a target ratio of a mass of precipitated asphaltenes to a mass of asphaltenes initially within the feed; and a ratio of a feed flow rate to a solvent flow rate

determining the non-predetermined operating parameter based on at least an expected RI of an S+PDAO stream generated by the process; and

starting up the process using the pre-determined operating parameters and the determined operating parameter.