Fuel oil stability

Patent metadata

Field	Value
Publication number	US-10794891-B2
Application number	US-201715824453-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Dec 1, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A method for predicting the critical solvent power of a visbroken residue stream of interest, CSPVisRes(OI) comprises predicting CSPVisRes(OI) from the critical percentage titrant of an atmospheric residue stream, CPTAR, the atmospheric residue stream being derived from the same crude oil as the visbroken residue stream of interest. A method for predicting the solvent power of a visbroken residue stream of interest, SPVisRes(OI), comprises predicting SPVisRes(OI) from the critical solvent power of the visbroken residue stream, CSPVisRes, and the critical percentage titrant of the visbroken residue stream, CPTVisRes. CPTVisRes is derived from the critical percentage cetane of the visbroken residue stream, CPCVisRes, which, in turn, is calculated from the P-value of the visbroken residue stream. The methods may be used to predict the stability of a fuel oil containing the visbroken residue.

First claim

The invention claimed is:

1. A method for preparing a visbroken residue stream of interest in a refinery process, the precipitation of asphaltenes prevented from the visbroken residue stream of interest, said method comprising:
comparing solvent power of the visbroken residue stream of interest, SP VisRes(OI) , with critical solvent power of the visbroken residue stream of interest, CSP VisRes(OI) ,
categorizing the visbroken residue stream of interest as unstable if SP VisRes(OI) is not greater than CSP VisRes(OI) , and
if SP VisRes(OI) is not greater than CSP VisRes(OI) , adjusting the refinery process to provide the visbroken residue stream of interest with a value of SP VisRes(OI) that is greater than CSP VisRes(OI) ,

wherein
CSP VisRes(OI) is predicted from the critical percentage titrant for asphaltene stability in an atmospheric residue stream, CPT AR(OI) , the atmospheric residue stream of interest being derived from the same crude oil as the visbroken residue stream of interest, using a correlation obtained by a method comprising:
for each of a plurality of crude oils, determining:
CSP VisRes of a visbroken residue stream derived therefrom, and
CPT AR of an atmospheric residue stream derived therefrom, and

determining a correlation between CSP VisRes and CPT AR .

SP VisRes(OI) is predicted using the following formula:
SP VisRes(OI) =(100×CSP VisRes(OI) )/(100−CPT VisRes )

wherein:
CPT VisRes is the critical percentage titrant (vol %) for asphaltene stability in the visbroken residue stream,
wherein CPT VisRes is derived from the critical percentage cetane (vol %) for asphaltene stability in the visbroken residue stream, CPC VisRes using the following formula:
CPT VisRes =CF+CPC VisRes

wherein:
CF is a conversion factor that relates CPT VisRes to CPC VisRes ,
and wherein CPC VisRes is calculated from the P-value of the visbroken residue stream using the following formula:
CPC VisRes =([(P-value−1)*ρ VisRes ]/[((P-value−1)*ρ VisRes )+1])*100

wherein:
ρ VisRes is the density of the visbroken residue stream.

2. The method of claim 1 , wherein adjusting the refinery process comprises one or more of: modifying a feed inputted into a visbreaker unit (VSB), and modifying conditions in the VSB.

3. The method of claim 1 , wherein CPT AR (O I ) is predicted using the following formula:
CPT AR =100−(100*CPS AR )/SP AR

wherein:
CSP AR is the critical solvent power of the atmospheric residue, and
SP AR is the solvent power of the atmospheric residue.

4. The method of claim 3 , wherein CSP AR is assumed to be equal to the critical solvent power of the crude oil from which the atmospheric residue is derived.

5. The method of claim 3 , wherein SP AR is obtained by a method comprising:
titrating a precipitant against at least two samples of the atmospheric residue diluted with different amounts of solvent to determine a volume fraction of the atmospheric residue at the onset of asphaltene precipitation, V (onset fraction AR) , and a volume fraction of the solvent at the onset of asphaltene precipitation, V (onset fraction S); and
deriving SP AR from a linear correlation between SP S *V (onset fraction S) and V (onset fraction AR) based on the following formula:

SP
AR

=

(

CSP
AR

-

SP
S

*

V

(

onset
⁢

⁢
fraction
⁢

⁢
S

)

)

V

(

onset
⁢

⁢
fraction
⁢

⁢
AR

)

wherein:
CSP AR is the critical solvent power of the atmospheric residue, and
SP S is the solvent power of the solvent.

6. The method of claim 1 , wherein the method for predicting CSP VisRes(OI) comprises:
predicting CSP VisRes(OI) from the critical percentage titrant for asphaltene stability in an atmospheric residue stream, CPT AR(OI) , derived from the same crude oil as the visbroken residue stream, and the ratio of feed rate to coil outlet temperature (COT) of visbreaker unit (VSB) in which the visbroken residue of interest is produced,
wherein the method for obtaining a correlation between CPT AR and CSP VisRes comprises:
assigning each of the plurality of crude oils to a subgroup based on the ratio of the feed rate to COT of the VSB in which the visbroken residue is produced, and
determining a correlation between CPT AR and CSP VisRes for each subgroup.

7. The method of claim 1 , wherein the P-value for the visbroken residue stream is in the range of from 1.05 to 1.30.

8. The method of claim 1 , wherein CF is determined using a method which comprises measuring CPT VisRes and CPC VisRes for a plurality of visbroken residue streams; and deriving the conversion factor, CF, that relates CPT VisRes to CPC VisRes .

9. The method of claim 1 , wherein CPT VisRes is the critical percentage titrant, the titrant being selected from C 5-8 n-alkanes or C 5-8 iso alkanes.

10. A method for preparing a fuel oil in a refinery process, the precipitation of asphaltenes prevented from the fuel oil, the fuel oil containing n blend components including a visbroken residue stream of interest, said method comprising:
in a refinery process, visbreaking a residue stream to provide the visbroken residue stream of interest,
comparing solvent power of the fuel oil, SP FO , with critical solvent power of the fuel oil, CSP FO ,
categorizing the fuel oil as unstable if SP FO is not greater than CSP FO , and
if SP FO is not greater than CSP FO , adjusting the refinery process and blending the visbroken residue stream of interest with the n-1 other blend components to provide the fuel oil to produce a fuel oil for which SP FO is greater than CSP FO ,

wherein
CSP FO is predicted using the following formula:

CSP
FO

=

∑

i
=
1

Assignees

• Bp Corp North America Inc

Inventors

• Balashanmugam Soban
• Rueda-Velasquez Rosa

Classifications

• G01N33/28

  Oils {, i.e. hydrocarbon liquids} (edible oils or edible fats G01N33/03) · CPC title

• C10G2300/206

  Asphaltenes · CPC title

• G01N33/2823 Primary

  Raw oil, drilling fluid or polyphasic mixtures · CPC title

• C10G75/00

  Inhibiting corrosion or fouling in apparatus for treatment or conversion of hydrocarbon oils, in general (C10G7/10, C10G9/16 take precedence) · CPC title

• C10G2300/1077

  Vacuum residues · CPC title