ASTM D7061-06
(Test Method)Standard Test Method for Measuring n-Heptane Induced Phase Separation of Asphaltene-Containing Heavy Fuel Oils as Separability Number by an Optical Scanning Device
Standard Test Method for Measuring n-Heptane Induced Phase Separation of Asphaltene-Containing Heavy Fuel Oils as Separability Number by an Optical Scanning Device
SIGNIFICANCE AND USE
This procedure describes a rapid and sensitive method for estimating the stability reserve of an oil. The stability reserve is estimated in terms of a separability number, where a low value of the separability number indicates that there is a stability reserve within the oil. When the separability number is between 0 to 5, the oil can be considered to have a high stability reserve and asphaltenes are not likely to flocculate. If the separability number is between 5 to 10, the stability reserve in the oil will be much lower. However, asphaltenes are, in this case, not likely to flocculate as long as the oil is not exposed to any worse conditions, such as storing, aging, and heating. If the separability number is above 10, the stability reserve of the oil is very low and asphaltenes will easily flocculate, or have already started to flocculate.
This test method can be used by refiners and users of oils, for which this test method is applicable, to estimate the stability reserves of their oils. Hence, this test method can be used by refineries to control and optimize their refinery processes. Consumers of oils can use this test method to estimate the stability reserve of their oils before, during, and after storage.
This test method is not intended for predicting whether oils are compatible before mixing, but can be used for determining the separability number of already blended oils. However, oils that show a low separability number are more likely to be compatible with other oils than are oils with high separability numbers.
FIG. 1 Schematic Representation of a Typical Measurement Using an Optical Scanning Device
SCOPE
1.1 This test method covers the quantitative measurement, either in the laboratory or in the field, of how easily asphaltene-containing heavy fuel oils diluted in toluene phase separate upon addition of heptane. This is measured as a separability number (%) by the use of an optical scanning device.
1.2 The test method is limited to asphaltene-containing heavy fuel oils. ASTM specification fuels that generally fall within the scope of this test method are Specification D 396, Grade Nos. 4, 5, and 6, Specification D 975, Grade No. 4-D, and Specification D 2880, Grade Nos. 3-GT and 4-GT. Refinery fractions from which such blended fuels are made also fall within the scope of this test method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7061 − 06
StandardTest Method for
Measuring n-Heptane Induced Phase Separation of
Asphaltene-Containing Heavy Fuel Oils as Separability
1
Number by an Optical Scanning Device
This standard is issued under the fixed designation D7061; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 3. Terminology
1.1 This test method covers the quantitative measurement, 3.1 Definitions:
eitherinthelaboratoryorinthefield,ofhoweasilyasphaltene-
3.1.1 asphaltene, n—in petroleum technology,amoleculeof
containing heavy fuel oils diluted in toluene phase separate
high molecular mass, high carbon/hydrogen ratio, and contain-
upon addition of heptane. This is measured as a separability
ing heteroatoms.
number (%) by the use of an optical scanning device.
3.1.1.1 Discussion—Asphaltenes are found largely in crude
1.2 The test method is limited to asphaltene-containing oils and in heavy fuel oils containing residual fractions. They
heavy fuel oils. ASTM specification fuels that generally fall are insoluble in alkanes, such as n-heptane and cetane, but
within the scope of this test method are Specification D396, soluble in aromatic solvents, such as benzene, toluene, and
Grade Nos. 4, 5, and 6, Specification D975, Grade No. 4-D, 1-methylnaphthalene.
andSpecificationD2880,GradeNos.3-GTand4-GT.Refinery
3.1.2 compatibility, n—of crude oils or of heavy fuel oils,
fractions from which such blended fuels are made also fall
the ability of two or more crude oils or fuel oils to blend
within the scope of this test method.
together within certain concentration ranges without evidence
1.3 The values stated in SI units are to be regarded as
of separation, such as the formation of multiple phases.
standard. No other units of measurement are included in this
3.1.2.1 Discussion—Incompatible heavy fuel oils or crude
standard.
oils, when mixed or blended, result in the flocculation or
precipitation of asphaltenes. Some oils may be compatible
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the within certain concentration ranges in specific mixtures, but
responsibility of the user of this standard to establish appro- incompatible outside those ranges.
priate safety and health practices and determine the applica-
3.1.3 flocculation, n— of asphaltenes from crude oils or
bility of regulatory limitations prior to use.
heavy fuel oils, the aggregation of colloidally dispersed as-
phaltenes into visibly larger masses that may or may not settle.
2. Referenced Documents
2
3.1.4 peptization, n— of asphaltenes in crude oils or heavy
2.1 ASTM Standards:
fuel oils, the dispersion of asphaltenes to produce a colloidal
D396 Specification for Fuel Oils
dispersion.
D975 Specification for Diesel Fuel Oils
D2880 Specification for Gas Turbine Fuel Oils
3.1.5 stability reserve, n—in petroleum technology, the
D4057 Practice for Manual Sampling of Petroleum and
property of an oil to maintain asphaltenes in a peptized state
Petroleum Products
and prevent flocculation of the asphaltenes.
D4177 Practice for Automatic Sampling of Petroleum and
3.1.5.1 Discussion—An oil with a low stability reserve is
Petroleum Products
likelytoundergoflocculationofasphalteneswhenstressed(for
example, extended heated storage) or blended with a range of
1
This test method is under the jurisdiction of ASTM Committee D02 on
other oils.Two oils each with a high stability reserve are likely
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
to maintain asphaltenes in a peptized state and not lead to
D02.14 on Stability and Cleanliness of Liquid Fuels.
flocculation when blended together.
Current edition approved May 1, 2006. Published June 2006. Originally
approved in 2004. Last previous edition approved in 2005 as D7061–05a. DOI:
3.1.6 transmittance, n—of light, the fraction of the incident
10.1520/D7061-06.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or light of a given wavelength that is not reflected or absorbed,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
but passes through a substance.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 3.2 Definitions of Terms Specific to This Standard:
*A Summary of Changes section appears at the end of this standard
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D7061 − 06
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3.2.1 Heavy Fuel v. 1.0 , n—the name of a proprieta
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