ASTM D7157-2009 1875 Standard Test Method for Determination of Intrinsic Stability of Asphaltene-Containing Residues Heavy Fuel Oils and Crude Oils (n-Heptane Phase Separation Opti.pdf
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1、Designation: D 7157 09An American National StandardStandard Test Method forDetermination of Intrinsic Stability of Asphaltene-ContainingResidues, Heavy Fuel Oils, and Crude Oils (n-Heptane PhaseSeparation; Optical Detection)1This standard is issued under the fixed designation D 7157; the number imme
2、diately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 Thi
3、s test method covers a procedure for quantifying theintrinsic stability of the asphaltenes in an oil by an automaticinstrument using an optical device.1.2 This test method is applicable to residual products fromthermal and hydrocracking processes, to products typical ofSpecifications D 396 Grades No
4、. 5L, 5H, and 6, and D 2880Grades No. 3-GT and 4-GT, and to crude oils, providing theseproducts contain 0.5 mass% or greater concentration of as-phaltenes (see Test Method D 6560).1.3 This test method quantifies asphaltene stability in termsof state of peptization of the asphaltenes (S-value), intri
5、nsicstability of the oily medium (So) and the solvency requirementsof the peptized asphaltenes (Sa).1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if
6、any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use2. Referenced Documents2.1 ASTM Standards:2D 396 Specification for Fuel OilsD 2880 Specifica
7、tion for Gas Turbine Fuel OilsD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 4870 Test Method for Determination of Total Sedime
8、nt inResidual FuelsD 6560 Test Method for Determination of Asphaltenes(Heptane Insolubles) in Crude Petroleum and PetroleumProductsD 6792 Practice for Quality System in Petroleum Productsand Lubricants Testing Laboratories3. Terminology3.1 Definitions:3.1.1 For definitions of some terms used in this
9、 test method,refer to Terminology D 4175.3.1.2 asphaltene, nin petroleum technology, a moleculeof high molecular mass, high carbon/hydrogen ratio, andcontaining hetero-atoms.3.1.2.1 DiscussionAsphaltenes are found largely in crudeoils and in heavy fuel oils containing residual fractions. Theyare ins
10、oluble in alkanes such as n-heptane and cetane, butsoluble in aromatic solvents such as benzene, toluene, and1-methylnaphthalene.3.1.3 compatibility, nof crude oils or of heavy fuel oils,the ability of two or more crude oils or fuel oils to blendtogether within certain concentration ranges without e
11、videnceof separation, such as the formation of multiple phases.3.1.3.1 DiscussionIncompatible heavy fuel oils or crudeoils, when mixed or blended, result in the flocculation orprecipitation of asphaltenes. Some oils may be compatiblewithin certain concentration ranges in specific mixtures, butincomp
12、atible outside those ranges.3.1.4 flocculation, nof asphaltenes from crude oils orheavy fuel oils, the aggregation of colloidally dispersed as-phaltenes into visible larger masses which may or may notsettle.3.1.5 peptization, nof asphaltenes in crude oils or heavyoils, the dispersion of asphaltenes
13、to produce a colloidaldispersion.3.1.6 stability reserve, nin petroleum technology, theproperty of an oil to maintain asphaltenes in a peptized stateand prevent flocculation of asphaltenes.1This test method is under the jurisdiction of Committee D02 on PetroleumProducts and Lubricants and is the dir
14、ect responsibility of Subcommittee D02.14 onStability and Cleanliness of Liquid Fuels.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 2005. Last previous edition approved in 2005 as D 715705.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
15、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
16、t Conshohocken, PA 19428-2959, United States.3.1.6.1 DiscussionAn oil with a low stability reserve islikely to undergo flocculation of asphaltenes when stressed (forexample, extended heated storage) or blended with a range ofother oils. Two oils each with a high stability reserve are likelyto mainta
17、in asphaltenes in a peptized state and not lead toflocculation when blended together.3.2 Definitions of Terms Specific to This Standard:3.2.1 intrinsic stability (S-value), nof refinery residualstreams, residual fuel oils and crude oils, an indication of thestability or available solvency power of a
18、n oil with respect toprecipitation of asphaltenes.3.2.1.1 DiscussionSince the equation defining S-value isS =(1+Xmin), where Xminis the minimum volume (in mL) ofparaffinic solvent, n-heptane, to be added to1gofoiltoresultin flocculation of asphaltenes, the smallest S-value is 1, whichmeans the oil i
19、s unstable and can precipitate asphalteneswithout addition of any paraffinic solvent. A higher S-valueindicates that an oil is more stable with respect to flocculationof asphaltenes. S-value by this test method relates specificallyto toluene and n-heptane as the aromatic and paraffinic sol-vents, re
20、spectively.3.2.2 inversion point, npoint in the n-heptane titrationcurve, where the onset of asphaltene flocculation leads toinversion of the light intensity.3.2.2.1 DiscussionAt the first stage of the addition ofn-heptane to a dilution of specimen and toluene, light intensityincreases through dilut
21、ion. When asphaltenes start to floccu-late, there will be a point where the increase in light intensitythrough dilution matches the light intensity decrease (inver-sion) as a result of coagulated asphaltenes obstructing the lightbeam.3.2.3 Sa, nthe S-value of an asphaltene, which is thepeptizability
22、 or ability of an asphaltene to remain in a colloidaldispersion.3.2.3.1 DiscussionSa can also be described as one minusthe ratio of So to S. Sa is linked to the length and number ofaromatic chains within the asphaltenes.3.2.4 So, nthe S-value of an oil.3.2.4.1 DiscussionSo can also be described as t
23、he aro-matic equivalent of the oil expressed as the ratio of thearomatic solvent to the aromatic plus paraffinic solvent mixturehaving the same peptizing power as the oil.3.2.5 solvent aromaticity, nof a binary mixture of aparaffnic and an aromatic solvent, the solvency power of thebinary mixture.3.
24、2.5.1 DiscussionFor the purpose of this test method,solvent aromaticity is defined as a ratio by volume of thearomatic solvent (toluene) to the paraffinic solvent (n-heptane).3.3 Symbols:FR = flocculation ratioFRmax= maximum flocculation ratioS = the intrinsic stability of an oilSa = the peptizabili
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