1、Designation: D7827 12Standard Test Method forMeasuring n-Heptane Induced Phase Separation ofAsphaltene from Heavy Fuel Oils as Separability Number byan Optical Device1This standard is issued under the fixed designation D7827; the number immediately following the designation indicates the year oforig
2、inal 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. Scope1.1 This test method covers the quantitative measurement,either in
3、the laboratory or in the field, of how easily asphaltene-containing heavy fuel oils diluted in toluene phase separateupon addition of heptane. The result is a separability number(%). See also Test Method D7061.1.2 The test method is limited to asphaltene-containingheavy fuel oils. ASTM specification
4、 fuels that generally fallwithin the scope of this test method are Specification D396,Grade Nos. 4, 5, and 6, Specification D975, Grade No. 4-D,and Specification D2880, Grade Nos. 3-GT and 4-GT. Refineryfractions from which such blended fuels are made also fallwithin the scope of this test method.1.
5、3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-
6、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D396 Specification for Fuel OilsD975 Specification for Diesel Fuel OilsD2880 Specification for Gas Turbine Fuel OilsD4057 Practice for Manual Sampling
7、 of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD7061 Test Method for Measuring n-Heptane Induced PhaseSeparation of Asphaltene-Containing Heavy Fuel Oils asSeparability Number by an Optical Scanning Device3. Terminology3.1 Definitions:3.1.1
8、 asphaltenes (rarely used in the singular), nin petro-leum technology, represent an oil fraction that is soluble in aspecified aromatic solvent but separates upon addition of anexcess of a specified paraffinic solvent.3.1.1.1 DiscussionIn this test method, the aromatic sol-vent is toluene and the pa
9、raffinic solvent is heptane.3.1.2 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 evidenceof separation, such as the formation of multiple phases.3.1.2.1 DiscussionIncompatible heavy f
10、uel 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, butincompatible outside those ranges.3.1.3 flocculation, nof asphaltenes from crude oils orheavy fuel oils, th
11、e aggregation of colloidally dispersed as-phaltenes into visibly larger masses that may or may not settle.3.1.4 peptization, nof asphaltenes in crude oils or heavyfuel oils, the dispersion of asphaltenes to produce a colloidaldispersion.3.1.5 stability reserve, nin petroleum technology, theproperty
12、of an oil to maintain asphaltenes in a peptized stateand prevent flocculation of the asphaltenes.3.1.5.1 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 ea
13、ch with a high stability reserve are likelyto maintain asphaltenes in a peptized state and not lead toflocculation when blended together.3.1.6 transmittance, nof light, the fraction of the incidentlight of a given wavelength that is not reflected or absorbed,but passes through a substance.3.2 Defini
14、tions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Nov. 1, 2012. Published March 20
15、13. DOI: 10.1520/D7827-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 B
16、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1 SEPView 6.1, nthe name of a proprietary computerprogram designed to allow automatic control of test andcalculations of the results in Test Method D7827.3.2.2 separability number, nin petroleum technology, thestandar
17、d deviation of the average transmittance, determined inthis test method, expressed as a percentage figure.3.2.2.1 DiscussionThe separability number estimates thestability reserve of the oil, where a high separability numberindicates that the oil has a low stability reserve and a lowseparability numb
18、er that the oil has a high stability reserve.3.2.3 SEPCalc, nthe name of a proprietary computerprogram modul of SEPView, designed to allow automaticcalculation of the results in Test Method D7827.3.2.4 STEP-Technology, nparallel light (I0) illuminates theentire sample cell and the transmitted light
19、I is detected bymultiple sensors with a m-scale resolution arranged linearlyfrom top to bottom. Transmission is recorded time- andspace-resolved and may be converted into extinction by lg I/I0.4. Summary of Test Method4.1 Dilution of oil with toluene followed by addition ofheptane causes asphaltenes
20、 to flocculate, and the oil to phaseseparate. The rate of the phase separation is determined bymeasuring the increase in transmittance in the sample from thebottom of a test tube to the top (or a portion thereof) over time.The standard deviation of the average transmittance from anumber of consecuti
21、ve automatic measurements gives a sepa-rability number (%).4.2 The oil is diluted with toluene in ratios that depend onthe oil type. Mix 2 mL of the oil/toluene solution with 23 mLof heptane. Transfer 3.5 mL of the oil/toluene/heptane mixtureinto a disposable optical cell that is inserted into an op
22、ticalscanning device.4.3 The change in light transmittance through the cell isrecorded by proprietary STEP-Technology instantaneouslyover the entire sample height without scanning. Measurementsare taken periodically every 10 s for 15 min.An average of thetransmittance is calculated from each reading
23、 of each of the 91transmission profiles at each 0.007 mm distance along theoptical cell, starting from the bottom of the cell and continuingup to 44 mm. The separability number from multiple measure-ments is calculated and reported.5. Significance and Use5.1 This procedure describes a rapid and sens
24、itive methodfor estimating the stability reserve of an oil. The stabilityreserve is estimated in terms of a separability number, where alow value of the separability number indicates that there is astability reserve within the oil. When the separability number isbetween 0 to 5, the oil can be consid
25、ered to have a highstability reserve and asphaltenes are not likely to flocculate. Ifthe separability number is between 5 to 10, the stability reservein the oil will be much lower. However, asphaltenes are, in thiscase, not likely to flocculate as long as the oil is not exposed toany worse condition
26、s, such as storing, aging, and heating. If theseparability number is above 10, the stability reserve of the oilis very low and asphaltenes will easily flocculate, or havealready started to flocculate.5.2 This test method can be used by refiners and users ofheavy oils, for which this test method is a
27、pplicable, to estimatethe stability reserves of their oils. Hence, this test method canbe used by refineries to control and optimize their refineryprocesses. Consumers of oils can use this test method toestimate the stability reserve of their oils before, during, andafter storage.5.3 This test metho
28、d is not intended for predicting whetheroils are compatible before mixing, but can be used fordetermining the separability number of already blended oils.However, experience shows that oils exhibiting a low separa-bility number are more likely to be compatible with other oilsthan are oils with high
29、separability numbers.6. Apparatus6.1 Computer executing software SEPView3, from a portablestorage media or directly from the computer. SEPView controlsthe apparatus, acquires the data and accumulates it in adatabase on the portable storage media, the hard disk in thecomputer or at a server.6.2 Optic
30、al DeviceThe apparatus3consists of an illumi-nation system, composed of a pulsed infrared light source thatuses a wavelength of 870 nm (6 10 nm) and means toparallelize and expand the light to illuminate the entirespecimen height. A high-resolution line detector is situatedopposite from the light so
31、urce and reads the transmittancethrough the vertical midline of the optical cell (6.3) containingthe specimen. The transmittance is automatically and instanta-neously recorded at every pixel with a position resolution of0.007 mm (STEP-Technology (trademarked)3). Time intervalbetween each recording s
32、hall be 10 s. Total measurement timeshall be 15 min. The measuring principle is schematicallyshown in Fig. 1. Each measured transmittance profile along theoptical cell is automatically stored on the hard disk in thecomputer or at a server and can be further processed asdescribed in Section 10 and An
33、nex A2.6.3 Rectangular Transparent Disposable Optical Polyamidcells (PA-cells) with PP-stopper, 5 mLcapacity, cross-section 8mm 10 mm (optical path), wall thickness 1 mm and 80 mmhigh, shall be used as a sample container.6.4 Pipette, Graduated or Automatic, 5 and 10 mL.6.5 Graduated Cylinder, 25 mL.
34、6.6 Clear Glass Bottle with Cap, 250 mL.6.7 Clear Glass Bottle with Cap, 50 mL.6.8 Magnetic Bar, PTFE-coated.6.9 Magnetic Stirrer.6.10 Balance, precision 60.01 g.3The sole source of supply of the optical device (LUMiReader 413-1 (onechannel) or LUMiReader 413-3 (three channel), and corresponding sof
35、tware(SEPView 6), known to the committee at this time is available from LUM GmbH,Justus-von-Liebig-Str.3, 12489 Berlin, Germany.D7827 1227. Reagents and Materials7.1 Purity of ReagentsReagents of technical grade (95 %purity) and higher are adequate for this test.7.2 Heptane. (WarningFlammable. Vapor
36、 harmful. Va-por may cause flash fire.)7.3 Toluene. (WarningFlammable. Vapor harmful. Vapormay cause flash fire.)8. Sampling and Test Specimens8.1 The oil sample collected for the purpose of this testmethod shall be representative of the batch of oil. Obtain thesample in accordance with the procedur
37、es of Practice D4057 orD4177, if possible.8.2 When working with the oil sample in the laboratory, theoil shall be stirred either manually or mechanically until themixture is homogenous and representative for the wholesample before withdrawing an aliquot for testing.8.3 When working with solid or hig
38、hly viscous oils, the oilmay be heated (for example, on a heating plate, in an oven, or,if a drum is heated, by an electrical heating belt or steam shed)to obtain a lower viscosity prior to weighing and mixing. It isthen important that the whole sample is fluid to ensure ahomogenous mixture and that
39、 the sample withdrawn is repre-sentative of the whole sample.8.3.1 Heating has to be performed in closed containers.Avoid heating above 60C and more than 60 min.9. Procedure9.1 With the aim to increase and achieve a comparabletransmittance for all types of oils, weigh 15 g of the oil sampleand dilut
40、e with toluene, in a weight ratio in accordance withAnnexA1, in a bottle with cap (6.6), and shake the bottle well.Add a magnetic bar to the oil-toluene solution. Put the bottle ona magnetic stirrer and stir the mixture for a minimum of1hbutnot more than 3 h.9.2 Prepare the instrument for measuring
41、by turning it onand make preparations so that consecutive measurements canbe run automatically every 10 s for 15 min. For more detailedinstructions, see Annex A2.9.3 Using a graduated cylinder, transfer 23 mL of n-heptaneinto a glass bottle (6.7). Use a pipette to add 2 mL of theoil/toluene mixture
42、prepared in 9.1 to the heptane and shake themixture briskly for exactly 6 s.9.4 Use a pipette to transfer 3.5 mL of the oil-toluene-heptane mixture immediately into the optical cell and closewith the stopper (6.3).9.5 Immediately place the cell, with stopper, in the instru-ment (6.2) at ambient temp
43、erature (for example, 25C), closethe lid. Measurements start automatically.NOTE 1The transmittance through the rectangular optical cell is nowrecorded every 10 s for 15 min and stored by the software on the hard diskof the computer or the server.9.6 When the measurements are finished, remove the dis
44、-posable optical cell from the optical device, and dispose of it inan environmentally safe way.10. Calculation and Interpretation of Results10.1 Calculation of Results:10.1.1 The following calculations may be run automatically,using the modul SEPCalc of the software SEPView (describedin Annex A2) or
45、 the data may be exported to another piece ofsoftware for manual analysis.10.1.2 Analyze the transmittance between 0 to 44 mm, thatis, calculate the average transmittance (Xi) recorded in thisregion for each transmission profile.10.1.3 Calculate the total average transmittance (XT) of eachof the 91
46、measurements.10.1.4 Calculate the separability number using Eq 1.Separability number 5!i51n(Xi2 XT)2n 2 1(1)where in the case of 91 profiles:Xi= average transmittance for each of the transmissionprofiles,XT= average of XiXT5X11X2.1X91!91! andn = the number of replicated profiles (91 in the testmetho
47、d).10.2 Interpretation of Results:NOTE 1First measured profile after1sinred. Last profile after 15 min in green.FIG. 1 Representation of a Typical Measurement Scheme Using an Optical Device Based on STEP-Technology.D7827 12310.2.1 The separability number is a rate-related factor thatgives a measure
48、of how easily asphaltenes destabilize uponaddition of heptane. Phase separation is due to asphalteneflocculation and sedimentation. As asphaltenes fall out ofsolution, the transmittance through the sample increases. Therewill be a rapid change in transmittance if this process is quick,resulting in a
49、 high separability number. A high number showsthat the stability reserve of the oil is poor, while a low numbershows that there is a stability reserve in the oil. The separabilitynumber is presented in percent transmittance.11. Report11.1 Report the following information:11.1.1 The toluene dilution ratio (in accordance with AnnexA1).11.1.2 The separability number of the oil sample as thechange in percent transmittance to the nearest 0.1 %.12. Precision and Bias12.1 Interim PrecisionThe repeatability standard devia-tion obtained by the same operator wit
