1、Designation: D7827 12 (Reapproved 2017)Standard 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 indicat
2、es 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. Scope1.1 This test method covers the quantitative meas
3、urement,either in 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.
4、ASTM specification 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 t
5、his test method.1.3 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 t
6、o establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Prin
7、ciples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D396 Specification for Fuel OilsD975 Specification for Diesel Fuel OilsD2880 Specification fo
8、r Gas Turbine Fuel OilsD4057 Practice for Manual Sampling 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 O
9、ptical Scanning Device3. Terminology3.1 Definitions:3.1.1 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
10、 test method, the aromatic sol-vent is toluene and the paraffinic 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
11、of multiple phases.3.1.2.1 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, butincompatible outside those ranges.3.1.3 flocculati
12、on, nof asphaltenes from crude oils orheavy fuel oils, the 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
13、stability reserve, nin petroleum technology, theproperty 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 s
14、torage) or blended with a range ofother oils. Two oils each with a high stability reserve are likely1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.14 on Stability, Cleanliness an
15、d Compatibility of Liquid Fuels.Current edition approved Dec. 1, 2017. Published December 2017. Originallyapproved in 2012. Last previous edition approved in 2012 as D7827 12. DOI:10.1520/D7827-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
16、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acc
17、ordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1to maintain asphaltenes in a p
18、eptized 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 Definitions of Terms Specific to This Standard:3.2.1 SEPView 6.1, nthe name of
19、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, thestandard deviation of the average transmittance, determined inthis test method, expressed as a percentage figure.3.2.2
20、.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 number that the oil has a high stability reserve.3.2.3 SEPCalc, nthe name of a proprietary computerprogram modul of
21、 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 I is detected bymultiple sensors with a m-scale resolution arranged linearlyfrom top to bottom. Transmission is
22、 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 to flocculate, and the oil to phaseseparate. The rate of the phase separation is determined bymeasuring the in
23、crease 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 consecutive automatic measurements gives a sepa-rability number (%).4.2 The oil is diluted with toluene in ratios that d
24、epend 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 opticalscanning device.4.3 The change in light transmittance through the cell isrecorded by proprietary STEP-Tech
25、nology 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 of each of the 91transmission profiles at each 0.007 mm distance along theoptical cell, starting from the bot
26、tom 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 sensitive methodfor estimating the stability reserve of an oil. The stabilityreserve is estimated in terms of a se
27、parability 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 considered to have a highstability reserve and asphaltenes are not likely to flocculate. Ifthe separability number i
28、s 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 conditions, such as storing, aging, and heating. If theseparability number is above 10, the stability reserve of the oi
29、lis 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 applicable, to estimatethe stability reserves of their oils. Hence, this test method canbe used by refineries t
30、o 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 method is not intended for predicting whetheroils are compatible before mixing, but can be used fordetermining the
31、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 separability numbers.6. Apparatus6.1 Computer executing software SEPView3, from a portablestorage media or dir
32、ectly 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 Optical DeviceThe apparatus3consists of an illumi-nation system, composed of a pulsed infrared light source thatuse
33、s a wavelength of 870 nm (6 10 nm) and means to paral-lelize and expand the light to illuminate the entire specimenheight.Ahigh-resolution line detector is situated opposite fromthe light source and reads the transmittance through the verticalmidline of the optical cell (6.3) containing the specimen
34、. Thetransmittance is automatically and instantaneously recorded atevery pixel with a position resolution of 0.007 mm (STEP-Technology (trademarked)3). Time interval between each re-cording shall be 10 s. Total measurement time shall be 15 min.The measuring principle is schematically shown in Fig. 1
35、. Eachmeasured transmittance profile along the optical cell is auto-matically stored on the hard disk in the computer or at a serverand can be further processed as described in Section 10 andAnnex A2.6.3 Rectangular Transparent Disposable Optical Polyamidcells (PA-cells) with PP-stopper, 5 mL capaci
36、ty, cross-section8 mm 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 mL and 10 mL.6.5 Graduated Cylinder, 25 mL.6.6 Clear Glass Bottle with Cap, 250 mL.3The sole source of supply of the optical device (LUMiReader 41
37、3-1 (onechannel) or LUMiReader 413-3 (three channel), and corresponding software(SEPView 6), known to the committee at this time is available from LUM GmbH,Justus-von-Liebig-Str.3, 12489 Berlin, Germany.D7827 12 (2017)26.7 Clear Glass Bottle with Cap, 50 mL.6.8 Magnetic Bar, PTFE-coated.6.9 Magnetic
38、 Stirrer.6.10 Balance, precision 60.01 g.7. Reagents and Materials7.1 Purity of ReagentsReagents of technical grade (95 %purity) and higher are adequate for this test.7.2 Heptane. (WarningFlammable. Vapor harmful. Va-por may cause flash fire.)7.3 Toluene. (WarningFlammable. Vapor harmful. Vapormay c
39、ause 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 procedures of Practice D4057 orD4177, if possible.8.2 When working with the oil sample in the laboratory
40、, 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 highly viscous oils, the oilmay be heated (for example, on a heating plate, in an oven, or,if a dru
41、m 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 the sample withdrawn is repre-sentative of the whole sample.8.3.1 Heating has to be performed i
42、n closed containers.Avoid heating above 60 C 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 dilute with toluene, in a weight ratio in accordance withAnnexA1, in a bottle with cap (6.6), and sh
43、ake 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 by turning it onand make preparations so that consecutive measurements canbe run automatically
44、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 prepared in 9.1 to the heptane and shake themixture briskly for exactly 6 s.9.4 Use a pipette t
45、o 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 temperature (for example, 25 C), closethe lid. Measurements start automatically.NOTE 1The transmitt
46、ance 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-posable optical cell from the optical device, and dispose of it inan environmentally safe way
47、.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 the data may be exported to another piece ofsoftware for manual analysis.10.1.2 Analyze the t
48、ransmittance between 0 mm to 44 mm,that is, 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 measurements.10.1.4 Calculate the separability number using Eq 1.Separability number 5!i51n
49、Xi2 XT!2n 2 1(1)where in the case of 91 profiles:Xi= average transmittance for each of the transmissionprofiles,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 12 (2017)3XT= average of XiXT5 X11 X2. 1 X91! 91! andn = the number of replicated profiles (91 in the testmethod).10.2 Interpretation of Results:10.2.1 The separability number is a rate-related factor thatgives a measure of how easily asphaltenes destabiliz
