ASTM D7061-2006 Standard Test Method for Measuring n-Heptane Induced Phase Separation of Asphaltene-Containing Heavy Fuel Oils as Separability Number by an Optical Scanning Device《.pdf

1、Designation: D 7061 06An American National StandardStandard Test Method forMeasuring n-Heptane Induced Phase Separation ofAsphaltene-Containing Heavy Fuel Oils as SeparabilityNumber by an Optical Scanning Device1This standard is issued under the fixed designation D 7061; the number immediately follo

2、wing 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test metho

3、d covers the quantitative measurement,either in the laboratory or in the field, of how easily asphaltene-containing heavy fuel oils diluted in toluene phase separateupon addition of heptane. This is measured as a separabilitynumber (%) by the use of an optical scanning device.1.2 The test method is

4、limited to asphaltene-containingheavy fuel oils. ASTM specification fuels that generally fallwithin 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. Refin-ery fractions from which such

5、 blended fuels are made also fallwithin the scope of this 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.

6、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 use.2. Referenced Documents2.1 ASTM Standards:2D 396 Specification for Fuel OilsD 975 Specification for Diesel Fuel OilsD 288

7、0 Specification for Gas Turbine Fuel OilsD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products3. Terminology3.1 Definitions:3.1.1 asphaltene, nin petroleum technology, a moleculeof high molecular mass, high car

8、bon/hydrogen ratio, andcontaining heteroatoms.3.1.1.1 DiscussionAsphaltenes are found largely in crudeoils and in heavy fuel oils containing residual fractions. Theyare insoluble in alkanes, such as n-heptane and cetane, butsoluble in aromatic solvents, such as benzene, toluene, and1-methylnaphthale

9、ne.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 fuel oils or crudeoils, wh

10、en 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, the aggregation of colloida

11、lly 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 of an oil to maintain asp

12、haltenes 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 each with a high stability

13、reserve are likely1This 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 May 1, 2006. Published June 2006. Originallyapproved in

14、 2004. Last previous edition approved in 2005 as D 706105a.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.1*

15、A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to maintain asphaltenes in a peptized state and not lead toflocculation when blended together.3.1.6 transmittance, nof li

16、ght, 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 Heavy Fuel v. 1.03, nthe name of a proprietarycomputer program designed to allow automatic control of testand calcula

17、tions of the results in Test Method D 7061.3.2.2 separability number, nin petroleum technology, thestandard deviation of the average transmittance, determined inthis test method, expressed as a percentage figure.3.2.2.1 DiscussionThe separability number estimates thestability reserve of the oil, whe

18、re 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 Turbisoft3, nthe name of a proprietary computerspreadsheet program, designed to allow automatic calculationof the results in Test Method D 7061

19、.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 increase in transmittance in the sample from thebottom of a test tube to the top (o

20、r a portion thereof) over time.The standard deviation of the average transmittance from anumber of scans gives a separability number (%).4.2 The oil is first diluted with toluene in ratios that dependon the oil type (Annex A1). Mix 2 mL of the oil/toluenesolution with 23 mL of heptane. Transfer 7 mL

21、 of theoil/toluene/heptane mixture into a glass vial that is inserted intoan optical scanning device.4.3 The change in light transmittance through the glass vialcontaining the oil/toluene/heptane mixture is recorded byscanning the vial vertically with the optical scanning device.One scan is run ever

22、y 60 s for 15 min. An average of thetransmittance is calculated from 1125 readings at 0.04-mmintervals along the glass vial, starting 10 mm above the bottomof the vial and continuing up to 55 mm for each scan. Theseparability number from 16 scans is calculated and reported.5. Significance and Use5.1

23、 This procedure describes a rapid and sensitive 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 numb

24、er isbetween 0 to 5, the oil can be considered 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 th

25、e oil is not exposed toany worse conditions, 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 ofo

26、ils, for which this test method is applicable, to estimate thestability reserves of their oils. Hence, this test method can beused 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,

27、andafter storage.5.3 This test method is not intended for predicting whetheroils are compatible before mixing, but can be used fordetermining the separability number of already blended oils.However, oils that show a low separability number are morelikely to be compatible with other oils than are oil

28、s with highseparability numbers.6. Apparatus6.1 PC-based Computer, into which the software3thatcontrols the apparatus can be loaded. Data is acquired andaccumulated on the hard disk in the computer.6.2 Optical Scanning DeviceThe apparatus3consists of areading head, composed of a pulsed infrared ligh

29、t source thatuses a wavelength of 850 nm. A detector is situated oppositefrom the light source and reads the transmittance through theglass vial containing the specimen. During a scan, the readinghead moves up and down along the glass vial and scans thewhole vial going up. The transmittance is autom

30、atically mea-sured every 0.04 mm. During one measurement, the timeinterval between each scan shall be 60 s and 16 scans shall berun. The measuring principle is schematically shown in Fig. 1.3The sole source of supply of the optical scanning device (Turbiscan MA2000or Turbiscan Heavy Fuel), and corre

31、sponding software (Turbisoft or Heavy Fuel v.1.0), known to the committee at this time is available from Formulaction, 10Impasse Borde Basse, 31240 lUnion, France. This device has been foundsatisfactory for the purpose of this test method. If you are aware of alternativesuppliers, please provide thi

32、s information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.FIG. 1 Schematic Representation of a Typical MeasurementUsing an Optical Scanning DeviceD7061062The measured transmittance along

33、the glass vial is reportedevery 0.04 mm and is automatically stored on the hard disk inthe computer and can be further processed as described inSection 10 and Annex A2 and Annex A3.6.3 Cylindrical Clear Glass Vial with Screw Cap, 15 mL, 16mm outside diameter, 12 mm inner diameter, and 140 mm high,sh

34、all be used as a sample container.6.4 Pipette, Graduated or Automatic, 5 and 10 mL.6.5 Graduated Cylinder,25mL.6.6 Clear Glass Bottle with Cap, 250 mL.6.7 Clear Glass Bottle with Cap,50mL.6.8 Magnetic Bar, TFE-fluorocarbon-coated.6.9 Magnetic Stirrer.6.10 Balance, precision 60.01 g.7. Reagents and M

35、aterials7.1 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 cause flash fire.)8. Sampling and Test Specimens8.1 The oil s

36、ample drawn for the purpose of this test methodshall be representative of the lot of oil. Obtain the sample inaccordance with the procedures of Practice D 4057 or D 4177,if possible.8.2 When working with the oil sample in the laboratory, theoil shall be stirred either manually or mechanically until

37、themixture is homogenous and representative for the wholesample before withdrawing oil 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 drum is heated, by an electrical heating belt or steam shed)to obtain a lo

38、wer 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.9. Procedure9.1 With the aim to increase and achieve a comparabletransmittance for all types of oils, weig

39、h in 15 g of the oilsample on a balance and dilute with toluene, in a weight ratioin accordance with Annex A1, in a bottle with cap (6.6), andshake the bottle well. Add a magnetic bar to the oil-toluenesolution. Put the bottle on a magnetic stirrer and stir themixture for a minimum of 1 h but not mo

40、re than 3 h.9.2 Prepare the instrument for measuring by turning it onand make preparations so that one scan can be run automati-cally every 60 s for 15 min. For more detailed instructions, seeAnnex A2 and Annex A3.9.3 Using a graduated cylinder, transfer 23 mL of n-heptaneinto a glass bottle (6.7).

41、Use a pipette to add 2 mL of theoil/toluene mixture prepared in 9.1 to the heptane and shake themixture briskly for 6 s.9.4 Use a pipette to transfer 7 mL of the oil-toluene-heptanemixture immediately into the cylindrical clear glass vial andscrew the cap on (6.3).9.5 Immediately place the cylindric

42、al glass vial, with cap, inthe instrument at ambient temperature (20 to 25C) and start tomeasure at once.NOTE 1The transmittance through the cylindrical glass vial is nowrecorded every 60 s for 15 min and stored by the software on the hard diskof the computer.9.6 When the measurement is finished, re

43、move the glassvial from the optical scanning device and clean the glass vialwith toluene in a fume hood.10. Calculation and Interpretation of Results10.1 Calculation of Results:10.1.1 The following calculations may be completed eithermanually, by using a spreadsheet program (described in AnnexA2) or

44、 automatically, using the software Heavy Fuel v. 1.0(described in Annex A3).10.1.2 Analyze the transmittance between 10 to 55 mm (10mm from the bottom of the glass vial), that is, calculate theaverage transmittance (Xi) recorded in this region for eachminute.10.1.3 Calculate the total average transm

45、ittance (XT) of eachof the 16 scans.10.1.4 Calculate the separability number using the equationfor standard deviation:Separability number 5(i51nXi2 XT!2n 2 1(1)where:Xi= average transmittance for each 60 s,XT=average of XiXT5 X11 X2. 1 X16 /16,! andn = the set of replicate measurements (16 in the me

46、thod).10.2 Interpretation of Results:10.2.1 The separability number is a rate-related factor thatgives a measure of how easily an oil phase separates uponaddition of heptane. Phase separation is due to asphalteneflocculation and sedimentation. As asphaltenes fall out ofsolution, the transmittance th

47、rough the sample increases. Therewill be a rapid change in transmittance if this process is quick,resulting in a 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

48、 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 thedeviation in percent transmittance to the nearest 0.1 %.12. Precision and Bias12.1 PrecisionThe re

49、peatability standard deviation ob-tained by the same operator with the same apparatus underconstant operating conditions is presented below:D7061063Mean of Separability Number(%)Standard Deviation(%)95 % Confidence Interval(%)0.3 0.02 0.016.9 0.6 0.417.0 0.4 0.312.1.1 The data displayed above were obtained for threefuel oils (Grade No. 6) and ten measurements were made foreach oil. The toluene dilution ratio was 1:9.12.2 ReproducibilityAround robin test is being developedand the reproducibility of this test method will be determinedand available within five ye