1、Designation: D 7060 05An American National StandardStandard Test Method forDetermination of the Maximum Flocculation Ratio andPeptizing Power in Residual and Heavy Fuel Oils (OpticalDetection Method)1This standard is issued under the fixed designation D 7060; the number immediately following the des
2、ignation 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 method covers a p
3、rocedure for quantifying themaximum flocculation ratio of the asphaltenes in the oil and thepeptizing power of the oil medium, by an automatic instrumentusing an optical device.1.2 This test method is applicable to atmospheric or vacuumdistillation residues, thermally cracked residue, intermediatean
4、d finished residual fuel oils, containing at least 1 mass %asphaltenes. This test method has not been developed forasphalts.NOTE 1An optical probe detects the formation of flocculated asphalt-enes. The start of flocculation is interpreted when a significant andsustained increase in rate-of-change of
5、 signal, as measured by the opticalprobe, ensures flocculation is in progress. The start of flocculation can bedetected unambiguously when the sample contains at least 1 % massasphaltenes as measured by Test Method D 6560.NOTE 2This test method is applicable to products typical of Specifi-cation D 3
6、96Grades 5L, 5H, and 6, and Specification D 2880Grades3-GT and 4-GT.1.3 This test method was evaluated in a within-laboratorystudy in the range of 16 to 57 for the maximum flocculationratio and in the ranges of 27 to 96 for peptizing power.1.4 This standard does not purport to address all of thesafe
7、ty concerns, if 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 use.2. Referenced Documents2.1 ASTM Standards:2D 396 Specification for Fuel Oil
8、sD 2880 Specification for Gas Turbine Fuel OilsD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 4870 Test Method for Determination of Total Sediment inResidual FuelsD 6560 Test Method for Determination of
9、 Asphaltenes(Heptane Insolubles) in Crude Petroleum and PetroleumProductsD 6792 Guide for Quality System in Petroleum Productsand Lubricants Testing Laboratories3. Terminology3.1 Definitions:3.1.1 asphaltene, nin petroleum technology, a moleculeof high molecular mass, high carbon/hydrogen ratio, and
10、containing 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-methylnaphthalene.3.1.2 compatibility, n
11、of 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, when mixed or blended, resu
12、lt 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 colloidally dispersed as-phaltene
13、s into visibly larger masses which may or may notsettle.3.1.4 peptization, nof asphaltenes in crude oils or heavyfuel oils, the dispersion of asphaltenes to produce a colloidaldispersion.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the
14、direct responsibility of SubcommitteeD02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 2004. Last previous edition approved in 2004 as D 706004.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
15、ntact 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, We
16、st Conshohocken, PA 19428-2959, United States.3.1.5 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 asph
17、altenes when stressed (forexample, extended heated storage) or blended with a range ofother oils. Two oils each with a high stability reserve are likelyto maintain asphaltenes in a peptized state and not lead toflocculation when blended together.3.2 Definitions of Terms Specific to This Standard:3.2
18、.1 critical cetane dilution, nnumber of millilitres ofcetane with which1gofundiluted sample can be diluted untilit just does not flocculate the asphaltenes.3.2.2 critical dilution, nnumber of millilitres of1-methylnaphthalene and cetane with which1gofundilutedsample can be diluted until it just does
19、 not flocculate theasphaltenes.3.2.2.1 DiscussionThe number of millilitres of1-methylnaphthalene and cetane is variable and depends on theratio of sample to 1-methylnaphthalene at the starting point andthe sample type.3.2.3 flocculation ratio, npercentage by volume of1-methylnaphtalene in a mixture
20、of 1-methylnaphthalene andcetane.3.2.4 flocculation ratio at critical dilution, npercentageby volume of 1-methylnaphthalene in a mixture of1-methylnaphthalene and cetane at the inflection point.3.2.5 inflection point, nlast step during the titration withcetane, where flocculation of asphaltenes is n
21、ot detected by theoptical probe as a significant and sustained increase in rate-of-change of signal.3.2.6 maximum flocculation ratio, nof asphaltenes, mini-mum required solvency power, expressed as percentage byvolume of 1-methylnaphthalene in a mixture of1-methylnaphthalene and cetane, to keep the
22、asphaltenes in acolloidal solution.3.2.6.1 DiscussionMaximum flocculation ratio is the floc-culation ratio at extrapolated infinite dilution of the sample.3.2.7 oil medium, nthat portion of a sample of heavy fueloil or crude oil that surrounds and colloidally disperses theasphaltenes.3.2.7.1 Discuss
23、ionFor purposes of this test method, an oilsample is considered to be composed of an oil medium(sometimes called an oil matrix or maltenes) and asphaltenes.3.2.8 peptizing power, navailable solvency power, ex-pressed as percentage by volume of 1-methylnaphthalene in amixture of 1-methylnaphthalene a
24、nd cetane, to keep asphalt-enes in a colloidal solution.3.2.9 reciprocal dilution, ndilution ratio of sample insolvent mixture of 1-methylnaphthalene and cetane.3.3 Symbols:FRmax= maximum flocculation ratioFRx= flocculation ratio at critical dilutionPo = peptizing powerXmin = critical cetane dilutio
25、nXc = critical dilution4. Summary of Test Method4.1 Six portions of the sample are diluted in various ratioswith 1-methylnaphthalene. Each solution is inserted into theautomatic apparatus, and titrated with cetane until flocculationof asphaltenes is detected by the optical probe. The first twosoluti
26、ons are titrated with cetane in coarse determinations inwhich the flocculation ratio is decreased in 5 % steps. Thecoarse determinations help to establish suitable starting valuesfor the fine determinations, in which the flocculation ratio isdecreased in 1 % steps. The four flocculation ratios at cr
27、iticaldilution, measured during the fine determinations, are used tocalculate the maximum flocculation ratio of the samplesasphaltenes and the peptizing power of the samples oilmedium.5. Significance and Use5.1 Asphaltenes are naturally occurring materials in crudepetroleum and petroleum products co
28、ntaining residual mate-rial. The asphaltenes are usually present in colloidal suspen-sions, but they may agglomerate and flocculate if the suspen-sion of asphaltene molecules is disturbed through excess stressor incompatibility. This test method provides compatibilityparameters, which can be used to
29、 assess stability reserve andcompatibility.5.2 A blend is considered stable when the blends peptizingpower is higher than the blends maximum flocculation ratio;3,4both of them can be calculated using empirical blend rules.Refineries and terminal owners can prevent the flocculation ofasphaltenes due
30、to incompatibility by assessing the compatibil-ity of fuels beforehand.NOTE 3See Appendix X1 for an example of prediction of compat-ibility.6. Interferences6.1 High content of insoluble inorganic matter (sediment)has some interference in this test method. In this case, theinsoluble matter shall be r
31、emoved by filtration according toTest Method D 4870.6.2 The presence of wax, present in paraffinic crudes orfuels from such crudes, does not interfere.7. Apparatus7.1 Integrated Automated Analytical MeasurementSystemThis test method uses an integrated automated ana-lytical measurement system5compris
32、ed of a PCbased com-puter and two titration stations (Fig. 1). See Annex A1 fordetailed information.3Berryman, T. J., and Lewis, C. P. G., “The Stability of Residual Fuels. Theoryand Practice of the Shell Concept,” 16th CIMAC Conference, Oslo, 1985.4Berg van den, F. G. A., “Developments in Fuel Oil
33、Blending,” IASH 7thInternational Conference, Graz, Austria, 2000.5The following instrument has been found satisfactory for this purposeAutomated Stability Analyser available from Zematra, 3194 DG Hoogvliet, TheNetherlands. If you are aware of alternative suppliers, please provide this informa-tion t
34、o ASTM International Headquarters. Your comments will receive carefulconsideration at a meeting of the responsible technical committee, which you mayattend.D70600527.2 The computer controls test sequencing, acquires andaccumulates optical probe signal data, provides processingcalculations, and autom
35、atically produces a report of importanttest parameters. The computer is capable of controlling one ortwo independent titration stations.7.3 Each titration station consists of the following:7.3.1 Automatic titration unit,7.3.2 Heater,7.3.3 Magnetic stirrer,7.3.4 Optical probe, and7.3.5 Reaction cell
36、plus lid.7.4 Magnetic Stirrer/Hotplate, thermostatically controlled.7.5 Stirring Bar, magnetic, PFTE-coated, 25 mm in length.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the sp
37、ecifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8
38、.2 Asphaltene Solution (3 g/L)Dissolve 0.15 g of dryasphaltenes in 1-methylnaphthalene and dilute to 50 mL. Aprocedure to obtain asphaltenes is described in Appendix X2.Prepare fresh daily, as needed.8.3 Cetane (n-Hexadecane).(WarningIrritating to respi-ratory system and skin.)8.4 Cleaning Solvent,
39、technical grade, 95 % purity, forcleaning. It consists of one of the following:8.4.1 Tetrahydrofuran, stabilized. (WarningExtremelyflammable. Irritating to eyes and respiratory system.)8.4.2 Toluene.(WarningFlammable. Health Hazard.)8.4.3 Xylene.(WarningFlammable. Harmful by inhala-tion and in conta
40、ct with skin. Irritating to skin.)8.5 n-Heptane.(WarningFlammable. Vapor harmful. Va-por may cause flash fire.)8.6 1-Methylnaphthalene.(WarningHarmful if swal-lowed. Irritating to skin.)8.7 Quality Control (QC) Sample, a stable and homoge-neous residual fuel oil. The QC sample contains at least 1mas
41、s % asphaltenes and has approximate viscosities in therange of 180 to 380 mm2/s at 50C.9. Sampling and Test Specimens9.1 Sampling:6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the Americ
42、an Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Titration Stations of Integrated Automated Analytical Measurement SystemD7060053
43、9.1.1 Obtain samples in accordance with Practices D 4057or D 4177.9.1.2 Samples of very viscous materials may be warmeduntil they are reasonably fluid before they are sampled.9.1.3 Store samples prior to taking test specimens at ambi-ent temperatures.9.2 Test Specimen Preparation:9.2.1 Sample Fuel T
44、emperatureWarm viscous samplesuntil they can be mixed readily before opening the storagecontainer. For fuels with a high wax content (high pour point)the temperature shall be at least 15C above the pour point.9.2.2 Shake or mix the sample thoroughly. If the samplecontains a high content of insoluble
45、 matter, filter the samplethrough a 47-mm diameter glass fiber filter medium (such asWhatman Grade GF/A) using the Test Method D 4870 filtra-tion apparatus.9.2.3 Preparation of Six Specimen BlendsVisually checkthe reaction cell and the lid for cleanliness. Dissolve specimenin 1-methylnaphthalene in
46、several different ratios of solventaccording to Table 1. Prepare the blends shortly before the testprocedure. Generally follow the sequence: (1) prepare and testBlends A1 and B1, (2) prepare and test Blends A2 and B2, and(3) prepare and test Blends C, and D.NOTE 4Blends A1 and B1 can be omitted when
47、 the coarse determi-nations are skipped. See also 12.1.1.1.9.2.3.1 Weigh, according to Table 1, specimen to the nearest0.01 g into a clean reaction cell and add a PFTE-coatedmagnetic stirring bar. Place the reaction cell in the center of thepreheated (approximately 150C) magnetic stirrer/hotplate an
48、dswitch on the magnetic stirrer.Allow the specimen to warm up,until its viscosity is low enough to obtain a smooth stirringperformance.9.2.3.2 Add, according to Table 1, while continuouslystirring, an appropriate volume of 1-methylnaphthalene to thenearest 0.01 mL.9.2.3.3 Put the lid in place. Initi
49、ate the test procedure (12.3)within 10 min.NOTE 5Never use excessive force when placing the lid in place.10. Preparation of Apparatus10.1 Prepare the instrument for operation in accordancewith the manufacturers instructions.710.2 Inspect the optical probes glass surface for cleanlinessand damage before use. Connect the optical probes to therespective apparatus titration station. Place the optical probesin the holder at the back of the corresponding titration station.10.3 Cleaning InstructionsPerform the following clean-ing procedure a
