1、Designation: D7112 12 (Reapproved 2017)Standard Test Method forDetermining Stability and Compatibility of Heavy Fuel Oilsand Crude Oils by Heavy Fuel Oil Stability Analyzer (OpticalDetection)1This standard is issued under the fixed designation D7112; the number immediately following the designation
2、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. Scope1.1 This test method covers an automated p
3、rocedure involv-ing titration and optical detection of precipitated asphaltenesfor determining the stability and compatibility parameters ofrefinery residual streams, residual fuel oils, and crude oils.Stability in this context is the ability to maintain asphaltenes ina peptized or dissolved state a
4、nd not undergo flocculation orprecipitation. Similarly, compatibility relates to the property ofmixing two or more oils without precipitation or flocculation ofasphaltenes.1.2 This test method is applicable to residual products fromatmospheric and vacuum distillation, from thermal, catalytic,and hyd
5、rocracking processes, to products typical of Specifica-tions D396, Grades No. 5L, 5H, and 6, and D2880, Grades No.3-GT and 4-GT, and to crude oils, providing these productscontain 0.05 mass % or greater concentration of asphaltenes.1.3 This test method is not relevant to oils that contain lessthan 0
6、.05 % asphaltenes, and would be pointless to apply tounstable oils that already contain flocculated asphaltenes.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 c
7、oncerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance wi
8、th internationally recognized principles on standard-ization established in the Decision on Principles 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 Standard
9、s:2D396 Specification for Fuel OilsD2880 Specification for Gas Turbine Fuel OilsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum Products, LiquidFuels, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6
10、299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6560 Test Method for Determination of Asphaltenes (Hep-tane Insolubles) in Crude Petroleum and Petroleum Prod-ucts3. Terminology3.1 Definitions:3.1.1 For defini
11、tions of some terms used in this test method,such as crude oil, repeatability, reproducibility, and residualfuel oil, refer to Terminology D4175.3.1.2 asphaltenes, n(rarely used in the singular), in petro-leum technology, represent an oil fraction that is soluble in aspecified aromatic solvent but s
12、eparates upon addition of anexcess of a specified paraffinic solvent.3.1.2.1 DiscussionIn this test method, the aromatic sol-vent is xylene and the paraffinic solvent is n-heptane.3.1.3 compatibility, nof crude oils and of heavy fuel oils,the ability of two or more crude oils or fuel oils to be blen
13、dedtogether within specified ratios without evidence of separation,such as flocculation or separation of asphaltenes.3.1.4 flocculation, nof asphaltenes in crude oils or heavyfuel oils, the aggregation of colloidally dispersed asphaltenesinto larger, visible masses that may or may not settle.1This t
14、est method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.14 on on Stability, Cleanliness and Compatibility of LiquidFuels.Current edition approved Oct. 1, 2017. Published November 2017. Originall
15、yapproved in 2005. Last previous edition approved in 2012 as D711212. DOI:10.1520/D7112-12R17.2For 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
16、 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 accordance with internationally recognized principles on standardization established in the Decision on Princ
17、iples for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.5 stability reserve, nof crude oils, heavy fuel oils, andresidual streams containing asphaltenes, the property of an oilto maintain
18、asphaltenes in a peptized (colloidally dispersed)state and prevent their flocculation when stored or whenblended with other oils.3.1.5.1 DiscussionAn oil with a high stability reserve canbe stored for a long period of time or blended with a range ofother oils without flocculation of asphaltenes.3.2
19、Definitions of Terms Specific to This Standard:3.2.1 aromatic solvent equivalent (xylene equivalent), SE,nthe lowest aromatic solvent (xylene) content, expressed asa volume %, in a mixture containing aromatic and paraffinicsolvents (xylene and n-heptane) which, when mixed with oil,will not result in
20、 flocculation of asphaltenes. See flocculationratio.3.2.1.1 DiscussionSE is defined as FR5/1multiplied by100 %, as shown in Eq 2.3.2.2 evaporation correction coeffcient, nthe rate ofevaporation of aromatic solvent (xylene) from the sample cup,measured in grams per hour.3.2.3 flocculation ratio (FR),
21、 nthe lowest aromatic solvent(xylene) concentration, expressed as a proportion of xylene toxylene plus n-heptane which, when mixed with an oil, will notresult in flocculation of asphaltenes. See 15.1, Eq 1.3.2.4 FR5/1,nthe flocculation ratio at a dilution of 5 mL ofxylene and n-heptane solvent mixtu
22、re to1gofoil.3.2.4.1 DiscussionThe ratio 5 to 1 is used internally by anumber of oil companies involved with the stability andcompatibility of heavy fuel oils and crude oils. This ratio ischosen so that a P-value of six represents an FR5/1of zero.3.2.5 insolubility number, IN,na crude oil blending m
23、odelparameter which can be used to determine if blends of oils arecompatible or incompatible. See solubility blending number.3.2.5.1 DiscussionInsolubility numbers for individual oilsare determined and calculated from the density of the oil,aromatic solvent equivalent value and volume of paraffinics
24、olvent (n-heptane) that can be added to 5 mL of oil withoutasphaltene precipitation. The equations are given under Calcu-lation of Results (see 15.2).3.2.6 maximum flocculation ratio, FRmax, nof asphaltenesin residual fuel oils and crude oils, the minimum requiredsolvency power of a solvent mixture,
25、 expressed as a ratio byvolume of aromatic solvent (xylene) to aromatic solvent plusparaffinic solvent (n-heptane) to keep the asphaltenes in an oilcolloidally dispersed.3.2.6.1 DiscussionFRmaxis determined from a plot offlocculation ratios versus the oil concentration in solvent,extrapolated to inf
26、inite dilution of the sample at the y-axis(where (1/X)=0.SeeEq 3).3.2.7 oil matrix, nthat portion of a sample of heavy fueloil or crude oil that surrounds and colloidally disperses theasphaltenes.3.2.7.1 DiscussionFor purposes of this test method, an oilsample is considered to be composed of an oil
27、matrix (some-times called an oil medium) and asphaltenes.3.2.8 P-value, nof refinery residual steams, residual fueloils and crude oils, an indication of the stability or availablesolvency power of an oil with respect to precipitation ofasphaltenes.3.2.8.1 DiscussionSince the equation defining P-valu
28、e isP =(1+Xmin), where Xminis the minimum volume of paraffinicsolvent, n-heptane, (in mL) needed to be added to1gofoiltoresult in flocculation of asphaltenes, the smallest P-value is 1,which means the oil is unstable and can precipitate asphalteneswithout addition of any paraffinic solvent. A higher
29、 P-valueindicates that an oil is more stable with respect to flocculationof asphaltenes. P-value by this test method relates specificallyto xylene and n-heptane as the aromatic and paraffinic solvents,respectively.3.2.9 Pa,nthe P-value of an asphaltene, which is thepeptizability or ability of an asp
30、haltene to remain colloidallydispersed.3.2.10 Po,nthe P-value of an oil matrix. See oil matrix.3.2.11 peptize, vof an oil or cutter stock, to dissolve anasphaltene or to maintain an asphaltene in colloidal dispersion.3.2.12 solubility blending number, SBN,na crude oilblending model parameter which c
31、an be used to determine ifblends of oils are incompatible or compatible. See insolubilitynumber.3.2.12.1 DiscussionSolubility blending numbers for indi-vidual oils are determined and calculated from the density ofthe oil, aromatic solvent equivalent value, and volume ofparaffinic solvent that can be
32、 added to 5 mL of oil withoutasphaltene precipitation. The equations are given under Calcu-lation of Results (see 15.2).3.2.13 step size, nthe volume in mL of each portion ofn-heptane added to the stock solution in the course of the testprocedure.3.2.14 stock solution, na solution of a sample dissol
33、ved ina specific amount of xylene.3.3 Symbols:FR = flocculation ratioFR5/1= flocculation ratio at a dilution of 5 mL solution(xylene plus n-heptane) to1gofoilFRmax= maximum flocculation ratioIN= insolubility numberP = the P-value of an oilPa= the P-value of an asphaltenePo= the P-value or peptizing
34、power of an oil matrixSBN= solubility blending numberSE = xylene equivalent, volume %Xmin= n-heptane consumption of undiluted oil, in mL/g ofoil4. Summary of Test Method4.1 Stability and compatibility parameters are determinedby titration and optical detection of precipitated asphaltenes. Astock sol
35、ution is prepared and three different mixtures of thesample oil plus xylene are titrated with n-heptane to causeprecipitation of asphaltenes. The titrated mixture is continu-ously circulated through an optical detector which detectsprecipitated asphaltenes by back-scattering of visible light. TheD71
36、12 12 (2017)2amounts of oil, xylene, and n-heptane are used to calculatestability parameters: solvent equivalent, P-value, and FR5/1.Ifthe density of a crude oil sample is known, then the compat-ibility parameters (SBNand IN) of the crude oil may also becalculated.5. Significance and Use5.1 Automati
37、c determination of stability parameters using alight back-scattering technique improves accuracy and re-moves human errors. In manual testing, operators have tovisually compare oil stains on pieces of filter paper to deter-mine if asphaltenes have been precipitated.5.2 Refinery thermal and hydrocrac
38、king processes can berun closer to their severity limits if stability parameters can becalculated more accurately. This gives increased yield andprofitability.5.3 Results from the test method could be used to set astandard specification for stability parameters for fuel oils.5.4 The compatibility pa
39、rameters of crude oils can be usedin crude oil blending in refineries to determine, in advance,which crude oil blends will be compatible and thus can be usedto minimize plugging problems, unit shut downs, and mainte-nance costs. Determination of crude oil compatibility param-eters also enables refin
40、eries to select crude oil mixtures moreeconomically.5.5 This test method can measure stability and compatibilityparameters, and determine stability reserve on different blendsfor particular applications to optimize the blending, storage,and use of heavy fuel oilsNOTE 1Users of this test method would
41、 normally use stability andcompatibility parameters to determine stability reserve of residualproducts, fuel blends and crude oils. However, the interpretation ofstability, stability reserve and compatibility is heavily use dependent,andis beyond the scope of this test method.6. Interferences6.1 Fre
42、e water present in the oil can cause difficulties withthe optical detector and should be removed by centrifugingprior to testing.6.2 Solid particles, such as coke or wax particles, mud,sand, or catalyst fines, in the oil will not affect the opticaldetector or interfere with the results.7. Apparatus7
43、.1 PORLA Heavy and Crude Oil Stability and Compatibil-ity Analyzer3,4See Figs. 1 and 2.7.1.1 A portion of the apparatus is shown diagrammaticallyin Fig. 2 and is comprised of the following parts:7.1.1.1 Sample Cup, light weight, inert cups designed to fitthe sample carousel, with a smooth, flat bott
44、om, volumeapproximately 100 mL. Typically, aluminum cups have beenused.7.1.1.2 Sample Carousel, typically a four-position samplecup holder delivering the sample cups sequentially to themeasurement position.7.1.1.3 Mixer Lift System, vertically moving lift system,forming a seal with the sample cup in
45、 the measurementposition and incorporating a mechanical stirrer which starts torotate when the seal is made. It also incorporates delivery linesfor n-heptane and xylene addition, the circulation line forpassing the sample through the detector and the exhaust line,which empties the sample cup after a
46、nalysis.7.1.1.4 Aromatic Solvent Pump, accurate and adjustableceramic piston pump, capable of delivering xylene at a rate of0.01 mL s to 0.5 mL/s.7.1.1.5 Paraffnic Solvent Pump, accurate and adjustableceramic piston pump, capable of delivering n-heptane at a rateof 0.01 mL s to 0.5 mL/s.7.1.1.6 Circ
47、ulation Pump, accurate and adjustable ceramicpiston pump used to circulate the sample under test through thedetector system.7.1.1.7 Exhaust Pump, accurate and adjustable ceramicpiston pump used to empty the sample cup at the end of themeasurement.7.1.1.8 Detector System, (see Fig. 3) optical detecto
48、rthrough which the sample solution is continuously circulated.The detector is composed of a visible light source and aphotodiode for recording the light reflecting from asphalteneparticles in the test sample.7.1.1.9 Hot Plate, a temperature controlled heating systemmay be located below the sample cu
49、ps, which will warm up thesample so that the titration may be performed at an elevatedtemperature. The temperature of the hot plate should beadjustable between 20 C and 100 C.7.1.2 Computer, controls the measurement and calibrationprograms and is an interface between the operator and theanalyzer.7.1.3 PORLA Step Measurement Screen, computer display,allowing data about the sample and operator to be input as wellas showing the results of each titration (see Fig. 4).7.1.4 Parameter Screen, computer display, allows all of themeasurement cycl
