ASTM D7112-2018 red 8125 Standard Test Method for Determining Stability and Compatibility of Heavy Fuel Oils and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical Detection).pdf

1、Designation: D7112 12 (Reapproved 2017)D7112 18Standard 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 desi

2、gnation 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. Scope Scope*1.1 This test method covers

3、 an automated procedure involving titration and optical detection of precipitated asphaltenes fordetermining the stability and compatibility parameters of refinery residual streams, residual fuel oils, and crude oils. Stability inthis context is the ability to maintain asphaltenes in a peptized or d

4、issolved state and not undergo flocculation or precipitation.Similarly, compatibility relates to the property of mixing two or more oils without precipitation or flocculation of asphaltenes.1.2 This test method is applicable to residual products from atmospheric and vacuum distillation, from thermal

5、, catalytic, andhydrocracking processes, to products typical of Specifications D396, Grades No. 5L, 5H, and 6, and D2880, Grades No. 3-GT and4-GT, and to crude oils, providing these products contain 0.05 mass % or greater concentration of asphaltenes.1.3 This test method is not relevant to oils that

6、 contain less than 0.05 % asphaltenes, and would be pointless to apply to unstableoils that already contain flocculated asphaltenes.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to addr

7、ess all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.6 This international standard was develop

8、ed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents

9、2.1 ASTM Standards:2D396 Specification for Fuel OilsD2880 Specification for Gas Turbine Fuel OilsD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD4177 Practice for Automatic Sampling of Petroleum and

10、Petroleum ProductsD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System PerformanceD6560 Test Method for Determination of Asphaltenes (Heptane Insolubles) in Crude Petroleum and Petroleum Products3. Terminology3.1 Definit

11、ions:3.1.1 For definitions of some terms used in this test method, such as crude oil, repeatability, reproducibility, and residual fueloil, refer to Terminology D4175.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the dire

12、ct responsibility of SubcommitteeD02.14 on on Stability, Cleanliness and Compatibility of Liquid Fuels.Current edition approved Oct. 1, 2017July 1, 2018. Published November 2017July 2018. Originally approved in 2005. Last previous edition approved in 20122017 asD7112D7112 12 (2017).12. DOI: 10.1520/

13、D7112-12R17.10.1520/D7112-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM sta

14、ndard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cas

15、es only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 asphalten

16、es, n(rarely used in the singular), in petroleum technology, represent an oil fraction that is soluble in a specifiedaromatic solvent but separates upon addition of an excess of a specified paraffinic solvent.3.1.2.1 DiscussionIn this test method, the aromatic solvent is xylene and the paraffinic so

17、lvent is n-heptane.3.1.3 compatibility, nof crude oils andor of heavy fuel oils, the ability of two or more crude oils or fuel oils to be blendedblend together within specified ratios certain concentration ranges without evidence of separation, such as flocculation orseparation of asphaltenes. the f

18、ormation of multiple phases.3.1.3.1 DiscussionIncompatible heavy fuel oils or crude oils, when mixed or blended, result in the flocculation or precipitation of asphaltenes. Someoils may be compatible within certain concentration ranges in specific mixtures, but incompatible outside those ranges.3.1.

19、4 flocculation, nof asphaltenes infrom crude oils or heavy fuel oils, the aggregation of colloidally dispersed asphaltenesinto larger, visiblevisibly larger masses thatwhich may or may not settle.3.1.5 stability reserve, nof crude oils, heavy fuel oils, and residual streams containing asphaltenes, t

20、he property of an oil tomaintain asphaltenes in a peptized (colloidally dispersed) state and prevent their flocculation when stored or when blended withother oils.3.1.5.1 DiscussionAn oil with a high stability reserve can be stored for a long period of time or blended with a range of other oils with

21、out flocculationof asphaltenes.3.2 Definitions of Terms Specific to This Standard:3.2.1 aromatic solvent equivalent (xylene equivalent), SE, nthe lowest aromatic solvent (xylene) content, expressed as avolume %, in a mixture containing aromatic and paraffinic solvents (xylene and n-heptane) which, w

22、hen mixed with oil, will notresult in flocculation of asphaltenes. See flocculation ratio.3.2.1.1 DiscussionSE is defined as FR5/1 multiplied by 100 %, as shown in Eq 2.3.2.2 evaporation correction coeffcient, nthe rate of evaporation of aromatic solvent (xylene) from the sample cup, measuredin gram

23、s per hour.3.2.3 flocculation ratio (FR), nthe lowest aromatic solvent (xylene) concentration, expressed as a proportion of xylene toxylene plus n-heptane which, when mixed with an oil, will not result in flocculation of asphaltenes. See 15.1, Eq 1.3.2.4 FR5/1, nthe flocculation ratio at a dilution

24、of 5 mL of xylene and n-heptane solvent mixture to 1 g of oil.3.2.4.1 DiscussionThe ratio 5 to 1 is used internally by a number of oil companies involved with the stability and compatibility of heavy fuel oilsand crude oils. This ratio is chosen so that a P-value of six represents an FR5/1 of zero.3

25、.2.5 insolubility number, IN, na crude oil blending model parameter 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 oils are determined and calculated from the density of the oil, aro

26、matic solvent equivalent valueand volume of paraffinic solvent (n-heptane) that can be added to 5 mL of oil without asphaltene precipitation. The equations aregiven under Calculation of Results (see 15.2).3.2.6 maximum flocculation ratio, FRmax, nof asphaltenes in residual fuel oils and crude oils,

27、the minimum required solvencypower of a solvent mixture, expressed as a ratio by volume of aromatic solvent (xylene) to aromatic solvent plus paraffinic solvent(n-heptane) to keep the asphaltenes in an oil colloidally dispersed.D7112 1823.2.6.1 DiscussionFRmax is determined from a plot of flocculati

28、on ratios versus the oil concentration in solvent, extrapolated to infinite dilution ofthe sample at the y-axis (where (1/X) = 0. See Eq 3).3.2.7 oil matrix, nthat portion of a sample of heavy fuel oil or crude oil that surrounds and colloidally disperses theasphaltenes.3.2.7.1 DiscussionFor purpose

29、s of this test method, an oil sample is considered to be composed of an oil matrix (sometimes called an oil medium)and asphaltenes.3.2.8 P-value, nof refinery residual steams, residual fuel oils and crude oils, an indication of the stability or available solvencypower of an oil with respect to preci

30、pitation of asphaltenes.3.2.8.1 DiscussionSince the equation defining P-value is P = (1 + Xmin), where Xmin is the minimum volume of paraffinic solvent, n-heptane, (in mL)needed to be added to 1 g of oil to result in flocculation of asphaltenes, the smallest P-value is 1, which means the oil is unst

31、ableand can precipitate asphaltenes without addition of any paraffinic solvent.Ahigher P-value indicates that an oil is more stable withrespect to flocculation of asphaltenes. P-value by this test method relates specifically to xylene and n-heptane as the aromatic andparaffinic solvents, respectivel

32、y.3.2.9 Pa, nthe P-value of an asphaltene, which is the peptizability or ability of an asphaltene to remain colloidally dispersed.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 an asphaltene or to maintain an asphaltene in colloidal d

33、ispersion.3.2.12 solubility blending number, SBN, na crude oil blending model parameter which can be used to determine if blends ofoils are incompatible or compatible. See insolubility number.3.2.12.1 DiscussionSolubility blending numbers for individual oils are determined and calculated from the de

34、nsity of the oil, aromatic solventequivalent value, and volume of paraffinic solvent that can be added to 5 mL of oil without asphaltene precipitation. The equationsare given under Calculation of Results (see 15.2).3.2.13 step size, nthe volume in mL of each portion of n-heptane added to the stock s

35、olution in the course of the testprocedure.3.2.14 stock solution, na solution of a sample dissolved in a specific amount of xylene.3.3 Symbols:FR = flocculation ratioFR5/1 = flocculation ratio at a dilution of 5 mL solution (xylene plus n-heptane) to 1 g of oilFRmax = maximum flocculation ratioIN =

36、insolubility numberP = the P-value of an oilPa = the P-value of an asphaltenePo = the P-value or peptizing power of an oil matrixSBN = solubility blending numberSE = xylene equivalent, volume %Xmin = n-heptane consumption of undiluted oil, in mL/g of oil4. Summary of Test Method4.1 Stability and com

37、patibility parameters are determined by titration and optical detection of precipitated asphaltenes. A stocksolution is prepared and three different mixtures of the sample oil plus xylene are titrated with n-heptane to cause precipitation ofasphaltenes. The titrated mixture is continuously circulate

38、d through an optical detector which detects precipitated asphaltenes byback-scattering of visible light. The amounts of oil, xylene, and n-heptane are used to calculate stability parameters: solventequivalent, P-value, and FR5/1. If the density of a crude oil sample is known, then the compatibility

39、parameters (SBN and IN) ofthe crude oil may also be calculated.D7112 1835. Significance and Use5.1 Automatic determination of stability parameters using a light back-scattering technique improves accuracy and removeshuman errors. In manual testing, operators have to visually compare oil stains on pi

40、eces of filter paper to determine if asphalteneshave been precipitated.5.2 Refinery thermal and hydrocracking processes can be run closer to their severity limits if stability parameters can becalculated more accurately. This gives increased yield and profitability.5.3 Results from the test method c

41、ould be used to set a standard specification for stability parameters for fuel oils.5.4 The compatibility parameters of crude oils can be used in crude oil blending in refineries to determine, in advance, whichcrude oil blends will be compatible and thus can be used to minimize plugging problems, un

42、it shut downs, and maintenance costs.Determination of crude oil compatibility parameters also enables refineries to select crude oil mixtures more economically.5.5 This test method can measure stability and compatibility parameters, and determine stability reserve on different blends forparticular a

43、pplications to optimize the blending, storage, and use of heavy fuel oilsNOTE 1Users of this test method would normally use stability and compatibility parameters to determine stability reserve of residual products, fuelblends and crude oils. However, the interpretation of stability, stability reser

44、ve and compatibility is heavily use dependent, and is beyond the scope ofthis test method.6. Interferences6.1 Free water present in the oil can cause difficulties with the optical detector and should be removed by centrifuging prior totesting.6.2 Solid particles, such as coke or wax particles, mud,

45、sand, or catalyst fines, in the oil will not affect the optical detector orinterfere with the results.7. Apparatus7.1 PORLA Heavy and Crude Oil Stability and Compatibility Analyzer3,4See Figs. 1 and 2.7.1.1 A portion of the apparatus is shown diagrammatically in Fig. 2 and is comprised of the follow

46、ing parts:7.1.1.1 Sample Cup, light weight, inert cups designed to fit the sample carousel, with a smooth, flat bottom, volumeapproximately 100 mL. Typically, aluminum cups have been used.7.1.1.2 Sample Carousel, typically a four-position sample cup holder delivering the sample cups sequentially to

47、themeasurement position.7.1.1.3 Mixer Lift System, vertically moving lift system, forming a seal with the sample cup in the measurement position andincorporating a mechanical stirrer which starts to rotate when the seal is made. It also incorporates delivery lines for n-heptane andxylene addition, t

48、he circulation line for passing the sample through the detector and the exhaust line, which empties the samplecup after analysis.7.1.1.4 Aromatic Solvent Pump, accurate and adjustable ceramic piston pump, capable of delivering xylene at a rate of0.01 mLs to 0.5 mL/s.7.1.1.5 Paraffnic Solvent Pump, a

49、ccurate and adjustable ceramic piston pump, capable of delivering n-heptane at a rate of0.01 mLs to 0.5 mL/s.7.1.1.6 Circulation Pump, accurate and adjustable ceramic piston pump used to circulate the sample under test through thedetector system.7.1.1.7 Exhaust Pump, accurate and adjustable ceramic piston pump used to empty the sample cup at the end of themeasurement.7.1.1.8 Detector System, (see Fig. 3) optical detector through which the sample solution is continuously circulated. The detectoris composed of a visible light source and a photo