ASTM D7900-17 Standard Test Method for Determination of Light Hydrocarbons in Stabilized Crude Oils by Gas Chromatography1, 2.pdf

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1、Designation: D7900 17Designation: 601Standard Test Method forDetermination of Light Hydrocarbons in Stabilized CrudeOils by Gas Chromatography1,2This standard is issued under the fixed designation D7900; the number immediately following the designation indicates the year oforiginal adoption or, in t

2、he 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*1.1 This test method specifies a method to determine theboiling range distribution of hy

3、drocarbons in stabilized crudeoil up to and including n-nonane. A stabilized crude oil isdefined as having a Reid Vapor Pressure equivalent to or lessthan 82.7 kPa. The results of this test method can be combinedwith those from Test Method D7169 and IP 545 to give a fullboiling point distribution of

4、 a crude oil. See Test MethodD7169 (IP 545) for merging of these results to give a full crudeanalysis.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation purposes only.1.3 This standard does not purport to address all of th

5、esafety concerns, 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.1.4 This international standard was developed in accor

6、-dance with 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

7、 Standards:3D323 Test Method for Vapor Pressure of Petroleum Products(Reid Method)D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5134 Test Method for Detailed Analysis of PetroleumNaphthas through n-Nonane

8、 by Capillary Gas Chroma-tographyD6729 Test Method for Determination of Individual Com-ponents in Spark Ignition Engine Fuels by 100 MetreCapillary High Resolution Gas ChromatographyD6730 Test Method for Determination of Individual Com-ponents in Spark Ignition Engine Fuels by 100MetreCapillary (wit

9、h Precolumn) High-Resolution Gas Chro-matographyD6733 Test Method for Determination of Individual Com-ponents in Spark Ignition Engine Fuels by 50-MetreCapillary High Resolution Gas ChromatographyD7169 Test Method for Boiling Point Distribution ofSamples with Residues Such as Crude Oils and Atmo-sph

10、eric and Vacuum Residues by High Temperature GasChromatographyE355 Practice for Gas Chromatography Terms and Relation-ships2.2 Energy Institute Standards:4IP 545 Crude Petroleum and Petroleum ProductsDetermination of Boiling Range Distribution of Crude OilIP 475 Manual SamplingIP 476 Automatic Pipel

11、ine Sampling1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current edition approved Oct. 1, 2017. Published October 2017. Originallyapproved i

12、n 2013. Last previous edition approved in 2013 as D7900 131. DOI:10.1520/D7900-17.2This standard has been developed through the cooperative effort betweenASTM and the Energy Institute, London. The IP and ASTM logos imply that theASTM and IP standards are technically equivalent, but their use does no

13、t imply thatboth standards are editorially identical.3For 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.4Informa

14、tion on Energy Institute Standards can be obtained from the EnergyInstitute at www.energyinst.org.*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 StatesThis international stand

15、ard was developed in accordance 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.12.3 IS

16、O Standard:5ISO 4259 Petroleum ProductsDetermination and Applica-tion of Precision Data in Relation to Methods of Test3. Terminology3.1 DefinitionsThis test method makes reference to manycommon gas chromatographic procedures, terms, and relation-ships. Detailed definitions can be found in Practice E

17、355.4. Summary of Test Method4.1 An amount of internal standard is quantitatively addedto an aliquot of the stabilized crude oil. A portion of thismixture is injected into a pre-column in series via a splitterwith a capillary analytical column. When the n-nonane hasquantitatively passed to the analy

18、tical column, the pre-columnis back-flushed to vent the higher boiling components. Theindividual components are identified by comparison withreference chromatograms and a database of hydrocarbon com-pounds (see Appendix X1). The boiling point distribution up toand including n-nonane (n-C9) is calcul

19、ated.5. Significance and Use5.1 Knowledge of the boiling point distribution of stabilizedcrude oils is important for the marketing, scheduling, andprocessing of crude oil in the petroleum industry. Test MethodD7169 and IP 545 purport to give such a distribution in crudeoils, but are susceptible to s

20、ignificant errors in the light endsportion of the distribution as well as in the mass recovery of thewhole crude oil due to the interference imposed by the diluentsolvent. This test method allows for more accurate determina-tion of the front end of the boiling point distribution curve, inaddition to

21、 providing important C1 to C9 (nonane) componentlevel information, and more accurate mass recovery at C9(nonane).6. Apparatus6.1 Gas Chromatograph, with the operational characteris-tics given in Table 1.6.2 InletA temperature programmable vaporizing (PVT)or split/splitless inlet.6.2.1 Carrier Gas Pn

22、eumatic ControlConstant carrier gaspressure or flow control is required.6.3 ColumnA fused silica-bonded polydimethylsiloxanecoated capillary column and pre-column are employed. SeeTable 1 for suggested columns. The analytical column shallelute hydrocarbons in a boiling point order. The eluate from t

23、heinjector passes through the pre-column before eluting onto theanalytical column.6.4 Data SystemA computer-based chromatography datasystem capable of accurately and repeatedly measuring theretention time and areas of eluting peaks. The system shall beable to acquire data at a rate adequate to accur

24、ately measure 10to 20 points around an individual peak. For the acceleratedmethods (see Table 1), a sampling rate of at least 20 Hz isrecommended.6.5 Sample IntroductionSample introduction by means ofan automatic injection is highly recommended.6.6 Flame Ionization Detector (FID), with sufficient se

25、nsi-tivity to detect 0.01 % mass n-heptane with a signal to noise ofgreater than five. When operating at this sensitivity level,detector stability shall be such that a baseline drift of not morethan 1 % per hour is obtained. The detector shall be connectedto the column so as to avoid any cold spots.

26、 The detector shallbe capable of operating at a temperature equivalent to themaximum column temperature used.6.7 Pre-Column Configurations:6.7.1 Heated Valve Switching Box ConfigurationFor theisothermal 1 m pre-column, a heated valve box is needed withits own temperature control. The box will contai

27、n an automatedsix-port valve, which is used to back-flush the pre-column. Thesix-port valve should be made out of material that will not be5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.TABLE 1 Typical Chromatographic Co

28、nditionsPre-column Pre-column Analytical AcceleratedA B AnalyticalColumn Lengthmetres 1.0 m 0.075 m 50 or 100 m 40 mColumn Internal Diametermm 2 mm 2.5 mm 0.25 mm 0.10 mmPhase Loading 5 % 10 %Film Thickness 0.5 umInjection Volume 0.1 L 0.1 LInjector Split Ratio 100 : 1 600 : 1Injector Temperature 30

29、0 C 100 CPre-column Temperature 200 C 100 CInjector Prog. Rate C/min 50 C minFinal Injector Temperature 300 CInitial Oven Temperature 35 C 35 CHold Time 30 min 2.6 minOven Program Rate C/min 2Cmin 50Cmin 45 C(hold time 3 min)5Cmin 60 C(hold time 3 min)9.5 C min Final Oven Temperature 200 C (hold tim

30、e 20 min) 200 C (hold time 1 min)Flame Ionization Detector 300 C 300 CD7900 172corroded by the sample (some crude oils contain high amountsof sulfur components). The valve shall be situated in a heatedisothermal oven and be attached to the injector, pre-column,splitter, analytical column, and the de

31、tector without any coldspots. An example configuration is given in Fig. X2.1 inAppendix X2. Alternatively, a Dean Switch type back-flush ofthe petroleum may also be employed in place of a rotary valve.6.7.2 Injection Port Back-Flush ConfigurationA tempera-ture programmable injection port capable of

32、containing a7.5 cm pre-column, and this injection port must be equippedwith a back-flush option. This injector can be connecteddirectly to the capillary column (Fig. X2.2, Appendix X2)orvia a splitter (Fig. X2.3, Appendix X2).6.8 Analytical Balance, capable of weighing with an accu-racy of 0.1 mg.7.

33、 Reagents and Materials7.1 Gas Chromatograph GasesAll of the following gasesshall have a purity of 99.995 % (V V) or greater. (WarningGases are compressed. Some are flammable, and all gases areunder high pressure.)NOTE 1These specifications can be obtained by proper use of filteringdevices and meeti

34、ng the FID specifications in 6.6.7.1.1 Carrier GasHelium or hydrogen is required. Anyoxygen present shall be removed, for example, by a suitablechemical filter. If hydrogen is employed as a carrier gas, theuser is advised to follow all manufacturers safety guidelinesfor its use. (WarningHydrogen is

35、an extremely flammablegas under high pressure.)7.1.2 Detector Combustion Gases, Air, Hydrogen, andMake-up Gas (Helium or Nitrogen). (WarningHydrogen isan extremely flammable gas under high pressure.) (WarningCompressed air is a gas under high pressure and supportscombustion.)7.2 Internal StandardThe

36、 internal standard shall havebaseline resolution from any adjacent eluting peaks. Hexene-1or 3,3dimethylbutene-1 (99 % pure) have been found to besuitable.7.3 Valve Timing Mixture/Splitter Linearity MixA quanti-tative mixture of approximately 1 % mass of each normalalkane from pentane to decane in h

37、exadecane (99+ % purity).Accurately record the mass (g) of each normal alkane as wellas the hexadecane solvent and calculate the actual mass percentof each alkane in the mixture.7.4 Viscosity Agent, Carbon disulfide, 99+ % pure,(WarningExtremely flammable and toxic liquid) is used asa viscosity redu

38、ction agent in the preparation of samples.8. Sampling8.1 Samples to be analyzed by this test method must beobtained using the procedures outlined in Practice D4057 orPractice D4177 (IP 475 and IP 476, respectively).8.2 The test specimen to be analyzed must be homogeneousand free of dust or undissolv

39、ed material.9. Preparation of Apparatus9.1 ChromatographPlace in service according to manu-facturers instructions. Typical operating conditions are givenin Table 1.9.2 Column PreparationCondition analytical columns inaccordance with manufacturers instructions.9.3 System Performance Specification:9.3

40、.1 SkewnessDetermine the skew of the n-hexane peakby measuring the width of the leading part of the peak at 5 %peak height (A) and the width of the following part of the peakat 5 % peak height (B). The ratio (B)/(A) shall be not less than1 or more than 4 (see Fig. 1).9.3.2 Column ResolutionDetermine

41、 the resolution be-tween the internal standard and the nearest n-paraffin peak.R 5 2 3 t2 2 t1! 1.699w1 1 w2! (1)where:R = the column resolution,t1 = the retention time of the first peak (peak 1),t2 = the retention time of the second peak (peak 2),w1 = the peak width at half height of peak 1, andw2

42、= the peak width at half height of peak 2.For example, if Hexene-1 is used as the internal standard, theresolution is determined between Hexene-1 and n-hexane. Theresolution shall be at least 2.0.9.3.3 Detector Response Factor CalculationsCalculatethe flame ionization detector response factor relati

43、ve tomethane, which is considered to have a response factor of unity(1), for each hydrocarbon group type of a particular carbonnumber using Eq 2.RRf 5Caw3 Cn!1Haw3 Hn!# 30.7487Caw3 Cn!(2)where:RRf = relative response factor for a hydrocarbon typegroup of a particular carbon number,Caw= atomic mass o

44、f carbon, 12.011,Cn= number of carbon atoms in the hydrocarbon typegroup, of a particular carbon number,FIG. 1 Calculation of Peak Skewness (see 9.3.1)D7900 173Haw= atomic mass of hydrogen, 1.008,Hn= number of hydrogen atoms in the hydrocarbon typegroup of a particular carbon number, and0.7487 = fac

45、tor to normalize the result to a methane re-sponse of unity, (1).9.3.4 Determination of Back-Flush TimeWith the pre-column and analytical column in series, inject an aliquot of thepre-column switch test mixture (7.3) and determine the ratio ofthe alkanes.9.3.4.1 Non-Accelerated Analytical ColumnSet

46、theswitching time to one minute and repeat the analysis. Increaseor decrease the valve time to ensure the complete recovery ofthe highest alkane required (for example, n-nonane) and partialrecovery of the next alkane (for example, decane). (Seeexample chromatogram (Fig. 3).)9.3.4.2 Accelerated Analy

47、tical ColumnSet the switchingtime to 30 s and repeat the analysis. Increase or decrease thevalve time to ensure the recovery of the highest alkane required(for example, n-nonane) and partial recovery of the next alkane(for example, n-decane). (See example chromatogram (Fig. 3).)9.3.5 Split Injection

48、 LinearityFor systems utilizing splitinjection, injector linearity must be established to determineproper quantitative parameters and limits.9.3.5.1 Set the injector temperature and split ratio to theoperating values as indicated in Table 1 for split inlets.9.3.5.2 Inject 0.1 L of the splitter linea

49、rity mixture (7.3)into the system.9.3.5.3 Calculate the normalized area % of the n-C5 throughn-C9 paraffins using Eq 3:Corrected Normalized Area %Cn100 3 Area Cn3 RRf Cn! TA# (3)where:Area Cn= integrated peak area of normal alkane Cn,RRf Cn= theoretical relative response factor for Cn(Eq 2),andTA = sum of RRf corrected peak areas from C5to C9.9.3.5.4 The corrected normalized area percent of eachnormal alkane must agree within 10 % or better from theirgravimetric values after the back-fl