ASTM D7900-2018e1 Standard Test Method for Determination of Light Hydrocarbons in Stabilized Crude Oils by Gas Chromatography.pdf

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1、Designation: D7900 181Designation: 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

2、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.1NOTESubsection 1.1 was revised editorially in November 2018.1. Scope*1.1 This test method speci

3、fies a method to determine theboiling range distribution of hydrocarbons 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 Metho

4、d D7169 and IP 545 to give a fullboiling point distribution of a crude oil (see Appendix X3).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 thesafety c

5、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.1.4 This international standard was developed in accor-dance wi

6、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

7、s: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 by Capil

8、lary 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 (with Precolu

9、mn) 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-spheric and

10、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 Pipeline Sampl

11、ing2.3 ISO Standard:5ISO 4259 Petroleum ProductsDetermination and Applica-tion of Precision Data in Relation to Methods of Test1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0

12、L on Gas Chromatography Methods.Current edition approved Oct. 1, 2018. Published October 2018. Originallyapproved in 2013. Last previous edition approved in 2017 as D7900 17. DOI:10.1520/D7900-18E01.2This standard has been developed through the cooperative effort betweenASTM and the Energy Institute

13、, London. The IP and ASTM logos imply that theASTM and IP standards are technically equivalent, but their use does not 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 Annu

14、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Information on Energy Institute Standards can be obtained from the EnergyInstitute at www.energyinst.org.5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floo

15、r, New York, NY 10036, http:/www.ansi.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 standard was developed in accordance with internationally rec

16、ognized 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.13. Terminology3.1 DefinitionsThis test method makes reference

17、to manycommon gas chromatographic procedures, terms, and relation-ships. Detailed definitions can be found in Practice E355.4. 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-co

18、lumn in series via a splitterwith a capillary analytical column. When the n-nonane hasquantitatively passed to the analytical column, the pre-columnis back-flushed to vent the higher boiling components. Theindividual components are identified by comparison withreference chromatograms and a database

19、of hydrocarbon com-pounds (see Appendix X1). The boiling point distribution up toand including n-nonane (n-C9) is calculated.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 pe

20、troleum industry. Test MethodD7169 and IP 545 purport to give such a distribution in crudeoils, but are susceptible to significant 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 tes

21、t method allows for more accurate determina-tion of the front end of the boiling point distribution curve, inaddition to 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

22、-tics given in Table 1.6.2 InletA temperature programmable vaporizing (PVT)or split/splitless inlet.6.2.1 Carrier Gas Pneumatic ControlConstant carrier gaspressure or flow control is required.6.3 ColumnA fused silica-bonded polydimethylsiloxanecoated capillary column and pre-column are employed. See

23、Table 1 for suggested columns. The analytical column shallelute hydrocarbons in a boiling point order. The eluate from theinjector passes through the pre-column before eluting onto theanalytical column.6.4 Data SystemA computer-based chromatography datasystem capable of accurately and repeatedly mea

24、suring theretention time and areas of eluting peaks. The system shall beable to acquire data at a rate adequate to accurately 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 intr

25、oduction by means ofan automatic injection is highly recommended.6.6 Flame Ionization Detector (FID), with sufficient sensi-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 dri

26、ft of not morethan 1 % per hour is obtained. The detector shall be connectedto the column so as to avoid any cold spots. 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 Configur

27、ationFor theisothermal 1 m pre-column, a heated valve box is needed withits own temperature control. The box will contain 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 becorroded by the sample (some crude oils c

28、ontain 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 detector without any coldspots. An example configuration is given in Fig. X2.1 inAppendix X2. Alternatively, a Dean Switch

29、 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 containing aTABLE 1 Typical Chromatographic ConditionsPre-column Pre-column Analytical AcceleratedA B AnalyticalColumn L

30、engthmetres 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 300 C 100 CPre-column Temperature 200 C 100 CInjector Prog. Rate C/min 50 C

31、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 time 20 min) 200 C (hold time 1 min)Flame Ionization Detector 300 C 300 CD790

32、0 18127.5 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. Reage

33、nts 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 meeting the

34、 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 an ext

35、remely 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 inter

36、nal 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 hexadec

37、ane (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 reduction

38、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 undissolved mat

39、erial.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:9.3.1 Ske

40、wnessDetermine 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 the r

41、esolution 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 = the

42、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 relative tom

43、ethane, 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 of carb

44、on, 12.011,Cn= number of carbon atoms in the hydrocarbon typegroup, of a particular carbon number,Haw= atomic mass of hydrogen, 1.008,Hn= number of hydrogen atoms in the hydrocarbon typegroup of a particular carbon number, and0.7487 = factor to normalize the result to a methane re-sponse of unity, (

45、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.FIG. 1 Calculation of Peak Skewness (see 9.3.1)D7900 18139.3.4.1 Non-Accelerated Analytical ColumnSet thesw

46、itching 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 Analytical

47、 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 Line

48、arityFor 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 linearity

49、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-flush time is opti