1、Designation: D7833 12D7833 14Standard Test Method forDetermination of Hydrocarbons and Non-HydrocarbonGases in Gaseous Mixtures by Gas Chromatography1This standard is issued under the fixed designation D7833; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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 is intended to quantitatively determine the non-condensed hydro
3、carbon gases with carbon numbers fromC1 to C5+ and non-hydrocarbon gases, such as H2, CO2, O2, N2, and CO, in gaseous samples. This test method is a companionstandard test method to Test Method D1945 and Practice D1946 differing in that it incorporates use of capillary columns insteadof packed colum
4、ns and allows other technological differences.1.2 Hydrogen sulfide can be detected but may not be accurately determined by this procedure due to loss in sample containersor sample lines and possible reactions unless special precautions are taken.1.3 Non-hydrocarbon gases have a lower detection limit
5、 in the concentration range of 0.03 to 100 mole percent using a thermalconductivity detector (TCD) and C1 to C6 hydrocarbons have a lower detection limit in the range of 0.005 to 100 mole percentusing a flame ionization detector (FID); using a TCD may increase the lower detection limit to approximat
6、ely 0.03 mole percent.1.3.1 Hydrocarbon detection limits can be reduced with the use of pre-concentration techniques and/or cryogenic trapping.1.4 This test method does not fully determine individual hydrocarbons heavier than benzene, which are grouped together as C7+When detailed analysis is not re
7、quired the compounds with carbon number greater than C5 may be grouped as either C6+, or C7+.Accurate analysis of C5+ components depends on proper vaporization of these compounds during sampling at process unit sourcesas well as in the sample introduction into the analyzer in the laboratory.1.5 Wate
8、r vapor may interfere with the C6+ analysis if a TCD detector is used.1.6 Helium and argon may interfere with the determination of hydrogen and oxygen respectively. Depending on the analyzerused, pentenes, if present, may either be separated or grouped with the C6+ components.1.7 The values stated i
9、n SI units are to be regarded as standard. No other units of measurement are included in this standard.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and h
10、ealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1945 Test Method for Analysis of Natural Gas by Gas ChromatographyD1946 Practice for Analysis of Reformed Gas by Gas ChromatographyD3588 Practice for Calculating Heat Val
11、ue, Compressibility Factor, and Relative Density of Gaseous FuelsE355 Practice for Gas Chromatography Terms and RelationshipsE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas ChromatographsF307 Practice for Sampling Pressurized Gas for Gas Analysis2.2 ASTM Publication:
12、ASTM DS 4B, 1991 Physical Constants of Hydrocarbon and Non-Hydrocarbon Compounds1 This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.07 on Analysis of ChemicalComposition of Gaseous Fuels.Current edition approved Nov
13、. 1, 2012June 1, 2014. Published December 2012June 2014. Originally approved in 2012. Last previous edition approved in 2012 asD7833-12. DOI: 10.1520/D7833-12.10.1520/D7833-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For
14、 Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard 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 no
15、t be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor D
16、rive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Terminology related to the practice of gas chromatography can be found in Practice E355.3.2 Definitions:3.2.1 sample seta collection of samples taken from the same source or at similar component composition and conc
17、entrations.4. Summary of Test Method4.1 Components in a representative sample are physically separated by gas chromatography (GC) and compared to calibrationdata obtained under identical operating conditions from a reference standard mixture of known composition. The numerousheavy-end components of
18、a sample can be grouped into irregular peaks by reversing the direction of the carrier gas through thecolumn at such time as to group the heavy ends either as C5 and heavier, C6 and heavier, or C7 and heavier or alternatively elutethem in the non-backflushed mode and summed accordingly. The composit
19、ion of the sample is calculated by comparing the peakareas with the corresponding values obtained with the reference standard.5. Significance and Use5.1 The hydrocarbon component distribution of gaseous mixtures is often required for end-use sale of this material.Applicationssuch as chemical feedsto
20、ck or fuel require precise compositional data to ensure uniform quality. Trace amounts of somehydrocarbon impurities in these materials can have adverse effects on their use and processing. Certain regulations may requireuse of such method.5.2 The component distribution data of gaseous mixtures can
21、be used to calculate physical properties such as relative density,vapor pressure, and heating value calculations found in Practice D3588. Precision and accuracy of compositional data is extremelyimportant when this data is used to calculate various properties of petroleum products.6. Apparatus6.1 Ga
22、s Chromatograph (GC)This method allows the use of most gas chromatographic analyzers designed for gas analysis.Generally, any gas chromatographic instrument with a linear temperature programmable column oven or adequate temperaturecontrol to provide the required separation of gaseous compounds being
23、 analyzed may be used. The temperature control must becapable of obtaining retention time repeatability within 5% of the retention time for each component throughout the scope of thisanalysis for hydrocarbon and non-hydrocarbon gas analyses.6.1.1 DetectorThe type and number of detectors employed is
24、dependent on gas analyzer model and vendor used. Detectorsthat can be used include, but are not limited to FID, TCD, AED (Atomic Emission Detector), HID (Helium Ionization Detector),and MS(Mass Spectrometer). Many systems use a 3 detector system:(1) One FID (Flame Ionization Detector) for the determ
25、ination of the hydrocarbon gases for the compounds listed in Table 1,(2) One TCD (Thermal Conductivity Detector) dedicated to the determination of hydrogen utilizing nitrogen or argon as acarrier gas, andTABLE 1 List of Components Typically Analyzed (Hydrocarbons)Component FID TCDC5 olefin / C6+ com
26、posite X Xoxygen/argon composite Xhydrogen Xcarbon dioxide Xhydrogen sulfide Xnitrogen Xcarbon monoxide Xmethane X Xethane X Xethylene X Xpropane X Xpropylene X Xacetylene X Xisobutane X Xpropadiene X Xn-butane X Xtrans-2-butene X X1-butene X Xisobutylene X Xcis-2-butene X Xneopentane X Xcyclopentan
27、e X Xisopentane X Xmethyl acetylene X Xn-pentane X X1,3-butadiene X XD7833 142(3) One TCD for the determination of all other required non-hydrocarbon gases using helium as the carrier gas.6.1.2 ATCD may also be used for the analysis of the hydrocarbon gases (replacing the FID) when high sensitivity
28、(5 vol%.NOTE 1When helium is not expected to be present in samples the resolution of hydrogen from helium is not critical.6.5 Non-Hydrocarbon and Light Hydrocarbon Gas Analysis (Except Hydrogen) (Thermal Conductivity Detector)A 10-portgas sampling valve in combination with a 6-port switching valve o
29、r equivalent is used with helium or hydrogen carrier to analyzefor CO2, O2, N2, CH4, C2H6, and CO and in some cases H2S.Any column or multiple columns may be used as long as the desiredcomponents are well separated. ATCD may also be used for the analysis of the hydrocarbon gases (replacing the FID)
30、when highsensitivity (5 vol%.6.6 Hydrocarbon Gas Analysis (Flame Ionization Detector)A 6-port gas-sampling valve in combination with a 6-portpre-column switching valve (backflush) for the C6+ or C7+ hydrocarbons is typically used. These valves shall be contained in aheated enclosure and operated at
31、a sufficiently high temperature, and within the limits of the valve operating temperature asspecified by manufacturer, to prevent condensation of the C6+ components in the sample. The use of a frit or packed-screen typefilter ahead of the sample introduction port is recommended with use of PLOT colu
32、mns. The gas-sampling valve shall provide arepeatability of at least 6 2% relative to the sample volume introduction for major compounds present at 5 vol%.6.7 Column Series/Reversal Switching ValveIf desired, a multi-port valve may be used to provide the C5 olefin/C6+ or C7+determination for this an
33、alysis. Other switching valve configurations may be used to allow the elution of the gaseous compounds.Consult instrument manufacturer for optimum configuration.NOTE 2If a dimethylsilicone capillary column or equivalent is used for the hydrocarbon analysis, then the capillary column may be used in t
34、heforeflush mode (no-backflush) until all of the hydrocarbons have eluted using temperature programming or equivalent.FIG. 2 Example Chromatogram of Non-Hydrocarbon and Light Hydrocarbon Gases from System Configuration in Fig. 1D7833 1446.8 Gas ControlsThe gas chromatograph shall be provided with su
35、itable facilities for delivery and control of carrier gases anddetector gases. This will consist of the appropriate gas supply, down-stream regulators, and supply tubing as well as the mass orpressure controls for the precise regulation of the instrument operation.NOTE 3Most gas chromatograph suppli
36、ers will provide these devices or recommend the proper suppliers. Ensure that the analyzer when heated andin-use does not run out of carrier gases. In addition, running out of carrier gas will require flushing out any air introduced into the sample inlet system,column and/or detector.6.9 ColumnsCond
37、ition all columns used according to the manufacturers suggestions prior to putting the system in service.6.10 Analytical Column for Hydrocarbon AnalysisA recommended analytical column for the hydrocarbon analysis in Fig. 1is a 50 m 0.53 mm (I.D.) deactivated alumina (Al2O3) porous layer open tubular
38、 (PLOT) column used with a FID detector forlowest detection limits. Relative retention order for the alumina PLOT column is dependent upon the deactivation method for thecolumn and moisture content. WarningSpecifically test the alumina PLOT column to ensure that the column does not adsorbpropadiene,
39、 methyl acetylene, and butadiene when such compounds need to be determined. This condition can exist dependingupon the degree of column deactivation.6.10.1 Routine re-conditioning of the alumina PLOT column may be required to maintain column performance. It isrecommended that a standby method be use
40、d when the system is idle to maintain the PLOT column at a temperature of at least130C or as recommended by the manufacturer.6.10.2 Alternatively, any column or combination of columns that provides the appropriate component C1-C5 separations maybe used.6.11 Pre-column for Hydrocarbon Gas AnalysisWhe
41、n using the alumina PLOT column, if an initial backflush of the C5+/C6+components through the use of the sequence reversal/backflush valve is desired, a second column is required.Any pre-column thatprovides separation between the components of interest and the composite heavier components may be use
42、d. Choices may includelengths of column such as a 10 to 30 m section of 0.53 mm (I.D.) 3-m film thickness dimethyl polysiloxane or a 9 to 15 cm sectionof the same column material as the analytical column or any pre-column that provides the desired retention of pentenes, hexanes,and heavier component
43、s. This pre-column acts to keep the heavier components away from the analytical alumina PLOT columnNOTE 1For the hydrocarbon analysis, the Al2O3 PLOT was used.FIG. 3 Example Chromatogram of Hydrocarbons from System Configuration in Fig. 1D7833 145and to backflush the heavier components as a composit
44、e peak to the detector for quantification. If analysis of individual C6-C7components is required, extend the backflush valve time until the desired components have eluted and prior to backflushing theremaining heavier compounds.6.12 Analytical Columns for Hydrogen AnalysisGenerally hydrogen analysis
45、 consists of a pre-column to remove most of thehydrocarbons, H2S and CO2 and a Molecular Sieve 5Aor equivalent for separation of hydrogen from oxygen and nitrogen. Followvendors recommendations.6.13 Analytical Columns for Other Non-Hydrocarbon GasesGenerally a series-bypass two-valve configuration i
46、s used,consisting of porous polymer-molecular sieve 5A or 13X combination. Follow vendors recommendations.7. Reagents and Materials7.1 All chemicals are reagent grade unless specified otherwise, and all water used is distilled or deionized. WarningHydrogensulfide contained in calibration standards m
47、ay be flammable and harmful or fatal if ingested or inhaled. Calibration standards orsamples containing hydrogen sulfide should be handled in well ventilated locations away from sparks and flames.7.2 Carrier GasesFor carrier gases, it is strongly recommended to install commercial active oxygen scrub
48、bers and waterdryers, such as molecular sieves, ahead of the instrument to protect the chromatographic columns. Follow supplier instructions inthe use of such gas purifiers and replace as necessary.7.2.1 Chromatographic Grade Hydrogen, 99.995% minimum purity, 5 vol%. Failure to compare may result fr
49、om lack of injection splitter (if used) linearity or use of a standard that hasnot been maintained according to the standard manufacturers recommendations. It is necessary to compare calculated results tothe certified values for a known standard before accepting the calibration.10. Sampling10.1 Sampling at the sample source, the use of appropriate sample containers that are stored and transported properly, andintroduction into a chromatograph must be done in a manner that ensures that a representative sample is being analyzed. SeePractice F307 for the
