1、Designation: D7165 10Standard Practice forGas Chromatograph Based On-line/At-line Analysis forSulfur Content of Gaseous Fuels1This standard is issued under the fixed designation D7165; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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 practice is for the determination of volatilesulfur-containing compounds in high methane content ga
3、seousfuels such as natural gas using on-line/at-line instrumentation,and continuous fuel monitors (CFMS). It has been successfullyapplied to other types of gaseous samples including air,digester, landfill, and refinery fuel gas. The detection range forsulfur compounds, reported as picograms sulfur,
4、based uponthe analysis ofa1ccsample, is one hundred (100) to onemillion (1,000,000). This is equivalent to 0.1 to 1,000 mg/m3.1.2 This practice does not purport to measure all sulfurspecies in a sample. Only volatile compounds that are trans-ported to an instrument under the measurement conditionsse
5、lected are measured.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard1.4 This practice does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this practic
6、e to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1072 Test Method for Total Sulfur in Fuel Gases byCombustion and Barium Chloride TitrationD1945 Test Method for Analysis of Natu
7、ral Gas by GasChromatographyD3606 Test Method for Determination of Benzene andToluene in Finished Motor and Aviation Gasoline by GasChromatographyD3764 Practice for Validation of the Performance of Pro-cess Stream Analyzer SystemsD4084 Test Method for Analysis of Hydrogen Sulfide inGaseous Fuels (Le
8、ad Acetate Reaction Rate Method)D4468 Test Method for Total Sulfur in Gaseous Fuels byHydrogenolysis and Rateometric ColorimetryD4626 Practice for Calculation of Gas ChromatographicResponse FactorsD4810 Test Method for Hydrogen Sulfide in Natural GasUsing Length-of-Stain Detector TubesD5504 Test Met
9、hod for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and ChemiluminescenceD6621 Practice for Performance Testing of Process Analyz-ers for Aromatic Hydrocarbon MaterialsD6122 Practice for Validation of the Performance of Mul-tivariate Process Infrared Sp
10、ectrophotometer Based Ana-lyzer SystemsD6228 Test Method for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and Flame Photometric DetectionE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid Chromatography2.2 ISO Standard
11、s3ISO 7504 Gas Analysis-Vocabulary3. Terminology3.1 Definitions:3.1.1 calibration gas mixture, na certified gas mixturewith known composition used for the calibration of a measur-ing instrument or for the validation of a measurement or gasanalytical method.3.1.1.1 DiscussionCalibration Gas Mixtures
12、are the ana-logues of measurement standards in physical metrology (ref-erence ISO 7504 paragraph 4.1).3.1.2 direct samplingSampling where there is no directconnection between the medium to be sampled and theanalytical unit.3.1.3 in-line instrumentInstrument whose active elementis installed in the pi
13、peline and measures at pipeline conditions.1This practice is under the jurisdiction of ASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-LineAnalysis of Gaseous Fuels.Current edition approved Jan. 1, 2010. Published February 2010 Originallyappro
14、ved in 2006. Last previous edition approved in 2006 as D716506. DOI:10.1520/D7165-10.2For 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 Summary
15、page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States
16、.3.1.4 on-line instrumentAutomated instrument thatsamples gas directly from the pipeline, but is installed exter-nally.3.1.5 at-line instrumentinstrument requiring operator in-teraction to sample gas directly from the pipeline.3.1.6 continuous fuel monitor (CFM)Instrument thatsamples gas directly fr
17、om the pipeline on a continuous orsemi-continuous basis.3.1.7 total reduced sulfur (TRS)Summation of sulfurspecies where the sulfur oxidation number is 2, excludingsulfur dioxide, sulfones, and other inorganic sulfur compounds.This includes but is not limited to mercaptans, sulfides, anddisulfides.3
18、.1.8 near-real time monitoring systemsMonitoring sys-tem where measurement occurs soon after sample flow throughthe system or soon after sample extraction. The definition of anear real time monitoring system can be application specific.3.2 reference gas mixture, na certified gas mixture withknown co
19、mposition used as a reference standard from whichother compositional data are derived.3.2.1 DiscussionReference Gas Mixtures are the ana-logues of measurement standards of reference standards (ref-erence ISO 7504 paragraph 4.1.1).4. Summary of Practice4.1 A representative sample of the gaseous fuel
20、is extractedfrom a process pipe or pipeline and is transferred in a timelymanner to an analyzer inlet system. The sample is conditionedwith minimum impact on sulfur content. A precisely measuredvolume of sample is injected into the analyzer. Excess processor pipeline sample is vented or is returned
21、to the process streamdependant upon application and regulatory requirements.4.2 Sample containing carrier gas is fed to a gas chromato-graph where the components are separated using either apacked or capillary column. Measurement is performed using asuitable sulfur detection system.4.3 Calibration,
22、precision, calibration error, performanceaudit tests, maintenance methodology and miscellaneous qual-ity assurance procedures are conducted to determine analyzerperformance characteristics and validate both the operation andthe quality of generated results.5. Significance and UseOn-line, at-line, in
23、-line, CFMS, and other near-real timemonitoring systems that measure fuel gas characteristics, suchas the sulfur content, are prevalent in the natural gas and fuelgas industries. The installation and operation of particularsystems vary on the specific objectives, contractual obligations,process type
24、, regulatory requirements, and internal perfor-mance requirements needed by the user. This standard isintended to provide guidelines for standardized start-up proce-dures, operating procedures, and quality assurance practices foron-line, at-line, in-line, CFMS, and other near-real time gaschromatogr
25、aphic based sulfur monitoring systems used todetermine fuel gas sulfur content. For measurement of gaseousfuel properties using laboratory based methods the user isreferred to Test Methods D1072, D1945, D4084, D4468,D4810 and Practices D4626, E594.6. Apparatus6.1 InstrumentAny gas chromatographic ba
26、sed instru-ment of standard manufacture, with hardware necessary forinterfacing to a natural gas or other fuel gas pipeline andcontaining all features necessary for the intended application(s)can be used.6.1.1 The chromatographic parameters must be capable ofobtaining retention time repeatability of
27、 0.05 min. (3 sec.).Instrumentation must meet the performance characteristics forrepeatability and precision without encountering unacceptableinterference or bias. The components coming in contact withsample, such as tubing and valving, must be passivated orconstructed of inert materials to ensure a
28、n accurate sulfur gasmeasurement.6.2 Sample Inlet SystemA sample inlet system capable ofoperating continuously above the maximum column tempera-ture is necessary. A variety of sample inlet configurations canbe used including but not limited to on-column systems andsplit/splitless injection system ca
29、pable of splitless operationand split control from 10:1 up to 50:1. An automated gassampling valve is required for many applications. The inletsystem must be constructed of inert material and evaluatedfrequently for compatibility with reactive sulfur compounds.The sampling inlet system is heated as
30、necessary so as toprevent condensation. All wetted sampling system componentsmust be constructed of inert or passivated materials. Sampledelivered to the inlet system should be in the gas phase free ofparticulate or fluidic matter.6.2.1 Carrier and Detector Gas ControlConstant flowcontrol of carrier
31、 and detector gases is critical for optimum andconsistent analytical performance. Control is achieved by useof pressure regulators and fixed flow restrictors. The gas flowis measured by appropriate means and adjusted, as required, tothe desired value. Mass flow controllers, capable of maintain-ing a
32、 gas flow constant to within 6 1 % at the flow ratesnecessary for optimal instrument performance can be used.6.2.2 DetectorSulfur compounds can be measured using avariety of detectors including but not limited to: sulfur chemi-luminescence, flame photometric, electrochemical cell, oxida-tive cell an
33、d reductive cells. In selecting a detector, the usershould consider the linearity, sensitivity, and selectivity ofparticular detection systems prior to installation. The usershould also consider interference from substances in the gasstream that could result in inaccurate sulfur gas measurementdue t
34、o effects such as quenching.6.3 ColumnsA variety of columns can be used to separatethe sulfur compounds in the sample. Typically, a 60 m 3 0.53mm ID fused silica open tubular column containinga5mfilmthickness of bonded methyl silicone liquid phase is used. Theselected column must provide retention a
35、nd resolution charac-teristics that satisfy the intended application. The column mustbe inert towards sulfur compounds. The column must alsodemonstrate a sufficiently low liquid phase bleed at hightemperature such that a loss of the instrument response is notencountered while operating the column at
36、 elevated tempera-tures.D7165 1026.4 Data AcquisitionData acquisition and storage can beaccomplished using a number of devices and media. Followingare some examples.6.4.1 RecorderAs an example,a0to1mVrange record-ing potentiometer or equivalent, with a full-scale response timeof2sorless can be used.
37、 A 4-20 mA range recorder can alsobe used.6.4.2 IntegratorAn electronic integrating device or com-puter can be used. For GC based systems, it is suggested thatthe device and software have the following capabilities:6.4.2.1 Graphic presentation of chromatograms.6.4.2.2 Digital display of chromatograp
38、hic peak areas.6.4.2.3 Identification of peaks by retention time or relativeretention time, or both.6.4.2.4 Calculation and use of response factors.6.4.2.5 External standard calculation and data presentation.6.4.3 Distributed Control Systems (DCS)Depending onthe site requirements, the analytical res
39、ults are sometimes fedto a distributed control system. The information is then used tomake the appropriate adjustments to the process. Signal isola-tion between the analyzer and the distributed control networkis most often required. Communications protocols with theDCS will dictate the required sign
40、al output requirements forthe analyzer.6.4.4 Data Management SystemsData management sys-tems or other data and data processing repositories are some-times used to collect and process the results from a widevariety of instrumentation at a single facility. The informationis then available for rapid di
41、ssemination within the organiza-tion of the operating facility. Communications protocols withthe data management system will dictate the required signaloutput requirements for the analyzer.7. Reagents and MaterialsNOTE 1Warning: Sulfur compounds contained in permeation tubesor compressed gas cylinde
42、rs may be flammable and harmful or fatal ifingested or inhaled. Permeation tubes, which emit their contents continu-ously, and compressed gas standards should only be handled in wellventilated locations away from sparks and flames. Improper handling ofcompressed gas cylinders containing air, hydroge
43、n, argon, nitrogen orhelium can result in an explosion or in creating oxygen deficientatmospheres. Rapid release of argon, nitrogen or helium can result inasphyxiation. Compressed air supports combustion.7.1 Sulfur StandardsAccurate sulfur standards are re-quired for the quantitation of the sulfur c
44、ontent of natural gas.Permeation and compressed gas standards should be stable,and of the highest available accuracy and purity.7.1.1 Permeation DevicesSulfur standards can be pro-duced on demand using permeation tubes, one for eachselected sulfur species, gravimetrically calibrated and certifiedat
45、a convenient operating temperature. With constant tempera-ture, calibration gases covering a wide range of concentrationcan be generated by varying and accurately measuring the flowrate of diluent gas passing over the tubes. Permeation devicesdelivering calibrant at a known high purity must be used
46、sincecontaminants will adversely impact the calculation of analyteconcentration due to error in permeation rate calculated fromdifferential weight measurements of these devices. It is sug-gested that certified permeation devices be used wheneveravailable.7.1.1.1 Permeation System Temperature Control
47、Permeation devices are maintained at the calibration tempera-ture within 0.1 C.7.1.1.2 Permeation System Flow ControlThe permeationflow system measures diluent gas flow over the permeationtubes within 62 percent.7.1.1.3 Permeation tube emission rates are expressed inunits of mass of the emitted sulf
48、ur compound contained insideper unit time, i.e. nanograms of methyl mercaptan per minute.The sulfur emission rate is calculated knowing the molecularformula of the sulfur compound used in the permeation tube.7.1.1.4 Permeation tubes are inspected and weighed to thenearest 0.01 mg on at least a month
49、ly basis using a balancecalibrated against NIST traceable “S” class weights or theequivalent. Analyte concentration is calculated by weight lossand dilution gas flow rate as per Practice D3606. These devicesare discarded when the liquid contents are reduced to less thanten (10) percent of the initial volume or when the permeationsurface is unusually discolored or otherwise compromised.7.1.1.5 Permeation tubes must be stored in accordance withthe manufacturers recommendation. Improper storage canresult in damage and/or a change in the characteristics of
