1、Designation: D 7165 06Standard Practice forGas Chromatograph Based On-line/At-line Analysis forSulfur Content of Gaseous Fuels1This standard is issued under the fixed designation D 7165; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 gaseousfuels 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 sulfu
4、r, 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 condition
5、sselected are measured.1.3 The values stated in SI units are standard. The valuesstated in inch-pound units are for information only.1.4 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 practice to estab
6、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1072 Test Method for Total Sulfur in Fuel GasesD 1945 Test Method for Analysis of Natural Gas by GasChromatographyD 3606 Test Method for
7、Determination of Benzene andToluene in Finished Motor and Aviation Gasoline by GasChromatographyD 4084 Test Method for Analysis of Hydrogen Sulfide inGaseous Fuels (Lead Acetate Reaction Rate Method)D 4468 Test Method for Total Sulfur in Gaseous Fuels byHydrogenolysis and Rateometric ColorimetryD 46
8、26 Practice for Calculation of Gas ChromatographicResponse FactorsD 4810 Test Method for Hydrogen Sulfide in Natural GasUsing Length-of-Stain Detector TubesD 5504 Test Method for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and ChemiluminescenceD 6228 Te
9、st Method for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and Flame Photometric DetectionE 594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid Chromatography3. Terminology3.1 Definitions:3.1.1 direct samplingSampling wh
10、ere there is no directconnection between the medium to be sampled and theanalytical unit.3.1.2 in-line instrumentInstrument whose active elementis installed in the pipeline and measures at pipeline conditions.3.1.3 on-line instrumentAutomated instrument thatsamples gas directly from the pipeline, bu
11、t is installed exter-nally.3.1.4 at-line instrumentinstrument requiring operator in-teraction to sample gas directly from the pipeline.3.1.5 continuous fuel monitor (CFM)Instrument thatsamples gas directly from the pipeline on a continuous orsemi-continuous basis.3.1.6 total reduced sulfur (TRS)Summ
12、ation 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.3.1.7 near-real time monitoring systemsMonitoring sys-tem where measurement occurs soon after
13、 sample flow throughthe system or soon after sample extraction. The definition of anear real time monitoring system can be application specific.4. Summary of Practice4.1 A representative sample of the gaseous fuel is extractedfrom a process pipe or pipeline and is transferred in a timelymanner to an
14、 analyzer inlet system. The sample is conditioned1This 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. 15, 2006. Published January 2006.2For refe
15、renced 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
16、t Conshohocken, PA 19428-2959, United States.with minimum impact on sulfur content. A precisely measuredvolume of sample is injected into the analyzer. Excess processor pipeline sample is vented or is returned to the process streamdependant upon application and regulatory requirements.4.2 Sample con
17、taining 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, precision, calibration error, performanceaudit tests, maintenance methodology and miscella
18、neous 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-line, CFMS, and other near-real timemonitoring systems that measure fuel gas characterist
19、ics, 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, regulatory requirements, and internal perfor-mance requirements needed by the user. This
20、 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 gaschromatographic based sulfur monitoring systems used todetermine fuel gas sulfur content. For measur
21、ement of gaseousfuel properties using laboratory based methods the user isreferred to Test Methods D 1072, D 1945, D 4084, D 4468,D 4810 and Practices D 4626, E 594.6. Apparatus6.1 InstrumentAny gas chromatographic based instru-ment of standard manufacture, with hardware necessary forinterfacing to
22、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 0.05 min. (3 sec.).Instrumentation must meet the performance characteristics forre
23、peatability 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 an accurate sulfur gasmeasurement.6.2 Sample Inlet SystemA sample inlet system capab
24、le 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 capable of splitless operationand split control from 10:1 up to 50:1. An automated ga
25、ssampling 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 necessary so as toprevent condensation. All wetted sampling system componentsmust b
26、e 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 and detector gases is critical for optimum andconsistent analytical performance. C
27、ontrol 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 gas flow constant to within 6 1 % at the flow ratesnecessary for optimal instrumen
28、t 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 and reductive cells. In selecting a detector, the usershould consider the linearity,
29、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 to effects such as quenching.6.3 ColumnsA variety of columns can be used to separate
30、the 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 and resolution charac-teristics that satisfy the intended application. The column mu
31、stbe 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 elevated tempera-tures.6.4 Data AcquisitionData acquisition and storage can beacco
32、mplished 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. A 4-20 mA range recorder can alsobe used.6.4.2 IntegratorAn electronic integrating device o
33、r 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 chromatographic peak areas.6.4.2.3 Identification of peaks by retention time or relativeretention time,
34、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 results are sometimes fedto a distributed control system. The information is then used tomake t
35、he 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 signal output requirements forthe analyzer.6.4.4 Data Management SystemsData management sys-tems
36、 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 dissemination within the organiza-tion of the operating facility. Communications protocols wit
37、hD7165062the 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 cylinders may be flammable and harmful or fatal ifingested or inhaled. Permeation tubes, wh
38、ich 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, hydrogen, argon, nitrogen orhelium can result in an explosion or in creating oxygen deficie
39、ntatmospheres. 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 content of natural gas.Permeation and compressed gas standards should be stable,and o
40、f 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 a convenient operating temperature. With constant tempera-ture, calibration gases co
41、vering 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 sincecontaminants will adversely impact the calculation of analyteconcentration due
42、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 ControlPermeation devices are maintained at the calibration tempera-ture within 0.1 C.7.1.1
43、.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 sulfur compound contained insideper unit time, i.e. nanograms of methyl mercaptan per mi
44、nute.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 monthly basis using a balancecalibrated against NIST traceable “S” class weights or theeq
45、uivalent. Analyte concentration is calculated by weight lossand dilution gas flow rate as per Practice D 3609. Thesedevices are discarded when the liquid contents are reduced toless than ten (10) percent of the initial volume or when thepermeation surface is unusually discolored or otherwise com-pro
46、mised.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 thepermeation membrane. Such damage and/or characteristicchange results in an actual permeation rate that differs from thec
47、ertified permeation rate.7.2 Compressed Gas StandardsAlternatively, blendedgaseous sulfur standards in nitrogen, helium or methane basegas may be used. Care must be exercised in the use ofcompressed gas standards since they can introduce errors inmeasurement due to lack of uniformity in their manufa
48、cture orinstability in their storage and use. Standards should beblended such that components will not condense under storageor while the standard is in use. The protocol for compressed gasstandards contained in the appendix can be used to ensureuniformity in compressed gas standard manufacture and
49、pro-vide for traceability to a NIST or NMi (Nederlands Meetinsti-tuut) reference material.7.2.1 Compressed gas standard regulators must be appro-priate for the delivery of sulfur gases and attached fittings mustbe passivated or inert to sulfur gases.7.2.2 All compressed gas standards must be re-certified asrecommended by the manufacturer or as needed to insureaccuracy.7.3 The following sulfur compounds, including the molecu-lar formula and the CAS number, are commonly found or areadded to natural gas and related fuel gases and may be usefulas calibrants for on
