1、Designation: D7164 10 (Reapproved 2015)Standard Practice forOn-line/At-line Heating Value Determination of GaseousFuels by Gas Chromatography1This standard is issued under the fixed designation D7164; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 practice is for the determination of heating value inhigh methane content gaseous f
3、uels such as natural gas usingan on-line/at-line gas chromatograph.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
4、is theresponsibility of the user of this standard 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:2D1070 Test Methods for Relative Density of Gaseous FuelsD1945 Test Method for Ana
5、lysis of Natural Gas by GasChromatographyD1946 Practice for Analysis of Reformed Gas by GasChromatographyD3588 Practice for Calculating Heat Value, CompressibilityFactor, and Relative Density of Gaseous FuelsD3764 Practice for Validation of the Performance of ProcessStream Analyzer SystemsD4626 Prac
6、tice for Calculation of Gas ChromatographicResponse FactorsD5287 Practice for Automatic Sampling of Gaseous FuelsD5503 Practice for Natural Gas Sample-Handling and Con-ditioning Systems for Pipeline InstrumentationD6122 Practice for Validation of the Performance of Multi-variate Online, At-Line, and
7、 Laboratory Infrared Spectro-photometer Based Analyzer SystemsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6621 Practice for Performance Testing of Process Analyz-ers for Aromatic Hydrocarbon MaterialsE2
8、60 Practice for Packed Column Gas ChromatographyE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 ISO Standards3ISO 7504 Gas Analysis-Vocabulary3. Term
9、inology3.1 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 are the ana-logues of measurement standar
10、ds 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 with an active elementinstalled in a pipeline, which is used to measure pipelinecon
11、tents or conditions.3.1.4 on-line instrumentinstrument that samples gas di-rectly from a pipeline, but is installed externally.3.1.5 at-line instrumentinstrumentation requiring operatorinteraction that samples gas directly from the pipeline.3.1.6 continuous fuel monitorinstrument that samples gasdir
12、ectly from the pipeline on a continuous or semi-continuousbasis.3.1.7 heating valuein general terms, the heating value isthe total energy per volume transferred as heat from the1This practice is under the jurisdiction of ASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommi
13、ttee D03.12 on On-Line/At-LineAnalysis of Gaseous Fuels.Current edition approved Nov. 1, 2015. Published December 2015. Originallyapproved in 2005. Last previous edition approved in 2010 as D716410. DOI:10.1520/D7164-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
14、ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerla
15、nd, http:/www.iso.ch.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1complete, ideal combustion of the gas at a specified tempera-ture and pressure. The heating value can be reported on a netor gross basis for a gaseous stream that is
16、 assumed to be fullywater vapor saturated.3.1.8 gross heating value(also called higher heatingvalue)the amount of energy per volume transferred as heatfrom the complete, ideal combustion of the gas at standardtemperature in which all the water formed by the reactioncondenses to liquid.3.1.9 net heat
17、ing value(also called lower heating value)the amount of energy per volume transferred as heat from thecomplete, ideal combustion of the gas at standard temperaturein which all the water formed by the reaction remains in thevapor state.3.2 reference gas mixture, na certified gas mixture withknown com
18、position 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 Arepresentative sample of the Gaseous Fuel is
19、 extractedfrom a process pipe or a pipeline and is transferred in a timelymanner to an analyzer sampling system. After appropriateconditioning steps that maintain the sample integrity arecompleted, a precise volume of sample is injected onto anappropriate gas chromatographic column. Excess extracted
20、process or pipeline sample is vented to atmosphere, a flareheader, or is returned to the process in accordance withapplicable economic and environmental requirements andregulations.4.2 Sample constituents are separated in the column to eluteindividually for identification and quantification by the d
21、etectorand its data handling system. The heating value is calculatedusing the results of the compositional analysis using anappropriate algorithm.4.3 Calibration, maintenance, and performance protocolsprovide a means to validate the analyzer operation.5. Significance and Use5.1 On-line, at-line, in-
22、line and other near-real time moni-toring systems that measure fuel gas characteristics such as theheating value are prevalent in the natural gas and fuel gasindustries. The installation and operation of particular systemsvary on the specific objectives, process type, regulatoryrequirements, and int
23、ernal performance requirements neededby the user. This protocol is intended to provide guidelines forstandardized start-up procedures, operating procedures, andquality assurance practices for on-line, at-line, in-line and othernear-real time heating value monitoring systems.6. Apparatus6.1 Instrumen
24、tAny instrument of standard manufacture,with hardware necessary for interfacing to a natural gas orother fuel gas pipeline and containing all the features necessaryfor the intended application(s) can be used.6.1.1 Chromatographic-based SystemsThe chromato-graphic parameters employed generally should
25、 be capable ofobtaining a relative retention time repeatability of 0.05 min (3s) for duplicate measurements. Instrumentation should satisfyor exceed other chromatographic and analytic performancecharacteristics for accuracy and precision for the intendedapplication without encountering unacceptable
26、interference orbias. In addition, components in contact with sample streamssuch as tubing and valving must be constructed of suitable inertmaterials to ensure constituents in the fuel stream do notdegrade these components or alter the composition of thesampled gas. Additional information related to
27、analyzinggaseous fuels using gas chromatography can be found in TestMethod D1945 and Practice D1946.6.2 Sample Probes/Sample ExtractionThe location andorientation of sampling components are critical for ensuringthat a representative sample is analyzed. The locations andorientation of sampling compon
28、ents should be selected basedupon sound analytic and engineering considerations. Samplingpractices for gaseous fuels can be found in Practice D5287.6.3 Sample Inlet SystemThe siting and installation of anat-line or on-line monitor is critical for collecting representa-tive information on heating val
29、ue content. Factors that shouldbe considered in siting an instrument include ease ofcalibration, ease of access for repair or maintenance, sampleuniformity at the sampling point, appropriateness of samplesfrom a sampling location, ambient conditions, and of coursesafety issues. An automated gas samp
30、ling valve is required inmany applications.All sampling system components in contactwith the fuel stream must be constructed of inert or passivatedmaterials. Care should be taken to ensure that the extractedsample is maintained in a single clean gaseous phase. Theaddition of heat at the point of pre
31、ssure reduction or along thesample line to the analyzer may be required to ensure that thesample is maintained in the gas phase. The need for heattracing and the extent to which it is required will be sitespecific. In general, considerations impacting heat tracingdecisions include sample composition
32、s and the expectedvariations, ambient temperature fluctuations, operatingpressures, and anticipated pressure differentials in samplesystem components. Sample filtration should be utilized asrequired to remove particulate matter from the extractedsample. The sampling frequency relative to the process
33、 band-width is critical to ensuring that the reported analytical resultsadequately represent the process being monitored. TheNyquist-Shannon sampling criterion of a sampling frequencythat exceeds twice the process bandwidth can be used toestablish a minimum analytical cycle time. Sample handlingand
34、conditioning system practices can be found in PracticeD5503.6.3.1 Carrier and Detector Gas ControlConstant flowcontrol of carrier and detector gases is critical for optimum andconsistent analytical performance. Control is achieved by useof pressure regulators and fixed flow restrictors. Temperaturec
35、ontrol is generally vital for ensuring consistent operation ofthese devices. The gas flow is measured by appropriate meansand adjusted as necessary. Mass flow controllers, capable ofD7164 10 (2015)2maintaining gas flow constant to 61 % at the flow ratesnecessary for optimal instrument performance ar
36、e generallyused.6.3.2 DetectorsA thermal conductivity detector (TCD) iscommonly used. Other detectors, such as the flame ionizationdetector (FID), Practice E594, can be used but should at leastmeet TCD linearity, sensitivity, and selectivity in the selectedapplication.6.4 ColumnsA variety of columns
37、, ranging from packedcolumns to open tubular capillary columns, can be used in thedetermination of the Heating Value of a gaseous fuel. Packedcolumns and open tubular capillary columns are covered inPractices E260 and E1510 respectively. Columns should beconditioned in accordance with the manufactur
38、ers recommen-dations. The selected column must provide retention andresolution characteristics that satisfy the intended application.The column must be inert towards gaseous fuel components. Ifthe selected column utilizes a liquid phase, bleeding at hightemperatures must be sufficiently low so as to
39、 avoid the loss ofinstrument response during high temperature operation.6.5 Data AcquisitionData acquisition and storage can beaccomplished using a number of devices and media. Followingare some examples.6.5.1 RecorderA0 to 1 mV range recording potentiometeror equivalent, with a full-scale response
40、time of2sorless canbe used.6.5.2 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:6.5.2.1 Graphic presentation of chromatograms.6.5.2.2 Digital display of chromatographic peak areas.
41、6.5.2.3 Identification of peaks by retention time or relativeretention time, or both.6.5.2.4 Calculation and use of response factors.6.5.2.5 External standard calculation and data presentation.6.5.2.6 Site-appropriate archives up to one month of allruns. Archives could include raw data, derived comp
42、onentvalues or heating value results or both. Hourly, daily, andmonthly averages are included as required.6.5.3 Communications SystemsEfficient communicationsbetween the analyzer and the host depend on resolving any andall interface issues. Signals to and from the host are typicallyoptically isolate
43、d from each other.7. Reagents and MaterialsNOTE 1Warning: Compressed gas standards should only be handledin well ventilated locations away from sparks and flames. Improperhandling of compressed gas cylinders containing calibration standards, air,nitrogen, hydrogen, argon or helium can result in expl
44、osion. Rapid releaseof nitrogen or helium can result in asphyxiation. Compressed air supportscombustion.7.1 StandardsThe components in the reference standardshould be representative of the monitored gas. Concentrationsof major components are typically selected between one halfand twice their expecte
45、d concentration in the monitored gas.Standards must be maintained as close as practicable to aconstant temperature within the temperature range specified bythe manufacturer to ensure accuracy and stability.8. Equipment Siting and Installation8.1 Asample inlet system capable of operating continuously
46、at or above the maximum column operating temperature isnecessary. The location of the sample inlet to the analyzerrelative to the sample extraction point is critical to obtainingtimely analytical results. Ideally, the analyzer is close coupledto the sample extraction point and there is an insignific
47、antsampling lag time. Normally, the analyzer is mounted at somedistance away from the sample extraction point. This increaseddistance represents increased lag time between when a sampleis extracted from a process and when an analytical result isreported. The maximum allowable lag time depends on the
48、specifics of the sampling location relative to the process beingsampled. A fast loop sweep can be used to minimize the lagtime by creating a bypass loop that flows sample from theprocess to the analyzer and is then returned to the process or isvented.8.2 The sample should flow continuously without i
49、mpedi-ment through the instrument sampling system. The samplingsystem should be capable of delivering a sample to thedetection system within the cycle time of the analyzer. Shortertimes may be required to meet the intended need.8.3 A monitoring system pretest of both sampling andanalysis functions is critical to determining monitoring systemcharacteristics, identify unforeseen factors affecting measure-ment and to determine optimal operating conditions for theintended use. This pretest is performed before the system isplaced in continuous service and may
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