1、Designation: D 7166 05Standard Practice forTotal Sulfur Analyzer Based On-line/At-line for SulfurContent of Gaseous Fuels1This standard is issued under the fixed designation D 7166; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 total sulfur fromvolatile sulfur-containing compounds in high me
3、thane orhydrogen content gaseous fuels using on-line/at-line instru-mentation.1.2 The values stated in SI units are standard. Values statedin other units are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespon
4、sibility 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:2D 1070 Test Methods for Relative Density of Gaseous FuelsD 1072 Test Method for Total Sulfur
5、in Fuel GasesD 3246 Test Method for Sulfur in Petroleum Gas by Oxi-dative MicrocoulometryD 3609 Practice for Calibration Techniques Using Perme-ation TubesD 3764 Practice for Validation of Process Stream AnalyzerSystemsD 4298 Guide for Intercomparing Permeation Tubes toEstablish TraceabilityD 4468 T
6、est Method for Total Sulfur in Gaseous Fuels byHydrogenolysis and Rateometric ColorimetryD 5287 Practice for Automatic Sampling of Gaseous FuelsD 5453 Test Method for Determination of Total Sulfur inLight Hydrocarbons, Motor Fuels and Oils by UltravioletFluorescenceD 5503 Practice for Natural Gas Sa
7、mple-Handling andConditioning Systems for Pipeline InstrumentationD 5504 Test Method for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and ChemiluminescenceD 6122 Practice for Validation of Multivariate Process In-frared SpectrophotometersD 6299 Practice
8、for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6621 Practice for Performance Testing of Process Ana-lyzers for Aromatic Hydrocarbon MaterialsD 6667 Test Method for Determination of Total VolatileSulfur in Gaseous Hydrocarbons and Liquefied
9、PetroleumGases by Ultraviolet FluorescenceD 6920 Test Method for Total Sulfur in Naphthas, Distil-lates, Reformulated Gasolines, Diesels, Biodiesels, andMotor Fuels by Oxidative Combustion and Electrochemi-cal Detection3. Terminology3.1 Definitions:3.1.1 direct samplingsampling where there is no dir
10、ectconnection between the medium to be sampled and theanalytical unit.3.1.2 in-line instrumentinstrument with an active elementinstalled in a pipeline, which is used to measure pipelinecontents or conditions.3.1.3 on-line instrumentinstrument that samples gas di-rectly from a pipeline, but is instal
11、led externally.3.1.4 at-line instrumentinstrumentation requiring opera-tor interaction that samples gas directly from the pipeline.3.1.5 continuous fuel monitorinstrument that samples gasdirectly from the pipeline on a continuous or semi-continuousbasis.3.1.6 total reduced sulfur (TRS)concentration
12、summationof all volatile sulfur species with a 2 sulfur oxidation number,excluding sulfur dioxide, sulfones and other inorganic sulfurcompounds.3.1.7 total sulfurconcentration summation of all volatilesulfur species in a sample.1This practice is under the jurisdiction of ASTM Committee D03 on Gaseou
13、sFuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-LineAnalysis of Gaseous Fuels.Current edition approved June 15, 2005. Published June 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
14、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, West Conshohocken, PA 19428-2959, United States.3.1.8 volatilemolecular characteristic wherein the sulfurspecie exists in the g
15、as phase at the operating conditions of theprocess or pipeline.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 through an appropriately designed sampling system tothe inlet of a total sulfur analyz
16、er. The sample is conditionedwith a minimum, preferably negligible, impact on the sulfurcontent. A precisely measured volume of sample is eitherinjected, or allowed to flow continuously, either directly intothe analyzer or into a carrier gas, as required by the analyzer.Some total sulfur analyzer sy
17、stems are configured such thatsample gas flows directly into the analyzer detection system.Excess process or pipeline sample is vented to atmosphere, toflare or to the process stream dependant upon application andregulatory requirements.4.2 Sample containing carrier gas is fed to a furnaceoperating
18、at an elevated temperature where sulfur compoundsare converted into detectable species. The conversion reactionmay be oxidative or reductive and may require the introductionof additional carrier or other supply gases.4.3 Furnace exit gasses are conditioned as required withrespect to temperature and
19、water content and are introducedinto the detector where quantification of the total sulfur contentoccurs.4.4 Calibration, maintenance, quality assurance and perfor-mance protocols provide a means to validate the analyzeroperation and the generated results.5. Significance and Use5.1 On-line, at-line,
20、 in-line and other near-real time moni-toring systems that measure fuel gas characteristics such as thetotal sulfur content are prevalent in the natural gas and fuel gasindustries. The installation and operation of particular systemsvary on the specific objectives, contractual obligations, processty
21、pe, regulatory requirements, and internal performance re-quirements needed by the user. This protocol is intended toprovide guidelines for standardized start-up procedures, oper-ating procedures, and quality assurance practices for on-line,at-line, in-line and other near-real time total sulfur monit
22、oringsystems.6. Apparatus6.1 InstrumentAny instrument of standard manufacture,with hardware necessary for interfacing to a natural gas,hydrogen or other fuel gas pipeline and containing all thefeatures necessary for the intended application(s) can be used.6.1.1 Specific Sulfur Specie Detection Syste
23、msThe oper-ating parameters employed generally must be capable ofconverting all of the volatile sulfur species in the sample intoa single detectable species such as sulfur dioxide or hydrogensulfide. Instrumentation must satisfy or exceed other analyticperformance characteristics for accuracy and pr
24、ecision for theintended application without encountering unacceptable inter-ference or bias. In addition, components in contact with samplestreams such as tubing and valving must be constructed ofsuitable inert, or passivated, materials to ensure constituents inthe fuel stream do not degrade these c
25、omponents or alter thecomposition of the sampled gas.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 components should be selected basedupon sound analyti
26、c and engineering considerations. Samplingpractices for gaseous fuels can be found in Practice D 5287.6.3 Sample Inlet System The siting and installation of anat-line or on-line monitor is critical for collecting representa-tive information on sulfur content. Factors that should beconsidered in siti
27、ng an instrument include ease of calibration,ease of access for repair or maintenance, sample uniformity atthe sampling point, appropriateness of samples from a sam-pling location, ambient conditions, and of course safety issues.An automated gas sampling valve is required in many appli-cations. All
28、sampling system components in contact with thefuel stream must be constructed of inert or passivated materi-als. Care should be taken to ensure that the extracted sample ismaintained as a particulate and condensate free gas. Heating atthe point of pressure reduction or along the sample line to thean
29、alyzer and the use of a filter may be required to ensure thatthe sample is maintained in the gas phase. The need for heattracing and the extent to which it is required will be site andapplication specific. In general, considerations impacting heattracing decisions include sample compositions and the
30、 ex-pected variations, ambient temperature fluctuations, operatingpressures, anticipated pressure differentials in sample systemcomponents, and safety considerations. Sample filtrationshould be utilized as required to remove particulate matterfrom the extracted sample. The sampling frequency relativ
31、e tothe process bandwidth is critical to ensuring that the reportedanalytical results adequately represent the process being moni-tored. The Nyquist-Shannon sampling criterion of a samplingfrequency that exceeds twice the process bandwidth can beused to establish a minimum analytical cycle time. Sam
32、plehandling and conditioning system practices can be found inPractice D 5503.6.3.1 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 restrict
33、ors as well asrotameters. Temperature control is generally vital for ensuringconsistent operation of these devices. The gas flow is measuredby appropriate means and adjusted as necessary. Mass flowcontrollers, capable of maintaining a gas flow constant towithin 61 % at the flow rates necessary for o
34、ptimal instrumentperformance are typically used.6.3.2 DetectorsCommon detectors used for total sulfurdeterminations include chemiluminescence (Test MethodD 5504), microcoulometry (Test Method D 3246), electro-chemical (Test Method D 6920), lead acetate (Test MethodD 4468), titration, such as barium
35、chloride (Test MethodD 1072), ultra-violet fluorescence (Test Methods D 5453 andD 6667), both continuous and pulsed. Other detectors can beused provided they have appropriate linearity, sensitivity, andselectivity for the selected application. In selecting a detector,D7166052the user should consider
36、 the linearity, sensitivity, and selectiv-ity of particular 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.6.4 Data AcquisitionData acquisition a
37、nd storage can beaccomplished using a number of devices and media. Followingare some examples.6.4.1 RecorderA 0 to 1 mV range recording potentiom-eter or equivalent can be used.6.4.2 CommunicationsEfficient communications betweenthe analyzer and the host depend on resolving any and allinterface issu
38、es. Signals to and from the host are typicallyoptically isolated 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 standa
39、rds, air,nitrogen, hydrogen, argon or helium can result in explosion. Rapid releaseof nitrogen or helium can result in asphyxiation. Compressed air supportscombustion. Sulfur species and radiation sources can be toxic.7.1 StandardsAccurate sulfur standards are required forthe determination of total
40、sulfur. Standards are available asprepared standards in the form of a compressed gas or as apreparable standard in the form of a permeation tube calibra-tion device.7.2 Prepared StandardsCompressed gas standards shouldbe stable, of the highest available accuracy and purity and usedin accordance with
41、 the manufacturers recommendations. Thematrix components in the reference standard can be represen-tative of the monitored gas. Alternatively, a simplified matrixcan be used if the analyzer can be calibrated in accordance withthe manufacturers specifications. Sulfur concentrations aredependent on th
42、e detector linearity and are typically selectedbetween one half and twice their expected concentration in themonitored gas. Alternatively, a critical value of sulfur concen-tration , such as an alarm limit, can be used to identlify thedesired total sulfur concentration of the standard. Using asulfur
43、 specie that differs from what the detector sees allows fora total analyzer system performance check. Standards must bemaintained within the temperature range specified by themanufacturer to ensure accuracy and stability.7.3 Permeation DevicesPermeation devices contain analiquot of a specific compou
44、nd that continuously diffuses at adetermined rate through a permeable medium. A dry inertcarrier gas flows at a constant rate across the medium at aconstant temperature consistent with the manufacturers rec-ommendations to create a calibration gas that then flows to theanalyzer. Proper storage, in a
45、ccordance with the manufactur-ers recommendations, is required to prevent damage to themembrane. A sufficiently long equilibration time is requiredwhen the permeation device temperature is changed to ensurethe reestablishment of a constant permeation rate. Calibrationdevices using permeation tubes c
46、ontain a temperature con-trolled oven and employ flow control to maintain a constantdiluent flow rate. Practice D 3609 and Guide D 4298 containadditional information on permeation tubes.8. Equipment Siting and Installation8.1 Asample inlet system capable of operating continuouslyand delivering a gas
47、 phase sample to the analyzer is necessary.The location of the sample inlet to the analyzer relative to thesample extraction point is critical to obtaining timely analyticalresults. Ideally, the analyzer is close coupled to the sampleextraction point and there is an insignificant sampling lag time.N
48、ormally, the analyzer is mounted at some distance away fromthe sample extraction point. This increased distance representsincreased lag time between when a sample is extracted from aprocess and when an analytical result is reported. The maxi-mum allowable lag time depends on the specifics of thesamp
49、ling location relative to the process being sampled. A fastloop sweep can be used to minimize the lag time by creating abypass loop that flows sample from the process to the analyzerand is then returned to the process or is vented.8.2 The sample should flow continuously without impedi-ment through the instrument sampling system. The samplingsystem should be capable of delivering a sample to thedetection system in 10 minutes or less.8.3 A monitoring system pretest of both sampling andanalysis functions is critical to determining monitoring systemcharacteristics,
