1、Designation: D7551 10 (Reapproved 2015)Standard Test Method forDetermination of Total Volatile Sulfur in GaseousHydrocarbons and Liquefied Petroleum Gases and NaturalGas by Ultraviolet Fluorescence1This standard is issued under the fixed designation D7551; the number immediately following the design
2、ation indicates the year oforiginal adoption or, 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 covers the dete
3、rmination of totalvolatile sulfur in gaseous hydrocarbons, Liquefied PetroleumGases (LPG) and Liquefied Natural Gas (LNG). It is applicableto analysis of natural gaseous fuels, process intermediates, finalproduct hydrocarbons and generic gaseous fuels containingsulfur in the range of 1 to 200 mg/kg.
4、 Samples can also betested at other total sulfur levels using either pre-concentrationmethods or sample dilution using a diluent gas. The method-ology for preconcentration and dilution techniques is notcovered in this test method. The precision statement does notapply if these techniques are used in
5、 conjunction with this testmethod. The diluent gas, such as UHP nitrogen, zero nitrogenor zero air, shall not have a significant total sulfur concentra-tion.1.2 This test method may not detect sulfur compounds thatdo not volatilize under the conditions of the test.1.3 This test method covers the lab
6、oratory determinationand the at-line/on-line determination of total volatile sulfur ingaseous fuels, LPG, and LNG.1.4 This test method is applicable for total volatile sulfurdetermination in gaseous hydrocarbons, LPG, and LNG con-taining less than 0.35 mole % halogen(s).1.5 The values stated in SI u
7、nits are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health pr
8、actices and determine the applica-bility of regulatory limitations prior to use. See Sections 4.1,7.3, 7.4, 11.2, and Section 8.2. Referenced Documents2.1 ASTM Standards:2D1070 Test Methods for Relative Density of Gaseous FuelsD1072 Test Method for Total Sulfur in Fuel Gases byCombustion and Barium
9、Chloride TitrationD1265 Practice for Sampling Liquefied Petroleum (LP)Gases, Manual MethodD3588 Practice for Calculating Heat Value, CompressibilityFactor, and Relative Density of Gaseous FuelsD3609 Practice for Calibration Techniques Using Perme-ation TubesD4150 Terminology Relating to Gaseous Fuel
10、sD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4784 Specification for LNG Density Calculation ModelsD5287 Practice for Automatic Sampling of Gaseous FuelsD5503 Practice for Natural Gas Sample-Handling and Con-ditioning Systems for Pipeline InstrumentationD5504 Test Method
11、for Determination of Sulfur Compoundsin Natural Gas and Gaseous Fuels by Gas Chromatogra-phy and ChemiluminescenceD6228 Test Method for Determination of Sulfur Compoundsin Natural Gas and Gaseous Fuels by Gas Chromatogra-phy and Flame Photometric DetectionD6299 Practice for Applying Statistical Qual
12、ity Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD7166 Practice for Total Sulfur Analyzer Based On-line/At-line for Sulfur Content of Gaseous FuelsE617 Specification for Laboratory Weights and PrecisionMass StandardsE691 Practice for Conducting an Inte
13、rlaboratory Study toDetermine the Precision of a Test MethodF307 Practice for Sampling Pressurized Gas for Gas Analy-sis1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.05 on Determination ofSpecial Constituents of
14、Gaseous Fuels.Current edition approved Nov. 1, 2015. Published December 2015. Originallyapproved in 2010. Last previous edition approved as D7551-10. DOI: 10.1520/D755110R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
15、Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 ASTM Manuals:3ASTM MNL 72.3 GPA Standards:4GPA 2166 Obtaining Natural
16、 Gas Samples for Analysis byGas ChromatographyGPA 2174 Obtaining Liquid Hydrocarbon Samples forAnalysis by Gas Chromatography3. Terminology3.1 Defintions:For definitions of at-line instrument and on-line instrument seeTerminology D4150.3.2 Acronyms:3.2.1 LNGliquefied natural gas3.2.2 LPGliquefied pe
17、troleum gas3.2.3 NISTNational Institute of Standards and Technology3.2.4 NMiNederlands Meetinstituut3.2.5 NTRMNIST traceable reference material3.2.6 QAquality assurance3.2.7 QCquality control3.2.8 SO2ground state sulfur dioxide3.2.9 SO2*excited state sulfur dioxide3.2.10 SOxsulfur oxides3.2.11 SRMst
18、andard reference material3.2.12 UHPultra high purity3.2.13 UVultraviolet3.2.14 VSLVan Swinden Laboratorium4. Summary of Test Method4.1 Agaseous sample is injected into the analyzer, either bya sample valve, direct injection at a constant flow rate, or bysyringe. A LPG or LNG sample is vaporized in a
19、n appropriateexpansion chamber and injected into the analyzer by a samplevalve or a syringe or a sample valve connected to an expansionchamber. The gaseous sample then enters into a high tempera-ture combustion tube where the sulfur-containing compoundsin the sample are oxidized to SO2. Water produc
20、ed during thesample combustion is removed, as required, and the samplecombustion gases are then exposed to a source of continuous orpulsed UVlight.The SO2absorbs the energy from the UVlightto form SO2*. Fluorescence emitted from SO2* as it returns toSO2, is detected by a photomultiplier tube. The re
21、sulting signalis a measure of the sulfur contained in the sample. WarningExposure to excessive quantities of UV light is injurious tohealth. The operator shall avoid exposing any part of theirperson, especially their eyes, not only to direct UV light butalso to secondary or scattered radiation that
22、is present.4.2 The design and installation details for the on-line/at-lineprocess analyzer needs to conform to application-specificrequirements including, but not limited to, acceptable designpractices as described in Practice D7166, hazardous areaclassifications, safety practices, and regulatory re
23、quirements.Fig. 1 illustrates a general flow diagram applicable for anon-line/at-line process analyzer. Sample collection andconditioning, sample introduction and detection system aredepicted. Modifications to meet site-specific and/or applicationspecific requirements may be required.5. Significance
24、 and Use5.1 The sulfur content of gaseous hydrocarbons, LPG, andLNG used for fuel purposes contributes to total SOx emissionsand can lead to corrosion in engine and exhaust systems. Someprocess catalysts used in petroleum and chemical refining canbe poisoned by trace amounts of sulfur-bearing materi
25、als in thefeed stocks. This test method can be used to determine the totalvolatile sulfur content in process feeds, to control the totalvolatile sulfur content in finished products and, as applicable,to meet regulatory requirements. Practice D1072 has previ-ously been used for the measurement of tot
26、al sulfur in gaseousfuels.6. Apparatus6.1 FurnaceAn electric furnace held at a constant tem-perature in accordance with the analyzer manufacturers rec-ommendations (nominally 1000 to 1125C) sufficient to oxi-dize the entire sample to carbon dioxide and water and oxidizethe sulfur in the sample to SO
27、2.3MNL 7AManual on Presentation of Data and Control Chart Analysis, SeventhEdition, ASTM International, West Conshohocken. 2002.4Available from Gas ProcessorsAssociation (GPA), 6526 E. 60th St., Tulsa, OK74145, http:/.FIG. 1 General Flow DiagramOn-Line AnalyzerD7551 10 (2015)26.2 Combustion TubeA qu
28、artz tube constructed to allowthe direct injection of the sample into the heated oxidation zoneof the furnace by syringe or sample valve using either oxygenor air for the oxidation of the sample. Other tube materialssuitable for use at the furnace operating conditions can be usedso long as performan
29、ce is not degraded. The oxidation sectionshall be large enough to ensure complete conversion of thesample to carbon dioxide and water and oxidize the sulfur inthe sample to SO2.6.3 Flow ControlThe apparatus shall be equipped withflow controllers capable of maintaining a constant volumetricflow rate
30、of the carrier gases necessary for performing the totalsulfur analysis.6.4 DrierThe oxidation of the sample produces reactionproducts that include water vapor which, if in excess, must beremoved prior to measurement by the detector. This can beaccomplished with a membrane drying tube, or a permeatio
31、ndryer that utilizes a selective capillary action for water re-moval.6.5 UV Fluorescence DetectorA quantitative detector ca-pable of measuring light emitted from the fluorescence of SO2generated by continuous or pulsed UV light.NOTE 1For an on-line analyzer, detection of uncombusted hydrocar-bons in
32、 the UV Fluorescence Detector can be used to ensure completeconversion of the hydrocarbons to carbon dioxide and water and tominimize the potential for coke formation in the analytical system.6.6 Sample Inlet SystemEither of the following two typesof sample inlet systems can be used.6.6.1 Sample Val
33、ve SystemThe system provides a gas-sampling valve, or an LPG or LNG gas or liquid samplingvalve with an expansion chamber, or both, with access to theinlet of the oxidation area. The system is swept by the carriergas at the manufacturers recommended flow rate.6.6.2 Sample InjectionThe sample inlet s
34、ystem for gas-eous samples shall be capable of allowing the quantitativedelivery of the material to be analyzed into an inlet carrierstream which directs the sample into the oxidation zone at acontrolled and repeatable rate. For a laboratory analysis, asyringe drive mechanism that discharges the sam
35、ple from thesyringe at a rate of approximately 1 mL/s is required. For atline and on-line analysis a constant volumetric flow ratedelivery device is used.6.7 Strip Chart Recorder, equivalent electronic data logger,integrator or, recorder (optional).7. Reagents7.1 Purity of ReagentsReagent grade chem
36、icals shall beused in tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades may beused, provided it is first ascertained that
37、 the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Inert GasArgon or helium only, high purity grade(that is, chromatography or zero grade), 99.998 % minimumpurity, moisture 5 mg/kg maximum, as required.7.3 OxygenHigh purity, that is, c
38、hromatography or zerograde, 99.75 % minimum purity, moisture 5 mg/kg maximum,dried over molecular sieves, as required. WarningOxygenvigorously accelerates combustion.7.4 AirUse dry, sulfur free air, that is, chromatographygrade or zero grade, 40 Cdew point or lower, as required.Nitrogen/oxygen or he
39、lium/oxygen bottled gas blends contain-ing no more than 30 % oxygen can also be used, as required.WarningNever use pure oxygen as a substitute for air onanalyzers designed to operate using air as a carrier gas.7.5 Calibration StandardsCertified liquid or gas phasecalibration standards from commercia
40、l sources or calibrationgases prepared using certified permeation tube devices arerequired (see Notes 2 and 3). Accurate volatile sulfur contain-ing standards are required for quantization of the volatile totalsulfur content. Permeation tubes and compressed gas standardsshould be stable, of high pur
41、ity, and of the highest availableaccuracy. Use of standards consisting of a sulfur compoundand matrix similar to samples to be analyzed is recommended.NOTE 2Other sulfur sources and diluent materials can be used ifprecision and accuracy are not degraded. The use of solvent basedcalibration standards
42、 that are liquid at ambient temperatures and pressuresis not recommended.NOTE 3Calibration standards are typically re-mixed and re-certifiedon a regular basis depending upon frequency of use and age. LPGcalibration standards have a typical useful life of about 612 months.NOTE 4Enhanced oxygen contai
43、ning combustion gasses, such as30 % Oxygen balance Helium, Nitrogen, and/or Argon, can be used ifprecision and accuracy are not degraded.NOTE 5Warning: Compressed gas cylinders as well as sulfurcompounds contained in permeation tubes may be flammable and harmfulor fatal if ingested or inhaled. Perme
44、ation tubes and compressed gasstandards should only be handled in well ventilated locations away fromsparks and flames. Improper handling of compressed gas cylinderscontaining air, nitrogen, helium, or other gasses can result in unsafeconditions that can cause severe damage to equipment and signific
45、antharm, including death, to people. Rapid release of nitrogen or helium canresult in asphyxiation. Compressed air supports combustion.7.5.1 Permeation DevicesStandards containing volatilesulfur compounds can be made from permeation tubes, one foreach selected sulfur species, gravimetrically calibra
46、ted andcertified at a convenient operating temperature. With constanttemperature, calibration gases covering a wide range of con-centration can be generated by varying and accurately measur-ing the flow rate of diluent gas passing over the permeationtubes. These calibration gases can be used to cali
47、brate theanalyzer system.7.5.1.1 Permeation System Temperature ControlPermeation devices are maintained at the calibration tempera-ture within 60.1 C.7.5.1.2 Permeation System Flow ControlThe permeationflow system measures diluent gas flow over the permeationtubes within an accuracy of 62%.7.5.1.3 P
48、ermeation tubes are inspected and weighed to thenearest 0.01 mg on at least a monthly basis using a balancecalibrated against Specification E617 Class 1 weights orequivalent. Analyte concentration is calculated by weight lossand dilution gas flow rate as per Practice D3609. Permeationtubes are repla
49、ced when the liquid contents are reduced to lessthan 10 % of the initial mass or when the permeation surface isD7551 10 (2015)3unusually discolored or otherwise compromised. Permeationtube disposal shall be in accordance with all applicableregulations.7.5.2 Compressed Gas StandardsAs an alternative topermeation tubes, blended gaseous standards containing vola-tile sulfur-containing compounds in nitrogen, helium methaneor other base gas may be used. Care must be exercised whenusing compressed gas standards since th
