ASTM D6667-2004(2010) 0625 Standard Test Method for Determination of Total Volatile Sulfur in Gaseous Hydrocarbons and Liquefied Petroleum Gases by Ultraviolet Fluorescence《紫外荧光法测定.pdf

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1、Designation: D6667 04 (Reapproved 2010)Standard Test Method forDetermination of Total Volatile Sulfur in GaseousHydrocarbons and Liquefied Petroleum Gases by UltravioletFluorescence1This standard is issued under the fixed designation D6667; the number immediately following the designation indicates

2、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 determination of tot

3、alvolatile sulfur in gaseous hydrocarbons and liquefied petro-leum (LP) gases. It is applicable to analysis of natural,processed, and final product materials containing sulfur in therange of 1 to 100 mg/kg (Note 1).NOTE 1An estimate of pooled limit of quantification (PLOQ), infor-mation regarding sa

4、mple stability and other general information derivedfrom the inter-laboratory study on precision can be referenced in theASTM research report.21.2 This test method may not detect sulfur compounds thatdo not vaporize under the conditions of the test.1.3 This test method is applicable for total volati

5、le sulfurdetermination in LP gases containing less than 0.35 % (mass/mass) halogen(s).1.4 The values stated in SI units are to be regarded asstandard.1.5 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

6、standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. See 3.1 andSections 6 and 7 for specific warning statements.2. Referenced Documents2.1 ASTM Standards:3D1070 Test Methods for Relative Density of Gaseous FuelsD1265

7、 Practice for Sampling Liquefied Petroleum (LP)Gases, Manual MethodD3700 Practice for Obtaining LPG Samples Using a Float-ing Piston CylinderD5287 Practice for Automatic Sampling of Gaseous FuelsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate Anal

8、yticalMeasurement System PerformanceF307 Practice for Sampling Pressurized Gas for Gas Analy-sis2.2 Gas Processor Association (GPA) Standards:4GPA 2166 Obtaining Natural Gas Samples for Analysis byGas ChromatographyGPA 2174 Obtaining Liquid Hydrocarbon Samples forAnalysis by Gas Chromatography3. Sum

9、mary of Test Method3.1 Aheated sample valve is used to inject gaseous samples.Liquefied petroleum gas (LPG) samples are injected by asample valve connected to a heated expansion chamber. Thegaseous sample then enters a high temperature combustiontube where sulfur is oxidized to sulfur dioxide (SO2)i

10、nanoxygen rich atmosphere. Water produced during the samplecombustion is removed and the sample combustion gases arenext exposed to ultraviolet (UV) light. The SO2absorbs theenergy from the UV light and is converted to an excited sulfurdioxide (SO2). Fluorescence emitted from the excited SO2*asit re

11、turns to a stable state SO2*is detected by a photomultipliertube, the resulting signal is a measure of the sulfur contained inthe sample. (WarningExposure to excessive quantities ofultraviolet light is injurious to health. The operator shall avoidexposing their person, especially their eyes, not onl

12、y to directUV light but also to secondary or scattered radiation that ispresent.)4. Significance and Use4.1 The sulfur content of LPG, used for fuel purposes,contributes to SOx emissions and can lead to corrosion inengine and exhaust systems. Some process catalysts used inpetroleum and chemical refi

13、ning can be poisoned by sulfur1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 2001. Last

14、previous edition approved in 2004 as D666704. DOI:10.1520/D6667-10.2Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1506.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at

15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from Gas Processors Association (GPA), 6526 E. 60th St., Tulsa, OK74145.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock

16、en, PA 19428-2959, United States.bearing materials in the feed stocks. This test method can beused to determine sulfur in process feeds, to measure sulfur infinished products, and can also be used for compliance deter-minations when acceptable to a regulatory authority.5. Apparatus5.1 FurnaceAn elec

17、tric furnace held at a temperature(1075 6 25C) sufficient to pyrolyze the entire sample andoxidize sulfur to SO2.5.2 Combustion TubeA quartz combustion tube con-structed to allow the direct injection of the sample into theheated oxidation zone of the furnace. The combustion tubeshall have side arms

18、for the introduction of oxygen and carriergas. The oxidation section shall be large enough (see Fig. 1)toensure complete combustion of the sample (see 11.3). Fig. 1depicts a typical combustion tube. Other configurations areacceptable when precision is not degraded.5.3 Flow ControlThe apparatus shall

19、 be equipped withflow controllers capable of maintaining a constant supply ofoxygen and carrier gas at the specified rates.5.4 Drier TubeThe apparatus shall be equipped with amechanism for the removal of water vapor formed duringsample combustion. This can be accomplished with a mem-brane drying tub

20、e, or a permeation dryer that utilizes aselective capillary action for water removal.5.5 UV Fluorescence DetectorA quantitative detector ca-pable of measuring light emitted from the fluorescence ofsulfur dioxide by UV light.5.6 Sample Inlet SystemThe system provides a heatedgas-sampling valve, or a

21、LP gas-sampling valve, or both, witha heated expansion chamber, connected to the inlet of theoxidation area, Fig. 2. The system is swept by an inert carriergas and shall be capable of allowing the quantitative deliveryof the material to be analyzed into the oxidation zone at acontrolled and repeatab

22、le rate of approximately 30 mL/min.Fig. 3 provides an example.5.7 Strip Chart Recorder, equivalent electronic data logger,integrator or, recorder (optional).6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in tests. Unless otherwise indicated, it is intended that allreagents sha

23、ll conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society,5where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy

24、of the determination.6.2 Inert GasArgon or helium only, high purity grade(that is, chromatography or zero grade), 99.998 % min purity,moisture 5 mg/kg max. (WarningArgon or helium may be acompressed gas under high pressure (7.1).6.3 OxygenHigh purity (that is chromatography or zerograde), 99.75 % mi

25、n purity, moisture 5 mg/kg max, dried overmolecular sieves. (WarningOxygen vigorously acceleratescombustion and may be compressed gas under high pressure(7.1).6.4 Calibration StandardsCertified calibration standardsfrom commercial sources or calibration gases prepared usingcertified permeation tube

26、devices are required. Table 1 lists thesulfur source material and diluent matrices used during theinter-laboratory study (Notes 2 and 3).NOTE 2Other sulfur sources and diluent materials may be used ifprecision and accuracy are not degraded.5Reagent Chemicals, American Chemical Society Specifications

27、, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc

28、. (USPC), Rockville,MD.FIG. 1 Example of a Typical Direct Inject Quartz Pyrolysis TubeD6667 04 (2010)2FIG. 2 Example of Orientation of Total Sulfur Analyzer and Gas or Liquid Sampling ValveFIG. 3 Sample Inlet System Flow PathD6667 04 (2010)3NOTE 3Calibration standards are typically re-mixed and re-c

29、ertifiedon a regular basis depending upon frequency of use and age. Thesecalibration standards may have a useful life of about 6 to 12 months.6.5 Quality Control (QC) Samples, preferably are portionsof one or more gas or LP gas materials that are stable andrepresentative of the samples of interest.7

30、. Hazards7.1 High temperature, flammable hydrocarbons, and gasesunder high pressures occur in the test method. Use materialsthat are rated for containing these pressurized hydrocarbons inall sample containers and sample transfer apparatus. Exerciseextra care when using flammable materials near the o

31、xidativefurnace.8. Sampling8.1 Obtain a sample in accordance with Practices F307,D1265, D3700, D5287,orGPA 2174 or GPA 2166. Analyzesamples as soon as possible after taking from bulk supplies toprevent loss of sulfur or contamination due to exposure orcontact with sample containers.8.2 If the sample

32、 is not used immediately, then thoroughlymix it in its container prior to taking a test specimen. The useof segregated or specially treated sample containers can helpreduce sample cross-contamination and improve sample sta-bility.9. Preparation of Apparatus9.1 Assemble and check the apparatus for le

33、aks according tomanufacturers instructions.9.2 Typical apparatus adjustments and conditions are listedin Table 2.9.3 Adjust instrument sensitivity and baseline stability andperform instrument-blanking procedures following manufac-turers guidelines.10. Calibration and Standardization10.1 Consult Tabl

34、e 3 and select a calibration range based onthe anticipated sulfur concentrations present in samples to beanalyzed, preferably using a sulfur compound and a diluenttype representative of the samples to be analyzed (Note 4).Table 3 is representative of typical ranges, but narrower rangesthan those ind

35、icated may be used if desired. However, themethod precision using narrower ranges than those indicatedhas not been determined. Ensure the standards used forcalibration bracket the concentrations of the samples beinganalyzed.NOTE 4The number of standards used per curve may vary.10.2 With the sample v

36、alve in the load position, connect thepressurized sample container to the sample valve of the sampleinlet system.10.3 Obtain a quantitative measurement of the injectedmaterial by filling the sample loop of the sample valve systemfor the matrix being analyzed (see Table 2) (Notes 5 and 6).NOTE 5Injec

37、tion of a constant or similar sample size for all materialsanalyzed in a selected operating range promotes consistent combustionconditions and may simplify result calculations.NOTE 6An automatic sample transfer and injection device may beused.10.3.1 Flush the sample loop with sufficient calibrant to

38、assure that the material to be injected is representative.10.3.2 For LPG samples, if bubbles are present in theviewable portion of the liquid column, flush the sample loop tointroduce a new liquid-full sample portion.10.4 Start the analyzer and inject the calibration materialaccording to the manufac

39、turers instructions.10.5 Calibrate the instrument using one of the followingtechniques.10.5.1 Multi-point Calibration:10.5.1.1 When the apparatus features an internal self-calibration routine, analyze the calibration standards and blankthree times using the procedures described in 10.2-10.4.10.5.1.2

40、 Calibrate the analyzer according to the manufac-turers instructions to yield sulfur concentration (see Section13). This curve is typically linear and system performance shallbe checked at least once per day, each day of use. (Note 7).NOTE 7Other calibration curve techniques may be used when accu-ra

41、cy and precision are not degraded. The frequency of calibration may bedetermined by the use of quality control charts or other quality assurance/quality control techniques.10.5.2 One-point Calibration:TABLE 1 Typical Standard MaterialsSulfur Source DiluentDimethyl sulfide n, butaneiso-butanepropylen

42、epropaneTABLE 2 Typical Operating ConditionsSample inlet system temperature 85 6 20CSample injection system carrier gas 2530 mL/minFurnace temperature 1075 6 25CFurnace oxygen flow meter setting 375450 mL/minInlet oxygen flow meter setting 1030 mL/minInlet carrier flow meter setting 130160 mL/minGas

43、 sample size 1020 mLLPG sample size 15 LTABLE 3 Typical Sulfur Calibration Ranges and StandardConcentrationsCurve ISulfur mg/kgCurve IISulfur mg/kgBlank Blank5.00 10.0010.00 50.00100.00TABLE 4 Repeatability (r) and Reproducibility (R)Concentration(mg/kg S)rR1 0.1 0.35 0.6 1.610 1.2 3.125 2.9 7.850 5

44、.8 15.6100 11.5 31.3D6667 04 (2010)410.5.2.1 Utilize a calibration standard (6.4) with a sulfurcontent close to that of the samples to be analyzed (625 %max.).10.5.2.2 Follow the instrument manufacturers instructionsto establish an instrument zero (instrument blank) by conduct-ing an analysis run wi

45、thout injection of the calibration stan-dard.10.5.2.3 Perform measurements of the calibration standard aminimum of three times.10.5.2.4 Calculate a calibration factor K, in counts pernanogram of sulfur (counts/ng S) as described in 12.2.11. Procedure11.1 Obtain a test specimen using the procedure de

46、scribedin Section 8. Typically the sulfur concentration in the testspecimen is less than the concentration of the highest standardand greater than the concentration of the lowest standard usedin the calibration.11.2 Measure the response for the test specimen using oneof the procedures described in 1

47、0.2-10.4.11.3 Inspect the combustion tube and other flow pathcomponents to verify complete oxidation of the test specimen.11.3.1 Reduce the rate of injection or the sample size, orboth, of the specimen into the furnace when coke or sooting isobserved.11.4 Cleaning and Re-calibrationClean any coked o

48、rsooted parts according to the manufacturers instructions.Afterany cleaning or adjustment, assemble and check the apparatusfor leaks. Repeat instrument calibration prior to reanalysis ofthe test specimen.11.5 To obtain one result, measure each test specimen threetimes and calculate the average detec

49、tor response.11.6 Density values needed for calculations are to bemeasured using Test Methods D1070 or equivalent, at thetemperature at which the sample was tested (Note 8).NOTE 8When sample matrix compositions are known, other tech-niques may be used to derive sample density, provided accuracy andprecision are not degraded.12. Calculation12.1 For analyzers calibrated using an internal self-calibration, calculate the sulfur content in the test specimen asfollows:Sulfur, mg/kg 5G 3 ds(1)where:d = density of standard mixture, g/mL,s = density