1、Designation:D550408 Designation: D5504 12Standard Test Method forDetermination of Sulfur Compounds in Natural Gas andGaseous Fuels by Gas Chromatography andChemiluminescence1This standard is issued under the fixed designation D5504; the number immediately following the designation indicates the year
2、 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 is primarily for the determination of s
3、peciated volatile sulfur-containing compounds in high methanecontent gaseous fuels such as natural gas. It has been successfully applied to other types of gaseous samples including air, digester,landfill, and refinery fuel gas. The detection range for sulfur compounds, reported as picograms sulfur,
4、is ten (10) to one million(1 000 000). This is equivalent to 0.01 to 1 000 mg/m3, based upon the analysis ofa1ccsample.1.2 The range of this test method may be extended to higher concentration by dilution or by selection of a smaller sample loop.NOTE 1 Dilution will reduce method precision.1.3 This
5、test method does not purport to identify all sulfur species in a sample. Only compounds that are eluted through theselected column under the chromatographic conditions chosen are determined. The detector response to sulfur is equimolar for allsulfur compounds within the scope (1.1) of this test meth
6、od. Thus, unidentified compounds are determined with equal precisionto that of identified substances. Total sulfur content is determined from the total of individually quantified components.1.4 The values stated in SI units are standard. The values stated in inch-pound units are for information only
7、.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Do
8、cuments2.1 ASTM Standards:2D1072 Test Method for Total Sulfur in Fuel Gases by Combustion and Barium Chloride TitrationD1945 Test Method for Analysis of Natural Gas by Gas ChromatographyD3609 Practice for Calibration Techniques Using Permeation TubesD4468 Test Method for Total Sulfur in Gaseous Fuel
9、s by Hydrogenolysis and Rateometric ColorimetryE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography Practice for TestingFlame Ionization Detectors Used in Gas or Supercritical
10、Fluid ChromatographyE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Summary of Test Method3.1 The analysis of gaseous sulfur compounds is challenging due to the reactivity of these substances. They are difficult tosample and analyze. Ideally, analy
11、sis is performed on-site to eliminate sample deterioration as a factor in analysis. Sampling mustbe performed using non-reactive containers, such as Silcosteel3lined vessels, Tedlar4bags with polypropylene fittings or theequivalent. Tedlar4bag samples require protection from light and heat. Laborato
12、ry equipment must be inert or passivated to ensurereliable results.3.2 Aone cc (mL) sample is injected into a gas chromatograph where it is eluted through a megabore, thick film, methyl siliconeliquid phase, open tubular partitioning column or other suitable column, and separated into its individual
13、 constituents.1This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination ofSpecial Constituents of Gaseous Fuels.Current edition approved June 15, 2008.1, 2012. Published July 2008.November 2012. Origina
14、lly approved in 1994. Last previous edition approved in 20062008 asD550401(2006).D5504 08. DOI: 10.1520/D5504-08.10.1520/D5504-12.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume informatio
15、n, refer to the standards Document Summary page on the ASTM website.3Silcosteel is a trademark of Restek Corporation, 110 Benner Circle Bellefonte, PA, 16823.4Tedlar is a trademark of DuPont.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indica
16、tion of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be con
17、sidered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3 Sulfur Chemiluminescence DetectionAs sulfur compounds elute from the gas chromatographic column, they areprocessed in a flame ionization detector (FID)
18、or a heated combustion zone. The products are collected and transferred to a sulfurchemiluminescence detector (SCD). This technique provides a sensitive, selective, linear response to volatile sulfur compoundsand may be used while collecting hydrocarbon and fixed gas data from a FID.3.3.1 Detectors
19、in Series with a SCDASCD can frequently be used in series with other fixed gas and hydrocarbon detectors.However, regulatory bodies may question detector compatibility and require demonstration of equivalence between a SCD in amulti-detector system and a SCD operated using a FID or combustion zone.
20、The user is referred to USEPA Method 301 for anexample of a general equivalence procedure.3.3.2 Alternative DetectorsThis test method is written for the sulfur chemiluminescent detector but other sulfur specificdetectors can be used provided they have sufficient sensitivity, respond to all eluted su
21、lfur compounds, do not suffer frominterferences and satisfy quality assurance criteria. Regulatory agencies may require demonstration of equivalency of alternativedetection systems to the SCD.4. Significance and Use4.1 Many sources of natural and petroleum gases contain sulfur compounds that are odo
22、rous, corrosive, and poisonous tocatalysts used in gaseous fuel processing.4.2 Low ppm amounts of sulfur odorants are added to natural gas and LP gases for safety purposes. Some odorants are unstableand react to form compounds having lower odor thresholds. Quantitative analysis of these odorized gas
23、es ensures that odorantinjection equipment is performing to specification.4.3 Although not intended for application to gases other than natural gas and related fuels, this test method has been successfullyapplied to fuel type gases including refinery, landfill, cogeneration, and sewage digester gas.
24、 Refinery, landfill, sewage digester andother related fuel type gases inherently contain volatile sulfur compounds that are subject to federal, state, or local control. Themethane fraction of these fuel type gases are occasionally sold to distributors of natural gas. For these reasons, both regulato
25、ryagencies and production and distribution facilities may require the accurate determination of sulfur to satisfy regulatory, productionor distribution requirements. Fuel gases are also used in energy production or are converted to new products using catalysts thatare poisoned by excessive sulfur in
26、 the feed gas. Industry frequently requires measurement of sulfur in these fuel type gases toprotect their catalyst investments.4.4 Analytical MethodsGas chromatography (GC) is commonly used in the determination of fixed gas and organiccomposition of natural gas (Test Method D1945). Other standard A
27、STM methods for the analysis of sulfur in fuel gases includeTest Methods D1072 and D4468 for total sulfur and Test Methods D4010 and D4884 for hydrogen sulfide.5. Apparatus5.1 ChromatographAny gas chromatograph of standard manufacture, with hardware necessary for interfacing to achemiluminescence de
28、tector and containing all features necessary for the intended application(s) can be used. Chromatographicparameters must be capable of obtaining retention time repeatability of 0.05 min (3 s) throughout the scope of this analysis.5.1.1 Sample Inlet SystemA sample inlet system capable of operating co
29、ntinuously at the maximum column temperature isused. A split/splitless injection system capable of splitless operation and split control from 10:1 up to 50:1 may be used withcapillary columns, or when interferants are encountered. An automated gas sampling valve is required for many applications. Th
30、einlet system must be conditioned or constructed of inert material and evaluated frequently for compatibility with trace quantitiesof reactive sulfur compounds.5.1.2 Carrier and Detector Gas ControlConstant flow control of carrier and detector gases is critical for optimum andconsistent analytical p
31、erformance. Control is achieved by use of pressure regulators and fixed flow restrictors. The gas flow ismeasured by appropriate means and adjusted. Mass flow controllers, capable of maintaining gas flow constant to 61 % at the flowrates necessary for optimal instrument performance can be used.5.1.3
32、 DetectorSulfur compounds are processed using a flame ionization detector (FID), a heated combustion zone or a similardevice. The products are collected and delivered to a sulfur chemiluminescence detector (SCD).5.1.3.1 FIDThe detector must meet or exceed the specifications in Table 1 of Practice E5
33、94 while operating withinmanufacturers specifications. The detector must be capable of operating at the maximum column temperature. The flow path fromthe injection system through the column to the FID must remain at or above the column temperature throughout the analysis. TheFID must allow for the i
34、nsertion of a SCD sampling probe into the flame without compromising the ability of the FID to detecthydrocarbons. Flow rates of air and hydrogen or, alternatively of oxygen and hydrogen, must be optimized to produce a hydrogenrich flame or combustion zone that is capable of combusting hydrocarbons.
35、 This is necessary to minimize matrix effects. Whenperforming the simultaneous detection of hydrocarbons is necessary, a FID and heated combustion zone can be used in series. Zeroair is necessary when performing the simultaneous determination of sulfur gases and hydrocarbons.5.1.3.2 SCDThe sulfur ch
36、emiluminescence detector shall meet or exceed the following specifications: (1) greater than 105linearity, (2) less than 5 pg S/s sensitivity, (3) greater than 106selectivity for sulfur compounds over hydrocarbons, (4)noquenching of sulfur compound response, and (5) no interference from co-eluting c
37、ompounds at the usual GC sampling volumes.5.1.3.3 Heated Combustion ZoneSulfur compounds eluting from the chromatographic column are processed in a heatedhydrogen rich combustion zone or a flame ionization detector fitted to the end of the column. Products are transferred underD5504 122reduced press
38、ure to the reaction chamber of a chemiluminescence detector.An excess of ozone present in the chamber reacts withthe sulfur combustion product(s) to liberate blue (480 nm) and ultraviolet light (260 nm).5.1.3.4 SCD operation is based on the chemiluminescence (light emission) produced by the reaction
39、 of ozone with anunidentified sulfur species produced in a combustion zone, flame ionization detector or related device. The chemiluminescentsulfur species is the subject of on-going research. The appendix describes two chemiluminescence reaction models. The sulfurcombustion product(s) and an excess
40、 of ozone are drawn into a low pressure (20 Torr) reaction cell. The ozone reacts to produceblue light (480 nm), oxygen, and other products. A blue sensitive photomultiplier tube detects the emitted light which is thenamplified for display or output to a data collection system.5.2 ColumnA variety of
41、 columns can be used in the determination of sulfur compounds. Typically, a 60 m 3 0.54 mm IDfused silica open tubular column containinga5mfilmthickness of bonded methyl silicone liquid phase is used. The selectedcolumn must provide retention and resolution characteristics such as listed in Table 2
42、and illustrated in Fig. 1. The column mustbe inert towards sulfur compounds. The column must also demonstrate a sufficiently low liquid phase bleed at high temperaturesuch that loss of the SCD response is not encountered while operating the column at 200C.5.3 Data Acquisition:5.3.1 RecorderA 0 to 1
43、mV range recording potentiometer or equivalent, with a full-scale response time of2sorless canbe used.5.3.2 IntegratorAn electronic integrating device or computer can be used. A dual channel system is necessary forsimultaneous acquisition of both the FID and SCD signals. The device and software must
44、 have the following capabilities:5.3.2.1 Graphic presentation of the chromatogram.5.3.2.2 Digital display of chromatographic peak areas.5.3.2.3 Identification of peaks by retention time or relative retention time, or both.5.3.2.4 Calculation and use of response factors.TABLE 1 Example Retention Time
45、s Using 4 Capillary Column(30 m 3 0.32 mm)Conditions as in Table 2Compound Ave. RT min Compound Ave. RT minMethane 1.458 ?S 16.363Ethane 1.730 n-Octane 16.423Ethylene 1.733 ?S 16.425Hydrogen Sulfide 2.053 ?S 16.592Propylene 2.550 ?S 16.692Carbonyl Sulfide 2.586 ?-EtThiophene 16.983Propane 2.679 ?S 1
46、7.183Sulfur Dioxide 2.815 ?S 17.319i-Butane 4.422 ?S 17.631Butene-1 5.263 ?S 17.754n-Butane 5.578q m therefore, response factors for all calibration components should be within 5 % of theresponse factor for hydrogen sulfide. Failure to satisfy this criteria indicates either calibration standard degr
47、adation or failure ofthe SCD heated combustion zone, flame ionization detector (FID), or related device.8.2.5 Calculate the relative response factor for each sulfur compound:Fn5 Cn/An! (1)D5504-12_1where:Fn= response factor of compound,Cn= concentration of the sulfur compound in the mixture, andAn=
48、peak area of the sulfur compound in the mixture.The response factor (Fn) of each single sulfur compound should be within 5 % of Fnfor hydrogen sulfide. Fig. 1 provides anFIG. 5 Example of Matrix Interference. Changing the Sample Size Should Give a Change in ResponseD5504 127example of a typical chro
49、matogram and Table 4 shows the data and calibration report. Table 3 contains information useful forcalibration calculations.9. Procedure9.1 Many operating conditions can be used to perform sulfur gas speciation and quantitation. Minimum criteria for acceptableoperating conditions are as stated in 7.1. In addition, it is advisable and required for regulatory purposes to establish the limit ofdetection (LOD) for a SCD system.9.2 Sampling and Preparation of SamplesAppropriate sampling procedures are critical for meaningful sulfur determinationand must be tailore
