1、Designation: D4891 13 (Reapproved 2018)Standard Test Method forHeating Value of Gases in Natural Gas and Flare GasesRange by Stoichiometric Combustion1This standard is issued under the fixed designation D4891; the number immediately following the designation indicates the year oforiginal adoption or
2、, 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 the heatingvalue of natural gases
3、and similar gaseous mixtures within therange of composition shown in Table 1, and Table 2 that coversflare components but is not intended to limit the components tobe measured in flare gases.1.2 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.3 This international standard was developed in accor-dance with internationally recognized principles on s
5、tandard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1826 Test Method for Calorific (Heating)
6、Value of Gases inNatural Gas Range by Continuous Recording CalorimeterE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 EPA Standard:3EPA-600 /2-85-106 Evaluation of the Efficiency of IndustrialFlares: Flare Head Design and Gas Composition3. Terminol
7、ogy3.1 All of the terms defined in Test Method D1826 areincluded by reference.3.2 Definitions of Terms Specific to This Standard:3.2.1 combustion ratio, nthe ratio of combustion air togaseous fuel.3.2.2 burned gas parameter, na property of the burned gasafter combustion which is a function of the co
8、mbustion ratio.3.2.3 critical combustion ratio, n for a specific burned gasparameter, the combustion ratio at which a plot of burned gasparameter versus combustion ratio has either maximum valueor maximum slope.3.2.4 combustion air requirement index (CARI), nis theamount of air required for complete
9、 combustion of the gasbeing measured and can be used to index against othermeasured values such as the Wobbe Index or Heating Value.3.2.5 stoichiometric ratio, nthe combustion ratio when thequantity of combustion air is just sufficient to convert all of thecombustibles in the fuel to water and carbo
10、n dioxide.4. Summary of Test Method4.1 Air is mixed with the gaseous fuel to be tested. Themixture is burned and the air-fuel ratio is adjusted so thatessentially a stoichiometric proportion of air is present. Moreexactly, the adjustment is made so that the air-fuel ratio is in aconstant proportion
11、to the stoichiometric ratio that is a relativemeasure of the heating value. To set this ratio, a characteristicproperty of the burned gas is measured, such as temperature oroxygen concentration.5. Significance and Use5.1 This test method provides an accurate and reliableprocedure to measure the tota
12、l heating value of a fuel gas, ona continuous basis, which is used for regulatory compliance,custody transfer, and process control.5.2 Some instruments which conform to the requirementsset forth in this test method can have response times on theorder of 1 min or less and can be used for on-line meas
13、urementand control.5.3 The method is sensitive to the presence of oxygen andnonparaffin fuels. For components not listed and compositionranges that fall outside those in Table 1 and Table 2, modifi-cations in the method and changes to the calibration gas orgasses being used may be required to obtain
14、 correct results.1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.03 on Determination ofHeating Value and Relative Density of Gaseous Fuels.Current edition approved Sept. 1, 2018. Published September 2018. Originall
15、yapproved in 1989. Last previous edition approved in 2013 as D4891 13. DOI:10.1520/D4891-13R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Documen
16、t Summary page onthe ASTM website.3Available from United States Environmental Protection Agency (EPA), ArielRios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004, http:/www.epa.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United State
17、sThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trad
18、e (TBT) Committee.16. Apparatus6.1 A suitable apparatus for carrying out the stoichiometriccombustion method will have at least the following fourcomponents: flow meter or regulator, or both; combustionchamber; burned gas sensor; and electronics. The requirementfor each of these components is discus
19、sed below. The detaileddesign of each of these components can vary. Three differentapparatus are shown in Fig. 1, Fig. 2 and Fig. 3. In each figurethe equivalent of the four necessary components are enclosedin dashed lines.6.2 OverviewAir and fuel enter the apparatus and the flowof each is measured.
20、 Alternatively, only one gas flow need bemeasured if the flow of the other is kept the same duringmeasurement and calibration. This is illustrated in Fig. 2. Nextthere is a combustion chamber in which the air and fuel aremixed and burned. This can be as simple as a bunsen or meekerburner, but precau
21、tions should be taken that subsequent mea-surements of burned gas characteristics are not influenced byambient conditions. Finally, there is a sensor in the burned gaswhich measures a property of this gas that is sensitive to thecombustion ratio and has a unique feature at the stoichiometricratio. T
22、wo such properties are temperature and oxygenconcentrations, and either can be measured.6.3 Flow Meter or Regulator, or bothThe flow measure-ment part of the apparatus should have an accuracy andprecision of the order of 0.1 %. Likewise, if the flow is to bekept constant, the flow regulator should m
23、aintain this constantvalue within 0.1 %. The meter or regulator for natural gas mustmaintain this precision and accuracy over the density andviscosity ranges consistent with the composition range in Table1 or Table 2.6.4 Combustion Chamber:6.4.1 There are two different types of combustion chambersth
24、at may be used. In the first type the air and fuel are mixed andburned in a single burner. The apparatus shown in Fig. 1 hasthis type of combustion chamber.6.4.2 In the second type of combustion chamber, the air andfuel are each divided into two streams, and combustion takesplace simultaneously in t
25、wo burners. The division of air flowmust be such that the proportion of air going to each burneralways remains the same. Likewise the division of fuel flowmust always remain the same even through fuel compositionchanges.Another requirement is that the flow divisions be suchthat one burner has a mixt
26、ure with a slightly higher combustionTABLE 1 Natural Gas Components and Range of CompositionCoveredCompound Concentration Range, mole, %Helium 0.01 to 5Nitrogen 0.01 to 20Carbon dioxide 0.01 to 10Methane 50 to 100Ethane 0.01 to 20Propane 0.01 to 20n-butane 0.01 to 10isobutane 0.01 to 10n-pentane 0.0
27、1 to 2Isopentane 0.01 to 2Hexanes and heavier 0.01 to 2TABLE 2 Natural Gas Components and Range of CompositionCoveredACompound CAS NumberVolatile AnalytesAcetone 67-64-1Acetonitrile 75-05-8Acrolein 107-05-8Acrylonitrile 107-13-1Benzene 71-43-2 21,3-Butadiene 106-99-0Carbon disulfide 75-15-0Chloroben
28、zene 108-90-7Cumene(isopropylbenzene)98-82-81,2-Dibromoethane 106-93-4Ethylbenzene 100-41-4 2,2,4Hexane 110-54-3Methanol 67-56-1Methyl isobutyl ketone 108-10-1Methyl t-butyl ether 1634-04-4Methylene chloride 75-09-2Nitrobenzene 98-95-3Nitropropane 79-46-9Pentane2 109-66-0Styrene 100-42-5Tetrachloroe
29、thene 127-18-4Toluene 108-88-3Trichloroethene 79-01-6Trimethylpentane 2 540-84-1Xylenes (mixed isomers) 1330-20-7Trimethylpentane 2 540-84-1Xylenes (mixed isomers) 1330-20-7Semi-volatile AnalytesAcenaphthene 83-32-9Acenaphthylene 208-96-8Aniline 62-53-3Anthracene 120-12-7Benzidine1 92-87-5Benzaanthr
30、acene 56-55-3Benzobfluoranthene 205-99-2Benzokfluoranthene 207-08-9Benzog,h,iperylene 191-24-2Benzoapyrene 50-32-8Benzoepyrene2 192-97-2Biphenyl2, 92-52-4Cresol (mixed isomers) 1319-77-3Chrysene 218-01-9Dibenza,hanthracene 53-70-3Dibenzofuran 132-64-9Dibenzo(a,e)pyrene 192-65-43,3- Dimethoxybenzidin
31、e 119-90-4Dimethylaminobenzene 60-11-77,12-Dimethylbenz(a)anthracene57-97-63,3- Dimethylbenzidine 119-93-7,-Dimethylphenethylamine122-09-82,4-Dimethylphenol 105-67-9Fluoranthene 206-44-0Fluorene 86-73-7Indeno(1,2,3-cd)pyrene 193-39-5Isophorone 78-59-13-Methylcholanthrene 56-49-52-Methylnaphthalene 9
32、1-57-6Naphthalene 91-20-3Perylene2 198-55-0Phenanthrene 85-01-8Phenol 108-95-21,4-Phenylenediamine 106-50-3Pyrene 129-00-0o-Toluidine 95-53-4AldehydesMethanol 67-56-1Formaldehyde 50-00-0Acetaldehyde 75-07-0D4891 13 (2018)2ratio than the other. The apparatus shown in Fig. 2 has this typeof combustion
33、 chamber.6.4.3 A third type utilizes a combustion oven operating inexcess of 800C (1472F) to assure the combustion of gaseswithin the natural or flare gas compositions being combusted asshown in Fig. 3.6.5 Burned Gas Sensor:6.5.1 The burned or combusted gas sensor must measure acharacteristic of the
34、 burned gas which is a function of thecombustion ratio and for which there is a critical combustionratio related to the stoichiometric ratio. A combustion chamberof the first type (Fig. 1) would have one sensor in the burnedgas and its output signal would constitute the desired measure-ment. In a co
35、mbustion chamber of the second type (Fig. 2)there would be a sensor in the burned gas from each burner.The difference between the two output signals would constitutethe desired measurement. In the third type (Fig. 3), the residualoxygen is measured and the resulting oxygen value is corre-lated to th
36、e CARI and Wobbe Index.6.5.2 There are several properties of the burned gas whichare related uniquely to the combustion ratio. A burned gassensor may be selected which provides a measure of any one ofthese, for example, either temperature or oxygen partial pres-sure.6.6 ElectronicsElectronics are us
37、ed to receive the signalsfrom the components described above to control the flow ofgases into the combustion chamber in response to the signalfrom the burned gas sensor and to provide a digital or analogoutput signal, or both, which is proportional to the heatingvalue of the gaseous fuel.6.7 Tempera
38、ture Stability and Operating EnvironmentThemethod is capable of operating over a range of temperatureslimited only by the specific apparatus used to realize themethod. It is desirable to equilibrate the air and fuel tempera-tures before the gases are measured. The electronics shouldTABLE 2 Continued
39、Compound CAS NumberPropanal 123-38-6C1 to C5 HydrocarbonsDescription Compound CAS NumberC1 Alkanes Methane 74-82-8C2 Alkanes Ethane 74-84-0C3 Alkanes Propane 74-98-6C4 Alkanesn-Butane 106-97-8Isobutane 75-28-5C5 Alkanesn-Pentane 109-66-02-Methylbutane 78-78-4Cyclopentane 287-92-3C2 Olefins Ethylene
40、74-85-1C2 Alkanes Acetylene 74-86-2C3 Olefins Propylene 115-07-1C4 Olefins 1-Butene 106-98-92-Butene 107-01-7Isobutene 115-11-7C5 Olefins 1-Pentene 109-67-1Cis-2-pentene 627-20-3Trans-2-pentene 646-04-82-Methyl-1-butene 563-46-23-Methyl-1-butene 563-45-12-Methyl-2-butene 513-35-9Cylcopentene 142-29-
41、0C3 Alkadienes Propadiene 463-49-0C4 Alkadienes 1,2-Butadiene 590-19-21,3-Butadiene 106-99-0C5 Alkadienes 1,2-Pentadiene 591-95-71-cis-3-Pentadiene 1574-41-01-trans-3- Pentadiene 2004-70-81,4-Pentadiene 591-93-52,3-Pentadiene 591-96-83-Methyl-1,2- butadiene 598-25-42-Methyl-1,3- butadiene 78-79-5Cyc
42、lopentadiene 542-92-7Heating Value RangeUnit Lower UpperBtu/ft383 2350AFlare Gas Heating Value range defined in Table 2 is derived from the Evaluationof the Efficiency of Industrial Flares: Flare Head Design and Gas CompositionEPA-600 /2-85-106 September 1985 Table 1-1. Agency Information Collection
43、Activities OMB Responses EPA ICR Number 2411.01; NSPS and NESHAP forPetroleum Refineries Sector Residual Risk and Technology; OMB Number2060-0657.FIG. 1 Gas Btu Transmitter (Functional Overview)FIG. 2 Stoichiometric Combustion ApparatusD4891 13 (2018)3FIG.3ResidualOxygenStoichiometricCombustionAppar
44、atusD4891 13 (2018)4also be stabilized against temperature changes and the burnedgas sensor should be insensitive to changes in the ambientconditions.7. Reagents and Materials7.1 Physical ContaminationThe air and gas must be freeof dust, liquid, water, liquid hydrocarbons, and other entrainedsolids.
45、 Foreign materials should be removed by a sample linefilter. To avoid any problems in the line from any liquidaccumulation, pitch the line to a low point and provide a dripleg.7.2 Chemical ContaminationThe air must be free ofcombustible compounds. The oxygen content and the absolutehumidity of the a
46、ir should be the same during measurement asduring calibration.8. Calibration and Standardization8.1 The calibration factor, F, and the constant, B,intheequation, C=FR+B, are determined through an initialcalibration, in which the critical combustion ratios of at leasttwo standard gases of known but d
47、ifferent heating values aremeasured using the procedure described in 9.1.8.2 The calibration factor, F, is routinely redetermined atregular intervals under field conditions using a calibration gasof known heating value. The constant, B, is not adjusted in theroutine calibrations. The interval betwee
48、n routine calibrationsmust be determined under the specific operating conditions,and is usually of the order of 24 h. Determination of Festablishes the amount of net oxygen per standard volume ofcombustion air. Variations in net oxygen constant can becaused by several factors, such as changes in abs
49、olute humidityor the presence of contaminants in the air supply.8.3 The calibration when utilizing multiple calibration gasesin which these standards are used for calibrating the low, andin some calorimeter configurations the mid point of theexpected measurement range for Heating Value, Specific Grav-ity (Relative Density; where Air = 1.0000). Refer to thecalorimeters manufactures manual for the proper calibrationprocedure. The interval between routine calibrations must bedetermined under the specific operating conditions, and canvary between 24
