1、Designation: D4891 89 (Reapproved 2006)D4891 13Standard 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 ado
2、ption 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 the heating value of natur
3、al gases and similar gaseous mixtures within therange of composition shown in Table 1., and Table 2 that covers flare components but is not intended to limit the components tobe measured in flare gases.1.2 This standard involves combustible gases. It is not the purpose of this standard to address th
4、e safety concerns, if any,associated with their use. It is the responsibility of the user of this standard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1826 Test Method for Calor
5、ific (Heating) Value of Gases in Natural Gas Range by Continuous Recording CalorimeterE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 EPA Standard:3EPA-600 /2-85-106 Evaluation of the Efficiency of Industrial Flares: Flare Head Design and Gas Comp
6、osition3. Terminology3.1 All of the terms defined in Test Method D1826 are included by reference.3.2 Definitions of Terms Specific to This Standard:3.2.1 combustion ratioratio, nthe ratio of combustion air to gaseous fuel.3.2.2 stoichiometric ratiothe combustion ratio when the quantity of combustion
7、 air is just sufficient to convert all of thecombustibles in the fuel to water and carbon dioxide.3.2.2 burned gas parameterparameter, na property of the burned gas after combustion which is a function of thecombustion ratio.3.2.3 critical combustion ratioratio, n for a specific burned gas parameter
8、, the combustion ratio at which a plot of burnedgas parameter versus combustion ratio has either maximum value or maximum slope.3.2.4 combustion air requirement index (CARI), nis the amount of air required for complete combustion of the gas beingmeasured and can be used to index against other measur
9、ed values such as the Wobbe Index or Heating Value.3.2.5 stoichiometric ratio, nthe combustion ratio when the quantity of combustion air is just sufficient to convert all of thecombustibles in the fuel to water and carbon dioxide.4. Summary of Test Method4.1 Air is mixed with the gaseous fuel to be
10、tested. The mixture is burned and the air-fuel ratio is adjusted so that essentiallya stoichiometric proportion of air is present. More exactly, the adjustment is made so that the air-fuel ratio is in a constant1 This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and i
11、s the direct responsibility of Subcommittee D03.03 on Determination ofHeating Value and Relative Density of Gaseous Fuels.Current edition approved June 1, 2006May 1, 2013. Published June 2006May 2013. Originally approved in 1989. Last previous edition approved in 2001 asD489189 (2001). DOI: 10.1520/
12、D4891-89R06.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from United States Environmental Prot
13、ection Agency (EPA), Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004, http:/www.epa.gov.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be tec
14、hnically 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 considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO
15、 Box C700, West Conshohocken, PA 19428-2959. United States1TABLE 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
16、.01 to 10n-pentane 0.01 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 disu
17、lfide 75-15-0Chlorobenzene 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 109-66-0Styren
18、e 100-42-5Tetrachloroethene 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 120-12-7Benzid
19、ine1 92-87-5Benzaanthracene 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 192-65-4
20、3,3- Dimethoxybenzidine 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-
21、52-Methylnaphthalene 91-57-6Naphthalene 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 132proportion to the stoichiometric ratio whichthat is a relative
22、measure of the heating value. To set this ratio, a characteristic propertyof the burned gas is measured, such as temperature or oxygen concentration.5. Significance and Use5.1 This test method provides an accurate and reliable procedure to measure the total heating value of a fuel gas, on a continuo
23、usbasis, which is used for regulatory compliance, custody transfer, and process control.5.2 Some instruments which conform to the requirements set forth in this test method can have response times on the order of1 min or less and can be used for on-line measurement and control.5.3 The method is sens
24、itive to the presence of oxygen and nonparaffin fuels. For components not listed and composition rangesthat fall outside those in Table 1 and Table 2, modifications in the method and changes to the calibration gas or gasses being usedmay be required to obtain correct results.6. Apparatus6.1 A suitab
25、le apparatus for carrying out the stoichiometric combustion method will have at least the following fourcomponents: flow meter or regulator, or both; combustion chamber; burned gas sensor; and electronics. The requirement for eachof these components is discussed below. The detailed design of each of
26、 these components can vary. TwoThree different apparatusare shown in Fig. 1 and, Fig. 2 and Fig. 23. In each figure the equivalent of the four necessary components are enclosed in dashedlines.TABLE 2 ContinuedCompound CAS NumberPropanal 123-38-6C1 to C5 HydrocarbonsDescription Compound CAS NumberC1
27、Alkanes Methane 74-82-8C2 Alkanes Ethane 74-84-0C3 Alkanes Propane 74-98-6C4 Alkanes n-Butane 106-97-8Isobutane 75-28-5C5 Alkanesn-Pentane 109-66-02-Methylbutane 78-78-4Cyclopentane 287-92-3C2 Olefins Ethylene 74-85-1C2 Alkanes Acetylene 74-86-2C3 Olefins Propylene 115-07-1C4 Olefins 1-Butene 106-98
28、-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 142-29-0C3 Alkadienes Propadiene 463-49-0C4 Alkadienes 1,2-Butadiene 590-19-21,3-Butadiene 106-99
29、-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 78-79-5Cyclopentadiene 542-92-7Heating Value RangeUnit Lower UpperBtu/ft3 83 2350AFlare Gas Heating
30、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 CollectionActivities OMB Responses EPA ICR Number 2411.01; NSPS and NESHAP forPetroleum Refineries
31、Sector Residual Risk and Technology; OMB Number2060-0657.D4891 1336.2 OverviewAir and fuel enter the apparatus and the flow of each is measured. Alternatively, only one gas flow need bemeasured if the flow of the other is kept the same during measurement and calibration. This is illustrated in Fig.
32、2. Next there isa combustion chamber in which the air and fuel are mixed and burned. This can be as simple as a bunsen or meeker burner, butprecautions should be taken that subsequent measurements of burned gas characteristics are not influenced by ambient conditions.Finally, there is a sensor in th
33、e burned gas which measures a property of this gas that is sensitive to the combustion ratio and hasa unique feature at the stoichiometric ratio. Two such properties are temperature and oxygen concentrations, and either can bemeasured.6.3 Flow Meter and/or Regulatoror Regulator, or bothThe flow meas
34、urement part of the apparatus should have an accuracyand precision of the order of 0.1 %. Likewise, if the flow is to be kept constant, the flow regulator should maintain this constantvalue within 0.1 %. The meter or regulator for natural gas must maintain this precision and accuracy over the densit
35、y and viscosityranges consistent with the composition range in Table 1 or Table 2.6.4 Combustion Chamber:6.4.1 There are two different types of combustion chambers that may be used. In the first type the air and fuel are mixed andburned in a single burner. The apparatus shown in Fig. 1 has this type
36、 of combustion chamber.6.4.2 In the second type of combustion chamber, the air and fuel are each divided into two streams, and combustion takes placesimultaneously in two burners. The division of air flow must be such that the proportion of air going to each burner always remainsthe same. Likewise t
37、he division of fuel flow must always remain the same even through fuel composition changes. Anotherrequirement is that the flow divisions be such that one burner has a mixture with a slightly higher combustion ratio than the other.The apparatus shown in Fig. 2 has this type of combustion chamber.6.4
38、.3 A third type utilizes a combustion oven operating in excess of 800C (1472F) to assure the combustion of gases withinthe natural or flare gas compositions being combusted as shown in Fig. 3.6.5 Burned Gas Sensor:6.5.1 The burned or combusted gas sensor must measure a characteristic of the burned g
39、as which is a function of the combustionratio and for which there is a critical combustion ratio related to the stoichiometric ratio. A combustion chamber of the first typeFIG. 1 Gas Btu Transmitter (Functional Overview)FIG. 2 Stoichiometric Combustion ApparatusD4891 134(Fig. 1) would have one senso
40、r in the burned gas and its output signal would constitute the desired measurement. In a combustionchamber of the second type (Fig. 2) there would be a sensor in the burned gas from each burner. The difference between the twooutput signals would constitute the desired measurement. In the third type
41、(Fig. 3), the residual oxygen is measured and theresulting oxygen value is correlated to the CARI and Wobbe Index.6.5.2 There are several properties of the burned gas which are related uniquely to the combustion ratio. A burned gas sensormay be selected which provides a measure of any one of these,
42、for example, either temperature or oxygen partial pressure.6.6 ElectronicsElectronics are used to receive the signals from the components described above to control the flow of gasesinto the combustion chamber in response to the signal from the burned gas sensor and to provide a digital or analog ou
43、tput signal,or both, which is proportional to the heating value of the gaseous fuel.6.7 Temperature Stability and Operating EnvironmentThe method is capable of operating over a range of temperatures limitedonly by the specific apparatus used to realize the method. It is desirable to equilibrate the
44、air and fuel temperatures before the gasesare measured. The electronics should also be stabilized against temperature changes and the burned gas sensor should beinsensitive to changes in the ambient conditions.7. Reagents and Materials7.1 Physical ContaminationThe air and gas must be free of dust, l
45、iquid, water, liquid hydrocarbons, and other entrained solids.Foreign materials should be removed by a sample line filter. To avoid any problems in the line from any liquid accumulation, pitchthe line to a low point and provide a drip leg.7.2 Chemical ContaminationThe air must be free of combustible
46、 compounds. The oxygen content and the absolute humidityof the air should be the same during measurement as during calibration.8. Calibration and Standardization8.1 The calibration factor, F, and the constant, B, in the equation, C = FR + B, are determined through an initial calibration,in which the
47、 critical combustion ratios of at least two standard gases of known but different heating values are measured using theprocedure described in 9.1.8.2 The calibration factor, F, is routinely redetermined at regular intervals under field conditions using a calibration gas ofknown heating value. The co
48、nstant, B, is not adjusted in the routine calibrations. The interval between routine calibrations mustbe determined under the specific operating conditions, and is usually of the order of 24 h. Determination of F establishes theamount of net oxygen per standard volume of combustion air. Variations i
49、n net oxygen constant can be caused by several factors,such as changes in absolute humidity or the presence of contaminants in the air supply.FIG. 3 Residual Oxygen Stoichiometric Combustion ApparatusD4891 1358.3 The calibration when utilizing multiple calibration gases in which these standards are used for calibrating the low, and insome calorimeter configurations the mid point of the expected measurement range for Heating Value, Specific Gravity (RelativeDensity; where Air = 1.0000). Refer to the calorimeters manufactures manual for the
