DIN 51865-2-2000 Testing of gaseous fuels and other gases - Determination of mercury content - Part 2 Combustion using the modified Lingener method Atomic absorption spectrometry (.pdf

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1、Ref. No. DIN 51865-2 : 2000-10English price group 06 Sales No. 010608.02DEUTSCHE NORM October 200051865-2Continued on pages 2 to 4. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,h

2、as the exclusive right of sale for German Standards (DIN-Normen).Determining the mercury content of gaseousfuels by the modified Lingener combustionmethod and atomic absorption spectrometryTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the aut

3、horitative text.ICS 75.160.30Prfung von gasfrmigen Brennstoffen und sonstigen Gasen Bestimmung des Quecksilbergehaltes Teil 2: Verbrennung nach dem modifizierten Lingener-Verfahren; Atomabsorptionsspektrometrie (AAS)In keeping with current practice in standards published by the International Organiz

4、ation for Standardization(ISO), a comma has been used throughout as the decimal marker.ForewordThis standard has been prepared by Technical Committee Anforderungen an und Prfung von Brenngasenof the Normenausschuss Materialprfung (Materials Testing Standards Committee).1 ScopeThe method specified in

5、 this standard serves to determine the mercury content of gaseous fuels in order tocheck fuel quality, monitor gas purification plants and assess the corrosive and toxic properties of suchfuels.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other pub

6、lications. Thesenormative references are cited at the appropriate places in the text, and the titles of the publications arelisted below. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this standard only when incorporated in it by amendment or revisi

7、on. For undated references, thelatest edition of the publication referred to applies.DIN 12463 Bottles with standard ground joint, 200 mm in height, for laboratory useDIN 12596 Drechsel gas washing bottles for laboratory useDIN 12778 Laboratory thermometers with 1 C and 2 C scale intervalsDIN 38406-

8、12 German standard methods for the examination of water, waste water and sludge Cations (group E) Determination of mercury (E 12)DIN 51400-4 Determination of total sulfur content of petroleum products by the Lingener combus-tion methodDIN 51851 Determining the reduced gas volume of gaseous fuels and

9、 other gasesDIN 51853 Sampling of gaseous fuelsDIN EN ISO 6326-5 Natural gas Determination of sulfur compounds Part 5: Lingener combustionmethod (ISO 6326-5 : 1989)Page 2DIN 51865-2 : 2000-103 PrincipleA known volume of gas is burnt at a slightly positive pressure in a sealed combustion apparatus wi

10、th air thathas been purified over activated carbon. The mercury is absorbed in 5 % (m/m) nitric acid and, to ensurequantitative absorption, the gas to be examined is passed over 1,1,1-trichloroethane prior to combustion. Themercury content is then determined by flameless atomic absorption spectromet

11、ry.4 DesignationDesignation of the method specified in this standard (02) of determining the mercury content (Hg) by combus-tion using the modified Lingener combustion method (L), followed by detection by atomic absorptionspectrometry (AAS):Test DIN 51865 02 Hg L AAS5 Apparatus and reagents5.1 Appar

12、atusIn addition to standard laboratory equipment, the following shall be used.a) Filter, filled with iodide-containing activated carbon (9) (see figure 1).b) Polyvinyl acetate hose connections.c) Flameless AAS spectrometer, equipped with mercury attachment (cold vapour technique).d) Lingener combust

13、ion apparatus, as shown in figure 1 (cf. figure 1 in DIN EN ISO 6326-5).11 Combustion vessel12 Pressure-equalizing vessel13 Capillary flowmeter for flow rates of 10 l/min to 30 l/min14 Pressure gauge15 Thermal mass flow regulator, having a pressure gauge and a thermometer for temperatures up to50 C

14、(e.g. DIN 12778 LST-50/50 thermometer). Other devices may be used if they have been shownto give the same result.16 Condensate trap17 Vacuum pump, having a suction capacity of about 25 l/min18 1,1,1-trichloroethane saturator19 Filter, filled with iodide-containing activated carbon10 Gas11 AirFigure

15、1: Modified Lingener combustion apparatusPage 3DIN 51865-2 : 2000-10e) Drechsel gas washing bottle, with NS 29 ground conical joint (as in DIN 12596).f) Gas washing bottle base, with NS 29 ground conical socket (as in DIN 12463).5.2 Reagents5.2.1 GeneralOnly analytical grade reagents or those partic

16、ularly low in mercury and twice-distilled water or water of equiva-lent purity shall be used. The mercury content of the water and the reagents shall be negligible compared withthe lowest concentration to be determined.5.2.2 Absorption solution, to be prepared by diluting 65 % (m/m) nitric acid, HNO

17、3, of density 1,40g/ml, withwater to a concentration of 5 % (m/m).5.2.2.1 1,1,1-trichloroethane, C2H3Cl3.5.2.3 Reduction solution, to be prepared by dissolving 2 g of sodium borohydride, NaBH4, in 100 ml of waterand 5 ml of 20 % (m/m) sodium hydroxide solution, NaOH, adding 500 mg to 1000 mg of calc

18、ium hydroxide,Ca(OH)2, and heating to 60 C to 70 C. Cool and filter the solution, then make it up to 200 ml with water. Ifrefrigerated, the solution will be stable for about ten days.5.2.4 CalibrationUse the reagents specified in DIN 38406-12 for calibration.6 Combustion6.1 PreparationFill the satur

19、ator (8) with 1,1,1,-trichloroethane to just below the gas inlet tube and use the vacuum pump (7)to draw air purified over activated carbon through the apparatus at a flow rate of about 20 l/min. Remove theburner and pour sufficient absorption solution into the receiver for the extremely effervescen

20、t solution to flowcontinuously round the flame tube up to the height of the burner nostril during combustion. After the coolingwater has been turned on, the combustion apparatus is ready for use.6.2 SamplingCollect samples under reduced pressure (less than 50 mbar) using the sampling procedure speci

21、fied insubclause 5.1.2 of DIN 51853, November 1995 edition.Open the shut-off valve for a short time to blow any deposits or contaminants out of the sampling valve, butensure that excessive blasting does not cause the valve to ice up as a result of the Joule-Thomson effect duringthis procedure. Use a

22、 heated pressure regulator to let down the pressurized test gas to a few millibars and feedit via a 6 mm diameter stainless steel tube or hoses that are as short as possible to the thermal mass flowregulator (5).As a rule, the sample volume will be 120 l, but for mercury concentrations of less than

23、1 mg/m3, it may beincreased to 200 l.Measure the volume using a mass flowmeter, a dry gas volumeter or a flow capillary. Before use, calibrate thevolumeter with a gas of composition similar to that of the gas to be examined.6.3 ProcedureWith an inlet pressure reading of not more than 10 mbar on the

24、pressure gauge (4), ignite the gas issuing fromthe removed burner. Carefully lower the burner with the flame directed downwards into the flame tube and notethe initial reading of the thermal mass flow regulator, VA. Read the gas temperature, tG, and the gauge pressure,pG, in the gas volumeter at equ

25、al intervals, but at least at the beginning and end of sampling. At the same timeread the air pressure, pL, on the pressure gauge and adjust the volumetric air flow and the cooling water flowrate if necessary. Keep the exhaust gas temperature at between 50 C and 60 C. As soon as the requiredvolume o

26、f gas has been burnt, shut off the gas supply and then switch off the vacuum pump. Drain theabsorption solution into a suitable glass vessel, rinse the receiver with water and make up to the total volume,V1. Also note the final reading of the thermal mass flow regulator, VE.7 AnalysisAfter reduction

27、 with the reduction solution (as in subclause 5.2.3), carry out an AAS analysis as specified inDIN 38406-12 using a spectrometer with mercury attachment.8 EvaluationCalculate the reduced volume of gas (cf. DIN 51851), VG, in m3, using equation (1):VG= 25,013115,27315,273)()()(+GGLAEtppVV(1)Page 4DIN

28、 51865-2 : 2000-10whereVEis the final reading of the thermal mass flow regulator, in m3;VAis the initial reading of the thermal mass flow regulator, in m3;pLis the air pressure, in mbar;pGis the gauge pressure in the thermal mass flow regulator (averaged over the sampling period), in mbar;tGis the t

29、emperature in the thermal mass flow regulator (averaged over the sampling period), in C.Calculate the mercury content, b(Hg), in mg/m3, under standard conditions, using equation (2)b(Hg) = GVVVm21(2)wherem is the mass of mercury in the sample solution analysed, in mg;V1is the volume of the entire sa

30、mple solution, in ml;V2is the volume of the sample solution analysed, in ml;VGis the gas volume, in m3.9 Test reportThe test report shall refer to this standard and include the following details:a) type and designation of sample;b) date of sampling;c) number of samples;d) mercury content, expressed in mg/m3(mean and standard deviation);e) date of testing.