1、ICS 75.160.10Prfung fester Brennstoffe Bestimmung des Wassergehaltesund der AnalysenfeuchtigkeitIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.Ref. No. DIN 51718 : 2002-06Engli
2、sh price group 06 Sales No. 000601.03DEUTSCHE NORM June 200251718 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,has the exclusive right of sale for German Standards (DIN-Normen).Tr
3、anslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.Determining the moisture content of solid fuelsContinued on pages 2 to 5.ForewordThis standard has been prepared by Technical Committee Prfung fester Brennstoffe of the Normen
4、-ausschuss Materialprfung (Materials Testing Standards Committee).AmendmentsThis standard differs from the September 1995 edition as follows:a) The drying temperature for determining the moisture content of brown coal has been specified.b) Requirements relating to the test report have been included.
5、c) The standard has been editorially revised and brought in line with current practice in the presentationof standards.Previous editionsDIN DVM 3721, 1933-03; DIN DVM 3721 = DIN 53721, 1934-05; DIN 51718, 1950X-08, 1978-01, 1995-09.1 ScopeThis standard specifies methods for the routine determination
6、 of the moisture content of solid fuels, suchas hard coal, brown coal, coke, briquettes, peat and charcoal. As an important quality characteristic of thesefuels, knowledge of the moisture content is essential for converting test results to reference conditions(cf. DIN 51700).The three methods descri
7、bed in this standard for determining the total moisture content of a laboratorysample may yield results that differ systematically from one another, the differences depending essentiallyon the state of carbonification.To achieve agreement between interlaboratory results, it is essential that the sam
8、e methods be used andthe test conditions specified in this standard be adhered to.SupersedesSeptember 1995 edition.Page 2DIN 51718 : 2002-062 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive references are cited at th
9、e appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated references, the latest edition ofthe
10、 publication referred to applies.DIN 12420 Distillation receiver for water determination apparatus for laboratory useDIN 12576 Liebig/West condensers with conical ground joint for laboratory useDIN 12605 Weighing bottles for laboratory useDIN 51700 General information and survey of methods of testin
11、g solid fuelsDIN 51701-2 Sampling of solid fuels ProcedureDIN 51701-3 Sampling of solid fuels Sample preparationDIN EN ISO 4259 Petroleum products Determination and application of precision data relating to methodsof test (ISO 4259 : 1992 + Corr 1 : 1993)ISO 4797 : 1981 Laboratory glassware Flasks w
12、ith conical ground joints3 Concepts3.1 Nominal moisture contentFor the purposes of this standard, the moisture content of a laboratory sample of the fuel, expressed as apercentage by mass of the hydrated fuel. It includes only the water of hydration that escapes from the mineralsubstances under the
13、conditions specified in this standard, all the other moisture being considered by definitionas part of the anhydrous substance.3.2 Surface moisture contentMoisture that adheres to a sample and evaporates at 30 C in air. It depends on the relative humidity of the airused for drying. Fuel dried in air
14、 is referred to as air-dry.3.3 Air-dry moisture contentThe moisture content of an air-dried sample that has been reduced to a particle size of less than 1 mm.3.4 Moisture content under test conditionsThe moisture content of a sample as determined under the ambient conditions at the time of the analy
15、sis.3.5 Constant massThe mass deemed to have been reached if the decrease in mass after drying for a further 30 minutes is lessthan 0,05%.4 Symbols, quantities, and unitsSymbol Quantity UnitmEInitial sample mass gmRFinal sample mass gV Volume of water ml or gFA Moisture content under test conditions
16、 %FG Surface moisture content %FH Air-dry moisture content %W Nominal moisture content %Page 3DIN 51718 : 2002-065 DesignationDesignation of method A specified in this standard for determining the moisture content of solid fuels:Method DIN 51718 A6 Principle6.1 Method A (two-stage method; reference
17、method for hard coal, excluding anthracite)The surface moisture content of a laboratory sample is determined by drying it to constant mass at 30 C in airat a relative humidity of 50% to 70%. The air-dry moisture content of the air-dried sample is determined byreducing it to a particle size of less t
18、han 1 mm and drying an aliquot of it to constant mass at (106 t 2) C ina stream of nitrogen.NOTE: If systematic examinations have shown the moisture content of test samples to be equal to the air-dry moisture content, the former may be used to calculate the nominal moisture content. It is essential
19、toensure that any change in moisture content during the size reduction is negligible and that the moisturecontent of the test sample is determined immediately after the surface moisture content of the laboratorysample.6.2 Method B (single-stage method; reference method for coke and anthracite)A labo
20、ratory sample is dried to constant mass at (106 t 2) C in a stream of air.6.3 Method C (distillation method: reference method for brown coal, peat and charcoal)The moisture expelled from a fuel sample by distillation with xylene and condensed is determined volumetri-cally.7 Apparatus and reagentsThe
21、 following equipment and reagents are required for methods A and B.a) Drying dishes, of stainless material, measuring about 300 mm 400 mm 30 mm.b) Balance, capable of being read to an accuracy of 0,1 g.c) Balance, capable of being read to an accuracy of 0,1 mg.d) Oven, with exhaust.e) Oven, with nit
22、rogen flushing facility.f) Squat weighing bottle, with ground lid (e.g. as in DIN 12605).g) Tall weighing bottle, with ground lid (e.g. as in DIN 12605).h) Nitrogen, with a purity of not less than 99,5%.The following equipment and reagents are required for method C.a) Short narrow neck, round bottom
23、 flask, of nominal capacity 500 ml (e.g. as in ISO 4797).b) Balance, capable of being read to an accuracy of 0,01 g.c) Reflux condenser or descending condenser, 300 mm to 400 mm long (e.g. DIN 12576-L 400-29 con-denser).d) DIN 12420 distillation receiver.e) Heating jacket, or similar apparatus.f) Te
24、chnical grade pure xylene, saturated with water.8 Sampling and sample preparationSampling and sample preparation shall be performed as specified in DIN 51701-2 and DIN 51701-3.9 Procedure and evaluation9.1 GeneralSince sampling and sample preparation involve many operations (collection, mixing, divi
25、sion, size reduction,storage), the moisture content of the laboratory sample may be expected to differ from the true moisture contentof the test sample. Moisture losses can only be minimized by following the procedures described in DIN 51701-2and DIN 51701-3.Page 4DIN 51718 : 2002-069.2 Method A9.2.
26、1 Surface moisture contentSpread the laboratory sample (weighing not less than 1 000 g) evenly over a drying dish, weigh it to an accuracyof 0,1 g and dry it to constant mass at (30 t 2) C in an oven. If necessary, distribute the sample over severaldishes.Calculate the surface moisture content, FG,
27、as a percentage by mass, using the following equation:mE mRFG = 100 (1)mE9.2.2 Air-dry moisture contentAfter reducing the air-dried sample material to a particle size of less than 1 mm, weigh an aliquot (about 25 g)of it to an accuracy of 0,1 g into a squat weighing bottle (having a diameter of abou
28、t 80 mm) and dry it to constantmass at (106 t 2) C in a stream of nitrogen. Do not open the oven during this process. While continuing to flushthe oven with nitrogen, seal the weighing bottle with a tightly closing lid before removing it from the oven, andreweigh it after cooling.Calculate the air-d
29、ry moisture content, FH, as a percentage by mass, using the following equation:mE mRFH = 100 (2)mE9.2.3 Nominal moisture contentCalculate the nominal moisture content, W, as a percentage by mass, using the following equation:100 FGW = FG + FH (3)1009.3 Method BSpread about 2 000 g of a sample which
30、has been reduced to a particle size of less than 20 mm or, alternatively,1 000 g of a sample which has been reduced to a particle size of less than 10 mm, evenly over a drying dish andweigh it to an accuracy of 0,1 g, then dry it to constant mass in an oven at (106 t 2) C and reweigh it at atemperat
31、ure above 50 C.Calculate the nominal moisture content, W, as a percentage by mass, using the following equation:mE mRW = 100 (4)mE9.4 Method CWeigh, into a round bottom flask, enough sample material to an accuracy of 0,01 g to ensure that at least 1 mlof water will condense in the distillation recei
32、ver. As a guide, a 25 g sample will typically be required if themoisture content is high and 50 g sample if it is low. Cover the sample with 200 ml of xylene and shake well.Connect the flask containing this mixture to the distillation apparatus.After assembling the apparatus, distil the water/xylene
33、 mixture, collecting the vapour that condenses in thecondenser in the distillation receiver. Discontinue distillation when the condensed xylene is clear. Rinse anywater drops adhering to the wall of the condenser into the receiver with xylene. Determine the quantity of watercondensed with the xylene
34、 after cooling to ambient temperature. Any turbidity can be ignored.Calculate the nominal moisture content, W, as a percentage by mass, using the following equation:VW = 100 (5)mE9.5 Moisture content under test conditionsDetermine the moisture content of the sample and, for example, the ash content,
35、 the volatile matter and thecalorific value at the same time using the same sample. To do this, weigh about 1 g of the test sample to anaccuracy of 0,1 mg into a tall weighing bottle of diameter 25 mm and dry it to constant mass in an oven flushedwith nitrogen at (106 t 2) C and (135 t 2) C in the c
36、ase of hard and brown coal, respectively. Do not open theoven during this process and ensure that any effect due to residual oxygen is negligible. Cover the weighingbottle with a tightly sealing lid before removing it from the oven, and reweigh it after cooling.NOTE: The moisture content of coke and
37、 anthracite samples may be determined in a stream of air.Page 5DIN 51718 : 2002-06Calculate the moisture content under test conditions, FA, as a percentage by mass, using the followingequation:mE mRFA = 100 (6)mE10 Precision(cf. DIN EN ISO 4259)10.1 Repeatability limit(same operator, same equipment)
38、In parallel analyses carried out on aliquots of the same ground sample material, the individual values obtainedfor the air-dry moisture content and the moisture content under test will not differ by more than 0,2%.Under repeatability conditions, the individual values obtained for the nominal moistur
39、e content of brown coaldetermined by method C will not differ by more than 0,5%.10.2 Reproducibility limit(different operators, different equipment)Reproducibility limits for methods A and B cannot be given.11 Instrumental methodsAny instrumental methods used that permit a more rapid determination o
40、f the moisture content shall bedemonstrated to yield results that do not differ systematically from those of the above reference methods andthat the differences do not exceed those specified in clause 10.12 Test reportThe test report shall include the following information as a minimum:a) designation of method;b) a description of the sample material;c) result expressed as in clause 9;d) any unusual observations made during the analysis.
