1、ICS 75.160.10Prfung fester Brennstoffe Bestimmung des Gehaltes an flchtigenBestandteilenIn 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 51720 : 2001-03English price
2、 group 07 Sales No. 010701.03DEUTSCHE NORM March 200151720Continued on pages 2 to 6. 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 Stand
3、ards (DIN-Normen).Determining the volatile matter content ofsolid fuelsTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.SupersedesJune 1978 edition.ForewordThis standard has been prepared by Technical Committee Prfung fest
4、er Brennstoffe of the Normenaus-schuss Materialprfung (Materials Testing Standards Committee). It is based on ISO 562 with which itconforms in substance.AmendmentsThis standard differs from the June 1978 edition, in that the scope has been extended to cover brown coaland lignite. Furthermore, it has
5、 been completely revised and harmonized with ISO 562.Previous editionsDIN DVM 3725: 1933-03; DIN DVM 3725 = DIN 53725: 1939-11; DIN 51720: 1950-08, 1957-08, 1967-10,1978-06.IntroductionThe volatile matter content is determined as the loss in mass, excluding the loss due to moisture, when thesolid fu
6、els referred to in clause 1 are heated under specified conditions in the absence of air. Since the testmethod is empirical, reproducible results can only be obtained if the rate of rise in temperature, the finaltemperature and the total duration of the test are in accordance with this standard. It i
7、s also essential toprevent oxidation due to contact with oxygen during the analysis by ensuring that the lid is particularly wellfitted to the crucible. The moisture content of the sample is determined so that an appropriate correctioncan be made and the result can be converted to other reference co
8、nditions.It should be noted that mineral constituents in the sample may also lose mass during the test, the extent ofthe mass loss depending on both the nature and the quantity of mineral matter present.Test equipment and procedure are designed so that more than one analysis can be made in the furna
9、ce atthe same time.Page 2DIN 51720 : 2001-03All dimensions are in millimetres.1 ScopeThe method specified in this standard serves to determine the volatile matter in hard coal, brown coal andlignite, in coke produced from these fuels and in lumpwood charcoal and lumpwood charcoal briquettes.NOTE: If
10、 this standard is used to classify solid fuel on the basis of samples obtained directly from deposits, itshould be borne in mind that an ash content markedly greater than 10 % (m/m) may falsify the result.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions fro
11、m other publications. These norma-tive references are cited at the 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 amendm
12、ent or revision. For undated references, the latest edition ofthe publication referred to applies.DIN 51700 General information and survey of methods of testing solid fuelsDIN 51701-3 Sampling of solid fuels Sample preparationDIN 51718 Determining of the moisture content of solid fuelsDIN 51726 Dete
13、rmining the carbonate/carbon dioxide content of solid fuelsISO 562 : 1998 Hard coal and coke Determination of volatile matterISO 5725-1 : 1994 Accuracy (trueness and precision) of measurement methods and results Part 1: Generalprinciples and definitions3 ConceptVolatile matterDecomposition products
14、of solid fuel of organic origin that escape when the fuel is heated under specifiedconditions to a temperature of 900 C in the absence of air.4 PrincipleA moist fuel sample is heated for seven minutes at 900 C in the absence of air and the volatile matter contentis calculated from the loss in mass o
15、f the sample corrected for the loss in mass due to the moisture that escapes.5 ApparatusThe following equipment shall be used.5.1 Electrically heated furnace, capable of maintaining a temperature of (900 t 5) C. It may be of the stop-end type or fitted with a flue having a diameter of about 25 mm an
16、d a length of about 150 mm (see figure 1).NOTE: In the case of furnaces fitted with flues, it is important that the furnace door seals well. The flue shouldnot project far out of the furnace and should be fitted with a butterfly valve to restrict the air flow throughthe furnace.The heat capacity of
17、the furnace shall be such that the initial temperature of 900 C is restored within fourminutes after a cold crucible and its stand have been inserted. The temperature shall be measured using athermocouple, as described in subclause 5.2.The furnace shall be designed either for multiple analyses with
18、a number of crucibles in one stand or for singleanalyses (i.e. using one crucible in a stand). In both cases, the zone of uniform temperature should be at least160 mm 100 mm.The crucible stand shall be placed in the zone of uniform temperature, its position being the same for allanalyses. The test t
19、emperature of 900 C shall be maintained as vigorously as possible (the tolerance of t5Cincluding errors in temperature measurement and errors due to the temperature distribution being nonuniform).Page 3DIN 51720 : 2001-03Key1 Chamber (width: 200 mm)2 Flue3 Valve4 Thermocouple (sheathed)5 Heating sys
20、tem6 Zone of uniform temperature7 Thermocouple (not sheathed)Figure 1: Furnace (example)5.2 Unsheathed thermocouple, having a diameter of not more than 1 mm. It shall be long enough, whenintroduced through the front or rear of the furnace, to measure the temperature underneath each crucible in thezo
21、ne of uniform temperature with the junction at a point midway between the base of the crucible in its standand the floor of the furnace. If the stand holds more than one crucible, the temperature underneath each crucibleshall be checked in the same way.A sheathed thermocouple may also be permanently
22、 installed in the furnace (see figure 1) with its junction in thecentre of the zone of uniform temperature, with the readings being compared at regular intervals with those ofthe unsheathed thermocouple (which is thus only inserted when necessary).NOTE: The temperature/electromotive force relationsh
23、ip of a thermocouple gradually changes when it is ex-posed to high temperatures for prolonged periods.5.3 Cylindrical quartz crucible, having a well-fitting lid of the same material, the total mass of crucible andlid being between 10 g and 14 g and the dimensions being as shown in figure 2. Since th
24、e fit of the lid cruciallyaffects the analysis, it shall be selected so that the horizontal clearance between crucible and lid does notexceed 0,5 mm. After selection, the crucible and lid shall be ground together to give smooth surfaces and thenprovided with a common distinguishing mark.NOTE: If mul
25、tiple analyses are carried out simultaneously on coals which undergo considerable swelling, it maybe necessary to use larger crucibles, whose depth may be up to 45 mm without affecting the result of theanalysis, provided the specified rate of temperature recovery is maintained.Page 4DIN 51720 : 2001
26、-03Figure 2: Crucible5.4 Crucible stand, for placing the crucible in the furnace, designed so that the required rate of heating canbe achieved. Stands for single analyses may consist, for example, of a ring made of heat-resistant steel wireas shown in figure 3, with a ceramic disc 25 mm in diameter
27、and 2 mm thick, resting on the inner projectionsof its legs, while those for multiple analyses shall consist, for example, of a stand made of heat-resistant steelwire of suitable size as shown in figure 4 having two ceramic plates 2 mm thick.Key1 Handle2 RingaThree legs spaced 120 apartFigure 3: Cru
28、cible stand for single analysesPage 5DIN 51720 : 2001-03Key1 Ceramic platesFigure 4: Crucible stand for multiple analyses5.5 Analytical balance, capable of being read to an accuracy of 0,1 mg.6 Sample preparationThe sample shall be dried in air, prepared as specified in DIN 51701-3 and ground to a p
29、article size notexceeding 0,2 mm. It shall be well mixed and in moisture equilibrium with the laboratory atmosphere. Themoisture content shall be determined as specified in DIN 51718 in parallel with the volatile matter determinationso that the appropriate correction can be made and the result conve
30、rted to other reference conditions.7 Procedure7.1 Furnace temperature checkAdjust the temperature in the zone of uniform temperature (see subclause 5.1) to (900 t 5) C either with onestand holding one crucible and lid or with a stand holding the requisite number of crucibles and lids using acorrectl
31、y located thermocouple (as in subclause 5.2). Check that the temperature under each crucible is withinthe specified tolerance when measured at the same height.NOTE: Although the temperature(s) should be checked before the analysis/analyses is/are started, a dailytemperature check will be adequate if
32、 several analyses are made in series in the course of one day. Thetemperature recovery after inserting a cold crucible stand shall be checked in the same way (see subclause 5.1).7.2 Volatile matter determinationHeat the crucible(s) and lid(s) in the appropriate stand in the furnace at (900 t 5) C fo
33、r seven minutes, thenremove the crucible(s) and allow it (them) to cool to ambient temperature on a metal plate.As soon as it (they) is (are) at ambient temperature, weigh the crucible(s) and lid(s), then weigh (1 t 0,1) mg ofsample to an accuracy of 0,1 mg into the crucible or each of the crucibles
34、. Replace the lid(s) and tap eachcrucible on a clean hard surface until the sample forms a layer of uniform thickness on the bottom of the crucible.In the case of coke samples, remove the lid from the charged crucible, add two to four drops of cyclohexaneand replace the lid(s) again.NOTE 1: Adding c
35、yclohexane prevents oxidation of the coke, but not the absorption of gases (e.g. nitrogen).Place the charged crucible(s) in a cold stand and insert it (them) in the furnace. Close the door and leave it (them)for seven minutes (t five seconds). After allowing it (them) to cool to ambient temperature
36、in the same way asthe empty crucible(s), reweigh it (them) to an accuracy of 0,1 mg.NOTE 2: An identical treatment before and after the analysis minimizes the effect of any water adsorbed on thesurface of the crucible(s), while rapid cooling reduces absorption by the coal or coke residue.In the case
37、 of multiple analyses, any empty positions in the stand shall be filled with empty crucibles.Page 6DIN 51720 : 2001-038 Expression of resultsCalculate the volatile matter in the sample, w(Fan), as a percentage by mass, using the following equation:()()MmmmmFw =1232100 .anwherem1is the mass of the em
38、pty crucible and lid, in g;m2is the mass of the crucible, sample and lid before heating, in g;m3is the mass of the crucible, sample and lid after heating, in g;M is the moisture content determined as specified in DIN 51718, as a percentage by mass.The results shall be reported to the nearest 0,1 % a
39、s the mean of duplicate determinations. The analysesdescribed in this standard relate to moist sample material and shall be converted to other reference conditionsas described in DIN 51700.9 PrecisionUnder the conditions specified in this standard, the repeatability limit, r, and the reproducibility
40、 limit, R,determined as specified in ISO 5725-1, as percentages by mass, and converted in each case to the samemoisture content, are as shown in table 1.Table 1: PrecisionVolatile matter Repeatability limit Reproducibility limitHard coal having a volatile matter 0,3 % (absolute) 0,5 % (absolute)cont
41、ent of less than 10 % (m/m)Hard coal having a volatile matter 3 % of mean 0,5 % (absolute) or 4 % of mean,content of 10 % (m/m) or more whichever is the greaterCoke 0,2 % (absolute) 0,3 % (absolute)Brown coal 3 % of mean 0,5 % (absolute) or 4 % of mean,whichever is the greater10 Test reportThe test
42、report shall refer to this standard and include the following details as a minimum:a) description of sample;b) method used;c) date of analysis;d) result as the mean from duplicate analyses, together with the reference condition;e) any unusual observations made during the analysis.Explanatory notesTh
43、e volatile substances in industrial coke produced at temperatures above 1000 C that escape from a sampleroasted in the absence of air at 900 C (as specified in this standard) contain some carbon monoxide and carbondioxide formed by reaction of absorbed oxygen with substances in the coke. Determining
44、 the volatile mattercontent can therefore only provide an indication of the degree of degassing.The substances that escape also contain moisture and products due to the decomposition of inorganic impu-rities in the coal (e.g. carbon dioxide originating from carbonates and water of hydration due to c
45、lay minerals).Moreover, reactions may occur between fuel constituents, inorganic impurities and decomposition products.Whereas the moisture has to be taken into account in determining the volatile matter content, the decompo-sition and reaction products of the minerals may be neglected if their quantities are negligible.If the carbonate content is appreciable, it is advisable to determine the amount of carbon dioxide it producesas specified in DIN 51726 and to subtract the amount from the total loss.Other relevant standardDIN 51719 Determination of ash in solid mineral fuels
