ASTM D3302-2007ae1 Standard Test Method for Total Moisture in Coal《煤中总湿度的标准试验方法》.pdf

1、Designation: D 3302 07ae1Standard Test Method forTotal Moisture in Coal1This standard is issued under the fixed designation D 3302; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses

2、indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTE9.2.4.4 was editorially corrected in November 2007.1. Scope1.1 This test method covers the measurement of the totalmoisture in coal as it exists at the site, at t

3、he time, and underthe conditions it is sampled. It is applicable to coals as mined,processed, shipped, or used in normal commercial pursuits. Itis not applicable to coal-water slurries, sludges, or pulverizedproducts under 0.5-mm-diameter sieve size. It is applicable tocoals of all ranks within the

4、recognized limitations imposed byoxidation and decomposition characteristics of lower rankcoals. Because of its empirical nature, strict adherence to basicprinciples and permissive procedures are required for validresults (see Appendix X1). This complete standard is availableto producers, sellers, a

5、nd consumers as a total moisture methodwhen other procedures or modifications are not mutuallyagreed on.1.2 Since coal can vary from extremely wet (water-saturated) to completely dry, special emphasis must be placedon the sampling, sample preparation, and the moisture deter-mination itself to ensure

6、 total reliability of measurement.Therefore, this standard entails collection of the gross sample,sample preparation, and the method of determination.1.3 While it is recognized that such a standard may beunwieldy for routine usage in commercial operations, it canprovide a common base for agreement i

7、n cases of dispute orarbitration. The complete standard is referred to as the refereemethod. Embodied in the standard is the commercial methodstarting with the crushed and divided sample when the grosssample is not too wet to crush and divide. See Test MethodsD 2961 and D 3173 for other moisture met

8、hods.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establis

9、h appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 388 Classification of Coals by RankD 2013 Practice for Preparing Coal Samples for AnalysisD 2234/D 2234M P

10、ractice for Collection of a Gross Sampleof CoalD 2961 Test Method for Single-Stage Total Moisture Lessthan 15 % in Coal Reduced to 2.36-mm (No. 8 Sieve)TopsizeD 3173 Test Method for Moisture in theAnalysis Sample ofCoal and CokeD 5865 Test Method for Gross Calorific Value of Coal andCoke3. Terminolo

11、gy3.1 DefinitionsFor additional definitions of terms used inthis test method, refer to Terminology D 121.3.2 Definitions of Terms Specific to This Standard:3.2.1 air dryinga process of partial drying of a coalsample to bring it to near equilibrium with the atmosphere inthe room in which further redu

12、ction/division of the sample is totake place.3.2.2 air-dry lossthe loss in weight, expressed as apercent, resulting from each air-drying operation.3.2.3 easily oxidized coalslow-rank coals such as subbi-tuminous or lignitic coals.3.2.4 equilibriumcondition reached in air drying when thechange in wei

13、ght of the sample, under conditions of ambienttemperature and humidity, is no more than 0.1 %/h or 0.05 %/12 h.3.2.5 residual moisturethat moisture remaining in thesample after air drying.1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibili

14、ty of Subcommittee D05.21 on Methods ofAnalysis.Current edition approved Oct. 1, 2007. Published October 2007. Originallyapproved in 1974. Last previous edition approved in 2007 as D 330207e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at ser

15、viceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.6 total moisturesee Terminology D 121.4. Summary o

16、f Test Method (See Fig. 1)4.1 This test method is based on the loss in weight of a coalsample in an air atmosphere under rigidly controlled conditionsof temperature, time, and airflow.4.2 Alternative Methods:4.2.1 Referee Method, which may be used in cases ofdispute or arbitration. The gross moistur

17、e sample is air dried toequilibrate it with the atmosphere at each stage of division andreduction. No air drying is necessary if the sample is already atequilibrium with the atmosphere as indicated by stable weight.FIG. 1 Total Moisture Determination on Gross Sample, Special Moisture Subsample, or o

18、n Crushed and Divided SampleD 3302 07ae124.2.2 Commercial Method, which may be used in routinecommercial practice or when the concerned parties agree uponthis method. The crushed and divided moisture sample is airdried to equilibrate it with the atmosphere in which furtherdivision and reduction are

19、to occur.4.2.3 Residual moisture determination is made in a heatedforced-air circulation oven under rigidly defined conditions.4.3 Total moisture is calculated from loss (or gains) in airdrying and the residual moisture.5. Significance and Use5.1 The collection and treatment of the sample as specifi

20、edfor the referee method is intended for the express purpose ofdetermining the total moisture in coal. The standard is avail-able to producers, sellers, and consumers as a method ofdetermination when other techniques or modifications are notmutually agreed upon.5.2 The commercial method, which deter

21、mines total mois-ture content of the crushed and divided sample, is designated asthe method for total moisture for routine commercial practice.6. Apparatus6.1 Drying FloorA smooth clean floor area in a room freeof contamination by dust or other material and that permits aircirculation without excess

22、ive heat or air currents. Conditionsfor an air-drying floor should approach those established foroven drying as much as possible.6.2 Air-Drying OvenA device for passing slightly heatedair over the sample. The oven should be capable of maintaininga temperature of 10 to 15C (18 to 27F) above ambientte

23、mperature with a maximum oven temperature of 40C(104F) unless ambient temperature is above 40C (104F), inwhich case ambient temperature shall be used. In the case ofeasily oxidized coals, the temperature should not be more than10C (18F) above ambient temperature. Air changes shall beat the rate of o

24、ne to four per minute. A typical oven is shownin Fig. 2.6.3 Drying Pans:6.3.1 Pans for Gross Sample, noncorroding, weight-stableat temperature used, of sufficient size so that the sample can bespread to a depth of not more than twice the diameter of thelargest particles if larger than 13 mm (0.5 in.

25、) or not more than25-mm (1.0-in.) depth for smaller coal, with pan sides about 50to 75 mm (2 to 3 in.) high.6.3.2 Pans for Crushed and Divided Sample, noncorroding,weight-stable at temperature used, of sufficient size so that thesample can be spread to a depth of not more than 25 mm (1.0in.) with si

26、des not more than 38 mm (1.5 in.) high.6.4 Scale (Gross Sample)a scale of at least 45-kg (100-lbs) capacity and sensitive to 23 g (0.05 lbs) in 45 kg (100 lbs).6.5 Balance (Crushed Sample), sensitive to 0.1 g with acapacity sufficient to weigh pan, sample, and container.6.6 Laboratory Sample Contain

27、ersheavy vapor-impervious bags, properly sealed, or noncorroding cans such asthose with an airtight, friction top or screw top sealed with arubber gasket and pressure-sensitive tape for use in storage andtransport of the laboratory sample. Glass containers, sealedwith rubber gaskets, can be used, bu

28、t care must be taken toavoid breakage in transport.6.7 Drying Oven (for residual moisture on 250-m (No. 60)sieve by 0 sample)This oven is described in Test MethodD 3173 and can be of the form illustrated in Fig. 1 in TestMethod D 3173.6.8 Analytical Balance, sensitive to 0.1 mg (for residualmoisture

29、 on 250-m (No. 60) by 0 sample).6.9 Capsules, with covers, described in Test MethodD 3173.7. Precautions7.1 In collecting, handling, reducing, and dividing the grossmoisture sample, all operations shall be done rapidly and in asfew operations as possible, since moisture loss depends onseveral factor

30、s other than total moisture content, such as timerequired for crushing, atmospheric temperature and humidity,and type of crushing equipment.7.2 While awaiting preparation, the uncrushed gross mois-ture sample shall be sealed in appropriate containers in orderthat it be protected from moisture change

31、 as a result ofexposure to ambient air, rain, snow, wind, and sun, or contactwith absorbent materials.7.3 If the gross sample requires air drying, then the initialweight of the original gross moisture sample and containerFIG. 2 Air-Drying OvenD 3302 07ae13shall be recorded, and the moisture loss or

32、gain of sample andcontainers shall be determined before the sample is reduced.7.4 Whenever a distinct change of humidity occurs duringthe course of preparation of an air-dried sample, the subsampleshould be weighed and equilibrated with the new atmosphereand the weight loss or gain used in the calcu

33、lation of totalmoisture content.7.5 Whenever subsamples are stored or transported andmoisture condenses on the container, then the container andsubsample shall be weighed, equilibrated to the new atmo-sphere by air drying, and the weight loss or gain shall be usedin the calculation of total moisture

34、 content.7.6 Since most coals have a tendency to oxidize on exposureto air, the air-drying procedure should not be prolonged pastthe time necessary to bring the sample to equilibrium with thetemperature and humidity of the air in the room in whichfurther reduction and division are to be made. Easily

35、 oxidizedcoals must not be air dried at a temperature exceeding 10Cabove ambient temperature. In no case shall the air drying bedone at a temperature over 40C. Air drying of low-rank coalsshould not exceed 18 h because of oxidation. In the case oflignite, the goal of reaching equilibrium should be w

36、eighedagainst the possibility of oxidation.7.7 Protect crushed, divided, pulverized, or pulverizingsamples from atmospheric changes affecting surface moistureor otherwise affecting sample integrity.7.7.1 Procedures useful in maintaining uniform temperatureand humidity conditions and minimum airflow

37、in moisturedetermination and sample preparation area include the follow-ing: (1) closed dust control system, recycling filtered air; (2)hood over dust-producing equipment to minimize airflowrequired to remove dust; and (3) pulling makeup air fromwithin the building to replace exhausted air or using

38、temperedor conditioned makeup air.7.7.2 Avoid heatup of pulverizer by: (1) using pulverizerlarge enough to process sample quickly and (2) allowing timefor pulverizer to come to room temperature before reuse.8. Sampling8.1 The principles, terms, organization, and collection as setforth in Practice D

39、2234/D 2234M shall apply to the collectionof the total moisture sample. Particular attention is directed toSection 8. The increments as established in Table 2 of PracticeD 2234/D 2234M for mechanically cleaned coal are deemedadequate for general purpose sampling for total moisture.9. Procedure9.1 Ai

40、r-Drying Loss on Gross SampleReferee Method:9.1.1 Procedure A, Drying FloorThis procedure is par-ticularly applicable if the gross moisture sample is too large anamount to ship reasonably or is too wet to handle or shipwithout loss of moisture.9.1.1.1 Weigh and record the weight of the gross moistur

41、esample. Spread the sample on the drying floor to a depth of notmore than twice the top size of the coal. Mix or stir the coalfrom time to time, being careful not to lose any of the coalparticles. Continue the air drying and mixing until the surfaceof the sample appears dry. Weigh the entire sample

42、andredistribute over the floor for additional drying. Continue thedrying and stirring, weighing at 1- to 2-h intervals until theweight loss of the total sample becomes no more than 0.1 %/h(Note 1). Record the weight of the air dry sample.Avoid excessdrying.NOTE 1If the sample surface appears dry, an

43、d the time required forreduction and division is well established, air drying can be stopped whenthe weight loss is less than 0.1 % per twice the required time forprocessing. Example: If reduction and division of the sample is expectedto require 20 min, the air-drying procedure can be stopped when t

44、he rateof moisture loss is less than 0.1 %/40 min. If this procedure is used, asecond air drying is required to establish the 0.1 %/h rate before the finalpreparation of the laboratory sample.9.1.1.2 Proceed with sample reduction and division inaccordance with Practice D 2013, Section 9.2.3 or 9.2.4

45、,observing precautions of Practice D 2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.1.2 Procedure B, Air Drying Oven:9.1.2.1 Distribute the gross moisture sample over the re-quired number of tared pans. Weigh each pan with sample as itis filled from the gross samp

46、le. Place in an air-drying oven thathas been adjusted to maintain temperature no more than 10C(18F) above ambient temperature for easily oxidized coals orno more than 15C (27F) above ambient temperature for othercoals (oven temperature not to exceed 40C). Ambient air maybe used with no heating. Main

47、tain air circulation through theoven at a rate of one to four air exchanges per minute, but inno case should it be sufficiently high to blow fine particles fromthe pans. Gently stir the sample from time to time to ensureuniform drying throughout the sample. Continue drying withintermittent stirring

48、until the coal surfaces appear to be dry.Remove from oven, weigh, and record the weight. Return thepans with sample to the oven and continue the operation.Calculate the percent weight loss. Repeat the drying andweighing process at 1- to 2-h intervals until the weight loss isless than 0.1 %/h (Note 1

49、). Allow the sample to reach equilib-rium with ambient temperature and humidity before the finalair dry weight is recorded. Avoid excess drying.9.1.2.2 Proceed with sample reduction and division inaccordance with Practice D 2013, Section 9.2.3 or 9.2.4,observing precautions of Practice D 2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.2 Air-Drying Loss on Crushed and Divided Coal Sample,Referee and Commercial Method:9.2.1 Proceed with determination of air-drying losses (orgains) without unnecessary delay under eith