1、Designation: D 197 87 (Reapproved 2007)Standard Test Method forSampling and Fineness Test of Pulverized Coal1This standard is issued under the fixed designation D 197; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the fine-ness by sieve analysis of coal sampled from a dry pulverizingopera
3、tion. It is not applicable to products of wet milling or tofines that have clustered into an agglomerated mass.1.2 The values stated in inch-pound units shall be regardedas the standard. Sample weights of 1000 g or less shall beexpressed in metric units.1.3 This standard does not purport to address
4、all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E11 Specification
5、for Wire-Cloth Sieves for Testing Pur-poses3. Significance and Use3.1 This test method provides a means for assisting in theevaluation of pulverizers and pulverizer systems in terms offineness specifications. It may also be used to confirm theinfluence of coal fineness on combustion performance and
6、toevaluate carbon loss. By consent among interested parties, itmay be used for evaluation of coal fineness in preparation,pneumatic transfer systems, etc.4. Apparatus4.1 Sample ContainersHeavy vapor impervious bags,properly sealed, or noncorroding cans such as those with anairtight, friction top or
7、screw top sealed with a rubber gasketand pressure sensitive tape for use in storage and transport ofthe laboratory sample. Glass containers sealed with rubbergaskets may be used, but care must be taken to avoid breakagein transport.4.2 Drying OvenA device for passing slightly heated airover the samp
8、le. The oven should be capable of maintaining atemperature of 18 to 27F (10 to 15C) above room tempera-ture with a maximum oven temperature of 104F (40C). Airchanges should be at the rate of 1 to 4/min.4.3 Sieves, square-hole, woven-wire cloth conforming toSpecification E11:No. 8 USA Standard (2.36
9、mm)No. 16 USA Standard (1.18 mm)No. 30 USA Standard (600 m)No. 50 USA Standard (300 m)No. 100 USA Standard (150 m)No. 200 USA Standard (75 m)No. 325 USA Standard (45 m)The sieve frames shall be 8 in. (203 mm) in diameter, and theheight of the sieve from the top of the frame to the cloth shallbe eith
10、er 2 in. (50.8 mm) or 1 in. (25.4 mm). Selection ofspecific sizes is optional, depending on the objective of the test.4.3.1 Since the finer mesh sieves in particular are suscep-tible to damage by distortion resulting from undue pressure,accidental scraping with hard brushes, etc., each sieve shouldb
11、e closely inspected and discarded if it shows evidence ofdamage.4.4 Mechanical Sieving MachineThe mechanical sievingmachine shall be designed to provide both a circular motionand a tapping action. It shall be designed to accept an assemblyof vertically nested circular sieves as described in 4.3. The
12、machine action shall be such that results as described inSection 7 are obtained within the allotted time frame. Actionshall not be sufficiently severe to generate new fines by particledegradation. To facilitate the sieving operation, a controlswitch device with timer is recommended. Other equipmentd
13、esigns may be used provided the results are comparable.4.5 Balance, LaboratoryApproximately 1000-g capacity,sensitivity 0.1 g.4.6 Sampling Device (Storage System)An instrument(scoop, dipper, or other suitable device) for collecting incre-ments that will constitute the total sample.4.7 Sampling Devic
14、e (Direct-Fired System)Apparatus asdescribed in 6.2.1 and 6.2.2.1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.07 on PhysicalCharacteristics of Coal.Current edition approved Oct. 1, 2007. Published October 2007.
15、Originallypublished in 1924. Last previous edition approved in 2002 as D 197 87 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summar
16、y page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.8 Sample Riffle with PansA manual sample divider thatsplits the coal stream into a number of alternate elements.Riffle divisions should be in the size range
17、from14 to12 in. (6.4to 12.7 mm).5. Sampling, Storage System5.1 In the pulverized coal storage system, the coal afterpulverization is conveyed into bins.5.1.1 Collection of Gross SampleCollect not less than tenincrements of representative pulverized coal preferably as it isbeing discharged from the c
18、ollector. This is best accomplishedby collecting increments of not less than 50 g at regularintervals by means of a scoop, dipper, or a device capable ofremoving an increment from a specific location within thestream of pulverized coal. Place the increments in the samplecontainer and seal.5.1.2 Prep
19、aration of the Laboratory SampleA small riffle(Fig. 1) can be used for mixing and dividing the sample bysplitting. An enclosed riffle is preferred. Mix the gross sampleby splitting and recombining the halves a minimum of twotimes. Divide the sample amount by successive riffle splittingoperations on
20、one half of the sample until the sample is dividedto approximately 500 g for the laboratory sample. To correctlyuse the riffle, the sample must be poured over the side of a pan(a third pan is necessary) and not from an end or corner, norfrom a container such as, a pail or jar. Transfer the sample to
21、a sample container and seal.5.1.3 As an alternative to riffle mixing and splitting, thesample can be prepared as follows: Place the gross sample ona sheet of rubber, plastic, or paper and mix it by raising first onecorner of the cloth and then the other so as to roll the coal overand over at least 2
22、0 times. After mixing, divide the sample.Continue the operations of mixing and dividing until thesample is divided sufficiently so that all of one of the divisionsweighs approximately 500 g. This shall constitute the labora-tory sample.6. Sampling, Direct-Fired System6.1 In the direct-fired system,
23、the coal is pulverized anddelivered directly to the furnace in an air stream. It is difficultto obtain representative samples, as it is necessary to samplethe coal from a moving stream of coal-air mixture inside thepipe between the pulverizer and furnace. It is preferable tocollect such samples from
24、 vertical pipes, as in horizontal pipesa greater amount of segregation may take place.6.2 Apparatus for Sample CollectionBecause it is difficultto collect a representative sample of solids from a movingcoal-air stream, it is essential that the equipment and samplingprocedures are uniformly consisten
25、t to assure valid and repro-ducible results. Recommended equipment and sampling ar-rangements are shown in Fig. 2 and Fig. 3. Except incircumstances where stationary interferences in the area aroundthe sampling location prohibits the use of the samplingequipment as shown in Fig. 3, changes to the eq
26、uipment shouldnot be allowed. Changes may produce inconsistent results.6.2.1 Fig. 2 shows the recommended arrangement for sam-pling pulverized coal in a direct-fired system using a dustlesssampling connection with an aspirator and a cyclone collector.In collecting the sample, turn on the compressed
27、air to thedustless connection and adjust to give a balanced pressure atthe connection. Insert the sampling tip into the dustlessconnection with the tip facing directly into the coal-air stream.Readjust the compressed air to give a balanced pressure withthe nozzle inserted. Traverse the fuel transpor
28、t line across theentire diameter of the pipe by moving at a uniform rate with thetip facing directly into the coal-air stream. The aspirating air onthe cyclone collector may or may not be used, depending onthe static pressure in the fuel transport line, as discussed in6.3.7.6.2.2 Fig. 3 shows detail
29、ed dimensions of a recommendedsampling tip. The area of the tip shown is 0.5 by 0.95 in. or0.475 in.2(12.7 by 24.1 mm or 306 mm2), which is theprojected area of the tip facing the coal-air stream. Other tipconfigurations and dimensions can be employed provided theypermit the collection of an unbiase
30、d sample from the coalstream. See Appendix X1.6.3 Collection of Gross Sample:6.3.1 In sampling, it is essential that the velocity into thesampling tip be nearly the same as the velocity in the pipe. Ifthe velocity in the sampling tube is insufficient, the full quotaof the coarse particles will be en
31、trained, but some of the fineparticles that should be caught will follow the air in passingaround the tip. If the velocity in the sampling tube is greater,more than the proper number of fine particles will be drawninto the sampling tip.6.3.2 A procedure for confirming sample validity is in-cluded in
32、 Appendix X4.6.3.3 A sample obtained in a given time should be weighedand compared with the weight of coal passing through the fueltransport line. The weight of the coal passing through the pipemay be determined from the total coal to the pulverizer dividedby number of pipes. The weight of coal pass
33、ing through thefuel transport line, multiplied by the ratio of the cross-sectionalarea of the sampling tip to that of the pipe, should beapproximately equal to the sample weight (see 6.3.9). Forexample, if a pulverizer has an output of 63 000 lb of coal perhour passing through six lines, and if each
34、 line is 15.25 in. (387mm) in inside diameter, with a cross-sectional area of 182.65FIG. 1 Sample Divider (Riffle)D 197 87 (2007)2in.2(1170 cm2) and if the standard sampler has a tip opening of0.5 by 0.95 in. (12.7 mm by 24.1 mm) and a cross-sectionalarea of 0.475 in.2(306 mm2), the sample rate per
35、minute with100 % recovery should then be as follows:Sample rate, lb/min = 63 000 lb/h-pulverizer 3 1h/60min3 1pulverizer/6 lines 3 0.475 in.2/sampler/182.65 in.2/line 3 1 sam-pler/1 line = 0.455 lb/min-line (206 g/min-line)Sampling for a 3-min period should then be 1.37 lb (618 g)for 100 % recovery.
36、6.3.4 If the recovery is between 90 and 110 %, the sampleshall be considered satisfactory as to collection rate for the pipeand flow velocities. See Appendix X2.6.3.5 After taking one or two samples and weighing themfor confirmation, the collector vent control can be adjusted togive a recovery withi
37、n the 90 and 110 % limits. Discard thosesamples that do not meet the recovery limits.6.3.6 If the static pressure in the fuel transport line is so highthat the recovery is above 110 % with all aspirator air shut off,throttle the flow from the cyclone to reduce the recovery to thedesired range betwee
38、n 90 and 110 %. This can be done byinstalling a valve or orifice at the cyclone collector ventdischarge (see Fig. 2).6.3.7 Samples shall be taken by carefully traversing at leasttwo complete diameters 90 apart. Two common samplingmethods are the continuous transversing technique or the equalarea met
39、hod. If preliminary samples taken at each individualline show wide variations in fineness and recovery, betterlocations should be used. The location shall preferably be in aFIG. 2 Recommended Arrangement for Sampling Pulverized Coal in a Direct-Fired SystemD 197 87 (2007)3vertical pipe as far as pos
40、sible from preceding bends, changesof cross section, or valves. A distance of seven to ten times thepipe diameter is desirable. Sampling connections shall becleared of accumulated coal before taking samples.6.3.8 Precautions should be taken to keep the samples abovethe water dew point during collect
41、ion.6.3.9 When the sampling points are in the pipes and apulverizer has two or more pipes, the total weight of thesamples from all the pipes should be compared with total coalweight to check the recovery, as explained in 6.3.2-6.3.4.6.3.10 When the air velocity and static pressure in each fueltransp
42、ort line are nearly equal, the same cyclone throttle settingand the same air pressure at the aspirator should give about thesame sample tip velocity. Then, even if the coal is not equallydistributed in the several pipes, duplicate cyclone throttlesettings should result in samples from each pipe that
43、 will beapproximately proportional in weight to the coal distribution,but the total should be between 90 and 110 % of the propor-tional total coal flow. Samples at each point should be taken forequal time periods and not by equal amounts collected. Eachsample may be sieved separately and the weighte
44、d averageused to obtain the average fineness of the pulverizer output orthe samples may be thoroughly mixed and one sieve determi-nation made of the mixture, since the sample from each linerepresents the proper proportion of the pulverizer output.6.3.11 In storage systems, take samples at the outlet
45、 of thecyclone collector. If the sampling location is under suction,provide the container with a cover that can be closed before itis withdrawn from the sampling connection.6.3.12 The fineness of pulverized coal samples taken in astorage system shall be either the weighted average of thefineness of
46、all samples taken during the test or the fineness ofthe composite sample.NOTE 1The collection of a valid representative sample requires bothproperly maintained equipment and close attention to details by thesamplers. The collection is best accomplished by one person actuallysampling, assisted by a p
47、erson to facilitate equipment and samplehandling.7. Fineness Test7.1 Drying SampleAir-dry the entire laboratory sample ina drying oven at 18 to 27F (10 to 15C) above roomtemperature. Continue the drying until the loss in weight is notmore than 0.1 %/h.7.2 Dividing the SampleAfter air-drying, divide
48、thesample amount to 50 to 100 g as described in 5.1.2 and 5.1.3.7.3 Sieve Test:7.3.1 Select the proper sieve sizes for the test and thor-oughly clean each by carefully brushing and tapping to assurethat no solid particles from previous tests are trapped in themeshes. Nest the sieves together with th
49、e coarsest mesh at thetop and in descending order with the finest mesh at the bottom.Set a pan receiver at the bottom of the nest to receive theundersize. Place 45 to 55 g of coal weighed to 60.05 g on thetop sieve and cover with a fitted cover to prevent loss.7.3.2 Place the assembled set into the sieving machine andmake the necessary adjustments for the sieving operation.Adjust the timer for a 10-min period and start the machine. Forhand sieving alternative, see Appendix X3.7.3.3 At the end of the sieving period, remove the stack, slipoff the receiver p
