ASTM D197-87(2007)
(Test Method)Standard Test Method for Sampling and Fineness Test of Pulverized Coal
Standard Test Method for Sampling and Fineness Test of Pulverized Coal
SIGNIFICANCE AND USE
This test method provides a means for assisting in the evaluation of pulverizers and pulverizer systems in terms of fineness specifications. It may also be used to confirm the influence of coal fineness on combustion performance and to evaluate carbon loss. By consent among interested parties, it may be used for evaluation of coal fineness in preparation, pneumatic transfer systems, etc.
SCOPE
1.1 This test method covers the determination of the fineness by sieve analysis of coal sampled from a dry pulverizing operation. It is not applicable to products of wet milling or to fines that have clustered into an agglomerated mass.
1.2 The values stated in inch-pound units shall be regarded as the standard. Sample weights of 1000 g or less shall be expressed in metric units.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: D197 − 87 (Reapproved2007)
Standard Test Method for
Sampling and Fineness Test of Pulverized Coal
This standard is issued under the fixed designation D197; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope the laboratory sample. Glass containers sealed with rubber
gaskets may be used, but care must be taken to avoid breakage
1.1 This test method covers the determination of the fine-
in transport.
ness by sieve analysis of coal sampled from a dry pulverizing
operation. It is not applicable to products of wet milling or to
4.2 Drying Oven—A device for passing slightly heated air
fines that have clustered into an agglomerated mass.
over the sample. The oven should be capable of maintaining a
temperature of 18 to 27°F (10 to 15°C) above room tempera-
1.2 The values stated in inch-pound units shall be regarded
ture with a maximum oven temperature of 104°F (40°C). Air
as the standard. Sample weights of 1000 g or less shall be
changes should be at the rate of 1 to 4/min.
expressed in metric units.
4.3 Sieves, square-hole, woven-wire cloth conforming to
1.3 This standard does not purport to address all of the
Specification E11:
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- No. 8 USA Standard (2.36 mm)
No. 16 USA Standard (1.18 mm)
priate safety and health practices and determine the applica-
No. 30 USA Standard (600 µm)
bility of regulatory limitations prior to use.
No. 50 USA Standard (300 µm)
No. 100 USA Standard (150 µm)
No. 200 USA Standard (75 µm)
2. Referenced Documents
No. 325 USA Standard (45 µm)
2.1 ASTM Standards:
Thesieveframesshallbe8in.(203mm)indiameter,andthe
E11Specification forWovenWireTest Sieve Cloth andTest
height of the sieve from the top of the frame to the cloth shall
Sieves
be either 2 in. (50.8 mm) or 1 in. (25.4 mm). Selection of
specificsizesisoptional,dependingontheobjectiveofthetest.
3. Significance and Use
4.3.1 Since the finer mesh sieves in particular are suscep-
3.1 This test method provides a means for assisting in the
tible to damage by distortion resulting from undue pressure,
evaluation of pulverizers and pulverizer systems in terms of
accidental scraping with hard brushes, etc., each sieve should
fineness specifications. It may also be used to confirm the
be closely inspected and discarded if it shows evidence of
influence of coal fineness on combustion performance and to
damage.
evaluate carbon loss. By consent among interested parties, it
4.4 Mechanical Sieving Machine—The mechanical sieving
may be used for evaluation of coal fineness in preparation,
machine shall be designed to provide both a circular motion
pneumatic transfer systems, etc.
andatappingaction.Itshallbedesignedtoacceptanassembly
of vertically nested circular sieves as described in 4.3. The
4. Apparatus
machine action shall be such that results as described in
4.1 Sample Containers—Heavy vapor impervious bags,
Section 7 are obtained within the allotted time frame. Action
properly sealed, or noncorroding cans such as those with an
shallnotbesufficientlyseveretogeneratenewfinesbyparticle
airtight, friction top or screw top sealed with a rubber gasket
degradation. To facilitate the sieving operation, a control
and pressure sensitive tape for use in storage and transport of
switch device with timer is recommended. Other equipment
designs may be used provided the results are comparable.
This test method is under the jurisdiction of ASTM Committee D05 on Coal
4.5 Balance, Laboratory—Approximately 1000-g capacity,
and Coke and is the direct responsibility of Subcommittee D05.07 on Physical
sensitivity 0.1 g.
Characteristics of Coal.
Current edition approved Oct. 1, 2007. Published October 2007. Originally
4.6 Sampling Device (Storage System)—An instrument
published in 1924. Last previous edition approved in 2002 as D197–87 (2002).
(scoop, dipper, or other suitable device) for collecting incre-
DOI: 10.1520/D0197-87R07.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ments that will constitute the total sample.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.7 Sampling Device (Direct-Fired System)—Apparatus as
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. described in 6.2.1 and 6.2.2.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D197 − 87 (2007)
4.8 Sample Riffle with Pans—Amanual sample divider that to obtain representative samples, as it is necessary to sample
splits the coal stream into a number of alternate elements. the coal from a moving stream of coal-air mixture inside the
1 1
Riffledivisionsshouldbeinthesizerangefrom ⁄4to ⁄2in.(6.4 pipe between the pulverizer and furnace. It is preferable to
to 12.7 mm). collect such samples from vertical pipes, as in horizontal pipes
a greater amount of segregation may take place.
5. Sampling, Storage System
6.2 Apparatus for Sample Collection—Becauseitisdifficult
5.1 In the pulverized coal storage system, the coal after
to collect a representative sample of solids from a moving
pulverization is conveyed into bins.
coal-air stream, it is essential that the equipment and sampling
5.1.1 Collection of Gross Sample—Collect not less than ten
procedures are uniformly consistent to assure valid and repro-
increments of representative pulverized coal preferably as it is
ducible results. Recommended equipment and sampling ar-
being discharged from the collector. This is best accomplished
rangements are shown in Fig. 2 and Fig. 3. Except in
by collecting increments of not less than 50 g at regular
circumstanceswherestationaryinterferencesintheareaaround
intervals by means of a scoop, dipper, or a device capable of
the sampling location prohibits the use of the sampling
removing an increment from a specific location within the
equipmentasshowninFig.3,changestotheequipmentshould
stream of pulverized coal. Place the increments in the sample
not be allowed. Changes may produce inconsistent results.
container and seal.
6.2.1 Fig. 2 shows the recommended arrangement for sam-
5.1.2 Preparation of the Laboratory Sample—Asmall riffle
pling pulverized coal in a direct-fired system using a dustless
(Fig. 1) can be used for mixing and dividing the sample by
sampling connection with an aspirator and a cyclone collector.
splitting.An enclosed riffle is preferred. Mix the gross sample
In collecting the sample, turn on the compressed air to the
by splitting and recombining the halves a minimum of two
dustless connection and adjust to give a balanced pressure at
times. Divide the sample amount by successive riffle splitting
the connection. Insert the sampling tip into the dustless
operationsononehalfofthesampleuntilthesampleisdivided
connection with the tip facing directly into the coal-air stream.
to approximately 500 g for the laboratory sample. To correctly
Readjust the compressed air to give a balanced pressure with
use the riffle, the sample must be poured over the side of a pan
the nozzle inserted. Traverse the fuel transport line across the
(a third pan is necessary) and not from an end or corner, nor
entirediameterofthepipebymovingatauniformratewiththe
from a container such as, a pail or jar. Transfer the sample to
tipfacingdirectlyintothecoal-airstream.Theaspiratingairon
a sample container and seal.
the cyclone collector may or may not be used, depending on
5.1.3 As an alternative to riffle mixing and splitting, the
the static pressure in the fuel transport line, as discussed in
sample can be prepared as follows: Place the gross sample on
6.3.7.
asheetofrubber,plastic,orpaperandmixitbyraisingfirstone
6.2.2 Fig. 3 shows detailed dimensions of a recommended
corneroftheclothandthentheothersoastorollthecoalover
sampling tip. The area of the tip shown is 0.5 by 0.95 in. or
and over at least 20 times. After mixing, divide the sample.
2 2
0.475 in. (12.7 by 24.1 mm or 306 mm ), which is the
Continue the operations of mixing and dividing until the
projected area of the tip facing the coal-air stream. Other tip
sample is divided sufficiently so that all of one of the divisions
configurations and dimensions can be employed provided they
weighs approximately 500 g. This shall constitute the labora-
permit the collection of an unbiased sample from the coal
tory sample.
stream. See Appendix X1.
6. Sampling, Direct-Fired System
6.3 Collection of Gross Sample:
6.1 In the direct-fired system, the coal is pulverized and
6.3.1 In sampling, it is essential that the velocity into the
delivered directly to the furnace in an air stream. It is difficult sampling tip be nearly the same as the velocity in the pipe. If
the velocity in the sampling tube is insufficient, the full quota
of the coarse particles will be entrained, but some of the fine
particles that should be caught will follow the air in passing
around the tip. If the velocity in the sampling tube is greater,
more than the proper number of fine particles will be drawn
into the sampling tip.
6.3.2 A procedure for confirming sample validity is in-
cluded in Appendix X4.
6.3.3 Asample obtained in a given time should be weighed
and compared with the weight of coal passing through the fuel
transport line. The weight of the coal passing through the pipe
maybedeterminedfromthetotalcoaltothepulverizerdivided
by number of pipes. The weight of coal passing through the
fueltransportline,multipliedbytheratioofthecross-sectional
area of the sampling tip to that of the pipe, should be
approximately equal to the sample weight (see 6.3.9). For
example, if a pulverizer has an output of 63000 lb of coal per
hourpassingthroughsixlines,andifeachlineis15.25in.(387
FIG. 1 Sample Divider (Riffle) mm) in inside diameter, with a cross-sectional area of 182.65
D197 − 87 (2007)
FIG. 2 Recommended Arrangement for Sampling Pulverized Coal in a Direct-Fired System
2 2
in. (1170cm )andifthestandardsamplerhasatipopeningof give a recovery within the 90 and 110% limits. Discard those
0.5 by 0.95 in. (12.7 mm by 24.1 mm) and a cross-sectional samples that do not meet the recovery limits.
2 2
area of 0.475 in. (306 mm ), the sample rate per minute with
6.3.6 Ifthestaticpressureinthefueltransportlineissohigh
100% recovery should then be as follows:
that the recovery is above 110% with all aspirator air shut off,
Sample rate, lb/min = 63 000 lb/h-pulverizer × 1 h/60 min × 1
throttle the flow from the cyclone to reduce the recovery to the
2 2
pulverizer/6 lines × 0.475 in. /sampler/182.65 in. /line × 1 sam-
desired range between 90 and 110%. This can be done by
pler/1 line = 0.455 lb/min-line (206 g/min-line)
installing a valve or orifice at the cyclone collector vent
Sampling for a 3-min period should then be 1.37 lb (618 g)
discharge (see Fig. 2).
for 100% recovery.
6.3.7 Samples shall be taken by carefully traversing at least
6.3.4 If the recovery is between 90 and 110%, the sample
two complete diameters 90° apart. Two common sampling
shallbeconsideredsatisfactoryastocollectionrateforthepipe
methodsarethecontinuoustransversingtechniqueortheequal
and flow velocities. See Appendix X2.
6.3.5 After taking one or two samples and weighing them area method. If preliminary samples taken at each individual
for confirmation, the collector vent control can be adjusted to line show wide variations in fineness and recovery, better
D197 − 87 (2007)
FIG. 3 Detail of Sampling Nozzle
locations should be used. The location shall preferably be in a fineness of all samples taken during the test or the fineness of
vertical pipe as far as possible from preceding bends, changes the composite sample.
of cross section, or valves.Adistance of seven to ten times the
NOTE 1—The collection of a valid representative sample requires both
pipe diameter is desirable. Sampling connections shall be
properly maintained equipment and close attention to details by the
cleared of accumulated coal before taking samples.
samplers. The collection is best accomplished by one person actually
sampling, assisted by a person to facilitate equipment and sample
6.3.8 Precautionsshouldbetakentokeepthesamplesabove
handling.
the water dew point during collection.
6.3.9 When the sampling points are in the pipes and a
7. Fineness Test
pulverizer has two or more pipes, the total weight of the
samples from all the pipes should be compared with total coal
7.1 Drying Sample—Air-dry the entire laboratory sample in
weight to check the recovery, as explained in 6.3.2-6.3.4.
a drying oven at 18 to 27°F (10 to 15°C) above room
6.3.10 Whentheairvelocityandstaticpressureineachfuel
temperature. Continue the drying until the loss in weight is not
transportlinearenearlyequal,thesamecyclonethrottlesetting
more than 0.1%/h.
andthesameairpressureattheaspiratorshouldgiveaboutthe
7.2 Dividing the Sample—After air-drying, divide the
same sample tip velocity. Then, even if the coal is not equally
sample amount to 50 to 100 g as described in 5.1.2 and 5.1.3.
distributed in the several pipes, duplicate cyclone throttle
7.3 Sieve Test:
settings should result in samples from each pipe that will be
7.3.1 Select the proper sieve sizes for the test and thor-
approximately proportional in weight to the coal distribution,
oughly clean each by carefully brushing and tapping to assure
but the total should be between 90 and 110% of the propor-
that no solid particles from previous tests are trapped in the
tionaltotalcoalflow.Samplesateachpointshouldbetakenfor
meshes. Nest the sieves together with the coarsest mesh at the
equal time periods and not by equal amounts collected. Each
topandindescendingorderwiththefinestmeshatthebottom.
sample may be sieved separately and the weighted average
Set a pan receiver at the bottom of the nest to receive the
used to obtain the average fineness of the pulverizer output or
undersize. Place 45 to 55 g of coal weighed to 60.05 g on the
the samples may be thoroughly mixed and one sieve determi-
top sieve and cover with a fitted cover to prevent loss.
nation made of the mixture, since the sample from each line
represents the proper proportion of the pulverizer output. 7.3.2 Place the assembled set into the sieving machine and
make the necessary adjustments for the sieving operation.
6.3.11 In storage systems, take samples at the outlet of the
cyclone collector. If the sampling location is under suction, Adjustthetimerfora10
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