ASTM D197-87(2002)
(Test Method)Standard Test Method for Sampling and Fineness Test of Pulverized Coal
Standard Test Method for Sampling and Fineness Test of Pulverized Coal
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.
1.3 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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Designation:D197–87(Reapproved 2002)
Standard Test Method for
Sampling and Fineness Test of Pulverized Coal
This standard is issued under the fixed designation D 197; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 Drying Oven—A device for passing slightly heated air
over the sample. The oven should be capable of maintaining a
1.1 This test method covers the determination of the fine-
temperature of 18 to 27°F (10 to 15°C) above room tempera-
ness by sieve analysis of coal sampled from a dry pulverizing
ture with a maximum oven temperature of 104°F (40°C). Air
operation. It is not applicable to products of wet milling or to
changes should be at the rate of 1 to 4/min.
fines that have clustered into an agglomerated mass.
4.3 Sieves, square-hole, woven-wire cloth conforming to
1.2 The values stated in inch-pound units shall be regarded
SpecificationE11:
as the standard. Sample weights of 1000 g or less shall be
No. 8 USA Standard (2.36 mm)
expressed in metric units.
No. 16 USA Standard (1.18 mm)
1.3 This standard does not purport to address all of the
No. 30 USA Standard (600 µm)
safety concerns, if any, associated with its use. It is the
No. 50 USA Standard (300 µm)
No. 100 USA Standard (150 µm)
responsibility of the user of this standard to establish appro-
No. 200 USA Standard (75 µm)
priate safety and health practices and determine the applica-
No. 325 USA Standard (45 µm)
bility of regulatory limitations prior to use.
Thesieveframesshallbe8in.(203mm)indiameter,andthe
2. Referenced Documents height of the sieve from the top of the frame to the cloth shall
be either 2 in. (50.8 mm) or 1 in. (25.4 mm). Selection of
2.1 ASTM Standards:
specificsizesisoptional,dependingontheobjectiveofthetest.
E11 Specification for Wire-Cloth Sieves for Testing Pur-
2 4.3.1 Since the finer mesh sieves in particular are suscep-
poses
tible to damage by distortion resulting from undue pressure,
3. Significance and Use accidental scraping with hard brushes, etc., each sieve should
be closely inspected and discarded if it shows evidence of
3.1 This test method provides a means for assisting in the
damage.
evaluation of pulverizers and pulverizer systems in terms of
4.4 Mechanical Sieving Machine—The mechanical sieving
fineness specifications. It may also be used to confirm the
machine shall be designed to provide both a circular motion
influence of coal fineness on combustion performance and to
and a tapping action. It shall be designed to accept an assembly
evaluate carbon loss. By consent among interested parties, it
of vertically nested circular sieves as described in 4.3. The
may be used for evaluation of coal fineness in preparation,
machine action shall be such that results as described in
pneumatic transfer systems, etc.
Section 7 are obtained within the allotted time frame. Action
4. Apparatus
shall not be sufficiently severe to generate new fines by particle
degradation. To facilitate the sieving operation, a control
4.1 Sample Containers—Heavy vapor impervious bags,
switch device with timer is recommended. Other equipment
properly sealed, or noncorroding cans such as those with an
designs may be used provided the results are comparable.
airtight, friction top or screw top sealed with a rubber gasket
4.5 Balance, Laboratory—Approximately 1000-g capacity,
and pressure sensitive tape for use in storage and transport of
sensitivity 0.1 g.
the laboratory sample. Glass containers sealed with rubber
4.6 Sampling Device (Storage System)—An instrument
gaskets may be used, but care must be taken to avoid breakage
(scoop, dipper, or other suitable device) for collecting incre-
in transport.
ments that will constitute the total sample.
4.7 Sampling Device (Direct-Fired System)—Apparatus as
described in 6.2.1 and 6.2.2.
This test method is under the jurisdiction of ASTM Committee D05 on Coal
and Coke, and is the direct responsibility of Subcommittee D05.07 on Physical
4.8 Sample Riffle with Pans—Amanual sample divider that
Characteristics of Coal.
splits the coal stream into a number of alternate elements.
Current edition approved Sept. 25, 1987. Published November 1987. Originally
1 1
e1
Riffledivisionsshouldbeinthesizerangefrom ⁄4to ⁄2in.(6.4
published as D 197 – 24 T. Last previous edition D 197 – 87 (1994) .
Annual Book of ASTM Standards, Vol 14.02. to 12.7 mm).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D197–87 (2002)
5. Sampling, Storage System collect such samples from vertical pipes, as in horizontal pipes
a greater amount of segregation may take place.
5.1 In the pulverized coal storage system, the coal after
pulverization is conveyed into bins. 6.2 ApparatusforSampleCollection—Because it is difficult
to collect a representative sample of solids from a moving
5.1.1 Collection of Gross Sample—Collect not less than ten
increments of representative pulverized coal preferably as it is coal-air stream, it is essential that the equipment and sampling
being discharged from the collector. This is best accomplished procedures are uniformly consistent to assure valid and repro-
by collecting increments of not less than 50 g at regular ducible results. Recommended equipment and sampling ar-
intervals by means of a scoop, dipper, or a device capable of rangements are shown in Fig. 2 and Fig. 3. Except in
removing an increment from a specific location within the
circumstanceswherestationaryinterferencesintheareaaround
stream of pulverized coal. Place the increments in the sample the sampling location prohibits the use of the sampling
container and seal.
equipmentasshowninFig.3,changestotheequipmentshould
5.1.2 Preparation of the Laboratory Sample—Asmall riffle
not be allowed. Changes may produce inconsistent results.
(Fig. 1) can be used for mixing and dividing the sample by
6.2.1 Fig. 2 shows the recommended arrangement for sam-
splitting. An enclosed riffle is preferred. Mix the gross sample
pling pulverized coal in a direct-fired system using a dustless
by splitting and recombining the halves a minimum of two
sampling connection with an aspirator and a cyclone collector.
times. Divide the sample amount by successive riffle splitting
In collecting the sample, turn on the compressed air to the
operations on one half of the sample until the sample is divided
dustless connection and adjust to give a balanced pressure at
to approximately 500 g for the laboratory sample. To correctly
the connection. Insert the sampling tip into the dustless
use the riffle, the sample must be poured over the side of a pan
connection with the tip facing directly into the coal-air stream.
(a third pan is necessary) and not from an end or corner, nor
Readjust the compressed air to give a balanced pressure with
from a container such as, a pail or jar. Transfer the sample to
the nozzle inserted. Traverse the fuel transport line across the
a sample container and seal.
entirediameterofthepipebymovingatauniformratewiththe
5.1.3 As an alternative to riffle mixing and splitting, the
tipfacingdirectlyintothecoal-airstream.Theaspiratingairon
sample can be prepared as follows: Place the gross sample on
the cyclone collector may or may not be used, depending on
asheetofrubber,plastic,orpaperandmixitbyraisingfirstone
the static pressure in the fuel transport line, as discussed in
corner of the cloth and then the other so as to roll the coal over
6.3.7.
and over at least 20 times. After mixing, divide the sample.
6.2.2 Fig. 3 shows detailed dimensions of a recommended
Continue the operations of mixing and dividing until the
sampling tip. The area of the tip shown is 0.5 by 0.95 in. or
sample is divided sufficiently so that all of one of the divisions
2 2
0.475 in. (12.7 by 24.1 mm or 306 mm ), which is the
weighs approximately 500 g. This shall constitute the labora-
projected area of the tip facing the coal-air stream. Other tip
tory sample.
configurations and dimensions can be employed provided they
permit the collection of an unbiased sample from the coal
6. Sampling, Direct-Fired System
stream. See Appendix X1.
6.1 In the direct-fired system, the coal is pulverized and
6.3 Collection of Gross Sample:
delivered directly to the furnace in an air stream. It is difficult
6.3.1 In sampling, it is essential that the velocity into the
to obtain representative samples, as it is necessary to sample
sampling tip be nearly the same as the velocity in the pipe. If
the coal from a moving stream of coal-air mixture inside the
the velocity in the sampling tube is insufficient, the full quota
pipe between the pulverizer and furnace. It is preferable to
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
may be determined from the total coal to the pulverizer divided
by number of pipes. The weight of coal passing through the
fuel transport line, multiplied by the ratio of the cross-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 63 000 lb of coal per
hourpassingthroughsixlines,andifeachlineis15.25in.(387
mm) in inside diameter, with a cross-sectional area of 182.65
2 2
in. (1170 cm ) and if the standard sampler has a tip opening of
FIG. 1 Sample Divider (Riffle) 0.5 by 0.95 in. (12.7 mm by 24.1 mm) and a cross-sectional
D197–87 (2002)
FIG. 2 Recommended Arrangement for Sampling Pulverized Coal in a Direct-Fired System
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,
throttle the flow from the cyclone to reduce the recovery to the
Sample rate, lb/min = 63 000 lb/h-pulverizer 31h/60min 3 1
2 2
pulverizer/6 lines 3 0.475 in. /sampler/182.65 in. /line 3 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
methods are the continuous transversing technique or the equal
and flow velocities. See Appendix X2.
area method. If preliminary samples taken at each individual
6.3.5 After taking one or two samples and weighing them line show wide variations in fineness and recovery, better
for confirmation, the collector vent control can be adjusted to locations should be used. The location shall preferably be in a
give a recovery within the 90 and 110 % limits. Discard those vertical pipe as far as possible from preceding bends, changes
samples that do not meet the recovery limits. of cross section, or valves.Adistance of seven to ten times the
D197–87 (2002)
FIG. 3 Detail of Sampling Nozzle
samplers. The collection is best accomplished by one person actually
pipe diameter is desirable. Sampling connections shall be
sampling, assisted by a person to facilitate equipment and sample
cleared of accumulated coal before taking samples.
handling.
6.3.8 Precautionsshouldbetakentokeepthesamplesabove
the water dew point during collection.
7. Fineness Test
6.3.9 When the sampling points are in the pipes and a
7.1 Drying Sample—Air-dry the entire laboratory sample in
pulverizer has two or more pipes, the total weight of the
a drying oven at 18 to 27°F (10 to 15°C) above room
samples from all the pipes should be compared with total coal
temperature. Continue the drying until the loss in weight is not
weight to check the recovery, as explained in 6.3.2-6.3.4.
more than 0.1 %/h.
6.3.10 When the air velocity and static pressure in each fuel
7.2 Dividing the Sample—After air-drying, divide the
transportlinearenearlyequal,thesamecyclonethrottlesetting
sample amount to 50 to 100 g as described in 5.1.2 and 5.1.3.
and the same air pressure at the aspirator should give about the
7.3 Sieve Test:
same sample tip velocity. Then, even if the coal is not equally
distributed in the several pipes, duplicate cyclone throttle
7.3.1 Select the proper sieve sizes for the test and thor-
settings should result in samples from each pipe that will be oughly clean each by carefully brushing and tapping to assure
approximately proportional in weight to the coal distribution,
that no solid particles from previous tests are trapped in the
but the total should be between 90 and 110 % of the propor- meshes. Nest the sieves together with the coarsest mesh at the
tional total coal flow. Samples at each point should be taken for
top and in descending order with the finest mesh at the bottom.
equal time periods and not by equal amounts collected. Each
Set a pan receiver at the bottom of the nest to receive the
sample may be sieved separately and the weighted average
undersize. Place 45 to 55 g of coal weighed to 60.05 g on the
used to obtain the average fineness of the pulverizer output or
top sieve and cover with a fitted cover to prevent loss.
the samples may be thoroughly mixed and one sieve determi-
7.3.2 Place the assembled set into the sieving machine and
nation made of the mixture, since the sample from each line
make the necessary adjustments for the sieving operation.
represents the proper proportion of the pulverizer output.
Adjust the timer for a 10-min period and start the machine. For
6.3.11 In storage systems, take samples at the outlet of the
hand sieving alternative, see Appendix X3.
cyclone collector. If the sampling location is under suction,
7.3.3 At the end of the sieving period, remove the stack, slip
provide the container with a cover that can be closed before it
off the receiver pan, and carefully brush into the pan receiver
is withdrawn from the sampling connection.
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