ASTM D6646-01
(Test Method)Standard Test Method for Determination of the Accelerated Hydrogen Sulfide Breakthrough Capacity of Granular and Pelletized Activated Carbon
Standard Test Method for Determination of the Accelerated Hydrogen Sulfide Breakthrough Capacity of Granular and Pelletized Activated Carbon
SCOPE
1.1 This test method is intended to evaluate the performance of virgin, newly impregnated or in-service, granular or pelletized activated carbon for the removal of hydrogen sulfide from an air stream. A humidified air stream containing 1 % (by volume) hydrogen sulfide is passed through a carbon bed until 50 ppm breakthrough of H2S is observed. The H2S adsorption capacity of the carbon per unit volume at 99.5 % removal efficiency (g H2S/cm3 carbon) is then calculated. This test is not necessarily applicable to non-carbon adsorptive materials.
1.2 This standard as written is applicable only to granular and pelletized activated carbons with mean particle diameters (MPD) less than 2.5 mm. See paragraph 5.3 if activated carbons with larger MPDs are to be tested.
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: D 6646 – 01
Standard Test Method for
Determination of the Accelerated Hydrogen Sulfide
Breakthrough Capacity of Granular and Pelletized Activated
Carbon
This standard is issued under the fixed designation D 6646; 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 concentration of hydrogen sulfide in the effluent gas reaches 50
ppmv.
1.1 This test method is intended to evaluate the performance
of virgin, newly impregnated or in-service, granular or pellet-
5. Significance and Use
ized activated carbon for the removal of hydrogen sulfide from
5.1 This method was developed to compare the performance
an air stream. A humidified air stream containing 1 % (by
of granular or pelletized activated carbons used in odor control
volume) hydrogen sulfide is passed through a carbon bed until
applications, such as sewage treatment plants, pump stations,
50 ppm breakthrough of H S is observed. The H S adsorption
2 2
etc. The method is a means of determining the relative
capacity of the carbon per unit volume at 99.5 % removal
breakthrough performance of activated carbon for removing
efficiency (g H S/cm carbon) is then calculated. This test is
hydrogen sulfide from a humidified gas stream. Other organic
not necessarily applicable to non-carbon adsorptive materials.
contaminants present in field operations may affect the H S
1.2 This standard as written is applicable only to granular
breakthrough capacity of the carbon; these are not addressed by
and pelletized activated carbons with mean particle diameters
this test. It is unlikely that this test will exactly simulate actual
(MPD) less than 2.5 mm. See paragraph 5.3 if activated
conditions encountered in an odor control application, and it is
carbons with larger MPDs are to be tested.
therefore meant only as a relative comparison method.
1.3 This standard does not purport to address all of the
5.2 This test does not duplicate conditions that an adsorber
safety concerns, if any, associated with its use. It is the
would encounter in practical service. The mass transfer zone in
responsibility of the user of this standard to establish appro-
the 23 cm column used in this test is proportionally much
priate safety and health practices and determine the applica-
larger than that in the typical bed used in industrial applica-
bility of regulatory limitations prior to use.
tions. This difference favors a carbon that functions more
2. Referenced Documents rapidly for removal of H S over a carbon with slower kinetics.
Also, the 1 % H S challenge gas concentration used here
2.1 ASTM Standards:
engenders a significant temperature rise in the carbon bed. This
D 2652 Definition of Terms Relating to Activated Carbon
effect may also differentiate between carbons in a way that is
D 2854 Determination of Apparent Density of Activated
2 not reflected in the conditions of practical service.
Carbon
5.3 This standard as written is applicable only to granular
D 2867 Test For Moisture in Activated Carbon
3 and pelletized activated carbons with mean particle diameters
E 300 Practice for Sampling Industrial Chemicals
less than 2.5 mm. Application of this standard to activated
3. Terminology carbons with mean particle diameters (MPD) greater than 2.5
mm will require a larger diameter adsorption column. The ratio
3.1 Terms relating to this standard are defined in D 2652.
of column inside diameter to MPD should be greater than 10 in
4. Summary of Test Method
order to avoid wall effects. In these cases it is suggested that
bed superficial velocity and contact time be held invariant at
4.1 Breakthrough capacity is determined by passing a
the conditions specified in this standard (4.77 cm/sec and 4.8
stream of humidified air containing 1 volume % hydrogen
sec). Although not covered by this standard, data obtained from
sulfide through a sample of granular or pelletized activated
these tests may be reported as in paragraph 12 along with
carbon of known volume under specified conditions until the
additional information about column diameter, volume of
carbon, and volumetric flow rate used.
This test method is under the jurisdiction of ASTM Committee D28 on
5.4 For pelletized carbons, it is felt that the equivalent
Activated Carbon and is the direct responsibility of Subcommittee D28.04 on Gas
spherical diameter of the pellet is the most suitable parameter
Phase Evaluation Tests.
for determining the appropriate adsorption column inside
Current edition approved April 10, 2001. Published July 2001.
Annual Book of ASTM Standards, Vol 15.01.
diameter. The equivalent spherical diameter is calculated
Annual Book of ASTM Standards, Vol 15.05.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6646
according to the following equation.
3 XdXh
D 5 (1)
eqv
d 1 2 Xh
where:
d = the diameter, and
h = the length of the pellet in mm.
An average of 50 to 100 measurements is recommended to
determine the average length of a pellet. Annex A3 is a table to
guide the user in selecting bed diameter and flow rates from
typical equivalent diameters (or MPD) of pelletized carbon.
6. Apparatus and Materials
6.1 (561) % Hydrogen Sulfide in Nitrogen Mixture. The
concentration of hydrogen sulfide in the gas test mixture must
be known. It is recommended that gas cylinders specifically
manufactured for holding hydrogen sulfide gas be used. Ana-
lyzed and certified hydrogen sulfide in nitrogen gas mixtures
can be purchased from specialty gas suppliers. Annex A1 and
Annex A2 present methods that may be used to check the
hydrogen sulfide concentration of hydrogen sulfide/nitrogen
gas mixtures. It is recommended that the hydrogen sulfide
concentration be checked if gas cylinders are stored for more
than three months, particularly after being partially depleted.
Other organic contaminants that may be present in the hydro-
gen sulfide tank can affect the adsorption capacity of the carbon
being tested.
6.2 Hydrogen Sulfide Detector. The hydrogen sulfide detec-
tor used in this test must be demonstrated to reliably detect 50
ppm hydrogen sulfide in a humidified air stream. In addition to
certain “solid state” detectors, electrochemical type hydrogen
sulfide sensors, e.g., Ecolyzer Model 6400 or Interscan LD-17,
have been evaluated and fit this requirement. Other means of
hydrogen sulfide detection may be selected, as long as they are
carefully calibrated and evaluated for this application.
FIG. 1 Schematic of Adsorption Tube
6.3 Adsorption Tube. The adsorption tube is shown in Fig. 1.
Adsorption tubes are not commercially available; however,
(see Annex A3 for guide to airflow for tubes used for particles
they can be custom fabricated by a scientific glassblower. The
>2.5 mm MPD)
perforated support shown is necessary to support the carbon
6.8 Two Metering Valves. Suitable valves are the Whitey
bed and to enhance diffusion of the gases. (Adjust dimensions
SS-21-RS4 (H S/N ) and B-21-RS4 (air). Other similar valves
2 2
accordingly from Annex A3, specifically diameter.)
may be used. If the rotameters in 6.4 and 6.5 are equipped with
6.4 Flowmeter (0-500 mL/min Nitrogen; see Annex A3 for
their own high quality metering valves, these valves are not
Guide to Higher Flow Range for Particles > 2.5 mm MPD).
needed.
For hydrogen sulfide/N control, it is recommended that the
6.9 Source of Dry, Contaminant-Free Air Capable of Deliv-
wettable parts of this flow meter be made of PTFE or other
ering up to 2 liters/min Through the Test System (higher flow
corrosion resistant material. Rotameter floats should be made
for larger particles, >2.5 mm MPD, see Table A3.2.)
from non-metallic materials such as glass or sapphire.
6.10 Gas Bubbler. (Ace Glass cat .#5516 gas washing bottle
6.5 Flowmeter (0-2000 mL/min Air; see Annex A3 for
equipped with gas dispersion fritted tube, cat. #7202, porosity
Guide to Higher Flow Range for Particles > 2.5 mm MPD).
code “C”, or equivalent to this.) The glass bubbler should be
NOTE 1—Mass flow controllers have been found to be more reliable immersed in a constant temperature bath regulated at 25°C to
than flowmeters and are highly recommended due to their ability to
ensure the generation of a 80 % RH air stream for the final gas
automatically maintain precise gas flow rates. Rotameters are satisfactory
mixture (after mixing with dry H S/N ). The porous bubbler
2 2
for this method, but may require more frequent attention in maintaining
should be immersed under at least 3 inches of water to
proper test gas flows for the duration of the test.
consistently saturate the air stream with water during the
6.6 Two Stage Cylinder Regulator, Suitable for Corrosive
course of the test. (A larger gas washing bottle should be used
Gas Service, for Hydrogen Sulfide Gas Cylinder.
if larger particles than 2.5 mm (Equivalent Diameter) and a
6.7 Air Line Pressure Regulator—Low Pressure. To main- larger bed are used. Increase size proportionately with air
tain up to 10 psig pressure for up to 2 liters of air/min flow rate flow).
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6646
6.11 Hydrogen Sulfide Calibration Gas Mixture,20to50 included on the MSDS. First aid procedures for contact with a
ppmv, in nitrogen, to be used as a span or calibration gas for the chemical are also listed on its MSDS. The MSDS for each
hydrogen sulfide detector. (Available from specialty gas supply reagent may be obtained from the manufacturer.
companies.) 7.3 Safety and health hazard information on reagents used
6.12 Timer. A count up timer that can be tripped at the 50 in this procedure may also be obtained from:
ppmv set point of the H S monitor and is capable of retaining 7.3.1 Sax’s Dangerous Properties of Industrial Materials /
the tripped time. Richard J. Lewis, Sr., New York : J. Wiley, 2000.
6.13 Vibratory Feeder (see ASTM D 2854). 7.3.2 NIOSH/OSHA Pocket Guide to Chemical Hazards,
6.14 Powder Funnel. 1997, U.S. Department of Labor, Occupational Safety and
6.15 Temperature Controlled Water Bath to maintain the Health Administration, Washington, D.C. Available from U.S.
water bubbler at 25°C 6 2°C. Government Printing Office, Washington, D.C. or at http://
6.16 Other miscellaneous hardware needed to set up the www.cdc.gov/niosh/npg/npg.html.
apparatus in Fig. 2. Polyethylene tubing is suitable for carrying
8. Sampling
the H S/N flow. Clamped ball and socket joints are convenient
2 2
8.1 Guidance in sampling granular activated carbon is given
for quick connect and disconnect of the absorption column and
in recommended Practice E 300.
calibration bubbler (see Annex A2) from the system.
9. Calibration
7. Safety Precautions
9.1 Calibration of flowmeters, mass flow controllers, and
7.1 Several potential hazards are associated with conducting
hydrogen sulfide detectors shall be performed by standard
this test procedure. It is not the purpose of this standard to
laboratory methods.
address all potential health and safety hazards encountered
NOTE 2—The test apparatus (Fig. 1) has metering valves at the
with its use. The user is responsible for establishing appropri-
rotameter outlets. This is done to minimize changes in gas flow rates
ate health and safety practices before use of this test procedure.
caused by small backpressure changes during this long duration test.
Determine the applicability of Federal and State regulations
However, placement of metering valves in this position invalidates the
before attempting to use this standard test method.
atmospheric pressure calibration usually supplied by the rotameter manu-
7.2 Personnel conducting the hydrogen sulfide adsorption facturer. The apparatus in A2.4.2 may be used to calibrate the rotameters.
During this calibration, the gas delivery pressure must be the same as that
capacity procedure should be aware of potential safety and
used during the actual test.
health hazards associated with the chemicals used in this
procedure. The “Material Safety Data Sheet” (MSDS) for each 9.2 Determine the percent H S in the H S/nitrogen tank
2 2
reagent listed in Section 6 should be read and understood. using the methods outlined in Annex A1 or Annex A2 if the
Special precautions to be taken during use of each reagent are H S/nitrogen tank was not certified by the manufacturer.
FIG. 2 Schematic of Apparatus for Determination of H S Breakthrough Capacity
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6646
10. Procedure sample. A minimum of one replicate analyses must be per-
formed.
10.1 Assemble the test apparatus as shown in the schematic
diagram of Fig. 2.
11. Calculation
10.2 Adjust the H S/N and air flow rates to generate a
2 2
11.1 Calculate the hydrogen sulfide breakthrough capacity
1.0 % H S stream at a total flow rate of 1450 cm /min at the
of the test sample using the following equation:
one-inch diameter adsorption tube (see Annex A3 for higher
flowrates with larger than 2.5 mm (Equivalent Diameter) gH S
5 (2)
particles). This adjustment will depend on the concentration of
cm GAC
H S in the H S/N gas mixture.
2 2 2
C 1 L 1 mole 34.1gH S
3 F 3 T 3 3 3
10.3 Determine the H S concentration of the actual mixed S D S 3D S D S D
2 100 22.4 L mole
1000 cm
test gas using method(s) as outlined in Annex A1 or Annex A2
V
of this procedure. This test should be repeated if any adjust-
where:
ment is made on the flow meter(s).
C = concentration of hydrogen sulfide in air stream, vol-
10.4 Obtain a representative sample of the as-received
ume %,
granular or pelletized activated carbon to be tested. A 300 cm
F = total H S/air flow rate, cm /min (should be 1450
sample is sufficient for apparent density, moisture and replicate 2
cm /min) (Adjust from Annex A3 if necessary),
performance testing. (A larger amount should be used if the
T = time to 50 ppmv breakthrough, minutes, and
particles larger than 2.5 mm (Equivalent Diameter) and a larger
V = actual volume of the carbon bed in the absorption tube,
diameter bed are used).
cm (Adjust from Annex A3 if necessary).
10.5 Reduce the sample size to an aliquot for testin
...
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