1、Designation: D 6831 05aStandard Test Method forSampling and Determining Particulate Matter in Stack GasesUsing an In-Stack, Inertial Microbalance1This standard is issued under the fixed designation D 6831; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, the year of last 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 describes the procedures for determin-ing the mass concentration
3、of particulate matter in gaseousstreams using an automated, in-stack test method. This method,an in-situ, inertial microbalance, is based on inertial massmeasurement using a hollow tube oscillator. This method isdescribes the design of the apparatus, operating procedure, andthe quality control proce
4、dures required to obtain the levels ofprecision and accuracy stated.1.2 This method is suitable for collecting and measuringfilterable particulate matter concentrations in the ranges 0.2mg/m3and above taken in effluent ducts and stacks.1.3 This test method may be used for calibration of auto-mated m
5、onitoring systems (AMS). If the emission gas containsunstable, reactive, or semi-volatile substances, the measure-ment will depend on the filtration temperature, and this method(and other in-stack methods) may be more applicable thanout-stack methods for the calibration of automated monitoringsystem
6、s.1.4 This test method can be employed in sources having gastemperature up to 200C and having gas velocities from 3 to 27m/s.1.5 This test method includes a description of equipmentand methods to be used for obtaining and analyzing samplesand a description of the procedure used for calculating there
7、sults.1.6 Stack temperatures limitation for this test method isapproximately 200C 392F.1.7 This test method may be also be limited from use insampling gas streams that contain fluoride, or other reactivespecies having the potential to react with or within the sampletrain.1.8 This standard does not p
8、urport to address 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:2
9、D 1356 Terminology Relating to Atmospheric Samplingand AnalysisD 3154 Test Method Average Velocity in a Duct (Pitot TubeMethod)D 3685/D 3685M Test Methods for Sampling and Determi-nation of Particulate Matter in Stack GasesD 3796 Practice for Calibration of Type S Pitot TubesD 6331 Test Method for D
10、etermination of Mass Concentra-tion of Particulate Matter from Stationary Sources at LowConcentrations (Manual Gravimetric Method)3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D 1356.3.2 Definition of terms specific to this standard:3.2.1 particulate matter
11、for solid particles of any shape,structure, or density dispersed in the gas phase at flue gastemperature and pressure conditions.3.2.1.1 DiscussionIn accordance with the described testmethod, all material that may be collected by filtration underspecified conditions and that remains upstream of the
12、filter andon the filter after drying under specified conditions are consid-ered to be particulate matter. For the purposes of this testmethod, particulate matter is defined by gas borne matter (solidor liquid) captured on or in the filter after drying and weighingin accordance with this test method.
13、3.2.2 in-stack, inertial microbalancea mechanical oscilla-tor constructed of a hollow tube of a specific metal alloy andfitted with a filter cartridge that is designed to oscillate at afrequency that is proportional to the mass of the hollow tubeoscillator plus the mass of its filter cartridge.3.2.3
14、 mass transducerthe mass transducer is a principlecomponent of an in-stack inertial, microbalance. The masstransducer provides the mechanical structure to support andcontain the hollow tube oscillator and to support the sampleinlet nozzle fixture, source gas temperature thermocouple, and1This test m
15、ethod is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved October 1, 2005. Published October 2005. Originallyapproved in 2002. Last previous edition approved in 2005
16、as D 6831 - 05.2For 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 Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor
17、 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.s-type Pitot tube assembly. Refer to 6.1.1 for a detaileddescription of this component.3.2.4 articulating elbowa mechanical component thatmay be integrated into the sample probe just before the endconnector attaching to the mass tr
18、ansducer. This elbow is usedcontrol the angle of the mass transducer relative to the sampleprobe during insertion of the probe and mass transducer intothe stack and while positioning the mass transducer inlet nozzleinto the gas stream.3.2.5 filtration temperaturethe temperature of thesampled gas imm
19、ediately downstream of the filter cartridge.3.2.5.1 DiscussionThe temperature of the filter cartridgeis maintained at the desired temperature by controlling thetemperature of the mass transducer case and cap.3.2.6 sampling linethe line in the sampling plane alongwhich the sampling points are located
20、 bounded by the innerduct wall.3.2.7 sampling planethe plane normal to the centerline ofthe duct at the sampling position.3.2.8 sampling pointthe specific position on a samplingline at which a sample is extracted.3.2.9 weighing control proceduresquality control proce-dures used for verifying the cal
21、ibration constant for the hollowtube oscillator.3.2.9.1 DiscussionUnlike test methods such as D 6331 orD 3685/D 3685M, this method does not rely on weighingsample media in a laboratory before and after a test isconducted. The method includes an integrated filter dryingmechanism to desiccate the samp
22、le collection media in-situimmediately prior to and following each test run. No physicalhandling of sample collection media takes place prior to thestart of a test run through final filter analysis for the test run.Consequently, control filters typically used to characterize theimpact of filter/samp
23、le handling and transportation are notrequired with this method.4. Summary of Test Method4.1 The in-stack, inertial microbalance method involves theuse of a filter cartridge affixed at one end of a hollow tubeoscillator that is housed in a mass transducer housing. Themass transducer is attached to t
24、he end of an integrated sampleprobe and inserted through a port into the stack or duct. Asample is withdrawn isokinetically from the gas stream anddirected through the filter cartridge attached to the end of thehollow tube oscillator. Captured particulate matter and anycaptured moisture is weighed c
25、ontinuously as the sample gasespass through the filter cartridge and hollow tube oscillator.Sample gases then continue through the heated probe andumbilical assemblies and into a gas conditioning/control mod-ule where the collected gas sample volume is determined. Acalibrated, orifice-based flow met
26、er is used to measure thesample gas volume. In sources where the particulate mattercharacteristics can result in significant quantity of particulatematter to be trapped on the inlet nozzle walls during sampling,the trapped particulate matter can be recovered after samplinghas been completed using a
27、properly sized brush to detach andrecover trapped particulate matter from the inlet walls.4.1.1 DiscussionThe ability of this mass measurementtechnique to precisely quantify the mass of the filter andcollected particulate matter by correlating mass change to ameasured frequency change of the hollow
28、tube oscillator ispredicated on the isolation of the oscillator from externalvibration sources. To remove the potential for external vibra-tion to interfere with the measurement process, the masstransducer housing must be sufficiently massive so that anyenergy that it absorbs from external vibration
29、s will result in themass transducer case oscillating at a resonant frequency that ismuch lower the hollow tube oscillator. As a result, a massivehousing will absorb any external vibrations and prevent thosevibrations from affecting the resonance of the hollow tubeoscillator.4.2 The filter media typi
30、cally used is PTFE coated glassfiber filter media (TX-40 or equivalent) although other filtermedia can be used if desired. The filter media is mounted in aspecially designed filter cartridge housing that is designed topromote a constant face velocity through the entire surface ofthe filter. The junc
31、tion of the oscillating element and the baseof the filter cartridge is designed to ensure a leak free union.4.3 The sample gases are dried using a selectively perme-able membrane dryer followed by silica gel before the samplevolume is measured. An integrated computer-controlled feed-back system is u
32、sed to control the sample flow rate based onstack gas temperature, velocity and gas density measurements,or user input data, to automatically maintain isokinetic sam-pling conditions.4.4 To account for source gas density (molecular weight)inputs to set the isokinetic sampling conditions, the user ha
33、s theoption to use manually input data acquired using an Orsatanalyzer and moisture determination apparatus or equivalentmethod or data supplied by an on-board carbon dioxideanalyzer, oxygen analyzer and moisture measurement system.4.5 Valid measurements can be achieved only when:4.5.1 The gas strea
34、m in the duct at the sampling plane has asufficiently steady and identified velocity, a sufficient tempera-ture and pressure, and a sufficiently homogeneous composi-tion;4.5.2 The flow of the gas is parallel to the centerline of theduct across the whole sampling plane;4.5.3 Sampling is carried out w
35、ithout disturbance of the gasstream, using a sharp edged nozzle facing into the stream;4.5.4 Isokinetic sampling conditions are maintainedthroughout the test within 610 %;4.5.5 Samples are taken at a pre-selected number of statedpositions in the sampling plane to obtain a representativesample for a
36、non-uniform distribution of particulate matter inthe duct or stack.4.5.6 The sampling train is designed and operated to avoidcondensation and to be leak free;4.5.7 Dust deposits upstream of the filter are recovered ortaken into account, or both; andD 6831 05a24.5.8 The sampling and weighing procedur
37、es include desic-cation of the filter immediately before and after each test run isconducted.5. Significance and Use5.1 The measurement of particulate matter is widely per-formed to characterize emissions from stationary sources interms of total emission rates to the atmosphere for regulatorypurpose
38、s.5.2 This test method is particularly well suited for use inperformance assessment and optimization of particulate mattercontrol systems, continuous particulate matter emissions moni-toring systems and the measurement of low concentrationparticulate matter laden gas streams in the range of 0.2 mg/m
39、3to 50 mg/m3.6. System Description6.1 Major ComponentsThe in-stack, inertial microbal-ance measurement system is comprised of five major compo-nents that are listed in the following table.Mass Transducer(see 6.1.1)An assembly that houses the sample filter andinertial microbalance. Also contains the
40、Pitot tube assembly,stack gas temperature thermocouple, sample inlet nozzleand mass transducer heaters.Sample Probe andProbe Extensions(see 6.1.2)A heated support conduit for mass transducer, sampleand purge flow lines; electrical supplies for masstransducer and probe heaters; mass transducer electr
41、icalsignal cables; and the pivoting elbow used for positioningthe mass transducer into the source gas flow.SamplePneumatic/ElectricalUmbilical Cables(see 6.1.3)A heated, flexible tubing bundle that contains thepneumatic lines for transporting the sample and purgegases from/to the mass transducer; an
42、d the electricalsupply and signal cabling.Control Unit(see 6.1.4)A unit that contains sample and purge supply flowsensors and controllers; stack gas velocity pressure andtemperature transducers; sample and purge supplypressure and temperature transducers, data acquisitionand instrument control syste
43、ms; sample and purge gasconditioners; heater relays; and optionally, CO2,O2andmoisture measurement systems comprising the real-timemolecular weight measurement system.Pump / Power Unit(see 6.1.5)Contains the sample vacuum and purge supply pumpsand the 24 VDC power supply transformer for the 24VDC he
44、aters in the probe and mass transducer.A block diagram of the major components of an in-stack,inertial microbalance system is shown in Fig. 1.6.1.1 Mass TransducerThe mass transducer houses thehollow tube oscillator that is the main component of the inertialmicrobalance. The mass transducer can also
45、 serve as thesupport structure for the S-type Pitot tube assembly and athermocouple that are used for measuring stack gas velocityand temperature, respectively. A filter cartridge is mounted atthe end of the hollow tube oscillator. As sample gas is drawnthrough the filter, particulate matter is trap
46、ped on the filter andremoved from the sample gas stream. The trapped particulatematter on the filter cartridge causes the oscillation frequency ofthe hollow tube oscillator/filter cartridge system to change. Thefrequency is converted to a electronic signal that is transmittedto an analog to digital
47、frequency converter. The frequency isconverted to mass by appropriate computerized calculationsoftware. The firmware computes the mass from the measuredfrequency approximately once every three seconds. The deter-mination of mass from the measured frequency is shown belowin Eq 1 and is detailed in Eq
48、 2-6.f25 K0/ M (1)where:f = oscillation frequency of the hollow tube oscillatorK0= calibration constant for the hollow tube oscillator, andM = mass of filter and collected particulate matterThe mass transducer also combines components for measur-ing stack gas temperature and velocity, and to provide
49、 clean,dry air to desiccate the filter before and after sampling. Thecomponents and features of the mass transducer are describedin 6.1.1.1-6.1.1.4.6.1.1.1 Main Flow Inlet NozzleThe main flow inlet nozzleis exchangeable to allow sampling over a wide range of sourcegas velocity conditions (3 m/s - 27 m/s). Recommended arenozzles having inside diameter ranging from 1.5875 mm0.0625 in. to 3.1750 mm 0.125 in. to allow isokineticsampling over a range of gas velocity conditions from 3 to 27m/s. The nozzles are constructed of seamless 316 stainless steeland are design
