1、Designation: D6543 14bD6543 15Standard Guide tothe Evaluation of Measurements Made by Online CoalAnalyzers1This standard is issued under the fixed designation D6543; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides techniques to be used for the evaluation of the measurement performance of online coal analyzers.1.2 Th
3、is standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents
4、2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sample of CoalD6518 Practice for Bias Testing a Mechanical Coal Sampling System (Withdrawn 2008)3D7430 Practice for Mechanical Sampling of CoalE1
5、78 Practice for Dealing With Outlying Observations3. Terminology3.1 DefinitionsFor additional definitions of terms used in this standard, refer to Terminology D121.3.2 Definitions:Definitions of Terms Specific to This Standard:3.2.1 analyzer system, na coal quality measurement system which includes
6、an online coal analyzer and which may includeone or more stages of a coal-sampling system.3.2.2 calibration, nmathematical modeling of analyzer and comparative coal sampling and analysis data. Factors from themodel are used in the online analyzer control software.3.2.3 full-stream analyzer, nan anal
7、yzer system that interrogates the coal on a process belt.3.2.4 Latent Variable Model, na mathematical model that can estimate each systems precision, when the analyzer iscompared to two independent reference systems.3.2.5 online analyzer, nan analytical tool consisting of an instrument and systems,
8、which together provide measurements, orestimates, or both, of coal quality parameters.3.2.6 outlier, nan extreme value that statistical tests indicate to be far enough from other results in a population underconsideration to cause suspicion that the value is not a member of the population.3.2.7 refe
9、rence material, nmaterial of stable composition that may be used to generate static analyzer measurements.3.2.8 reference system, na measurement system used to measure the characteristics of a lot of coal that are also measured byan online analyzer, and against which the online analyzer measurements
10、 are compared.3.2.9 sample stream analyzer, nan analyzer system that is fed a save or reject stream from a sampling system.3.2.10 standardization, ncalibration of an instrument to a reference material using static stability measurements.1 This guide is under the jurisdiction of ASTM Committee D05 on
11、 Coal and Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved Sept. 1, 2014Jan. 1, 2015. Published October 2014January 2015. Originally approved in 2000. Last previous edition approved in 2014 asD6543-14a.-14b. DOI: 10.1520/D6543-14b.10.1520/D6543-15.2 F
12、or referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is refer
13、enced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that u
14、sers consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.11 static stability, n
15、an estimate of the measurement precision of an instrument obtained on material that is not moving.The estimate normally is expressed as the standard deviation and average of the measurements for a given period of time.3.2.12 synchronization error, nan error that occurs from comparing measurements ma
16、de by an online analyzer and a referencesystem that are not measuring exactly the same lot because of temporal and/or spatial offsets.4. Summary of Guide4.1 This guide describes how to measure performance of an online analyzer using comparative measurements. The performanceevaluation consists of a p
17、aired comparison of analyses from a reference method using ASTM sampling, sample preparation, andanalysis methods for several lots of coal with the analyses from the online analyzer for the same lots of coal. The data resultingfrom the comparative test may be evaluated using graphical and statistica
18、l techniques outlined below.4.2 Various techniques are recommended by online analyzer manufacturers for standardization or static testing. Thesetechniques are useful for establishing a benchmark before conducting a comparative test. These techniques may also be used asdiagnostic tests in accordance
19、with methods recommended by online analyzer manufacturers and graphical and statisticaltechniques included in this guide.5. Significance and Use5.1 Online analyzers are used to provide quality data on lots of coal. The resulting quality data are used as a production toolor for some contractual appli
20、cation. This guide provides the means of evaluating the analyzer system and the data produced.5.2 Become familiar with the documents terminology and layout. The section on test design and data collection will providethe means by which all the analysis data will be gathered. The test should be carefu
21、lly designed to ensure the users requirementsare met.5.3 The procedures defined in this guide can be used to estimate the accuracy and precision of an online analyzer, (1) to conductacceptance testing following installation and (2) to monitor the accuracy and precision (a) during routine use (qualit
22、y control), (b)when significant changes are made to the analyzer, and (c) when a significant change in the coal being analyzed occurs (e.g., adifferent seam at a mine, or a new coal source at a power plant). These procedures can also be used for calibration purposes.6. Selection and Conduct of Perfo
23、rmance Evaluations6.1 Introduction:6.1.1 Several techniques can be used to evaluate the performance of an online analyzer. These techniques provide data that canbe evaluated by using the graphical and statistical methods described in Section 7 of this guide.6.1.2 At the time of installation, all of
24、the graphical and numerical methods outlined in this guide may prove useful. On a routinebasis, conducting any of the instrument stability checks and comparative evaluations that do not disrupt normal operations mayprove useful. Control charts may be applied to all the performance measures that are
25、gathered on a routine basis, including meananalysis value of reference material, RMSD, etc.6.1.3 Whenever there is a major change to the operating parameters, the configuration, the calibration, the processes, or thehardware associated with the analyzer or the reference system, the user may wish to
26、perform comparative tests. In addition tocomparative tests, standardization or static tests, or both, as recommended by the online analyzer manufacturer, may be helpful.6.1.4 Changes in coal characteristics may also impact analyzer performance. Particle size, source of coal, mining techniques,and de
27、gree of preparation, which if changed from previous test periods and which are not in the analyzer calibration database, mayaffect analyzer precision and accuracy.6.1.5 Additional changes which could merit performance testing include a change in the material or width of the conveyor, orcoal flow rat
28、es (in the case of full-flow analyzers).6.2 Static Stability Measurements for Baseline AssessmentAreference material may be used to provide a baseline assessmentof static measurement precision. The reference material may be used to compare current mean and standard deviation values withmean and stan
29、dard deviation values, previously collected in the same manner. The resulting comparative data may help determinewhether any apparent decline in analyzer dynamic performance may be attributed to a change in the operating characteristics ofthe analyzer, in the absence of the influence of sampling, pr
30、eparation, and analysis.6.2.1 The results of this evaluation can indicate whether analyzer precision has significantly degraded or whether a bias mayhave occurred. If so, it may be possible to adjust the analyzer to restore initial performance. If the user wishes only to measurecurrent static stabil
31、ity, any available coal may be used in the analysis zone of the analyzer. Note, however, that the actual standarddeviation in static stability tests might be influenced by the composition or mass of the coal being examined or analyzer factors,such as the strength of the radioactive sources used by t
32、he analyzer or condition of analyzer electronic components.6.2.2 It is essential that the length of the analysis period be defined, (for example, one minute, two minutes, or five minutes)and be constant in the static stability test. The standard deviation resulting from the static stability test dec
33、reases as the length ofthe analysis period increases.6.3 Comparison of Analyzer System to Reference System Measurements:D6543 1526.3.1 Once an analyzer installation has been completed and calibration adjustments have been made, the analyzer owner mayrequire acceptance testing. Also, the analyzer own
34、er may decide to relocate the analyzer. In these cases, comparison teststhat is,to compare the analyzer system results to conventional sampling and analysis techniqueswill provide the user calibrationverification data and/or data that could be used for recalibration of the analyzer.6.3.2 Since perfo
35、rmance evaluations usually consist of 30 or more comparisons, with each of these lasting from 30 minutes tothree hours, these comparisons may be conducted in a batch over several hours or days, or continuously throughout the operationallife of the analyzer system.6.3.3 If two independent conventiona
36、l coal-sampling and laboratory analysis measurements can be made from each of a seriesof batches of coal interrogated by the analyzer, the Latent Variable Model (LVM) can be used to provide unbiased estimates ofthe measurement precision of the analyzer and of the conventional sampling and analysis s
37、ystems.6.3.4 Any two series of measurements are independent if their measurement errors are uncorrelated. Correlation of measurementerrors can be avoided and independence assured by use of a true random selection of physical increments or samples of materialor by using different schemes and equipmen
38、t for collection, preparation, and laboratory analysis of the samples, or both. Acomplete treatment of the subject of independence of measurements and the various means of assuring independence is beyondthe scope of this guide.6.4 Sampling Considerations:6.4.1 Selection of Appropriate Sampling and S
39、ample Preparation MethodsDecisions regarding sample collection should begoverned by Practices D2234/D2234M and D7430 as appropriate. The method to be used for sample preparation should bedetermined before the beginning of increment collection. Sample preparation techniques should remain consistent (
40、see PracticeD2013). Before installation of the analyzer, consideration should be given to the ability to obtain representative samples forcomparison to analyzer measurements and the regimen for sample handling and analysis. For the use of mechanical samplingsystems, inspection (see Practice D7430, P
41、art C) and bias testing (see Practice D7430, Part D) are good methods for evaluationof the systems suitability for the test.6.4.2 Selection of Reference Sample Point(s):6.4.2.1 Comparative tests can be used to evaluate the performance of either the analyzer itself or the “analyzer system”(consisting
42、 of the analyzer and the sampling system that feeds it). The comparative evaluations of the analyzer system can be usedto determine the ability of the analyzer system to measure the characteristics of the main coal stream. The selection of the referencesystem sample point(s) determines whether the c
43、omparative tests will assess the analyzer or the analyzer system.6.4.2.2 The most direct and practical two-instrument test, when the analyzer is fed the secondary reject of a mechanicalsampling system, uses the final save to compare directly to the analyzer. A manual or mechanical sample collected f
44、rom theanalyzer discharge may provide an independent sample, which may be used to assess the performance of the analyzer (see Figs.1-3).6.4.2.3 There are instances when there is no save sample (see Fig. 4) associated with the system feeding the analyzer. In thiscase, it is possible to construct a te
45、st with several comparisons by collecting separate samples from the analyzer feed and discharge.6.4.2.4 In some instances, the discharge of the analyzer may be fed to further stages of mechanical sampling. A single stage ofsampling downstream of the analyzer is most common (see Fig. 5). In this case
46、, the secondary save will provide a convenientcomparison sample. A test of such a system that requires more than one set of comparative data might incorporate a series ofsamples (stopped belt or full stream cut) collected from the analyzer discharge or the secondary reject stream, as well. In therel
47、atively rare circumstances in which the analyzer discharge feeds two additional stages of sampling, the tertiary save isrecommended for two-instrument and bias testing, and a stopped belt or full stream cut of the secondary or tertiary rejects of theanalyzer discharge may be used as a third instrume
48、nt. Practical considerations of increment collection at the secondary rejectshould be balanced with considerations of sampling variances introduced by crushing and tertiary sampling. For two instrumentsto be independent of each other, one or both instruments must interrogate the stream of interest w
49、ithout changing the characteristicsof the stream. This may be true in some through-belt noncontacting configurations. In the case of flow-through analyzers thatFIG. 1 Key to SchematicsD6543 153FIG. 2 Analyzer on Secondary RejectThree-Stage MechanicalSamplingFIG. 3 Analyzer on Secondary RejectTwo-Stage MechanicalSamplingFIG. 4 Single-Stage Mechanical SamplingFIG. 5 Analyzer on Primary SaveTwo-Stage Mechanical Sam-plingD6543 154require a sample, the independence of systems is obtained in a case in which the primary coal stream is sampled by one instrumentbe
