1、Designation: D6543 15D6543 17Standard 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 r
2、evision. 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 Thi
3、s 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.1.3 This international s
4、tandard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. R
5、eferenced Documents2.1 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Practice for Collection of a Gross Sample of CoalD6518 Practice for Bias Testing a Mechanical Coal Sampling System (Withdrawn 2008)3D7430 Practice for Mechanical
6、 Sampling of CoalE178 Practice for Dealing With Outlying Observations3. Terminology3.1 DefinitionsFor additional definitions of terms used in this standard, refer to Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 analyzer system, na coal quality measurement system which in
7、cludes 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, n
8、an analyzer 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 sy
9、stems, 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
10、.7 reference material, nmaterial of stable composition that may be used to generate static analyzer measurements.1 This guide is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved Jan. 1, 2015June
11、 1, 2017. Published January 2015June 2017. Originally approved in 2000. Last previous edition approved in 20142015 asD6543-14b.-15. DOI: 10.1520/D6543-15.10.1520/D6543-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annu
12、al 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 referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an in
13、dication 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 users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be
14、 considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.8 reference system, na measurement system used to measure the characteristics of a lot of coal that are also measured byan online analyzer, and agai
15、nst which the online analyzer measurements 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.3.2.11 static stabili
16、ty, nan 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 measuremen
17、ts made 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 o
18、f a paired 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 stati
19、stical 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 accord
20、ance 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
21、application. 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 c
22、arefully 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 (q
23、uality 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
24、Performance 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, al
25、l of 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
26、 are 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 wis
27、h to 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,a
28、nd degree 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 flo
29、w rates (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
30、 standard 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 samplin
31、g, preparation, 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 s
32、tability, 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
33、 by the analyzer or condition of analyzer electronic components.D6543 1726.2.2 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 stab
34、ility test decreases as the length ofthe analysis period increases.6.3 Comparison of Analyzer System to Reference System Measurements:6.3.1 Once an analyzer installation has been completed and calibration adjustments have been made, the analyzer owner mayrequire acceptance testing. Also, the analyze
35、r owner 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
36、performance 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 conven
37、tional 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 analy
38、sis systems.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 equ
39、ipment 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
40、and Sample 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 consist
41、ent (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 D74
42、30, Part 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”(consi
43、sting 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
44、the comparative 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 collec
45、ted from 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
46、 a test 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
47、 case, 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 t
48、herelatively 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 theFIG. 1 Key to SchematicsD6543 173FIG. 2 Analy
49、zer 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 174analyzer discharge may be used as a third instrument. 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
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