1、INTERNATIONAL STANDARD ISO 7935 First edition 19924 2-I 5 Stationary Source emissions - Determination of the mass concentration of Sulfur dioxide - Performance characteristics of automated measuring methods Emissions de sources fixes - Determination de Ia concen tra tion en masse de dioxyde de soufr
2、e - Caractbristiques de Performance des methodes de mesurage automa tiques Reference number ISO 79357 992(E) ISO 7935:1992(E) Contents Page 1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3、. . . . . . . . . . . . . . . . . . 1 2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .* 2 3 Definitions ,. 2 4 Description of the automated measuring Systems . . . . . . . . . . . . . . . . . . 3 5
4、Numerital values of Performance characteristics and their applica bility ,*.* 4 Annexes A Determination of main Performance characteristics of automated measuring Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、 . 6 B Additional Performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 C Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 0 ISO 1992 All rights reserved. No pa
6、tt of this publication may be reproduced or utilized in any ferm or by any means, electronie or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-1 211 Geneve 20 l Switzerland Prin
7、ted in Switzerland ii ISO 7935: 1992(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member bo
8、dy interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrot
9、echnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a v
10、ote. International Standard ISO 7935 was prepared by lSO/TC 146, Air quality, Sub-Committee SC emissions. Annex A forms an integral part of this Internationa and C are for information only. Technical Committee 1, Stationary Source Standard. Annexes B ISO 7935:1992(E) Introduction Sulfur dioxide tan
11、arise in considerable quantities from combustion of fossil fuels used for energy generation, industrial activities processing Sulfur or Sulfur containing material, and from combustion of Sulfur con- taining waste. The waste gas from these processes, containing Sulfur di- Oxide, is usually discharged
12、 into the ambient atmosphere, via a duct or a chimney. For evaluating the mass concentration of Sulfur dioxide present in the waste gas of stationary Source emissions, a number of highly developed methods of integrated sampling and subsequent determination by chemi- cal analysis and automated measur
13、ing Systems are available. Considerable experience exists on their application under plant conditions. One of these methods is standardized as ISO 7934. ISO 7934 is used for example in comparative measurements, where the automated measuring methods are involved. The automated technique is capable of
14、 continuous measurement of the mass concentration of Sulfur dioxide. For methods where Performance characteristics are given, the values of Performance characteristics are used to decide whether a method is suit- able for a given measuring task (see ISO 6879:1983, clause 1). Values of the main Perfo
15、rmance characteristics of automated measuring Systems, capable of determining the mass concentration of Sulfur dioxide present in waste gas stationary emission sources, are given in clause 5. Additional Performance characteristics are given in informative annex B. The procedure for evaluating the va
16、lues of the Performance characteristics listed in clause 5, is described in normative annex A. IV INTERNATIONAL STANDARD ISO 7935:1992(E) Staticpnary Source emissions - Determination of the mass concentration of Sulfur dioxide - Performance characteristics of automated measuring methods 1 Scope This
17、 International Standard specifies a complete set of values of Performance characteristics for auto- mated measuring Systems for the continuous measurement of the mass concentrations of Sulfur dioxide in stationary Source emissions. NOTE 1 If the Performance characteristics of an auto- mated measurin
18、g System are listed according to table 1, this ensures that the automated measuring System is reliable and gives satisfactory continuous results. The set of data listed in table 1 refers to the perform- ante characteristics of measurement methods, in- cluding all Steps from sampling to recording and
19、, if necessary, storage of data. This International Standard is applicable to extractive and non-extractive automated Sulfur dioxide measur- ing methods. For both methods it implies the appli- cability of Zero and calibration gas and the availability of comparable samples. The automated measuring Sy
20、stem tan be calibrated with calibration gases, by applying the manual method described in ISO 7934, or by applying an automated measuring System pre- viously verified according to this International Stan- dard using a different principle of detection. The value of the integral Performance (3.7) is d
21、etermined by using ISO 7934 or an automated measuring System verified according to this International Standard with a different principle of detection. At present, the range over which this specification applies is between 0 g/m3 to 0,l g/m3 and 0 g/m3 to 8 g/m3 (see table 2 for details). NOTE 2 Alt
22、hough it is impossible to give precise testing details, the requirements and testing principles are also ap- plicable to non-extractive Systems. Table 1 - Main Performance characteristics Performance Numerital Test characteristics value methods (see annex A) Detection Iimit Effect of interfering sub
23、stances Response time Integral Performance ( SA 2 % 1 A.4.2.1 .l + 2 % 1) 2) A.4.2.1.2 200 s 3) A.4.2.1.3 t: 2,5 % 1) 4) A.4.2.2 1) Related to the upper limit of measurement. 2) The main interfering substances in the flue gas from combustion plants are CO*, CO, NO, H,O and, in smaller concentrations
24、, NO, and NH,. If the water va- pour is not removed from the flue gas of coal and waste fired incinerators, HCI and HN may also interfere. In special cases there may be other interfering substances (e.g. cyanide). 3) Assuming an integration time of 30 min. 4) See 3.7. The facilities at which the val
25、ues of the Performance characteristics given in table 1 have been verified ac- cording to this International Standard in the appropri- ate ranges are listed in table 2. ISO 7935:1992(E) Table 2 - Facilities and measuring ranges - Furnaces for hard coal Furnaces for hard coal with Stack gas desulfura
26、tion plant Furnaces for brown coal Furnaces for heavy fuel oil Refuse incinerator Coke oven Calcar with heavy fuel oil Sulfuric acid recovery plant I Measuring range g/m3 of SO2 1) O-l toO-8 0 to 0,l 0 - 0,l to 0 - 3,0 0 - 0,l to 0 - 5,0 0 - 0,4 to 0 - 1 ,o 0 to 1 0 to 5 0 to 1 I 1) Related to 101,3
27、 kPa, 273 K and dry gas. 1 2 Normative references The following Standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All Standards are subject to revision, and Partie
28、s to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the Standards indicated below. Members of IEC and ISO maintain registers of cur- rently valid International Standards. ISO 6879:1983, Air quality - Performance
29、 character- istics and related concepts for air quality measuring methods. ISO 7934: 1989, Stationary Source emissions - De- termination o f the mass concentration of Sulfur diox- ide - Hydrogen peroxide/barium perchlora te/Thorin me thod. 3 Definitions I Standard, the For the purposes of this Inter
30、nationa following definitions apply. 3.1 automated measuring System (AMS): A com- plete System that may be attached to a chimney to continuously measure and record the mass concen- tration of Sulfur dioxide passing through the chimney. The integral Performance defined in this subclause is an upper l
31、imiting value for the AMS. Relevant systematic errors of the measured values of the ISO manual method, or the verified AMS using a different principle of detection, have to be known and taken into account. 3.2 analyser: Analytical part in an extractive AMS. 3.3 verified AMS: AMS previously verified
32、in ISO 7935. 3.8 chimney: Stack or final exit duct on a stationary process used for the dispersion of residual process gases. 3.4 calibration gas: A gas of known and reliable 3.9 mass concentration: The concentration of a composition that may be used to check the response substance in an emission, e
33、xpressed in milligrams per of an AMS. cubic metre or grams per cubic metre. 3.5 comparative measurements: Measurements that are performed in the Same chimney in the same sampling plane for the same period of time. 3.6 manual method: The test method defined in ISO 7934 for the manual sampling and ana
34、lysis 0% stationary Source emissions containing Sulfur dioxide. 3.7 integral Performance, SA: The integral perform- ante is a measure of the working accuracy of the AMS. lt is calculated according to the formula for Standard deviations. The integral Performance is derived from the differ- ence in th
35、e pairs of measured values of Sulfur dioxide by the AMS under investigation, and by an ISO man- ual method or a verified AMS of different measuring principle on the basis of a sufficient number of com- parative measurements spread over the period of un- attended Operation (see annex A). NOTES 3 lt i
36、s not possible to determine the Standard deviation of an AMS under repeatable working conditions because - commercially available calibration gas mixtures contain- ing Sulfur dioxide do not have all the properties of actual waste gas and do not cover all possible influences; - the mass concentration
37、 of Sulfur dioxide in waste gas usually varies with time; - it is not possible to maintain the properties of a waste gas present in the waste gas flue when it is transferred into a vessel. 4 The reason that the integral Performance is defined as a measure of the working accuracy, is that it contains
38、, in addition to random errors, all the effects of interfering sub- stances, changes in temperature and power line as well as zero drifts and span drifts. lt also includes the Standard de- viation of the ISO manual method or the verified AMS using a different principle of detection, which tan be det
39、ermined separately and eliminated if necessary. Furthermore, it in- cludes the effects, for the different methods, of a different response time to variations in the composition of the waste gas. 2 3.10 stationary Source emissions: Those waste gases that have been emitted from a stationary plant or p
40、rocess and are exhausted to a chimney for dis- persion into the atmosphere. 4 Description of the automated measuring Systems 4.1 Introduction There are two types of automated measuring sys- tems: - extractive methods; - non-extractive methods, known as in-situ or Cross-duct measuring methods. Exampl
41、es of the components of these Systems are given in figures 1 and 2. Using the extractive method, the representative gas Sample is taken from the Stack with a sampling probe and conveyed to the analyser through the Sample line and Sample gas conditioning System. The values de- termined are often reco
42、rded or stored by means of electronie data processing. The non-extractive method does not require any Sample processing. In addition, it takes into consider- ation a larger part of the waste gas. Most of the methods described in 4.2 and 4.3 are able to deter- mine Sulfur dioxide specifically. Method
43、s which rely on conductometry determine total Sulfur oxides. 4.2 Extractive methods The extractive methods enable Separation of the sampling and analysis Parts, thereby facilitating main- tenance operations. The main Parts are - a Sample probe; - a Sample line; - a gas conditioning System; - an anal
44、ytical part. Certain extractive methods also include Sample di- lution. The Sample probe is placed inside the duct containing gaseous effluents. The choice of locations may sometimes be difficult, since the measurement to be made needs to be representative and calibration should be possible. The des
45、ign of the Sample probe and the gas con- ditioning System essentially depends on physico- Chemical characteristics (composition of the gaseous Phase, particle concentration, temperature, water dew Point, etc.) of the effluents to be analysed and the principle of the analyser used. Since particulate
46、matter and humidity may influence the measurement, the line contains a particulate filter and a humidity elimination device. In Order to limit Sulfur dioxide losses and inconsistent readings, the line is frequently heated. The analytical detection methods most commonly used are absorption, using inf
47、rared or ultraviolet radi- ation, fluorescence, using ultraviolet radiation, interferometry and conductometry. 4.3 Non-extractive methods For in-situ or Cross-duct methods, an Optical device is used which is positioned directly in the duct of gaseous effluents. lt consists of two modules, one being
48、a radiation emittor, the other a receptor of the radiation which has passed through the gases con- taining Sulfur dioxide. Installation of duct, depends these two modules, in on the apparatus used. relation to the The Signals from the receptor are subsequently pro- cessed, in Order to convert the da
49、ta into concen- tration, expressed as V/V or in milligrams per cubic metre. NOTE 5 When comparing the results from dry extractive methods and non-extractive methods, it is necessary to know the water content of the flue gases for correction of the in-situ value to a value on a dry gas basis. ISO 7935:1992(E) 1 2 3 4 5 6 7 8 9 10 KeY 1 2 3 4 5 6 7 8 9 IO 11 Gas sampling probe Particulate filter Heating jacket or heating bandage Cooler with condensate-separator Sampling pump Filter Needle valve Flowmeter Analyser Recorder Inlet for a) calibration gas mixtures containing Sulfur dioxide b
