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1、BRITISH STANDARD BS 1756-5: 1971 Incorporating Amendment No. 1 Methods for the Sampling and analysis of flue gases Part 5: Semi-routine analyses Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1756-5:1971 This British Standard, having bee
2、n approved by the Solid Fuel Industry Standards Committee, was published under the authority of the Executive Board on 27 October 1971 BSI 07-1999 First published March 1952 First revision December 1963 Second revision October 1971 The following BSI references relate to the work on this standard: Co
3、mmittee references SFE/17 and SFE/17/1 Draft for approval 70/38595 ISBN 580 06766 1 Co-operating organizations The Solid Fuel Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific
4、 and industrial organizations: The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this standard: Association of Consulting Engineer
5、sGas Council* British Cast Iron Research AssociationHeating and Ventilating Contractors British Coke Research Association*Association British Ironfounders AssociationInstitute of British Foundrymen British Mechanical Engineering Institute of Fuel* ConfederationInstitution of Gas Engineers* British S
6、teel Industry*Institution of Heating and Ventilating Chamber of Coal TradersEngineers Chemical Industries Association*Institution of Mechanical Engineers Coal Utilisation CouncilLow Temperature Coal Distillers Coke Oven Managers AssociationAssociation of Great Britain Ltd. Combustion Engineering Ass
7、ociationNational Coal Board* Council of Ironfoundry AssociationsSociety of British Gas Industries* Department of the Environment*Water-tube Boilermakers Association* Department of Trade and IndustryWomens Advisory Council on Solid Fuel Domestic Solid Fuel Appliances Approval Scheme* Electricity Coun
8、cil, the Central Electricity Generating Board and Area Boards in England and Wales* British Ceramic Research AssociationInstitution of Civil Engineers British Laboratory Ware AssociationInstitution of Electrical Engineers Cement Makers FederationIron and Steel Institute Institute of PetroleumScienti
9、fic Instrument Manufacturers Institute of Water Pollution ControlAssociation Institution of Chemical EngineersSociety of Chemical Industry Society of Glass Technology Amendments issued since publication Amd. No.Date of issueComments 7756October 1993Indicated by a sideline in the margin Licensed Copy
10、: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1756-5:1971 BSI 07-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1Introduction1 1.1Scope1 1.2Standard calibration mixtures1 2Alternative methods for carbon dioxide determina
11、tion1 2.1Constant volume (Bone and Wheeler) apparatus1 2.2Infra-red absorption1 2.3Thermal conductivity measurement2 3Alternative methods for carbon monoxide determination3 3.1Infra-red absorption3 3.2Colorimetric indicator tubes3 3.3Catalytic method using hopcalite4 4Method for total oxides of sulp
12、hur determination5 4.1Introduction5 4.2Principle5 4.3Apparatus6 4.4Reagents6 4.5Procedure6 4.6Sources of error6 Figure 1 Principle of infra-red absorption method7 Figure 2 Diagram of thermal conductivity method8 Figure 3 Carbon monoxide indicator tube9 Figure 4 Katz carbon monoxide recorder general
13、layout9 Figure 5 Katz carbon monoxide recorder system of connections enabling either silica gel tower to be used on inlet or outlet10 Figure 6 Apparatus for the determination of oxides of sulphur11 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled Copy, (c)
14、 BSI BS 1756-5:1971 ii BSI 07-1999 Foreword This standard makes reference to the following British Standards: BS 1752, Laboratory sintered or fritted filters. BS 1756, Methods for the sampling and analysis of flue gases Part 1: Methods of sampling Part 3: Analysis by the Haldane apparatus Part 4: Mi
15、scellaneous analysis. BS 3156, Methods for the analysis of fuel gases. BS 3250, Thermal testing of domestic solid fuel burning appliances with convection Part 1: Flue loss method. BS 4314, Apparatus for physical methods of gas analysis Part 1: Infra-red gas analysers for industrial use. BS 4559, The
16、 preparation of gaseous mixtures. This British Standard was first issued in 1952 as a guide to the selection of suitable procedures for the sampling and analysis of flue gases. For the purpose of this standard, “flue gas” is defined broadly as the gaseous product arising from the combustion of fuel
17、or from the combustion of any carbonaceous matter in materials being processed. The subsequent revision was extended to cover not only flue gases from domestic and industrial fuel-burning installations but also those from various industrial processes. The present edition is virtually unaltered excep
18、t for the introduction of SI units, where necessary. The sampling and analysis of a flue gas is most often required for one or more of the following purposes: 1) checking and controlling the efficiency of combustion, 2) calculating heat balances, 3) detecting air or gas inleakage, 4) determining com
19、positions and hence calculating volumes of waste gases, 5) determining moisture contents, 6) assessing the effect of the gas on other parts of the plant, e.g. corrosion or tube blockage, 7) determining substances likely to cause pollution of the atmosphere, 8) determining toxic gases. For the contro
20、l of combustion efficiency, calculation of heat balances and detecting air inleakage, the determination of carbon dioxide, carbon monoxide and oxygen covers most practical requirements. For more precise work sulphur dioxide, hydrogen and methane must be taken into account and a separate method used
21、for low concentrations of carbon monoxide. In assessing the effect of flue gases on other parts of a plant and in guarding against pollution of the atmosphere, determinations of dew-point, sulphur dioxide, sulphur trioxide and nitrogen oxides may be necessary. The revised standard has been divided i
22、nto the following parts: Part 1: Methods of sampling; Part 2: Analysis by the Orsat apparatus; Part 3: Analysis by the Haldane apparatus; Part 4: Miscellaneous determinations; Part 5: Semi-routine analyses. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled
23、Copy, (c) BSI BS 1756-5:1971 BSI 07-1999iii The standard deals with the following determinations: Carbon dioxide Oxygen Carbon monoxide Hydrogen Methane Moisture Dew-point Sulphur dioxide Sulphur trioxide Nitrogen oxides Total oxides of sulphur Except in this part, no reference has been made to mode
24、rn procedures for gas analysis by chromatographic, infra-red or other physical methods, some of which form the basis of other British Standards. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct app
25、lication. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 12, an inside back cover and a back cover. This standard has been updated (see copyright da
26、te) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 G
27、MT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1756-5:1971 BSI 07-19991 1 Introduction 1.1 Scope The methods described in this Part of this British Standard are intended for semi-routine use, particularly in the analysis of flue gases from domestic gas appliances for carbon dioxide and carbon monoxide
28、 as a criterion of combustion performance. In certain circumstances they may be used for particular determinations as alternatives to each other or to the methods already described, but the results obtained should be checked occasionally by the more precise methods given in the other Parts of this s
29、tandard. NOTEThe titles of the British Standards referred to in this standard are listed on page ii. 1.2 Standard calibration mixtures Methods for the preparation of standard samples of carbon monoxide and carbon dioxide mixtures for the calibration of the various apparatus assemblies are given in o
30、ther parts of this standard and also in BS 4559. 2 Alternative methods for carbon dioxide determination 2.1 Constant volume (Bone and Wheeler) apparatus The constant volume (Bone and Wheeler) apparatus1), by which variations in pressure, due to removal of constituents, are measured at constant volum
31、e, may be used as a less precise alternative to the Haldane apparatus. The use of the apparatus is described in standard text-books such as “Volumetric analysis” by Sutton or “Technical gas analysis” by Lunge and Ambler; a detailed description of the latest modification is given in BS 3156, to which
32、 reference should be made. 2.2 Infra-red absorption 2.2.1 Principle. Instruments are available for the determination of a number of gases by their absorption of infra-red radiation (see BS 4314). The principle of the non-dispersive instrument is illustrated by Figure 1. Radiation emitted by hot fila
33、ments passes through two analysis tubes, A and B, and falls onto two sealed receiving chambers, C and D, each of which contains a pure dry sample of the gas to be detected, in this case carbon dioxide. These receiving chambers have upper windows transparent to the wavelengths of the light being used
34、 and the lower parts of the chambers are separated by a thin diaphragm which forms a common wall between them. The gas in the receiving chamber absorbs energy at its own specific wavebands of radiation and by doing so becomes heated; hence the pressure is increased in each chamber. If the amounts of
35、 radiation absorbed by both chambers are equal, the pressure increases in both will be identical and the diaphragm will be unaffected. If a gas containing carbon dioxide is now introduced into one of the analysis tubes, say A, and pure air is in the other, some of the radiation passing through A wil
36、l be absorbed and hence less radiation will fall on C than on D. The pressure increase in D will be greater and hence the diaphragm will be displaced. The amount of radiation absorbed in tube A will be proportional to the number of molecules of carbon dioxide contained in it, i.e. to the concentrati
37、on of carbon dioxide in the gas under standard conditions; hence the reduction of radiation absorbed by C will also be proportional to the amount of carbon dioxide in the sample in A. This in turn will produce a proportional movement of the separating diaphragm between C and D and, by making this di
38、aphragm one plate of an electrical condenser, the extent of this movement can be measured electrically and the response can be used to indicate the concentration of carbon dioxide in the sample contained in A. To facilitate measurement and to reduce errors caused by slow thermal changes, the radiati
39、on beams are chopped by rotating shutters, thus producing a pulsating effect which is translated into an alternating voltage for the final measurement. The receiving chambers are sensitive only to radiation within the absorption band of the gas they contain and, unless the bands of other constituent
40、s overlap (which normally does not happen in the determination of carbon dioxide in products of combustion), the resolving power as regards a particular molecular species is complete. Carbon dioxide can be determined to an accuracy of 2 % of full scale deflection of the indicating galvanometer. 1) W
41、. J. Gooderham, Gas Analysis The determination of the major constituents of fuel gases, J. Soc. Chem. Ind., 1938, 57, 388. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:30:15 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1756-5:1971 2 BSI 07-1999 2.2.2 Calibration. The instruments need t
42、o be calibrated regularly against standard carbon dioxide mixtures. These are best obtained commercially in high pressure cylinders and should be checked by means of the Haldane apparatus (see Part 3 of this standard). Each range of a multi-range instrument should be checked with a separate mixture
43、of appropriate composition. 2.2.3 Analysis of sample. The instructions given by the maker of the instrument should be followed. A minimum of 1.5 2 litres of sample is generally required. Samples may be taken: 1) directly from the flue, 2) directly from the sampling hood, or 3) in a suitable holder,
44、as described in Part 1 of this standard, BS 3156 and BS 3250-1. Since the radiation absorption is proportional to the number of molecules in the path of the radiation, the result is dependent on the temperature and pressure of the gas in the instrument. Normal atmospheric changes do not produce a si
45、gnificant change in the result obtained, but excessive changes should be avoided. The instrument should not be placed in direct sunlight or near a heat source. Excessive pressure or suction during continuous sampling shall be avoided and a liquid seal blow-off of about 50 mm depth or an equivalent s
46、pring-loaded release valve will guard against this. Corrosive gases should not be admitted to the tubes, as these will alter the reflective nature of the surface of the tubes and so alter the calibration. Similarly, the entrance of any solid or liquid (e.g. gummy) particles should be prevented, as t
47、hese will likewise affect the calibration by settling on the wall and windows. If such particles are present in the gas sample, a particulate filter should be included. A regular maintenance, checking and leak-testing routine should be observed. During the course of time, air tends to diffuse into t
48、he detector unit and so introduce a small quantity of water vapour. This alters the absorption characteristics of the unit, making it slightly responsive to a much wider band of radiation and thereby more sensitive to traces of water vapour and impurities in the sample which would otherwise not regi
49、ster. A useful indication of the state of the detector unit can be obtained by comparing its response when the tubes are filled with air, saturated with water vapour, with the response obtained originally. The appropriate value shall be determined or obtained from the makers of the instrument. 2.3 Thermal conductivity measurement If a constant electric current is passed through a platinum wire surrounded by a gas, a point of equilibrium is reached where the electrical energy supplied to the wire is equal to the thermal energy lost