1、BRITISH STANDARD BS1016-108.6: 1992 Methods for Analysis and testing of coal and coke Part 108: Tests special to coke Section 108.6 Determination of critical air blast valueBS1016-108.6:1992 This BritishStandard, having been prepared under the directionof the Solid Mineral Fuels Standards Policy Com
2、mittee, was published underthe authority of the Standards Board and comes intoeffect on 15July1992 BSI12-1999 The following BSI references relate to the work on this standard: Committee referenceSFC/3 Draft for comment92/50163DC ISBN 0 580 20902 4 Committees responsible for this British Standard The
3、 preparation of this BritishStandard was entrusted by the Solid Mineral Fuels Standards Policy Committee (SFC/-) to Technical CommitteeSFC/3, upon which the following bodies were represented: British Cement Association British Coal Corporation British Gas plc British Steel Industry Electricity Indus
4、try in United Kingdom GAMBICA (BEAMA Ltd.) Institute of Petroleum Power Generation Contractors Association (BEAMA Ltd.) Amendments issued since publication Amd. No. Date CommentsBS1016-108.6:1992 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Introduction 1 1 Sco
5、pe 1 2 References 1 3 Definition 1 4 Principle 1 5 Apparatus 1 6 Preparation of test sample 2 7 Procedure 4 8 Expression of results 4 9 Precision 4 10 Test report 5 Figure 1 Heating element 1 Figure 2 Alternative assemblies for measuring air flow 3 Figure 3 Alternative assemblies of dome and combust
6、ion chamber 3 List of references Inside back coverBS1016-108.6:1992 ii BSI 12-1999 Foreword This Section of BS1016 has been prepared under the direction of the Solid Mineral Fuels Standards Policy Committee. Part108 is a revision of the1980 edition of BS1016-13, which is withdrawn. This Section supe
7、rsedes clause9 inBS1016-13:1980, to which it is technically equivalent and which is deleted by amendment. Part108 is a further Part numbered under a scheme for rationalizing and restructuring BS1016. The new series, when complete, will begin with Part100, which will include a general introduction. T
8、he earlier series of Parts is as follows, with the new Part numbers (which will be given to revisions when they are published) in parentheses. Part 1: Total moisture of coal; (Part101) Part 2: Total moisture of coke; (Part102) Part 6: Ultimate analysis of coal; (Part106) Part 7: Ultimate analysis of
9、 coke; (Part106) Part 8: Chlorine in coal and coke; (Part106) Part 9: Phosphorus in coal and coke; (Part106) Part 10: Arsenic in coal and coke; (Part106) Part 11: Forms of sulphur in coal; (Part106) Part 14: Analysis of coal ash and coke ash; (Part114) Part 15: Fusibility of coal ash and coke ash; (
10、Part113) Part 16: Methods for reporting results; (Part100) Part 17: Size analysis of coal; (Part109) Part 18: Size analysis of coke; (Part110) Part 20: Determination of Hardgrove grindability index of hard coal;(Part112) Part 21: Determination of moisture-holding capacity of hard coal. (Part103) The
11、 following Parts in the new series have been published. Part 104: Proximate analysis; Part 105: Determination of calorific value; Part 107: Caking and swelling properties of coal; Part 108: Tests special to coke; Part 111: Determination of abrasion index of coal. Part 108 is divided into six Section
12、s as follows. Section 108.1: Determination of shatter indices; Section 108.2: Determination of Micum and Irsid indices; Section 108.3: Determination of bulk density (small container); Section 108.4: Determination of bulk density (large container); Section 108.5: Determination of density and porosity
13、; Section 108.6: Determination of critical air blast value. There is no corresponding InternationalStandard for this Section of BS1016. WARNING. This BritishStandard does not necessarily detail all the precautions necessary to comply with the requirements of the Health and Safety at Worketc. Act1974
14、1 or the Control of Substances Hazardous to Health Regulations 19882. Attention should be paid to any appropriate precautions and the method should be operated only by trained personnel.BS1016-108.6:1992 BSI 12-1999 iii A British Standard does not purport to include all the necessary provisions of a
15、 contract. Users of British Standards are responsible for their correct application. 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, pagesi to iv, pages1to6, an inside back co
16、ver and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS1016-108.6:1992 BSI 12-1999 1 0 Introduction The critical air blast value is a measure of the reactivi
17、ty of coke to air. The more reactive the coke the lower is its critical air blast value. Typical values are0.4l/min for low temperature coke and1.8l/min for high temperature coke. 1 Scope This Section of BS1016 describes a method for the determination of the critical air blast value of coke. 2 Refer
18、ences 2.1 Normative references This Section of BS1016 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on the inside back cover. Subsequent amendments to, or
19、 revisions of, any of these publications apply to this Section of BS1016 only when incorporated in it by updating or revision. 2.2 Informative references This Section of BS1016 refers to other publications that provide information or guidance. Editions of these publications current at the time of is
20、sue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definition For the purposes of this Section of BS1016 the following definition applies. critical air blast value the minimum rate of air flow through ignited, closely graded coke, in a be
21、d of specified dimensions, which will maintain combustion 4 Principle A bed of graded coke is ignited electrically in a specified combustion chamber, with dry air passing through the bed at a rate of4.25l/min. When the coke is fully ignited the rate of air flow is reduced to a preselected value for2
22、0min and then raised to the original value to attempt resuscitation. This procedure is repeated with fresh portions of the coke and with other rates of air flow until the critical value is found. 5 Apparatus 5.1 Combustion chamber, comprising a tube of transparent silica or heat-resisting glass of l
23、ength200mm, inside diameter40mm1mm and wall thickness1mm to2mm. The inside of the wall of the tube shall have three projections around the circumference, produced by reshaping the glass or by fusing-on lugs, at a distance of35mm to41mm from one end. A continuous line shall be marked round the circum
24、ference at a distance of10mm to12mm from the same end. The tube shall be closed at the other end by a rubber stopper which carries a silica or heat-resisting glass tube, of inside diameter5mm to6mm, bent at right angles. 5.2 Metal gauze disc, made from wire mesh, of aperture size0.4mm to0.6mm, to fi
25、t inside the combustion chamber and rest on the projections. 5.3 Heating element (seeFigure 1), comprising a heating wire, wound round silica rods which are held in a cylindrical frame. Figure 1 Heating elementBS1016-108.6:1992 2 BSI 12-1999 The cylindrical frame shall be made of an insulating and h
26、eat-resisting material, with outside diameter50mm, inside diameter39mm and height20mm. It shall be recessed on the underside so as to rest on the top of the combustion chamber. The diameter of this recess shall be1mm to4mm greater than the outside diameter of the combustion chamber. The top of the f
27、rame shall be recessed to a diameter of approximately46mm and to a depth of3mm. This recess shall be fitted with a porcelain or quartz disc with at least50 holes of diameter not greater than2mm and not less than0.5mm. Five silica rods, with outside diameter2.5mm 0.25mm, shall be fitted into holes dr
28、illed through the walls of the frame. The heating wire shall be of0.3mm nickel-chromium resistance wire, welded at its ends to1mm leads of the same alloy. It shall be wound helically round, and supported by, the five silica rods in the frame. The resistance of the wire (when new), as measured betwee
29、n the leads, which shall not exceed50mm in length, shall be not greater than407 and not less than 307. 5.4 Air supply, capable of providing an air flow through the combustion chamber of up to4.25l/min, controlled to within 0.05l/min. Air supplied either from a cylinder of compressed air or direct fr
30、om a compressor is suitable. NOTEIf the air is supplied from a compressor, a large reservoir should be included in the supply line to damp out pulsations and, if necessary, a filter should be included to remove oil mist. The rate of air flow through the apparatus should be controlled by a needle val
31、ve or screw clip placed after some form of pressure regulator such as a water seal (up to300mm deep) or a gas governor. 5.5 Air flow measurement system, comprising one of the following. a) Two flowmeters, one capable of measuring flow rates up to3l/min to an accuracy of 0.03l/min and the other to re
32、ad4.25l/min to the same accuracy seeFigure 2a). b) An inclined capillary flow gauge, a gas meter indicating2.5litres per revolution and a suitable manometer seeFigure 2b). 5.6 Dome, comprising one of the following. a) A dome of heat-resisting glass, of inside diameter75mm 15mm and height190mm 10mm s
33、eeFigure 3a). b) A tube, of similar material and dimensions, closed at its upper end with a rubber stopper carrying the air inlet tube seeFigure 3b). In either case the lower end shall be closed with a rubber stopper, carrying a pair of3mm diameter brass or copper leads which are connected to the le
34、ads of the heating element when the apparatus is assembled. In the case of5.6 a), the stopper shall also be fitted with the air inlet tube. 5.7 Drying tower, of diameter50mm and height300mm, with the outlet tube filled with self-indicating silica gel. 5.8 Funnel, for charging the coke, made by rolli
35、ng a sheet of paper or metal foil into a cone with an outlet at the apex of about10mm in diameter. 5.9 Former, of cork, felt-covered wood or aluminium, of a diameter slightly less than that of the combustion chamber. 5.10 Test sieves, of nominal aperture sizes1.18mm and6004m, conforming to BS410:198
36、6. 5.11 Air oven, capable of maintaining a temperature within the range105 C to110 C. 6 Preparation of test sample Prepare a test sample, in accordance withA.5 of BS1017-2:1960, which passes the1.18mm test sieve(5.10) and is retained on the6004m test sieve. Dry the test sample in a shallow tray in t
37、he oven(5.11) at a temperature within the range105 C to110 C and re-sieve it on the6004m test sieve immediately before use.BS1016-108.6:1992 BSI 12-1999 3 Figure 2 Alternative assemblies for measuring air flow Figure 3 Alternative assemblies of dome and combustion chamberBS1016-108.6:1992 4 BSI 12-1
38、999 7 Procedure Assemble the air flow measurement system(5.5) and the drying tower(5.7), as shown in Figure 2, and connect them to the air supply(5.4). Assemble the combustion chamber(5.1) and the metal gauze disc(5.2) as shown in Figure 3. Prepare the coke bed by pouring coke from the test sample (
39、clause6) through the funnel(5.8) on to the metal gauze disc. Move the funnel around during this operation so as to form a loose, uniformly packed bed. The height of the funnel above the coke bed shall be such that the free fall of the particles does not exceed5mm. Fill the combustion chamber with co
40、ke up to the line. Smooth the surface of the bed with the former(5.9), manipulated so as to roll the particles over the surface rather than to press them in position. Assemble and connect the remaining apparatus, including the heating element(5.3) and the dome(5.6), as shown in Figure 2 and Figure 3
41、, and then check for leaks. Set the rate of air flow to4.25l/min, switch on the current and adjust it so that the heat dissipated is between175W and185W. Continue heating until the glowing zone has spread to all parts of the periphery of the bed surface. At the instant this is achieved, switch off t
42、he current and reduce the air flow rate to a value which is expected to be slightly above critical value 1) , at the same time noting the reading of the relevant flowmeter or the initial reading of the gas meter, as appropriate (see5.5). Continue passing air at this rate for20min, read the gas meter
43、 again, if applicable, and increase the rate to4.25l/min. Continue at this rate until resuscitation (as indicated by the continuation or the reappearance of the glow) occurs or for a maximum of20min. NOTEObservations are made easier by screening the combustion chamber from direct lighting. If resusc
44、itation takes place, repeat the operations described above using progressively lower air flow rates, with a fresh portion of the test sample for each new rate, until a rate is found from which no resuscitation occurs. Similarly, if resuscitation does not take place, repeat the sequence of operations
45、 using progressively higher air flow rates until resuscitation just occurs. In this way, obtain two rates of air flow which differ by not more than0.06l/min and are such that resuscitation occurs from one but not from the other. Record the air flow rate from which resuscitation occurs. 8 Expression
46、of results The critical air blast value of the coke, expressed inl/min of dry air at a temperature of15 C and a pressure of100kPa, is given by one of the following formulae. a) For an air flow rate measured by a flowmeter: b) For an air flow rate measured by a gas meter: Report the result to the nea
47、rest0.01l/min. 9 Precision 9.1 Repeatability The results of duplicate determinations, carried out at different times in the same laboratory by the same operator with the same apparatus using representative portions taken from the same test sample, should not differ by more than0.06l/min. 9.2 Reprodu
48、cibility The means of the results of duplicate determinations, carried out in each of two different laboratories using representative portions taken from the same sample after the final stage of samplepreparation, should not differ by more than0.06l/min. 1) A rough estimate of the critical air blast
49、 value can be obtained from the time required for ignition (seeBrewin, W. and J.K. Thompson. Fuel in Science and Practice,1937,16,361365)3. where d is the diameter of the combustion chamber (inmm); P is the atmospheric pressure (inkPa); V is the minimum rate of air flow from which resuscitation occurs (inl/min); T is the air temperature (in C); f is the gas meter correction factor; a is the manometer pressure (inkPa); h is the aqueous vapour pressure at T w C (inkPa); T w is the temp
