1、BRITISH STANDARD BS 3407:1982 Guide for Assessing coke screening plant UDC 662.749.2:621.928:620.16BS3407:1982 The BritishStandard, having beenprepared under the directionof theSolid MineralFuels Standards Committee, waspublished underthe authorityof the BoardofBSI andcomes into effect on 31May1982
2、BSI 12-1999 First published September1961 First revision August1969 Second revision May1982 The following BSI references relate to the work on this standard: Committee reference SFC/8 Draft for comment80/53517 DC ISBN 0 580 12637 4 Cooperating organizations The Solid Fuel Standards Committee, under
3、whose direction this BritishStandard was prepared, consists of representatives from the following: Association of British Solid Fuel Appliances Manufacturers Association of Consulting Engineers British Carbonization Research Association* British Cast Iron Research Association British Ironfounders As
4、sociation Chamber of Coal Traders Chartered Institution of Building Services Coke Oven Managers Association* Combustion Engineering Association Consumer Standards Advisory Committee of BSI Council of Ironfoundry Associations Department of Energy (Energy Technology) Domestic Solid Fuel Appliances App
5、roval Scheme Electricity Supply Industry in England and Wales Health and Safety Executive Heating and Ventilating Contractors Association Institute of Energy Low Temperature Coal Distillers Association of Great Britain Ltd. National Coal Board* Society of British Gas Industries Solid Smokeless Fuels
6、 Federation Womens Solid Fuel Council The organizations marked with an asterisk in the above list were directly represented on the Technical Committee entrusted with the preparation of this BritishStandard. Amendments issued since publication Amd. No. Date of issue CommentsBS3407:1982 BSI 12-1999 i
7、Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 General 2 5 Description of methods 2 6 Provision and presentation of technical information 4 Appendix A Number of increments for moisture sample 6 Appendix B Typical report 6 Appendix C
8、Example of calculation of input data 9 Table 1 Number of increments for 1% precision 6 Publications referred to Inside back coverBS3407:1982 ii BSI 12-1999 Foreword This BritishStandard has been prepared under the direction of the Solid Mineral Fuels Standards Committee and supersedes the1969 editio
9、n, which is therefore withdrawn. The main technical change from the previous edition concerns the efficiency of screening and the opportunity has been taken to align it with BS1016-18, which has superseded BS1293 and BS2074. This standard gives guidance on the testing of new coke screening plants or
10、 plants where major alterations have been carried out, and to show the effectiveness with which the specified coke is separated into the required size fractions. In coke screening practice, the required size fractions or grades refer to coke at the outlet of storage hoppers or at the end of a boom l
11、oader or at other such points where coke is finally discharged from the plant, and therefore the tests will normally include the effect on the coke of the passage through the hopper. The procedure of sampling directly underneath the screens may be permitted as long as the fact is noted and its impli
12、cations realized. For the purposes of this standard, main screening plants are considered to consist of the screens, storage hoppers, anti-breakage devices and debreezing screens, together with inter-connecting conveyors and chutes. Mobile screening plants are those which are commonly used to remove
13、 undersize material from graded coke after ground storage. Clause4 gives guidance on methods of assessing the effectiveness with which a screen separates coke into the required sizes. Clause5 gives a description of how the test is to be carried out and clause6 some procedures for obtaining the requi
14、red technical data for evaluating the plant. Appendix A shows the number of increments to be collected for moisture determination, Appendix B sets out the way in which the results should be recorded and Appendix C gives a method for calculating input data when testing mobile plant. This standard req
15、uires frequent reference to BS1016-18 and BS1017-2 and it is based on the assumption that the relevant requirements of these standards are complied with. This standard is intended for application at coke ovens but would be equally applicable to any coke producing plant or manufactured fuel works. A
16、British Standard does not purport to include all the necessary provisions of a 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
17、front cover, an inside front cover, pagesi andii, pages1 to10, an inside back cover 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.BS3407:1982 BSI 12-1999 1 1 Scop
18、e This BritishStandard provides guidance on assessing coke screening plants, both new and those to which major alterations have been carried out, including mobile plants. It describes methods that can be used to satisfy buyer and seller that the plant is capable of meeting the requirements agreed be
19、tween them and to indicate the effectiveness of separation of the specified coke into required fractions. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this BritishStandard the following definitions app
20、ly: 3.1 Sampling terms 1) 3.1.1 sample a number of increments grouped together for analysis and testing to provide information about the unit of coke from which the increments are taken 3.1.2 subsample part of a sample when the sample has been collected in two or more parts, each part being analysed
21、 separately. Each subsample is composed of evenly-spaced increments 3.1.3 increment the quantity of coke collected by a single operation of a sampling instrument 3.2 Coke terms 1) 3.2.1 screening; screens the commercial operation of separating coke into sizes or grades, using screens for that purpos
22、e 3.2.2 sieving; sieves the laboratory or test operation of size analysis, using sieves for that purpose NOTEAll references in this standard to sieves and sieving should be interpreted as references to sieves which comply with the requirements of BS410. 3.2.3 grading see screening 3.2.4 size analysi
23、s the size characteristics of a sample of coke as determined by a laboratory sieving procedure 3.2.5 graded coke (sized coke) coke that has been separated between specified size limits by screening 3.2.6 oversize the percentage by mass of coke whose size is larger than a specified upper size limit 3
24、.2.7 undersize the percentage by mass of coke whose size is smaller than a specified lower size limit 3.2.8 large coke coke that does not pass through the largest screen in use 3.2.9 breeze coke that will pass through the smallest screen in use 3.2.10 input coke the coke fed to a commercial screen o
25、r a series of screens 3.2.11 rated input the quantity (t/h) for which a screen or series of screens is designed 3.2.12 throughput the quantity (t/h) fed to a screen or series of screens during a specified period 3.2.13 output coke or product the coke obtained from a screen or a series of screens 1)
26、When BS1017-2:1960 is revised, it is intended to adopt the terms in that revision.BS3407:1982 2 BSI 12-1999 4 General No screen is completely effective in performing its object of removing the whole of the material which is below the aperture size. Consequently, the coke that does not pass through a
27、 screen always includes some material which is below the aperture size. The proportion of such undersize may be appreciable and is likely to increase with throughput. On the other hand, the wear of a screen increases the amount of oversize in the grade below it. The screen apertures are selected, th
28、erefore, to give the desired product, allowing for the limitations of the screening operation and for breakage in the hopper. The effectiveness of such a screen to separate coke should be assessed by the ratio of the mass of coke below the desired size which passes through the screen to the total ma
29、ss of such coke. Similarly, the ability of a pair of screens to produce a grade should be assessed by the proportion of coke within the desired size limits. The different methods of assessment are as follows. 1) Efficiency. The efficiency of screening is the ratio of the mass of undersize coke passi
30、ng through the screen to the mass of such coke passing over and through the screen. 2) Performance a) The performance of a screen is the proportion by mass in the coke which has passed over a screen and is above the required size. b) The performance of a screen plant, in relation to a pair of screen
31、s, is normally the percentage by mass of the fraction in a graded coke which is between the required size limits. It is apparent that, although each approach will give an assessment of the effectiveness with which the plant is working, the results will be different. Each approach has its own applica
32、tion and it is necessary to decide which should be adopted. Thus, efficiency measures the effectiveness with which a screen removes material below the screen apertures in size. Performance, however, measures the effectiveness with which a screen or a pair of screens will produce coke of the desired
33、sizes. If interest is centred more directly on the ability of a screen to separate coke, then method1 should be used and samples taken at the outlet of the screen or at some adjacent point before the coke enters a hopper. This method may also be usefully employed to assess the choice of aperture siz
34、e to give a product of desired size. The ability of a screen or screening system to produce coke of a desired size can be assesed by method2, which is normally used for marketing control purposes. Samples will normally be taken at the dispatch loading point and the assessment may include the effect
35、of breakage on conveyors and in hoppers, and the effect of debreezing screens at hopper outlets. The results obtained from such samples will therefore assess the ability of the plant as a whole to produce coke to a given size. A combination of these methods will give a comprehensive assessment of th
36、e behaviour of the whole plant, which may be desirable for special investigations. When methods for the performance of a screen and a screen plant or a screen plant alone are followed, the results may be recorded as shown in Appendix B. 5 Description of methods 5.1 Types of plant. This standard is a
37、pplicable to the following two types of plant. a) Main screening plant. This forms a fixed unit which may be attached to a carbonization plant; it receives its input from conveyors, dispatching its output to discharge points for bulk loading, or into bunkers and thence into sacks. b) Mobile screenin
38、g plant. A mobile plant is used to remove undersize material from graded coke after ground storage or to regrade coke drawn from stock. Such a plant often consists of a receiving hopper fed by a mobile stacker, crane, mechanical shovel or similar device, and a single deck screen or multi deck screen
39、 with facilities for bulk or sack loading or both. The principles of testing these two types of plant are the same, but in actual operation some differences of practice are unavoidable; these are described as they arise. 5.2 Importance of sampling. The usefulness of the test is dependent on the coll
40、ection of satisfactory samples. It is essential to collect samples that are free from bias and are representative of the input and output coke. NOTEFor general comments on the avoidance of bias seesection6 of BS1017-2:1960. 5.3 Quality of product. The main factors that vary and affect the quality of
41、 the product are as follows: a) throughput; b) moisture content; c) bulk density; d) size distribution of input coke (which may affect the feed to each individual screen);BS3407:1982 BSI 12-1999 3 e) the height through which the coke may fall in the screening operation. The size analysis of coke fed
42、 to the plant is influenced by: 1) the type of carbonizing plant; 2) the carbonizing conditions; 3) the caking properties; 4) the size of coal carbonized. 5.4 Operation of screening plant. During the period of the test, the throughput should be at or near the rated input, but the average throughput
43、should not exceed that originally specified. NOTEAlthough the throughput to the plant should be constant the loading on the individual screens may vary. The amount of undersize in the input should not exceed that originally specified by the purchaser. The use of a coke cutter or breaker alters the s
44、ize analysis of the feed and, where one is incorporated, tests should be carried out both with and without it in operation. The screens should be cleaned at the end of each shift and the number of particles removed from each screen recorded. This does not apply to debreezing screens at hopper outlet
45、s. If it is desirable to obtain additional information about the behaviour of the screen under a range of conditions, it is necessary to carry out tests with input cokes of different size analyses and with varying throughput. 5.5 Duration of test 5.5.1 Main screening plant. Where a feed hopper prece
46、des the screening plant, the height of coke in the hopper varies throughout the period of the test. The test period should be of such duration as to cover the full range of hopper conditions that are likely to arise. It is recommended that for plants operating throughout the24h, the minimum period o
47、f test should be three days and for plants operating on day shifts only, the minimum period of test should be the working week of at least five days. 5.5.2 Mobile screening plant. In any single test, at least10t of coke should be passed on to the screen, preferably in a continuous flow. If it is pos
48、sible, the required number of increments should be collected in a single day; otherwise the test should be extended over a sufficient number of days to permit the required number of increments to be collected. The increments should be spread evenly over the loading period. 5.6 Samples required 5.6.1
49、 Main screening plant. It is necessary to collect one sample for size analysis and one for moisture determination from the input coke, and one for size analysis and one for moisture determination from the output coke from each hopper discharge point or screen. 5.6.2 Mobile screening plant. In most cases it is impracticable to obtain a sample of the input coke or to measure its throughput. Consequently, the test method recommended is such that it permits the indirect calculation of input data from an analysis of coke passing over and through the screen. It is realized that t
