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1、BRITISH STANDARD BS 3407:1982 Guide for Assessing coke screening plant UDC 662.749.2:621.928:620.16 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 The British Standard, having been prepared under the direction of the Solid Mine
2、ral Fuels Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 May 1982 BSI 12-1999 First published September 1961 First revision August 1969 Second revision May 1982 The following BSI references relate to the work on this standard: Committee referen
3、ce SFC/8 Draft for comment 80/53517 DC ISBN 0 580 12637 4 Cooperating organizations The Solid Fuel Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Association of British Solid Fuel Appliances Manufacturers Association of
4、Consulting Engineers British Carbonization Research Association* British Cast Iron Research Association British Ironfounders Association Chamber of Coal Traders Chartered Institution of Building Services Coke Oven Managers Association* Combustion Engineering Association Consumer Standards Advisory C
5、ommittee of BSI Council of Ironfoundry Associations Department of Energy (Energy Technology) Domestic Solid Fuel Appliances Approval Scheme Electricity Supply Industry in England and Wales Health and Safety Executive Heating and Ventilating Contractors Association Institute of Energy Low Temperature
6、 Coal Distillers Association of Great Britain Ltd. National Coal Board* Society of British Gas Industries Solid Smokeless Fuels 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 pre
7、paration of this British Standard. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 BSI 12-1999i Contents Page Cooperating organizationsInside front cover Foreword
8、ii 1Scope1 2References1 3Definitions1 4General2 5Description of methods2 6Provision and presentation of technical information4 Appendix A Number of increments for moisture sample6 Appendix B Typical report6 Appendix C Example of calculation of input data9 Table 1 Number of increments for 1 % precisi
9、on6 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 ii BSI 12-1999 Foreword This British Standard has been prepared under the direction of the Solid Mineral Fuels Standards Committee and
10、 supersedes the 1969 edition, 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 BS 1016-18, which has superseded BS 1293 and BS 2074. This standard gives guidance on the testing o
11、f new coke screening plants or 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 hop
12、pers or at the end of a boom loader 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 t
13、he fact is noted and its implications 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 whi
14、ch are commonly used to remove undersize material from graded coke after ground storage. Clause 4 gives guidance on methods of assessing the effectiveness with which a screen separates coke into the required sizes. Clause 5 gives a description of how the test is to be carried out and clause 6 some p
15、rocedures for obtaining the required 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 testin
16、g mobile plant. This standard requires frequent reference to BS 1016-18 and BS 1017-2 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 p
17、lant or manufactured fuel works. A 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
18、of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 10, 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
19、 cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 BSI 12-19991 1 Scope This British Standard provides guidance on assessing coke screening plants, both new and those to which major alterations have been carried out, includ
20、ing mobile plants. It describes methods that can be used to satisfy buyer and seller that the plant is capable of meeting the requirements agreed between them and to indicate the effectiveness of separation of the specified coke into required fractions. 2 References The titles of the publications re
21、ferred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this British Standard the following definitions apply: 3.1 Sampling terms1) 3.1.1 sample a number of increments grouped together for analysis and testing to provide information about the unit of coke fr
22、om 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 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 i
23、nstrument 3.2 Coke terms1) 3.2.1 screening; screens the commercial operation of separating coke into sizes or grades, using screens for that purpose 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 an
24、d sieving should be interpreted as references to sieves which comply with the requirements of BS 410. 3.2.3 grading see screening 3.2.4 size analysis 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 separat
25、ed 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 3.2.7 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 t
26、he 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 or 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
27、 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) When BS 1017-2:1960 is revised, it is intended to adopt the terms in that revision. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+
28、00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 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 screen always includes some material whic
29、h 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, therefore, to give the desired product, allo
30、wing 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 mass of such coke. Similarly, the ability of
31、 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 passing through the screen to the mass of such
32、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 screens, is normally the percentage by mass of t
33、he 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 application and it is necessary to decide which s
34、hould 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 sizes. If interest is centred more directl
35、y on the ability of a screen to separate coke, then method 1 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 size to give a product of desired size. The
36、ability of a screen or screening system to produce coke of a desired size can be assesed by method 2, 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 of breakage on conveyors and in hoppers,
37、 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 the behaviour of the whole plant, which ma
38、y 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 applicable to the following two types of
39、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 screening plant. A mobile plant is used to remov
40、e 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 with facilities for bulk or sack loadin
41、g 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 collection of satisfactory samples. It is es
42、sential 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 see section 6 of BS 1017-2:1960. 5.3 Quality of product. The main factors that vary and affect the quality of the product are as follows: a) throu
43、ghput; b) moisture content; c) bulk density; d) size distribution of input coke (which may affect the feed to each individual screen); Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:35:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3407:1982 BSI 12-19993 e) the height through which the
44、coke may fall in the screening operation. The size analysis of coke fed 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 throu
45、ghput should be at or near the rated input, but the average throughput 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 speci
46、fied by the purchaser. The use of a coke cutter or breaker alters the size 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 scre
47、en recorded. This does not apply to debreezing screens at hopper outlets. 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
48、 Duration of test 5.5.1 Main screening plant. Where a feed hopper precedes 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 recomm
49、ended that for plants operating throughout the 24 h, the minimum period of 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 least 10 t of coke should be passed on to the screen, preferably in a continuous flow. If it is possible, 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 colle