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1、CODE OF PRACTICE CP 3000:1955 The installation and maintenance of underfeed stokers UDC 66.042:662.932.85 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 BSI 02-2000 Published March 1955 ISBN 0 580
2、 34561 0 Tins CODE OF PRACTICE was prepared under arrangements entered into by the British Standards Institution and the Institution of Civil Engineers, the Institution of Mechanical Engineers and the Institution of Electrical Engineers for the preparation of Codes of Practice outside the orbit of t
3、he Council for Codes of Practice for Building (Construction and Engineering Services), established in 1942 under the gis of the Ministry of Works. In 1954 agreement was reached between the professional Institutions concerned, the British Standards Institution and the former Council for Codes of Prac
4、tice for Buildings, that a Council for Codes of Practice should be established within the British Standards Institution to be responsible for the issue of all Codes of Practice in building and in civil, electrical and mechanical engineering. Under the present constitution, a Codes of Practice Commit
5、tee for Mechanical Engineering was established, and the subject “Installation of Underfeed Stokers” was remitted to this Committee. This Code having been approved by the Solid Fuel Industry Standards Committee and the Codes of Practice Committee for Mechanical Engineering is now published by the Bri
6、tish Standards Institution under the authority of the Council for Codes of Practice. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 BSI 02-
7、2000i Contents Page Code committee convened by the institution of mechanical engineers and the British Standards Institutionii Introduction1 Section 1. General 101Scope1 102Exchange of information1 Section 2. Design considerations 201Boiler room1 202Fuel storage1 203Flues and chimneys2 Section 3. In
8、stallation 301Stokers other than those used for horizontal shell-type boilers with internal circular flues4 302Stokers designed for horizontal shell-type boilers with internal circular flues5 Section 4. Automatic safety controls 401Automatic safety controls6 Section 5. Care and maintenance 501Care a
9、nd maintenance6 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 ii BSI 02-2000 Code committee convened by the institution of mechanical engineers and the British Standards Institution This Code of
10、Practice represents a standard of good practice and therefore takes the form of recommendations. Compliance with it does not confer immunity from relevant legal requirements, including bye-laws. S. M. Mitchell (Chairman) Nominated by W. Kitson, M.I.MECH.E., M.I.E.E., M.INST.F., MEM.A.S.M.E.Instituti
11、on of Mechanical Engineers A. E. Powell, A.M.I.C.E., M.I.MECH.E. E. L. Tinley, M.I.MECH.E., F.INST.F. S. W. Barnes, M.INST.F., A.M.INST.B.E. W. Charles, M.INST.F., M.I.H.V.E.British Standards Institution S. M. Mitchell, M.I.MECH.E. Co-opted members G. T. Blackwood, A.M.INST.B.E., A.M.I.W.Association
12、 of Shell Boilermakers F. A. Glidewell, M.INST.F. DRAFTING COMMITTEE FOR THE CODE As above. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 7 and a back cover. This standard has been updated (see copyright date) and may have had amendments in
13、corporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 BSI 02-20001 Introduction This Code of Practice supersedes Appen
14、dix A, “General recommendations on installation and maintenance”, of BS 749, “Underfeed stokers (ram or screw type)”. Reference should be made to that standard for the specified requirements of such stokers and for information on suitable fuels. In Figure 1 to Figure 4, drawings of suitable boiler-r
15、oom layout are given. These should be regarded as typical diagrams only; they are not intended to be to scale. In addition to the recommendations made in this Code, reference should be made to the Factories Act and to the regulations regarding electrical equipment of the Institution of Electrical En
16、gineers. Section 1. General 101 Scope The Code offers guidance in the installation and maintenance of underfeed stokers (ram and screw types)1) for use with the following types of boilers: Domestic hot water supply Sectional cast iron or steel Vertical and horizontal shell Small water-tube. 102 Exch
17、ange of information Attention is drawn to the need for early consultation between the architect and the engineer concerned on the layout of the boiler room and its location in relation to the remainder of the building. Section 2. Design considerations 201 Boiler room The layout of the boiler room sh
18、ould receive very careful consideration. It is strongly recommended that a competent engineer should be consulted at the design stage of the building. The location of the boiler room in relation to the remainder of the building is of importance, with reasonable access for adequate fuel supply, fuel
19、store, disposal of ash, and the servicing of the stoker or stokers. The position of the chimney should also be considered at this stage. The boiler room should have adequate permanent air supply for combustion and natural ventilation should be arranged. Floor drainage should be provided. Should the
20、boiler room be under or adjacent to other rooms some form of sound and fire insulation may be necessary. 202 Fuel storage The fuel should be stored under cover and, where possible, the store should be capable of holding sufficient fuel for at least three weeks normal supply. In calculating the size
21、of the fuel store, 45 lb of coal should be allowed for each cubic foot of effective space. Means for draining the store should be provided. Accessibility of the fuel to the boiler is very important for automatic stoking and the fuel store or bunker can often be arranged above the level of the stoker
22、s to allow fuel to gravitate to the stoker hopper. Where fuel can be fed by gravity into the stoker hopper the chute or the sloping sides of the fuel store should be at an angle of at least 50 to the horizontal. It is recommended that the chute connecting the bunker to the stoker hopper should have
23、smooth internal surfaces and adequate area to ensure free flow. It should be fitted with a gate to isolate the main fuel store. The slope of the chute should be not less than 50 to the horizontal. Certain types of underfeed stoker are designed to draw fuel directly from the bunker. For vertical boil
24、ers, cast-iron and steel sectional boilers, the floor level of the bunker can be the same as the boiler house, but for horizontal shell-type boilers where the centre line of the furnace is above boiler house floor level, the floor level of the bunker should be correspondingly higher. Particular care
25、 should be given to the location and number of delivery openings into an underground store to ensure that the bulk of the coal will fall over the stoker pickup. Access to the bunker should also be provided, preferably from the boiler room. Ventilation should be arranged from the outside of the build
26、ing. Typical layouts are given in Figure 1, Figure 2, Figure 3 and Figure 4; these will be found satisfactory for the types of boiler illustrated. Where mechanical means of handling the fuel are being considered, specialist advice should be obtained on storage and the plant. 1) BS 749, “Underfeed st
27、okers (ram or screw type)” Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 2 BSI 02-2000 203 Flues and chimneys A good flue is just as necessary with an underfeed stoker as with hand firing and ade
28、quate area should be allowed for carrying away the products of combustion. The height of the chimney will need to comply with local bye-laws and will depend on the type of boiler and the draught loss through the system; in general a suction of 0.15 to 0.2 in. w.g. over the fire is required with exis
29、ting designs of stoker and the draught system should be designed accordingly. In some cases it may be desirable to control the draught by installing a draught stabilizer. All air leaks through joints, cracks, etc., will tend to reduce the draught, and flues and chimneys should be tightly sealed with
30、 allowance made for expansion and contraction. NOTEAs stated in the Introduction, these drawings are typical diagrams only and are not intended to be to scale. Attention is drawn to paragraph 7 of Section 301, which states that if a stoker is installed in a pit, the latter should be long enough to p
31、ermit withdrawal of the feed screw or ram, and sufficiently wide and deep to permit free access to the machine for cleaning and adjustments. Figure 1 Fuel bunker at ground level with boiler house below. Hopper-type stoker Figure 2 Fuel bunker and boiler house at ground level. Hopper-type or bunker f
32、eed stoker Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 BSI 02-20003 For a brick chimney it is recommended that a firebrick lining should be provided and this should be continued to a height of
33、not less than 15 ft above the entry of the flue gases, the height to be related to the temperature of the gases. A round or square section chimney is recommended and it should be as near to the perpendicular as possible, sharp bends being avoided. In connecting the boiler to the vertical chimney the
34、 horizontal length of the flue or flues should be as short as possible. Smoke pipes should not project beyond the inside surface of the chimney. Smoke pipe bends and flues should be provided with adequate access for cleaning, and an ample cleaning door should be fitted at the base of the chimney for
35、 the removal of soot. It is recommended in the interests of safety, where two or more boilers discharge into the same chimney, that explosion doors should be provided. The chimney should project above the top of the building roof ridge or above the top of any adjacent building. Failure to observe th
36、is point is often the cause of a down draught in the chimney. NOTEAs stated in the Introduction, these drawings are typical diagrams only and are not intended to be to scale. Attention is drawn to paragraph 7 of Section 301, which states that if a stoker is installed in a pit, the latter should be l
37、ong enough to permit withdrawal of the feed screw or ram, and sufficiently wide and deep to permit free access to the machine for cleaning and adjustments. Figure 3 Fuel bunker and boiler house below ground level, with bunker feed stoker in pit Figure 4 Fuel bunker and boiler house at ground level.
38、Bunker feed stoker applied at back of boiler Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 4 BSI 02-2000 If the chimney is capped with a pot, this should be of the same cross-sectional area as th
39、e chimney; if capped with a cowl, this should be of such a height above the top of the chimney as to provide a circumferential outlet of area equal to twice the cross-sectional area of the chimney. Section 3. Installation 301 Stokers other than those used for horizontal shell-type boilers with inter
40、nal circular flues Where the provision of new boilers is being considered, the height of any base for the boiler should be arranged in conjunction with the stoker manufacturer. Care should be taken that the height and volume of the combustion chamber above the level of the stoker retort are sufficie
41、nt to ensure that combustion is completed before the gases enter the boiler passes, thus preventing emission of smoke. The height of the combustion chamber above the top of the retort will depend on several factors, such as the particular make of stoker used, the class of coal to be burnt, and the t
42、ype of boiler to be fired. Since the Code covers stokers suitable for numerous designs of boiler and with a wide range of capacities it is not possible to lay down hard and fast rules for the height of the chamber in each case. For a stoker with a retort area based on the minimum sizes given by the
43、formulae in Clause 8 a) of BS 749 the height obtained from Figure 5 is recommended as a minimum. Figure 5 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 03:29:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CP 3000 1955 BSI 02-20005 The volume of the combustion c
44、hamber determines the heat release, measured in British thermal units per cubic foot per hour, and the permissible maximum heat release will depend to some extent on the nature of the setting. Where the combustion chamber walls are constructed of firebricks with no water cooling, as in the case of s
45、ome water-tube boilers, it is recommended that the heat release should not exceed 60 000 B.t.u. per cubic foot per hour, so as to limit brickwork maintenance. Where sectional heating and hot water boilers are used, the design of the majority of these allows for a large combustion chamber volume abov
46、e the firebar level, with a heat release of 40 000 to 60 000 B.t.u. per cubic foot, and this is satisfactory for stoker firing. With vertical shell-type boilers and locomotive-type boilers these ratings may be increased, provided the height from the top of the retort to the entrance to the boiler tu
47、bes is sufficient. The combustion chamber volume should be measured in cubic feet and should be the net space available for combustion after all brick linings are installed and before the gases pass into or around tubes or flues. For stokers which have to be installed under existing boilers it may b
48、e necessary to raise the boiler or to excavate a pit for the stoker in order to obtain sufficient height and volume of combustion chamber. The method to be followed will depend upon site conditions and in some instances it may be desirable to limit the height of the chamber at the expense of efficie
49、ncy, in order to minimize the modifications to the existing plant. A very large number of existing boilers are, of course, suitable for the installation of stokers without any modification to the setting of the boiler, and in such cases the stoker can be set on floor level. A suitable foundation should be provided for the stoker, to prevent any distortion of the machine during operation. The feed tube and air duct should be above floor level wherever possible. If the stoker is installed in a pit, the latter should be long enough to per