1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 2486 : 1997 Incorporat
2、ing Amendment No. 1 ICS 13.060.01; 91.140.65 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Recommendations for Treatment of water for steam boilers and water heatersBS 2486 : 1997 Issue 2, April 1998 This British Standard, having been prepared under the direction of the Heal
3、th and Environment Sector Board, was published under the authority of the Standards Board and comes into effect on 15 February 1997 BSI 1998 The following BSI references relate to the work on this standard: Committee reference CII/62 (formerly EPC/37/8) Draft for comment 95/521422 DC ISBN 0 580 2622
4、0 0 Amendments issued since publication Amd. No. Date Text affected 9948 April 1998 Indicated by a sideline in the margin Committees responsible for this British Standard The preparation of this British Standard was entrusted to Subcommittee EPC/37/8, Treatment of water for boilers, upon which the f
5、ollowing bodies were represented: Association of Circulator Manufacturers British Association for Chemical Specialities British Water Chemical Industries Association Chemical Industries Association (GOSIP) Electricity Association Health and Safety Executive Institute of Domestic Heating and Environm
6、ental Engineers Institute of Marine Engineers Institute of Plumbing Manufacturers Association of Radiators and Convectors Limited Power Generation Contractors Association PGCA (BEAMA Ltd.) Royal Society of Chemistry Safety Assessment Federation Ltd.Issue 1, April 1998 BS 2486 : 1997 BSI 1998 a Summa
7、ry of pages The following table identifies the current issue of each page. Issue 1 indicates that a page has been introduced for the first time by amendment. Subsequent issue numbers indicate an updated page. Vertical sidelining on replacement pages indicates the most recent changes (amendment, addi
8、tion, deletion). Page Issue Page Issue Front cover Inside front cover a b i ii iii iv 2 2 1 blank original original 2 original 1 2 3 4-18 19 20-40 Inside back cover Back cover 2 2 2 original 2 original original 2b blankBS 2486 : 1997 BSI 1997 i Contents Page Foreword iii Specification Section 1. Gen
9、eral 1.1 Scope 1 1.2 Objectives 1 1.3 References 1 1.4 Definitions 2 Section 2. Water quality requirements for boilers 2.1 General 3 2.2 Quality of water supply 3 2.3 Hot water systems 3 2.4 Steam generating plant 5 2.5 Sampling and testing 16 Section 3. External water treatment 3.1 Introduction 18
10、3.2 Boiler feed water treatment options 18 Section 4. Removal of gaseous impurities 4.1 General 20 4.2 Physical de-aeration 20 4.3 Chemical de-aeration 20 Section 5. Boiler water conditioning 5.1 General 22 5.2 Control of concentration of solids in boiler water 22 5.3 Prevention of corrosion 23 5.4
11、Prevention and control of deposition in boilers 27 5.5 Hideout 28 5.6 Once-through boilers 28 5.7 Method of dosing boiler water conditioning chemicals 28 Section 6. Condensate treatment and purification 6.1 Condensate treatment 30 6.2 Condensate contamination by oil 30 6.3 Condensate polishing 31 Se
12、ction 7. Corrosion and deposit control 7.1 Feed water tanks 32 7.2 Protection of feed systems 32 7.3 Protection of condensate lines 34 7.4 Corrosion in boilers 35 Section 8. Water-side protection of idle boilers 8.1 General 36 8.2 Storage overnight or for a few days but not exporting steam 36 8.3 St
13、andby and load topping boilers 36 8.4 Storage for extended periods 36BS 2486 : 1997 ii BSI 1997 Annexes A (informative) Methods of expressing concentrations of impurities in water 38 B (informative) Typical analyses of treated water 38 C (informative) Steam purity, carryover, foaming and priming 39
14、D (informative) The principal sources of contamination requiring condensate purification 40 Tables 1 Water treatment for hot water systems 5 2 Recommended water characteristics for shell boilers up to 30 bar 6 3 Recommended water characteristics for fired water tube boilers 8 4 Recommended water cha
15、racteristics for non-fired water tube boilers 12 5 Recommended water characteristics of feed water at economizer inlet for once-through boilers 13 6 Recommended water characteristics for coil boilers 14 7 Recommended water characteristics for electrode boilers 15 8 Some neutralizing amines with thei
16、r distribution ratios 30 B.1 Analyses of water treated by systems A to F 39 Figures 1 Steam boiler feed water pre-treatment options 4 2 Maximum concentrations of silica in boiler water 11 3 Conductivity of sodium nitrate solution 17 4 Variation in the concentration of dissolved oxygen in water with
17、temperature 21 5 Coordinated and congruent phosphate treatments 26 6 A well-designed feed water tank 33 List of references Inside back coverIssue 2, April 1998 BS 2486 : 1997 BSI 1998 iii 1) Or Section 35(2)(a) of the Patents Act 1949 if applicable. | | | | Foreword This British Standard was prepare
18、d by Subcommittee EPC/37/8. It revises and supersedes BS 2486 : 1978, which is withdrawn. The responsibility for this standard has now been allocated to CII/62. BS 2486 was first published in 1954 and last revised in 1978. This revision of the standard brings the technical content up to date, reflec
19、ting developments and experience gained in industrial boiler design and operation since 1978. The scope has been broadened to include water treatment for electrode boilers or evaporators, combined heat and power plant (CHP), combined cycle plant (CCP) and plant that produces hot water for heating or
20、 process purposes only. Further information on the design and manufacture of water-tube steam generators and plant can be found in BS 1113 : 1992 and that of shell boilers in BS 2790 : 1992. Further information on the maintenance of hot water systems of output 45 kW can be found in BS 6880 : Part 3
21、: 1988. Given the range of knowledge and experience of the users of this standard, descriptive and introductory text cannot be entirely eliminated. It is also necessary to provide explanations for those applications which do not fall conveniently within the tables provided, or where there are risks
22、if the treatment concerned is not adequately understood. Values for levels of water treatment chemicals given in this standard are typical values given for information only. It is strongly recommended that, for specific applications, the advice of specialists in boiler water treatment be sought and
23、followed. Wherever a pressure is quoted in terms of bar, it refers to bar (gauge). WARNING. Many of the chemicals referred to in this standard are hazardous to human health and or environment and should be handled with care. Attention is drawn to the provisions of the Control of Substances Hazardous
24、 to Health Regulations 1994 1 and applicable environmental legislation. (See note 2 to 1.1.) Attention is drawn to the fact that it is claimed that the use of methyl ethyl ketoxime is the subject of British patent No. 2 145 707, copies of which can be obtained from the Sale Branch, The Patent Office
25、, Cwmfelinfach, Cross Keys, Newport NP1 7HZ. BSI takes no position as to the validity of the patent or whether it is still in force. The patent is endorsed licences of right under Section 46 of the Patents Act 1977 1) , which states: (3) Where such an entry is made in respect of a patent a) any pers
26、on shall, at any time after the entry is made, be entitled as of right to a licence under the patent on such terms as may be settled by agreement or, in default of agreement, by the Comptroller on the application of the proprietor of the patent or the person requiring the licence. Licence details ca
27、n be obtained from the registered proprietor of the patent. 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
28、legal obligations.iv blankSection 1 Issue 2, April 1998 BS 2486 : 1997 BSI 1998 1 2) 1 bar = 100 kPA. Section 1. General | | | | | | | | | | | | | | | | | | | 1.1 Scope This British Standard gives recommendations for the control of water-side conditions of steam boilers and water heaters and also fo
29、r the preparation of feed water for such plant. The following categories of water heating or steam-raising plant are covered: a) hot water systems as defined in 1.4; b) electrode boilers; c) shell (fire-tube) boilers operating at pressures up to 30 bar; 2) d) water-tube boilers operating up to criti
30、cal pressure; e) once-through boilers, including coil and hairpin types, operating up to, or above, the critical pressure. NOTE 1. Regulation 11 of the Pressure Systems and Transportable Gas Containers Regulations, 1989 2 came into effect on 1 July 1994 and requires boiler users to provide operators
31、 with adequate and suitable instructions for the safe operation of the boiler, and to ensure that the boiler is not operated, except in accordance with these instructions. Guidance given in the Health and Safety Executives Approved Code of Practice Safety of Pressure Systems 3 requires that instruct
32、ions should cover, if appropriate, the feed water treatment. NOTE 2. The Control of Substances Hazardous to Health (COSHH) Regulations 1994 1 require an assessment of the risk of exposure to substances hazardous to health and implication of the control measures needed to prevent, or if that is not r
33、easonably practicable, adequately control such exposure. All sources of exposure in the workplace are covered including releases resulting from explosion or venting. For further information users are advised to consult the Approved Codes of Practice covering the control of substances hazardous to he
34、alth and control of carcinogenic substances 4. The recommendations are not applicable to: a) the treatment of water for most domestic heaters, which is covered by BS 7593 Code of practice for treatment of water in domestic hot water central heating systems; b) the treatment of water for marine boile
35、rs, which is covered by BS 1170 Recommendations for treatment of water for marine boilers; c) the treatment of water for nuclear-powered steam-generation plant. The use of electronic, electrostatic or magnetic products is outside the scope of this standard. The preparation of a future British Standa
36、rd covering such physical treatments of water for steam boilers and water heaters is being considered. Methods for the analysis of water are not described in this standard. Additional information on water and water treament is given in annexes A to D. 1.2 Objectives 1.2.1 Objectives of water treatme
37、nt The objectives of water treatment are: a) to contribute to the overall safety of operation of the boiler or water heater; b) to assist in the maintenance of high heat-transfer efficiency in the boiler or water heater by: 1) preventing deposition of precipitated scale or other debris; 2) preventin
38、g corrosion or deterioration of surfaces in contact with water; c) to maintain the quality of any generated steam or hot water, appropriate to the particular application. Failure to maintain suitable water conditions could compromise the in-service integrity of pressure parts and lead to danger from
39、 the unintentional release of stored energy or the scalding effect of hot water or steam. 1.2.2 Factors influencing the quality of feed water required for steam boilers and water heaters These are: a) the type and design of boiler or water heater, materials of construction and the operating conditio
40、ns, particularly heat transfer rates and pressure; b) the desired steam or hot water quality and the requirements for any spray attemperators, desuperheaters or post-boiler plant, e.g. steam turbines. Tables 1 to 7 fully reflect these criteria. 1.2.3 Factors influencing the type of water treatment n
41、ecessary to meet the feed water quality requirements These are: a) the characteristics, relative proportions and cost of make-up water, condensate and other process water that can comprise the feed water; b) the capacity and characteristics of any existing water treatment facilities and procedures;
42、c) the balance between capital and operating costs of any proposed water treatment plant or procedure, including the effect of energy costs. 1.2.4 The water treatment process The water treatment process, except for closed circuit water systems, usually involves two distinct elements: a) external tre
43、atment, which is concerned primarily with the removal of undesirable constituents; b) internal treatment, where chemical additions are made to the feed water, boiler water and steam in order to confer desirable attributes, or to react with traces of undesirable constituents which can remain after ex
44、ternal treatment.2 BSI 1998 BS 2486 : 1997 Issue 2, April 1998 Section 1 1.3 References 1.3.1 Normative references This British Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate points in the text and the
45、 cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this standard only when incorporated in the reference by amendment or revision. For undated references, the lates
46、t edition of the cited publication applies, together with any amendments. 1.3.2 Informative references This British Standard refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of the standard are listed on the inside back co
47、ver, but reference should be made to the latest editions. 1.4 Definitions For the purposes of this standard the following definitions apply: 1.4.1 boilers Items of plant which heat water to its boiling point to produce saturated steam. This steam can subsequently be superheated. 1.4.2 hot water heat
48、ers Items of plant which heat water to a temperature below its boiling point at the pressure of the system. | | | | | | | NOTE 1. The water so heated feeds a closed primary circuit utilizing some form of heat exchanger which allows the primary water to heat air, water or other process fluids. The pr
49、imary circuit water is never used for potable or domestic purposes. NOTE 2. Hot water heaters and their associated primary circuits are usually classified according to their operating temperature, as defined in 1.4.3, 1.4.4, and 1.4.5. 1.4.3 high temperature hot water (HTHW) Water above 120 C. 1.4.4 low temperature hot water (LTHW) Water below 100 C. 1.4.5 medium temperature hot water (MTHW) Water at 100 C to 120 C inclusive.Issue 2, April 1998 BS 2486 : 1997 BSI 1998 3 Section 2. Water quality requirements for boilers | | | 2.1 General The recommendati
