BS 2486:1978

Foreword
Cooperating organizations
Recommendations
Section one. General
1 Scope
2 References
3 Definitions
Section two. Water quality
4 Objectives of water treatment
5 Natural impurities in water supplies
6 Methods of expressing concentrations of
       impurities in water
6.1 Description of impurities
6.2 Concentration in terms of calcium carbonate
6.3 Electrical conductivity
7 Effects of water impurities in boiler feed water
8 Recommended feed and boiler water characteristics
8.1 Introduction
8.2 Shell boilers
8.3 Water-tube boilers
8.4 Once-through boilers
8.5 Sampling and testing
9 Effect on required water quality of boiler plant
       design and operating conditions
9.1 Introduction
9.2 Feed system and economizer
9.3 Boiler
9.4 Superheater
9.5 Turbine
9.6 Condensate system
10 Control of concentration of solids in boiler
       water
10.1 General
10.2 Continuous blowdown
10.3 Intermittent blowdown
10.4 Calculation of blowdown
11 Steam purity, carryover, foaming and priming
11.1 Steam purity and carryover
11.2 Foaming
11.3 Priming
11.4 Antifoams
12 A guide to treatment selection
12.1 Water quality
12.2 Influence of condensate return
12.3 Methods of treatment
12.4 Conditioning treatment of boiler water
Section three. Internal treatment of water in boilers
13 Introduction
14 Prevention of scale formation
14.1 Carbonate control
14.2 Phosphate control
15 Prevention of corrosion
Section four. External water treatment
16 Introduction
17 Clarification
17.1 General
17.2 Sedimentation
17.3 Coagulation and flocculation
17.4 Removal of colour and organic matter
17.5 Filtration
17.6 Removal of iron and manganese by filtration
18 Precipitation softening
18.1 Removal of hardness
18.2 Effect on dissolved solids
18.3 'After-precipitation' in lime and lime/soda
       treatment
18.4 Sludge blanket process
18.5 Sludge recirculation
18.6 Coagulants and flocculants
18.7 Effect on soluble silica
18.8 Hot lime and lime/soda treatment
18.9 'Pellet reactor' lime softening or 'Spiractor'
       process
18.10 Combined precipitation and other treatment
       processes
19 Treatment by ion exchange
19.1 Introduction
19.2 Types of ion exchange
19.3 Physical form of ion exchange resins
19.4 Resin capacity
19.5 Quality of treated water
19.6 Ion exchange treatment processes
19.7 Summary of types and combinations of ion exchange
       treatment processes
19.8 Fixed bed and continuous ion exchange
       regeneration
19.9 Organic fouling of anion resins
20 Partial demineralization of brackish water
20.1 Applications
20.2 Practical operating ranges
20.3 Electrodialysis
20.4 Reverse osmosis
Section five. Condensate purification
21 Introduction
22 Condensate polishing
23 Condensate contamination by cooling water
24 Condensate contamination by oil
25 Condensate formed as a by-product in industrial
       processes
Section six. Removal of gaseous impurities by physical
             deaeration
26 Deaeration
27 Physical deaeration
Section seven. Conditioning treatment of boiler water
28 Introduction
29 Treatment to keep scale-forming impurities in
       solution
30 Treatment to keep scale-forming impurities non-
       adherent
30.1 Introduction
30.2 Phosphate conditioning
30.3 Carbonate conditioning
30.4 Physical conditioning
31 Treatment to remove dissolved oxygen
Section eight. Corrosion and deposits
32 Protection of feed systems
32.1 Introduction
32.2 Deposition: causes and remedies
32.3 Corrosion: causes and remedies
32.4 Erosion: causes and remedies
33 Protection of condensate lines
33.1 Corrosion: causes and remedies
33.2 Treatment
34 Corrosion in boilers
34.1 Introduction
34.2 Principles of treatment
34.3 Caustic cracking
35 Hideout
36 Protection of idle boilers
36.1 Introduction
36.2 Storage overnight or for a few days
36.3 Storage for extended periods
37 Boiler cleaning
37.1 Introduction
37.2 Manual cleaning
37.3 Mechanical cleaning
37.4 Chemical cleaning
Appendices
A Glossary of terms
B pH value, acidity and alkalinity
C Hardness: alkaline and non-alkaline
D Chemical reactions of salts of iron and aluminium
       as coagulants
E Chemical reactions and calculations for
       precipitation softening
F Chemical reactions in ion exchange treatment
G Operating and regenerating efficiency of ion
       exchange resins
Tables
1 Some impurities found in feed water and the
       difficulties they cause in boiler plant
2 Recommended water characteristics for shell
       boilers
3 Recommended water characteristics for water-tube
       boilers
4 Recommended water characteristics for once-
       through boilers
5 Summary of types of ion exchange treatments
6 Typical analyses of treated water
7 Types of deposits and cleaning solutions
Figures
1 Variation of electrical conductivity of pure
       water with temperature
2 Variation of electrical conductivity of water
       with concentration of sodium chloride
3 Maximum concentration of silica in boiler water
4 Variation of specific volume of steam with
       pressure
5 Continuous and intermittent blowdown
6 Reduction in solubility of (a) calcium carbonate
       by excess sodium carbonate and (b) magnesium
       hydroxide by excess sodium hydroxide
7 General arrangement for fixed bed ion exchange
       unit
8 Lime softening and sodium ion exchange
9 Dealkalization and softening by ion exchange
10 Split stream dealkalization and softening by ion
       exchange
11 Two-stage demineralization using weak base anion
       exchange resin
12 Two-stage demineralization using intermediate
       base anion exchange resin
13 Two-stage demineralization using strong base
       anion exchange resin
14 Regeneration sequence of mixed bed ion exchange
       unit
15 Continuous ion exchange
16 Electrodialysis pack
17 Reverse osmosis cell
18 Solubility of dissolved oxygen
19 Protection of feed systems
20 Congruent phosphate and coordinated phosphate
       treatments
21 Effect of mineral acidity on pH value
22 Effect of bicarbonate alkalinity and carbon
       dioxide on pH value
23 Effect of carbonate, bicarbonate and hydroxide on
       pH value
24 Concentration distributions through an ion
       exchange resin bed