Boiler Feed Water Properties and Characteristics

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bqua water treatment scheme boiler water feed make up

Boiler Feed Water Properties

Requirements for boiler feed water design and requirements include maximum tolerance levels of alkali, salt, silica, phosphates and other elements. This is in proportion to the pressure at which the boiler will be operated. These boiler water levels must be gotten from the boiler manufacturer, and are basically based on the boiler water properties.

bqua water treatment scheme boiler feed water make up

water treatment scheme for boiler feed water

Below tables are the recommended boiler feed water properties / boiler feed water chemical characteristics (levels)  taken from APAVE. Which is the Association of electrical and steam unit owners), up to pressures of 100 bar for medium steaming rates and for volumes of water in the chambers sufficient to properly control the blow down rates, and from ABMA (American Boiler Manufacturers Association) in its standard guarantee of steam purity.

Boiler Working Pressure (Bar)
0 – 20.7 20.8 – 31.0 31.1 – 41.4 41.5 – 51.7 51.8 – 62.1 62.2 – 68.9 69.0 – 103.4 103.5 – 137.9
Boiler Feed water
Dissolved oxygen (measured before oxygen scavenger addition) 0.04 0.04 0.0070 0.007 0.0070 0.007 0.007 0.007
Total Iron mg/l 0.1 0.05 0.03 0.025 0.02 0.02 0.01 0.01
Total copper 0.05 0.025 0.02 0.02 0.015 0.015 0.01 0.01
Total hardness(CaCO3) 0.3 0.3 0.20 0.2 0.1 0.05 not detectable
Non volatile TOC 1 1.0 0.5 0.5 0.5 0.20 0.2 0.2
Oily matter 1.0 1 0.50 0.5 0.50 0.2 0.2 0.2
pH at 25 7.5 – 10 7.5 – 10 7.50 – 10.0 7.50 – 10.0 7.50 – 10 8.5 – 9.5 9.0 – 9.6 9.0 – 9.6
Boiler Water
Silica mg/l 150 90 40 30 20 8 2 1
Total alkalinity (CaCO3) 350 300 250 200 150 100 not specified
Free hydroxide alkalinity CaCO3 not specified not detectable
Specific conductance at 25 without neutralization mS/cm 3500 3000 2500 2000 1500 1000 150 100
Boiler Working Pressure (Bar)
0 – 15 15 – 25 25 – 35 35 – 45 40 – 60 60 – 75 75 – 100
Boiler Feed water
Dissolved oxygen (measured before oxygen scavenger addition) mg/l 0.02 (Physical removal of dissolved oxygen)
Total hardness French degrees 0.5 0.3 0.2 0.1 0.05 0.05 0.05
Oily matter mg/l absence 0.05 0.05 0.05
pH > 8.5
Total Iron mg/l not specified 0.05 0.05 0.03
Total copper not specified 0.03 0.03 0.01
Boiler water
M alkalinity French degrees 100 80 60 40 15 10 5
P alkalinity 0.07 M 0.070 M 0.07 M 0.070 M > 0.5 M > 0.5 M > 0.5 M
SiO2 mg/l 200 150 90 40 15 10 5
TDS 4000 3000 2000 1500 500 300 100
Phosphates 30 to 100 31 to 100 20 to 80 21 to 80 10 to 60 10 to 40 5 to 20
pH 10.5 to 12 10 to 11
Make up water Softened or softened and carbonate free Demineralized