Iron oxide is of particular concern in today s boiler water treatment programs.
Boiler feed water hardness limit.
Note 1 recovery boilers the boiler feed water used shall be completely de mineralized and also the boiler feed water and boiler water shall be conditioned in accordance with high pressure boilers working at 60 kg cm2 and above.
It is desirable to keep the concentration of phosphates in the water to 30 50 ppm in order for complete reaction of the phosphates with the calcium hardness entering the.
131 the internal treatment is for boiler feed water and external treatment is for make up feed water and the condensate part of the system.
Feed water purity is a matter both of quantity of impurities and nature of impurities.
The treatment of boiler water can be put into two parts.
Feed water boiler water characteristics as per is 10392 1982 1 feed water parameters upto 20 kg cm2 21 kg cm2 to 39 kg cm2 40 kg cm2 to 59 kg cm2 unit total hardness 10 1 0 0 5 ppm as caco 3 ph value 8 5 9 5 8 5 9 5 8 5 9 5 dissolved oxygen.
T d s amine sio2 chloride iron fe standard 9 5 10 2 nil 5 8ppm 10 15ppm 15 30ppm 5 10ppm 1 ppm 1 ppm 01ppm.
These are internal treatment and external treatment.
Parameter control ph tds total hardnes ca.
Parameters for boiler water.
Effects if either of the values increases water will accordingly become acidic or alkaline leading to detrimental effects caused due to acidic attack or caustic embrittlement.
The purity requirements for any feed water depend on how much feed water is used as well as what the particular boiler design pressure heat transfer rate.
In order for this reaction to take place it is important to maintain a ph at a minimum value of 9 50.
Parameters for cooling tower.
Feed water treatment to avoid corrosion make up water to steam boilers should be treated with oxygen scavengers to avoid serious corrosion problems.
Some impurities such as hardness iron and silica are of more concern for example than sodium salts.
Steam boiler rating and feed water temperature boiler output and feed water.
The limits can be relaxed.
Internal treatment protects against feed water hardness by preventing.
Hardness chloride 7 3 7 8 2600 1580 800 780 300.
For boiler water ph is maintained between 11 11 8 and that of feed water between 7 9.
Maximum flow velocities in water systems water velocities in pipes and tubes should not exceed certain limits.
Deposition from low less than 1 0 ppm hardness boiler feedwater is eliminated with chelant programs and can be reduced by up to 95 by a good polymer phosphate treatment program.
A total hardness as c a co 2 mg l max.
