Boiler Feed Water Hardness Limit

A total hardness as c a co 2 mg l max.

Boiler feed water hardness limit. 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. The treatment of boiler water can be put into two parts. Maximum flow velocities in water systems water velocities in pipes and tubes should not exceed certain limits.

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. For boiler water ph is maintained between 11 11 8 and that of feed water between 7 9. Parameters ph th p al. This value will limit the silica content of the steam to 0 25 ppm as a function of selective.

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. The limits can be relaxed. 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. Feed water purity is a matter both of quantity of impurities and nature of impurities.

Parameters for boiler water. Iron oxide is of particular concern in today s boiler water treatment programs. Internal treatment protects against feed water hardness by preventing. Parameter control ph tds total hardnes ca.

These are internal treatment and external treatment. Feed water treatment to avoid corrosion make up water to steam boilers should be treated with oxygen scavengers to avoid serious corrosion problems. In order for this reaction to take place it is important to maintain a ph at a minimum value of 9 50. 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.

Phosphates are used to react with calcium hardness in the boiler water. 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. Hardness chloride 7 3 7 8 2600 1580 800 780 300. Parameters for cooling tower.