1.To reduce the boiler water saltness
If the boiler water saltness is beyond the standard, due to the increased amount of saltness carried by the steam, the steam quality declines, in order to ensure the steam quality, the interface of steam and water shall be drained continuously.
2.To drain the sediment and corrosion products in boiler water.
The residual hard scale and PO43-reaction products in boiler water and the corrosion products in the boiler of the dissolved oxygen carried by the water supply mostly accumulates at the interconnecting boxes under the water cooling wall, they shall be drained periodically.
3.Boiler blowdown will lose large amount of heat, water and chemical reagents, so the boiler water concentration shall be strictly controlled, and the boiler blowdown shall be reduced as possible.