Split-stream softening

Acid breakthrough (split-stream softening, dealk/DI). Failure to neutralize results in acid corrosion of feed system... 

Although deaerators provide the primary means of mechanical deaeration, they are not of themselves immune from corrosive attack. Acid condensate (or MU water that has been subjected to split-stream softening or dealkalization and remains acid due to a lack of pH adjustment) can damage the deaerator. 

Hot Lime Zeolite-Split Stream Softening. Many raw waters softened by the first two processes would contain more sodium bicarbonate than is acceptable for boder feedwater purposes. Sodium bicarbonate will decompose in (lie boiler water to give caustic soda. Caustic soda in high concentrations is corrosive and promotes foaming. The American Boiler Manufacturers Association has adopted the standard that the alkalinity content should not exceed 20% of the total solids of the boiler water. Split stream softening provides a means for reducing the alkalinity content. 

Demineralization, like the zeolite process, involves ion exchange. The metal ions are replaced with hydrogen ions by means of the process and equipment described for the hydrogcn-zcolitc system (see Hot Lime Zeolite—Split Stream Softening, previously described). In addition, the salt anions (bicarbonate, carbonate, sulfate and chloride) are replaced by... 

The raw water obtained softened by both processes contain more sodium bicarbonate than acceptable for boiler feedwater. The alkalinity content should not exceed more than 20% of total solids. The alkalinity is reduced by a split stream softening process. 

Dealkalization/softening by SAC(H)/BX/blend/Degassing This process is very suitable for water sources of variable hardness and alkalinity levels and ratios. It passes a portion of the RW through the SAC (H) and the balance through a BX (the process is called split-stream dealkalization and softening). The first vessel removes all cations, producing mineral acidity, while the BX replaces all... 

Split stream make up softening. Low capital investment. High annual operating costs due to the high chemical requirments. Rapid changes in make up water quality may be difficult to accommodate. 

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