Water softener is a commonly used process equipment for removing hardness in the raw water so as to make
it usable for various applications like boiler feed, cooling tower make up, textile mills, laundries, AC plants,
heat exchangers and for domestic use also.The water softener is a cylindrical vessel containing strong acidic cation
resins in Na form. When the hard water passes through the softener the resins exchange water hardness
( sum of calcium and magnesium ions ) and gives sodium ion to the water, that’s how one gets the soft water.
The resins has a finite exchange capacity which needs to be restored by charging the resins with Nacl.
Softner (FRP) – Capacity 10 m3/hr
The reaction can be shown as under :
CaSo4 ( raw water ) + R ( Na ) = R ( Ca ) + Na2 So4 --- Service cycle
R ( Ca ) + Nacl = R ( Na ) + Cacl2 ( drained out ) --- Regeneration cycle
The resins are generated by 10 – 13 % Nacl solution. The regeneration timing is @ 20 – 30 minutes followed by slow rinsing for 5 min. and fast rinsing for 5 – 10 min.
The softener can be in MS or FRP construction, with nest of valves or single multiport valve. The unit can be manual or automatic in operation.
The softener removes only hardness and sodium is given back to the water, hence TDS does not reduce.