Softener system

We have discussed about Demin Plant in the last article, still remember right? Well softener is actually one type of demin plant, namely Strong Acid Cation (SAC) Exchanger. However, the difference is that the softener resin contains counter Na⁺ & nbsp; ions whose task is more specific to exchange with total hardness or total hardness (Ca²⁺ and Mg²⁺ cations) in the water.

Then what is hardness? Hardness is the mineral content or TDS in water in the form of calcium and magnesium ions in the form of carbonate, sulfate, chloride and nitrate salts. If the hardness content is high in water, the water is called hard water and if the hardness content is low, the water is called soft water. Hard water when mixed with soap will be difficult to foam, while soft water will produce a lot of foam.

There are two kinds of hardness:

• Temporary hardness: calcium and magnesium bicarbonate
• Permanent hardness: non-bicarbonate calcium and magnesium (sulfate, chloride and nitrate)
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To find out the type of hardness is quite easy, that is, if after heating the water and mixing soap it is still difficult to foam or the foam is small, then the water means it contains permanent hardness.

• Permanent hardness.

                    Total Hardness is the sum of carbonate + noncarbonate hardness. The sum of carbonate and noncarbonate hardness is determined from the water analysis as follows:

  • If M-Alkalinity >=Total Hardness then the hardness is carbonate (temporary)
  • If M-Alkalinity < Total Hardness then Carbonate hardness = M-Alkalinity; and Non-carbonate hardness = Total Hardness - M-Alkalinity

  Why do we need to remove or reduce hardness levels in water? Water with high hardness levels can cause scaling on the surface of metals, reducing their ability to transfer heat. For example, in the use of mild steel boilers, if the water contains high hardness, it will certainly result in a crusty boiler and reduced heat transfer so that the boiler performance is not optimal. That's why softeners are needed to convert hardness into Sodium ions.

  Then what are the operating conditions for softeners?

  Then what are the operating conditions for softener? Resin Softener operates under certain conditions, such as maximum inlet TDS 500 mg/l, typical linear flowrate 12 m/h, bed depth 750 mm and service flowrate 16 BV/h. The regenerant chemical used is 10% NaCl with a minimum contact time of 25 minutes.  Thus our short article this time, hopefully useful. Don't get tired to keep learning and see you in the next article.