[Hongjie Water Service] Resin softening and regeneration process

When the resin exchange in the softener saturates, regeneration treatment is required to restore the resin's exchange capacity. The regeneration process of resin can be divided into forward flow regeneration and reverse flow regeneration according to the flow direction of the regenerated salt solution. When the flow direction of the regenerated salt solution is the same as that of the operating raw water, it is called downstream regeneration, and when the two flow directions are opposite, it is called countercurrent regeneration. The regeneration process of the lubrication softener involves main steps such as backwashing, regeneration, displacement, and washing.

(1) Backwashing process

After the resin fails, the first step is to use backwash water to backwash the resin from bottom to top. The backwashing process can remove suspended solids and impurities such as broken resin trapped in the resin layer, and can break the resin bond even if the resin is loose, so that the regenerated salt solution can be evenly distributed in the resin layer. It is best to use softened clean water for backwashing, and the effect of backwashing with system raw water is poor. The backwash flow rate is about 10m/h, and the backwash time is 10-15 minutes.

(2) Regeneration process

After the backwashing process is completed, it should enter the regeneration process. The regeneration process of resin follows the principle of equal substance exchange, and 1mol NaCl can restore the exchange capacity of the exchange resin to 1mol. Domestic 001 × The wet resin of 7 is calculated based on a total exchange capacity of 2.0mol/L and a wet apparent density of 0.85kg/L. The theoretical requirement for regeneration of strong acidic cation exchange resin is 58.5% per kilogram × 2/0.85=137.75g NaCl, and the actual salt consumption to achieve better regeneration effect is about 2.0-3.5 times the theoretical salt consumption, which is 275.5-482g of salt per kilogram of resin. If the salt consumption of downstream regeneration is high, its high value should be taken, while if the salt consumption of countercurrent regeneration is low, its low value should be taken. The relationship between the NaCI consumption per mole of resin, i.e. the specific salt consumption and the degree of resin regeneration, is shown in Figure 2.8. During the regeneration process, the concentration of regenerated salt solution should be maintained at 5% -10%, and the flow rate of regenerated solution should be controlled at 6-8m/h. The regeneration effect is highly sensitive to the hardness of the regeneration solution, and softened clean water should be used as the regeneration solution as much as possible, especially avoiding the use of high hardness raw water.

(3) Water body replacement

Water replacement is a continuation step of the regeneration process. After the regeneration process is completed and salt injection is stopped, there is still salt liquid that has not been involved in regeneration in the upper part of the exchanger and the resin. In order to fully utilize this part of the salt liquid and discharge the regenerated salt liquid and regenerated products from the softener, clean water should continue to be injected into the resin bed in the direction and flow rate of the regenerated liquid, so that the regenerated liquid in the exchanger is discharged from the softener while further regenerating the resin. The general replacement water volume is 0.5-1 times the resin volume.

(4) Salt tank water replenishment

After the regeneration of saline water is completed, the required water for regeneration should be replenished into the salt tank. Under the working condition of 25 ℃, when 360g of salt is dissolved in 1L of water, it reaches saturation (concentration of 26.4%). To saturate the salt solution in the salt tank, it should be ensured that the dissolution time is greater than 6 hours and there is sufficient solid salt in the salt tank.

(5) Washing process

After the replacement of the water body or before the standby exchanger is put into operation, in order to discharge the regenerated salt solution and regenerated products from the softener, it is necessary to use cleaning water to perform forward cleaning in the direction of the original water flow until the effluent hardness is qualified before the resin washing is completed. The general washing water volume is 3-6 times that of resin.

More information can be found on the official website of Shenzhen Hongjie Water Technology Co., Ltd. www.czhengwei.net. If you need it, you can call the company's hotline for free at 180 3800 0078, and we will be happy to serve you.