Application of anion and cation exchange resin in mixed bed
1. Pretreatment of the new resin:Due to the transportation and storage and other reasons, it is easy to dehydrate the new resin. It can be found by the naked eye and hand. In this case, in order to prevent the resin from bursting and breaking in contact with water and other regeneration liquid, and cause unnecessary waste, this kind of resin must be soaked in 8% salt water for about 16 hours (often stirred during soaking), so that the resin can be fully expanded and rinsed with clean water until it has no salt taste. Without the above phenomenon, the resin does not need to be pretreated.
2. Resin filling:
The resin filling height of domestic mixed bed equipment is 5 (6) 00mm for cation resin and 10 (2) 00mm for anion resin. When the cation resin is sodium type and the anion resin is chlorine type, the filling height of cation resin should not be higher than the middle outlet, but should not be lower than 5cm for the middle outlet. The loading ratio of cation and anion resin is 2:1 (or 1.5:1). The cation exchange resin is lower and the anion exchange resin is higher.
3. Resin washing:
After the resin is loaded into the exchanger, the resin layer is backwashed with clean water until the effluent is clear, odorless and free of fine resin. A 4-5% HCl solution about twice the volume of resin was used to pass through the resin layer at a flow rate of 2m / h. After all of them are filled in, soak for 4-8 hours, drain the acid, and rinse with clean water until the effluent is neutral, with the flushing flow rate of 10-20m / h. Use 2-5% NaOH solution which is about twice the volume of the resin to inject and soak it as HCl solution. Drain the lye and flush with clean water until the effluent is neutral. The flushing flow rate is the same as above. If acid and alkali solution can be repeated 2-3 times, the effect is better.
4. Mixing of cation and anion resins:
After flushing, open the lower inlet and upper discharge valves, start the middle water pump (backwashing makes the resin layer loose), and close the middle water pump and inlet valve when the water in the column is drained to 100-150 mm above the resin layer; 2. Open a small amount of vent valve, open and control the intake volume of the intake valve (the intake pressure is 0.1-0.15mpa), observe the rhythmic up and down boiling mixing of the resin in the upper and lower endoscope, and make the color of the upper and lower resins consistent. The air intake time is generally 10-15 minutes; 3. After mixing, close the air intake valve and vent valve, and then quickly open the upper inlet valve, middle water pump and lower discharge valve (to make the resin settle rapidly and prevent resin from re stratification in the process of settling). At the same time, it is also necessary to prevent the resin from coming out of the water, otherwise there will be bubbles between the resins, which will affect the effluent quality of the mixed bed (if the mixing effect is not good, the mixing operation can be repeated).
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