Usage Of Mixed Bed Anion And Cation Exchange Resin

1. Pre treatment of new resin:

Due to various reasons such as transportation and storage, it is easy for the new resin to dehydrate. It can be detected with the naked eye and feel. In such a situation, in order to avoid the resin from coming into contact with water and other regeneration liquids and causing unnecessary waste, it is necessary to soak this type of resin in 8% salt water for about 16 hours (stirring frequently during soaking), so that the resin can fully expand and be rinsed with clean water until there is no salt smell before use. If there is no such phenomenon, the resin does not need to undergo pre-treatment.

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. In non ecological conditions (i.e. when cation resin is sodium type and 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. The filling ratio of Yin Yang resin is 2:1 (or 1.5:1). Cation exchange resin at the bottom and anion exchange resin at the top.

3. Resin flushing:

After the resin is loaded into the exchanger, backwash the resin layer with clean water until the effluent is clear, odorless, and free of fine resin particles. Using a 4-5% HCl solution that is approximately twice the volume of the resin, pass through the resin layer at a flow rate of 2m/h. After being fully immersed, soak for 4-8 hours, drain the acid, and rinse with clean water until the effluent is neutral, with a flushing flow rate of 10-20 m/h. Using a 2-5% NaOH solution that is approximately twice the volume of the resin, introduce and soak it using the method of adding HCl solution as described above. Drain the alkaline solution and rinse with clean water until the effluent is neutral. The flushing flow rate is the same as above. If acid and alkali solutions can be repeated 2-3 times, the effect will be better.

4. Yin Yang resin mixture:

After flushing, open the lower inlet and upper discharge valves, start the middle water pump (backwashing causes the resin layer to loosen), and when the accumulated water in the column is discharged to 100-150mm above the resin layer, close the middle water pump and inlet valve; 2. Open the small amount of exhaust valve, open and control the intake volume of the intake valve (intake pressure is 0.1-0.15Mpa), observe the rhythmic boiling and mixing of resin in the upper and lower sight glasses, so that the color of the upper and lower resins is consistent. The intake time is generally 10-15 minutes; 3. After mixing, close the intake valve and exhaust valve, then quickly open the upper inlet valve, middle water pump, and lower discharge valve (to allow the resin to settle quickly and prevent the resin from re layering during the settling process). At the same time, it is necessary to prevent the resin from coming out of the water surface, otherwise bubbles will be generated between the resins, which will affect the effluent quality of the mixed bed (if the mixing effect is poor, the mixing operation can be repeated).