Factors affecting the exchange capacity of the fully automatic sodium ion exchanger
1. flow rate (gpm / ft, m / h)
Generally, the greater the flow rate, the larger the working layer required for ion exchange, and the effective resin utilization will decrease, but the water production capacity of the fully automatic sodium ion exchanger will increase. Conversely, the smaller the flow rate, the fewer working layers required, and the resin utilization rate increases, but the water production capacity of the equipment decreases. If the flow rate is too small, the raw water will only exchange ions with the surface of the resin, and the water cannot enter the resin. The resin surface usually provides only 20% of the exchange capacity. Resin inside can provide 80% exchange capacity. Reasonable exchange flow rate is very important to improve the water production capacity and exchange capacity of the equipment. It is generally recommended that the operation flow rate be controlled at (20-30m / h in China, 4-10pm / ft2 in the United States). The small automatic sodium ion exchanger device can be appropriately increased .
2. Contact time between water and resin: (gpm / ft3)
The longer the contact time between water and resin, the more adequate the exchange, but the relative water production capacity of the unit resin decreases. The shorter the contact time, the more adequate the exchange, the exchange capacity of the unit resin decreases, and the water production capacity of the unit resin increases. Therefore, a reasonable connection time is very important for the economic operation of the softener. Generally recommended 1.0-5.0gpm / ft3 resin or 8-4bv / h. (The flow rate per hour is eight to forty times the resin load)
3. The height of the resin layer
The lower the resin layer of the automatic sodium ion exchanger tank, the greater the influence of the flow rate on its exchange capacity. When the height of the resin layer reaches 30 feet (762mm), the influence of the flow rate caused by the height of the resin layer on its exchange capacity can be Reduced to a relatively low level. Therefore it is generally recommended that the height of the resin layer is greater than 30 feet (762mm)
4. Inlet water salinity
The level of salt content in the influent directly affects the quality of the effluent, and the total content of K and Na in the salt content of the influent has a great influence on the quality of the effluent.
Example: When the salt content of the raw water is 500PPM, where Na + K is zero, and the hardness is 10mol / m3, if we regenerate 151b / ft3 (240g / L), the effluent quality can reach nearly 0.00.
When the salt content of the raw water is 500PPM and Na + K is 250PPM, the hardness is 5mol / L close to 0.04mmol / L (more than the national low-pressure steam boiler inlet water requirement). If the effluent reaches 0.03mmol / L or less, it must be used (181b / ft3, 290g / L)
The increase in water temperature can simultaneously accelerate internal diffusion and improve the exchange capacity. Whether it is running or regeneration, it is beneficial to fully automatic sodium ion exchangers to properly increase the water temperature.
6. Regenerant quality (NaCl)
The higher the regeneration agent storage, the higher the regeneration degree of the resin, and the less the ion leakage of the effluent. Therefore, improving the purity of the regeneration agent and softening the water-soluble salt can improve the regeneration degree.
7. Regenerative fluid flow
Generally, the smaller the regeneration liquid flow rate, the better the regeneration effect. But too low regeneration fluid flow will make the regeneration time too long, and it is easy to make the regeneration agent bypass the resin surface for regeneration. Therefore, the flow rate of the regeneration liquid is generally required to be 0.25-0.9gpm / ft3 (or the flow rate of the flushing is 4-6m / h, and the reverse flow regeneration is 2-3m / h)
8. Regenerated liquid concentration
According to the principle of ion balance, increasing the concentration of the regeneration liquid can improve the exchange capacity of the resin. However, under a certain amount of regeneration agent, the concentration of the regeneration liquid is too high, which will shorten the contact time of the regeneration liquid and the resin, thereby reducing the regeneration effect. General It is appropriate to control the concentration of the salt solution to about 10%.
9. Reagent dosage
The exchange of resin in theory of regeneration is carried out in an equivalent amount, that is, 1mol of regenerant can restore a 1mol of exchange capacity, (that is, using 58.43 NaCl). But in fact, the consumption of regenerant is much larger than the theoretical value. It proves that the more the amount of regenerant used, the greater the resin work exchange capacity obtained. The better the effluent quality. But as the amount of regenerant continues to increase, the job exchange capacity will increase less and less. Economics will continue to decline. Therefore, the regeneration of salt consumption should be based on different raw water quality, and then to ensure a certain exchange capacity and water quality conditions, as far as possible to choose a more economical and reasonable salt consumption. In the automatic sodium ion exchanger of the general low-pressure boiler in the United States, 240 g / l salt is used to regenerate 1 liter of resin.
Different resins provide different exchange capabilities. Generally, the automatic sodium ion exchanger used in boilers requires that the resin used should have a crosslinking degree of not less than 7.