Is it better to enter the resin tower alkali inlet from the middle or from the bottom? Why?

This unit enters from the lower part and exits from the upper part, which on the one hand can further loosen the resin and on the other hand make the alkali solution fully contact with the resin.

The flow direction of the material is determined by the different expansion properties of the resin under acidic and alkaline conditions. It is to ensure that the resin can change freely under acidic and alkaline conditions and to prevent the resin from being extruded and broken due to changes in volume. This is to ensure the long-term use and performance of the resin.

If you enter from the middle, the resin in the lower part cannot effectively play its role~ It is not good for resin regeneration.

During normal operation, the resin tower enters from the lower part and exits from the upper part.； During regeneration, enter from the top and exit from the bottom. ； Therefore, the nozzles of the resin tower should be at the top and bottom, not in the middle.

Speaking of the resin tower, I would like to ask everyone here how to fill it with brine after the resin tower is regenerated. We use a Canadian resin tower. Its design is that when the brine is filled, filtered brine enters directly from the top of the tower and then flows out from the bottom of the tower for recycling in the waste brine tank. In this way, the pure water in the tower is gradually replaced and then put into operation. However, in the past few days, I have seen that Asahi Kasei's resin tower does not do this at this step. Instead, the refined brine from the operating tower enters from the bottom of the regeneration tower and then comes out from the top of the tower to the recovery tank. I don’t know what’s so clever about Asahi Kasei’s design! In addition, when the new device was first started, the online tower was not running with no refined brine. So what should I do when filling the brine at this step? I hope you can give me some advice! !

1. The purpose of flushing salt water is to further loosen the resin layer. Because Asahi Kasei's process does not have the so-called air pressure bubbling process, it is necessary to backflush the salt water. 2. During the initial start-up, the resin tower regeneration starts from pure water backwashing and ends with flushing three. The function of pure water backwashing can be equivalent to that of salt water backwashing.

l What I said upstairs is more detailed. I would like to add that setting up the upper and lower parts is mainly based on: The volume of Na-type resin is 1.2~1.4 times that of H-type, and the resin will expand during alkali regeneration.

My understanding is: If ordinary brine is used, will the regenerated tower have already started ion exchange? I did some calculations and found that the same valve lines are used from the top in to the bottom out and from the bottom in and out. As mentioned in the 7th and 8th floor, it should be considered to further loosen the resin and further take away the broken resin. This post was last edited by limingshuguang on 2009-3-4 10:32 ]

In fact, there is no big difference in resin flushing with filtered brine and refined brine. They both drive away the pure water in the resin tower so that the resin tower is filled with brine of qualified concentration to avoid fluctuations in the concentration of the brine entering the tank. The purpose of Asahi Kasei to feed brine from the lower part is because the specific gravity of brine is greater than that of pure water. The brine is fed in from the lower part and comes out from the upper part. This way, the water in the tower can be driven away in the shortest time, so that the tower is filled with brine of qualified concentration and reduces the loss of refined brine. As for the new device that did not run the inline tower with no-refined brine when it was first started, what should we do when the brine is filled in this step? Asahi Kasei's process design is like this. There is a refined brine storage tank D508 behind the resin tower, which mainly serves as a brine buffer. When a new device is started, the brine is usually used to open the process first, and the brine is directly returned to the primary brine without entering the tank. The purpose is to take away impurities in the equipment pipelines after the resin tower. Therefore, it is enough to directly enter the filtered brine as soon as it is started, without the need for brine replacement. There's no need to worry. This post was last edited by limingshuguang on 2009-3-4 10:35 ]

It is absolutely correct that the lye enters from below. The purpose is to protect the resin and prevent it from breaking under pressure. The reason is: 1. The volume of the resin tower decreases during regeneration and pickling. 2. When alkali cleaning occurs, the resin volume expands. The expansion rate is approximately 40%. (It’s been a long time so I can’t remember it accurately.) 3. If alkali is added to the upper part, first the resin in the upper part comes into contact with the alkali and expands and compresses first. As the alkali liquid flows downward, the resin gradually expands from top to bottom. The further downward, the greater the pressure on the resin and the greater the breakage rate. On the contrary, the lower resin expands first, while the upper resin is puffy and is less pressurized. Therefore, in order to prevent the resin from breaking, it is usually chosen to feed alkali to the lower part and acid to the upper part. 4. Although the alkali in the middle part protects the upper resin, the lower resin is the same as mentioned in item 3. The most important thing is that the regeneration effect of the lower resin is not good, and there is a possibility of incomplete regeneration. Haha, this is just my one-sided understanding, please correct me if there are any mistakes. This post was last edited by david-2 on 2009-3-3 15:49 ]

Isn't there 170 behind the resin tower? No 508? What I mean is that if we directly enter the filtered brine from the top of the resin tower and then recover it from the bottom of the resin tower during the brine filling step during the first start-up, is it feasible? Or is it feasible to use filtered brine from the bottom and follow the process required by Asahi Kasei? In other words, is it possible for a tower that is not running online to directly use filtered brine without refined brine? If not, what are the disadvantages?

1. The resin tower in some process designs is connected to an intermediate tank at the back, and the position number is said to be D160. 2. The regeneration tower must be regenerated more than twice before the online tower is started for the first time. 3. Since there is no secondary brine, it is not feasible. Pure water backwashing is used instead of brine backwashing. 4. Just keep the online tower running normally when driving. This post was last edited by limingshuguang on 2009-3-4 10:38 ]

The alkali inlet of the resin tower is from the bottom. Advantages: 1. Fluffy resin 2. Easy to flush and break the resin 3. Small pressure difference, sufficient reaction

The resin tower in our process usually uses: 32% alkali is mixed with pure water to form about 4% dilute alkali solution. The alkali solution of the resin tower enters from the top of the tower to regenerate the resin. The hydrogen ions are replaced by sodium ions and the resin is converted into sodium form. The regeneration liquid comes out from the bottom of the resin tower and is then discharged to the wastewater storage tank.

In our company's resin tower, the alkali liquid enters from the top of the tower and is discharged from the bottom, which is conducive to fully regenerating the resin of the entire tower and flushing the broken resin.

It is easier and faster to regenerate the resin by entering from the bottom, because the alkali goes down layer by layer when entering from the top, and the contact area is larger when entering from the bottom, so entering from the bottom is conducive to regeneration. In addition, since there is no net in the upper part of the resin tower to intercept the resin, the broken resin can be flushed out of the resin tower as long as the appropriate water inlet backwash speed is maintained.

In fact, the principle of entering the alkali solution from the bottom is the same as that from the top. The function of the alkali is to convert the chelating resin from the hydrogen form to the sodium form. Different design units will have different design methods. As for the ability to loosen the resin and flush out the broken resin, I don’t think it is the main factor.