Issues with alkali washing during resin column regeneration

As long as it can ensure that the resin column reaches its designed capacity, any such method will do

We use Asahi Kasei’s product; for alkaline cleaning, the flow is from top to bottom

Typically, the alkali washing of our resin columns involves using 32% alkali mixed with pure water to create a dilute alkali solution of about 4%; this solution is introduced at the top of the column to regenerate the resin, with hydrogen ions being replaced by sodium ions, thus converting the resin to its sodium form. The regenerated solution then exits at the bottom of the column and is discharged.

We are also from Asahi Kasei; the flow is from top to bottom. Only in the reverse washing process is the flow from bottom to top. In fact, alkali washing simply converts the hydrogen form into the sodium form, so as long as the conversion is complete through alkali washing, it doesn’t really matter where the flow comes from. This is just my personal understanding; I hope experts can give me some guidance

There is also the possibility that the volume of the resin changes during the transformation process; to reduce the mutual compression of the resins, the flow direction is taken into consideration.

The resin expands in the sodium form (0.61 to 1?) ), if alkali is introduced from the upper part, first the resin in that area comes into contact with the alkali, causing it to expand and become compressed. As the alkaline solution flows downward, the resin expands gradually from top to bottom; the further down it goes, the greater the pressure on the resin, and thus the higher the rate of fragmentation. Therefore, in order to prevent the resin from breaking, it is common to introduce the alkali from the bottom. Last edited by yzhms on 2009-4-3 14:16.]

Advantages of the bottom-in/top-out process: 1. Facilitates complete reaction of the resin; 2. Helps preserve the integrity of the resin; 3. Helps save caustic soda; 4. Allows for proper observation of the resin regeneration process; 5. Facilitates the removal of broken resin, thereby reducing pressure differences

The Asahi Kasei process uses a top-in bottom-out configuration, while the bottom-in top-out approach has many advantages. Is this a design mistake by Asahi Kasei, or is it a requirement of the process? Or does the top-in bottom-out configuration also have its own merits?

We are Woody Craft, using a bottom-in, top-out method. In principle, alkaline washing causes the resin to expand slightly, which reduces pressure and lowers the rate of resin damage. For pickling, the flow is from top to bottom.

By the way, the effect of going down and up should be no different. It’s a bit more difficult to arrange the downward pipes. High requirements are placed on the resin collectors.

Under acidic conditions, the volume contracts; therefore, the concentration of the acid used for regeneration must not exceed 10%, otherwise the volume contraction will cause compression and an increase in the fragmentation rate.

It is better to adopt a process with material entering from below and exiting from above, as this is beneficial for the expansion of the resin

There is no essential difference; the two methods are merely different *habits in terms of design. Wood and Asahi Kasei are suppliers of saltwater purification units that belong to two different **categories, just as everyone’s living *habits vary. Additionally, the function of alkali washing the resin is merely to convert it from the hydrogen form to the sodium form. 4% caustic soda is more than sufficient to meet the requirements for this conversion, based on theoretical calculations. As for introducing the alkali from the bottom, it is claimed that this can help loosen the resin and reduce its fragmentation rate; however, there is no theoretical basis to support this claim. Given the operating cycle of the resin, the total time spent in operation plus regeneration is currently at least 30 hours (24 hours of operation per column followed by 6 hours of regeneration), while the time required for alkali washing is much shorter, at only 1.5 hours (and even less if the operation time is 48 hours). Such a short time has little impact on loosening the resin or reducing its fragmentation, so this is merely a matter of design convention and does not carry any special significance. This post was last edited by yzhms on 2009-4-3 14:17]

Backwashing has been taken into account during washing, and backwashing is also considered for the subsequent brine replacement. Acid-base backwashing is also possible. If backwashing is used for acids and bases, the acidity or alkalinity in the resin catcher must be taken into consideration, after all, it is manual labor that is used to remove the resin.

I personally still agree with what the person on floor 14 said; it makes a lot of sense! :lol

We work in the field of chlorine engineering; fluid flows in from below and out from above. During alkali regeneration, the resin expands and becomes fragile, which helps to loosen the resin as well as ensure a more uniform alkali reaction

We at Asahi Kasei use a top-to-bottom processing method, but I also agree with the view from the 14th floor; the analysis is good.

We use Asahi Kasei’s product; for alkaline cleaning, the flow is from top to bottom