Newly loaded resin top level is 7cm less after the 1st time regen 1

[Nicksun]

Dear All,
i had made a MB internal repair for one client, and then loaded with new MB resin(R&H 1400H/4000OH). and i loaded till resin level reached the middle of middle sight glass.

but after the first regeneration, the top level is 7 cm lower??!!

the first reaction is resin is leaking from HCL distrubtors or/and middle drain collectors, but we check the two points, there are no resin beads in the water.

so what could be the reason??

and more: after loading, we rinsing and backwashing, so the top level should be flat at that time.

thanks for your kind input.

regards, nick

 

[bimr]

Resin shrinks and swells while in service. That is a big reason that the resin breaks in pieces while in use. Look up the specific resin that you have. Here is some typical information:

Design Guidelines for Operating DOWEX™ Resins

Swelling:
Strong Acid Cation Na+ > H+ 5-8%
Weak Acid Cation H+ > Ca+ 15-20%
Strong Base Anion Cl- > OH- 15-25%
Weak Base Anion FB > HCl 15-25%

 

[Nicksun]

Hi,bimr,

Based on your advice - swelling/shrinking concept, i would like to guess: when resin is new, it is totally swellen for SAC/SBA resin. When the new resin is exhausted, it got shrinken for SAC/SBA resin which is about 8% and 20% less for SAC and SBA respectively. But when it is regenerated to some extent - say 90% its full capacity,
so, say 1m SAC in H form and 1m SBA in OH form when new,
after exhaust, 920mm+800mm = 1.72m, which is 2-1.72=380mm less.
and after 90% regeneration, it should be 380 x 10%=38mm less than original height.

of course when it is 80% regen level, it should be 380x20%= 76mm less.

Is that right?

That is the

 

[bimr]

That is probably correct. Note that the ion exchange bed will pack down somewhat as the fluid moves through it.

 

[Nicksun]

Thanks for bimr's insights.

Next Monday, another regeneration will be made. at that time, if the top level keeps the same with last one, we can tell it is due to regeneration level problem.
if the level goes down again, which i don't want to see, the resin is lost due to some reason.

Ok, i will keep you updated.

regards, Nick.

 

[Nicksun]

Yes, it is right.

Due to different regeneration level, the top level is 7cm than the original level.

Nick