Cation regeneration- H2SO4 or HCl 3

[gkandy]

Some cation beds are regenerated with sulfuric acid and some with HCl. Obviously it depends upon the type of resin structure and exchange . I would like to know

1 ) What is the criteria which decides whether one uses a H2SO4 or HCl regenerated bed ?

2 ) Which is the better option from resin life , regeneration , safety , throughput for the lifetime of the resin etc.

Thanks

Kandy

 

[GarySCWSVI]

First, commonly used cation resin can be regenerated with either. The resin structure or exchange has nothing to do with which of those regenerants to use since the H ion is the regenerating ion.

Second, the criteria is usually cost related. H2SO4 is lower in cost. It also comes in a higher concentration than HCl. H2SO4 can be stored in steel tanks. HCl, in the USA, is used most often. H2SO4 is more commonly used, for whatever reason, outside the USA. HCl requires less equipment modification. That is because H2SO4 is fed by means of a two,three or four stage process. This because H2SO4 can cause mineral precipitation if fed the required concentration at one time. The equipment needs to be set up to do that. HCl regeneration is a one stage process. H2SO4 also is less efficient than HCl

Third, some select H2SO4 because the user is already using H2SO4 somewhere else in their facility. Some select HCl for the same reason.

Fourth, properly applied and operated, resin life will be the same using either regenerant.

 

[gkandy]

Gary thanks for your clarification. Can a bed which is being regenerated with H2SO4 be switched over to HCl or vice versa ?

I understand the storage tank, the pipeline ,ejectors for feeding the acid will have to be modified. I would like to know whether there will be any problem as far as the resin is concerned.

One of my friends informed me that their resin supplier wants a NaCl wash/regeneration for their anion bed. What is the idea / theory behind this.

Thanks in advance for your time.

Kandy

 

[GarySCWSVI]

Yes, you can make that switch. No problem for the resin.

NaCl can be used to regenerate an anion resin for such applications Dealkalization, Nitrate removal or Sulfate removal. In this case the resin operates in the Cl form to exchange Alkalinity, Nitrates or Sulfates for Cl.

If the anion resin is being used in a Demineralizer NaCl is used on a one time basis to defoul an organically fouled anion resin. In this case the NaCl causes anion resin beads, that are normally operated in the OH form and have become organically fouled, to shrink and, much like squeezing a sponge, forces the accumulated organics out. The process is typically called doing a "warm brine squeeze".

 

[wiggs]

We have used HCl to regenerate when H2SO4 caused CaSO4 fouling.