IX Resin Degradation

[waterweasel]

working with a customer who is experiencing high conductivity in WFI stills following his pretreatment train thinking it is possibly due to ammonia from not reaching breakpoint with chlorination. Train is city water influent, chlorination using industrial bleach to 5 ppm free chlorine, contact time in a tank, pass through multimedia filters, through softeners, then dechlorination with sodium bisulfite to process.

I am wondering if the high free chlorine levels going through the IX beds in breaking down the resin and releasing organics which are elevating the conductivity in his WFI water. I cannot believe that the nitrogen compounds would be that high in city water that he is not achieving breakpoint with 5 ppm free measured with Hach CL-17 (recently calibrated/serviced)

Any thoughts??

 

[quark]

I don't know about nitrogen compounds but 5 ppm chlorine is dangerous to the IX resins. We do use some cation resins that can withstand free chlorine upto 2 ppm. What is the input water quality to WFI still?

Generally, you should get a conductivity of less than 1.3microsiemens/cm with input water quality of not more than 5microsiemens/cm. If the water quality is good, check for the flooding of the first column, leakage in condenser and purified water flowrate vis-a-vis steam flowrate.

 

[waterweasel]

Quark,

The influent to the still is the effluent from the softeners plus some bisulfite to dechlorinate. Conductivity is probably on order of 200 mmhos

 

[GarySCWSVI]

The chlorine, regardless of the resin's ability to withstand it, will always cause the softening resin to release organics. The resin is made up entirely of organic chemicals. The best solution is to treat the chlorine prior to the water softener either by removal or by bisulfite feed.

Gary Schreiber, CWS VI
The Purolite Co.