Summary for mixed bed polisher performance Discussion
Mixed bed polisher performance can drop before the design throughput is reached if the upstream units are not producing water within spec. In this thread, Amanda Loo asks why regeneration is needed early, suspecting resin exhaustion or sodium leakage. Vishal Kuarsingh explains that the design throughput varies by manufacturer, but the more likely issue is that the anion effluent is out of spec and cations are slipping through early. He recommends checking silica leaving the anion unit, monitoring anion conductivity, and verifying that regeneration steps for all units use the correct acid and caustic concentrations. If those checks do not solve the problem, he advises opening the vessel to inspect for broken or missing internal parts. The thread also includes a later question from Rajnikant Gohi asking about the effect of resin loss from a mixed bed and what checklist should be used to inspect the resin.
Q. I’m a chemical engineering student. Currently I’m doing a assignment related with the possible cause that affect the performance of mixed bed polisher. The problem definition is as below: For the past week, the MBP are regenerated before achieving the desire throughput as indicated by totalizer. The regeneration has to start when the conductivity has reached the set value although the throughput is less than design volume. It is not only affects the cycle time but also the consumption of chemical. Thus, cost incurred in term of increasing chemical injection. possible cause: exhaustion of resin, sodium leakage(conductivity increase) Can you further explain on the above cause and other possible causes.What is the life span of mixed bed polisher?
Thank you,
Amanda Loo
– Malaysia
A. The design throughputs on the polisher varies from manufacturer to manufacturer. However it seems that the anion effluent is not within spec and the cations are also slipping Na early. Do a lab check for silica exiting the anions and make sure it is within spec. You will also have to watch the conductivity on the anions as high conductivity indicates that the cations are slipping which will eventually reach it’s way down to the polisher. More importantly the regenerations of all these units can determine if they reach design throughputs
(provided that nothing is mechanically wrong with the interior of the vessel). Lab checks should be done at each stage of the regeneration to make sure that the acid and caustic are within the desired concentrations. If all this fails the vessel should be opened and inspected for broken and missing parts. There are more factors involved but you will have to email me if you want.
Vishal Kuarsingh
– Trinidad and Tobago
Q. IN MIXED BED, THE RESIN IS OUT OF SYSTEM. WHAT IS ITS EFFECT ON MAKING OF WATER OR ph/CONDUCTIVITY. WHAT IS THE CHECK LIST FOR CHECKING MIXED BED RESIN?
RAJNIKANT GOHI
– SURAT, GUJARAT, INDIA
June 9, 2013