aspearin1
Chemical
- Nov 5, 2002
- 391
Greetings Gentlepersons,
I'm trying to develope a cation exchange system using natural zeolites on our process fluid. To date, I have performed laboratory tests on packed columns. I have tested 2 different conditions, each condition contains 450 mL ~40 mesh zeolite, operating at 10 bed volumes per hour, with ~60 ppm of the contaminant flowing in at a constant rate. The difference between the two is direction of flow. Condition 1 was pumped from the bottom of the column. This gave some nice results, decent breakthrough curves, all except that I could see air entrapment below fibrous plug at the bottom of the packed bed. I assumed this might cause channeling. I reversed the flow for Condition 2, and got results that are strange. The breakthrough curves follow the basic trend of increasing concentration, only they oscillate. The data basically says that sometimes it takes out more, sometimes less, and almost looks much like it's not at steady state. The oscillations don't match with sampling times, nor the pulses of the peristaltic pump I used.
Does anyone have similar experiences modeling breakthrough? Could this be the difference between fixed bed and fluidized bed exchange? Could random channeling cause regular oscillations? For ion exchange, which method is prefered, fluidized or fixed bed? I've seen contradicting literature.
I know it's wordy, but I appreciate your attention. thanks.
I'm trying to develope a cation exchange system using natural zeolites on our process fluid. To date, I have performed laboratory tests on packed columns. I have tested 2 different conditions, each condition contains 450 mL ~40 mesh zeolite, operating at 10 bed volumes per hour, with ~60 ppm of the contaminant flowing in at a constant rate. The difference between the two is direction of flow. Condition 1 was pumped from the bottom of the column. This gave some nice results, decent breakthrough curves, all except that I could see air entrapment below fibrous plug at the bottom of the packed bed. I assumed this might cause channeling. I reversed the flow for Condition 2, and got results that are strange. The breakthrough curves follow the basic trend of increasing concentration, only they oscillate. The data basically says that sometimes it takes out more, sometimes less, and almost looks much like it's not at steady state. The oscillations don't match with sampling times, nor the pulses of the peristaltic pump I used.
Does anyone have similar experiences modeling breakthrough? Could this be the difference between fixed bed and fluidized bed exchange? Could random channeling cause regular oscillations? For ion exchange, which method is prefered, fluidized or fixed bed? I've seen contradicting literature.
I know it's wordy, but I appreciate your attention. thanks.
