We are operating an old plate-and-frame filter press to filter polymer from the water/ascetic acid supernatent produced in the process. Local "artist" operators and SOPs based upon legend tend to provide inconsistent and non-scientific-based proposals for lifter press optimization. Could you direct me to a basic plate-and-frame filtration operation scheme designed to use the filter properly and most efficiently? Questions are very basic and include:
1. Feed from the top? Feed from the bottom?
2. Wash from the top? Wash from the bottom?
3. Blow down from top? Up from Bottom?
4. Cycle wash directions? Co-current or counter current washes?
5. Dilute feed at first? For how long?
6. Benefits of altering solids content in feed while loading? Variable feed rates?
Have an insight or suggestion?
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Re: Finding a Filtration Scheme that Filters Properly and Efficiently
21 October 2008 at 1:29pm1) One usually only feeds from the bottom if the slurry tends to settle. Otherwise, we feed from the top corner. We rarely use center feeding.
2) One should wash from the top left cross-wise and out the bottom right.
3) Always blow down from the top to the bottom so liquid drains out.
4) Countercurrent, because one wants the wash to go through the cake (i.e., from the top left to the bottom right or from the top right to the bottom left depending on how the press is ported).
5) We never dilute the feed since thicker slurries are generally easier to filter.
6) Altering feed solids isn't a good idea based on (5) above. Variable feed rates are generally accomplished anyway as the cake builds up. Hence, one starts at a fairly high flowrate to fill the press, which then drops off fairly rapidly as the cake builds up. This is why pump selection is critical.
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