Читать книгу Petroleum Refining Design and Applications Handbook - A. Kayode Coker - Страница 27

1 1. Process are classified by their rate of cake buildup in a laboratory vacuum leaf filter: rapid, 0.1–10.0 cm/s; medium, 0.1–10.0 cm/min; and slow, 0.1–10.0 cm/h.

2 2. Continuous filtration should not be attempted if 1/8 in. cake thickness cannot be formed in less than 5 min.

3 3. Rapid filtering is accomplished with belts, top feed drums, or pusher centrifuges.

4 4. Medium rate filtering is accomplished with vacuum drums or disks or peeler centrifuges.

5 5. Slow-filtering slurries are handled in pressure filters or sedimenting centrifuges.

6 6. Clarification with negligible cake buildup is accomplished with cartridges, precoat drums, or sand filters.

7 7. Laboratory tests are advisable when the filtering surface is expected to be more than a few square meters, when cake washing is critical, when cake drying may be a problem, and when precoating may be needed.

8 8. For finely ground ores and minerals, rotary drum filtration rates may be 15,000 lb/day-ft2 at 20 rev/h and 18–25 in. Hg vacuum.

9 9. Coarse solids and crystals may be filtered at rates of 6000 lb/day-ft2 at 20 rev/h and 2–6 in. Hg vacuum.