Читать книгу Petroleum Refining Design and Applications Handbook - A. Kayode Coker - Страница 22

1 1. Structured and random packings are suitable for packed towers less than 0.9 m (3 ft) when low pressure drop is required.

2 2. Replacing trays with packing allows greater throughput and separation in existing tower shells.

3 3. For gas rates of 14.2 m3/min (500 ft3/min), use 25.4-mm (1-in.) packing; for 56.6m3/min (2000 ft3/min) or more use 50-mm (2-in.) packing.

4 4. Ratio of tower diameter/packing diameter should be > 15/1.

5 5. Because of deformability, plastic packing is limited to 3–4 m (10–15 ft) and metal packing to 6.0–7.6 m (20–25 ft) unsupported depth.

6 6. Liquid distributors are required every 5–10 tower diameters with pall rings and at least every 6.5 m (20 ft) for other types of dumped packing.

7 7. Number of liquid distributions should be >32–55/m2 (3–5/ft2) in towers greater than 0.9 m (3 ft) diameter and more numerous in smaller columns.

8 8. Packed towers should operate near 70% of the flooding rate (evaluated from Sherwood and Lobo correlation).

9 9. Height Equivalent to a Theoretical Stage (HETS) for vapor–liquid contacting is 0.4–0.56 m (1.3–1.8 ft) for 25-mm (1-in.) pall rings and 0.76–0.9 m (2.5–3.0 ft) for 50-mm (2-in.) pall rings.

10 10.Generalized pressure dropsDesign pressure drops (cm of H2O/m of packing)Design pressure drops (in. of H2O/ft of packing)Absorbers and Regenerators (non-foaming systems)2.1–3.30.25–0.40Absorbers and Regenerators0.8–2.10.10–0.25Atmospheric/Pressure Stills and Fractionators3.3–6.70.40–0.80Vacuum Stills and Fractionators0.8–3.30.10–0.40Maximum value8.331.0