Petroleum Refining Design and Applications Handbook. A. Kayode Coker
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of 0.85–1.27 mm/s (2–3 in./min).
9 9. Gas velocity in gas/liquid separators, m/s (ft/s), with k = 0.11 (0.35) for systems with a mesh deentrainer and k = 0.0305 (0.1) without a mesh deentrainer.
10 10. Entrainment removal of 99% is attained with 102–305 mm (4–12 in.) mesh pad thickness; 152.5 mm (6 in.) thickness is popular.
11 11. For vertical pads, the value of the coefficient in step 9 is reduced by a factor of 2/3.
12 12. Good performance can be expected at velocities of 30–100% of those calculated with the given k; 75% is popular.
13 13. Disengaging spaces of 152–457 mm (6–18 in.) ahead of the pad and 305 mm (12 in.) above the pad are suitable.
14 14. Cyclone separators can be designed for 95% collection of 5-µm particles, but usually only droplets greater than 50 µm need be removed.
VESSEL (PRESSURE)
1 1. Design temperature between −30 and 345°C is 25°C (−20° F and 650°F if 50°F) above maximum operating temperature; higher safety margins are used outside the given temperature range.
2 2. The design pressure is 10% or 0.69–1.7 bar (10–25 psi) over the maximum operating pressure, which-ever is greater. The maximum operating pressure, in turn, is taken as 1.7 bar (25 psi) above the normal operation.
3 3. Design pressures of vessels operating at 0–0.69 barg (0–10 psig) and 95–540°C (200–1000°F) are 2.76 barg (40 psig).
4 4. For vacuum operation, design pressures are 1 barg (15 psig) and full vacuum.
5 5. Minimum wall thickness for rigidity: 6.4 mm (0.25 in.) for 1.07 m (42 in.) diameter and under, 8.1 mm (0.32 in.) for 1.07–1.52 m (42–60 in.) diameter, and 9.7 mm (0.38 in.) for over 1.52 m (60 in.) diameter.
6 6. Corrosion allowance 8.9 mm (0.35 in.) for known corrosive conditions, 3.8 mm (0.15 in.) for noncorrosive streams, and 1.5 mm (0.06 in.) for steam drums and air receivers.
7 7. Allowable working stresses are one-fourth the ultimate strength of the material.
8 8. Maximum allowable stress depends sharply on temperatureTemperature (°F)−20–6507508501000(°C)−30–345400455540Low-alloy steel, SA 203 (psi)18,75915,65095502500(bar)12901,070686273Type 302 stainless (spi)18,75018,75015,9506250(bar)129012901100431
VESSELS (STORAGE TANKS)
1 1. For less than 3.8 m3 (1000 gal.), use vertical tanks on legs.
2 2. For 3.8–38 m3 (1000–10,000 gal.), use horizontal tanks on concrete supports.
3 3. Beyond 38 m3 (10,000 gal.) use vertical tanks on concrete foundations.
4 4. Liquids subject to breathing losses may be stored in tanks with floating or expansion roofs for conservation.
5 5. Freeboard is 15% below 1.9 m3 (500 gal.) and 10% above 1.9 m3 (500 gal.) capacity.
6 6. A 30-day capacity often is specified for raw materials and products but depends on connecting transportation equipment schedules.
7 7. Capacities of storage tanks are at least 1.5 times the size of connecting transportation equipment; for instance, 28.4-m3 (7500 gal.) tanker trucks, 130-m3 (34,500 gal.) rail cars, and virtually unlimited barge and tanker capacities.
Source: The above mentioned rules of thumb have been adapted from Walas, S.M., Chemical Process Equipment: Selection and Design, copyright 1988 with permission from Elsevier, all rights reserved.
Physical Properties Heuristics.
| Units | Liquids | Liquids | Gases | Gases | Gases | |
|---|---|---|---|---|---|---|
| Water | Organic material | Steam | Air | Organic material | ||
| Heat capacity | kJ/kg °C | 4.2 | 1.0–2.5 | 2.0 | 1.0 | 2.0–4.0 |
| Density | kg/m3 | 1000 | 700–1500 | 1.29 at STP | ||
| Latent heat | kJ/kg | 1200–2100 | 200–1000 | |||
| Thermal conductivity | W/m °C | 0.55–0.70 | 0.10–0.20 | 0.025–0.07 | 0.025–0.05 | 0.02–0.06 |
| Viscosity | kg/ms | 0°C 1.8 × 10−3 | Wide Range | 10–30 × 10−6 | 20–50 × 10−6 | 10–30 × 10−6 |
| 50°C 5.7 × 10−4 | ||||||
| 100°C 2.8 × 10−4 | ||||||
| 200°C 1.4 × 10−4 | ||||||
| Prandtl no. | 1–15 | 10–1000 | 1.0 | 0.7 | 0.7–0.8 |
Source: Turton, R. et al., Analysis, Synthesis, and Design of Chemical Process, Prentice Hall International Series, 2001.
Typical Physical Property Variations with Temperature and Pressure.
| Liquids | Liquids | Gases | Gases | |
|---|---|---|---|---|
| Property | Temperature | Pressure | Temperature | Pressure |
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