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VESSELS (STORAGE TANKS)

Оглавление

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
Density Negligible ρg = MW P/ZRT ρg = MW P/ZRT
Viscosity μ1 = AeB/T Negligible Significant only for >10 bar
Vapor pressure P* = aeb/(T+c) – – –

Note: T is temperature (K), Tc is the critical Temperature (K), Tb is the normal boiling point (K), MV is molecular weight, P is pressure, Z is compressibility, R is the gas constant, and P* is the vapor pressure.

Source: Turton, R. et al., Analysis, Synthesis, and Design of Chemical Processes, Prentice Hall International Series, 2001.

Capacities of Process Units in Common Usagea.

Process unit Capacity unit Maximum value Minimum value Comment
Horizontal vessel Pressure (bar) 400 Vacuum L/D typically 2–5
Temperature (°C) 400b −200
Height (m) 10 2
Diameter (m) 2 0.3
L/D 5 2
Vertical vessel Pressure (bar) 400 400 L/D typically 2–5
Temperature (°C) 400b −200
Height (m) 10 2
Diameter (m) 2 0.3
L/D 5 2
Towers Pressure (bar) 400 Vacuum Normal Limits Diameter L/D
Temperature (°C) 400b −200 0.5 3.0–40c
Height (m) 50 2 1.0 2.5–30c
Diameter (m) 4 0.3 2.0 1.6–23c
L/D 30 2 4.0 1.8–13c
Pumps
Reciprocating Powerd (kW) 250 <0.1
Pressure (bar) 1000
Rotary and positive Powerd (kW) 150 <0.1
Displacement Pressure (bar) 300
Centrifugal Powerd (kW) 250 <0.1
Pressure (bar) 300
Compressors
Axial, Centrifugal + Recipr. Powerd (kW) 8000 50
Rotary Powerd (kW) 1000 50
Drives for compressor
Electric Powere (kW) 15,000 <1
Steam turbine Powere (kW) 15,000 100
Gas turbine Powere (kW) 15,000 10
Internal combustion eng. Powere (kW) 15,000 10
Process heaters Duty (MJ/h) 500,000 10,000 Duties different for reactive heaters/furnaces
Heat exchangers Area (m2) 1000 10 For Area <10 m2 use
Tube Dia. (m) 0.0254 0.019 double-pipe exchanger
Length (m) 6.5 2.5
Pressure (bar) 150 Vacuum For 150 < P < 400 bar
Temperature (°C) 400b −200 need special design

aMost of the limits for equipment sizes shown here correspond to the limits used in the costing program (CAPCOST.BAS).

bMaximum temperature and pressure are related to the materials of construction and may differ from values shown here.

cFor 20 <L/D < 30 special design may be required. Diameter up to 7 m possible but over 4 m must be fabricated on site.

dPower values refer to fluid/pumping power.

ePower values refer to shaft power.

Source: Turton, R. et al., Analysis, Synthesis, and Design of Chemical Processes, Prentice Hall International Series, 2001.

Effect of Typical Materials of Construction on Product Color, Corrosion, Abrasion, and Catalytic Effects .

Metals
Material Advantages Disadvantages
Carbon steel Low cost, readily available, resists abrasion, standard fabrication, resists alkali Poor resistance to acids and strong alkali, often causes discoloration and contamination
Stainless steel Resists most acids, reduces discoloration, available with a variety of alloys, abrasion less than mild steel Not resistant to chlorides, more expensive, fabrication more difficult, alloy materials may have catalytic effects
Monel–Nickel Little discoloration, contamination, resistant to chlorides Not resistant to oxidizing environments, expensive
Hasteloy Improved over Monel–Nickel More expensive than Monel–Nickel
Other exotic metals Improves specific properties Very high cost
Non-metals
Glass Useful in laboratory and batch system, low diffusion at walls Fragile, not resistant to high alkali, poor heat transfer, poor abrasion resistance
Plastics Good at low temperature, large variety to select from with various characteristics, easy to fabricate, seldom discolors, minor catalytic effects possible Poor at high temperature, low strength, not resistant to high alkali conditions, low heat transfer, low cost
Ceramics Withstands high temperatures, variety of formulations available, modest cost Poor abrasion properties, high diffusion at walls (in particular hydrogen), low heat transfer, may encourage catalytic reactions

Source: Turton, R. et al., Analysis, Synthesis, and Design of Chemical Processes, Prentice Hall International Series, 2001.

Petroleum Refining Design and Applications Handbook

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