Process Equipment and Plant Design
In a vertical short tube evaporator (Calendria type), the

Area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube
Liquor is inside the tube while the steam is outside the tube
Tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used
All of these

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Process Equipment and Plant Design
Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 - 1.4 cp and relative volatility < 4) (where η = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi)

Η = 0.25 log μ - 1.67
Η = 17 - 61.1 log μ
Η = 1.66 - 0.25 log μ
Η = 24.6 (Δp/μ)

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