Shell and Tube Heat Exchangers
Tube size:
Length is standard, commonly 8, 12 or 16 ft.
Diameter: most common 3/4 or 1 in OD
Tube pitch and clearance:
Pitch is the shortest center-to-center distance between adjacent tubes. Commonly 1.25 to 1.5 times the tube diameter. Clearance is the distance between tubes. It should be larger Than 25% of the tube diameter. Triangular or square arrangement of tubes are quite Common.
Baffles:
Baffles are usually spaced between 20% and 100% of the ID of the shell.
Fluid location:
Corrosive fluids flow inside the tubes.
Fluid with higher fouling tendency inside the tubes.
High pressure fluid inside the tubes (if everything else the same).
Hot fluid inside the tubes.
Typical velocities:
Liquids: 1-2 m/s in tubes, max 4 m/s to reduce fouling.
0.3 to 1 m/s in shell
Vapors: 50-70 m/s (vacuum)
Shell:
Up to 24 in nominal size, use standard pipes.
Passes:
Most usual pass is one (type E according to TEMA standards). Split flow arrangement (types G and J) is used for pressure drop reduction, when the pressure drop is the controlling factor in the design