Process Equipment Design

Pressure-vessel wall thickness is sized so the hoop stress stays below the allowable stress times the joint efficiency; because hoop stress is twice the longitudinal stress, the circumferential seam governs a cylindrical shell.

Shell-and-tube design first finds the area from the duty, overall coefficient and corrected LMTD, then lays out the tube bundle (count, length, pitch) and baffling to achieve that area within acceptable pressure drops on both sides.

Column internals are sized so the vapour velocity stays safely below the Souders-Brown flooding velocity; trays are rated by their hydraulic limits while packed columns are rated by the height equivalent to a theoretical plate (HETP).

Agitator power scales as N_p·ρ·N³·D⁵, so power is extremely sensitive to impeller speed and diameter; the power number itself depends on the impeller type and on whether the flow is laminar or turbulent (via the impeller Reynolds number).

Piping design selects a pipe diameter that balances pumping cost (favouring larger, lower-velocity lines) against capital cost (favouring smaller lines), then checks pressure drop from friction and fittings and provides for thermal expansion.