- shallow bed
- shape factor
- shape selective catalysis
- shape selectivity
- shear stress
- shell [side] pass
- shell-and-tube heat exchanger
- Sherwood number
- shortcut method
- shrinking core model
- side cooler
- side heater
- side reaction
- sieve diameter
- sieve tray
- sieve-bend screen
- signal flow diagram
- simple reaction
- simplex method
- simulated annealing
- simulated moving bed adsorption
- simulation
- simulator
- simultaneous correction method
- simultaneous reaction
- single cell protein, SCP
- single crystal
- single reaction
- single screw extruder
- single-phase flow
- sintered material
- sintering
- size classification
- size reduction
- slack variable
- sludge
- slug flow
- slugging
- sluice separation
- slurry reactor
- slurry, pulp
- smoke
- Soave RK equation,SRK equation
- solid state fermentation
- solid-liquid equilibrium, SLE
- solid-liquid separation
- solidus
- solubility
- solubility parameter
- solubility product