In a forward-feed evaporator arrangement, feed enters the first effect at the highest temperature and pressure. When the raw feed is already hot (near the boiling point of effect 1), no live steam is wasted on preheating the feed; furthermore, as liquor flows into subsequent lower-pressure effects, it flashes automatically, maximizing total steam economy.

During spray drying of milk droplets, pure moisture evaporates rapidly from the droplet surface in the constant-rate drying period. The droplet temperature naturally stabilizes at the wet-bulb temperature of the drying air (typically $40^\circ\text{C} - 50^\circ\text{C}$), protecting heat-sensitive milk proteins even though the drying air dry-bulb temperature is $180^\circ\text{C} - 200^\circ\text{C}$.

Types and construction of vertical evaporators:

• Short-tube vertical evaporators, featuring vertical tubes ($1\text{--}2\text{ m}$ in length) expanded into tube sheets with a large central downtake, are universally termed Calandria evaporators or standard evaporators.
• Plate evaporators utilize gasketed plate assemblies instead of tube bundles.
• Compression evaporators employ mechanical vapour compressors.
• Direct evaporators rely on submerged combustion or direct heating.