Milk Falling Film Evaporator & MVR Economy Calculator
Model falling film evaporation rates, concentrate solids, Mechanical Vapor Recompression (MVR) electrical duties, and multi-effect steam economies.
Feed & Concentrate Solids
Evaporator Technology & Utilities
Evaporative Capacity & Output
Thermal Economy Diagnostics
Recommended Tools & Equipment
Tested hardware and components for high reliability
Engineering Fundamentals: Dairy Falling Film Evaporators & MVR Technology
Pre-concentrating milk and whey before spray drying is essential because evaporating water in a falling film evaporator consumes less than 10% of the energy required to evaporate it in a hot-air spray drying tower.
1. Mass Balance Formulations
M_solids = Feed × (S_in / 100) (kg/h)M_concentrate = M_solids / (S_out / 100) (kg/h)W_evap = Feed - M_concentrate (kg/h water removed)
2. MVR (Mechanical Vapor Recompression) vs. TVR Steam
In an MVR evaporator, all vapors boiled off the milk are compressed by a high-speed centrifugal turbo-fan, raising saturation temperature by 4°C to 7°C. The compressed vapor is then returned to the shell side of the calandria as the primary heating medium, condensing and releasing latent heat back into the falling film. MVR consumes only 8 to 12 kWh of electricity per tonne of water evaporated, rendering traditional multi-effect steam evaporators obsolete in modern dairy manufacturing.
Frequently Asked Questions
Why is milk pre-concentrated in a falling film evaporator before spray drying?
A modern MVR falling film evaporator evaporates 1,000 kg of water using roughly 10 kWh of electricity ($0.90 to $1.20). In contrast, evaporating that same 1,000 kg of water in a natural-gas fired spray dryer costs $25 to $35. Removing 80% of water in the evaporator cuts powder production energy costs by over 75%.
How does Mechanical Vapor Recompression (MVR) work in dairy evaporation?
MVR uses an electrically driven high-speed centrifugal compressor (turbo-fan) to compress the low-pressure water vapors leaving the separator. Compression raises the vapor temperature by 4°C to 7°C, allowing the vapor to be re-injected as the primary heating steam into the calandria tubes, eliminating the need for continuous boiler steam.
What is the maximum concentrate solids achievable before spray drying milk?
Skim milk and whole milk are typically concentrated to 48% to 52% total solids in falling film evaporators. Exceeding 54% solids causes exponential viscosity spikes, fouling calandria tubes, and causing atomization plugging in spray drying nozzles.
Why are falling film evaporators operated under vacuum?
Milk is extremely heat-sensitive; proteins (whey lactoglobulin and casein) denature and foul heating surfaces at elevated temperatures. Under deep vacuum (e.g. 0.15 to 0.25 bar absolute), milk boils gently between 55°C and 65°C (131°F–149°F), preserving nutritional value, solubility, and flavor.