Evaporation Equipment

Falling Film Evaporator

Mechotech engineers and manufactures the Falling Film Evaporator as turnkey process equipment that concentrates moderate-viscosity, non-fouling liquids by letting the feed descend as a thin gravity-driven film down the inside wall of heated vertical tubes. Because the film is thin and constantly renewed by gravity and the co-current vapour flow, residence time on the heated surface is very short and the temperature differential needed to drive evaporation is small, making this the most thermally efficient and steam-economical evaporator geometry for feeds that do not scale, crystallize, or thicken sharply as they concentrate.

Feed is distributed across the tube sheet through a calibrated distributor plate or spray nozzles so every tube receives an even liquid load, then falls as a continuous film down the tube bore under gravity while the shell side is heated by steam or hot process fluid; the vapour generated travels downward with the liquid and is separated from the concentrate at the base in a cyclone-type separator. Because heat transfer coefficients on a falling film are high and the driving temperature difference can be kept low, the Falling Film Evaporator is Mechotech's standard choice for large-throughput, single- or first-effect duty ahead of an MEE or MVR train, built in SS 316L (or a process-appropriate grade) with electropolished product-contact surfaces, CIP connections and PLC-based instrumentation. Tube length, tube count, and shell diameter are configured to the specified evaporation load, and the unit is delivered with full documentation to support GMP and regulatory qualification.

Process Flow

Technical Specifications

Evaporator Type	Falling Film Evaporator, vertical tube-bundle geometry
Working Principle	Thin gravity-driven film descends inside heated vertical tubes under co-current vapour flow
Tube Orientation	Vertical, top-fed
Heating Medium	Steam or thermic fluid on the shell side (configurable)
Operating Mode	Vacuum operation (typical) or atmospheric, depending on product heat sensitivity
Feed Distribution	Distributor plate, weir trough, or spray-nozzle distribution
Vapour Separation	Cyclone or baffle-type separator at tube base
Residence Time	Very short — single-pass film contact, minimizing thermal exposure
Suited Feed Character	Moderate-viscosity, non-fouling, non-crystallizing liquids
Product-contact Material	SS 316L (or process-appropriate grade), electropolished
Condensing System	Surface or barometric condenser with vacuum ejector/pump
Automation	PLC-based control of level, temperature, and vacuum (configurable to SCADA)
Cleaning	CIP-capable product-contact circuit
Configuration	Single-effect or as a first effect within an MEE/MVR train
Capacity	Configured to requirement — pilot to large commercial evaporation duty
Utilities	Steam / thermic fluid for shell heating, cooling water, vacuum system utilities, electric power, compressed air
Compliance	GMP/WHO-GMP hygienic design; documentation for regulatory qualification

Plant Capacities

Scale	Typical Duty	Tube Configuration	Effect Arrangement
Pilot	Process validation, low evaporation load	Small tube count, short tube length	Single effect
Mid-size commercial	Plant-scale continuous concentration	Medium tube bundle	Single effect or first effect of MEE
Large commercial	High-throughput continuous evaporation	Large tube bundle, extended tube length	First effect of MEE/MVR train

Tube count, tube length, and shell diameter are engineered to the specified evaporation duty and feed properties; exact heat-transfer area and throughput are confirmed during process design.

Manufacturing Process

Feed Preheating

Incoming feed is preheated, typically against outgoing condensate or vapour, so it enters the tube bundle close to its boiling point and flashing begins immediately rather than consuming tube length on sensible heating.

Film Distribution

A distributor plate, weir trough, or spray nozzles spread the preheated feed evenly across the top tube sheet so every tube in the bundle receives a uniform, unbroken liquid film.

Falling-Film Evaporation

The film descends under gravity down the inside of the heated vertical tubes while steam or hot fluid condenses on the shell side; the short contact time and high film turbulence give rapid, gentle evaporation with minimal thermal exposure.

Vapour-Liquid Separation

Concentrate and vapour leaving the tube base pass into a cyclone or baffle-type separator sized to disengage entrained droplets before the vapour proceeds to the condenser.

Condensation & Vacuum Generation

Vapour is condensed in a surface or barometric condenser; a vacuum system (steam ejector or liquid-ring pump) maintains the operating vacuum that lowers the boiling point and protects heat-sensitive product.

Recirculation or Multi-Pass Operation

For higher concentration ratios the partially concentrated liquid is recirculated through the tube bundle, or routed through successive passes, until the target solids content is reached.

Concentrate Discharge

The concentrated product is withdrawn from the separator sump through a control valve, with level and density instrumentation confirming it meets the target concentration before transfer to storage or the next process step.

CIP & Changeover

The tube bundle, distributor, and separator are cleaned in place between batches or product changeovers, restoring tube-wall wetting performance for the next run.

Major Plant Equipment

Feed preheater
Distributor plate / weir trough / spray-nozzle assembly
Vertical heated tube bundle (calandria)
Shell-side steam/thermic-fluid heating jacket
Cyclone or baffle-type vapour-liquid separator
Concentrate circulation pump (for recirculation duty)
Surface or barometric condenser
Vacuum system (steam ejector or liquid-ring pump)
Condensate receiver and pump-out
Concentrate discharge pump and control valve
CIP skid and spray-ball connections
Instrumentation: level, temperature, pressure/vacuum transmitters
PLC-based control panel with MCC

Plant Output

Concentrated productRecovered vapour condensate

Applications

Fruit and vegetable juice concentration
Dairy concentration (skim milk, whey) ahead of drying
Botanical and herbal extract pre-concentration
Black liquor and industrial effluent concentration
Caustic and process-solution concentration in chemical plants
Pharmaceutical and nutraceutical intermediate concentration
First-effect duty within larger MEE and MVR evaporation trains
Wastewater and RO-reject volume reduction

Key Features

High Heat-Transfer Efficiency
The thin, high-velocity falling film gives high heat-transfer coefficients at a low temperature differential, making this the most steam-economical geometry for suitable feeds.
Short Residence Time
Single-pass film contact on the tube wall minimises thermal exposure, protecting heat-sensitive flavours, colours and bioactives from degradation.
Even Film Distribution
Calibrated distributor plates or spray nozzles maintain a continuous, unbroken film across every tube, preventing dry patches and localized scaling.
Vacuum-Compatible Operation
Operation under vacuum lowers the boiling point for heat-sensitive products and allows multiple falling-film effects to be cascaded in an MEE arrangement.
GMP-Compliant Construction
Electropolished SS 316L product-contact surfaces with CIP connections meet WHO-GMP and Schedule M requirements for regulated-industry production.
Scalable, Multi-Effect Ready
The same tube-bundle geometry scales from pilot validation to large commercial duty and integrates directly as the first effect of an MEE or MVR system.

Frequently Asked Questions

What is a Falling Film Evaporator and how does it work?

A Falling Film Evaporator concentrates a liquid by letting it descend as a thin, gravity-driven film down the inside of heated vertical tubes while steam condenses on the shell side. The thin film and short contact time give high heat-transfer efficiency and gentle thermal exposure, which is why it is the standard choice for large-volume, non-fouling feeds such as juices, dairy streams, and process liquors.

What kind of feed is suited to a Falling Film Evaporator?

It works best on moderate-viscosity, non-fouling, non-crystallizing feeds that flow freely as a film at the operating temperature. For feeds that scale, crystallize, or thicken sharply as they concentrate, Mechotech's Forced Circulation Evaporator is the better fit because it prevents deposit build-up on the heat-transfer surface.

How is a Falling Film Evaporator different from a Rising Film Evaporator?

In a falling film unit the liquid moves downward through the tubes under gravity, assisted by the co-current vapour flow, while in a Rising Film Evaporator the liquid is carried upward by the vapour generated at the base of the tube. Falling film units generally handle a wider viscosity range and higher throughputs, while rising film units are often used for lower-viscosity feeds in the earlier stages of concentration.

Can a Falling Film Evaporator be used as part of a multi-effect system?

Yes. Falling film geometry is the most common building block for MEE Multiple Effect Evaporator trains and for MVR Evaporator systems, because its high heat-transfer coefficient and low temperature-differential requirement make it efficient to cascade across multiple effects for steam economy.

What vacuum level and temperature does the evaporator operate at?

Operating vacuum and corresponding boiling temperature are set to the product's heat sensitivity and the required evaporation rate; most falling-film duties run under vacuum to keep bulk temperatures low. Exact vacuum and temperature set points are established during process design and configured to your feed.

What capacity range can Mechotech supply?

Falling Film Evaporators are engineered from pilot-scale validation skids to large commercial units handling high continuous evaporation loads, with tube count, tube length and shell diameter sized to the confirmed evaporation duty. We recommend validating separation and concentration performance on a pilot unit before committing to full-scale tube-bundle sizing.

Does Mechotech supply the complete Falling Film Evaporator as a turnkey system?

Yes. Mechotech engineers, fabricates, installs and commissions the complete Falling Film Evaporator — tube bundle, separator, condenser, vacuum system and automation — as a single accountable scope, with documentation to support GMP and regulatory qualification.

Ready to discuss your project?

Get a free quote and technical consultation from our engineering team.

Get A Free Quote

Falling Film Evaporator