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Short Path Evaporation

Short film evaporation

Short path evaporation process chart

The Short Film Evaporator System ESF is used for gentle partial evaporation of liquid mixtures, especially when requirements – e.g. high viscosities or very short dwell times – exceed the capabilities of classic evaporators and of the falling film and thin film evaporator systems EFF and ETF.

The raw solution is fed from a feed batch vessel or continuously into the evaporator. A wiper system distributes it evenly around the circumference as a thin film. The low boilers are then partially evaporated from the film flowing down and constantly redistributed on the evaporator surface by the wiper system, condense as distillate on the internal condenser and flow off from there. Similarly, the concentrate exits the evaporator along the heated wall. The distillate and concentrate are either collected in a receiver tank or continuously discharged by a pump.

Vacuum pumps are used to set the desired process conditions such as pressure and temperature. Thermostats (laboratory and pilot scale) are used for heating, evaporation and condensation. On a production scale, classic energy sources such as steam, thermal oil respectively cooling water, brine and glycol are used. A cold trap is used to reduce the undesired entry of low boilers from the exhaust gas flow into the vacuum pump system.

  • Evaporators with low hold-up and corresponding short dwell time with narrow dwell time distribution and gentle operating conditions for
    • Laboratory and pilot systems made of stainless steel with borosilicate glass 3.3 in standardized design, optional process-specific adaptations
    • Production systems made of stainless steel in process- and customer-specific design
  • Modular supplementary evaporator systems according to process requirements, e.g.
    • Upstream and downstream evaporators, e.g. EFF-ETF system
    • Flash-Box
  • Process and customer-specific guidelines, e.g. ATEX, PED, FDA, GMP, ASME, UL standards
  • Suitable for media with increased demands:
    • Viscous and highly viscous media
    • Heat-sensitive media
    • Solids-containing media
    • Higher-melting media
  • Feasibility studies or existing expertise for typical applications
    • Fatty acids and fatty acid derivatives
    • By-products from the production of edible oil
    • Special polymers or oligomers
    • Pharmaceutical and cosmetic products
    • Specialty chemicals
    • Fragrances and flavourings

Laboratory and pilot evaporator systems and prelminiary test

Labor mit Instrumenten

For many applications, in addition to the composition of distillate and/or residue or concentrate, product properties such as odour and colour are also relevant. Likewise, possible effects that may occur during evaporation, such as foaming or fouling on the heat exchanger surface, must be taken into account. The latter cannot be determined or estimated theoretically, but require a visual evaluation of the evaporation process. This can best be implemented in glass plants from COROSYS, which can be individually assembled in a modular system.

Once the general feasibility has been established, the process parameters for the design of a production plant shall be verified, i.e. heat transfer and maximum area-related evaporation rates or practical number of stages as well as the achievable yields and qualities shall be determined. For this purpose, COROSYS has a standardized series of pilot plants made of stainless steel (optionally also special materials) in various sizes and designs to choose from.

For new evaporation or distillation tasks, COROSYS offers in-house services ranging from literature research, thermodynamic simulations and laboratory tests to piloting of single systems or combinations of falling film (EFF), thin film (ETF) and short path evaporators (ESF), if necessary also in combination with rectification (ERF).

The main objectives and possibilities of preliminary studies/test distillations as well as laboratory and pilot plants are again briefly and clearly summarized in the following table:

Pre-studies / Test distillations Laboratory Systems Pilot systems
Literature/Patent research, determination of substance data, themodynamic modelling of evaporation/rectification Feasibility check Detailed process data determination based on feasibility study and preselected  evaporator system
Stainless steel with borosilicate glass 3.3 Stainless steel with borosilicate glass 3.3,
optionally other materials
Stainless steel,
optionally other materials
Tests to determine feasibility / selectivity Laboratory tests mostly with a pre-selected film evaporator system Engineering of the production plant with dimensioning of apparatuses and media
Comparison of the different film evaporator systems and subsequent pre-selection Determination of the straightening process parameters and achievable yields and qualities Detailed determination of process parameters and achievable yields and qualities
Visual evaluation of system behaviour (colour, smell, foam, solids, deposits, …) Consideration and visual evaluation of the system behaviour (colour, odour, foam, solids, …) Consideration of the system behaviour (colour, odour, foam, solids, deposits, …)
Coordination of the analytics Sample quantities or very small production quantities Larger sample quantities or small production quantities

Standard modules and options

Short Film Evaporators for laboratory and pilot applications can be assembled from numerous modules and options listed in the table below. For a detailed characterization with process requirements, the questionnaire for evaporator processes is available as a supplement.

Technical specification of industrial evaporators

Area Evaporator Exchange surface Diameter Heated length Material Feed dimension
Lab ETF 0002-G 0,02 m² DN 40 160 mm
Stainless steel / Boro 3.3 0,03 – 0,6 [kg/h]
Lab ETF 0006-G 0,06 m² DN 80 240 mm
Stainless steel / Boro 3.3 0,2 – 1,5 [kg/h]
Pilot ETF 0006-S 0,06 m² DN 80 240 mm
Stainless steel 0,2 – 6,0  [kg/h]
Pilot ETF 0012-S 0,12 m² DN 125 310 mm
Stainless steel 1,0 – 12 [kg/h]
Pilot ETF 0030-S 0,3 m² DN 200 480 mm
Stainless steel 2,0 – 30 [kg/h]
Pilot ETF 0060-S 0,6 m² DN 250 760 mm
Stainless steel 2,5 – 60 [kg/h]


Area Option
  • Permitted operating conditions (product) …../..… barg & ..…/….. °C
  • ATEX-Directive 2014/34EU,EX-Zone …../..… (inside/outside), II…, T…
  • FDA-Directives
  • Other directives: …….………………………….
  • G – Stainless steel (1.4571/1.4404) / Borosilicate glass 3.3
  • S – Stainless steel (1.4571/1.4404)
  • X – Alternative material: …….………………………….
  • F1 – Dropping funnel
  • F2 – Pump
  • F3 – Feed vessel for pump operation
  • F5 – Flash-Box for pump operation
  • FX – Other feed options: …….………………………….
  • E1R – Wiper and distributor system, rolling
  • E1P – Wiper and distributor system, profiled
  • E2L – Shaft sealing ring
  • E2M – Magnetic coupling
  • E2X – Other shaft sealing system: …….………………………….
  • E3G – Gravimetric discharge
  • E3S – Optional discharge via screw conveyor
Vacuum system
  • V1 – Rotary vane pump, ca. 0,1 – 10 mbara
  • V2 – Membrane vacuum pump, ca. 10 – 1.000 mbara
  • V3 – Oil diffusion pump, ca. 0,1 – 10 mbara
  • VX – Combination of other vacuum pumps, desired volume: ..… Nm³/h and operation pressure : ..… mbara
Cold trap
  • C1 – Cold trap, Borosilicate Glass 3.3, for dry ice or liquid nitrogen
  • C2 – Cold trap, Borosilicate Glass 3.3, for dry ice or liquid nitrogen
  • C3 – Cold trap, Stainless Steel/Borosilicate Glass 3.3, electric
Discharge of concentrate & distillate
  • A1 – Discharge in distilling receiver acc. to Bredt-type collector (triple)
  • A2 – Discharge in glass bulb
  • A3 – Discharge in measuring vessel
  • A4 – Discharge via pump
Temperature control1)
  • T1Y – Feed Y = T, S, E   …………°C
  • T2Y – Evaporator Y = T, S      …………°C
  • T3Y – Condensator Y = C, CW  …………°C
  • T4Y – Cold trap Y = CW, E   …………°C
  • T5Y – Discharge distillate Y = C, CW  …………°C
  • T6Y – Discharge concentrate Y = C, CW  …………°C
  • TXY – Other … Y = ….        …………°C
  • S1 – Stainless steel frame, wheeled, with drip tray, L, P without protective cladding
  • S1X – Desired variations: …….………………………….
  • S2 – Manual operation, local display of temperature & pressure, L, P, Emergency stop
  • S2X – Desired variations: …….………………………….

1) T = Thermostat S= Steam E=Electrical C= Cooling Media CW=Cooling Water

Production-scale evaporator systems


Produktion Rohrsystem

Production plants are usually designed for specific processes, usually on the basis of pilot tests. Typical evaporation capacities of industrial ESF evaporators start from a few kilograms up to several tons per hour. Depending on the product and task, different wiper systems are available. The wiper systems are overhung, optionally equipped with dynamic droplet separators as well as a double-acting mechanical seal to protect the wiper basket shaft from the atmosphere. In principle, fine machining of the surfaces in contact with product and the use of alternative materials are also possible.

The production plants are preferably designed as package units, which on the one hand reduces the customers’ planning effort and on the other hand especially the time required for installation and commissioning on site at the customer.

The construction of the production systems is carried out in compliance with the necessary directives such as PED 2014/68 EU or ASME, ATEX 2014/34 EU, UL standards, GMP guidelines, TA-Luft and the machinery directive 2006/42/EG.

Technical specification laboratory and pilot evaporators


Area Evaporator Exchange surface Diameter  Heated Length Total Length Material

Exchange surface

Industry ETF 0150-S 1,5 m² DN 300 1.195 mm
2.865 mm Stainless steel 3,0 m²
Industry TF 0200-S 2,0 m² DN 400 1.590 mm
3.260mm Stainless steel 4,0 m²
Industry ETF 0300-S 3,0 m² DN 700 1.365 mm
3.765 mm Stainless steel 9,0 m²
Industry ETF 0400-S 4,0 m² DN 700 1820 mm 4.220 mm Stainless steel 12,0 m²
Industry ETF 0600-S 6,0 m² DN 700 2.730 mm
5.130 mm Stainless steel 16,0 m²
Industry ETF 0900-S 9,0 m² DN 1000 2.870 mm
5.595 mm Stainless steel 22,0 m²
Industry ETF 1200-S 12,0 m² DN 1000 3.820 mm
6.650 mm Stainless steel 28,0 m²

Larger evaporators on request.

Contact us
Do you have any questions?
Dr. Lukas Karst
Contact Engineering
Dr. Lukas Karst
Project Engineering

Phone: +49 6122 / 70 75 - 0
Email lukas.karst@corosys.com

Contact Engineering.
Dr. Lukas Karst
Dr. Lukas Karst
Project Engineering

Phone: +49 6122 / 70 75 - 0
Email lukas.karst@corosys.com