...everything in control
 › Products › Evaporation & Rectification › Rectification continuous

Rectification continuous

Continuous rectification with film evaporator

Process chart


Film evaporators with rectification are used for gentle partial evaporation of liquid mixtures whose high-boiling fraction has components with boiling points close to those of the distillate to be separated. The rectification column achieves a depletion of these components from the distillate and vice versa of the low boiling point from the concentrate and thus purer distillate and concentrate fractions.

Often these processes have to be carried out at low operating pressures, for example to enable gentler temperature conditions for high boilers, and require the advantages of film evaporator systems. The falling film evaporator based system ERF is preferably used for larger feed quantities and the thin film evaporator system ERT for short dwell times and further enrichment in the sump area.

The raw solution is fed into the evaporator or column and evenly distributed as a thin film over the surface of the evaporator tubes or column packing using a special distribution system. From the liquid stream flowing into the vaporizer, the light boilers are partially evaporated and fed into the column where vapor and liquid are in countercurrent contact and a high separation efficiency is achieved by built-in components.

The distillate depleted of secondary components is liquefied in the condenser E03 and, after recirculation of the required quantity of reflux, is either collected as distillate in a receiver tank or continuously discharged via a pump P03. Similarly, the concentrate is discharged from the evaporator using pump P02.

Vacuum pumps are used to set the desired process conditions (pressure & temperature).Thermostats (laboratory and pilot scale) and classical energy sources (production scale) are used for heating, evaporation and condensation. A cold trap is used to reduce undesired entry of low boilers from the exhaust gas flow into the vacuum pump.

Depending on the application and process requirements, further units such as an exhaust gas scrubber or short film evaporator can also be connected downstream in a modular fashion.

  • Combined evaporation and rectification systems with low hold-up and gentle operating conditions for
    • Laboratory and pilot systems made of stainless steel and 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. system EFF-ETF, or Flash-Box
    • Rectification column for concentration of vapours, system ETR
  • Process and customer-specific guidelines, e.g. ATEX, DGRL, FDA, GAMP, ASME, UL standards.
  • Suitable for media with increased demands:
    • Mixtures with high boilers and components with close boiling points
    • Low-viscosity media
    • Heat-sensitive media
    • Larger feed volumes
  • Existing expertise for typical applications or feasibility studies with tests and scale-up verification
    • Specialty and agrochemicals
    • Pharmaceuticals and cosmetics
    • Flavours and fragrances
    • Food / Additives
    • Fatty acids
    • Various other products of the fine chemicals and pharmaceuticals sector

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 systems and options for laboratory and pilot systems

In addition, there are numerous available options listed below. The options do not represent a complete characterization, but are intended to show the possibilities for the customer and to support the efficient development of a concept for feasibility, as far as the characterization is not done by the questionnaire for evaporation processes.

Options for batch rectification systems

Area Option
  • Permitted operating conditions (product) …../..… barg & ..…/….. °C
  • ATEX-Directive 2014/34EU, EX-Zone …../..… (inside/outside), II ..…, T…..
  • GMP-Directive
  • 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: …….………………………….
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, Boro 3.3, for dry ice or liquid nitrogen
  • C2 – Cold trap, Boro 3.3, for dry ice or liquid nitrogen
  • C3 – Cold trap, SS/Boro 3.3, electric
Discharge 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

Verdampfer Rohrsystem

Film evaporator rectification systems are realized on a production scale for many known applications and also for numerous new processes that have been dimensioned in advance through studies and tests. The production plants are preferably designed as package units. This reduces the planning effort on the one hand and, in particular, the installation and commissioning time at the customer’s site on the other.

The combi-systems evaporator-column on a production scale are individually dimensioned for the customer processes, the typical and most common evaporator sizes range from 2.5 m² to more than 100 m² and column diameters from nominal size DN 200 to DN 1500. For larger plants we attempt to integrate a heat recovery system suitable for the respective process, for example by preheating the feed stream with hot product streams or multi-stage evaporation or, in the case of closely spaced distillate and concentrate temperatures, by mechanical vapour recompression.

In some cases, specific cyclical cleaning processes are also required, which we would be pleased to develop together with you.

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

Operation is typically carried out at temperatures up to 250 °C in the vaporiser and working pressures up to 1 mbar absolute at the column head. This includes laboratory and pilot scale operation.



Technichal specification of laboratory and pilot evaporators




Exchange surface /Diameter

Evaporator length heated

Number of tubes Evaporator




Throughput Feed

Lab ERF 010-G 0,1 m² / DN 25
Single pipe
1.000 mm
1 50 / 80 mm Stainless steel / Boro 3.3 0,5 – 6 [kg/h]
Lab ERT 006-G 0,06 m² / DN 80 -
50 / 80 mm  Stainless steel / Boro 3.3 1 – 6 [kg/h]
Lab / Pilot ERF 040 -S 0,4 m² / DN 80
Single pipe
1.500 mm
1 80 / 100 / 150 mm Stainless steel / Boro 3.3 1,5 – 18 [kg/h]
Lab / Pilot ERT 030 -S 0,3 m² / DN 200 - 1 80 / 100 / 150 mm Stainless steel 5 – 30 [kg/h]
Pilot / Small batch ERF 350 -S 3,5 m² / DN 200
Multiple pipe
2.000 mm
19 150 / 200 / 300 mm Stainless steel 20 – 200 [kg/h]
Pilot / Small batch ERT 060 -S 0,6 m² / DN 250 -
150 / 200 / 300 mm Stainless steel 10 – 60 [kg/h]
Production ERF …-S
>1 m², typical
– 1,5 m² to 10 m²
– DN 300 – DN1000
1.200 mm – 4.000 mm
on request Stainless steel on request


1) Typical column diameter, depending on operating conditions (especially pressure) System conditions (especially low-boiling fraction in the feed and required return flow rate)




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