Rectification batch

Rectification batch2020-06-08T16:36:38+02:00

Batch rectification with & without film evaporator, System ERB

Stirred tank evaporators or batch evaporators are used for the distillative fractionation of a batch mixture in the stirred tank. The aim is to obtain one or more distillate fractions and the remaining concentrate in the stirred tank in the required purity. If the boiling points of the components are close to each other, simple evaporation is not sufficient; a rectification column is required as an attachment on top of the stirred tank to achieve higher purities. This is illustrated in the schematic of the ERB system shown above: The starting solution is placed in the stirred tank, possibly first mixed or chemically converted in a rectification stage, and then partially evaporated by heating the stirred tank. From the initial mixture, the three distillate fractions in V01, V02 and V03 are obtained one after the other – first the low-boiling component, then the higher-boiling fractions. The internals of the rectification column, usually highly efficient structured packings, the hold-up minimized design and the adjustment of the reflux ratio according to the temperature profile along the column ensure on the one hand the required purity and on the other hand the lowest possible waste between the fractions.

Especially for temperature-sensitive solutions, which should only be tempered for as short a time as possible, and for very large solvent contents in the initial mixture, considerably shorter distillation times and thus gentler conditions can be achieved with the ERBF system with an additional external circulation with falling film evaporator. In principle, there are numerous variants of this design which are process-specific and are discussed with the customer.

Vacuum pumps are used to set the desired process conditions (pressure & temperature) and 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-path evaporator can also be connected downstream in a modular fashion.

  • Batchwise combined evaporation and rectification for distillative fractionation for
    • Laboratory and pilot systems made of stainless steel with borosilicate glass 3.3 in standardized modular design, optional process and customer-specific adaptations
    • Production systems made of stainless steel in process- and customer-specific design
  • Modular supplementary evaporator systems according to process requirements, e.g.
    • Downstream evaporators, e.g. system ETF-ESF
    • Vapour rectification column, EFR system
  • Process and customer-specific guidelines, e.g. ATEX, DGRL, FDA, GAMP, ASME, UL standards
  • Suitable for media with increased demands:
    • Mixtures of several components to be separated from each other by distillation, which have to be processed in batches
    • Heat sensitive media
    • Media containing solids
    • Small and large batch quantities
  • Feasibility studies with tests and verification of scale-up or existing expertise for typical applications
    • Special chemicals and agrochemicals
    • Pharmaceutical and cosmetic products
    • Pharmaceutical and cosmetic products
    • Numerous other products from the fine chemicals and pharmaceuticals sector

Laboratory / Pilot systems and preliminary tests

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

Once the basic 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 applicatory 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, smell, foam, solids, …) Consideration of the system behaviour (colour, smell, 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

Bereich Option
  • Permitted operating conditions (product)
    …../..… barg & ..…/….. °C
  • ATEX-Directive 2014/34EU,
    EX-Zone …../..… (inside/outside), II ..…, T ..…
  • GMP-Directives
  • Other directives: …….………………………….
  • G – Stainless steel (1.4571/1.4404) / Borosilicate glass 3.3
  • S – Stainless steel (1.4571/1.4404)
  • X – Alternative material: …….………………………….
  • E1S – Single-pass evaporator
  • E1M – Multi-pass Evaporator, Number of passes: …….
  • E2X – Energy recovery, alternative: ………………………
Vacuum system
  • V1 – Rotary vane pump, ca. 0,1 – 10 mbara
  • V2 – Membrane vacuum pump, ca. 10 – 1.000 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 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 control 1)
  • 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

Batcg 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 stirred tank rectification column on a production scale are individually dimensioned for the customer processes, the typical dimensions are in the range of a few litres up to more than 10 m³ batch volume. For larger plants, we try to integrate a heat recovery system suitable for the respective process, for example by preheating the feed stream with hot product streams or using the distillate stream.

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.

Technical specification

Typ of Batch-


Area Material Batch volume /

Heat exchange surface

Column diameter1) Condensator Optional

Falling film

evaporator 2)

[l / m²] [mm] [m²] [m²]
ERB 020-G Lab SS / Boro 3.3 20 l / 0,3 m² 50 / 80 1 m²
ERB 050 -S Pilot /
Small batch
SS 50 l / 0,6 m² 80 / 100 1,5 m² 1,5 m²
ERB 100 -S Pilot /
Small batch
SS 100 l / 1,0 m² 80 / 100 / 150 2,5 m² 2,0 m²
ERB 250 -S Pilot /
Small batch
SS 250 l / 1,8 m² 100 / 150 / 200 /300 4,0 m² 4,0 m²
ERB …-S Production SS >500 l,
on request
on request on request on request

1) Typical column diameter, determined according to operating conditions (especially pressure) System conditions (especially low boiling fraction in the feed and required return flow rate)

2) Typical evaporator size, determined according to operating conditions (especially temperature difference and required evaporation rate)

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