Batch and Continuous

Batch and continuous distillation are particularly efficient where a high-quality distillate is required for the very highest purity. Both can employ cryogenic distillation as an option.

Batch and Continuous Distillation

The Internal Reflux Distillation Column combines mass and heat transfer to efficiently separate and purify streams. This flexible solution minimizes recycled fractions and start-up time, achieving the highest purity and FDA compliance.

An Internal Reflux Column is specifically adopted in solvent recovery from complex mixtures, where the results of other available techniques are inadequate or result in an economically inconvenient recovery.

Cryogenic distillation is an option.

Versatile Solutions

Our plants are versatile, allowing us to design the recovery processes according to specific project requirements, on a case-by-case basis. We have successfully utilized internal reflux distillation for the following processes:

  • distillation at pressures less than, equal to, or more than atmospheric pressure
  • distillation under high vacuum
  • azeotropic distillation
  • extractive distillation
  • de-hydration by distillation with phase separation

It is possible to fractionate with variable or constant internal reflux for each of the options above.


  1. Quick start-up: Just minutes after the mixture starts boiling in the still, boiling vapors reach the top and steady-state operation is established.
  1. Minimization of recycled fractions: The Internal Reflux Distillation Column has no dead points or hold-up of distillate fractions, which could contaminate the next distillate fractions (like the external condenser, reflux accumulator, column distributor, or trays, etc.). This minimizes the transitory phases from one product to the next and increases recovery yields.
    • This is particularly impactful in an industry where challenges arise as a result of chemico-physical interactions and affinity between the compounds present in the mixture. The stronger the affinity, the more difficult the separation will be. Significant quantities of off-spec fractions are thus produced, reducing the recovery yield and the overall system net capacity, and increasing the cost of recovery.
    • With the internal reflux column, it is possible to get selective separation of components of extremely complex mixtures, with similar chemico-physical characteristics, which are not economically separable otherwise.
  1. Reduced contamination: An automatic clean in place (CIP) cycle can be added by introducing steam in the column coils. This ensures that the very few tails of distillate product adhering to the column surface are physically evaporated and drained at the column bottom into a separate tank, which can be recycled. The overall quantities of “heads” and “tails” are thus significantly reduced – reaching levels that are less than 5 % of what remains after all other conventional distillation techniques.
    • As this CIP does not produce wastewater, the validation of the unit by the internal QHSE department, as well as by external agencies, is easier – in particular for multi-purpose units in pharmaceutical applications.
  1. Solvent Separation: The Internal Reflux Column can be designed for top-reactor (for organic synthesis) installation to separate solvents during distillation phases (even under a vacuum or during a reaction), remove solvents quantitatively and selectively based on their volatility, and leave only the solvents required by the process functionality inside the reactor. This result cannot be obtained with a simple condenser. Successful applications of the internal reflux column demonstrate an increased yield, quality, and production
  1. Reduced Waste Costs: The Polaris Internal Reflux Column can reduce the waste disposal costs of solvents and water mixtures, with a recovery otherwise not economically justified. In this case the system:
    • separates the organic solvents from water, producing mixtures that can be sold in the market as diluents or as fuel
    • separates water with COD levels below regulated limits in order to send the same to public sewer or water collection
    • minimizes the residual fraction of non-recovered mixtures to be disposed of by third parties.
  1. Heat Recovery: The cooling fluid that circulates in the column coils exits at a temperature close to the still temperature (at boiling point), which is an important thermal gradient that can be considered for heat recovery. This heat recovery can decrease operating costs.

Typical Plant Configuration

  • The plant is a multi-purpose rectification unit, which can be used for solvent recovery from several mixtures (mother liquors of synthesis processes, centrifugation, drying, etc.), is easy to operate, and is very flexible in use. The unit, in its more complete configuration, includes:
    • the still
    • the reboiler
    • the rectification column
    • condenser(s)
    • a gravity phase separator
    • one vacuum pump (if under vacuum)
    • related instrumentation
    • a control system
  • The plant is skid mounted and supplied as a packaged unit.

Batch and Continuous

Cryogenic Distillation

Our cryogenic distillation plant uses cryogenic temperatures to obtain ultra-pure gases. The process is highly flexible and can be used for the supply of gas with purity ranging from 2.5 up to 5.5 grade and for the highest yield.

  • High Purity
  • Reusable gas
  • Optimized costs


  • The process can be applied either for continuous or batch production and the degree of automation can be customized based on customer requests.
  • The system can also be designed as a multipurpose distillation plant for several components of the purification process in different batches.

Machine Characteristics

  1. High Product Purity: The high purity of products is achieved through the use of at least 2 sequential columns. This design allows for the possibility of selective elimination of both heavy and light compounds, while also maintaining a low OPEX cost.
  2. Reusable Gas: The pressure drop is minimized, thus allowing the customer to easily re-use the purified gas. For some compounds, an additional compressor can be installed to optimize the distillation process.
  3. Optimized Costs: Thanks to the efficient use of a heating and cooling method, and to a compact footprint, CAPEX and OPEX are optimized, making the investment sustainable even with low flowrates.

Typical Plant Configuration

  • Impact on the customer site is negligible, since the plant is mainly composed of a cold box and, depending on operating conditions, a pre-treatment section.
  • The plant is skid mounted and supplied as a packaged unit.