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Solvent Distillation Systems
Evaporation, Concentration & Solvent Recovery

Solvent Distillation Systems

A solvent distillation system separates a mixed liquid feed into fractions by boiling point, using a still, a column with reflux, a condenser and receivers, so each fraction leaves at its own specification.

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Stainless-steel distillation vessels, columns and condensers inside an installed plant

Solvent Distillation Systems

The feed may be ethanol and water from a botanical line, a drum of mixed solvents or a hexane stream carrying oil, and the plant either splits it into several products or polishes one solvent to a tighter purity. A buyer should settle the components and their boiling points, the vapour-liquid equilibrium data for the mixture, the purity wanted on each fraction, the feed rate per hour and whether the plant runs in batches or continuously. How hard the separation is sets the column height and the reflux, and the condenser and cooling supply, which carry most of the heat put in, set the main utility demand. Flammable solvents also make the classified-area layout a design input. Simple take-back of a spent solvent from an extraction line is the job of the solvent recovery distillation plant.

Feed is filtered or settled so that solids and colour do not foul the plant, then heated in a reboiler. Vapour rises through a column, where it meets liquid running down, and each contact moves the lighter component up and the heavier one down. Part of the condensed overhead returns as reflux and the rest is drawn off as product, so the reflux setting trades purity against energy and throughput. Components with close boiling points need more stages and more reflux, and some mixtures, such as ethanol and water, have an azeotrope that distillation alone cannot pass, which should be agreed with the process owner. Packing gives a low pressure drop and suits vacuum duty, while trays tolerate solids better. A batch column collects cuts in turn and suits varied campaigns and small volumes; a continuous column suits a steady feed with one separation. Reduced pressure lowers boiling temperatures for heat-sensitive or high-boiling feeds. Most of the heat put into the reboiler leaves at the condenser, so cooling water, air cooling or a chilled loop is a main utility, sized with the column. Where solvent and water separate into layers, a decanter splits them after condensing. Because the solvents are flammable, the area around vents, sample points and pump seals is classified, tank filling is made static-safe and vents discharge upward or clear of adjacent walls and eaves.

Indicative Capacity Range

  • 50–3,000 litres feed/hour

Key Specification Inputs

VLE data, purity specification, reflux, pressure and condenser duty.

Technical Specifications

TechnologyBatch or continuous fractional distillation (rectification) of liquid solvent mixtures
Working PrincipleRepeated vapour-liquid contact in a column with reflux, separating components by boiling point
FeedMixed or contaminated solvent streams, filtered or settled before the still
Column InternalsStructured or random packing, or trays, chosen by feed solids, pressure drop and the separation needed
Operating PressureAtmospheric or reduced, set by boiling points and the heat sensitivity of the feed
Reflux ControlAdjustable reflux ratio, set by the purity wanted on each fraction
Heat SourceSteam, thermal oil or electric heating, chosen by what the site has
Condenser and CoolingWater-cooled, air-cooled or chilled, chosen by solvent volatility and local climate
Contact MaterialStainless steel, or another grade suited to the solvent mixture
Safety DesignClassified-area layout, earthing and bonding, static-safe tank filling, vents clear of walls
AutomationPLC control of temperatures, pressure, reflux and cut collection

Typical Process Route

1

Feed segregation and analysis

Mixed solvents are collected by type and sampled for composition, water and dissolved solids. The analysis feeds the column design, since the boiling points of the solvent and its contaminants decide how hard the separation is.

2

Filtration

Solids and colour bodies are filtered out before the still, because deposits on heating surfaces and column packing cut performance and force shutdowns.

3

Staged evaporation

The feed is heated in the reboiler by steam, thermal oil or electricity, at atmospheric or reduced pressure. Heating is held steady, since surges carry liquid up the column.

4

Rectification in the column

Vapour and returning reflux liquid meet on packing or trays, which enriches the light fraction at the top. Reflux ratio, column pressure and temperatures are controlled to hold each cut at its specification.

5

Condensation

Overhead vapour is condensed in a water, air or chilled condenser, which takes most of the heat load. A cooling shortfall shows up as uncondensed solvent vapour at the vent.

6

Oil-water separation

Where the condensate separates into layers, a decanter splits solvent from water or oil before storage. Water that stays dissolved in the solvent is left for the column to handle.

7

Cut collection and storage

Fractions go to separate receivers by boiling range, and off-specification cuts are held for another pass. Storage tanks fill in a way that stops static charge building up, and their vents are placed to disperse vapour safely.

8

Residue handling

The heavy bottoms leave the still as a thick or pasty residue, so the discharge route and any need for vacuum are fixed in design. The residue is cooled before it is drained.

Process & Equipment Modules

  • Feed tank with segregation by solvent type
  • Filter or strainer
  • Still with reboiler
  • Column with packing or trays
  • Reflux divider and reflux drum
  • Overhead condenser
  • Product cooler
  • Oil-water separator
  • Receivers for each fraction
  • Vacuum system
  • Recovered solvent storage with vent and static-safe fill
  • Flame-proof electrics, instruments and PLC

Plant Output

Separate solvent fractions, each at its own specificationPolished solvent ready for reuseSeparated water or oil layerPasty bottoms residue

Applications

  • Separating ethanol from water in botanical extraction streams
  • Splitting mixed solvent drums into separate usable solvents
  • Polishing ethanol, acetone or hexane to a tighter purity before reuse
  • Cutting a light head fraction and a heavy tail from solvent lots
  • Splitting solvent and water layers in condensate from extract lines
  • Pilot fractionation trials on a new solvent mixture
  • Purifying solvent for nutraceutical and fine-chemical process lines

Key Features

  • Column Matched to the Separation

    Column height, internals and reflux are fitted to how close the boiling points are, not taken from a stock size.

  • Controllable Reflux

    An adjustable reflux divider lets operators trade purity against energy and throughput on a given feed.

  • Condenser Sized as a Main Utility

    The condenser and cooling supply are sized with the column, since they remove most of the heat that goes in.

  • Static-Safe Storage

    Receivers fill through a pipe arranged to limit static charge, with vents that discharge upward and clear of walls and eaves.

  • Flammable-Duty Layout

    The still, vents, sample points and pump seals are placed and wired with the classified area in mind, and ignition sources are kept out.

  • Vacuum Option

    Reduced pressure lowers boiling temperatures where the feed is heat-sensitive or the solvent boils high.

Country Pages for Solvent Distillation Systems

This product is listed on the pages of the countries below, each with its own enquiry route. Where Kadali has no office in a country, enquiries are handled from the Accra office.

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Frequently Asked Questions

What information is needed to size Solvent Distillation Systems?
Every component in the feed with its boiling point, the vapour-liquid equilibrium data for the mixture, and the purity wanted on each fraction. Add the feed rate and the hours it runs, whether the feed carries solids, colour or water, the operating pressure you prefer, the cooling water temperature and the hazardous-area arrangement on site. Without equilibrium data the column and the reflux cannot be fixed.
What capacity range does Solvent Distillation Systems cover?
The indicative capacity range is 50–3,000 litres feed/hour. It is stated on a feed basis per hour, so restate your own volume on that basis and say how many hours a day the plant will run.
Should the plant run in batches or continuously?
A batch column takes cuts one after another, so it suits several solvents, varied feed and modest volumes, and one plant can run different campaigns. A continuous column suits one steady separation at a higher feed rate and needs less operator time, but it is less flexible. Capacity is quoted per hour of feed, so say how many hours a day you expect to run and how often the feed changes.
What limits the purity of a fraction?
How far apart the boiling points are. Close boilers need more stages and more reflux, which costs energy and throughput. Some mixtures, ethanol and water among them, form an azeotrope, a point beyond which ordinary distillation does not go, so ask what purity is truly needed. Contamination in the feed also affects the cut, so the proposal should state the feed composition it assumes.
How much cooling does a distillation system need?
More than most buyers expect. Most of the heat put into the reboiler leaves at the condenser, so cooling water or air capacity has to match nearly the whole heating duty. Low-boiling solvents may need a chilled loop in a hot climate. Where water is scarce, compare air cooling with recirculating water, and ask what condenser duty and cooling flow each offer assumes.
How is flammable solvent storage laid out safely?
Treat ignition sources as a checklist: hot surfaces and heaters, pump and motor friction or sparks, static during transfers, and hot work near the plant. Storage fill pipes should be arranged to limit static charge, and tank vents should discharge upward or horizontally away from walls so vapour is not trapped under eaves. Classify the areas around vents, sample points and pump seals, and choose electrical items to match. Keep piping and instrument diagrams and relief design with the plant records.
What happens to the residue at the bottom of the still?
Where the feed carries extract, the solvent distils off under vacuum and leaves a pasty residue. State how the residue must be discharged, whether it needs heating to flow and whether vacuum is needed, as well as which solvents are to be separated. Filtering solids and colour from the feed first keeps heating surfaces clean and the residue easier to drain.
How does this differ from a solvent recovery plant?
The solvent recovery distillation plant handles one used solvent coming back from a process line. A distillation system is the choice when the feed is a mixture to be split into several fractions, or when a solvent must reach a tighter purity than a simple still gives. If your streams need only take-back, start with the recovery plant; if they need splitting, the column is the main item.
How do I request a proposal for Solvent Distillation Systems?
Use the Request a Quote page and describe your project. Provide the solvent or solvents, the feed composition, the purity of recovered solvent you need and the volume per day.

Enquire about Solvent Distillation Systems

Send your raw material, target product and capacity to Kadali Africa Ventures for a technical proposal.

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