Continuous Solvent Recovery and Purification System

Start with your task

Plan the distillation trainDewatering, evaporation, rectification. Choose the separation routeDistillation, membranes, heat integration.

Plan the distillation train: dewatering, solvent evaporation and product rectification

A continuous recovery system splits the job into stages. Sichuan Forever describes its stripping-liquid solvent recovery process in three steps: primary distillation to remove water from the raw material; secondary distillation to evaporate the recoverable solvent completely into vapour and separate the residue; and tertiary distillation, the product distillation, aimed at improving the colour and purity of the product. [1]

Forever lists its automated SRS/PRS waste stripping liquid regeneration system at 600 L/h, with a delivery time of 3–4 months and a supply ability of 20 sets per year, and names LCD panel stripping liquid regeneration, isopropanol aqueous solution distillation and methanol aqueous solution distillation among its process packages. [2] Editorial calculation: 600 L/h over a 24-hour day is 14,400 L of feed per day.

The iScience review by Aboagye and co-authors (2021) states that distillation separates components "at a wide range of flow rates, regardless of the initial concentration, and with high purity", and that fractional distillation is used to separate multiple volatile components where azeotropes are not present. [3]

Give the supplier a full analysis of the spent solvent (components, water, dissolved solids, polymers, photoresist or other residues), the flow in L/h or kg/h, the purity and water limit the recovered solvent must meet, and the utilities available (steam or thermal oil, cooling water, vacuum).

Choose the separation route: plain distillation, membranes, extraction or heat integration

Azeotropes and water change the route. A 2023 Ind. Eng. Chem. Res. paper describing a solvent recovery design tool modelled a 1,000 kg/h stream of 51% isopropanol and 49% water with targets of at least 99.5% IPA purity and 99.0% water recovery; the optimized pathway was a pervaporation route (BYP1-BYP2-PVP2-PVP3, where PVP is pervaporation and BYP is bypass), costing $323,000 per year against an estimated $8.1 million per year for incineration. [4]

The same case returned 460.28 kg/h of isopropanol at 99.7% purity and 90.3% recovery, with 488.78 kg/h of water at 91% purity in the disposable stream. [4] Editorial calculation: 460.28 ÷ 510 kg/h of IPA fed = 90.3% recovery, matching the paper; the remaining 49.73 kg/h of IPA leaves with the water.

For energy, the iScience review reports that retrofitting an existing distillation column with a dividing wall can reduce operation and capital cost by up to 20–50%, and that Chaniago et al. (2015), recovering a semiconductor waste solvent mixture containing photoresist, observed about 40% energy savings by thermally coupling the columns in sequence and adding a heat pump. [3]

Sulzer lists pressure swing distillation, membrane separation and extractive or entrainer distillation for azeotropes; vacuum distillation, liquid-liquid extraction and fractional crystallization for heat-sensitive chemicals; heat integration; and skid-mounted units to limit downtime. [5]

Three-stage trains, heat-pump coupling, dividing-wall columns and pervaporation hybrids

The configuration follows from the stream; ask the supplier which one it proposes and why.

Configuration	What the source states	When to ask for it
Three-stage distillation train	Dewatering, solvent evaporation with residue separation, product distillation for colour and purity. [1]	Wet streams with dissolved residue, e.g. stripping liquids.
Thermally coupled columns with heat pump	About 40% energy savings in a semiconductor waste-solvent study. [3]	Large continuous flows with high reboiler duty.
Dividing-wall column	Retrofit can cut operation and capital cost by up to 20–50%. [3]	Multi-component separations in one shell.
Pervaporation hybrid	IPA–water case: 99.7% IPA at 90.3% recovery. [4]	Azeotropic aqueous solvents.
Pressure swing or extractive distillation	Listed by Sulzer for azeotropes. [5]	Azeotropes where membranes do not fit.

Dewatering column, evaporator and rectification column in a solvent recovery train

Module	Role	Fix in the order
Feed tank and pumps	Supply spent solvent at a steady rate. [2]	Flow in L/h; materials.
Dewatering column	Removes water from the raw material. [1]	Water limit after this stage.
Evaporator or stripping stage	Evaporates recoverable solvent and separates residue. [1]	Residue handling.
Product rectification column	Improves colour and purity. [1]	Purity, colour and water specification.
Membrane or extraction step (option)	Breaks azeotropes or removes impurities. [4] [5]	Membrane type; extraction solvent.
Heat integration (option)	Heat pump or thermally coupled columns. [3] [5]	Energy balance.
Automatic control	Runs the skid with automatic control. [2]	PLC, instruments, interlocks.

Throughput, heating duty, pressure and recovery rate the recovery plant is quoted on

Field	What it means and published values	Ask the supplier for
Processing Capacity (L/h)	Example: 600 L/h (Forever SRS/PRS). [2] Case study: 1,000 kg/h feed. [4]	Capacity at your composition.
Heating Power (kW)	Reboiler and evaporator duty; heat pumps cut it in one study by about 40%. [3]	Duty in kW; steam or oil use.
Operating Pressure (bar)	Atmospheric, vacuum or pressure swing, by stream. [5]	Column pressures.
Automation Level (%)	Automatic control on the Forever system. [2]	Control scope and interlocks.
Operating Temperature (°C)	Set by solvent boiling points and column pressure.	Temperatures per column.
Recovery Rate (%)	Case: 90.3% IPA recovery. [4]	Guaranteed recovery on your feed.
Purity (%)	Case: 99.7% IPA against a ≥99.5% target. [4]	Guaranteed purity, water and colour.
Power Supply (V AC)	Plant supply.	Voltage, phase, frequency.
Noise Level (dB(A))	Pumps, vacuum and heat-pump compressors.	Measured level.
Material	Wetted parts for the solvent.	Grades and gaskets.
Weight (kg)	Skid weight.	Operating weight.
Footprint (m²)	Skid size; Sulzer offers designs for limited space. [5]	Layout and height.
Ingress Protection	Electrical enclosures in solvent areas.	IP and hazardous-area rating.

Send the stream analysis, targets and utilities together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Spent solvent: [components; water; solids; residues]
Flow: [L/h or kg/h; hours per year]
Targets: [purity; water limit; colour; recovery]
Route: [distillation only or hybrid allowed]
Utilities: [steam or thermal oil; cooling water; vacuum; power]
Area: [hazardous-area classification]
Evidence: [pilot or test-centre results]

See manufacturer records Send an enquiry through CNFX

Buyer questions

How pure can recovered isopropanol be?

In a 2023 Ind. Eng. Chem. Res. case study, a 51% IPA–49% water stream was recovered to 99.7% IPA at 90.3% recovery using a pervaporation route. [4]

What stages does a continuous solvent recovery system use?

Forever describes primary distillation to remove water, secondary distillation to evaporate the solvent and separate residue, and tertiary product distillation for colour and purity. [1]

Can heat integration reduce energy use?

The iScience review cites about 40% energy savings from thermally coupled columns with a heat pump, and up to 20–50% lower operation and capital cost from dividing-wall retrofits. [3]

Sources and what still needs a direct check

Sources checked 2026-10-12. Forever and Sulzer describe their own systems; the iScience review and the Ind. Eng. Chem. Res. paper are peer-reviewed studies, and the latter's figures are a modelled case, not a plant guarantee.

Still to check yourself

Send a full analysis of the spent solvent.
Confirm whether azeotropes need a membrane, extraction or pressure-swing step.
Obtain guaranteed purity and recovery on your feed.
Obtain the energy balance and utility list.
Verify the legal supplier and factory.

Continuous solvent recovery and purification system (column-based distillation skid)