We recover solvents from industrial emissions and return them to the production process. Through activated carbon adsorption and steam, nitrogen or nitrogen-plus-vacuum regeneration, the right technology depends on the solvent and the flow rate.
Recovery efficiency
Payback time
Emission profile
The principle is straightforward: solvent-laden air passes through an activated carbon bed that retains the solvent, while clean air returns to the atmosphere, enabling environmentally friendly, cost-effective recovery of solvents for continuous reuse.
We draw solvent-laden air (SLA) from the production machines, filter it, cool it, and feed it to the adsorbers filled with activated carbon. The carbon captures the solvent and clean air goes back to the atmosphere.
When the carbon reaches its maximum capacity, regeneration begins. We inertise the carbon with nitrogen to eliminate oxygen, then heat it to desorb the solvent. The circuit stays closed: zero emissions during this phase.
We condense the desorbed solvent at low temperature through a series of heat exchangers. In the X-CSR process, the vacuum further lowers the condensation temperature, cutting energy consumption by 40% compared to traditional systems.
The raw solvent goes to the distillation section (batch or multi-column) and, if needed, we dehydrate it using molecular sieves. The purified solvent returns directly to production in accordance with the reuse specifications.
All Donau Carbon Technologies technologies for solvent recovery are based on the same principle of adsorption on activated carbon. What changes is the regeneration method and, consequently, the cost profile, payback period and solvents compatibility.
Our patented technology combines hot nitrogen regeneration with vacuum extraction. Vacuum lowers the boiling point of the solvent in the carbon bed, reducing thermal consumption by 40% compared to conventional systems and bringing payback to under 3 years. Zero CO₂ emissions. We also offer it with electric heating instead of a thermal-oil boiler, making it a fully carbon-free plant.
The compact, pre-assembled version of the X-CSR design for flexographic printers and small converters. Same nitrogen-plus-vacuum regeneration technology, reduced footprint, no civil works, just a concrete platform. We deliver it fully pre-assembled and workshop-tested, with a fast payback even at lower solvent volumes.
The traditional technology for solvents with low water solubility: toluene, hexane, heptane, and chlorinated hydrocarbons. The saturated carbon is regenerated with steam, the steam-solvent mixture is condensed and the solvent is separated from water by a decanter. Technology developed under Lurgi Aktivkohle licence since 1981, with plants up to 560,000 Nm³/h installed worldwide.
Recovered solvent is returned directly to the production process. We don't destroy it, we don't dispose of it, we reuse it. Every ton recovered is a ton of virgin solvent that stays off the purchase order.
Unlike thermal oxidation, solvent recovery burns nothing. In the X-CSR version with electric heating, the plant produces zero CO₂ emissions, neither direct nor indirect from combustion gas.
Recovered solvent has direct economic value. In the real cases in our reference list, payback is typically between 1.5 and 3 years, starting from 300 t/year of treated solvent, after which the plant generates net revenue.
Our solvent recovery technologies comply with the Best Available Techniques defined by the IED Directive for the flexible packaging, printing and chemical industries. Compliance is built into the design, not added on top.
Solvent recovery is applicable in all industrial processes that use organic solvents in significant quantities and with sufficiently stable composition.
Ethyl acetate, alcohols, MEK and toluene from flexographic and rotogravure lines. The sector with the highest number of references in our reference list.
BTX, cumene, benzene and chlorinated hydrocarbons. ATEX-certified plants for classified environments, including revamping of existing installations.
Acetone, IPA and ethyl acetate to GMP-compliant purity. IQ/OQ documentation and full traceability for audits.
Toluene, hexane, heptane and plasticisers. SRS technology with Lurgi Aktivkohle licence, the sector standard since 1981.
The choice depends on three variables: solvent type, annual volume, and airflow rate. For hydrophilic solvents (ethyl acetate, alcohols, IPA) with flow rates from 60,000 to 130,000 m³/h, the X-CSR with Nitrogen regeneration is the optimal solution. For flow rates below 60,000 m³/h, the CX-CSR offers the same advantages in a compact format. For solvents with low water solubility (toluene, hexane, heptane), steam regeneration (SRU) is the established technology.
Based on Donau Carbon Technologies technical documentation, solvent recovery becomes economically viable starting from approximately 300 t/year. At 500 t/year, the typical payback with X-CSR is under 3 years. Below this threshold, thermal oxidation with an RTO is generally the most appropriate solution.
For solvent primarily ethyl acetate at 3–4 g/Nm³ concentration: electrical energy 1.07 kWh/kg, thermal energy 2.32 kWh/kg, nitrogen 0.2 Nm³/kg. The indicative total operating cost is approximately €0.25/kg of recovered solvent. The savings from purchasing virgin solvent determine the payback.
Yes. The modular design of the X-CSR and CX-CSR allows adsorption skids to be added at any time, expanding capacity without modifying the existing structure. Expansion is planned to coincide with already-scheduled production shutdowns.
During the adsorption phase, air leaving the adsorber contains solvent concentrations below IED limits. During the regeneration phase, the circuit is completely closed in nitrogen, with zero VOC emissions. In the electric heating version (Carbon-free), the plant produces zero CO₂ emissions
Have an emissions problem to solve or a plant to upgrade? Write to us: we will connect you with the right technical contact.
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