Solvent Recovery Unit | Activated Carbon Nitrogen Regeneration (TSA) • DEC.SRU_RSG™
DEC.SRU_RSG™ is an advanced activated-carbon adsorption system with inert-gas (nitrogen) desorption, used to capture and reclaim volatile organic compounds (VOCs) and industrial solvents — such as ethyl acetate and ethanol — from industrial exhaust air. It combines activated carbon adsorption with inert gas desorption to reclaim VOCs with high efficiency, while DEC.ULP™ Ultra-Loop™ energy recovery can further reduce thermal and cooling energy demand and associated emissions. This patented process helps operators cut VOC emissions and recover valuable solvents while complying with the latest environmental regulations and directives, and is widely used across packaging, chemicals, pharmaceuticals, and coatings industries.
recovery efficiency
RRE
(Recovery and Removal Efficiency)
reduction in SRU heat balance (DEC.ULP™)
reduction for heat dissipation and solvent condensation
(DEC.ULP™)
life-cycle carbon-footprint reduction
vs. solvent oxidation / atmospheric release
with low-carbon electricity
proven in industrial operation
(ISO 16290:2013)
DEC.SRU_RSG™ Quick Facts
- Technology
- Activated carbon adsorption + inert gas (nitrogen) TSA desorption, with integrated DEC.ULP™ Ultra-Loop™ energy recovery
- Recovery efficiency
- >99% VOC / solvent recovery
- Thermal energy
- Up to 53% reduction in SRU thermal heat balance (DEC.ULP™)
- Cooling energy
- Up to 55% reduction in cooling energy (DEC.ULP™)
- CO₂e reduction
- Up to approximately 99.6% lower life-cycle CO₂e footprint in the stated performance case, with low-carbon electricity, compared with solvent oxidation or atmospheric release
- Recovered solvent purity
- Typically below 1% water content (anhydrous, direct recovery), and below 0,1% adding optional DEC.ADM™ dehydration modules
- Water discharge
- Zero process wastewater
- Typical airflow range
- 5.000 – 1.000.000 Nm³/h
- Technology Readiness Level
- TRL 9 — proven in industrial operation (ISO 16290:2013)
Solvent Recovery Units, based on activated carbon adsorption, hot inert gas (N2, Nitrogen) regenerated, are using a core technology which has been proven in thousands industrial applications, treating variable volumes of gaseous effluent (typically 5.000 ÷ 1.000.000 Nm³⁄h); the regeneration of the adsorption media (activated carbon) is using Nitrogen as desorption media [DEC.SRU_RSG™ process, alternating different phases, as adsorption and TSA (thermal swing) regeneration, with N2, Nitrogen desorption], making this process well suited to variable SLA volumes and variable (low-medium-high) concentrated VOC streams (mono and multi-solvent). The regeneration nitrogen can be sourced on-site via an on-site nitrogen generator (DEC.N2G™) or via bulk liquid nitrogen supply (DEC.N2L™), depending on site consumption and logistics.
Back in 1980s, DEC developed the revolutionary steamless technology (DEC.SRU_RSF™) for regenerating the adsorbent, using an inert gas. Today, this legacy lives-on in the powerful, versatile high performance DEC.SRU_RSG™. With hundreds of successful applications across diverse industries and continents, DEC.SRU_RSG™ tackles both mono-solvent and multi-solvent systems, delivering direct recovery of anhydrous solvents with zero process water discharge.
For different process conditions, and/or type of solvents, and/or SLA flowrates, please check the available solvent recovery processes.
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Why Use Nitrogen Regeneration for Solvent Recovery?
Azeotropes, where solvents and water mix inextricably (binary and ternary - e.g. acetates and alcohols ), often pose a recovery challenge: DEC.SRU_RSG™ steps in as a game-changer, allowing the direct recovery with a no compromise purity. With its ability to tackle azeotropes and various miscibility challenges, DEC.SRU_RSG™ redefines solvent recovery allowing the application of this sustainable solution to a wide range of industrial applications.
The DEC.SRU_RSG™ process also represents the solution for the recovery of problematic solvents (due to their volatility, flammability, or reactivity), which are deemed "NOT RECOVERABLE" or "DANGEROUS": DEC.SRU_RSG™ can handle solvents that other conventional methods might struggle with, expanding your recovery options. Typical application, is the recovery process of ketones (such as MEK - methylethylketone): check for our DEC.FPS™ process control modules.
SRUs (Solvent Recovery Units) that utilize a nitrogen-regenerated TSA (Temperature Swing Adsorption) cycle are highly regarded for their robust design and sustained performance. This regeneration method contributes significantly to their durability and extended operational lifespan, making them a reliable choice for long-term solvent recovery applications. Their ability to consistently perform over prolonged periods minimizes downtime and reduces overall maintenance requirements.
The Technology Readiness Level (TRL) of DEC SRUs equipped with DEC.SRU_RSG™ process reached a high level of maturity, classified nowadays as TRL 9 (actual system proven in operational environment, according to ISO 16290:2013): the DEC.SRU™ technology is commercially available and has been proven to work effectively in real-world applications.
What Is DEC.SRU_RSG™?
A Solvent Recovery Unit (SRU | SRP | SRS) consists of a specifically designed DEC.SBC™ static concentrator, coupled with an “in-situ” regeneration process.
A static concentrator employs an adsorbent to adsorb contaminants (VOCs, solvents) from a gas (SLA, solvent-laden air): selected adsorbent shall be a highly porous material with a large surface area, which makes it an effective adsorbent (typically DEC.ACA™ • activated carbon). The adsorbent is packed into a series of adsorbers, and the gas stream is passed through the adsorbers in sequence. As the stream passes through each adsorber, contaminants are adsorbed onto the adsorbent. Once an adsorber is saturated with contaminants, it is taken offline and regenerated. Regeneration involves both mechanical and thermal energy to be delivered to the adsorbent: these combined energies will drive off the adsorbed contaminants (known as desorption). These contaminants are then driven through a condenser (heat exchanger), for direct condensation and reuse. Once desorption cycle is completed, the adsorbent will be ready for the next adsorption cycle.
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How Does Nitrogen-Regenerated Solvent Recovery Work?
A Solvent Recovery Unit (SRU) is an industrial system designed to capture and reclaim solvents from vapor phase waste streams (SLA, Solvent Laden Air): its primary objectives are to minimize environmental impact, adhere to industrial emission regulations, promote a circular economy, contribute to DECarbonization, and generate substantial cost savings by reducing reliance on new solvent purchases, thereby lowering operational costs.
The fundamental principle governing solvent recovery units is adsorption, most commonly utilizing activated carbon. The typical process unfolds in several stages:
Why Nitrogen Regeneration Helps Protect Solvent Quality
DEC.SRU_RSG™'s "dry" Nitrogen-based desorption process ensures a negligible impact from hydrolysis reactions, safeguarding solvent integrity and purity for unprecedented recovery efficiency.
Direct Anhydrous Solvent Recovery
DEC.SRU_RSG™ units can be equipped with DEC's exclusive gas-phase pre-dehydration process, based on DEC's exclusive selective desorption algorithm (DEC.PHD™): this innovative process offers the advantage of directly recovering a mixture of solvents with an extremely low water content, without the drawbacks of condensing / freezing important quantities of water, delivering outstanding energetic advantages and avoiding waste-water (contaminated by solvents) disposal or additional treatment, minimizing operational and environmental impact.
For increased dehydration performances, additional modules are available [see dehydration modules (DEC.ADM™) and/or distillation systems (DEC.DST™)].
The Solvent Laden Air (SLA) stream processed by the SRU carries not only VOCs but also water vapor (humidity), typically ranging from 5 ÷ 18 g/m³ depending on season and location. Partial adsorption of humidity on the activated carbon, can affect the purity of the recovered solvent: DEC.RHC™ modules address this challenge by reducing the impact of humidity and optimizing energy consumption.
DEC.SRU_RSG™ Recovery Efficiency
Not only does DEC.SRU_RSG™ offer exceptional solvent recovery rates (ultra-low TVOC stack emissions), but it also stands as a beacon of sustainability. Its innovative design achieves the lowest emission values in the industry, ensuring minimal environmental impact, and compliance with any global VOC emission standards. This means you can protect the planet, while maximizing your solvent recovery, achieving a recovery yield of up to 99% or more.
- Reduced air pollution: minimized emissions contribute to cleaner air quality and a healthier environment.
- Enhanced compliance: Meet stringent environmental regulations with confidence, demonstrating your commitment to sustainability.
- Optimized resource use: Recover more solvents, reducing waste and conserving valuable resources.
DEC.SRU_RSG™ Energy Efficiency
Efficient DEC.ERS™ (Energy Recovery Systems) are available, to lower operating costs (OPEX): check DEC.ULP™ (Ultra-Loop) modules, for more details.
DEC.SRU_RSG™ can be integrated with DEC.ULP™ (Ultra-Loop) energy-recovery modules to reduce the energy required across the solvent recovery cycle. In the performance case represented on this page, the integrated solution delivers up to 53% reduction in SRU thermal heat balance and up to 55% reduction in cooling energy for heat dissipation and solvent condensation.
DEC.SRU_RSG™ Solvent Recovery and Life-Cycle CO₂e Footprint
DEC.SRU_RSG™ transforms solvent treatment from an emission-control process into a resource-recovery strategy. By recovering solvent for reuse rather than exhausting it to the atmosphere or destroying it through thermal oxidation, the system can avoid the upstream carbon footprint associated with replacement solvent while also preventing the carbon contained in the recovered solvent from being released through oxidation. Where recovered solvent displaces virgin solvent, the resulting life-cycle carbon footprint is therefore driven primarily by the energy required for recovery, with further reductions achievable through electrification powered by low-carbon electricity. In this way, DEC.SRU_RSG™ combines solvent recovery, VOC emission prevention and energy transition to deliver a substantially lower life-cycle CO₂e footprint than conventional solvent disposal or oxidation routes.
DEC.SRU_RSG™ System Simplicity and Reliability
While DEC.SRU_RSG™ solvent recovery units boast advanced technology and impressive capabilities, their operation and maintenance remain surprisingly straightforward. You don't need a team of dedicated specialists to harness its power. DEC SERVICE remotely monitors your SRU, ensuring optimal performance and freeing your resources for other priorities. This seamless remote support (DEC.HDS™) allows you to run the SRU efficiently with minimal operator involvement. It's a testament to DEC's commitment to making cutting-edge technology accessible and user-friendly, letting you focus on what matters most while your SRU quietly delivers exceptional performances.
DEC.SRU_RSG™ System Configurations
DEC Solvent Recovery Units (SRUs) are available in both skid modular layout (DEC-SMS™ • Smart Modular Systems, pre-built and pre-tested at our workshops) or in full customizable version (DEC-CBS™ • Custom Built Systems, with on-site erection). A fully electric variant of the DEC-SMS™ modular platform is also available, for sites looking to minimize direct fuel use.
DEC.SRU™ Regeneration Technology Comparison
| Technology | Regeneration media | Recovered solvent | Best suited for |
|---|---|---|---|
| DEC.SRU_RSG™ (this page) | Hot inert nitrogen (TSA) | Direct, anhydrous — typically <1% water | Azeotropic mixtures; reactive or flammable solvents (e.g. ketones); zero wastewater |
| DEC.SRU_RSV™ | Steam (TSA) | Wet — requires downstream separation/dehydration | Sites with low-cost steam already available on-site |
| DEC.SRU_RTV™ | Thermal + vacuum swing (T+VSA) | Direct, low water content | Heat-sensitive or high-boiling solvents |
| DEC.SRU_RSC™ | Direct condensation (no adsorption cycle) | Direct | High-concentration solvent streams |
Engineering and Project Consultation
If you are looking for a reliable and efficient solvent recovery unit, DEC.SRUs™ (Solvent Recovery Units) are the right and best option: DEC.SRUs™ are engineered for the specific process and recovery requirements, with processes, configurations and options to meet the needs of different applications, present and future challenges.
Contact DEC for a free consultation: we can help you assess your needs and recommend the best SRU for your operation.
DEC.SRU_RSG™ Key Takeaways
DEC.SRU_RSG™ is a patented solvent recovery process that combines activated carbon adsorption with inert gas (nitrogen) desorption and heat recovery to reclaim volatile organic compounds (VOCs) from industrial airstreams with high efficiency. The process routinely achieves recovery rates above 99%, while its dry, nitrogen-based regeneration cycle and DEC.ULP™ heat-recovery modules significantly reduce thermal and cooling energy demand and associated emissions.
Because the carbon bed is regenerated with hot inert nitrogen instead of steam, DEC.SRU_RSG™ delivers direct, anhydrous solvent recovery: recovered solvents typically come out at less than 1% water content, without condensing or freezing large volumes of process water and without the wastewater treatment, disposal, or hydrolysis risk associated with steam-regenerated systems. This makes DEC.SRU_RSG™ especially well suited to azeotropic mixtures and reactive or flammable solvents, such as ketones, that other recovery methods struggle to handle safely.
In short, a DEC.SRU_RSG™ Solvent Recovery Unit (SRU) is an energy-efficient plant system that optimizes activated carbon adsorption and desorption with inert gases to recover and reuse VOCs and industrial solvents, minimizing natural gas, electricity, and overall operating costs while supporting regulatory compliance and a circular economy approach to solvent use.
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Reach our Technical Sales & Applications engineering team to discuss your VOC & HAP emission control requirements
FAQs • Frequently Asked Questions
Solvent Recovery, Activated Carbon, Nitrogen Regenerated ♻️ DEC.SRU_RSG™ process
What is a solvent recovery unit (SRU)?
A solvent recovery unit (also known as Solvent Recovery Plant - SRP or Solvent Recovery System - SRS) is an industrial system designed to capture, recover, and reuse solvents from air emissions. It reduces VOC emissions, lowers operating costs, and improves environmental compliance.
How does activated carbon solvent recovery work?
Solvent-laden air (containing VOCs) is passed through a bed of activated carbon. Activated carbon adsorbs solvent vapors from process air, cleaning the exhaust air. Once saturated, the carbon is regenerated, releasing the solvent for recovery and reuse.
What is nitrogen regeneration in solvent recovery?
Nitrogen regeneration uses hot inert nitrogen gas to safely desorb solvents from activated carbon without oxygen, preventing fire and explosion risks.
What are the advantages of DEC.SRU_RSG™ over steam regeneration?
DEC.SRU_RSG™ eliminates wastewater, improves safety, recovers dry solvents, reduces energy consumption, and avoids solvent hydrolysis associated with steam systems.
What efficiency can be achieved with solvent recovery systems?
Advanced systems like DEC.SRU™ can achieve up to 99% solvent recovery efficiency with very low VOC emissions.
Which industries use solvent recovery systems?
Industries include pharmaceuticals, chemicals, printing, coatings, packaging, and petrochemicals where VOC emissions are present.
Can azeotropic solvents be recovered?
Yes, nitrogen-based systems allow recovery of azeotropic and difficult solvent mixtures without water contamination.
Why is solvent recovery environmentally beneficial?
Solvent recovery prevents VOCs from being exhausted or destroyed when the recovered solvent can be reused, reducing material loss and supporting circular resource use. It can also lower the life-cycle CO₂e footprint by avoiding replacement solvent and associated upstream emissions; the magnitude depends on the solvent, recovery yield and energy source.
How does DEC.ULP™ improve the energy performance of DEC.SRU_RSG™?
DEC.SRU_RSG™ can be integrated with DEC.ULP™ Ultra-Loop™ energy-recovery modules. In the performance case represented on this page, the integrated solution delivers up to 53% reduction in the SRU thermal heat balance and up to 55% reduction in cooling energy for heat dissipation and solvent condensation.
How does DEC.SRU_RSG™ reduce the life-cycle CO₂e footprint?
DEC.SRU_RSG™ recovers solvent for reuse instead of exhausting it to the atmosphere or destroying it through thermal oxidation. Where recovered solvent displaces virgin solvent, this avoids the associated upstream production and transport footprint and prevents the recovered solvent carbon from being released through oxidation. In the stated case-study basis, the no-treatment route is 5.02 kg CO₂e/kg solvent, while conventional hot-oil DEC.SRU™ operation is 0.86 kg CO₂e/kg solvent (about 83% lower). With fully electric operation using the stated low-carbon electricity factor, the footprint falls to 0.02 kg CO₂e/kg solvent, corresponding to approximately 99.6% lower life-cycle CO₂e than the no-treatment baseline. Actual results depend on solvent composition, recovery yield, energy source, operating conditions and system boundary.
What safety advantages does nitrogen provide?
Nitrogen creates an inert atmosphere, eliminating explosion risks when handling flammable solvents such as ketones.
What is the difference between TSA and VSA solvent recovery?
TSA uses temperature changes to regenerate adsorbents, while VSA uses pressure variation. TSA with nitrogen is preferred for high purity and safety.
Is DEC.SRU™ technology proven?
Yes, it has reached Technology Readiness Level 9, meaning it is fully proven in industrial environments worldwide.
Is pricing available for DEC.SRU_RSG™, and can I purchase a system directly?
DEC.SRU_RSG™ systems are custom-engineered, quote-based industrial equipment, so there is no fixed list price. Each system is sized and priced individually once DEC's engineering team has evaluated the customer's solvent, throughput, site utilities and target emission limit. Request a quote and DEC's Technical Sales & Applications engineering team will follow up with a proposal.
How does DEC.SRU_RSG™ compare to the other DEC.SRU™ regeneration technologies?
DEC.SRU_RSG™ is one of four DEC.SRU™ Solvent Recovery Unit regeneration technologies: nitrogen (DEC.SRU_RSG™, this page), steam (DEC.SRU_RSV™), vacuum (DEC.SRU_RTV™) and direct condensation (DEC.SRU_RSC™). See the SRU overview page for the full technology comparison and guidance on which fits a given solvent, humidity and safety profile.
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