Solvent Recovery Unit ♻️ activated carbon
Nitrogen regeneration (TSA) | DEC.RSG™ | DEC.SRU™
DEC.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 delivering massive cuts in utility consumption and emissions compared to conventional, steam-regenerated recovery plants. 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.
DEC.RSG™ at a glance
- Technology
- Activated carbon adsorption + inert gas (nitrogen) TSA desorption, with heat recovery
- Recovery efficiency
- Over 99% VOC/solvent recovery
- OPEX reduction
- Up to 46% lower operating expenses vs. conventional solvent recovery setups
- Recovered solvent purity
- Typically below 1% water content (anhydrous, direct recovery)
- Water discharge
- Zero process wastewater
- Typical airflow range
- 5.000 – 1.000.000 Nm³/h (Solvent Laden Air, SLA)
- 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.RSG™ process, alternating different phases, as adsorption and TSA (thermal swing) regeneration, with N2, Nitrogen desorption], determining this process to be the ideal choice and the top performer when dealing with variable SLA volumes and variable (low-medium-high) concentrated VOC streams (mono and multi-solvent).
Back in 1980s, DEC developed the revolutionary steamless technology (DEC.RSF™) for regenerating the adsorbent, using an inert gas. Today, this legacy lives-on in the powerful, versatile high performance DEC.RSG™. With hundreds of successful applications across diverse industries and continents, DEC.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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SRU RSG™ • challenging solvent recovery made possible
Azeotropes, where solvents and water mix inextricably (binary and ternary - e.g. acetates and alcohols ), often pose a recovery challenge: DEC.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.RSG™ redefines solvent recovery allowing the application of this sustainable solution to a wide range of industrial applications.
The DEC.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.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.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.
Solvent Recovery Unit (SRU RSG™) • concepts
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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the solvent recovery process (SRU RSG™) • how it works?
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:
- Filtration: initial removal of particulate matter from the SLA vapor stream to prevent fouling of subsequent equipment and ensure optimal performance of downstream processes.
- Cooling: reducing the temperature of the vapor stream to enhance the adsorption efficiency of the activated carbon; lower temperatures generally increase the adsorption capacity of the activated carbon towards solvent molecules, increasing efficiency.
- Adsorption: this is the core stage where solvent vapors are adsorbed onto the variable porous surface of activated carbon beds. As the contaminated air passes through the AC beds, solvent molecules are trapped while the purified air is released at the stack (FGS).
- Regeneration: after the adsorption beds become saturated with solvent, they need to be regenerated to release the adsorbed solvents and prepare the carbon for reuse. This is achieved by desorption, using a hot inert gas (Nitrogen) in a Temperature Swing Adsorption (TSA) cycle. The hot nitrogen causes the adsorbed solvents to desorb and detach from the carbon surface.
- Condensation: the regeneration gas, now rich in desorbed solvent vapors, is then cooled. This cooling causes the solvent vapors to condense back into liquid form, allowing them to be collected for reuse or further processing.
- Dehydration: solvents often contain a certain quantity of water, typically due to adsorbed humidity. A dehydration system, utilizing molecular sieves, is employed to remove this water from the recovered solvent mixture, ensuring the purity of the recovered solvent.
- Distillation: if the recovered solvent is a mixture of different solvents, or if further purification is required (to remove by-products), the solvent mix is then separated through distillation: this process leverages the different boiling points of the components to achieve separation, yielding pure solvents for direct reuse in your industrial applications.
solvent recovery (SRU RSG™) • hydrolysis minimized, recovery maximized
DEC.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 recovery of solvents
DEC.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.
solvent recovery (SRU RSG™) • best-in-class recovery efficiency
Not only does DEC.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.
solvent recovery (SRU RSG™) • best-in-class 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.RSG™ with DEC.ULP™ (Ultra-Loop) modules delivers unmatched operational and maintenance cost savings compared to any other technology on the market: up to a 30% reduction in O&M costs compared to traditional solvent recovery methods.
solvent recovery (SRU RSG™) • simplicity meets power: expert performance, without complexity
While DEC.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.
solvent recovery (SRU RSG™) • choose from our Smart Modular or Custom Built Systems
DEC Solvent Recovery Units (SRUs) are available in both skid modular layout (DEC.SRU_SMS™ • Smart Modular Systems, pre-built and pre-tested at our workshops) or in full customizable version (DEC.SRU_CBS™ • Custom Built Systems, with on-site erection).
get a free 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 the most advanced and reliable Solvent Recovery Units on the market, 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.
solvent recovery (SRU RSG™) • key takeaways
DEC.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 drastically cut utility consumption, reducing OPEX by up to 46% compared to conventional solvent recovery setups.
Because the carbon bed is regenerated with hot inert nitrogen instead of steam, DEC.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.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.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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FAQs • Frequently Asked Questions
♻️ 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.RSG™ over steam regeneration?
DEC.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.
Is solvent recovery environmentally beneficial?
Yes, it reduces VOC emissions, minimizes hazardous waste, lowers carbon footprint, and supports circular economy practices.
Does solvent recovery reduce operating costs?
Yes, recovered solvents can be reused, significantly reducing raw material costs and waste disposal expenses.
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.
