A solvent recovery system is a process system that takes effluent and extracts useful solvents and raw materials back out of the process waste stream. They can reduce the demand for purchase of new solvents & process inputs by recovering chemicals that can be reused in production or to flush the system between runs. They can also help manufacturers meet regulatory requirements or process standards by cleaning waste streams before they are released from the plant.
The recovery of solvents from effluent can be achieved with a variety of technologies. A common recovery method is solvent distillation systems, but liquid-liquid extraction, absorption systems, film evaporation, crystallization, and membrane separation can also be used, depending on the application.
Benefits to solvent recovery include:
- Reducing raw material and solvent costs by allowing manufacturers to reuse recovered chemicals and reduce transport and disposal costs of chemicals
- Lower EPA reporting requirements and risk because less solvents and chemicals are disposed of
- Continued manufacturing efficiency through the use of recovered chemicals, which after recovery are as usable and effective as new chemicals
The following types of solutions can be successfully recovered:
- Non-azeotropic solutions
- Aqueous non-azeotropic solutions
- Heterogeneous azeotropic solutions
- Aqueous homogeneous azeotropic solutions
A wide variety of mixtures, including paint lacquers and thinners, alcohols, acetone, methanal and most solvents have a boiling point up to 300-375 degrees F. Higher boiling point solvents can be reclaimed economically and safely through the use of vacuums, which lowers the effective boiling point. For a longer list, visit our solvent recovery page or contact an engineer today to discuss EPIC taking turnkey responsibility for your solvent recovery system.
The cost will vary widely from hundreds of thousands to millions of dollars and depends on several factors. Each of these factors could have major effects on systems costs:
- How much solvent do you want to recover?
- What size of stream will the system need to handle?
- Are the chemicals dangerous?
- How harsh are your operating conditions?
There are smaller standard solvent recovery units that can be purchased as-is, but for larger or more unique applications, a custom system design may be required. The cost of custom systems will mainly be determinate by how large and complicated the process design is. Increased process steps means more equipment, design work and fabrication time required.
Contact an engineer today to start discussing proven methods for your specific application and get a more precise number.
Most companies have reported recovery efficiencies of 75-80% but higher efficiencies are possible.
Several economic aspects need to be considered when selecting a solvent distillation system including: solvent usage, amount of waste solvent produced, cost of disposal of waste products, and capital and annual costs..
A basic example of a payback calculation can be found here.
For small, standard applications, EPIC can help you select an appropriate supplier of solvent recovery units, integrate the equipment into your existing operations, and add any process automation required to tie into your existing platforms. Commercially available batch units have capacities normally ranging from 5-280 gallons and take around 6-8 hours to process a batch. System setups include boiling chambers, condensers, and collection containers for reclaimed solvents.
For larger or more complicated systems, a full system design may be required. Most solvent recovery systems are distillation applications, and so the solvent recovery system design process follows a distillation design methodology. Typical solvent recovery systems heat and distill waste fluids to boil off the solvent, which is then collected as vapor and condensed (cooled) back down to liquid form for reuse.
Typical steps include:
- Identifying basic system requirements, such as flow rates, chemicals to be recovered, and other properties. A worksheet of this basic data can be found here
- Determining relative volatility of the key substances to be separated. The physical and chemical properties of the substances you are trying to separate are modeled using a mass and energy balance simulation program
- Once a suitable simulation is running, tradeoffs can be explored in simulation to come up with a final optimized version using key ratios and operating inputs
- Full system design is completed to include equipment lists, P&ID’s, automation design, and other design documentation
- Fabrication and controls engineering are completed on-site in our state-of-the-art fabrication plant. This allows for remote system fabrication that does not interfere with any existing operations or on-site civil modifications taking place at your facility
- Completed solvent recovery systems are fully tested before shipment, and arrive on-site ready for process hookups. Installation typically takes less than a week for modular systems, and on-site commissioning begins immediately
- Full system start-up is complete, and training is provided for system operators. EPIC will not leave until all punch-list items are checked off and you feel comfortable running and troubleshooting the system
Commercially available batch units have capacities normally ranging from 5-280 gallons and take around 6-8 hours to process a batch. System setups include boiling chambers, condensers, and collection containers for reclaimed solvents. We can help you select, integrate, or automate standard solvent recovery units.
If you need something larger, continuous solvent recovery, or have a-typical operating conditions, then you probably need a custom solvent recovery system. Please contact an engineer to discuss your specific application or custom system design.
Many solvent applications can recover original inputs to their full former purity by extracting them completely from the effluent stream. Recovering 75% of the input volume of a chemical solvent at full purity for reuse is a typical result of this type of system, and in these cases the recovered solvent should be as effective as a new solvent.
But not all solvents are recoverable to original state, depending upon how they were used and the relative boiling points of substances in the effluent stream. The composition of reclaimed solvent is very dependent on how well you can separate (and usually how close in boiling point) solvents and other chemicals are.
Keeping solvent wastes separated by their common constituents helps increase the likelihood of successful recovery, because trying to distill a mixed blend of several solvents often results in multiple solvents boiling off together or lingering in the bottoms.
Benefits of Solvent Recovery Equipment
What benefits does a solvent recovery system provide? This video from a solvent recovery equipment supplier does a good job of explaining them. The main benefits of being able to resuse solvents in-house include:
- Lowering your EPA reporting liability
- Reduce the cost and required volume of purchased solvents
- Lowering solvent removal and transport costs
- Minimizing legal exposure
Watch the video to understand how these benefits are achieved with no reduction in manufacturing efficiency: