Cryogenic Condensation for Solvent Recovery & Abatement

Cryogenic Solvent Recovery separates condensable vapours from an effluent vent stream coming from production process equipment in order to reduce pollution and recover the solvents for reuse or disposal.

Safer, flexible, and economical, this is ideal for high-solvent concentration in vent gases, especially where liquid nitrogen is available as a utility. Adsorption or carbon beds are difficult to handle safely with high solvent concentrations. Cryogenic condensation is safer than thermal oxidizers and is non-destructive, which means high-value product in the chemical, pharma, and petrochemical industries can be recovered.

Cryogenic condensation is a reliable solution for treating vent gases with Volatile Organic Compounds (VOC) or Hazardous Air Pollutants (HAP). Cryogenic Solvent Recovery and Adsorption with Dry Regeneration can work together. If the gas flow rate is too large for only cryogenic solvent recovery, then adsorption can be used. When an adsorption abatement system is used, the media must be regenerated after a period of time. That regeneration step can be via cryogenic recovery which allows for dry regeneration.

Process Description

The separation process by condensation and partial solidification of VOCs is based on:

The decrease of the vapor pressure of the compounds at lower temperatures, in vapor/liquid and vapor/solid equilibrium
Using liquid nitrogen as the cooling fluid in a condenser
Emission limit levels (ppm) and/or yield of recovery (%) corresponds to the condenser outlet temperature
Control of the condenser outlet temperature is by automatic injection of liquid nitrogen in the condenser coils
The liquid nitrogen used in the system is not put in contact with the process circuit and is in a separate circuit under pressure, and therefore the nitrogen can be reused in gas form

Highlights

Proven solution for process emission streams containing VOCs or HAPs
Able to achieve VOC outlet concentration levels of only a few ppm, which is in compliance with the more restrictive local regulations
Creates a sustainable option to recover and reuse VOCs
No risk of the formation of dangerous toxins like dioxins, secondary pollutants, or greenhouse gases since there isn’t destructive combustion
The process strictly relies on phase changes (solid↔liquid, liquid↔gas) by decreasing vapor pressure to a low temperature and condenses/freezes the VOCs by cooling the stream with liquid nitrogen or another cryogenic fluid
The process is very safe as it does not involve sources of risk, like hot temperatures

Cryogenic Condensation: Typical Plant Configuration

Skid-mounted and supplied as a packaged unit
Specially designed cryogenic condensers with finned coils with flow conditioners
- Our patented technology for volatile compounds condensation is based on a special heat exchanger design, that is made of finned coils with flow conditioners. This particular system presents the following benefits:
  - Large surface area which allows for a fast response for peak variations of the flowrate
  - Very good resistance to thermal stress
  - Surface and volume margin for formation of low-density ice or organic solids
  - Easy handling of the recovered VOC, because the condensate is separated at a temperature close to the inlet
  - High efficiency and reduced nitrogen consumption, thanks to an advanced arrangement of economizers

Single or dual line for regeneration
Requires a small footprint
Layout can be adapted to each customer’s needs in order to fit the allocated space at the production site
Plant can be used in combination with carbon adsorbers, resin adsorbers, or scrubbers for applications that require pre-treatment
The control system is based on a PLC
The plant is completely automated; only start/stop commands are required for normal operation
Reliable operation with complex control logic, thanks to reliable control algorithms based on the experience of more than 300 applications in this field

Advantages of Cryogenic Condensation

Companies often struggle to find the right balance between investment, operating cost, and system reliability. Cryogenic Condensation is a reliable solution for VOC or HAP treatment, combining environmental sustainability and total cost of investment.

Low OPEX Cost: Liquid nitrogen is generally used as a cooling source for pollutant condensation. Since it is circulated in a dedicated circuit and it is never in contact with the effluent, the nitrogen is not contaminated and can easily be reused in gaseous form inside the factory network.
Safe: With Cryogenic Condensation, safety is not an issue. The units do not present a fire risk, even in the presence of highly flammable compounds in the effluent or in the environment, since no ignition source is introduced in the process. Thanks to this feature, units are suitable for installation inside ATEX classified areas without impacting the project.
Flexible Solution: The plant is highly adaptable and can handle various stream flowrates and VOC concentrations. The unit can work in a wide range of operating scenarios with minimum impact on normal operating costs. The automatic control system allows the plant to easily adapt to new working conditions.
Value Added: As a recuperative technology, solvents in liquid form are collected in a dedicated tank, thus allowing an easy reuse in plant processes. In the event that reuse is not an option, solvents can easily be collected as waste without generating any additional by-product or creating wastewater.
Eliminates Secondary Emissions: No secondary emissions (CO, CO2, NOx, etc.), which may require additional purification, are created in the process. The technology is based solely on the condensation of the pollutants. This saves time and money while producing superior results that are also better for the environment.