Treatment and recovery of Volatile organic compounds (VOCs) by cryocondensation
The technique of cryocondensation consists of cooling atmospheric emissions to very low temperatures by utilizing liquid nitrogen.
This technology is not only useful for the purification of VOC emissions, but also allows for the condensation and recovery of expensive raw materials and contaminants that are usually present in emissions of processes where organic solvents are involved.
Cryocondensation is a clean and non-destructive method because it recovers vapor emissions in liquid form that would otherwise be released into the atmosphere. This is accomplished by carrying out a controlled cooling of the process vapors of a determined substance to reach its dew point in the moment when it starts its condensation.
By use a of condensation column, the contaminated air current is crossed with VOCs, circulating liquid nitrogen in a countercurrent flow which cools the air with a volatile substance below the condensing temperature (reaching up to -200ºC). This produces the freezing of the moisture in the air and obtains a liquid product that can be reused in the process. The nitrogen used can be reutilized by a small compression station for use as gas in manufacturing or it can be discharged into the atmospheres if there is no use for it.
The range of available equipment covers a wide spectrum of recoverable solvents such as: toluene, acetone, methanol, chlorinated derivatives, hydrocarbons, etc.
Cryocondensation can treat different currents, flows, and pressures. Its systems can even be custom designed for each case. As mentioned before, there exists the possibility to refuse the condensed solvents as well as the nitrogen generated.
Thanks to its properties, liquid nitrogen is used as a refrigerating agent that allows for the condensation of all substances considered VOCs in a range between -30 and -120 ° C.
The condensing temperature is determined by the components to be treated and by the ppm that we wish to achieve in the emission current.