Cryogenic cooling, or cryo-condensation, could be the most cost-effective method for minimising volatile organic chemical (VOC) emissions from certain processes and conditions, says a new white paper from Linde LLC.

More specifically, VOC emissions in solvent and hydrocarbon storage tanks and manufacturing processes, when certain conditions exist, could be most cost-effectively minimised by cryo-condensation.

Cryo-condensation is a relatively simple process of using the cold from vaporizing nitrogen to condense organic compounds exiting through a vent or in a process gas stream.

The white paper was authored by Robert D’Orazio, Senior Engineer for Linde LLC, who points out that many chemical plants, oilseed processing plants, tank farms and terminals already have liquid nitrogen on-site which is vaporized to gaseous nitrogen for blanketing, purging, pressure transfer and other uses.

“The Linde VOC control system simply uses the cold from liquid nitrogen to control VOC emissions from storage tanks, then returns the nitrogen as a gas to the processes,” D’Orazio said. “The VOC control system is modular, so it is cost efficient and easy to implement.”

“The savings can be even greater when the system is used to recapture high-value products such as hexane from supply and vent lines.”

The white paper, titled Low-Cost Method for VOC Emission Control Utilising Cryogenic Condensation, provides details on the conditions and requirements that make cryo-condensation practice competitive compared with adsorption or thermal oxidation – and when it is not.

Conditions affecting the decision include concentration effects, blanketing and tank use patterns, fixed versus floating roof, and stored material considerations, such as single component versus mixtures, product value and potential re-use and compliance effects.