The performance of natural gas dehydration using triethylene glycol (TEG) strongly depends on the purity levels of TEG in the regeneration unit. Coldfinger is a TEG regeneration technology reported to be capable of increasing TEG purity to levels above 99.8 wt.%, but conceptual models of this equipment appear to be lacking.
This work presents a methodology for modeling Coldfinger, where the equipment is represented as two theoretical equilibrium stages operating at different temperatures in the presence of internal vapor recirculation. The key parameters governing the functioning of the equipment are discussed on the basis of a series of simulations carried out for different top temperatures, internal recirculation ratios and stripping gas injection. The effect of the cooling efect of the Coldfinger is also analyzed through the quantification of the heat power exchanged by the system and its impact on the TEG purity levels achieved.
The conceptualization of the equipment functioning is first analyzed considering a simplified three-component system. Further analyses are performed by implementing the proposed Coldfinger modeling in the TEG regeneration stage of a gas dehydration unit where a multicomponent system is considered. The basis of comparison for quantification of the process efficiency is the behavior of a single-stage stripping process.
The results demonstrate that a regeneration of TEG up to approximately 99.9 wt.% is achievable by injecting smalls amounts of dry gas, considerably lower than conventional enhanced TEG regeneration by gas stripping.

Part of the work developed in this study was presented at the 14th International Congress on Chemical and Process Engineering held in Bologna, Italy, on May 26th to May 29th 2019 organized by the Italian Association of Chemical Engineering, AIDIC, and published in the journal Chemical Engineering Transactions.