The process, developed and patented by Siirtec Nigi, is used to dehydrate natural gas to very low dew points by glycol absorption, without using vacuum regeneration, no solvents and no consumption of stripping gas.
DRIGAS™ process recycles the glycol regenerator's overhead vapours, cooled and dried, to the stripping tower.
The vent gas off of a conventional regenerator with a stripping tower is cooled in an overhead condenser (1) and condensed water is separated in the overhead knockout drum (2). The wet gas coming from (2) is reused as stripping gas, feeding it to the bottom of the stripping tower by means of blower (3).
Spent glycol is used to dry the re-circulated gas to the stripping tower by means of a random packed atmospheric absorber (4) and a glycol pump (5) to move rich glycol from the bottom of the atmospheric absorber to the still tower.
If higher concentrations are required, a second stage of absorption (6) can be incorporated into the same atmospheric column fed by a small fraction of the regenerated, lean TEG. This arrangement gives TEG purity up to 99.99 wt%.
Main advantages of DRIGAS™ process are:
- Very low dew points
- Stripping gas is not required
- Low operating cost
- Low pollution
Glycol flowrates up to 1,000 m3/d, with TEG purity up to 99.99 wt%. Gas flowrates up to 15 million SCMD for each train, wet gas temperature up to 60°C and pressure up to 150 bar.