GLYCOL PRE-DEHYDRATIONOF GASBEFORE A CONTACTOR

摘要

A patent pending means of pre-dehydrating gas before entry into a contactor has beendeveloped and field-tested that improves the performance of glycol dehydrationequipment. The system consists of a means of extracting glycol from a contactor after ithas already contacted gas and reintroducing it before the contactor to achieve anupstream contact with the gas stream. The overall flow scheme is one of bothcountercurrent flow and concurrent flow contact.This results in a partial dehydration of gas occurring before it enters the contactor. Theefficiency of the pre-contact averages about 91% of a theoretical stage. This enhancesthe overall efficiency of the contactor and moves any water based corrosion or scalebuild-up outside of the contactor. The pre-dehydration can be used for any glycoldehydration system but is particularly applicable for gas that contains hydrogen sulfideor high quantities of carbon dioxide.This paper discusses how a glycol contactor in high CO2 and H2S service has beensuccessfully installed and operated. The gas stream that is dehydrated contains about85% CO2 and about 1.8% H2S. The equipment has been in operation for more thantwo years. During that time no maintenance has been required on the pre-dehydrationequipment. Since operation commenced there has been no downtime associated withthe pre-dehydrator or the contactor. After one and one half years of operation thecontactor was opened and inspected. There was only minor scale build-up and nocorrosion even though the contactor is made of standard carbon steel construction.