The goal of this project is to test membranes for natural gas dehydration. The project is an experimental follow up of the modeling work in the sub-project “Membranes for gas dehydration”, where a closed loop process has been modelled to dehydrate natural gas using glycols as solvent, including a membrane contactor to absorb water into glycol from natural gas and a thermopervaporation unit for the glycol regeneration. 

Thermopervaporation for glycol dehydration is a novel method. In the thermovaporation unit, a liquid mixture of glycol and water at high temperatures (ranging from 30 to 90°C) flows through the upstream side of the membrane, where the water evaporates and passes through the membrane. The water vapor is then condensed in an air gap by contact with a cooling plate at a lower temperature similar to that of seawater (down to 4°C).

In this project a new test-setup and a thermopervaporation module for glycol regeneration has been designed and built in house. The performance of the thermopervaporation process depends on operating parameters, including temperature and composition of the feed, temperature of the cooling water, thermal resistance of the condensation plate and membrane, air gap thickness, flow rates of the feed and cooling water, and the geometry of the membrane module.

Compatibility of the membrane materials with glycol together with their long-term chemical and mechanical stability are of critical importance for subsea application. Membrane material should also be stable and compatible with all components available in natural gas at high pressure and operating temperature. In addition to compatibility and stability, a highly selective and permeable membrane is required in order to reduce the capital and operating costs.