Process Control in the Regeneration of Monoethylene Glycol

A natural gas exploration company in Egypt extracts gas offshore, which is then piped onshore where it is prepared for transportation and further processing.

As the natural is extracted from the wellhead, it expands and thus its temperature strongly drops. In order to prevent the formation of ice and avoid frozen fittings, it must be heated.

For this purpose, an 80% monoethylene glycol mixture (MEG) is warmed up to 140 °C onshore and then pumped out to the gas extraction fields offshore. Here it is mixed into the extracted gas streams to elevate the temperature and to simultanously dehydrate the gas.

The MEG and the natural gas are then piped back, as a mixture, towards the mainland. Onshore, the MEG is regenerated and stored in a reservoir tank. It is then ready to be fed back into the cycle.

In order to properly control the regeneration process, the MEG concentration has to be determined in realtime. The measurement of the monoethylene glycol-water mixture takes place after the MEG has passed the evaporator.

To determine the exact concentration of the MEG, a PIOX R Processrefractometer is used. Because of the potentialy hazaradous area the PIOX is used in, it is enclosed in an explosion and flame proof Ex d enclosure and is ATEX Zone 1 certified.

Advantages of PIOX R concentration measurement:

• Determination of the MEG concentration in realtime (ATEX Zone 1)
• Drift-free, relaible and precise measurement
• Only minimal maintenance efforts necessary