Monoethylene glycol reclamation (MEG reclamation) is an industrial process used to remove dissolved salts, corrosion products, hydrocarbons and degradation by-p
Monoethylene glycol reclamation (MEG reclamation) is an industrial process used to remove dissolved salts, corrosion products, hydrocarbons and degradation by-products from monoethylene glycol (MEG), allowing the glycol to be reused in hydrocarbon production systems. MEG is commonly used as a thermodynamic hydrate inhibitor in subsea pipeline systems, where it is injected into production fluids to prevent the formation of hydrates that could obstruct flowlines.
MEG reclamation is principally employed in offshore natural gas developments, long-distance subsea tie-backs, floating production storage and offloading facilities (FPSOs), and onshore gas-processing plants. The process is often integrated with MEG regeneration systems that remove water from the recovered glycol stream.
The use of MEG as a hydrate inhibitor became increasingly common with the development of deep-water oil and gas fields and long-distance subsea production systems. Unlike methanol, MEG can be recovered, purified and re-used, reducing chemical consumption and operating costs.
As production fluids travel through pipelines, the recovered MEG becomes contaminated with dissolved salts, corrosion products, hydrocarbons, production chemicals and degradation compounds. Without reclamation, these contaminants can accumulate and adversely affect process equipment and flow assurance performance.
Although the terms are sometimes used together, regeneration and reclamation describe different stages of MEG recovery.
MEG regeneration is the removal of water from recovered glycol streams. The process typically employs distillation to increase the MEG concentration to the level required for reinjection into production systems.
MEG reclamation is the removal of dissolved and suspended contaminants, including monovalent and divalent salts, corrosion products and degradation compounds. Reclamation is intended to maintain glycol quality and limit the accumulation of contaminants within the MEG circulation loop.
Many facilities incorporate both regeneration and reclamation processes within a single recovery system.
MEG reclamation systems are generally configured using either a full-stream or a slip-stream reclamation process.
In a full-stream system, the entire rich-MEG return stream is processed through the reclamation unit to remove salts and other non-volatile contaminants. Full-stream systems are frequently integrated with regeneration facilities to provide simultaneous water removal and salt removal.
In a slip-stream configuration, only a portion of the circulating MEG is treated for salt removal while the remainder undergoes conventional regeneration. The selection of reclamation philosophy depends primarily on anticipated formation-water production rates, salt loading, chemical management requirements and overall system economics.[1]
MEG reclamation systems generally employ combinations of:
Modern MEG reclamation systems commonly employ vacuum distillation to recover monoethylene glycol while avoiding thermal degradation. Operating under reduced pressure lowers the boiling temperature of the MEG-water mixture, allowing salts and other non-volatile contaminants to remain in the reclaimer while purified MEG is recovered and recycled.[2]
This includes decanter centrifuges,[4] gas-tight centrifuges, and basket centrifuges
The specific process arrangement varies according to contaminant loading, required glycol purity and the characteristics of the produced water.
Research into MEG reclamation systems has shown that control of dissolved oxygen is a critical aspect of process design. Oxygen ingress, particularly in high-temperature, salt-containing MEG environments, can promote localized corrosion of process equipment, including duplex stainless steels. Studies have found that corrosion is most likely to occur where salts are deposited, while minimizing oxygen ingress through system integrity measures, gas blanketing, and oxygen control practices can significantly reduce corrosion risk.[5]
A number of companies supply MEG regeneration and reclamation technologies for offshore and onshore hydrocarbon production facilities.
MEG processing and reclamation technologies have been implemented in a number of major onshore and offshore gas developments worldwide. Below is a list of units by Continent :
- Norway - Ormen Lange, Åsgard B,[10] Gjøa Field[11]
- UK - Britannia Satellites
- Laggan Tormore (Shetland Islands) [12]
- United States Gulf of Mexico - Shell Mensa WD-143 Offshore Project,[13] Independence Hub [14]
- Brazil - Mexilhão Platform (Petrobras - Santos Basin),[15] FPSO Cidade de Santos (Santos Basin)[16]
- Mozambique - Coral Sul FLNG / Coral North FLNG (Mozambique)[17]
- Saudi Arabia - Wasit Onshore Gas Plant[18]
- Egypt - West Nile Delta [19]
- Azerbaijan - Shah Deniz
- India - KG-D6
- China - Liwan Gas Field
- Australia - Prelude FLNG has a large MEG Reclamation Unit as referenced here.
Pluto-LNG
FPSO Ichthys Venturer [20]
- Otway Gas Plant (OGP) - Beach Energy [21]
New Zealand - Kupe
The use of MEG reclamation technology is particularly common in deep-water gas developments requiring long subsea tie-backs.
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