The glycol reboiler is the fired vessel in a TEG dehydration unit where the water absorbed from the gas is boiled back out of the glycol. If the contactor is where the glycol picks up water, the reboiler is where it gives it up again, restoring the glycol to a lean, water-hungry state so it can be reused. This guide focuses on that regeneration side of the unit - how the reboiler drives off water, the critical temperature window it must hold, and why lean glycol quality lives or dies here.
Glycol Reboiler in one line: A glycol reboiler is the heated vessel in a glycol dehydration unit that regenerates rich (water-laden) glycol by boiling the absorbed water out as vapor, which leaves through a still column. Restoring the glycol to a lean, high-purity state - by holding a temperature high enough to drive off water but below where TEG degrades - is what lets the glycol be recirculated to the contactor.
A glycol unit only works because the glycol is used over and over. In the contactor the glycol absorbs water and becomes rich glycol; if there were no way to get that water back out, the glycol would saturate and stop drying gas. The reboiler is what closes the loop. It heats the rich glycol until the water boils off as steam, leaving behind lean glycol that is dry enough to go back to the top of the contactor and start absorbing again.
This works because water boils at a much lower temperature than triethylene glycol. When the reboiler heats the mixture, the water flashes to vapor and escapes while the glycol stays liquid. The water vapor rises out through a still column, or stripping still, mounted on the reboiler and vents to atmosphere or a vapor recovery system, carrying the removed water away and taking some hydrocarbon vapors with it.
So the reboiler is the regeneration heart of the unit, the mirror image of the contactor. The contactor does absorption at high pressure and low temperature; the reboiler does desorption at low pressure and high temperature. Together they form a continuous cycle, and the reboiler is what makes that cycle sustainable rather than a one-time use of glycol.
Reboiler temperature is the single most important control point in glycol regeneration, and it lives inside a narrow window. It has to be hot enough to actually boil the water out - run it too cool and the glycol leaves only partly regenerated, so it returns to the contactor still carrying water and cannot dry the gas to spec. Under-heating quietly ruins the dehydration performance of the whole unit.
But it also has to stay below the point where triethylene glycol begins to thermally degrade, which for TEG is roughly 204 degrees C. Push past that and the glycol breaks down into acids and sludge, its purity and drying power fall, and it corrodes the system. So reboilers are typically held around 190 to 200 degrees C - hot enough to strip the water, cool enough to protect the glycol - and the achievable lean glycol purity, and thus the achievable gas dew point, depends directly on hitting this window.
The heat itself usually comes from a fired firetube burning fuel gas, though some units use hot oil or electric elements. Some reboilers add stripping gas or use a stripping column to reach an even higher lean glycol purity than boiling alone can achieve, which is needed when a very deep gas dew point is required. Either way, the reboiler temperature and the resulting lean glycol quality are the levers that set how dry the finished gas can be.
Reboilers suffer a recognizable set of problems. Salt and solids from the produced gas concentrate in the reboiler and bake onto the firetube, causing hot spots and eventual firetube failure. Glycol that has been overheated or contaminated turns dark and acidic. A cool reboiler means wet lean glycol and off-spec gas; an overheated one means degraded glycol and corrosion. Because the reboiler sets glycol quality, a problem here shows up as a drying failure everywhere downstream.
Operators focus on reboiler temperature above all, watching that it holds steady inside the window, along with the burner or heat source status, the still column overhead temperature, and the resulting lean glycol condition. A drifting reboiler temperature is often the earliest warning that a dehy unit is heading off spec.
A cloud SCADA such as Merobix reads the reboiler temperature, firetube or burner status, and related tags over Modbus and trends them continuously. Across a fleet of unmanned dehydration units, that lets an operator see immediately when a reboiler drifts low - so the glycol is not regenerating and the gas is about to go wet - or spikes high toward the TEG degradation limit. Alarming on the reboiler window is one of the highest-value monitoring points on the whole unit, because so much of the unit's performance flows from it.
It regenerates rich glycol by heating it until the absorbed water boils off as vapor, which leaves through a still column. That restores the glycol to a lean, dry, water-hungry state so it can be pumped back to the contactor and reused. The reboiler is the regeneration heart of a glycol dehydration unit.
A TEG reboiler is typically held around 190 to 200 degrees C. That is hot enough to boil the absorbed water out of the glycol but kept below about 204 degrees C, where triethylene glycol begins to thermally degrade. Holding this window is critical: too cool and the glycol stays wet, too hot and the glycol breaks down.
The contactor is the absorption side - a high-pressure tower where glycol picks up water from the gas. The reboiler is the regeneration side - a fired vessel that boils that water back out at low pressure so the glycol can be reused. The two run at opposite conditions and together form the continuous glycol cycle.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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