TEG Natural Gas Dehydration Contactor & Reboiler Calculator

Triethylene glycol begins irreversible thermal pyrolysis above 206°C (404°F). Localized hot spots on firetube surfaces break TEG down into volatile organic acids (formic, acetic) and heavy black polymers. The pH plummets from 7.5 to below 4.5, dissolving carbon steel reboiler shells and creating severe foaming that shuts down gas export pipelines.

If lean TEG enters the top of the contactor colder than the incoming natural gas ($T_{glycol} < T_{gas}$), heavy hydrocarbons ($C_6+$ hexane, benzene, toluene) condense directly out of the vapor phase into the glycol. Hydrocarbon liquids drastically lower surface tension, triggering uncontrollable foaming that carries tens of barrels of glycol into the dry gas export line.

Trace $H_2S$ in natural gas reacts with steel piping to form sub-micron pyrophoric iron sulfide ($FeS$) fines. Circulating through high-pressure glycol charge pumps without continuous full-flow 5-micron sock filters and activated carbon bed adsorption, black $FeS$ slurry cuts tungsten carbide mechanical seal faces within weeks, leaking high-pressure glycol to atmosphere.

If the upstream 2-phase/3-phase inlet scrubber fails or dumps high liquid levels, produced formation water laden with sodium chloride ($NaCl > 50,000 ext{ ppm}$) enters the contactor. Dissolved salts cannot vaporize in the reboiler; they bake directly onto the submerged U-tube firetube bundle. The salt crust insulates the metal, causing localized metal overheating ($>600^circ ext{C}$) and catastrophic firetube rupture.

The atmospheric still column mounted above the reboiler utilizes an internal or external reflux cooling coil (condensing ascending glycol vapors while venting pure steam). If reflux cooling water flow fails or rich glycol bypasses the coil, vapor temperature at the still column top exceeds 105°C (221°F). TEG vapor escapes directly to the flare or atmosphere, causing massive glycol consumption losses ($> 1 ext{ lb TEG / MMSCF}$).