What is Glycol Foaming?

One of the biggest challenges in operating a glycol gas dehydration system is addressing glycol loss. Most dehydration units are designed with a margin of 0.1 gallons of glycol per million feet of natural gas treated. If the system loses more than this, processes are affected. One of the most common ways glycol is lost is through foaming.

Foaming happens when entrained hydrocarbons from production enter the glycol fluid. As the entrained glycol is processed through the contactor tower—also referred to as the absorber—, it will carry over the top of the absorber with the sales gas when stable foam builds up on the trays.  Foaming also causes poor contact between the gas and the glycol, significantly reducing the drying of the gas. Glycol foaming is one condition that leads to glycol loss.

Glycol Gas Dehydration System, Glycol Loss, Glycol Foaming

Glycol Gas Dehydration System

How To Address Glycol Loss Due to Foaming

In order to dehydrate natural gas properly, a dehydration system needs clean glycol that is free from hydrocarbons and any other impurities that may be present. If you encounter foaming, your first step can be to lower pressure and use an anti-foaming agent to temporarily reduce the foam and continue processing gas. However, this is a temporary fix.

To address the underlying issue, the best solution is to examine your filtration system and consider adding a carbon filter. Carbon filters are designed to remove dissolved impurities from the glycol solution.

If you have added a carbon filter and are still experiencing foaming and/or glycol loss, here are a few other things to check: 

  • Glycol can be lost in the glycol reboiler due to excessive temperature. Temperatures above 400 F cause the vaporization and/or thermal decomposition of glycol. In particular, excessive top temperatures in the still column of the reboiler can allow vaporized glycol to escape from the to atmosphere with the water vapor.
  • Excessive turbulence and high liquid-to-vapor contacting velocities can also cause the glycol to foam.  This condition may point to underlying mechanical or chemical issues.
  • Other causes of foam that may be present in the process fluid include field corrosion inhibitors, salt, or finely-divided suspended solids.