Avoid Amine Degradation in Stripper Reboiler

Hi

Amine sweetening is one of the most famous and common processes in gas plants. Within this process, there are several considerations to ensure a smooth operation with minimum issues. I have talked about some of these considerations in a previous article Design Considerations in Amine Gas Sweetening Systems.

Here I want to highlight one of these considerations, which is related to the amine stripper reboiler. In an Amine stripper, we target the separation of acid gas from rich amine so that we can reuse the amine again in the Amine absorber.

The main heat source for stripping is either hot oil or steam at the stripper reboiler. It heats the amine to strip the acid gases from the rich Amine through several stages.

As we increase the heating medium temperature, this would be better for separation. However, if amine outlet temperature was above 140 C, several issues occur, we commonly see a cascade of operational problems including corrosion, thermal degradation of the amine solution, foaming, salt formation, excessive fouling and reduced absorption efficiency of the recycled amine.

That’s why The industry standard is to maintain this temperature between 120-140°C. The exact temperature depends on several factors such as:

• Amine Type: Different amines (MEA, DEA, MDEA, etc.) have varying thermal stability thresholds
• Solution Concentration: Higher concentrations may be more susceptible to degradation
• Inhibitor Package: The presence and effectiveness of your corrosion/degradation inhibitors
• System Pressure: Operating pressure influences the thermal stability of your solution

How to Avoid Amine Degradation?

To keep the temperature within this limit, we shall need to carefully control the inlet temperature of the heating medium not to exceed around 150 C so that the skin temperature in the reboiler won’t cause Amine degradation.

So for example in case of steam, we shouldn’t use a saturated steam of more than 50 psig. Otherwise, if steam with a higher pressure is the only available steam, then we need to use a desuperheater. In case of using hot oil as a heating medium, there should be means to control its inlet temperature.

So that's it today, still you can see other design considerations in Amine process in the article Design Considerations in Amine Gas Sweetening Systems.

If you have any questions or suggestions, feel free to reply to this email.

Regards

Mohamad