4 replies to this topic

[GasPro]

All

I want to fist say that the information that is being dispersed on this forum is excellent. Let's keep it up!

I want to know if there is an issue that is associated with fluctuation of feed gas inlet to the absorber of a bulk H2S / CO2 removal unit using MDEA?

I think that with this fluctuation in feed temperature it will create a problem with the lean amine temperature to ensure the 5 degC delta is achieved. This delta is meant to prevent condensation of hydrocarbon...

Any thoughts anyone?

Edited by GasPro, 15 August 2010 - 08:10 AM.

[Zauberberg]

Operating AGRU with amine temperatures lower than 25 degC (particularly MDEA) makes the operation of Absorber extremely difficult, due to substantial increase of amine solution viscosity. This is important thing to be remembered.

With lower amine temperatures, the following happens:

- Higher capacity and faster absorption of H2S;
- Slightly lower affinity towards CO2;
- Higher co-absorption of hydrocarbons;
- If, for any reason, colder amine starts to condense hydrocarbon vapors, a second liquid phase will form inside the Absorber, leading to foaming and premature flooding.

The 5 degC rule of thumb is related to hydrocarbon dew point, not a general temperature difference criterion. If you have lean gas feeding the absorber, condensation of hydrocarbons will not take place even if the amine is substantially colder than the feed gas. You can check the dew point of your system very easily.

[GasPro]

Thanks for the response. My operating temperature is 44-55 degC from night to day respectively. This temperature fluctuates with the ambient. Is there any issues that will arise resulting from this.

Regards
GP

Edited by GasPro, 16 August 2010 - 01:23 AM.

[Zauberberg]

The amine unit you have there has probably been designed for such ambient conditions, and amine circulation adjusted accordingly. Unless there are some paticular issues you have observed in the unit operation and would like to discuss about, I can't say much more than what I have written in my previous post.

Best regards,

[GasPro]

Thank you for you assistance with gaining a better understanding of this issue.

Regards