[Armani_AD]

Hi guys

am just wondering what is the advantages & disadvantages from increasing the MDEA concentration above 55% wt to the process of amine treating unit?

where in our plant they are planning to increase the concentration of MDEA, the normal concentration of MDEA that we are use is between 43% to 45%

Kindly guys help me with this subject

Many thanks

[eugenedakin]

Hi Armani,

The advantages are:
You will be able to remove more H2S from the contactor
Less chance of corrosion due to excess MDEA on the 'sour' side of the system



Disadvantages include:
-More heat output to sweeten your MDEA
-The reboiler may not remove enough H2S and you may get H2S returning back to your contactor which is not sweet
Greater chance of corrosion on the 'sweet' side of the system
-Any system loss will be more expensive (MDEA is more expensive than water)
-Increased chance of foaming issues
-an excess amount of MDEA will cause an efficiency decrease (a certain concentration of water is required for the reaction)
-More testing required to ensure the system works 'as needed'
-Training of the staff due to a different fluid (the system doesn't work the same way is used-to)
-Greater salt intolerance

These are just a few that may or may not be an issue. There are definitely more aspects, and this should provide you with a good start.

Sincerely,

Eugene

[Armani_AD]

Thanks Eugene for your answer highly appreciated

however i have some points to add, correct if am wrong, more MDEA will absorb more H2S and more CO2, although MDEA is selective to H2S it will absorb more CO2 due to high concentration and therefore CO2 amount in the sweet gas will reduce and the clorific value will increase in the sweet gas ..

moreover i found somthing you wrote in the fourm which i consider it another information: 

(( There MUST be free and available water in order for this H2S-MDEA reaction to take place.  When the concentration of MDEA becomes too high, then there is not enough water to act as a medium for the reaction to take place, then your efficiency for sweetening decreases signifacently ))

can u make it more clear for me please ? secially ((there is not enough water to act as a medium)) ??

Many Thanks

[eugenedakin]

Hello Armani,

Yes, you are correct that you will absorb/adsorb more H2S and CO2. Less CO2 will be slipstreamed (which may increase operation fees (more heat required in the reboiler) and less CO2 in the sales gas.

Yes, I have some operators add an excessive amount of MDEA to the system which does not allow enough free water. The H2S-MDEA reaction works through water .. without water, the reaction rate slows down. The amount of free water that a system requires really depends on the specific system.

I hope this helps,

Eugene

[Armani_AD]

Thanks alot Mr Eugene for sharing your experince with me i appreciated

[eugenedakin]

Your welcome, and I hope this helps.

Sincerely,

Eugene