12 replies to this topic

[vijoyalchemy]

Dear professionals,

 

I am presently working as a production engineer in an ammonia plant. In our plant, we use BASF's aMDEA (Activated methyl diethanol amine) solution for absorbtion of CO2 in the process gas.

 

We use BASF's amerel 1500 as an anti foam agent for this system.

 

Please let me know the working mechanism of this anti-foam agent.

 

Thank you

[latexman]

I recommend contacting BASF.  Your company paid good money for the anti-foam.  BASF owes you an answer.

[Pilesar]

Antifoams derived from silicone lower the surface tension of the liquid so the bubbles no longer hold together.

[vijoyalchemy]

Thanks Pilesar. But then soap solution also lowers the surface tension of water but it produces foam ..why?

[Pilesar]

Your soap solution observation is interesting -- personal observation teaches me that bubbles in the bathtub are incompatible with bar soap. So perhaps it is the mixing of two different types of foreign substance that causes the foam to break? Too much silicone antifoam can cause foaming problems, too. This is why you have to limit the additive rate in your amine system.

[vijoyalchemy]

So you mean to say that, if added in small quantities, anti foam reduces the foaming by reducing surface tension but if added in excess, it may further aggravate the problem. Right?

[vijoyalchemy]

Also, what effect will temperature have on the foaming tendency of the amine solution?

[Pilesar]

Too much antifoam can cause foaming problems. High temperature can increase the degradation products in the amine solution resulting in a higher tendency to foam. Filtering and reclaiming help reduce foaming by improving solution quality.

[vijoyalchemy]

Thank you so much

[Satyajit]

Vijay,

         High temperature will have  few impacts on your solution:

1. Loss of piperazine which is quite volatile compared to AMDEA and therby reduces absorption capacity of CO2 .

2. Degradation of MDEA into HSS ( heat stable salts) leading to corrosion , foaming ; it also reduces CO2 absorption capacity as active content of AMDEA is reduced.

3. Less heat transfer in the reboiler as the delta T between process gas and solution is reduced; you might need to increase S/C ratio in the front end.

4. Increase of temperature is linked to regenerator pressure ( will increase pressure); good for CO2 compressor but CO2 loading in semilean and lean solution will increase and will influence  CO2 absorption.

 

Remember, root cause of foaming is not the temperature of amdea solution.

 

However based on above points, I can say that increase in temperature of amdea solution  will increase foaming tendency in long run.

Kind regards,

Satyajit

[babak404]

Hello friends
We use amerel 1500 in our CO2 treatment section of our ammonia plant as antifoam.
Can anybody suggest me any other antifoam agent?
many thanks

[breizh]

Babak404

 

Why do you want to change ? Did you talk to your supplier ? 

 

Breizh 

[Ajiz]

Dear All,

 

How do you estimate amount of antifoam that required for your systems?

 

Thank you.