4 replies to this topic

[siraj paracha]

We have a BASF aMDEA based CO2 removal system in our ammonia maufacturing facility. Since long we are facing an abnormal behaviour of the system. The detail goes like this

 

The system when ever is taken in service either it is a hot or cold startup, it do not takes full load immediately and always gives CO2 slippage whereas all the conditions which are required for effecient CO2 loading in solution are met like lean & semi lean solution flows, Absorption column pressure, lean solution temperatures and concentration.

 

This condition prevails for around 1 month due to which plant remains at low load. After 1 month system gradually stablizes automatically on the same conditions and CO2 slippage decreases and even becomes Zero at times. 

 

My question is about aMDEA solution CO2 loading behaviour, like any one have idea or experienced this kinda of aMDEA solution behaviour. Is this normal or not?

 

If not what could be the possibility like we have tried to increase its amine concentration to 45 %, we have checked the heat stable salts concentration in it and found normal. We try to keep the foam hieght at design conditions but still we face this problem after startups.

 

Is there any chemistry involved in this delay?

 

Your expert opinion is required.

 

Thanks

[Bobby Strain]

I would consult BASF.

 

Bobby

[siraj paracha]

Thanks but ...

 

We are in contact with BASF but what the actual problem is that we are running plant at a load of 120 % FE where as vendor says that the system is designed for 100 %. Behaviour of the CO2 Removal system at 120 % FE load after Startup is different and it becomes normal at same 120% FE after few days.

That is why i have circulated this problem here that if any one has experienced this kinda problem he can share his knowledge with us.

[Bobby Strain]

You are likely to be moving particulate matter around whenever you shut down. This will cause a bit more foaming, reducing the contact time in the absorber. Lower contact time leads to CO₂ slip. So, best to be patient when you restart. And be sure to keep the solvent clean with proper attention to the slipstream filtering.

 

Bobby

[siraj paracha]

we have a side stream filters & Carbon filter as well for the removal of Suspended solids and organic matter. Both filters remain in service through out the operation. Yes SS quantity in our system is currently at 20 ppm against design of < 10 ppm but the quantity is same i,e. after startup & currently. Do you think this high quantity may cause system to slip CO2??

What can we do other than filters to lower the SS quantity?

Edited by siraj paracha, 30 May 2016 - 03:01 AM.