3 replies to this topic

[pawan]

In Ethylene oxide manufacturing, EO is separated from recycle gas through 2 stage absorption & 2 stage stripping using water. This consumes lot of energy.

Can anybody suggest any direct one step method to remove EO using any other technology e.g. adsorption OR some other physical solvent?

[Padmakar Katre]

Dear Pawan,
In Ethylene oxide manufacturing,
As you told the method to get EO is accepted one for safety point of view because to handle EO is a difficult and not that safer beacuse its flammabiliy limit 3-100 % and very low TLV so the current process to recover EO from cycle gas by water absorption is the best method as per me as EO has 100% solubilty in water provided your absorption temperature doesn't exceed 37 Deg C irrespective pressure so this is the most feasible process and the another thing is that the conc of EO in cycle gas is not more than 2-2.5 % , used solvent is water,its easy availability as well the reaction products like CO2 will not allow to have different process apart from this conventional one, I think these are the parameters which are stronger over the other methods to recover EO from cycle gas.If any one has a different opinion, he/she is always welcome to share their comments in this forum........

[pawan]

Thanks Mr Katre
I agree, but as I said in my other post Theory & Practicality are 2 different things.

Also I do not believe in conventional technologies as a process technologist otherwise there is no attraction/charm in the life of a process/chemical engineer.

So I always search for better & latest technologies.

The reason.....

you need lot of water for 1st stage absorption.
Then lot of energy for stripping.
Then again lot of water for 2nd stage absorption.
Then lot of energy for stripping.
Then lot of energy for process contaminated water treatment due to acidity etc....

Unfortunately I could not put my efforts in this direction so I posted it on this forum.

Similarly I believe that there must be some other better way (Other than multistage evaporation) to separate out MEG from 12% solution at reactor exit.

Your view....

[Padmakar Katre]

Dear Pawan,
I agree with what you are trying to convince. But a process engineer should have a good sense of process economics and feasibility of what he thinks.If we want to avoid the subsequent stages i.e. stripping and absorption and once again stripping the basic problem is with scrubbed components from Cycle Gas i.e. ethylene,ethane,methane, nitrogen,argon and carbon di-oxide whcih are most important inorder to avoid the extra costs needed to have your downstream of SS.In any EO-EG plant from your second stage stripper onward downstream is of CS which is a good deal of equipments.If there is any solvent present where we will have selective absorption of EO from Cycle Gas leaving the other components.But as such solvent I didn't come across.
And regarding the EG concentration and subsequent purification the present technique i.e. of having multi-effect evaporation and the subsequent purification/distillation columns is the only option I find the best because if you will ask to any process engineer regarding to concentrate the solute from very low conc. to desired one any one will first think of having the evaporation opertaion compare to what available unit operations are there. One operation we can think that is adsorption where EG will retain on the selected adsobent/resins and allow water to pass but I don't think it will be a good choice for large scale production.
I worked with EO-EG plant for 2.5 yrs and currently working on the same project in India.i have so many times discussions with the friends and seniors but the feasibiilty and process economics was always the point where we used to give up what we thought about the modifiactions in the existing technology.
I will be thankfull to you if you share your ideas regarding the same.
Looking forward to see your reply.......
Cheers........Njoy............