29 replies to this topic

[PingPong]

Unfortunately we have no say over the modern education systems where emphasis seems to be mainly on making nice looking reports instead of actually learning something and developing insight.

 

Once again JaiEdi: you need to revise your BFD as that is not workable.

 

About separation in DeC2:

the column makes a split between an ethane & lighter distillate and a propylene & heavier bottoms product.

There is a maximum amount of propylene that one would allow in the distillate as this would end up in the recycle ethane (C2 splitter bottoms) to the furnace coils and would there cause fouling. Moreover it would be a loss of a valuable product. Limit of propylene in DeC2 distillate is an economical choice really. Too much would cost revenue, too little would cost energy and investment in the DeC2.

The amount of ethane you allow to be lost in the C3+ bottoms product depends on its application. If a C3 splitter is included then it is set by the maximum allowable amount in the propylene product. If there is no C3 splitter and C3+ is a plant product, it is partly an economical choice, but there can also be a C2 limit imposed by the receiver of that C3+.

 

In any case it makes no difference for the required separation whether the DeC2 is located upstream the chilling train (front end) or downstream the DeC1 (back end). Its the use of the products that sets the required separation by means of the product specs.

Edited by PingPong, 20 February 2021 - 05:37 PM.

[JaiEdi]

We know what the product specification is and we have assumed sharp split. But we have been asked to find strong references for separation efficiencies of the columns to base our ball park mass and energy balances. There is plenty of literature on this for front end demethanizer approaches but I cannot find any existence of this for de-ethanizer approaches. 

 

 

The licensors won't respond to your request. You can easily determine the required separation from the product specifications. It's a shame that you must waste so much time on this rather that learning fundamentals.

 

Bobby

[JaiEdi]

So are you saying to just set an allowable amount of propylene in the distillate and set an allowable amount of ethane in C3+ bottoms? 

 

 

Unfortunately we have no say over the modern education systems where emphasis seems to be mainly on making nice looking reports instead of actually learning something and developing insight.

 

Once again JaiEdi: you need to revise your BFD as that is not workable.

 

About separation in DeC2:

the column makes a split between an ethane & lighter distillate and a propylene & heavier bottoms product.

There is a maximum amount of propylene that one would allow in the distillate as this would end up in the recycle ethane (C2 splitter bottoms) to the furnace coils and would there cause fouling. Moreover it would be a loss of a valuable product. Limit of propylene in DeC2 distillate is an economical choice really. Too much would cost revenue, too little would cost energy and investment in the DeC2.

The amount of ethane you allow to be lost in the C3+ bottoms product depends on its application. If a C3 splitter is included then it is set by the maximum allowable amount in the propylene product. If there is no C3 splitter and C3+ is a plant product, it is partly an economical choice, but there can also be a C2 limit imposed by the receiver of that C3+.

 

In any case it makes no difference for the required separation whether the DeC2 is located upstream the chilling train (front end) or downstream the DeC1 (back end). Its the use of the products that sets the required separation by means of the product specs.

[PingPong]

Yes, to be more precise: the allowable amount of propylene plus MAPD in the distillate, and an allowable amount of ethane in C3+ bottoms. The latter depends on whether there will be a C3 splitter or not.

[JaiEdi]

Yes we are using a C3 splitter

Yes, to be more precise: the allowable amount of propylene plus MAPD in the distillate, and an allowable amount of ethane in C3+ bottoms. The latter depends on whether there will be a C3 splitter or not.