5 replies to this topic

[Jack Bauer]

Hi all,
I'm about to start a modelling on ethylene feed treating.
In my hand I hv a material balance of the treating unit. I've done few simulation works previously but this one is new challenge for me.
In the material balance table, the component fraction are presented in PPMV (ppm volume) and PPMWT (ppm weight) and %VOL.min (percentage volume minimum-for ethylene). So I'm little bit blank on how to proceed in defining the component fraction.

Please see attached mat bal table.
Appreciate your advice. Let me know if you need more explanations.

TQ,
JB

Attached Files

•  Image1602.jpg   1.15MB   20 downloads

[Zauberberg]

There should be no confusion with respect to feed definition: PPM (weight or volume) is equivalent to 1/10,000 fraction of %, or 1E-06 fraction of the total sum of fractions (=1) of all components together.

So if you decide to define the feed e.g. on a weight basis, 5 ppmw would be equivalent to 0.000005 weight fraction. It isn't more complicated than that.

[Jack Bauer]

There should be no confusion with respect to feed definition: PPM (weight or volume) is equivalent to 1/10,000 fraction of %, or 1E-06 fraction of the total sum of fractions (=1) of all components together.

So if you decide to define the feed e.g. on a weight basis, 5 ppmw would be equivalent to 0.000005 weight fraction. It isn't more complicated than that.

so, according to the mat bal table, my ethylene is 99.9% and the rest are the traces component?
and the remaining of 0.01 is the summation of those traces?

[Zauberberg]

Actually the remaining percentage is 0.1% vol and not 0.01% as you wrote (Ethylene is 99.9% vol).
0.1% vol is equivalent to 1,000 ppmv.

[Andres Valencia Michaud]

There should be no confusion with respect to feed definition: PPM (weight or volume) is equivalent to 1/10,000 fraction of %, or 1E-06 fraction of the total sum of fractions (=1) of all components together.

So if you decide to define the feed e.g. on a weight basis, 5 ppmw would be equivalent to 0.000005 weight fraction. It isn't more complicated than that.

so, according to the mat bal table, my ethylene is 99.9% and the rest are the traces component?
and the remaining of 0.01 is the summation of those traces?

My advice is to take all the components and work with them in a molar basis. Because you have the mass flow you can calculate the sulphur moles (the only stream with ppmwt) and using the volumetric flow at normal conditions, you can calculate the rest of the components (because ppmv is a definition made at these conditions and not at the operation temperature and pressure variables), then, of course your ethylene is 99,9% pure.

[Jack Bauer]

There should be no confusion with respect to feed definition: PPM (weight or volume) is equivalent to 1/10,000 fraction of %, or 1E-06 fraction of the total sum of fractions (=1) of all components together.

So if you decide to define the feed e.g. on a weight basis, 5 ppmw would be equivalent to 0.000005 weight fraction. It isn't more complicated than that.

so, according to the mat bal table, my ethylene is 99.9% and the rest are the traces component?
and the remaining of 0.01 is the summation of those traces?

My advice is to take all the components and work with them in a molar basis. Because you have the mass flow you can calculate the sulphur moles (the only stream with ppmwt) and using the volumetric flow at normal conditions, you can calculate the rest of the components (because ppmv is a definition made at these conditions and not at the operation temperature and pressure variables), then, of course your ethylene is 99,9% pure.

Zauberberg, Andres Valencia Michaud, thanks so much for your replies.
will proceed with the simulation as per your guys input and will shout again if i stuck somewhere.

Edited by Jack Bauer, 23 December 2009 - 07:28 AM.