Excel library for process calc's including distillation

[cbadia]

I am calculating a separation column for a mixture of benzene, toluene, xylene in Prode Properties,
I see that different specifications are available as component fraction (at top or bottom) and component recovery (at top or bottom) in addition to reflux, ratio of flows, side drawns etc.
My question is, how does Prode Properties manage component fraction and component recovery when I specify a side drawn ?

[carlo.stenali]

> I am calculating a separation column for a mixture of benzene, toluene, xylene in Prode Properties,
> I see that different specifications are available as component fraction (at top or bottom) and component recovery (at top or bottom) in addition to reflux, ratio of flows, side drawns etc.
>My question is, how does Prode Properties manage component fraction and component recovery when I specify a side drawn ?

in Prode Properties specifications are quite simple to define
-if you specify a component fraction at top (or bottom) the solver attempts to find a solution where the specified component is present with the desired molar fraction in top or bottom stream, for example if you specify water at 0.999 the solver finds a solution where water is present with a molar fraction 0.999 in top (or bottom) stream, this specification could be impossible to solve if you specify in addition flow rates etc., a common case is when you have a feed with a certain flow of component n, if you specify for that component a molar fraction at top = 0.9999 the solver will be unable to solve any specification with distillate flow rate > flow of that component at inlet, the same for side drawns
-in general I prefer to specify a component fraction recovery (at top or bottom), this is much more flexible since it is independent from top, bottom and side drawn flows, the solver attempts to find a solution where the flow of the specified component equals feed flow * recovery fraction
Hoping this helps.

[cbadia]

thanks Carlo,
I understand that it is better to specify a fraction recovery where possible.
That should solve also the convergence problems found with side drawns...

[acar]

thank you very much,
I have found Prode Properties very good and I recommend it !!

[mdep]

has anyone attempted to model solid precipitation (liquid-solid SLE equilibria) in Prode Properties with Peng Robinson or Soave-Redlich-Kwong models?
I have base version (no CPA or SAFT included) , I am not sure if a standard EOS can do the work,
thank you for assistance in this matter !

[carlo.stenali]

you may obtain reasonably good results for hydrocarbon's liquid-solid equilibria in Prode Properties utilizing Soave Redlich Kwong or Pend Robinson models but that depends from composition, with very heavy components a statistical approach (SAFT) can offere several advantages, in most cases CPA is a good alternative.

[sayedfarhanali]

Thanks for Sharing Nice source for Calculations

[mdep]

thanks carlo.stenali,
I wish to evaluate the fraction of heavy component's (C10+) which will precipitate when temperature goes below -10C
Prode Properties is able to calculate the solid fraction but I have not tuned the model and kijs for heavy components are set to 0.0
I have not idea how the accurate are the results.

[carlo.stenali]

if mixture doesn't include water and similar components (only hydrocarbons and inerts) then Peng Robinson or Soave Redlich Kwong may be able to do the work,
differently I would suggest a model as SAFT or CPA (Cubic Plus Association) with inclusion of association contribute.
Prode Properties (extended version) includes SAFT and CPA, you may contact the developer for additional information
"http://www.prode.com"

[acar]

Carlo, does the CPA and SAFT models in Prode Properties include the association contribute ?

[carlo.stenali]

in my version (extended) of Prode Properties, CPA (Cubic Plus Association) and SAFT (Statistical Associating Fluid ...) do include these assciation schemes

1a,
2a
2b
3a
3b
4a
4b
4c

as far as I know 1a is for organic acids, 2b and 3b for alcohols and so on...
I have little experience with SAFt as I utilize mainly CPA for mixtures of hydrocarbons with water.

[acar]

thanks Carlo,
the reported association schemes should permit to model glycols, water and alcohols which are the chemicals which interest me.