3 replies to this topic

[chrbac]

Hi all, I'm trying to simulate removing CO2 from an amine complex.  We're designing a switchable polarity solvent called cyclohexyl piperidine (this is our paper http://www.sciencedi...11916412004055)

the reaction is

 

C10H21N +CO2 +H2 <--> C10H21NH+ + HCO3-   the reverse reaction occurs under heat.

 

Basically I need to design a column that will run the reverse reaction and separate out the CO2.  Is this possible to do in one block in aspen?  should i run a reactor to a sep block?

 

Any insight is appreciated

 

Thanks

[Lucian Gomoescu]

Hi,

 

If i understood it correctly, there is a component that can be either positive charged, either neutral acc. the reversible reaction:
 C11H21N (liq1)   +   CO2(g)   +   H2O(liq2) <--> C11H21NH+(aq)   +   HCO3-(aq).

The switch from ionic to neutral form of the solvent (i.e. reverse reaction) is endothermal.

 

I don't know exactly what are the inputs and outputs for the reactor, so i just assume:

 

*inputs:

- a stream with a known composition (C11H21NH+, H2O), pressure and temperature;

 

*reactor:

- reactor is operated continously;

- reactor is simulated as a liquid-gas separator with a heat duty;

- reaction reaches equilibrium;

 

*outputs:

- a gas stream;

- a liquid stream consisting in two liquid phases (water & solvent in neutral form).

 

It would be helpful, for determination of problem approach, to know what is the purpose of having this reactor simulated in Aspen.

Is it after all necessary to have this block within an Aspen flowsheet? If not, then it would be better to make a reactor model in MATLAB or Excel.

 

Observation: Aspen Plus and HYSYS don't have the cyclohexyl piperidine in their databank, so it has to be defined via Joback group contribution method, even more there is a real challenge to have the ionic form included in the simulation.

[chrbac]

Lucien,

 

  I've been realizing that this will probably need to be modeled in MATLAB.  We're trying to model a desalination plant in Aspen because our client wants us to, but I'm thinking that won't happen for this part.  I've been messing around with adding in the properties of CHP into Aspen, and it's yielding ok results in the rest of the model, but the degassing is becoming a mess...

 

Thank you for your insight though

 

Catherine

[Lucian Gomoescu]

Hi,

See attached an example with a separation + reaction in a single separator. It is possible for a reaction specified in a Chemistry list of reactions to happen in a separator block.

Reactions specified in a Chemistry list can take place in all blocks, while those in a Reactions list take place only in a reactor type block.

Attached Files

•  CHP2.bkp   145KB   7 downloads