2 replies to this topic

[redapples]

Hi,

I simulated a cryogenic nitrogen rejection column in Aspen (peng-robinson package) with the top vapour product, nitrogen and helium leaving at -195C and methane in the bottoms leaving at -162C.
I obtained a stream table of results, and i needed the densities of both the vapour and liquid stream (pv and pl) to calculate a column diameter.
However, aspen has given me pv and pl in units of kmol/cum, and i need to convert that to kg/m3. ive never come across kmol/cum before, any ideas on how to convert the units?
my pv is 0.16 kmol/cum, and pl=26.38 kmol/cum.
any help would be appreciated...

thanks!!
=)

[shan]

cum = cubic meter = m³

[kpavan]

Hi,

I simulated a cryogenic nitrogen rejection column in Aspen (peng-robinson package) with the top vapour product, nitrogen and helium leaving at -195C and methane in the bottoms leaving at -162C.
I obtained a stream table of results, and i needed the densities of both the vapour and liquid stream (pv and pl) to calculate a column diameter.
However, aspen has given me pv and pl in units of kmol/cum, and i need to convert that to kg/m3. ive never come across kmol/cum before, any ideas on how to convert the units?
my pv is 0.16 kmol/cum, and pl=26.38 kmol/cum.
any help would be appreciated...

thanks!!
=)

Dear redapples,
It seems you have forgotten to specify the units of density, so Aspen has taken the default units of kmol/cum.
Just select the units as kg/cum in the Units column opposite to the physical property that you have selected. It will solve your problem.

Regards,
Pavan

Edited by kpavan, 29 October 2009 - 11:08 PM.