2 replies to this topic

[Hasam ullah]

Hi

   First of all I would like to thanks all of you for attention and sincere help. I have to design a reactor in which tri-pentyl-ammonium-butyrate is decomposed into butyric acid and tri-pentyl-amine.  The boiling point of butyric acid at atmospheric pressure is 163 ^oC.  In this reactor vacuum is generated to decrease the boiling point to 90 ^oC.  I have also attached a pfd of this process.

 

The vapours of butyric acid go into a condenser at the top and tri- pentyle-amine is separated from bottom.  My question is can we take the condenser temperature 85 degree c?  because in the next step butyric acid need to be heated again.second what would be the change in temperature when butyric acid is shifted from vacuum to atmospheric pressure.  Third how butyric acid can be transferred from vacuum to atmospheric pressure.  Please reply.  I would be very Thankful to u all.

 

 condensor pfd.docx   220.42KB   14 downloads

[samayaraj]

Hi Hasam,

 

You mean the butyric acid is coming out of condenser is 85 Deg. C? In general condenser are used just to remove the latent heat from vapor. But in actual cases, this will not happen. The saturated liquid will be subcooled by 1 or 2 deg. C near the bottom of condenser. Hence 5 Deg. C difference is more i feel.

 

When you transfer the satd. butyric acid from low pressure receiver to atm. pressure, temperature will be dropped due to loss of heat from piping and other system. You have to provide sufficient insulation to reduce the heat loss. Also a small amount of heat heat will be added by pump. Hence, the temperature of stream depends on length of piping, thickness of insulation, type of cladding, atm. condition and efficiency of pump. 

 

In the attached PFD, you have shown a pump to transfer the acid from low pressure receiver to atm. provided the pump is having sufficient NPSH. 

 

 

#Samayaraj

Edited by samayaraj, 10 December 2014 - 10:50 PM.

[Aneken]

Vaccum to Atmospheric concept:

 

Generally in case of any gas or liquid if we pressurize it the temperature increases .

 

Thermal diffusivity is a function of pressure. Under constant pressure, as samayaaraj told that "temperature will be dropped due to loss of heat from piping and other system", butyric acid being have very high conductivity thus thermal diffusivity.

 

But under changing pressure scenario, i have doubts and would be glad if someone clears it.

Edited by Aneken, 10 December 2014 - 11:48 PM.