2 replies to this topic

[CHEMSTRONG]

Hi all,
I have maintained excess air to the tune of 15 percent in fired Heater Aspen EDR. But still I m not getting desired flue gas temp at the radiation section outlet. Also I have made Stack temp loss in EDR as zero as my understanding is that Datasheet gives convection section outlet temp and not stack outlet temp. Is it correct understanding ? Also in my case 4 heaters radiation section flue gas goes to common convection box.For radiation section of heaters, i got thermal efficiency as 55 percent only..Also I want to know how Fuel gas Heavy Aromatic Naphtha composition in my case plays a role in outlet flue gas composition.

Please help me. In Aspen EDR, my tube areas are matching with that of Datasheet values.

Regards,
Chetan Chavan

[CHEMSTRONG]

I have got 10 percent higher flows of process fluid in model as compared to datashert valyes. STILL my heat duties are 10 percent in model lower than that of datasheet.I hv LHV of fuel as 10268 in hysys kcal.

[Saml]

Chetan, you are explaining the problema as if we knew what your situation is and what issue you are trying to troubleshoot by doing this simulation. Also, what variables are fixed,what are you calculating, what mode are you running EDR (design, simulation, rating) etc? etc?

 

55% exchange in radiation section may be a good value. So the "only" may depend  on your specific application.

 

Then "Fuel gas Heavy Aromatic Naphtha" is something difficult  to understand. ¿Are you burning heavy aromatic naphta?

 

What do you mean by "desired". It is a very vague term: It is what your manager desire, what you measure in actual operation or what is stated in the original datasheet?

 

Your second post makes it worse. You increased the process flow (where the heat duty depends on Cp) but then compare with the LHV of the fuel (without specifying the units. It is that kcal/kg? per liter? per Nm3?)