Question about conversion reactors in Hysys

**saifthamer83** · 03-19-2011, 05:40 PM

Hi

I am just wondering whether the duty should be set to heating or cooling in the conversion reactors if the reaction is exothermic? (my bets on cooling to get rid off the excess temperature from the reaction)

Is there a way to the set the reaction temperature? or is it set by inputting the temperatures at the outlet streams?

The reactor has to be running at 450C, I set the temperatures at the outlet streams for the reactor.

Sorry for typing in English don't have Arabic language nor keyboard here.

Thanks for the help........

Cheers

**chemnguyents** · 03-21-2011, 05:31 AM

with conversion reactor, you always get the product stream specifications and conditions. I think we will talk more detail if you can share more thing about your reaction.

**saifthamer83** · 03-21-2011, 07:22 AM

hey thanks for the reply, its a simple Ammonia production from Nitrogen, Hydrogen and Argon...

the conversion rate of Hydrogen to ammonia is 20%..

[IMG]http://img819.images****.us/img819/1466/24224543.jpg[/IMG]

I am trying to find the best temperature for the inlet stream 2 to the reactor just after the heater..

Feed to heater is 25C, reactor temp is 450C........ any temp between 25 to 450 will do the case but its a matter of saving energy..

since its exothermic reaction, is it possible to use the heat generated from the reaction?

Thanks

**chemnguyents** · 03-21-2011, 07:52 AM

Reaction: H2 + N2 -> NH3 is equilibrium reaction and exothermic. Ammonia production rate and equilibrium are in reverse order. So you can not find the optimum temperature for this reaction if you use conversion reactor. With conversion reactor, you can not know how temperature influence to your reaction (rate, Keq). If you still want to find the best temperature for ammonia synthesis, you can follow these step:

1.Define reaction (two reaction):
a. Define again your reaction with equilibrium reaction type and add Keq vs T of ammonia synthesis from tab library
b. Add ammonia synthesis reaction with kinetic reaction type and find out A and E, A' and E' for this type (aspen sample have it, so you can use)

2.Return to PFD and add Equilibrium reactor and Plug Flow reactor in parallel with two feed stream in parallel.

3. Now you can do any thing you need.

**saifthamer83** · 03-21-2011, 09:28 AM

Hi again,

Thanks for the info, but I am unable to do it, its my 1st time to use hysys with reactors

I added a 2nd reactions which is equilibruim and added the reaction formula from the reaction library tab and choose Keq vs T in basis tab but didnt now from where to choose the ammonia.. I also added the conversion % and reaction temperature in approach tab

then I got stuck :-)
is it possible to add a detailed procedure by any chance or I can send u the case and u modify it?

cheers mate