4 replies to this topic

[Alestino]

Hi,
I'm doing a simulation with Hysys but I have a problem. I'm using many conversion reactions, about 5, but we can simplify in just one global reaction: H2O--> H2 + 0.5 O2 . So, I have only one H2O stream input in the process, and only two stream output: H2 and O2 ...all the other substances recycle in the closed loop of the process. If the inlet stream of H2O is 3.6 Kmol/h , I don't achieve 3.6 Kmol/h of H2 and 1.8 Kmol/h of O2, but about 3.5 and 1.77 ...so the material balance is not satisfied...Could you give me an idea? where is the problem? ...If you need some other information please tell me...Thank you..

[Padmakar Katre]

Dear,
I think you are doing some mistake in reaction section of the Hysys Simulation Basis manager. As far as material balance is concerned its so straight and simple. Water is feed and net outlets are Oxygen and Hydrogen.

H2O = H2 + 1/2 O2 i.e. 1mol of H2O = 1 mol of H2= 1/2 mol of O2.

So as per your feed you should get the same moles of H2 as water in feed and half of the moles of the O2. Just need the configuration (sketch with the reactions configured as you told some 5 reactions are configured) which could help us to help you better.

[Alestino]

Thank you for the reply, and excuse me because I described my problem approximately. However, my conversion reactions are:
1- SO2 + I2 + 2H2O --> H2SO4 + 2HI
2- 2HI --> H2 + I2
3- H2SO4 --> H2O + SO3
4- SO3 --> SO2 + 0.5 O2

So the global reaction is H2O --> H2 + 0.5 O2

The process consist in three sections; In the first the reaction 1 occur with some excess of iodine and water. After the separation of the two phases, there are the other two sections: The concentration and decomposition of sulfuric acid (reactions 3 and 4) and the concentration and decomposition of HI (reaction 2). With an appropriate system, I recover H2 and O2 that are the only two outlet streams. An input of water is needed, but all the other substances recycle inside the closed cycle.
I can tell that is not a problem of recycle, because all the parameters of the recycle tab are set to the lowest sensitivities.
If you need other information please tell me, I'm very glad that you can help me. !

[joerd]

See my reply in your other topic, about recycle convergence tolerance.

[Alestino]

OK thanks to all...I have solved my problem ...Thanks...