5 replies to this topic

Dear all,

When I modify a Distillation Column, I want to modify a prebuilt column by replacing the generic reboiler with a HE. I also change the Column Solving Method to MODIFIED HYSIM INSIDE-OUT ( Parameter-solver). The bottom stream of the column is named " To Reboiler". Anh I can not attach it as the inlet of the pump ( to push the fluid through the HE). When I put stream " To Reboiler" as the inlet of this pump, HYSYS occur message error.

Please help me in this case. Thank you very much

[Padmakar Katre]

Dear,
Enter in the column environment first delete that stream or disconnect from both ends (to and fro) create another stream going to the pump suction from the column bottom this will solve your query. After pump discharge put a TEE operation and have the pump discharge flow splitted into 2 stream out of which one wil go as reboiler inlet and the other will go as your bottom product. Now you can specify the spec in the Design-Monitor page for the TEE split i.e. % of the flow through the reboiler and the other one will be fixed automatically.
I hope this will solve your problem. Is your reboiler a forced-syphon one if so then only put the Pump else you could give the Delta P across Reboiler as zero and just put the TEE which will take feed from the column bottom instead of the pump discharge.

Dear Padmakar: Thank you very much for your instruction. Now I can solve my last query. Anyway, I can not converge the column, I don't know what specs I will activate for the degree of freedom is zero. I will try to think more about this, but can you recommend me how to do this easily, because now I have no esperience about this. Thank you.

[Padmakar Katre]

Dear,
I hope that you will have 3-4 degress of freedom and to make it zero you need to make 3-4 specifications active out of which one has to be the splitter spec. i.e. the percentage flow split. And rest you can decide like column top product flow, bottom flow, any of the temperature or products purities and so many.
The main reason which I could guess is you TEE split spec is either for just estimate and not active. Please make it active by making any other spec inactive i.e. just for estimate and confirm that the degress of freedom are zero after that run the column. It should solve your problem. Waiting for your comments.

Dear Mr. Padmakar,

Thank you very much for your help. I am sorry because I don't reply your comments. Now I have an accident so I can not work now. It have taken me 2 months to overcome. I will come back as soon as I can. Thank you so much.

[Padmakar Katre]

Dear,
Not an issue first get recover and then revert back. Hope you to recover soon. Take care.