30 replies to this topic

[Zauberberg]

When submitting the final calculation report, try to encompass the following:

1. Calculated U-values for initial process conditions, both cases (in W/m2C);
2. Calculated U-values for final process conditions, both cases (in W/m2C);
3. Hysys-calculated U-values for initial process conditions, both cases (in W/m2C);
4. Hysys-calculated U-values for final process conditions, both cases (in W/m2C) - I believe you can get these from the Strip Chart configured to display U-values during blowdown;
5. Final temperatures as calculated by Hysys, fixed U-value;
6. Final temperatures as calculated by Hysys, continuously updated U-value;

It would be very good if you can compile all the results in an Excel workbook, so that they can be shown against each other and analyzed easily. Then we'll proceed to the next step and see how we can estimate liquid inventory during blowdown, and track the temperature profile for all cases.

[barbara_s]

Hi I compiled the xls file with all information...
thks!

Attached Files

•  U-value.zip   1.83KB   18 downloads

[Zauberberg]

Barbara,

Thank you for submitting the results. Now, we need to confirm the following: are these the results from Hysys blowdown simulations, or from your manual calculation work? My guess is that these are from Hysys, so we need your calculation results as well - at least those for the vapor phase (both cases - fire and cold case).

We should be having two sets of tables - one from Hysys, and the other one containing your calculation results, in order to make certain conclusions and to proceed further.

By the way, do you notice that the results are quite similar (with respect to final and minimum temperatures) for both cases, by using both methods? Your initial question was related to having very much different temperatures depending on the chosen U-value calculation method.

[barbara_s]

- yes when I simulated the case using U-updated and U-fixed I found more differentes results... If I find the old simulation I post.

- but I have also one other question: when I have to use the U-fixed and when U-updated, exite a criteria?
Or each time that I have a case I have to calculate the U values?

[Zauberberg]

In order to have that question answered, we'll need to complete the calculation work (your action item), and then to re-run Hysys models with your calculated values used as fixed U-values.

[barbara_s]

In order to have that question answered, we'll need to complete the calculation work (your action item), and then to re-run Hysys models with your calculated values used as fixed U-values.

thanks for your help!
But I have already re-run my simulations...
I choised the U-fixed (with U-values calculated) and I reported the results on xls...
I don't know why the results if I use U-updated or U fixed are similar...
I have to do more simulation... I don't understand...

By the way...
Thanks for your help and for your patience...