Atmospheric Crude Tower 1

In HYSYS change your assay basis to mass - liquid volume is the default.

I have the ASTM D86 assay data for that I need to enter data only on volume basis. HYSYS does not accept data on mass basis and I have the data for % mass recovered.

What version of HYSYS are you using? I have 3.1 and 2006 and both allow me to change the basis from either liquid volume, mass or mole. In the "Input Data" section there should be a drop down menu called "Assay Basis" - there you can select your basis.

I have a question, the assay data types we have in hysys are TBP, ASTM D86, ASTM D1160, ASTM D86-D1160, ASTM D2887, CHROMATOGRAPH and EFV. What if in the laboratory the crude is analysed using differt method i.e ASTM D7169. How do you input the results of this method in hysys??

In such case, you have to apply manual conversion of laboratory results from one method to another. I'm not sure about these, but I think you can find related information (or references) in "Elements of petroleum processing" by Jones, and "Petroleum refinery engineering" by Nelson.

I have a lot of experience in modeling CDU towers, and what I can recommend you is definitely NOT to use D86 results as model input. Standard crude assay should contain TBP distillation, density and viscosity curves - at least. This is your Oil Manager input.

Best regards,

If the atmospheric crude tower doesn't converge with the given specifications what are the main things to be focused upon to converge the column??

If model input is wrong (incorrect assay/blend characterization), converging the column is as bad as not running the model at all: simply you cannot rely on such results, and product yields/qualities will show there's something wrong with the simulation approach, regardless of the number of theoretical/actual plates and their efficiency. Ensure your input data are completely valid, and later you can tune them if necessary.

Afte this step, try to relax your model by specifying ranges of convergence parameters instead of fixed values, and later you can narrow these to a single value. Try to think as "distillation tower", structure your specifications in order to leave a place for the model to breathe. For example, do not specify flowrate and duty (delta T) for all pumparounds, leave at least one free. Do not overspecify side draws (by fixing tray temperature and product draw rate), and alway fix the tower top temperature. If you model the column as refluxed absorber template, you have to assume/predict overhead reflux rate as well.

Best of luck,

Dear Chemical13

What specification did you select on Monitoring tab in Hysys? For the first step, flow rate on each draw and pumparound and reflux flow would be proper to get converged, and then you can try to get products on draw-off, which meet property targets such as flash point, with adjusting those flow rates. You should remember that all the flows and properties will not be matched with your actual data and lab result but be made closely with them. Hopely you can get beautiful modeling as you want.

Best wishes..