4 replies to this topic

[mosa]

Sir,

What is the difference between BAL,ADJ and DATABOOK operation in HYSYS and where to use each of them in what circumstances.If you explain me with examples it is appreciated.
You expert advise is highly appreciated.

Regards
momsal

[Srikrishna Chaitanya]

Dear Momsal ,

The adjust operation dosen’t not exist physically, its function is to vary the value of one stream variable (independent variable) to meet a required value or specification in another stream ( dependent variable). It’s some thing like manipulating one variable to adjust the value of another variable in another stream, for example consider a distillation column you can adjust the temperature of feed to distillation column to vary the flow rate of distillate from the column, this can be done by Adjust operation In this target variable is the variable that you want to meet specification (distillate flow rate) and Adjust variable is the variable that you can adjust (feed temperature)

Balance operation also doesn’t exist physically, its primary purpose is to make overall Material And energy Balance .you have to connect all the streams entering the process and leaving , you can specify the type of balance .

Data book is very useful tool, you can plot some variables see performance graphically, make tables, recording data for various operating conditions, monitoring key variables in the process etc.
All this basic information you can find in HYSYS help or Documentation that is available in Aspentech Website, but to access that documentation in Aspentech website you must be a licensed user, this is the website
http://support.aspentech.com/

Regards,
Satish

[mosa]

In databook operation, i changed a feed composition of distillation coulmn which is an idependednt variable whcih i have fixed and i selected other dependednt variables like tower bottom composition, tower top composition, reboiler load, however in selection box to select ind/dep variable it is checkboxes are inactive.Now the question arises how do i know which are dependednt and which are independent with respect to distillation tower.

And also kindly tell me for the given design reboiler duty and varying feed composition, i want to see the tower bottom composition results for the fixed reboiler duty.Could u pl tell me how to work it out and also how t get the steam flow to the reboiler?

Thank you

[Padmakar Katre]

As per my experience in Hysys we can not change the compositions of the streams which we have defined despite these are the independent variables ( independent variables are those which are user deifned) I am not sure but the reason is we can not change the compostions of the streams if the composition input basis is either mol fract or mass fraction.
One thing you can do is just check by defining the compositions on the basis of molar or mass flow i.e. give molar or mass flows of the individiual comonenets in composition tab and then insert these variables in the databook and check as independent variable in case studies but I am doubtful. Let me know your experience even I will check and will share my experience.
the best way to know the independent variables and dependent variables perform the following operiations in your simulation PFD and you will come to which condition or parameter is user defined and which is calculated by Hysys.
Shift + T = Temperatures of all streams will be displayed
Shift + P = Pressures of all streams will be displayed
Shift + M = Mass flows of all streams will be displayed
Shift + F = Molar Flows of all streams will be displayed
Shift +N = Names of all streams will be displayed

Note- The condition which has * before the numerical value it is said to be the user deifined means independent variable

[joerd]

Mosa,

As Padmakar said, you cannot change the composition of a stream via the Databook. However, if you want to do a case study you can define multiple streams with the compositions that you want to investigate, and then use a mixer with all of these streams as feeds. The outlet stream of the mixer becomes your feed stream for the column. Now you can, in the databook, use the molar flow of each of the composition streams as independent variable, and change the composition of the feed stream by setting the molar flow of one of the streams to the desired feed flow rate, and the others to zero.
By extension, you can define a stream for each one of your components, and change composition by setting the molar flows of the "component streams."
Hope this is clear,