9 replies to this topic

[mosa]

Dear Hysis specialists,

I have converged SWS column, but i dont know how to get the steam flow to the SWS reboiler.Pl tell me the route to know where it is available.I could know only the duty of reboiler, but i want to kbow the steam flow and also where to give conditionss of steam.

Regards
mosa

[JoeWong]

I have converged SWS column, but i dont know how to get the steam flow to the SWS reboiler.Pl tell me the route to know where it is available.I could know only the duty of reboiler, but i want to kbow the steam flow and also where to give conditionss of steam.
Regards
mosa

Mosa,

You have duty of reboiler and you need to know the steam flow...

i) find out what are the steam type available for your reboiler heating...
ii) determine which steam type you will use. Ensure a good temperature approach (i.e. 10 degC) between steam temperature and process fluid temperature...
iii) then calculate the steam demand base on different in steam enthalpy and condensate enthalpy and the reboiler duty

I am not sure if this is the answer you are looking for...

[Zauberberg]

Mosa,

The duty of reboiler is the change of hot medium enthalpy (outlet-inlet). Assuming there is saturated steam at reboiler inlet and there is no condensate subcooling, calculation of required steam flowrate is straightforward.

Before doing this, you need to know what is the pressure of steam available for SWS reboiler. It is usually low pressure steam (since the tower operates at slightly higher pressure than atmospheric). If you are doing simulations of existing system, check what is the source (steam) pressure. If this is a theoretical/design model, I would go for higher temperature approach - at least 30-40C because this will save the reboiler surface area. So choose such steam pressure that will result in saturation temperature 40C higher than your sour water boiling temperature at tower bottoms conditions/pressure.

Also refer to an excellent article at SpiraxSarco website, "Steam Consumption of Heat Exchangers":
http://www.spiraxsar...-exchangers.asp

Regards,

[mosa]

I have converged SWS column, but i dont know how to get the steam flow to the SWS reboiler.Pl tell me the route to know where it is available.I could know only the duty of reboiler, but i want to kbow the steam flow and also where to give conditionss of steam.
Regards
mosa

Mosa,

You have duty of reboiler and you need to know the steam flow...

i) find out what are the steam type available for your reboiler heating...
ii) determine which steam type you will use. Ensure a good temperature approach (i.e. 10 degC) between steam temperature and process fluid temperature...
iii) then calculate the steam demand base on different in steam enthalpy and condensate enthalpy and the reboiler duty

I am not sure if this is the answer you are looking for...

[mosa]

Hi guys,

What i am looking for the solution through Hysis.How to get the steam flow in reboiler template in Hysys and in which window to enter the steam conditions.This will help me to see the effect on feed flow and feeed concentartion with respect to different steam flow at specified temp and press.Hence i want to know where and how to enter the steam conditions in Hysys ?

Regards
mosa

[Padmakar Katre]

Dear,
In the column envirnment delete the existing or defualt reboiler of the column and put the shell and tube heat exchanger and male the 4 connections as
For Process Side
1. Reboiler In
2. Boil-up
And for utility side
1. Steam In
2. Cond Out
This thing you can do in the column envirnment. Infact you can make the as built column model in the column envirnment for that try Custom Column Unit Opertation from your object pallet and and start with the Blank Flowsheet Option.
If further help you need please let me know.Waiting for your comment.

[mosa]

Dear,
In the column envirnment ,i deleted thew exisitng reboiler template and from the object palletet i selcted shell and tube template but unfortunately all other templates are accepting however shell and tube template is not acceptng as a pop up message is apperaing as Mod Hysim in/out and i dont know what is it ?.Could u pl tell me what is blank flow sheet option and how to get from menu bar ?

Regards
mosa

[Padmakar Katre]

Dear I thought that you would be able to do it. Anywyas the defualt method of the solver in the Hysys is Hysim inside-out.
Now follow the below steps to put the heat-exchanger in column envirnment.

1. Click On the column so column property view window will be displayed
2. In the Parameters page click on the Solver button.
3. And from the Solver Methods option select Modified-Hysim Inside-Out option from dropdown list.
And then enter into the Column Envirnment and put the Shell and Tube Heat Exchanger. I am sure this will solve your problem.

[JoeWong]

Hi guys,

What i am looking for the solution through Hysis.How to get the steam flow in reboiler template in Hysys and in which window to enter the steam conditions.This will help me to see the effect on feed flow and feeed concentartion with respect to different steam flow at specified temp and press.Hence i want to know where and how to enter the steam conditions in Hysys ?

Regards
mosa

If your interest is to ONLY to get the steam flow in reboiler and vary your steam flow...i don't think you need to goes through all the tedious step by interfering the existing column template.

Just create a dummy heater with steam as you feed. You can specify steam condition as you wish and varying the flow as you wish...Then equal the calculated power to your reboiler duty using SET operation...

[mosa]

Dear Padmakar,

I tried as per your advice, but i could not fit the reboiler in Column environment for the steam input.
Similarly i tried for the overhead condenser also.As you know in Simulation environment u get only Q values for reboiler and condenser.Hence in order to insert the heat exchanger and cooler.I first selected Modfied HysimIn/out and RUN the coulm and converged.Then i entered Column environment and deleted the reboiler and fit the shenn and tube template and in the COLUMN ENVIRONMENT , for tube side inlet i used ATTACH MODE to fit automatically for tube side input for the HE and shell side inlet outlet i defined steam inlet and outlet defining new conditions.For HE model, it takes HE calculation by column message appears and finally 'NOT SOLVED'.Same for condenser also.The indication Q for reboilerr and condesser is hanging seperately in the column environment as new HE temp[late is introduced.

Kindly provide me step by step method or any related articles, how to install reboiler and condeser specifying steam and water conditions and how to converge.

Similarly, i want to vary the column pressure in steps of 0.1 for 5 values and see the effect of bottom top temperature, off gas composition,flow and reboiler load.i tried in DATABOOK operations but all are apperaing as dependednt variable.

Similarly i have converged the column for the plant design conditions and adjusted to the plant operating conditions and is OK.

nOW I WANT TO INCREASE THE FEED in steps of say 10,10,10and see the flooding and downcomer back up% without giving input every time at the start of input value

Say if the column is flooding, how to insert the say packing and remove some trays and redo the simulation to see the effect on flooding and all other parametrs without affecting the orginal tray simulation.

In my tray simulation in the flooding details in the VIEW WARNING tab, it is highlighted HEADLOSS in downcomer is high although the flooding% is 78% which is less than recomended 85% and similarly downcomer back up is less than 50%.What does it mean, is it related to flooding

I am sorry to put everything , because this will help in other simulations also.Your help is highly appreciated.


Regards
mosa