10 replies to this topic

[harsh]

Hello 

First of all thank you for keeping this web-site active and up to date. I always learn new things when I visit, almost daily. 

 

Recently I have started simulating storage sphere in HYSYS. Inside the spherical tank, there is cylindrical can at the center with height less than diameter of sphere. Can is welded at the the base of the sphere and open at the top.  Properties of Liquid inside the cylinder is different than that of outside of cylinder. Cylinder has one liquid inlet and one liquid outlet. Outside of cylinder has one liquid inlet and one liquid out let. Both share common vapor outlet for at the top of the sphere. Two PSVs are at the top for protection

Attached file shows the dimensions.

 

Is there any way to size this sphere in ASPEN HYSYS V 8.0. I am referring to Customization guide by Aspen HYSYS and planning to utilize extensibility option. Is that the right way to go?

 

Please share your comments.

 

Thank You

 

Harshavardhan

Attached Files

•  sphere geometry.png   26.33KB   4 downloads

[Bobby Strain]

Why would you need to do that? The solution is one of applying geometry. Search the site for sphere volume.

 

Bobby

[samayaraj]

Do you want to calculate the partial volume of two liquids in both the vessels?

[breizh]

harsh ,

 

Let you consider the xcelsheet attached , it may help you, expecting I understood your query .

 

(revision after correction of typos and for better reading )

 

Breizh

Edited by breizh, 01 January 2016 - 09:20 AM.

[harsh]

Thank you for your comments

Bobby: I would like to carry out dynamic simulation in Hysys

Smayaraj: I have calculated the partial volume in the sphere.

Breizh: Attached is the excel sheet for volume available around the cylinder till the height 51.06 ft from bottom of the sphere

 

I would like to include this geometry into hysys for dynamic simulation.

Any thoughts on this?

 

Thank You

 

 

 

Attached Files

•  harsh.xlsx   124.09KB   34 downloads

[breizh]

harsh ,

Can you share some info about the materials stored , for me to understand the design of the equipment ? Should I understand that the top of the cylinder is open with the risk of contamination from both streams ,if I consider your calculation ?

 

Note : regarding Dynamic simulation , what is the purpose ?

 

Thanks for sharing

Breizh

Edited by breizh, 02 January 2016 - 04:45 AM.

[harsh]

Breizh

 

Sphere is meant to store different grades of NGL. Grade inside of cylinder should not mix with grade outside of cylinder.

I would like to perform dynamic simulation to understand scenarios during which the pressure will change in the sphere. There are various reasons for pressure to change. (1) Change in temperature (due to process or ambient) of both grade NGL, (2) Change in compositions and thereby physical properties (density, viscosity etc) of NGL grade (3) Emergency situations (4) changes in inlet (or outlet) flow-rate at different holdup scenarios

[serra]

I agree with Breizh,
you can solve these problems with Excel or similar tools (Matlab, Mathcad etc.)

providing you know fluid properties and phase equilibria,  

 

for those I adopt a process library (in my case Prode Properties)

but you can use a simulator as well...

 

note that you should include heat transfer and additional contributes...

Edited by serra, 04 January 2016 - 03:15 AM.

[Dacs]

In my view, implementing this in Hysys will be a challenge since it implies that you want to study the behavior of this sphere, in which it should consider:

1. V-L equilibrium between two liquid phases (grades of NGL) and the common vapor space (side comment: given enough time, should we expect both grades to become the same, composition wise?)

2. Heat transfer between ambient and sphere, common vapor and two liquids, and also between two liquids via this cylindrical baffle

[harsh]

Hello Dacs

It is little bit tricky to get the sizing in hysys. And there will not be any validation to check if the simulation is giving the correct results.

The two NGL grades will never mix. NGL outside of the cylinder is lighter than NGL inside the cylinder. The heavy NGL inside the cylinder will not contribute much towards the vapor as it has lower vapor pressure.

 

I am planning to implement following thinking:

 

1.  Overall volume of entire sphere (V) - Volume of the Cylinder [C] = Volume available for the lighter NGL (V_ngl).

2. This V_NGL can be considered as a sphere containing lighter NGL

3. The heat exchange between two grades of NGL through cylindrical wall can be considered as a energy stream/or duty. This duty can be varied dynamically to mimic heat exchanged at different temperature and levels of the heavy NGL inside the cylinder.

 

Your comments are appreciated.

 

Thank you

Edited by harsh, 15 January 2016 - 04:58 PM.

[serra]

if it is for a real project how do you expect to validate results ?

You would need to solve mass & heat balance by hand or arrange something with Excel or similar tools,

(see my previous post)