2 replies to this topic

[NewEng2030]

Hi everyone,

I’m designing an inlet separator (60 MMSCFD natural gas, 70 bar, 25°C) for a university LNG project. This is my first time using Aspen HYSYS.

Honestly, I’m really lost.

Before I even start the simulation:

• What are the main things I need to define first?
• Which fluid package should I use for high-pressure natural gas?
• Should I run a flash calculation first?
• What design assumptions do I need (K-value, droplet size, etc.)?
• How do I know if I should consider slugging?

Also… how do I even start sizing the inlet separator?
What is the first calculation I should do?

I feel confused about the correct order of steps.

Edited by NewEng2030, 12 February 2026 - 09:16 PM.

[Pilesar]

Is this an inlet separator before a compressor? Or something else? For a student, I think the main criteria will be establishing your sources of information. You could guess at a design and be correct, but that would not teach you anything. Build your design based on methods and guidelines that other engineers have used that are documented and widely accepted. For vapor-liquid separators, there are surprisingly many 'standard' ways to arrive at a design. Some are 'quick and dirty' and others evaluate many properties and variables. In my opinion, separators in the real world are difficult to evaluate rigorously so no one realizes when designs are less-than-optimum. After researching and evaluating many 'standard methods' for separator design, I settled on using the methods found in the GPSA Technical Data Book and recommend that approach. This reference became my go-to resource for so many unit ops. 
 

[breizh]

Hi,

You may not need Aspen for this type of work.

Consider the link attached:

CheCalc ‐ Equipment

 

GPSA is definitely the right resource.

Breizh

Attached Files

•  TWO Phase Separator Design Guide By Manish Shah.pdf   2.59MB   2 downloads
•  Gas-liquid separator Fundamentals.pdf   296.93KB   2 downloads
•  Gas_Liquid_Separation_Technology.pdf   2.95MB   2 downloads