Simulation of Piping Operations (Compressible Gas Pipe , Pipe Segment, Valve, Relief Valve, Mixer, Tee) With Aspen Hysys.

1.      Compressible Gas Pipe <CGP> :

The compressible Gas Pipe (CGP) uses an algorithm that solves a vector system using the Two-Step Lax-Wendroff method with Boris & Book anti-diffusion.

∂U/∂t + ∂D/∂x = G

 The CGP unit operation primarily designed for transient calculations with streams calculations with streams. 

First we define our elements (inlet, outlet stream ).

Second we have to specify the profile of pipe (length-evaluation profile), here we specify:

• Length  of pipe
• Elavation change
• Cells o pipe  

Moreover, we can add more sections.

Third, we specify the Overall dimension of Pipe, specification of Overall dimension realized through two ways

• We pick the pipe schedule and the material from the schedule and material mentioned in the cases, after that we select the pipe size from the pipe size selections.

• Second way is to specify all parameters (Roughness, external diameter and internal diameter)

Fourth, we have to specify the ambient temperature and the Overall heat transfer coefficient (Overall HTC)

 

Finally we have the CGP converged, with calculating of Pressure drop, Max much number, Max Pressure and Max velocity 

2.      Pipe Segment :

The Pipe Segment is used to simulate a wide variety of piping situations ranging from single or multiphase plant piping with rigorous heat transfer estimation, to a large capacity looped pipeline problems.

First as usual, we have to define elements of our equipment (inlet , outlet streams and the energy stream) 

Second, we have to specify the Size of Pipe (Length, elevation charge, outer diameter, inner diameter and we pick our metal)

 

Third, we specify the heat transfer; The heat transfer can be specified by one of:

• Specify the heat loss  

• Specify the Overall Heat transfer coefficient (Overall HTC)

• Specify the sSegment heat transfer coefficient (Segment HTC)

• Estimate the heat transfer coefficient (Estimate HTC)  

• Specify the outlet temperature 

3.      Valve :

The main purpose of a valve is to control media flow through a system, Valve generally use in dynamic mode, in Steady state mode we can use Valve for decrease the outlet stream (like joule thomson valve).

First, we define the elements of operation (inlet, outlet stream).

 

Second, we have to specify the Delta P or we specify the outlet stream (must be low than the inlet stream).

      

1.      Relief Valve

Relieve valve is used to prevent dangerous situations occurring from pressure buildups in a system.

Relive valve used in Steady state mode like normal Valve (the valve is open) 

 

But in dynamic mode if the pressure of outlet stream is highest than the inlet the relieve valve will be close.

How do we can realize that?

First we define the inlet and outlet stream.

Second, we specify the set pressure and the full Open pressure.

Third, we specify the outlet stream pressure

 

After that we switch to the Dynamic mode 

If the pressure of outlet stream is low than the pressure of inlet stream the valve will be open. 

 

If the pressure of outlet stream is high than the pressure of inlet the valve will be close.

5.      Mixer :

The Mixer is used to combine two or more inlet streams produce a single outlet stream.

We define the inlet streams (at least two streams, and they must be converged) and we define the outlet stream.

Second, we pick “set outlet to lowest inlet” because we have difference pressures of inlet streams 

1.      Tee

The Tee operation splits one feed stream into multiple product streams with the same conditions and composition as the feed stream, and it used for simulating pipe tees and manifolds.

First, we define inlet stream and the outlet stream (at least two streams).

Second, we specify the splits or we specify the outlet flow directly.