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4

# Flue Gas Stack Modeling

3 replies to this topic
|

### #1 Maryam sheikhmohamad

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Posted 28 May 2023 - 06:47 AM

Hello all,

I hope you can help me out in a simple topic. I’m going to model a flue gas stack in aspen hysys to check heat transfer and I’m using pipe segments feature. The bottom of the stack is conic starting from diameter of 17’ and being reduced to 8’ in 70’ of height. After that stack is like a 8’ pipe. Any idea of how to include that conic section in pipe segment? Or any idea of an alternative way of modeling a stack?

Thanks
Maryam

### #2 Pilesar

Pilesar

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Posted 28 May 2023 - 07:28 AM

This book excerpt may be a useful reference:  https://tinyurl.com/chimneycalcs

### #3 breizh

breizh

Gold Member

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Posted 28 May 2023 - 06:42 PM

hi,

Not knowing how it works with Aspen, I was thinking to use the same lateral surface for heat transfer for tween a truncated cone and a cylinder of diameter 8 '.

If my calculation is correct, I get equivalent length of 109 ' for a 8' Diameter.

Hope this is helping you.

Breizh

### #4 2000Miles

2000Miles

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Posted 31 May 2023 - 01:44 PM

To model a flue gas stack in Aspen HYSYS with a conical section, you can use the Pipe Segment feature and specify the diameter changes along the height of the stack. Here's how you can include the conical section:

Open Aspen HYSYS and create a new case or open an existing one.
In the simulation environment, go to the Flowsheet tab.
From the Object Palette on the left, drag and drop a Pipe Segment onto the flowsheet.
Double-click on the Pipe Segment to open its properties.
In the Properties window, go to the Geometry tab.
Under the "Geometry Type" section, select "Variable Diameter" to allow changes in diameter.
Specify the starting diameter of the stack, which is 17' in your case. You can enter this value in the "Diameter" field.
Click on the "Add Point" button to add additional points that define the diameter changes along the stack's height.
For the conical section, add a point at the desired height and specify the diameter at that point. For example, you can add a point at 70' height and enter the diameter as 8'.
After adding the required points and diameters, click on "Apply" to save the changes.
Connect the Pipe Segment to the appropriate inlet and outlet streams in your process simulation.
Configure the rest of the properties, such as fluid composition, temperature, and pressure as needed.
Run the simulation to analyze the heat transfer and other relevant parameters.
By defining the diameter changes using the "Variable Diameter" option in the Pipe Segment, you can model the conical section of the stack. The stack will transition from the starting diameter to the specified diameter at the defined height.

Alternatively, if you prefer to model the stack as two separate sections (conical and cylindrical), you can use two Pipe Segments and connect them to represent the different sections of the stack. The first Pipe Segment would represent the conical section, and the second Pipe Segment would represent the cylindrical section.

Remember to provide appropriate inputs for the fluid, heat transfer coefficients, and any other relevant parameters to obtain accurate results in your analysis.

Hello all,

I hope you can help me out in a simple topic. I’m going to model a flue gas stack in aspen hysys to check heat transfer and I’m using pipe segments feature. The bottom of the stack is conic starting from diameter of 17’ and being reduced to 8’ in 70’ of height. After that stack is like a 8’ pipe. Any idea of how to include that conic section in pipe segment? Or any idea of an alternative way of modeling a stack?

Thanks
Maryam