7 replies to this topic

[Li Zhenhua]

Hi, everyone, I am a student who doing a project about flue gas injection modelling. I wanna know the pressure when the flue gas comes out from a typical power plant. I search it for so long. So I hope somebody can help me. Thank you so much.

[Zauberberg]

Li,

Flue/stack gas pressure is always slightly higher than atmospheric pressure, and how much higher depends on the point of measurement. Difference between flue gas and ambient pressure is in the order of mmH2O.

Not sure how accurate figure you may need for your calculations, but basically considering ambient pressure + 10mmH2O should be good enough for almost everything.

[Li Zhenhua]

Hi, Zauberberg.

Thank you so much for your information.

But just one more basic question:

You said 10 mm H2O.
1 atmosphere = 1033.227 cm H2O; so is 10 mm H2O = 10 mm H2O / 10332.27 mm H2O = 0.0008678 atm ?

[Zauberberg]

10mm H2O gauge pressure (atmospheric pressure + 10 mmH2O).

[pavanayi]

Li,
Read slowly again what Zauberberg has written.
ambient pressure + 10 mm water equates to 10332+10 = 10342 mm water. It is not just 10mm water.
Also,
Do not fuss too much with such figures. 10mm water, as Zauberberg said is just to quantify 'slightly higher than atmospheric'.
For cases such as pressures in atm, anything beyond third decimal does not have any physical significance, neither you need it (0.0008678 is just a number)

Edited by pavanayi, 31 March 2011 - 08:18 AM.

[Li Zhenhua]

Hi, pavanayi

Thank you for your explanation.

[Li Zhenhua]

Hi, Zauberberg

Thank you so much for your time.

[Qalander (Chem)]

Hi, Zauberberg

Thank you so much for your time.

Hello/Good Morning Dear Li, Further to whatever is very precisely guided by my friend Zauberberg.
I request you to consider conceptually that

• there has to be a pressure drop to make the flow out of stack for any flue gas stream,
• therefore this mainly depends on the design values and
• same should be referred while simultaneously considering
• all modes and conditions of flue gas being ejected.

Hope this proves helpful in firmed-up designing of your waste heat recovery set-up research and development work.