Pressure loss of gas from a 10" pipe to a stack

[CHEMTT]

If a gas passing through a 10" pipe has a pressure of 15 psig enters a stack that is 36" in diameter. The stack is 80 ft long and is open to the atmosphere. Would the gas as it enters the stack still have a pressure? or would the pressure at the base of the stack be atmospheric.

 

[katmar]

There are a few differences between your and my calculations. I had assumed isothermal compressible flow. Your temperatures drop quite a bit and this lowers your velocities (although there are sections where the temperature actually increases??). Is the line insulated? I don't think it is accurate enough to regard each sub-section as incompressible flow, even if they are as short as 5m each. The pressure drops are quite high and the compressible flow equations should be used.

I did not look too carefully but I was puzzled how you calculated your temperatures from the density changes. Maybe I just read that wrongly.

The number of bends in the spreadsheet does not correspond with the sketch. The sketch makes it look like the 10" flow goes through the branch of the tee, but the spreadsheet refers to the run.

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