Formula for vent diffuzer sizing

[markzu3]

I am looking at sizing a steam venting diffuser to dissipate steam from high pressure to atmospheric.

The diffuser will have a diameter of 24" with upstream pressure of 284 kpa. If we were to vent the steam through perforated holes (32mm) drilled into the 24" diffuser wall, how many holes do we need to drill, assuming the flow is chocked. Note that the end of the diffuser is capped. I need to find the correct formula - whether to use the folrmula in Perry (Perry's Chem Eng'g Hand Book 7th ed. Eqn 10-26 for critical flow conditions) or the one in Crane (eqaution 1-11). The problem is that there is a discrepancy of about 23% in the calculated flow between the two formulas.

 

[steam4]

markzu3,

What is your goal here.....noise reduction.....or moisture separation?

Dave

 

[markzu3]

The main pupose of the vent diffuser is noise reduction. It will vent the steam into a pit filled with rock. The diffuser is required to create some amount of pressure drop in order to maintain a given upstream pressure.

 

[steam4]

Another solution may be to use a unit made by Universal Silencer or QuietFlo.

 

[whippsa]

I'm looking for a way to dissipate steam (not pressure). Someone mentioned a rock pit?

I'm just a home owner--anyone have a suggestion? Need to change high efficiency furnace venting to front of house and wife worried about the appearance of the billowing steam in freezing weather (Michigan!).

It is an intake and an exhaust. One goes up and the other down. Those are not highly visible, just the billowing steam is a problem. The solution can't create backpressure or the furnace will shut off. It also can't be a haven for woodland creatures, or at least be easily cleaned out.