Steam flow rate (loss) through top of condensate tank 1

[engoz]

Hi there,
I have two questions here but the first and most important is I'm trying to find out the flow of steam from the top of a return condensate tank from a sugar mill pan area so I can work out the condenstae loss. The pressure in the water tank is 75kpa and their is an open 6 inch gate valve on top of the tank which lets out the steam from the water.
The second is I want to put some sort of steam trap on this 6 inch outlet pipe to save this condensate loss. Is this a possibility for this application?

Thanks in advance,

 

[TBP]

Use the line size and differential pressure between the tank and atmosphere to calculate the steam flow.

You might try using a heat exchanger on the vent, if you have a use for the recovered heat. I think you'll find the steam flow isn't as much as it appears. In any event, it'll all come down to economics.

Be VERY careful if you're considering installing something like a trap on this vent line. All a trap is, is an automatic valve. You could pressurize this tank to dangerous levels, or back condensate up your process due to increased back-pressure, causing problems there. The tank will need to be vented for the condensate pumps to work.

 

[engoz]

Thanks TBP,
Have you also got an actual formula for working out the steam flow?

 

[TBP]

Two thin publications I find very useful are "Technical Paper No. 410" by Crane, and "Hook-Ups" by Spirax Sarco.

In the Crane literature, look in chapter 3, page 22. Another approach is to use a table in "Hook-Ups", which shows the percentage of flash steam from given pressures to atmospheric. (In the 11th edition, the table is on page 41.) The table shows 2.9% of condensate at 10 PSIG will flash to steam when dropped to atmospheric pressure.