Vacuum chamber vent nitrogen circuit 1

[Mordiyo]

Hello, hope you can give me some orientation about this problem.

I have to do the basic engineering for a nitrogen venting system for a pretty big vacuum chamber (one of those made to test satellites and space devices).
The organization who wants it installed alredy has one functioning, but unfortunately it's pretty far away, so i can't just go and check the facilities myself, but i can ask for some info.

The chamber is about 50 m3, and the venting sholud be made in a short period of time (first unknown quantity, how much is fast and how much is too fast??) by inserting nitrogen, which is alredy available in a liquid nitrogen tank.

I think the way to go would be to take nitrogen gas from the top of the tank, then running it through a heat exchanger or a similar device, then through a regulating valve (i really dont know what kind and if there is anything rated for such big flow)then a spherical valve, a high vaccum blade valve and at last a diffuser to avoid damage to the tested elements

Does this circuit make sense? the regulating valve is intended to be the only one to affect the flow, but i have very little idea what kind of valve i should go for, or if there is a vavle that can give this amount of flow (expecting about 5 Nm3/min), preferably one without closed loop control.

Well, that's quite it, i hope one of you can give me some ideas

Thanks

 

[Compositepro]

You don't want to draw vapor from the top of the LN2 tank. The head space is variable and you will quickly lose pressure in this tank. You draw liquid though a vaporizer. In your case, since you know pretty precisely how much N2 you need to vent the vacuum chamber, you could size a compressed N2 vessel to be a just the right size and pressure so that it can supply all the N2 vapor needed for the venting event. This way the temperature would always be pretty close to room temp. Trying to control the temperature of a large surge flow of vaporized LN2 is not easy.