3 replies to this topic

[Lyne]

Hello everyone,
According to NFPA 59A, the calculation of a cryogenic storage tank vacuum breaker should consider the combined effect of three sources:

-Withdrawal of liquid or vapor at the maximum rate

-Increase in barometric pressure

-Reduction in vapor space pressure due to filling with subcooled liquid


For the third case, how should the reduction caused by subcooled liquid filling be estimated? Any insights would be greatly appreciated.

[latexman]

To get a volume reduction RATE the heat transfer RATE between incoming subcooled liquid and vapor space has to be estimated. Whether the tank is top filled (spray?) or bottom filled makes a big difference.

[Lyne]

could you please give me an example of how to estimate it in practice? What kind of assumptions are usually taken? At the moment I don’t have data, just trying to understand the method and develop my excelsheet. I’m still missing property values or operating details

[latexman]

I have no personal examples.

Take a look at these:

https://www.phy.anl..../appendix 2.htm

https://asiaiga.org/...ated Jan 12.pdf

More at Google (estimating reliefs on cryogenic tanks).