National Board NB-27 Questions

[hernanrmz]

Hello,

We are implementing the NB-27 A Guide for Blowoff Vessels in our Purge tanks desings, but I have a question for people who use this document.

For the calculation of the diameter of the vessel, you calculate first the requiered cross-sectional area (AR), using the mass flow rate of the fluid (m) (Eq. 13 page 10). This mass flow rate it is the mass flow of the two phase (denominate as "m" before in the document, in page 7) or it is the mass flow of the flashed steam "ms". In the example of the document they used the mass flow of the steam "ms" and they change the variable "m" to "ms" (page 165)

Another question is, there are some limitations in this document?. When I try to decrease the height, increasing the diameter there is a point where the height doesn't decrease anymore, and then start to increase.

Here you can find the document:

https://www.nationalboard.org/SiteDocuments/NB-27.pdf

Thanks in advance.

Best regards!