Alkylation acid header

[Nagara]

Hi. I´m the process engineer of an Alkylation HF unit. As many units of this type, we have an acid header, that collects gas streams that may contain HF, and a regular Header. API recommends that a purge gas is provided to minimize stagnant pockets, and corrosive atmosphere in these headers. There is no recommendation for minimum flow/velocity of this purge gas. Does anyone have any criteria regarding minimal flow of this stream??

Thanks,Nagara

 

[boredinref]

Nagara, there's no criteria available for that. What most people do is to take the purge gas from the refinery N2 header, for example, and connect it to the alky acid header using a 2" line, or something like that. Since you know the header pressure, you'll be able to estimate how much gas is being used. The important thing here is to ensure there's something moving in the header so HF doesn't get stagnant and cause corroison. Good luck.