Multi Stage Restriction Orifce

[Sawsan311]

Dear All,

I would like to Enquire on when to decide to have a multi stage depressurization restriction orifice instead of one RO, is it mainly driven by the coefficient of discharge, beta ratio and the t/d mandating critical flow with the condition of not exceeding rho.v^3 noise criteria?

Thanks

 

[RVAmeche]

Critical flow, noise/vibration/cavitation, erosion/damage all play a role in the selection

 

[Sawsan311]

Thanks RVAmeche for your reply,

For the critical flow, can we say that due to the requirement of having sufficiently thick orifice for critical flow and considering the case of very high pressure drop, having an optimum a coefficient of discharge of 0.84 (as per Smith paper and Cummingham) (with a range of t/D between 1 to 7) is coming at the expense of small beta ratio (dorifice/dpipe) which means that the theoritical flow rate would be small for a single RO and hence a second stage RO is required to dispatch the inventory's number of moles at the desired rate /time).

Thanks

 

[hacksaw]

It's a bit more complicated than that. Pressures, fluid, temperatures, metallurgy being considered, as a minimum.

 

[casflo]

Usually the main criteria is to avoid cavitation dividing the required pressure drop in 2 or 3 stages.