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[Bodhisatya]

As a part of Front end purification in Air Separation Unit, a pair of adsorber (one online, other in Regn mode) is used to eliminate impurities that might act as a hindrance in Cryo temperatures.

While studying a macro enabled excel, stumbled across following calculated values during pressurisation step.
(Re-generated bed is pressurised by ramp opening a globe valve, injecting pressurise from the online bed)

(a) Pressurisation valve Cv
( Largest Cv allowed in pressurisation line.

Esteemed members throw some light on how to proceed.

Bodhisatya Das

[sgkim]

Hi, 

The pressurization valve opening shall not subject the other online bed to process upset by pressure fluctuation, then the size of the valve may be limited, while a suitable Cv value would be selected based on the differential pressures between the running and regenerating beds to minimize the time for pressurization.

 

The flow through the valve shall be determined by the typical method applied for orifice calculation.  As the velocity of air in the nozzle is limited by the sonic velocity, the pressurization process shall be divided by the critical (sonic) flow session and subsonic.  Total time required shall be summed for the two sessions.

 

~Stefano