7 replies to this topic

[daraj]

for a 12-bed PSA making high purity ydrogen, what is te typical tail gas pressure and temperature? I dont find temperature mentioned anywhere. I believe the product hydrogen comes out at 0.5 bar or less tan feed pressure and at temp close to 50C(correct if wrong)

[PingPong]

For design purposes:

 

Typical tail gas temperature is about 10 ^oC lower than PSA feed gas and tail gas pressure downstream buffer vessel and filter is typically 0.35 barg (5 psig). That is to have about 0.3 barg pressure at burner.

 

Typical hydrogen product temperature is about the same as PSA feed gas, and hydrogen product pressure ex PSA is typically 0.6 bar lower than PSA feed gas.

Note however that there normally is a pressure control valve between PSA and battery limit (BL), so PSA inlet pressure is typically 1 bar higher than the hydrogen BL pressure.

[daraj]

Thanks Pingpong

[daraj]

Pingpong, wanted to confirm this again. considering hot n2 is usually used for bed regen, any reason as to why PSA tail gas should be 10c lower than feed gas? suppose if my feed gas is coming in at 30C say, then tail gas will leave at 20c? (whic is lower than cooling water utility)?

[PingPong]

There is no hot N2 during normal operation.

 

The tailgas is lowered in pressure and will experience JT cooling.

 

The licensor designs that I have seen through the years indicate a roughly 10 ^oC lower temperature in the heat and mass balance, so that's what I mentioned before.

[daraj]

ok,is a presure of 0.3-0.5barg(or 1.3-1.5 bara) reasonable for tail gas?

[PingPong]

As I already wrote before: tail gas pressure downstream buffer vessel and filter is typically 0.35 barg (5 psig). That is to have about 0.3 barg pressure at burner.

[gegio1960]

there are situations where a higher h2 recovery is a must.

in these cases a rotary compressor is installed downstream of the tail gas mixing drum in order to minimize the tail gas pressure.

you can go down to 0.1 bara increasing the h2 recovery by several points.

in other words the tail gas pressure is defined by the downstream system pressure.

Edited by gegio1960, 02 January 2022 - 04:56 AM.