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Possibility of duel phase formation in H.P Steam super heater coil In primary reformer WHRS.

Posted: Wed Sep 02, 2020 6:45 am
by PKS1964
Dear All,
In Topsoe Ammonia plant, to recover waste heat from primary many coils (with different gas /liquid flow in side the tube) used to recover heat energy which help to reduce stake emission temperature.
In that system there is coil for HP Steam super heater named as E-203.
Some of the plant have two number of H.P Steam super heater coil and some of the plant have three number of Super heater coil.
Here I want to discuss that, Is there any observation of duel phase formation in side of H.P Super heater coil. How you have confirm this and what remedial action you have taken.

Regards
Prabhat

Re: Possibility of duel phase formation in H.P Steam super heater coil In primary reformer WHRS.

Posted: Wed Sep 02, 2020 7:01 am
by tjhilbers
Hi,
I am not sure what you mean by duel phase formation in a superheater coil. You can either make saturated or superheated steam upstream the superheater in the convection section of your reformer unit. When heated even further in this coil, you won't be able to get a two-phase flow, unless your actually cooling your steam under start-up/shutdown or by injecting too much desuperheating water. Two-phase flow is usually more critical for economizer coils where boiler feedwater is not supposed to reach its boiling point which results in a two-phase flow. If you meant two-phase flow as supercritical fluid, then you're operating at an unsually high pressure (> 220 bar) ;-)

Re: Possibility of duel phase formation in H.P Steam super heater coil In primary reformer WHRS.

Posted: Thu Sep 03, 2020 5:18 am
by MJA
A low temperature security is provided at BFW injection points to avoid two phase flow during any upset conditions. This security is available in between the two coils.