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Exothermic Reactor Shut Down

Exothermic Reactor Shut Down

(OP)
We have a case in which when we cut off the inlet feed to an exothermic reactor (feed is gas) the temperature in the reactor still rises for a while. Given that we expect it almost immediately stops rising our first guess is that there is a delay with temperature sensors within the reactor. Any thoughts or similar experiences?

RE: Exothermic Reactor Shut Down

There is certainly a delay with most temp sensors. Some can be almost instantaneous but typical thermocouple wells and such can add 10s of seconds.

I'd also expect that if the reactor contents are rising and you kill the feed what feed is unreacted would still take a finite amount of time to react and would delay any temperature decline further.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Exothermic Reactor Shut Down

The accumulated un-reacted raw materials are reacting. That effect is probably larger than the temperature delays, but it depends on the chemistry.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

RE: Exothermic Reactor Shut Down

Reactor temp would not rise if you keep the reactor temp control coolant utility still running through the reactor ??

RE: Exothermic Reactor Shut Down

Look carefully at your chemistry, does the reaction go through multiple steps (even if very quickly)?
Considering that reaction rates are function of temp I am not surprised at this.
If you are aiming for better control it sounds like you need better modeling and a feed-forward control methodology.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Exothermic Reactor Shut Down

A temperature chart showing the phenomenon would be helpful.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

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