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Furnace forced cooling

Furnace forced cooling

Furnace forced cooling

Dear all,

I have a confusion over this one issue - type of furnace cooling during emergency shutdown under low water condition.

When the water level is not visible in the gage glass, emergency shutdown of the boiler must be carried out, such as cutting off the burner, shut off feed pump, and close the main steam valve.

However, there are various opinions on types of cooling. Some said that the boiler must be forced cooling by continuing running the FD fan (or ID fan), some said the fan must be stopped to allow natural cooling. This is because thermal stress imposed by forced cooling could damage the boiler / alter the metallurgy.

Could you all fine gentlemen share your experience or your opinion on this issue? Thanks.

Warmest regards


RE: Furnace forced cooling

In my opinion it is best to leave the boiler to cool down by itself without any form of assistance such as leaving the FD fan operate, otherwise, tubes that were deformed during the low water condition may set and will not restore to their original length; then you will need to replace most of the tubes.

RE: Furnace forced cooling

I agree with chicopee; forced cooling should be avoided to prevent thermally shocking the tubes.

RE: Furnace forced cooling

Also agree with chicopee.

Additionally, there may be circumstances where it will be necessary to promptly drain a steam generator following such a trip to eliminate the possibility of severe differential expansion and "set" between the upper and lower portions of steam drums as the unit cools.


"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

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