ForumRe: Drum Filling
From: Jim Watts [764]
Date: Thursday, July 15, 2010
Time: 11:30:46 PM
Remote Name: 124.180.2.222
Comments
There are two reasons for topping up the drum when cooling after shutdown.One is to allow for shrinkage and prolong the time before the water needs to be topped up again so that the drum always has water in it.
Two is to ensure the total circumference of the drum is in contact with the water and will cool evenly from top to bottom.
The second only works if you continue to top up as the level tries to drop with shrinkage.
The 40 degree limit top to bottom is very important as it prevents the drum bending like a banana if the length of the top of the drum is longer than the bottom due to differential contraction.
It seems to me you basically know what to do.
The drum top to bottom must not be exceeded.
Keeping the water level high ensures this is ok.
The tubes are able to deal with much higher temperature changes hundreds per hour as they are thinner than the drum.
Bending the drum stresses the tubes most.
Of course the top to bottom is not the only rate to be respected as the drum inner to outer metal temperature difference is important also so your maximum cooling rate should not be exceeded either.
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