Steam Hammer Issue in Reboilers/Condensate

[AlyMac]

Recently when starting up our plant, we experienced some hammering in one of our condensate systems. After having a few discussions, this issue has come up in the past and a few ideas have been attempted but the problem seems to continue. Basic idea of the process I'm referring to: Vacuum column with two identical vertical thermo-syphon reboilers. Each reboiler has its own condensate line, but they share the same condensate pot. The condensate lines are horizontal and discharge to the top of the condensate pot (3 elbows in each line between the reboiler and condensate pot), which sits about 2-3 feet below the bottom of the reboiler. I was outside when it started hammering, and it appeared to be hammering in just one of the condensate lines. Some theory is that when we start up, we don’t have enough heavy material in the tower, and the hot condensate is vaporizing and condensing in the line…which causes the hammering. The level in the condensate pot is locally controlled on flow control. In the past, the level transmitter was re-ranged in order to keep the condensate pot full, but that has not seemed to work. Any suggestions on what else could be causing the hammering? This is my first post, so let me know if I need to add more detail.

 

[saleda]

you should first run your system without vacuum let it run in reflux for some time then apply vacuum , problem will be resolved.

 

[sshep]

Hammer problems like this are almost always due to vapor being collapsed by contact with subcooled condensate. The rapid vapor collapse pulls vaccum and causes liquid slugs to accelerate followed by sudden stop which you hear as a hammer.

What is your process temperature? How is the reboiler controlled? Chest pressure? Drawing?

 

[katmar]

Check how horizontal the horizontal condensate lines really are. Particularly the noisy one. If condensate flashes from the reboiler into the condensate line (at a lower pressure) and then the flash steam comes into contact with cold condensate at a low point in the "horizontal" line it will rapidly condense and cause hammer as described by sshep.

If you can slope the lines from the reboiler down to the condensate pot to make them self draining that would be even better.

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