Steam hammaring
Steam hammaring
(OP)
There is a steam heater where brine is being heated from 60 to 80 degree centrigrade.
There is a condensate trap designed for 0.5 kg/cm2 pressure drop.Due to low heat load the condensate pressure in the heater outlet remains near to zero.
At some time we observed that the condensate pressure sarts increasing and a steam hammering starts.
What can be the reason for this?
There is a condensate trap designed for 0.5 kg/cm2 pressure drop.Due to low heat load the condensate pressure in the heater outlet remains near to zero.
At some time we observed that the condensate pressure sarts increasing and a steam hammering starts.
What can be the reason for this?





RE: Steam hammaring
To eliminate hammering, the condensate from the heat exchanger needs to gravity drain to a vented condensate receiver. A vacuum breaker should also be installed on the steam side of the unit to allow drainage when the steam valve shuts completely.
If you can get a copy of Spirax Sarco's book "Hook-Ups", it has all of this information, and much more. It's a thin, soft cover publication that contains a huge amount of information, and I highly recommend it.
RE: Steam hammaring
Steven van Els
SAvanEls@cq-link.sr
RE: Steam hammaring
Another small "nit" to pick.
You are not experiencing "steam hammer" but rather hot water "flashing" to (some) steam (but mostly vapor) and "bubble collapse" when the steam goes back to liquid phase ("bang"). Steam hammer occurs much the same way liquid hammer does. Steam hammer does not involve phase changes - there is only steam in the line. Similarly, Liquid (e.g., water) hammer involves pipes FILLED with water - no air is involved. When a "slug" of water (e.g., condensate) is propelled down a steam pipe it is not "water hammer" but rather "slug flow". These are commonly confused issues.
I concur with TPB in his comments.
Regards, John.
RE: Steam hammaring
Ummm, I'm no fluid dynamics expert, and I might be wrong, but I thought that the pressure transient (the wave/pressure discontinuity that causes the hammer event) can be caused by several different things, one of which is in fact rapid phase change, e.g. rapid condensation/vapor collapse of steam in a water line? I once saw a 12" cogen main steam header jump clear out of its pipeway when they hit the header with warm water on unit startup. Pretty dramatic, to say the least... Broken anchors, guides, that sort of thing...
Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com