Hammer in Reactor Dome Dimple Jacket
Hammer in Reactor Dome Dimple Jacket
(OP)
Hello,
We think our reactors are experiencing hammer in the dimple jacket that encompasses our reactor dome. The dome cooling liquid is treated water. Is there any considerations that might be helpful to preventing this hammering from occuring (less or more water flow into jacket)? My guess is that steam pockets might be forming in the jacket and cool water hitting the steam is causing the hammer.
Thanks.
We think our reactors are experiencing hammer in the dimple jacket that encompasses our reactor dome. The dome cooling liquid is treated water. Is there any considerations that might be helpful to preventing this hammering from occuring (less or more water flow into jacket)? My guess is that steam pockets might be forming in the jacket and cool water hitting the steam is causing the hammer.
Thanks.





RE: Hammer in Reactor Dome Dimple Jacket
Whats T in the shell? Whats T and P in the dome jacket? Is the controlling heat transfer coefficient on the shell or jacket side? Or is it the metal?
Has it always done this or just started? How long has it been in service? Has the flow changed?
Good luck,
Latexman
RE: Hammer in Reactor Dome Dimple Jacket
Would adding a backpressure valve on the outlet of the cooling water helpto decrease this hammer? Is this option because this would increase P in the jacket thus the water would have to reach a higher T to transform into vapor?
My though was to increase flow so the flow characteristics in the jacket so there would be no dead spots? Would this help?
THanks for the reply.
RE: Hammer in Reactor Dome Dimple Jacket
rmw
RE: Hammer in Reactor Dome Dimple Jacket
Jacket cooling water comes in about 70 degrees F. The temperature in the reactor is around 250 F. Pressure if I remember correctly is around 10 psig. Heat transfer coefficient is on the jacket side (I believe tube side then).
Thanks
RE: Hammer in Reactor Dome Dimple Jacket
Before you do increase the water flow, which would increase the cooling, however, you should check the process side in the dome to be sure that adding cooling water would not be detrimental to whatever is going on inside the 250 degree dome.
rmw
RE: Hammer in Reactor Dome Dimple Jacket
Thanks.
RE: Hammer in Reactor Dome Dimple Jacket
Two things to note:
If there are no baffles inside the dimple jacket then any bubbles that form will tend to rise to the highest point. Can you put the water outlet at this highest point so that any bubbles will be removed as soon as they form and they will not have a chance to join up and make large noisy bubbles?
Be careful of increasing flowrates or back pressure valves or anything else that will increase the pressure inside the jacket. Jacketed vessels fail a lot more frequently due to external (i.e. jacket) pressure than because of anything else. Check the allowable design pressure in the dimple jacket before you make any changes.
RE: Hammer in Reactor Dome Dimple Jacket
RE: Hammer in Reactor Dome Dimple Jacket
I have seen failures where the jacket still looks perfect from the outside, while the shell inside is destroyed. The outer shell of the jacket obviously has the pressure on its concave side, but for the vessel shell it is on the convex side.