Someone else may offer advice here, but you may also want to ask
at Jacques' new group,
<a href="http://groups.yahoo.com/group/centrifugal_pumps">http://groups.yahoo.com/group/centrifugal_pumps</a>
Since that group is just starting out, there are not as many members as us, but they are more pump-focussed and may be able to better help with cavitation issues.
Paul
> Hi All
>
> Some time ago, I reported unstable conditions in a condensate
pipe that fed
> into a flash tank. The problem was simply a large pressure drop
across the
> valve, which caused bubbles in the pipe. These bubbles
immediately collapsed
> creating the instability.
> The problem was solved by relocating the valve right next to the
flash tank,
> hence the bubbles had little opportunity to form inside the
pipe, but were
> expanded into the large flash tank. This solution worked
perfectly. My
> thanks to Phil Thompson, who supported this remedy.
>
> In another area, a "similar" problem appeared due to plant
modifications.
> We're gravity feeding water into a contact heater that operates
under
> sub-atmospheric pressure 0.5 bara, (7.25 psia).
> When the control valve begins to open, violent banging and
clanking takes
> place for a few seconds, violent enough to cause damage to welds
along the
> pipe.
> With the same problematic symptoms as in the previous example,
we elected to
> apply the same "solution". We moved the control valve 5 meters
downstream
> and relocated it 0.5 meters from the contact heater. The results
were not as
> dramatic, there is still some hammering, but not as severe as
before.
>
> Is 0.5 met proximity to the contact heat exchanger
sufficient?(The piping is
> 150 mm or 6")
> Given the limitation of my description of the problem, is anyone
able to
> suggest areas that we may have overlooked, or suggest another
theory that we
> could examine?
>
> Thanks
> Ahmed Vawda
> Process Engineer
> Al Khaleej Sugar - Dubai
Received on Sat Sep 15 18:04:00 2001
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