5 replies to this topic

[dragon_warrior]

ALL TEMPERATURES IN DEGREE CELSIUS, PRESSURE IN kgf/cm^2
Steam enters the shell side of a H.E. at 160 deg C;P=4kgf/cm2 and is condensed and subcooled to 90 deg C.
Process water is in tube side,entering at 40 deg C, and is heated to 80 deg C.
Shell:one-pass, 625mm I.D
Tubes:192 U-tubes, of 20 mm O.D, 2-pass,6000mm length)straight section)
This HE is over designed, hence a Level of around 80% condensate is maintained in the exchanger using a control valve and a LT.

However it has been observed that hammering occurs in the condensate line at these operating conditions. What could be the possible reasons for it and possible remedies for the same?

[Art Montemayor]

Is this a chemical engineering homework problem or a quiz problem given as an assignment?

If it is, do you want our members to work up the correct answer, give it to you so that you can hand it in for credit without studying, working for it, or earning it?

Please answer. Otherwise, I'll be forced to delete the post as just a futile exercise in avoiding study or work.

[dragon_warrior]

Well no it is not a HW problem. It is a problem I came across surfing online. I actually solved it myself, and found that the heat exchanger is aptly designed, and there is no problem with it.
My basic question is what could be the possible causes of hammering in such a scenario, if the problem is not with HE.
The only reason i gave the operating conditions was so that if anyone was interested in solving may do so.
So let me rephrase the question:
What could be the possible causes of hammering in the condensate line of a vertical condenser, if the problem is not with heat exchanger or the steam trap?

Also I wanted to know if the condensate line pressure drop could be a reason for hammering?

[breizh]

Hi ,

Have a look at this paper , it may help you .

Breizh

[kkala]

1. Interesting attachment by breizh explains cases of water hammer in steam and condensate lines. Probably it should be pointed out that condensate systems result in two phase flow. Water hammer is (most of the cases) due to entrained liquid phase, when it changes direction (like in wet steam). So it may be more aggressive in (α) slug flow (β) stratified flow (γ) annular flow (decreasing effect), while it may not occur in mist flow.
2. Lines can have rather unsteady liquid flow (e.g. collected in pockets, then ejected) making the problem worse. This can occur in the liquid hold up of vertical lines too.
3. Steam trap letting steam escape can influence flow pattern, hence water hammering; but it operates well in this case.
4. According to a practice, condensate lines are sized for a velocity of 1-2 ft/s, considering all condensate as liquid (no flashing). Check first condensate line diameter according to this criterion, though is is not expected to assure no hammering.

Edited by kkala, 08 June 2011 - 02:08 PM.

[breizh]

Hi ,
Regarding water hammer , this link is very useful :

http://www.kirsner.o...rticlesAlt.html

Breizh