Case of shell-side vibration in heat exchanger – just occurred
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This post was last edited by wiseboy on 2015-12-22 at 12:31. Recently, a heat exchanger designed by a state-owned design institute experienced shell-side vibration when the load exceeded 50% during testing. The shell side is the liquid (water), while the tube side is the hot gas. Design tool: HTRI. I don’t know whether it’s a problem with improper use of the software or an issue with HTRI itself. The HTRI file was sent, but I didn’t look at it. The problem now is that it’s too late to do anything even after seeing it! How to address the de facto shock? Everyone, give some advice. I’ve thought of a few measures, from simple to complex, for discussion only: 1. I noticed that the heat exchanger is quite long, about 11 meters, but it has supports only at both ends; I suggest adding a support pillar in the middle. This is a simple and feasible solution ； 2. Removing half of the baffle plates will affect the heat exchange efficiency; however, if the design was originally quite generous, it might just be sufficient ；
It seems that the vibration in the shell side isn’t taken into account; it hasn’t been considered either. This is a reminder indeed. In that case, Option 1 might work, while Option 2 won’t solve the problem.
HTRI is used to calculate vibrations. As for where the problem lies, it is unknown.
May I ask the original poster: does shell-side vibration refer to vibration of the shell cylinder, rather than vibration of the heat exchange tubes?
Did the poster say it’s the vibration in the shell side due to fluid flow? That can only happen if there is a phase change in the liquid. What is the state at the shell-side outlet?
“\"That can only happen if there is a phase change in the liquid,\" – that’s a wrong theory; it’s a fundamental error. Is there a chance to systematically study equipment vibration theory if possible?
This post was last edited by wiseboy on 2015-12-22 20:18. The vibrations in heat exchangers generally include fluid-induced vibrations and tube bank vibrations. Theoretical calculations are very complex and difficult to determine accurately. HTRI has the capability to calculate vibrations, but it cannot do so accurately; generally, the design results are placed well away from the areas where such vibrations occur, but sometimes it is still impossible to avoid them. Heat exchanger master did not calculate vibrations because its developers had no confidence in existing vibration calculation theories and methods.
I’d like to hear from the experts on how to solve this problem
I just said that vibrations are more likely to occur when the email address changes; I didn’t say it’s a necessary condition. Vibrations can also occur in liquid conditions; this is due to the structural design, which causes the area where vibrations occur within the equipment itself to overlap with the area where vibrations arise as a result of fluid flow.
Could it be that water hammer is occurring?:)
1. Please send the HTRI calculation files so that we can examine the calculation data. 2. Why is the poster sure it’s shell-side vibration? Tube-side vibration could also be transmitted to the shell through the medium, but the handling methods for these two cases are different. 3. If it is determined that shell vibration is the issue, and it is not possible to change the conditions of the medium at present, then changing the natural frequency of the shell can be an approach to try. For example, 3.1. Adding intermediate supports to elongated shells can effectively increase one of the critical frequencies ； 3.2. Adding cross-bracing plates to the outer surface of the shell is equivalent to changing the wall thickness of the container, in order to increase the natural frequency, etc. 4. The principle of this treatment method is to change the natural vibration frequency of the shell in order to avoid resonance caused by the pulsation frequency of the medium