How to simulate the stress calculation using springs for heat exchanger equipment?

Firstly: The use of springs for device support is an unconventional design; assuming the fluid inside the device is liquid, the weight of the device will differ significantly when it is filled with a medium versus when it is empty. As a result, since the load on the spring varies within a very narrow range, the device shakes up and down, becoming highly unstable. It is generally used only in very special circumstances (such as when the pipes are very large, and due to layout constraints, the device springs can be relied on to improve the stress conditions in the piping system). Before using this approach, multiple discussions are required for approval. In fact: For the springs of a device, it is sufficient to consider the weight of the device itself as well as that of the medium. Consider the stress conditions of the piping system and the overall stability a little more. Additionally: if the medium of the device is gas, it’s much easier to handle. Because the change in weight is very slight. For the load on the spring, simply consider the equipment’s own weight as well as the weight of the pipes distributed onto the equipment.

The springs of the equipment must take into account the weight of the equipment and the medium, the stress conditions on the piping system, as well as the overall stability

Reply to 2# llu85: Thank you for your answer. I would like to ask you two more questions: (1) The original reboiler had a displacement of 2 mm upward (as indicated on the equipment nameplate). After the modification, the length of the head section of this equipment has increased by 1700 mm, and its weight has increased by 700 kg; the current weight of the equipment is 9235 kg (including the weight of the water inside it). Does the statement that “the spring for the equipment can generally be determined based on the weight of the equipment itself and the medium it handles” mean that the TD spring can be selected by referring to these two values: the original displacement of 2 mm upward and the current weight of the equipment with water inside it, which is 9235 kg? (2) When calculating the stress in the pipes connected to the equipment outlets, can the equipment’s brackets be modeled as having a displacement of 2 mm upward instead of using ANC points? Looking forward to your advice!

1) I don’t know what medium is being used and what its density is when you are operating it inside. If considering water, the case without a medium should be taken into account. As for the displacement, I can’t say anything without the piping diagram. 2) Simply include the equipment in the stress analysis as well. (Both anc and displacement serve the same purpose; they are both fixed supports, but in reality they are spring supports.) So there must be some distortion. In this way, the effect of your choice of spring will not be reflected in the calculation results.)

This post was last edited by eddiedong on 2011-6-27 at 22:43. Due to process requirements, the pipeline connection between the reboiler and the tower should be as short as possible; therefore, the pipe ends are usually connected directly to each other, resulting in little flexibility in the pipeline itself； Moreover, the temperature of the reboiler is not necessarily the same as the temperature of the tower wall, the support elevation of the reboiler is not necessarily the same as that of the tower, and the material of the reboiler is not necessarily the same as that of the tower. All of the above reasons mean that spring support is generally used for supporting reboilers (except for reboilers attached to towers); unless stress calculations show that fixed support would not cause significant loads on the pipe ends. During calculation, the unit material density of the simulated reboiler is set to 0, and the density of the fluid is also set to 0; instead, the operating weight and dead weight of the reboiler are applied to the units of the simulated reboiler as concentrated loads. As for the supports of the reboiler, a detailed simulation is required: starting from the support elevation, rigid elements are inserted to simulate each bracket, with a spring added at one end of these rigid elements. Generally, the shell of a reboiler is equipped with a corrugation to absorb the expansion difference between the tube side and the shell side. This section of the reboiler should be simulated based on the tube side material and temperature. Due to the difference between the empty weight and the operating weight of the reboiler, spring support will result in significant loads on the pipe ends, requiring verification by the equipment specialist or the manufacturer. The filling weight indicated on the equipment diagram is not useful for your calculations; what you need is the operating weight of the equipment, which is (the equipment’s empty weight + the weight of the materials). If you’re interested in doing the calculation, leave an email address and I’ll send you a previous example for reference.

Reply to 6# eddiedong: Could you send me one or two examples like this for reference? I’m about to simulate this thing; it’s my first time dealing with it. Thank you

Reply to 6# eddiedong: I forgot to send it to your email, sorry. chgxfm@163.com. Thank you

Reply to 6# eddiedong: Thank you for your guidance; I really need examples to refer to. My email address is xuaiqin325@163.com. Many thanks! ! !

Actually, in the past, for configurations where a reboiler is directly connected to a tower, it was simply mounted on the tower without any load-bearing or spring supports. It has been running for so many years with few problems.

Attached tower reboiler? Since supports are installed on the tower to hold the reboiler, it is possible to ensure that the reboiler and the tower expand synchronously, eliminating the need for spring supports. We affectionately call it a “BB phone”: lol