a 70,000-lb heat exchanger system required to withstand wind, seismic, and gravity loads
A contract engineering firm designing a large-scale industrial heat exchanger system for a plant in Mailliao, Taiwan needed a critical analysis performed: precisely how much load each of the sixteen structural support points would carry under the full range of operating conditions.
The challenge wasn’t straightforward. Because the system is statically indeterminate — meaning the loads can’t be solved by simple equilibrium equations alone — the support reactions can’t be determined by hand calculations. A finite element model was the only path to a reliable answer.
What We Did
O’Donnell Consulting Engineers built a finite element model of the entire heat exchanger system, including the waste gas inlet ductwork, the waste gas outlet ductwork, and the heat exchanger vessel itself. The three sections were modeled as solid bodies with densities calibrated to match their actual weights:
- Waste gas inlet section: 11,000 lbs
- Waste gas outlet section: 7,000 lbs
- Heat exchanger: 52,000 lbs
Components not explicitly modeled — expansion joints, tubes, tubesheets, nozzles, and miscellaneous hardware — had their weight incorporated into the overall assembly weight to ensure accurate load distribution.
The heat exchanger system was modeled as a rigid body, consistent with the high relative stiffness of its structural components. Rigid massless beam elements connected the system to all sixteen support locations, enabling accurate calculation of the reaction forces at each point.<.span>
Load Cases Evaluated
We determined the resultant support forces for three governing load conditions: wind, seismic, and gravity. These results gave the structural steel design team the verified input loads needed to confirm the adequacy of the supporting framework.
