1692x
000329
2011-05-02

Fired Heater

 

The heat exchanger has an outer diameter of approximately 18 ft and is approximately 75 ft high. The chimney, connected by a cone, has a diameter of 4.4 ft and is 123.6 ft high. The structure consists mainly of sheets that were reinforced by exterior steel cross-sections in the bottom area. The structure is provided with refractory lining on the inside, but this does not keep all the generated heat away from the steel. Therefore, the structure was designed for a calculation temperature of +149°F.

Use of dummy rigids in modeling

Stage brackets were connected to the chimney on two levels. However, since only the reinforcement plates on the chimney and not the brackets were to be designed, the bracket members were modeled as "dummy rigids". In RFEM, dummy rigids are rigid coupling members for which hinges and other member properties can be defined.

Stress, stability, and vibration analyses

In addition to the general stress analysis for the sheet metal skin subjected to compression and the structural steel sections, a stability analysis of the steel sections and the entire structure was carried out, among other things. For the extensive stability analyses, the RFEM add-on module RF-STABILITY was used to perform stability designs according to the eigenvalue method.
Since the object is located in seismic zone 1 and, according to the manufacturer's guideline, the fundamental vibration should lie outside a certain range, the RF-DYNAM module was used for the vibration analysis. With FE-BUCKLING, sufficient safety against buckling was verified for the sheet metal housing.



Project Specifications

Model data

Number of Nodes 3446
Number of Lines 3757
Number of Members 1647
Number of Surfaces 673
Number of Load Cases 11
Number of Load Combinations 9
Number of Result Combinations 14
Total Weight 97.453 tons
Dimensions 27.98 x 25.64 x 203.57 feet
Program Version 4.06.09

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