The engineering task
A fixed-tubesheet shell-and-tube exchanger undergoes repeated startups, cleaning cycles and switching operations. Shell and tubes have different mean temperatures and thermal expansion. This creates axial forces in tubes, tubesheet and shell even at unchanged pressure.
The static tubesheet calculation must be extended by cyclic thermal states. Rapid temperature steps, unequal heat-transfer conditions and cases with only one side pressurised are particularly important. The load spectrum must contain realistic frequencies rather than nominal operation alone.
Required design data
- Tubesheet, shell and tube geometry
- Time-dependent temperatures on both sides
- Pressure combinations including one-side pressurisation
- Counts of startup, shutdown and cleaning cycles
Technical solution approach
Define thermal states
Determine steady and transient mean temperatures of shell and tubes for each operating phase.
Calculate static tubesheet cases
Apply pressure and differential thermal expansion in every relevant tubesheet combination.
Form axial forces and stress ranges
Difference tube, shell and tubesheet forces between cycle extremes.
Perform fatigue verification
Assess critical stress ranges against cycle count and detail fatigue resistance.
Optimise operation or construction
Compare heat-up rate, bypass, expansion joint or alternative construction for improved life.
Expected deliverables
Suitable SOL ALPHA modules
The modules form a technically plausible toolchain. Their final selection and sequence will be confirmed during the later calculation against the applicable code and project conditions.