- Three 250MW systems generating power and process steam for a European aluminium production plant
Problem:
- Severe cracking at welds between the boiler casing and the integral steam drum, leading to loss of exhaust gas with subsequent environmental problems and high maintenance costs
Approach:
- Design review and root cause analysis
- Transient and steady state thermal stress calculations
- Re-design study, including heat conduction calculations to define the type and thickness of insulation required on both the inside and outside of the boiler
Benefits:
- Root cause identified as severe temperature difference between steam drum and boiler casing during normal steady state operation.
- Start up and shut down transients confirmed not to be the cause of the temperature differentials
- An insulation blanket, attached to the inside of the boiler casing to eliminate the severe temperature differentials, designed and fitted
- Environmental issues eliminated
- High cost of regular strip-downs and re-welding eliminated
- Small increase in efficiency and available process steam