Fired Heater Training Curriculum
Module 3 - Convection Section
Module from the Fired Heater Training Curriculum curriculum.
MODULE 3: CONVECTION SECTION · Extended Surface (Fin) Types
| Fin Type | Construction | Max Flue Gas Temp | Advantages | Limitations | Typical Application | Cost |
|---|---|---|---|---|---|---|
| Studded | Studs welded to tube OD | 1,600°F | Survives high T, fouling service | Lowest fin efficiency | Shield rows, high-T zones | Medium |
| Segmented (serrated) | Short fins welded in segments | 1,200°F | Good heat transfer, moderate fouling tolerance | Not for highest temperatures | General convection | Medium |
| Solid (helical) | Continuous helical wrap | 1,000°F | Highest area per foot | Plugging in fouling service | Clean flue gas service | Low-Medium |
| Embedded (L-foot) | Wound into groove in tube | 800°F | Low cost, good for clean service | Bond fails above 800°F | Low-temperature service | Lowest |
| Bare tube | No fins | Any | No fouling concerns, easy cleaning | Lowest heat transfer per foot | Shield section, dirty service | Lowest |
| Convection Section Fouling | ||||||
| Fouling of convection section extended surfaces reduces heat transfer and increases stack temperature. Causes of Fouling: • External (flue gas side): - Soot/carbon from incomplete combustion - Sulfuric acid condensation (below acid dew point, ~275-320°F) - Salt deposits from fuel contaminants - Erosion from particulate in flue gas • Internal (process side): - Coking/polymerization (feed preheat service) - Scaling (BFW economizer service) - Corrosion products Cleaning Methods: • Soot blowing: steam lances between tube rows (online, routine) • Water washing: offline, careful of thermal shock • Chemical cleaning: internal (process side) for coke or scale • Mechanical cleaning: scrapers, hydroblasting (turnaround) Monitoring: trend stack temperature — rising stack T at constant duty = convection fouling |
Source: Fired_Heater_Training_Curriculum_v1.xlsx · Sheet: Module 3 - Convection Section
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