The engineering task
Hot flue gas is used to generate steam or hot water. Achievable duty depends on fuel, excess air, flue-gas composition and permissible stack temperature.
A lower outlet temperature appears to improve efficiency but may cross the acid dew point and cause corrosion. Heating area, gas-side pressure drop, stack draught and fan power therefore form a coupled optimisation.
Required design data
- Fuel composition, firing rate and excess air
- Flue-gas inlet and allowable outlet temperature
- Steam/water pressure and feedwater state
- Allowable backpressure, fuel sulphur and materials
Technical solution approach
Balance combustion
Determine air demand, flue-gas flow and composition from fuel and excess air.
Set recoverable heat
Use enthalpy flow, radiation and stack losses to establish transferable duty.
Size heating surface
Temperature programme, heat transfer and fouling margins define bundle and coil.
Check the gas path
Balance bundle loss and natural stack draught across all loads.
Check corrosion and safety limits
Keep outlet and cold surfaces above acid dew point with margin; protect steam side and upset cases.
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.