Views: 5 Author: Site Editor Publish Time: 2025-07-02 Origin: Site
Design Considerations of Bare Tube Low Pressure Boiler Economizer
Pressure and Temperature Constraints
Lower Pressure: Operates with feedwater pressures typically <2.5 MPa (vs. high-pressure economizers at 10–15 MPa), matching the low-pressure feedwater circuit (e.g., preheating condensate or deaerator inlet water).
Flue Gas Temperature: Targets low-temperature flue gases (150–300°C) to avoid condensation of corrosive acids (e.g., sulfuric acid, which forms below the acid dew point ~120–150°C for high-sulfur fuels). Bare tubes, with simpler geometry, are easier to fabricate with corrosion-resistant materials if needed.
Tube Bundle Sizing
Heat Transfer Area: Calculated based on the desired heat recovery (e.g., 5–15% of total boiler heat input) and log mean temperature difference (LMTD) between flue gas and feedwater. For example, a 100 MW boiler may require a bare tube bundle with 500–1,000 m² of surface area.
Pressure Drop: Balanced to avoid excessive fan energy consumption. For flue gases, pressure drop is typically limited to 200–500 Pa; for feedwater, <50 kPa.
