Working Principle of Cast Iron Finned Economizer

Counter-flow Heat Exchange Logic
It adopts a counter-flow heat exchange structure and is installed in the flue at the boiler tail. High-temperature flue gas flows downward to scour the outer fins, while low-temperature boiler feedwater flows upward inside cast iron tubes. Opposite flow direction maintains the maximum temperature difference for stable heat transfer.
Internal Water Circulation Process
Cold softened feedwater enters the bottom flange header, then flows upward layer by layer through integrally cast curved elbows of each finned tube. Heat transfers continuously from cast iron wall to internal water, and heated feedwater finally exits from the top flange to the boiler steam drum.
External Flue Gas Heat Absorption Process
High-temperature ash-laden flue gas washes the cast iron fins, whose enlarged radiating area recovers waste heat fully. The silicon-rich cast iron forms a silica protective film at high temperature to resist fly ash abrasion and low-temperature acid dew corrosion. Wide gaps between fins avoid ash blockage and stable flue flow. Cooled flue gas is then sent to dust removal and desulfurization equipment.
Thermal Cycle Function Principle
Energy saving: Recover waste flue heat to preheat feedwater, cutting fuel consumption and raising boiler thermal efficiency.
Reduce thermal stress: Narrow temperature gap between feedwater and furnace surfaces, protecting steam drums and water walls from thermal shock damage.
Optimize combustion: Stable furnace temperature improves burnout of wet biomass fuels and reduces incomplete combustion loss.
Simplified Working Flow
Low-temperature feedwater enters the bottom → Absorb heat inside cast iron tubes upward
High-temperature flue gas enters from furnace top → Release heat outside cast iron fins downward
Heated feedwater feeds boiler → Cool flue gas exhausts after purification