A coal-fired power plant sought to improve thermal efficiency by recovering low-grade
heat from boiler exhaust gas downstream of the air preheater. Conventional metal economizers failed to
deliver reliable performance below the acid dew point while minimizing maintenance and pressure loss.
A fluoroplastic-steel low-temperature economizer system was selected to maximize heat recovery while
offering long-term corrosion resistance.
| Item | Value |
| Boiler Capacity | 300 MW Unit |
| Flue Gas Flow Rate | 920,000 Nm³/h |
| Flue Gas Inlet Temperature | 150°C |
| Flue Gas Outlet Temperature | 85°C |
| Heating Water Flow Rate | 1,500 t/h |
| Heating Water Inlet Temperature | 50°C |
| Heating Water Outlet Temperature | 80°C |
| Flue Gas-Side Resistance | ≤ 900 Pa |
* Representative project data for a utility boiler waste heat recovery application. *
Conventional metal economizers experience severe corrosion as flue gas temperatures approach the acid dew point.
Large quantities of recoverable thermal energy are discharged through the stack.
The plant required continuous operation with minimal maintenance interruption.
The recovery system had to maintain low flue-gas side resistance to avoid affecting boiler operation.
Installed between the induced draft fan and desulfurization tower, the economizer recovers waste heat to supply energy to district heating water and plant utility systems. Combining its system to:
Flue gas temperature reduced from 150°C to 85°C.
Recovered heat reused within the plant and district heating network.
Reliable performance under acidic condensation conditions.
Significant reduction in corrosion-related failures and shutdowns.
Recover additional usable thermal energy from boiler exhaust gas.
Lower fuel consumption through improved heat utilization.
Maintain stable performance under corrosive conditions.
Reduce maintenance and replacement costs over the system lifetime.
