English 
There are significant differences between low-temperature economizers and ordinary economizers in terms of installation location, functional focus, material selection, and economy. The specific analysis is as follows:
Installation Location: Low-temperature economizers are located at the end of the boiler's tail flue
Low-temperature economizers are usually installed after the air preheater and before the dust collector (or before the desulfurization tower), in the low-temperature section of the boiler's tail flue (flue gas temperature: 120-250°C). This position allows them to recover low-temperature waste heat that ordinary economizers cannot utilize, while avoiding damage to subsequent environmental protection equipment (such as dust collectors and desulfurization towers) caused by high-temperature flue gas.
Ordinary economizers, on the other hand, are mostly installed in the middle section of the boiler's tail flue (e.g., high-temperature economizers) and directly come into contact with higher-temperature flue gas (usually 300-400°C). Their core task is to preheat the boiler feedwater to a temperature close to the saturation temperature.
Functional Focus: Low-temperature economizers balance energy conservation and environmental protection
The core function of low-temperature economizers is to recover low-temperature waste heat. By reducing the exhaust gas temperature (from 150-200°C to 100-130°C), they reduce exhaust heat loss (by 30%-50%) and improve the boiler thermal efficiency by 0.5%-0.8% per 10°C. In addition, they can optimize the environmental protection system:
Improve dust removal efficiency: After the flue gas temperature decreases, the sedimentation speed of dust particles accelerates, and the efficiency of electrostatic precipitators can be increased by 2%-5%;
Protect desulfurization equipment: Prevent high-temperature flue gas from accelerating the aging of the anti-corrosion lining of desulfurization towers, extending the equipment service life by 1-2 years;
Reduce white smoke plumes: Eliminate visual pollution caused by water vapor condensation by heating the clean flue gas after desulfurization.
Ordinary economizers mainly focus on preheating boiler feedwater, reducing the steam extraction volume of steam turbines, and improving the cycle thermal efficiency of generator sets by 0.3%-0.5%, but their synergistic environmental protection effect is weak.
Material Selection: Low-temperature economizers have lower costs
Since low-temperature economizers operate at a lower temperature (above the flue gas dew point), they can use ordinary carbon steel or ND steel (sulfuric acid dew point corrosion-resistant steel). The material cost is 10%-20% lower than that of ordinary economizers (which use high-temperature-resistant alloy steel).
Ordinary economizers, due to long-term contact with high-temperature flue gas, need to use high-temperature-resistant and oxidation-resistant alloy steel (such as 15CrMoG), resulting in higher material costs.
Economy: Low-temperature economizers have a shorter payback period
Taking a 300MW power station boiler as an example, after installing a low-temperature economizer:
Annual coal savings: 15,000-20,000 tons (calculated at a coal price of 1,000 RMB/ton, the annual cost savings are 15-20 million RMB);
Payback period: 2-3 years (only 1-2 years for industrial boilers).
Although ordinary economizers can improve boiler efficiency, their payback period is usually longer because their modification involves adjusting the heating surface of the boiler body.
Installation Location: Low-temperature economizers are located at the end of the boiler's tail flue
Low-temperature economizers are usually installed after the air preheater and before the dust collector (or before the desulfurization tower), in the low-temperature section of the boiler's tail flue (flue gas temperature: 120-250°C). This position allows them to recover low-temperature waste heat that ordinary economizers cannot utilize, while avoiding damage to subsequent environmental protection equipment (such as dust collectors and desulfurization towers) caused by high-temperature flue gas.
Ordinary economizers, on the other hand, are mostly installed in the middle section of the boiler's tail flue (e.g., high-temperature economizers) and directly come into contact with higher-temperature flue gas (usually 300-400°C). Their core task is to preheat the boiler feedwater to a temperature close to the saturation temperature.
Functional Focus: Low-temperature economizers balance energy conservation and environmental protection
The core function of low-temperature economizers is to recover low-temperature waste heat. By reducing the exhaust gas temperature (from 150-200°C to 100-130°C), they reduce exhaust heat loss (by 30%-50%) and improve the boiler thermal efficiency by 0.5%-0.8% per 10°C. In addition, they can optimize the environmental protection system:
Improve dust removal efficiency: After the flue gas temperature decreases, the sedimentation speed of dust particles accelerates, and the efficiency of electrostatic precipitators can be increased by 2%-5%;
Protect desulfurization equipment: Prevent high-temperature flue gas from accelerating the aging of the anti-corrosion lining of desulfurization towers, extending the equipment service life by 1-2 years;
Reduce white smoke plumes: Eliminate visual pollution caused by water vapor condensation by heating the clean flue gas after desulfurization.
Ordinary economizers mainly focus on preheating boiler feedwater, reducing the steam extraction volume of steam turbines, and improving the cycle thermal efficiency of generator sets by 0.3%-0.5%, but their synergistic environmental protection effect is weak.
Material Selection: Low-temperature economizers have lower costs
Since low-temperature economizers operate at a lower temperature (above the flue gas dew point), they can use ordinary carbon steel or ND steel (sulfuric acid dew point corrosion-resistant steel). The material cost is 10%-20% lower than that of ordinary economizers (which use high-temperature-resistant alloy steel).
Ordinary economizers, due to long-term contact with high-temperature flue gas, need to use high-temperature-resistant and oxidation-resistant alloy steel (such as 15CrMoG), resulting in higher material costs.
Economy: Low-temperature economizers have a shorter payback period
Taking a 300MW power station boiler as an example, after installing a low-temperature economizer:
Annual coal savings: 15,000-20,000 tons (calculated at a coal price of 1,000 RMB/ton, the annual cost savings are 15-20 million RMB);
Payback period: 2-3 years (only 1-2 years for industrial boilers).
Although ordinary economizers can improve boiler efficiency, their payback period is usually longer because their modification involves adjusting the heating surface of the boiler body.
