SS Tubes Condenser for 2x125 MW Coal Fired Thermal Power Plant

SS Tubes Condenser for 2x125 MW Coal Fired Thermal Power Plant

Dry coolers are heat transfer equipment that use air as the cooling medium, and are mainly used in coal-fired thermal power plants for heat dissipation needs in areas where water is scarce or water quality is harsh, complementing traditional wet cooling towers. Its core roles include:

Turbine exhaust cooling: replacing part of the wet condensing system, realizing “dry cooling power generation” (e.g. air-cooled island);

Auxiliary system heat dissipation: cooling of lubricating oil, generator hydrogen, boiler feedwater preheating and other auxiliary processes;

Water conservation and consumption reduction: saving over 90% of water compared with the wet system, adapting to the water-scarce mining areas of the power plant.

Core applicability of stainless steel

corrosion-resistant environment: coal-fired power plant air containing SO₂, dust, fly ash, stainless steel (such as 316L, 2205 duplex steel) can withstand acidic gas condensate (pH ≤ 4) and fly ash abrasion;

high-temperature performance: stainless steel melting point ≥ 1350 ° C, can withstand the long term scouring of the steam or high temperature fluids in the pipe (eg, 300 ~ 500 ° C) to avoid high temperature oxidization of ordinary carbon steel; anti-ash accumulation characteristics: compared with wet system water savings of more than 90%. High temperature resistance: stainless steel melting point ≥1350℃, which can withstand the long-term scouring of steam or high temperature fluid (e.g. 300~500℃) inside the tube, avoiding the oxidization of ordinary carbon steel;

anti-dust accumulation characteristics: smooth surface reduces the adherence of dust, and with the design of fin inclination (e.g. 15°~30°), reducing the probability of dust accumulation.

Specific application scenarios in coal-fired power plants

Air-cooling island (dry cooling of turbine exhaust steam)

System composition: A or zigzag array of hundreds of stainless steel tube dry coolers, with exhaust steam inside the tubes (pressure of 4~8 kPa, temperature of 50~80℃), and air flow rate outside the tubes of 2~3 m/s.

Efficiency indexes: heat transfer coefficient of about 30~50 W/(m²・K), which is about 50% lower than that of the wet condenser, but water consumption is negligible. Typical case: a 2×660 MW coal-fired power plant in Northwest China adopts 316L stainless steel air cooler, and the annual water saving reaches 5 million tons.

Cooling of auxiliary equipment

Hydrogen cooling for generator: hydrogen is passed inside the pipe (pressure 0.3~0.5 MPa, temperature 60~80℃), and the temperature of hydrogen is ≤45℃ after air cooling outside the pipe;

Lubricating oil cooling for boiler feed pump: lubricating oil is passed inside the stainless steel pipe (temperature 70~90℃), and the temperature of oil is ≤50℃ after air cooling to avoid the oil sludge deposition in carbon steel pipe.

Flue gas waste heat recovery

Stainless steel pipe dry cooler is installed in the tail flue to recover the flue gas waste heat (180~220℃) to heat the air and improve the efficiency of the boiler by 1%~2%;

2205 duplex steel is required to resist the dew point corrosion of SO₂+H₂O in the flue gas.