Both the low temperature economizer and gas-gas heater(GGH) have good energy saving effect and environmental protection effect

but they could not be arranged simultaneously in coal-fired power plants.To solve this problem

a clean and efficient coordinated system was put forward.In this system

by using coal pre-drying technology

a low-temperature economizer is arranged in tail of the boiler while a GGH is arranged after the dryer.Moreover

by taking a typical ultra supercritical 1 000 MW unit coal-fired unit with single reheat cycle as case unit and the conventional low temperature economizer and GGH systems as reference systems

thermodynamic and economic analysis of the new system were conducted.The results indicate that

the proposed system will increase the power production by 14.7 MW and recover water of 13.9 kg/s

which can bring annual economic benefit of 26.24 million yuan

indicating the energy saving effect and economic benefit is dramatic.The final exhaust temperature will be heated up to over 80 ℃

and the buoyancy lift and pollutant dilution capacity of the flue gas can be greatly enhance.Furthermore

the annual CO_2 emission reduction in the proposed system will be 54 314 t

which resulted in benefit to pollutant attenuation and environmental protection.