The exhaust temperature of boiler in current supercritical carbon dioxide coal-fired power systems is about 120 ℃. The efficiencies of the coal-fired power system and flue gas dust collector can be enhanced by further cooling the boiler exhaust temperature with system optimization. Therefore

by taking a 1 000 MW coal-fired power plant as the example

improved configurations with low-temperature flue gas heat recovery system were proposed by coupling and matching of the air pre-heating process

heat regenerative process and flue gas cooling process. Moreover

the thermodynamic and technical economic models were developed

and the configurations were economically optimized. The results show that

the exhaust temperature can be decreased to about 95 ℃ when the low temperature economizer is integrated together with the main compressor intercooling and flue bypass ahead the air-preheater. Compared with the basic configuration

the improved configuration 4's boiler efficiency increases by 1.5% and the power plant efficiency increases by 1.45%. By analyzing the influences of fuel cost and running time on the electricity cost

it is proved that the improved configuration 4 has the lowest levelized cost of electricity and the best economic effect.