A 300 MW supercritical carbon dioxide(S-CO

2

) Brayton cycle oxyfuel power generation system is designed

and a simulation model is constructed using process simulation methods to study the effects of key operating parameters(such as the primary dry cycle flue gas ratio

the economizer side split ratio

the cold primary air temperature and the high-pressure turbine inlet pressure) on the system's thermal performance indexes. The effects of key operating parameters such as primary dry cycle flue gas ratio

economizer side split ratio

cold primar

y air temperature and high-pressure turbine inlet pressure on the system thermodynamics were investigated

and the thermal characteristics of the generating unit were revealed. The results show that

the boiler efficiency decreases with the increase of the proportion of primary dry-cycle flue gas

and when the proportion of primary dry-cycle flue gas reaches 50%

the net electric efficiency of the system is the highest

which is 42.93%. The boiler efficiency rises at first and then decreases with the increase of the coal economizer-side shunt ratio

and the net electric efficiency of the system reaches the highest(42.86%) when the coal economizer-side shunt ratio is 11%. With the increase of cold primary air temperature

the boiler efficiency keeps increasing

and the rising trend slows down and stabilizes at 99.29% at temperatures higher than 65 ℃

and the net electric efficiency of the system keeps increasing and reaches 43.06% at 95 ℃. With the increase of high-pressure turbine inlet pressure

the boiler efficiency firstly rises and then decreases

and reaches the maximum value of 99.35% at 29.5 MPa

and the net electric efficiency of the system reaches the optimal value(43.66%) at 29.0 MPa.