The supercritical carbon dioxide(S-CO_2) Brayton cycle has attracted wide attentions owing to its high efficiency and compactness. However

for large scale(around 1 000 MW) S-CO_2 coal-fired power plants

the high S-CO_2 inlet temperature coupled with high combustion heat flux will induce the cooling wall overheating. In the present work

the coupled model between the furnace combustion and the S-CO_2 heat transfer is developed for the cooling wall thermal safety analysis. In one-dimensional calculation of the circumferential average cooling wall temperature

the flue gas recirculation method is introduced to reduce the cooling wall temperature

and the onedimensional cooling wall counter flow arrangement is further proposed. Moreover

the three-dimensional cooling wall temperature distribution is examined

and the spiral cooling wall is further introduced to reduce the circumferential hot spot temperature. The results show that

the optimization methods in the present work can effectively reduce the cooling wall temperature and eliminate the local hot spot

which can provide guidance for the engineering design of large scale S-CO_2 boilers.