The flue gas recirculation device in the conventional circulating fluidized bed(CFB) oxy-fuel combustion system has been taken out and replaced with pure oxygen combustion

which is expected to reduce the overall energy consumption and CO_2 capture cost of the unit. Pure oxygen combustion will bring about problems such as uneven distribution of heat load and fluidization difficulty under minimal smoke gas flow

so a new boiler design should be carried out according to the flow pattern and heating surface layout in the furnace. This paper adopts the arrangement of immersed tube heating surface in the dense phase area to solve the local over-temperature problem.At the same time

a unique furnace structure design of “wide at the bottom and narrow at the top”

reducing the size of the bed material

increasing the primary air ratio and other methods are used to deal with the difficulties of material fluidization. Based on the CFB flow and heat transfer theory

a heat transfer calculation method of pure oxygen combustion CFB boiler is established

and a conceptual design of 130 t/h ultra-high pressure pure oxygen combustion CFB boiler is completed. The basic structure and overall layout scheme of boiler furnace

immersed evaporating heating tube

immersed superheater

cyclone

loop seal and economizer are given. Preliminary analysis shows that the new pure oxygen combustion CFB boiler can solve the problems of uneven distribution of heat load caused by high oxygen concentration combustion and the difficulty of material fluidization under minimal smoke gas flow. The designed boiler thermal efficiency can reach 94.83%

and the volume fraction of CO_2 and H_2O in the outlet flue gas is 57.1% and 38.4%

respectively. This paper lays a foundation for the future development of pure oxygen combustion CFB boiler technology and engineering practice for CCUS-EOR.