Modeling and simulation of the start-up process of a 660MW ultra-supercritical circulating fluidized bed boiler

•Dynamic simulation model of 660MW ultra-supercritical circulating fluidized bed boiler.•“Core-annulus” flow structure for gas-solid phase.•Dynamic characteristics of hot and cold start-up processes. This study involved the development of a full-scale dynamic simulation model for a 660MW ultra-supercritical circulating fluidized bed (CFB) boiler–with the largest scale and maximum capacity. The boiler is presently under construction in China and includes a water-steam system, an air-flue gas system, a material supply system, and an ash circulation system. The gas–solid flow in the furnace was modeled based on the “core-annulus” flow structure, and the six-equation solution for the water–steam flow was used to simulate the dynamic behaviors of the water-steam system. Based on a design condition of 50% turbine heat acceptance (THA), a steady-state simulation model was established and calibrated. Consequently, cold and hot start-up processes at 0-50% THA were simulated to investigate the dynamic behaviors of the CFB boiler. Compared with the design conditions, the steady-state and transient simulation models demonstrated high accuracy.