Numerical study on header effect of superheater's distribution headers when a circulating fluidized bed boiler operating at wide loads

To increase the proportion of new energy consumption while maintaining grid stability, thermal power units need to operate flexibly at a wider range of loads. The header effect has a significant impact on the flow distribution of the platen superheater of a circulating fluidized bed (CFB) boiler owing to the limited flow pressure drop in the platen. Therefore, accurate prediction of the static pressure distribution in the header is crucial for forecasting superheater tube wall temperatures, thereby ensuring safe boiler operation. This paper first investigates the flow behavior, static pressure distribution, and flow distribution of two distribution headers of a CFB boiler under wide load conditions. Subsequently, based on the simulation results, the predictive accuracies of the header static pressure calculation models in existing relevant Standards are evaluated, found that the formula in existing Standards cannot accurately account for the wide-range variations in header diameters and boiler loads. Finally, based on numerical simulations of headers with six different diameters (ranging from 150 mm to 400 mm) under wide load conditions, a new predictive correlation for static pressure distribution within distribution headers is proposed, which effectively represents the complex influence of header diameter and boiler load on static pressure within distribution headers.