Analysis of the processes in fluidized bed boiler furnaces during load changes

Due to increased share of intermittent renewable energy production, flexibility demands for boiler based energy production have increased in the form of required faster ramp rates and lower allowed minimum loads. To illustrate the effects of changes in boiler load, the present paper focuses on analysis of furnace processes in bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) combustion during a load change. Computational fluid dynamic (CFD) modeling is used as the analysis tool. The paper illustrates by means of simulations what changes take place in the temperature and composition distributions. The effects on emissions are also analyzed in the case of the BFB boiler. The differences between CFB and BFB furnaces in their capability to respond to load change demands are discussed