Hydrodynamic characteristics in the full-loop circulating fluidized bed under load regulation. Part 1: Experimental investigation

The hydrodynamic characteristics of the gas–solid flow in the circulation loop play a fundamental role in the dynamic behavior of circulating fluidized bed (CFB) boilers under load regulation. In the available prediction models, the gas–solid flow behavior in the circulation loop is characterized by steady-stated based correlations, which casts doubt on the reliability of these models. To explore the rationality of applying the steady-stated based correlations in the description of the flow behavior under load regulation, experiments at different ‘load’ change rates were performed in a CFB test rig. By comparing the experimental data obtained under ‘load regulation’ conditions with those measured under the corresponding steady-state conditions, the accuracy of the steady-stated based correlations was evaluated. The results revealed that the direct use of these correlations may bring considerable error. In addition, despite the difference in the ‘load’ change rate, the CFB system would eventually reach the same steady state.