Detection of gas-solid flow faults of a circulating fluidized bed using pressure fluctuations in wind caps

Wind cap partial blockages and agglomeration are two of the most common gas-solid flow faults that occur under the actual operations of circulating fluidized bed boilers. Using the method of measuring pressure fluctuations, for the characterization of fluid dynamics in fluidized beds, has a great advantage, due to its flexible adaptation to any operating conditions to monitor fluidization. This paper presents research into the use of measuring and analyzing pressure fluctuations in wind caps, for the analysis of the gas-solid fluidization characteristics in a fluidized bed with wind cap partial blockages or agglomeration fault. Partial blockages in a wind cap near feeding side and partial blockages in another wind cap near recycling side as well as agglomeration of different extents were simulated in a cold circulating fluidized bed. Pressure fluctuations in the inlets of several wind caps were measured at different primary air velocities under different fault conditions. They were then analyzed with the methods of statistical average, standard deviation, wavelet analysis and homogeneous index. Based on the calculated characteristic parameters, the effects of gas-solid flow faults on the gas-solid fluidization characteristics were analyzed. Results showed that variations of characteristic parameters of pressure fluctuations were related to variations of the gas-solid flow condition, which were caused by wind cap partial blockages or agglomerations. It is shown that the proposed method is practical.