Investigation of non-uniform characteristics in a 300 MWth circulating fluidized bed with different coal feeding modes

Circulating fluidized bed (CFB) has been practised in many engineering fields, but the non-uniform char-acteristics deteriorate combustion performance and system control. In this study, the improvement of external-loop and in-furnace non-uniformity of a 300 MWth industrial-scale CFB with multiple cyclones by a dual-side coal feeding mode was numerically quantified. The results show that the pressure is non-uniformly distributed among three external loops, where the pressure in the middle loop seal is lower than that in the corner loop seals by 4.5 %. The pressure gradient positively correlates with the solid holdup. As compared with the traditional single-side coal feeding mode, the dual-side coal feeding mode: (i) promotes the final mixing degree by 11.15 %; (ii) extends the residence time of coal particles by 10.3 %; (iii) reduces the magnitude and fluctuation of the horizontal solid flux by 28.5 % and 77%, respectively; (iv) narrows the temperature range and reduces the mean temperature by 7 degrees C; (v) enhances the com-bustion of coal particles by consuming more O2; (vi) decreases the concentrations of SO2 and NO by 3 % and 5 %, respectively. The present study shows the superiority of the dual-side coal feeding mode to the traditional single-side coal feeding mode in the optimization of CFBs in practical industrial processes.(c) 2023 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Automated summary

The improvement of external-loop and in-furnace non-uniformity of a 300 MWth industrial-scale circulating fluidized bed (CFB) with multiple cyclones by a dual-side coal feeding mode was numerically quantified. The dual-side coal feeding mode showed superiority over the traditional single-side coal feeding mode in terms of final mixing degree, residence time of coal particles, solid flux characteristics, temperature range, combustion efficiency, and emissions reduction.