Effect of kaolinite on control of hard deposit formation and alteration of fine particles in a commercial circulating fluidized bed boiler burning solid refuse fuel

Solid refuse fuels (SRF) and biomass contain significant amounts of KCl and NaCl which result in operation problems such as hard deposit formation in combustion. The effect of kaolinite in the decomposition of mineral chlorides in a commercial SRF-burning CFBC boiler is investigated. The injection of kaolinite with SRF in a commercial CFBC shows its effect on mineral chloride decomposition thus softens the hardness of the deposit on the heat exchanger tubes in the convection pass. By the reaction of molten salt with kaolinite, particles under 5 mu m in the flue gas is significantly reduced. After 37 days operation with kaolinite use the PM 10 particle in flue gas is reduced originally 86 mg/Nm(3) to 16 mg/Nm(3), which is 81% reduction. The reaction of physical and chemical adsorption of metallic oxide component to kaolinite particle is also monitored by SEM images. This result is reflected to the particle side distribution of the fly ash in that the shift of the abundant particle size peak to a larger size cut after the use of the kaolinite. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The addition of kaolinite in a commercial SRF-burning CFBC boiler has been found to reduce the decomposition of mineral chlorides, soften the hardness of deposits on heat exchange tubes, and significantly decrease particulate matter in flue gas, leading to a shift in particle size distribution towards larger sizes.