In the context of carbon peak and carbon neutrality

the development of coal-biomass coupling power generation is one of the important ways to accelerate the transformation and upgrading of electric power and realize low-carbon development of coal power. A coal-fired power generation system directly coupled with biomass combustion was designed for a 300 MW circulating fluidized bed(CFB) boiler

and the combustion characteristics of directly firing biomass with coal were studied by using the system. The results show that

this biomass direct combustion coupling system could run stably and reliably. When wood pellets was co-fired in the CFB boiler

with the increase of wood pellets' blending ratio

the fly ash carbon content of the mixed fuel decreased

the CO emission reduced

and the burnout performance of the mixed fuel improved. After optimization on the boiler combustion and air distribution

the NOx emission was slightly lower than that of pure coal burning. The pollutants test under typical conditions showed that

after adding wood pellets

the dioxin emission from boiler flue gas was 0.008 8 ng TEQ/m~3(standard condition

φ(O_2)=11%)

and the dioxin emission in fly ash was 0.020 6 ng TEQ/m~3. The total emission of heavy metals and harmful trace elements such P

As and Se from fly ash was 32.121 mg/l

and that from the bottom slag was 3.918 mg/L. The emission of harmful substances like dioxins and heavy metals in flue gas and fly ash all met the emission limits of national environmental protection standards.