[Objective] To align with the national policy on low-carbon retrofitting of coal-fired power plants and tackle the dual challenges of cow dung pollution and underutilization of this resource in the animal husbandry sector of northern China, this study carried out a test on briquetted cow dung co-combustion in coal-fired power units, to explore a low-cost, easy-to-implement technical solution for both coal power decarbonization and livestock manure resource utilization. 

[Methods] This study selected a 350 MW coal-fired power plant in Inner Mongolia as the research subject and conducted briquetted cow dung co-combustion experiments adopting the "single-mill co-firing" 2 technology, with no retrofitting required for the existing equipment. Under co-firing ratios of 0%~20%, this study systematically investigated the effects of co-combustion on the adaptability of the pulverizing system, combustion characteristics of the boiler, pollutant emission characteristics, and performance of the dust removal system. 

[Results] The results show that when the co -firing ratio exceeds the range of 10% –15%, the mill current, specific power consumption, and pressure difference across the mill exhibit significant variations, with maximum increments of 3.96 A, 0.64 kWh/t, and 0.59 kPa, respectively. Furthermore, the fineness of pulverized coal decreases, with the two screen residue indices (R200 and R90) registering maximum increments of 1.95% and 6.53%, respectively. After co-firing briquetted cow dung, the boiler maintains stable combustion performance, with only slight fluctuations observed in furnace and flue gas temperatures. The CO concentration remains stable at 60.00 mg/Nm3, the carbon content of ash shows negligible variations, and boiler thermal efficiency undergoes a marginal decline with a maximum reduction rate of 0.20%. This co-firing technology exerts no significant influence on pollutant emissions and the operating parameters of the dust removal system. Under the pure coal combustion condition, the NO x concentration at the SCR inlet is 264.86 mg/Nm 3, and the SO 2 concentration at the desulfurization inlet is 2771.36 mg/Nm3. After co-firing, NOx generation shows a slight increase with a growth rate ranging from 3.94% to 8.19% (equivalent to an absolute increment of 10.45 –20.69 mg/Nm 3); SO 2 emissions experience a minimal reduction and remain essentially stable. Meanwhile, the current and voltage parameters of the electrostatic precipitator stay relatively stable, and the pressure difference across the bag filter section presents no obvious variation, with a maximum increment of only 72.87 Pa. 

[Conclusion] The findings demonstrate that utilizing the existing equipment of the unit enables the efficient co-combustion of cow manure, offering a replicable and scalable new technical paradigm for the resource utilization of livestock and poultry manure waste.