Numerical analysis of carrier gas characteristic effects on flow dynamics and combustion efficiency in natural gas and pulverized coal injection

• Reducing carrier gas injection rate from 4000 to 2000 m3/h increases tuyere temperature and CO/H2 mole fractions but decreases pulverized coal burnout. • Increasing carrier gas temperature by 20 K raises raceway temperature by 20.6 K, enhancing volatile release and combustion, yet only 1.16% burnout improvement from 373 to 393 K. • Optimal carrier gas temperature is around 373 K to balance coal transport and combustion performance. • Using air as carrier gas boosts pulverized coal burnout by 2.69% compared to N2, offering a practical strategy for efficiency improvement.