Study on the effect of ammonia mixing ratio on process of ammonia and coal co-combustion

Abstract

Ammonia-coal co-combustion has emerged as a promising strategy for reducing carbon dioxide emissions. However, the quantitative impact of ammonia mixing ratios on the ignition and volatile combustion stages remains unclear, particularly under varying temperatures. In this study, a high-resolution optical measurement system coupled with Python-based image processing algorithms was developed to analyze the ignition distance, flame brightness, and morphology of pulverized coal particles.

Key findings include

At 1500 K, the ignition distance of pulverized coal increased from 9.0 mm to 16.5 mm as the ammonia mixing ratio rose from 0 % to 40 %, attributed to competing timescales between coal heating and ammonia product diffusion; At 1800 K and 1200 K, ammonia mixing exhibited negligible effects on ignition distance (6.5–6.7 mm and 5.5–4.7 mm, respectively), highlighting temperature-dependent dominance in combustion kinetics; Volatile ignition distance showed a negative correlation with ammonia mixing at extreme temperatures but a positive correlation at 1500 K, linked to oxygen competition and active species generation.

These results provide critical insights for optimizing ammonia-coal co-combustion systems in industrial applications.