Experimental and numerical study of ammonia addition effects on combustion characteristics of Coke Oven Gas (COG) in a premixed flame

This study investigated the fundamental combustion characteristics of Coke Oven Gas (COG) emitted in steel making process and established database to support its use as a recycled fuel. From economic perspective, hydrogen, which constitutes more than half of COG, can be extracted for other applications from the COG. To address this issue, hydrogen-removed COG (RCOG) was analyzed for its potential use as recycled fuel in industrial applications. Combustion characteristics, including the laminar burning velocity (LBV), flame stability, radical visualization, and NO x emission, were examined to construct a foundational database for the target fuels. LBV and species mole fraction were predicted using ANSYS Chemkin-Pro with various reaction mechanisms. Results showed that the maximum LBV of COG was approximately 78 cm/s, nearly double that of RCOG. Among the tested mechanisms, GRI3.0 provided the most accurate predictions for fuels which has complex compositions such as COG and RCOG. The addition of ammonia to the fuel reduced LBV and narrowed the flame stability limits due to its low combustion reactivity. Flame visualization revealed that increasing the ammonia content reduced the amount of fuel pyrolysis products, resulting in lower formation of carbon-containing excited radicals. NO x emissions increased with increasing ammonia content in the fuel.