Numerical study and design strategy for a low emission coke oven system using oxy-fuel combustion of coke oven gas

Abstract

Abstract A low-emission coking process, which combines the oxy-fuel combustion with staged combustion strategy, was adopted to limit nitrogen oxides (NOx) emission and realize carbon dioxide (CO2) enrichment. The combustion process of coke oven gas (COG) in O2/CO2 atmospheres is numerically investigated in the combustion chamber of the coke oven. The velocity distribution, temperature fields, concentration of combustion products are predicted by the computational fluid dynamics (CFD) study. The results show that the peak gas temperature in the flue gas using O2/CO2 mixtures as oxidant is lower than that using air, leading to a dramatic reduction of NOx emission. The staged combustion strategy is proposed for the further reduction of NOx emissions. The key parameters such as the primary oxidant distribution ratio, oxygen excess ratio and oxygen concentration are optimized to be 0.8, 1.2 and 0.2, respectively. NOx emissions can be reduced to 65 ppm using staged combustion strategy, and CO2 concentration is improved to 95 vol% (dry basis) in flue gas. Using this low-emission coking process, CO2 in the flue gas can be easily captured for producing chemical products, and low-NOx emission in the coking oven system can be achieved.