Numerical study of process and emissions characteristics of natural gas reburning.

The numerical simulation with CFD software FLUENT6. 1 on natural gas reburning in coal-powder furnace was conducted to study the relationship between pollutants (NO_x, CO₂ and CO) emissions, unburned carbon in fly ash (UBC) and heat efficiency of coal-powder furnace. The results indicate that natural gas reburning can effectively reduce NO_x emission while keeping fuel fully burning and high heat efficiency. The optimum range of natural gas fraction, injection location of reburning fuel and stoichiometric ratio in rich zone are proposed. The computational results are in good agreement with the experimental ones, which indicates that the numerical calculation method has practical value of application in engineering. It is suggested that through a certain extent reconstruction to boilers, the gas reburning technology can reach a low level of NO_x emission [ABSTRACT FROM AUTHOR]