Numerical simulation of hydrogen co-firing distribution on combustion characteristics and NOx release in a 660 MW power plant boiler

Abstract

The article discussed the influence on furnace temperature distributions, combustion characteristics, and NOx release when hydrogen, coal, and sludge co-firing in a 660 MW power plant boiler by CFD. Non-premixed combustion model was chosen as the gas combustion model. As the height of the hydrogen injection position rises, the temperature difference in the main combustion region decreases from 297.22 K to 94.72 K. The co-combustion of hydrogen inhibits solid fuels' combustion. As hydrogen nozzles' height decreases, the NOx mass at the furnace outlet increases from 98.41 % to 160.38 %. When the excess air coefficient changes from 1.15 to 1.35, the temperature in the main combustion region significantly increases, while the temperature in the upper furnace decreases, and the heat flux of the main combustion region increases by 11.10 %, the heat flux of the total furnace decreases by 1.39 %, the NOx mass at the furnace outlet increases by 31.67 %. The optimum co-combustion method is injecting the hydrogen from the top hydrogen nozzles and the excess air coefficient is 1.15, the overall impact on the furnace is minimal in this way. The fundamental reason hydrogen affects co-combustion is the fuel characteristics’ difference between hydrogen and solid fuels.