Numerical investigation of hydrogen Co-firing in a 660 MW power plants: Combustion stability, heat transfer, and NOx formation

Abstract

Co-combustion of coal and low-carbon fuels in boilers can reduce CO2 emissions. Hydrogen, as a typical zero-carbon fuel, co-combusting with sludge and coal in a 660 MW tangentially fired boiler was studied by computational fluid dynamics, and combustion stability, heat transfer, and NOx formation were discussed in this research. The mixing ratio of hydrogen is 20%–60%, and in order to avoid the high rate of gas flow in local regions affecting the furnace combustion stability, hydrogen is injected into the boiler from one layer or two layers of secondary air nozzles. The impact of hydrogen on combustion affects the entire furnace, but mainly influences the upper nozzles region and the upper furnace. Flue gas temperature in the main burning region gradually decreases from 1728.8 K to 1494.6 K, as mixing ratios of hydrogen increase from 0% to 60%. The optimal case is in which the mixing ratio of hydrogen is 40% and hydrogen is injected into the boiler from two layers of secondary air nozzles, under these conditions, compared to solid fuel mono-combustion, the boiler heat flow is 1.04 times higher, and the NOx mass slightly increases at the furnace exit, about 1.13 times.