The invention provides a compound
combustion device and method for fuel decoupling staged micro-
fluidization grate-firing. The compound
combustion device comprises a grate-firing furnace and a
pyrolysis reactor. The fuel decoupling classification refers to that fine
coal particles are converted into
pyrolysis gas and high-temperature semi-
coke through a
cyclone pyrolysis reactor, the pyrolysis gas is introduced from the upper part of a main
hearth to be used for reducing
nitrogen oxide generated by
combustion of a
coal bed in a
bed layer area, and the high-temperature semi-
coke is conveyed to the upper surface of a
bed layer through a pipeline to assist in igniting the
coal bed; micro-
fluidized bed combustion refers to that
particle size distribution coal distribution is combined with primary air middle-front part air distribution, fine-particle coal in a bed layer is in a micro-fluidized combustion state in gaps of large-particle coal, combustion and
burnout of a bed layer coal sample are enhanced, and the carbon content of bottom
slag is reduced; the three-
hearth structural design is adopted,
fly ash return is coupled, fluidized
fly ash and gas-phase components are intensified to be burnt out, and then the carbon content of the
fly ash is reduced; through the layer combustion-chamber combustion combined combustion method, the incomplete combustion heat loss of the layer combustion furnace can be effectively reduced, the
boiler efficiency is improved, and the original emission of
nitrogen oxide is reduced.