The invention discloses a
flue gas extremely-deep
waste heat recovery system and method for desulfurization
slurry grading
flash evaporation, and belongs to the technical field of
coal-fired boiler
waste heat heat supply. Desulfurization
slurry grading
flash evaporation, injection pressurization and boiler
combustion-supporting
air heating and humidifying technologies are combined, deep
flue gas
waste heat recovery is achieved, the
water temperature of a
heat supply network is greatly increased, and the process comprises the following steps that desulfurization
slurry is firstly fed into a front
flash evaporation tank to be subjected to first-stage negative pressure flash
evaporation, and flash
evaporation steam is used for conducting first-stage preheating on return water of the
heat supply network; the first-stage concentrated slurry is sent to an injection flash tank for second-stage negative pressure flash
evaporation, flash steam is sent to a negative pressure
injector and is driven by heat supply steam to be pressurized into medium-pressure steam, and then second-stage large-temperature-difference heating is conducted on heat
supply network return water; sending the second-stage concentrated slurry to a final-stage flash tank for final-stage negative-pressure flash evaporation, heating intermediate water by flash evaporation steam, and returning the final-stage slurry to a desulfurized water
system; the intermediate water is fed into the total heat
air preheater, and is fed into the boiler after heating, humidifying and overheating the inlet air of the boiler, so that the steam content of
flue gas and the temperature of a desulfurization slurry outlet are increased.