The invention discloses a
coal-fired power
plant flue gas heat
regenerative system and an energy-saving water-saving ultra-clean discharging method. The temperature of the
flue gas is reduced to about 90-110 DEG.C through a low-temperature
coal economizer, and the recycled
flue gas heat heats primary and secondary wind entering a boiler through a steam air heaters, so that the first stage of heat regenerative cycles is achieved. The temperature of the
flue gas at the outlet of a desulfurization
tower is reduced to 30-40 DEG.C through a vacuum
flash evaporation and solidification device and a low-temperature
heat pump heat exchange device, and a part of
water vapor of the
flue gas is condensed and collected, so that water is saved. The low-temperature
heat pump heat exchange device absorbs the
latent heat released in
flue gas sensible heat and condensation processes, and dry as-fired
coal and air are heated, so that the second stage of heat regenerative cycles is achieved. A
boiler slag discharge system recycles the
waste heat of heat
slag, and the as-fired coal is heated, so that the third stage of heat regenerative cycles is achieved. When the
waste heat is not used up, the remained
waste heat can be utilized, so that energy is saved. Low-temperature desulphurization
slurry led out from the vacuum
flash evaporation and solidification device is injected into the desulfurization
tower, so that the desulphurization efficiency is improved, and an ultra-clean discharging objective is achieved.