The invention relates to a method and
system for comprehensive utilization of
tail heat of a boiler. According to the method and
system for comprehensive utilization of the
tail heat of the boiler, low-level steam extraction is carried out by means of a
turbine, in-boiler
cold air in a boiler air inlet duct connected with the boiler is heated by extracted steam through a steam
air heater, heated
cold air in the steam
air heater enters an air pre-heater through the boiler air inlet duct, heat exchange is carried out in the air pre-heater between part of
smoke from a boiler
economizer or a denitration device and the heated
cold air, and the other part of
smoke is used for heat exchange of part of supplied water through a
water supply economizer. According to the method and
system for comprehensive utilization of the
tail heat of the boiler, the low-pressure steam is extracted to heat the cold air so that the heat of the steam is recovered to reduce cold source loss, part of the high-temperature
smoke is saved at the same time, and the saved high-temperature smoke is used for heating part of the supplied water through an outlet
flue of the
economizer or an outlet
flue the denitration device; high-level extraction steam of the
turbine is saved due to the fact that the high-level smoke is used for heating part of the supplied water, the saved high-level extraction steam can continue to work in the
turbine, and then the efficiency of the turbine is improved and fuel
coal is saved.