Preheating of air and flue gas waste heat utilization system that energy cascade utilized

The utility model belongs to the fields such as heat recovery of boiler flue gas and production technology tail gas specifically, relate to a preheating of air and flue gas waste heat utilization system that energy cascade utilized. The utility model discloses a: flue gas passageway (17), air duct (20), air heater (9), low -temperature level condensate water flue heat exchanger (8), high temperature level condensate water flue heat exchanger (2), condensate water air duct heat exchanger (19) and low pressure feed water heater (4) wherein, still include: the condensate water comes water header (15), condensate water return main (12) and condensate water house steward (22). The utility model discloses combine total heat recovery system of flue gas waste heat utilization, preheating of air and unit steam turbine and boiler, with preheating of air and heat utilization hierarchy configuration, the improvement of two aspects of implementation system safety and efficiency simultaneously. The preferential condensate