Bypass economizer used for comprehensive utilization of flue gas waste heat

The utility model relates to a bypass economizer used for comprehensive utilization of flue gas waste heat. Flue gas loss is the most important heat loss in boiler operation, exhaust gas temperature of a number of boilers in thermal power plants in china exceeds a design value largely, but so far no economizer can save coals by the utilization of the flue gas waste heat. The bypass economizer used for the comprehensive utilization of the flue gas waste heat comprises a low-voltage economizer body (1) which is connected with a low-voltage economizer inlet collecting box (2), a low-voltage economizer inlet sub-control collecting box (3), a low-voltage economizer outlet sub-control small collecting box (4), a low-voltage economizer outlet collecting box (5), a low-voltage heater A (6) and a circulating water pump (7), and the circulating water pump is respectively connected with a low-voltage heater B (8), a low-voltage heater C (9) and a low-voltage heater D (10). The bypass economizer used for the comprehensive utilization of the flue gas waste heat is used in the boiler and used for coal saving of the boiler.