Waste heat recovery system and boiler system

The utility model relates to a waste heat recovery system and a boiler system, and aims to solve the technical problem that smoke discharge of an air duct is blocked due to the fact that a heat exchanger is easy to corrode and rust and is blocked by ash during traditional waste heat recovery on the premise that cost is not increased too much. Comprising a tubular shell connected to a flue in series, and a first heat exchanger and a second heat exchanger which are arranged in the shell; the temperature of the first heat exchange medium is higher than the dew point temperature of water vapor in the flue gas condensed on the outer surface of the first heat exchanger; the first heat exchanger is a finned tube heat exchanger made of common carbon steel; the second heat exchanger is located on the downstream of the first heat exchanger in the flue gas flowing direction, a second internal pipeline is arranged in the second heat exchanger and provided with a cooling water inlet and a cooling water outlet, the cooling