Recovery system of waste heat from flue gas

A recovery system of waste heat from flue gas, the system comprising:

• a) a first heat exchanger, the first heat exchanger comprising a heat absorption section, a heat release section, and a first pipeline;
• b) a second exchanger, the second heat exchanger comprising a second pipeline comprising an inlet header and an outlet header;
• and
• c) a third pipeline;
• wherein
• the first heat exchanger is disposed at a relatively high temperature side of a flue, the second heat exchanger is disposed at a relatively low temperature side of the flue, and the first heat exchanger and the second heat exchanger are connected by the third pipeline;
• the heat absorption section and the heat release section are connected by the first pipeline to form a circulation loop;
• the heat absorption section is disposed in the flue;
• the heat release section is disposed in the third pipeline;
• and
• when in use, a medium to be heated is introduced to the second exchanger along the third pipeline and the inlet header in sequence for heat exchange, and flows out from the outlet heater of the second exchanger.