Downstream boiler flue gas waste heat recovery system

Abstract

The invention discloses a concurrent recycling system for boiler smoke afterheat. The recycling system comprises a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is arranged on the high temperature side of a smoke flue and comprises a heat absorption section and a heat release section; the heat absorption section is connected with the heat release section through a first pipeline so as to form a circular loop; the heat absorption section is arranged in the smoke flue; the second heat exchanger is arranged on the low temperature side of the smoke flue; the second heat exchanger comprises an inlet collecting pipe and an outlet collecting pipe of a second pipeline; the first heat exchanger is connected with the second heat exchanger through a third pipeline; the heat release section of the first heat exchanger is arranged in the third pipeline; after heating medium is flowed into the third pipeline, the heating medium is flowed into the second heat exchanger through the inlet collecting pipe of the second heat exchanger and is flowed out of the outlet collecting pipe of the second heat exchanger. According to the invention, smoke temperature can be reduced lower; boiler smoke afterheat energy saving and recycling space is enlarged greatly; the temperature of boiler smoke which enters desulfurization and dedusting equipment is lowered; and operation cost of the desulfurization and dedusting equipment is saved.

Description

technical field [0001] The invention belongs to the field of energy and environmental protection, and in particular relates to a system for recovering waste heat from flue gas of a downstream boiler. Background technique [0002] At present, the fuel of most boilers in my country is still mainly coal, which contains S elements. After combustion, the flue gas discharged from the boiler contains acid gases. When the flue gas temperature is high, they will flow through the heating surfaces of the boiler in gaseous form. When the temperature of the flue gas is lower than a certain temperature, they will combine with the water vapor in the flue gas to form sulfuric acid and corrode the heat exchange equipment. Low temperature corrosion typically occurs in the cold end of the boiler air preheater and in economizers where the feedwater temperature is low. When the temperature of the heating surface is lower than the dew point of the flue gas, the sulfuric acid formed by the combin...

AI Technical Summary

Problems solved by technology

[0014] The above technologies and the listed patents make the wall temperature of the flue gas heat exchanger higher than the acid dew point temperature of the flue gas to avoid the problem of acid dew corrosion. space, there is the problem of incomplete cooling, based on this situation, the solutions listed in the present invention are given

Images