Internal circulation composite phase change heat exchanger

Abstract

The invention discloses a composite phase change heat exchanger with inner circulation, which comprises a phase change heat exchanger that is divided into an upper section and a lower section as well as a composite gas water section that is additionally arranged under an original coal economizer in a flue gas channel and serially perforated with the original coal economizer; the upper section of the phase change heat exchanger is positioned in a wind channel of an original air preheater, and the lower section of the phase change heat exchanger is positioned in a back flue channel of the air preheater; an automatic control device of the phase change heat exchanger adjusts and controls heat exchange volume of the composite gas water section that is additionally arranged and wall temperature of the lower section of the phase change heat exchanger. The composite phase change heat exchanger with inner circulation has the advantages that flue gas afterheat is used not only for properly increasing the temperature of hot wind that enters a boiler, but also for directly heating water that is fed into the boiler, thus achieving the goal of simultaneously improving the boiler thermal efficiency and the output force, and a shunt path that is controlled by an automatic valve leads the lowest wall surface temperature of the heat exchanger always to be controllable and adjustable. The composite phase change heat exchanger with inner circulation can drastically lower the temperature of discharged flue gas, and simultaneously control the wall temperature of the heat exchanger always to be higher than the acid dew point of the flue gas, and avoid moisture condensation and corrosion.

Description

[Technical field] [0001] The invention relates to a device for recycling the waste heat of boiler flue gas, and specifically relates to a composite phase inversion heat technology that changes the original economizer and air preheater in the flue as a whole, and recycles the recovered flue gas. The waste heat is directly digested in the composite phase-change heat exchanger inside the boiler. [Background technique] [0002] There are usually economizers and air preheaters in the exhaust flue of power plant boilers. Due to SO in boiler flue gas 3 Existing, the flue gas outlet temperature of the heating surface at the tail of the air preheater is limited, and the exhaust gas temperature is too low, which will cause the wall surface temperature of the heating surface to be lower than the acid dew point of the flue gas, resulting in serious condensation corrosion and ash blocking, so the boiler The exhaust gas temperature is usually 140°C to 160°C or higher. The composite pha...

AI Technical Summary

Problems solved by technology

However, if the composite phase change heat exchanger is directly used in the economizer, and the recovered heat is used to heat the desalted water, the heat balance will be destroyed, and the heated desalted water may not be available.

However, if the composite phase change heat exchanger is directly used to heat desalted water to save the consumption of low-pressure steam, it may reduce the efficiency of the steam turbine after reducing steam extraction.

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