Boiler tail exhaust gas heat utilization system

Abstract

The invention discloses a boiler tail exhaust gas heat utilization system which comprises multiple stages of preheaters with the progressively-increasing and mixed temperatures and a coal economizer. The preheaters are communicated with the coal economizer through a flue. The boiler tail exhaust gas heat utilization system further comprises a secondary flue (13) penetrating through all the preheaters. Some heat of boiler tail exhaust gas is absorbed by the coal economizer, and the rest of the heat is totally used for heating primary air and secondary air entering a boiler, so that the boiler efficiency is improved by 0.5%-2%, and the coal consumption is lowered.

Description

technical field [0001] The invention relates to the technical field of boilers, in particular to a boiler tail flue gas heat utilization system. Background technique [0002] At present, exhaust smoke loss is the largest item among all heat losses of utility boilers. In the exhaust heat loss, the exhaust temperature is an important factor, and the high exhaust temperature leads to a large exhaust heat loss. Therefore, reducing exhaust gas temperature is an effective measure to reduce exhaust heat loss and improve boiler efficiency, thereby reducing coal consumption and pollutant emissions for power generation. [0003] The current power plant boilers mainly use rotary air preheaters to reduce the exhaust gas temperature and heat the air. Due to the limitations of volume, weight, layout requirements and low-temperature corrosion, the exhaust gas temperature generally drops to 120~130 °C, and the lowest can be reduced to 115 °C. ℃. On this basis, further increasing ...

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Problems solved by technology

[0005] The low-temperature economizer does not belong to the category of boilers, and cannot reduce the exhaust gas temperature and improve the boiler efficiency. Although the low-temperature economizer further reduces the flue gas temperature, it belongs to waste heat utilization and saves low-quality low-pressure, low-temperature steam. Its working ability is limited. If the flue gas temperature is reduced from 115°C to 90°C, the temperature drop of 25°C can reduce the coal consumption by about 1.10g / kWh, which has little effect on improving the efficiency of the boiler.

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