Method and device for flue gas waste heat utilization of aluminum oxide roasting furnace

Abstract

The invention relates to a method and device for flue gas waste heat utilization. Flue gas of an outlet of an electric dust collecting device enters the lower portion of a waste heat recovery device from the lower portion of a flue gas waste heat recovery device through a flue gas pipeline, after performing indirect heat exchanging with hot water in the lower portion of the waste heat recovery device, the flue gas enters the upper portion of the waste heat recovery device from a fuel gas connecting pipe to perform direct heat exchanging with cold water, and the cold water is pumped into the upper portion of the flue gas waste heat recovery device from the interior of a cold water pipe through a cold water pump; 70-80-DEG C hot water which is generated after the cold water is processed through direct heat exchanging automatically flows into the lower portion of the waste heat recovery device and then performs indirect heat exchanging with hot flue gas at the lower portion of the waste heat recovery device, and 85-95-DEG C hot water generated after heat exchanging automatically flows to a bottom hot water tank and delivered to a procedure needing the hot water through a hot water pump. The temperature of the recovered hot water can reach 85 DEG C to 95 DEG C, the hot water can be directly used for red mud washing and aluminum hydroxide washing, sensible heat and latent heat in the flue gas can be fully recovered, and more than 25 kg of standard coal can be saved every one ton of aluminum oxide.

Description

technical field [0001] The invention relates to a method and a device for utilizing flue gas waste heat, in particular to a method and a device for utilizing flue gas waste heat of an alumina roasting furnace in alumina production. Background technique [0002] In the production of alumina plants, gaseous suspension roasters, fluidized flash roasters or circulation roasters are used to roast aluminum hydroxide to remove crystal water and attached water in aluminum hydroxide, and complete part of the crystal transformation to obtain the final product. alumina products. The temperature of the exhaust gas discharged from the roaster is about 135 ° C ~ 180 ° C, and the exhaust gas contains about 40% ~ 55% water vapor, so the exhaust gas will take away a large amount of sensible heat and latent heat. If this part of water and heat is not recovered Using it is undoubtedly a waste. At present, some domestic alumina factories take measures to recover the waste heat of the flue gas...

AI Technical Summary

Problems solved by technology

However, this flue gas waste heat recovery method only uses part of the sensible heat of the flue gas. For the flue gas of the kiln, the sensible heat of the flue gas only accounts for about 12% of the total heat of the flue gas, and about 88% of the heat is Latent heat of water vapor in flue gas

There is also a way to recover the latent heat in the flue gas by direct heat exchange, but due to the dew point of the flue gas water, the water temperature after recovery is only 70-80°C, and the hot water at this temperature needs to be heated to 85-95°C to meet the requirements of aluminum oxide. The needs of red mud washing and aluminum hydroxide washing in the factory

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