Flue gas waste heat recovery method of aluminum oxide gaseous state suspending calcining furnace

Abstract

The invention discloses a gas waste heat recovery method of aluminum oxide gas suspension calciner, which comprises the following steps: arranging a gas heat exchanger on a gas exhaust pipe between an electrostatic dust collector and an ID blower of the calciner to recover the waste heat of exhaust gas of the calciner; arranging a bypass flue at the inlet / outlet end of the gas heat exchanger; feeding condensed water from an aluminum oxide evaporation process to the gas waste heat recovery heat; and heating the water supply of the system in a two-stage heating form to improve the incoming water temperature of the gas heat exchanger. The heat recovered by the waste heat recovery can meet the requirement for heating aluminum hydroxide washing water of a pan filter. The method can freely adjust the quantity of gas passing through the gas heat exchanger according to the output of the calciner, and has the advantages of high heat exchange efficiency and adjustable resistance of the heat exchanger system. Meanwhile, the housing of the gas heat exchanger contacting the gas has high temperature to prevent acid dew point corrosion, thus improving the service life of the equipment. The temperature and the flow rate of hot water in the waste heat system can be adjusted freely.

Description

technical field [0001] The invention belongs to the field of heat energy utilization, and in particular relates to a method for recovering waste heat from low-temperature flue gas of a gaseous suspension roaster for alumina production. Background technique [0002] Gas Suspension Calciner (GSC) is a large-scale roasting device based on dilute phase and combined dilute and dense phase. Compared with other types of furnaces, it has the characteristics of large production capacity and low energy consumption. It has been well received in the alumina industry at home and abroad. It is widely used to dehydrate aluminum hydroxide to produce qualified alumina. The gas suspension roaster mainly uses coal gas or natural gas as fuel, and the flue gas contains corrosive gas SO 2 and SO 3 , The amount of smoke exhaust is large, reaching more than 100,000Nm3 / h per hour, the exhaust temperature reaches 170-200°C, and the smoke takes away a lot of heat. [0003] With the continuous and r...

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Problems solved by technology

[0004] The utilization of flue gas waste heat of alumina gaseous suspension roasting furnace belongs to low-temperature flue gas waste heat recovery, and the exhaust gas temperature cannot be lowered too low, otherwise the low-temperature flue gas will seriously corrode the metal wall surface and cause damage to the heat exchanger equipment; in addition, the entire gaseous suspension roasting Furnace airflow conveying and production capacity adjustment are carried out by an ID fan. The power margin of the ID fan is small, and the resistance of the flue gas heat exchanger is required to be within the power margin of the ID fan, which greatly limits the amount of waste heat recovery from the roaster flue gas.

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