Recycling method of output coal gas in iron making technology

Abstract

The invention relates to a recycling method of output coal gas in an iron making technology. Generated coal gas of a final reduction reactor is subjected to dust removal by hot whirlwind; a part of generated coal gas enters a pre-reduction reactor as reduction coal gas for use; the other part of generated coal gas is subjected to dust removal, dehydration, cooling and secondary dust removal; another part of generated coal gas is used as surplus coal gas to be mixed with pre-coal gas generated by the pre-reduction reactor to form output coal gas; another part of generated coal gas is used as cold coal gas which is pressurized and then mixed with the generated coal gas through a cold coal gas line; a bypass branch line is also arranged in the cold coal gas line and is connected with the surplus coal gas line; redundant cold coal gas is discharged from the surplus coal gas line through the bypass branch line; after being pressurized, transformed and absorbed to release CO2, the output coal gas is delivered into the cold coal gas line and is mixed with the generated coal gas; and after being cooled, the generated coal gas as the reduction coal gas enters the pre-reduction reactor for use. In the invention, according to furnace conditions and the characteristic of instability of smelting rate, fuel ratio and factory energy consumption are reduced to the maximum; and the working modes of the coal gas line are flexibly switched.

Description

technical field [0001] The invention relates to a two-stage ironmaking process, in particular to a recycling method for output gas in the ironmaking process, which can realize flexible switchover of gas lines for certain specific processes when the fuel ratio is reduced and operating parameters are changed. Background technique [0002] The two-stage smelting reduction process includes two processes of gas-based pre-reduction and final reduction smelting. The gas-based pre-reduction process uses high-temperature gas to preheat and pre-reduce massive natural lump ore and pellets. The pre-reduction device is a traditional single reactor; the final reduction smelting is to perform final reduction and smelting of the pre-reduced product to finally become At the same time, the molten iron generates gas through combustion and other reactions for pre-reduction, and the final reduction reactor is also a single reaction device. [0003] With the improvement of process furnace condit...

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Problems solved by technology

[0003] With the improvement of process furnace conditions, the fuel ratio (coal + coke consumed for smelting one ton of iron) continues to decrease, and the gas production decreases. When the smelting rate (production efficiency) is 140t / h, the fuel ratio (excluding moisture) is lower than 900kg / tHM, the excess gas volume (gas production per hour of final reduction reactor - gas consumption per hour of pre-reduction) is less than 10000Nm 3 / h, and the fluctuation is large, resulting in an increase in the fluctuation frequency of the process system pressure (the pressure of the vault of the final reduction vessel)

If the fuel ratio is further reduced, the gas production of the final reduction is lower than the gas demand of the pre-reduction, which cannot meet the working parameters of the pre-reduction container. These problems hinder the further reduction of the fuel ratio

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