A Coal Injection System for Blast Furnace Ironmaking and Its Application Method

Abstract

A coal injection system for blast furnace ironmaking and a use method thereof, belonging to the field of green and efficient production of blast furnace ironmaking. The purpose is to dynamically control the burnout rate of pulverized coal through carbon dioxide transmission and coal injection. Using the inertness of carbon dioxide at room temperature, it can react with pulverized coal at the high temperature of the tuyere of the blast furnace to reduce the oxidation ablation and combustion temperature. The present invention adds a carbon dioxide gas source, a carbon dioxide gas valve, a carbon dioxide gas flow meter, a transport gas oxygen source, and an annular seam gas distribution bag to the original coal injection system. Carbon dioxide is used as the supplementary gas of the pulverized coal bunker and the fluidization gas of the coal injection tank, the mixed gas of carbon dioxide, oxygen and air is used as the pulverized coal delivery gas, and the mixed gas of carbon dioxide and oxygen is used as the annular seam gas of the coal injection gun, according to the amount of coal injection Different, run in different modes. In the present invention, while ensuring that the oxygen content in the transported gas is within a safe range, the oxygen equivalent of the transported gas is changed from 18.75mol / Nm to that of air 3 The highest can be increased to 54.02mol / Nm 3 , the air flow rate of a single coal injection gun annular seam is from 200 to 400Nm 3 / h up to 411.76~647.06Nm 3 / h, increase the burnout rate of pulverized coal by 0-8%.

Description

technical field [0001] The invention belongs to the field of green and high-efficiency blast furnace ironmaking, and relates to a coal injection system for blast furnace ironmaking and its use method. It can react with coal powder to reduce oxidation ablation and combustion temperature. Background technique [0002] Blast furnace coal injection technology replaces coke with pulverized coal to provide heat and reducing agent for ironmaking production, thereby reducing the coke ratio and pig iron cost. research focus. At present, the amount of coal injection in advanced blast furnaces at home and abroad is only 220-250kg / t, and it is difficult to further increase, mainly because the residence time of pulverized coal in the blast furnace tuyere is relatively short, about 0.2S. With the increase of coal injection, the pulverized coal The burnout rate will be significantly reduced, and the accumulation of unburned coal powder will lead to poor air permeability of the blast furn...

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Problems solved by technology

However, in this method, the pulverized coal and the oxygen in the outer layer are transported separately, because the mass transfer rate in the gas phase is not high, and the oxygen mixing efficiency is low in the limited residence time of the tuyere swirl zone, and the improvement effect on the pulverized coal burnout rate is limited; at the same time, the annular seam Oxygen injection has a strong oxidation and ablation effect on the steel pipe of the coal injection gun, and the oxygen flow rate is difficult to increase. Generally, the oxygen flow rate of a single coal injection gun ring seam is only 200-400Nm 3 / h, which limits the improvement effect of the technology even more

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