What are the measures to improve the ironmaking utilization rate of square and rectangular tube?

1. Increase CO2 content

It adopts material less bell top loading equipment to realize various forms of material distribution. The distribution of gas flow is divided into three distributions: the air supply from the tuyere is the first time, the control of the small blast furnace is greater than 100m/s, and the large blast furnace is at 180-220m/s; the reflow zone is the second distribution, and the control of the reflow temperature is higher, the interval should be narrow to reduce gas resistance; the charge above the reflow zone is the third time. The overall realization is that there are two gas streams at the edge and the center. Generally, for every 1% increase in CO2 content in the gas, the energy consumption of the ironmaking process is reduced by 17kgce/t.

2. Low-silicon ferro-smelting

Square and rectangular tube lower the theoretical combustion temperature before the tuyeres during the operation of the blast furnace, the temperature of the molten iron is kept at about 1450°C, and the basicity of the slag is selected to avoid the generation of short slag as much as possible when the furnace temperature fluctuates. Usually, the Si content in pig iron is reduced by 0.1%, which can reduce the ironmaking coke ratio by 4-5kg/t.

3. Achieve high wind temperature

The measures to achieve high air temperature are to make the top temperature of the hot blast stove higher than 1400°C, adopt high-temperature-resistant silica bricks for the vault, separate the vault from the large wall, increase the heat storage area with 19-30 hole bricks, and use air and gas double warm-up technique, etc. Every 100°C increase in hot air temperature can reduce the ironmaking fuel ratio by 15-25kg/t, and increase the theoretical combustion temperature of the tuyere by 60°C, which brings great convenience to the production of square and rectangular tube.

4. Dehumidification blast

In the production of square and rectangular tube, it is necessary to control the blast furnace blast humidity to 6g/m3 and keep it stable. Usually, the humidity blast is reduced by 01%, which can reduce the coke ratio of ironmaking by 0.9%, and increase the production by 3.2%.

5. High-pressure technology

After the blast furnace top gas is increased, the blast furnace reaction will be smoother, the ore indirect reaction will be more favorable, and CO will easily be converted into CO2. When the gas pressure at the top of the blast furnace is greater than 0.03mpa, it becomes high pressure. For every 10kpa increase in furnace top gas pressure, the blast furnace can increase production by 1.9%.