Increasing blast furnace top pressure is one of the technical measures to optimize blast furnace operation.
At present, high furnaces with different volumes in our country generally increase the top pressure to obtain benefits. Blast furnace top gas pressure greater than 0.03 MPa is called high pressure operation. After changing from normal pressure to 80kPa high pressure, the blast volume can be increased by 10%-15%, which is equivalent to increasing the air volume by 2%; after increasing the pressure again, the increased air volume is 1.7%-1.8%; when the blast furnace top pressure reaches 80kpa, it can be Promote the TRT operation of blast furnace top gas pressure differential power generation equipment; when the blast furnace top pressure reaches 120kPa, the operation of TRT equipment will be beneficial; the higher the furnace top pressure, the higher the benefits (including ironmaking indicators, TRT power generation) will be.
When the blast furnace gas adopts the dry dust removal technology, the TRT power generation can be increased by 30%. When the top pressure is increased by 10kPa, the blast furnace can increase production by (1.0±0.2)%, and the coke reduction ratio is 0.3%-0.5%, which is conducive to smelting low-Si iron, improving TRT power generation capacity, and reducing the content of furnace dust in gas. High pressure operation is not conducive to the reduction of SiO2 in the charge, and strengthens the carburizing process of smelting, so it is beneficial to the smelting of low-silicon ferrosilicon in the blast furnace, and to a certain extent, the coke ratio of ironmaking is reduced.
In high-pressure operation, the gas volume should be reduced, the gas flow rate will be reduced, and the head loss will be reduced, which is conducive to the full transfer of the gas heat to the charge, promotes the blast furnace to move forward and saves energy, and allows the ironmaking blast to increase the air volume by 2.5%-3.0%, and promotes pig iron production. 's elevation.
The main effects of high pressure operation on ironmaking production are as follows.
(1) The kinetic energy of blast furnace blast is reduced, the fuel combustion speed is accelerated, and the combustion zone in the blast furnace tuyere area is reduced, which is conducive to the reasonable distribution of gas flow, which can increase the air volume and increase the output of pig iron.
(2) Inhibit the development of direct reduction of iron ore, or push the direct reduction to high temperature area, which is beneficial to the reduction of iron ore by CO and improves the utilization of chemical energy of coal gas.
(3) The high pressure operation is not good for the reduction of Si in the charge; it strengthens the smelting and carburizing process.
(4) After high pressure operation, the resistance of the material column to the gas decreases; for every 100kPa furnace top pressure increase, the resistance loss of the material column decreases by 3kPa; from the normal pressure to the high pressure of 80kPa, the blast air volume can be increased by 10%-15%; Baosteel Production practice has proved that the blast furnace blast air volume can increase by 200-250m3/min for every 10kPa increase in the top pressure.
(5) After high pressure operation, the particle size and quantity of dust blown out in the gas become smaller. When the top pressure reaches 150-250kPa, the amount of dust blowing in the gas is below 10kg/t iron; it is manifested as thickening of the material layer at the edge of the charge and deepening of the funnel on the top surface; increasing the blast furnace top pressure, the gas flow rate in the blast furnace decreases. , so that the dust blowing is greatly reduced.
(6) For every 10kPa increase in blast furnace top pressure, the ironmaking fuel ratio decreases by 0.2%-1.5%.
(7) High pressure operation can improve the forward run of blast furnace production, reduce the overhang and collapse of iron production, increase the output, reduce the heat loss per unit of pig iron, and also create conditions for increasing the air temperature.
(8) Increasing the furnace top pressure is beneficial to increase the power generation of the TRT equipment. In a word, the high top pressure operation of high furnace can obtain excellent technical and economic indicators of blast furnace, high efficiency and large ironmaking benefit.