Blast furnace—converter steel production method based on carbon cycling
The present invention pertains to the field of steel smelting, specifically to a method for steel production in a blast furnace and a converter based on carbon cycling. The method comprises the following steps: 1. Smelting iron in a blast furnace to obtain molten iron; 2. Introducing the aforementioned molten iron into a converter and carrying out steel refining within the converter to obtain molten steel and untreated converter gas; 3. Subjecting the untreated converter gas to pressurisation, deoxygenation, dehydration, and decarbonisation treatments to obtain synthesis gas and treated converter gas; 4. Recycling the treated converter gas back into the blast furnace to regulate the ratio of reductive gases within the furnace atmosphere. Beneficial Effects: The method enables the cyclic utilisation of converter gas. By decarbonising the converter gas and recycling it back into the blast furnace, the content of reductive gases in the furnace atmosphere is enhanced. This promotes indirect reduction within the blast furnace while decreasing direct reduction, thereby reducing the consumption of carbonaceous fuel during the blast furnace iron smelting process and effectively lowering CO2 emissions.
1 . A method for steel production in a blast furnace and a converter based on carbon cycling, characterised by the following steps:
a) smelting iron in a blast furnace to obtain molten iron;
b) introducing said molten iron into a converter for steel refining to obtain molten steel and untreated converter gas;
c) subjecting the untreated converter gas to pressurisation, desulphurisation, deoxygenation, dehydration, decarbonisation, and denitrification sequentially to obtain synthesis gas and treated converter gas;
d) recycling the treated converter gas back into the blast furnace to regulate the ratio of reductive gases within the furnace atmosphere;
wherein the untreated converter gas contains a CO concentration of 40% or higher;
wherein step c) further comprises pressurising said untreated converter gas to 0.50 MPa~0.65 MPa via a gas pressurisation unit;
wherein in step c), prior to the desulphurisation process, the temperature of the pressurised converter gas is controlled between 60° C.~90° C. through a cooling unit;
wherein in step c), the desulphurisation and denitrification include reducing the sulphur content to less than 10 ppm through a desulphurisation unit, and achieving a denitrification efficiency of 90% or higher through a denitrification unit;
wherein in step c), the desulphurisation and denitrification include reducing the sulphur content to less than 10 ppm through a desulphurisation unit;
wherein in step c), the desulphurisation and denitrification include achieving a denitrification efficiency of 90% or higher through a denitrification unit;
wherein in step d), the recycling of treated converter gas back into the blast furnace includes heating the treated converter gas to 850° C.~950° C. through a gas heating unit; the heated converter gas is blown back into the blast furnace so that the fuel ratio is 433 kg/t.
2 . The method according to claim 1 , said method includes the pressurisation, deoxygenation, dehydration, and decarbonisation of untreated converter gas through:
c1) reducing the oxygen content to less than 1 ppm via a deoxygenation unit;
c2) achieving a dehydration efficiency greater than 95% via a dehydration unit;
c3) achieving a CO 2 removal rate of 95% or higher via a decarbonisation unit.
3 . The method according to claim 1 , the recycling of treated converter gas back into the blast furnace includes using a gas injection unit to direct the heated converter gas back into the blast furnace, where the injection nozzle is aimed at the furnace body and/or tuyeres.
4 . The method according to claim 3 , the heat required for gas heating is provided by the combustion of gas within the gas network, which includes blast furnace gas and/or synthesis gas.
5 . The method according to claim 3 , the decarbonisation treatment can be either dry or wet;
wherein when dry decarbonisation is used, the CO 2 concentration in the synthesis gas is ≤95%, and this synthesis gas is combined with the gas network connected to the blast furnace; and
when wet decarbonisation is employed, the CO 2 concentration in the synthesis gas exceeds 95%, and the synthesis gas undergoes carbon capture utilization, and storage (CCUS) treatment.