Method for supplying hydrogen-containing reducing gas to shaft part of blast furnace
The present invention provides a novel method for supplying a reducing gas to the shaft part of a blast furnace with which a large amount of reducing gas containing hydrogen at a high concentration can be supplied to a deeper position in the blast furnace (location of the blast furnace closer to the center axis in the radial direction) and with which it is possible to reduce the total generated amount of CO 2 of the CO 2 amount that is reduced by conducting hydrogen smelting in the blast furnace and the CO 2 amount that is generated during production of the reducing gas supplied to the blast furnace. The method for supplying a reducing gas to the shaft part of a blast furnace according to the present invention is characterized by reforming coke oven gas by increasing the temperature thereof to 1200 to 1800° C. in a reactor in which an oxygen-containing gas is supplied to preheated coke oven gas to generate reformed gas in which hydrogen gas is enriched; mixing the reformed gas with CO-containing gas in the reactor so that the hydrogen concentration of the reducing gas is adjusted to 15-35 vol % (wet); and supplying the resultant reducing gas to the shaft part of the blast furnace under a condition of a ratio of a flow rate of reducing gas blown into shaft part/flow rate of reducing gas blown into tuyere >0.42.
1. A method for supplying a hydrogen-containing reducing gas to a shaft part of a blast furnace, the method comprising manufacturing the hydrogen-containing reducing gas by raising a temperature inside a reactor in which an oxygen-containing gas is supplied to a preheated coke oven gas to 1200 to 1800° C. to reform the coke oven gas and thereby produce reformed gas enriched in hydrogen gas, then mixing a CO-containing gas with that reformed gas in the reactor to adjust a concentration of hydrogen to 15 to 35 vol % (wet) and supplying the hydrogen-containing reducing gas to the shaft part of the blast furnace under a condition of a ratio of a flow rate of blowing the hydrogen-containing reducing gas to the shaft part/a flow rate of blowing an air and/or oxygen to a tuyere>0.42.
2. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 1 wherein the oxygen-containing gas is oxygen gas and the method of reforming the gas by raising the temperature in the reactor to 1200 to 1800° C. is partial oxidation of the preheated coke oven gas.
3. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 1 wherein the oxygen-containing gas is steam produced by combustion of hydrocarbons and the method of reforming the gas by raising the temperature in the reactor to 1200 to 1800° C. is mixing combustion gas of the hydrocarbons with the preheated coke oven gas.
4. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 1 , further comprising:
a) a step of raising a pressure of the coke oven gas,
b) a step of adjusting a flow rate of the coke oven gas,
c) a step of preheating the coke oven gas, and
d) a step of raising the temperature of the preheated coke oven gas inside the reactor in which oxygen gas is supplied to 1200 to 1800° C. and reforming the coke oven gas by partial oxidation to produce reformed gas enriched in hydrogen gas, then mixing into that reformed gas the CO-containing gas in the reactor to adjust the concentration of hydrogen of the reformed gas to 15 to 35 vol % (wet) and the temperature to 800 to 1000° C. to produce reforming-use hydrogen gas for supplying to the shaft part of the blast furnace.
5. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein a concentration of CO in the CO-containing gas is 50 vol % to less than 99 vol % (dry), a concentration of CO 2 is 0 vol % (dry) to less than 1 vol % (dry), a concentration of H 2 is 0 vol % (dry) to less than 35 vol % (dry), and a concentration of N 2 is 1 vol % (dry) to less than 20 vol % (dry).
6. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein the CO-containing gas is blast furnace gas, converter gas, or synthesis gas treated to remove CO 2 .
7. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein the hydrogen-enriched reformed gas contains a hydrocarbon gas in an amount of 1% to 5%.
8. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein a flow rate of supply (mol/s) of the oxygen gas is 0.4 to less than 0.5 time a flow rate of supply (mol/s) of carbon atoms contained in the hydrocarbons in the coke oven gas.
9. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein as the coke oven gas, reformed coke oven gas obtained by treating crude coke oven gas, obtained from a coke oven that reduces a moisture in crude coke oven gas emitted, in a carbonization furnace held at 700° C. or more to break down the hydrocarbons in the crude coke oven gas is used.
10. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 4 , wherein the step of raising the pressure of the coke oven gas and the step of adjusting the flow rate of the coke oven gas are performed in that order or in reverse order before the step of preheating the coke oven gas.
11. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 1 , further comprising
a) a step of running coke oven gas from the coke oven through a carbonization furnace and breaking down hydrocarbons in the coke oven gas into coke and hydrogen to thereby make a concentration of hydrogen increase,
b) a step of removing a tar and at least part of a moisture in the gas run through the carbonization furnace to manufacture a first reformed gas,
c) a step of raising a pressure of the first reformed gas,
d) a step of preheating the raised pressure first reformed gas,
e) a step of supplying the preheated first reformed gas to a partial oxidation reforming apparatus and supplying combustion gas to that partial oxidation reforming apparatus to further reform the hydrocarbons in the first reformed gas to make the concentration of hydrogen increase to manufacture a second reformed gas, and
f) a step of supplying the second reformed gas from a gas supply port leading to the shaft part of the blast furnace to an inside of the blast furnace.
12. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 11 , further comprising raising the pressure of the first reformed gas to at least 0.2 MPa in pressure.
13. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 11 , further comprising preheating the first reformed gas to 800° C. to 1000° C.
14. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 11 , further comprising supplying combustion gas to the partial oxidation reforming apparatus by
(i) supplying combustion gas obtained by supplying oxygen gas and flammable gas to a burner,
(ii) supplying oxygen gas and flammable gas to the partial oxidation reforming apparatus to generate combustion gas inside that partial oxidation reforming apparatus and supplying the same, or
(iii) supplying oxygen gas to the inside of the partial oxidation reforming apparatus to make part of the first reformed gas burn and supplying the same.
15. The method for supplying hydrogen-containing reducing gas to a shaft part of a blast furnace according to claim 11 , further comprising, before preheating the first reformed gas, temporarily holding the raised pressure gas in a gas holder and further raising the pressure of the gas from this gas holder.