A method for converting a blast furnace plant for synthesis gas utilization includes:

constructing a syngas stove, and constructing a syngas supply system for connecting the syngas stove to a blast furnace;

connecting a first syngas stove to the top-gas supply system, the cold-blast and hot-blast supply systems and operating the first syngas stove for hot blast generation;

disconnecting a first original stove from the top-gas supply system, the cold-blast and hot-blast supply systems; and

converting the first original stove to adapt it for producing syngas. The method includes

connecting the first original stove to the top-gas supply system;

disconnecting the first syngas stove from the cold-blast and hot-blast supply systems, connecting the first original stove and first syngas stove to a gas-combination supply system; and

operating the first original stove and first syngas stove to produce and then supply syngas to the blast furnace via the syngas supply system.

According to a certain viewpoint of the present invention, there is provided a blast furnace operation method comprising blowing a high-concentration hydrogen-containing gas containing 80 mol % or more of hydrogen gas from a tuyere under: a condition in which a blowing temperature of the high-concentration hydrogen-containing gas is room temperature or higher and 300° C. or lower and a gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 200 Nm.sup.3/t or more and 500 Nm.sup.3/t or less; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 300° C. and 600° C. or lower and the gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 145 Nm.sup.3/t or more; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600° C. and 900° C. or lower and the gas volume of the high-concentration hydrogen-containing gas is 125 Nm.sup.3/t or more, or the like.

A method for producing direct reduced iron is provided. The method includes circulating a first stream of spent reducing gas exiting a reactor in a reducing gas circuit through at least one carbon dioxide removal unit and a reducing gas heater and the reactor. The method also includes mixing the first stream with reducing gas containing heavier hydrocarbons than methane.

Provided is a method of operating a blast furnace, having generating a regenerative methane gas from a by-product gas discharged from the blast furnace, and blowing a blast gas and a reducing agent into the blast furnace from a tuyere of the blast furnace in which the blast gas is oxygen gas and the regenerative methane gas is used as at least part of the reducing agent.

A system and method of direct reduction of iron (DRI) is disclosed, having a reduction unit configured to reduce iron oxides to metallic iron; a process gas heater coupled to the reduction unit, the process gas heater configured to supply the reduction unit directly with a source of heated reducing gas, where the process gas heater is further configured to receive a synthetic combustion air stream for heating the reducing gas, the synthetic combustion air stream comprising a source of oxygen with essentially no nitrogen. A method of carbon dioxide emission reduction from a direct reduction of iron (DRI) process is also disclosed.

A method for measuring the softening and melting performances of iron ore in blast furnace is disclosed, which is implemented by a device including a high temperature furnace, gas supply system, a loading system and a weighing system. The method includes: step 1: the dried coke and iron ore specimen are placed in the graphite crucible in a specified way; step 2: the graphite crucible is placed in the high temperature furnace, and N.sub.2 is continuously fed into the high temperature furnace to reach an airtightness requirement; step 3: a vacuum pump is used to extract mixed gas in a hearth of the high temperature furnace and heating process is started; step 4: both the composition of mixed gas and pressure imposed on the iron ore are controlled according to the designed temperature variation; step 5: data are acquired to calculate.

Provided is a method of operating a blast furnace, including generating a regenerative methane gas using a blast furnace by-product gas, and blowing a blast gas and a reducing agent into the blast furnace from a tuyere, in which the blast gas is oxygen gas, the regenerative methane gas is used as at least part of the reducing agent, and the oxygen gas and/or the regenerative methane gas is preheated before being blown into the blast furnace from the tuyere.

Provided is a solid carbon production facility including: a separation facility configured to separate a carbon dioxide gas contained in a produced gas produced by a blast furnace; a reaction facility configured to heat a fuel gas whose main component is a methane gas by using a heating facility and decompose the methane gas into solid carbon and a hydrogen gas; and a production facility configured to cause the carbon dioxide gas separated by the separation facility and the hydrogen gas decomposed by the reaction facility to react with each other to produce solid carbon and water.

Provided is a steelmaking line contributing to the realization of a method that achieves energy saving and CO.sub.2 emission reduction when producing reduced iron from iron oxide. The steelmaking line comprises: a blast furnace configured to reduce iron oxide; a reducing furnace configured to reduce iron oxide; a methane synthesizer configured to synthesize methane from blast furnace gas and/or furnace top gas, and hydrogen gas; a blower configured to blow the methane gas synthesized by the methane synthesizer into the blast furnace; a heat-reformer configured to heat or heat-reform the blast furnace gas and/or the furnace top gas, and the methane gas synthesized by the methane synthesizer, to generate reducing gas; a reducing gas blower configured to blow the reducing gas into the reducing furnace; and a supply path configured to supply the furnace top gas to the methane synthesizer and/or the heat-reformer.

Systems for producing iron may include (a) a reactor configured to receive iron ore and a reducing gas, and from these produce iron; and (b) a carbon dioxide reduction electrolyzer configured to produce at least carbon monoxide and/or a hydrocarbon. Such systems may be configured to transport carbon dioxide produced by the reactor and/or produced by combustion of a gas generated by the reactor to a cathode side of the carbon dioxide reduction electrolyzer. Such systems may be further configured to transport at least a portion of the carbon monoxide and/or hydrocarbon produced by the carbon dioxide reduction electrolyzer to the reactor, where the carbon monoxide and/or hydrocarbon serves as at least a part of the reducing gas.