A process for producing reducing gas for use in the production of direct reduced iron (DRI) and fuel gas for use in a steel mill, including: compressing a coke oven gas (COG) stream in a compressor; passing the compressed coke oven gas stream through an activated charcoal bed to remove tars from the compressed coke oven gas stream; separating a hydrogen-rich gas stream from the compressed cleaned coke oven gas stream using a pressure swing absorption unit; providing the hydrogen-rich gas stream to a direct reduction shaft furnace as reducing gas; and providing a remaining gas stream from the pressure swing absorption unit to a steel mill as fuel gas. Both once-through and recycle options are presented. Optionally, basic oxygen furnace gas (BOFG) is added to the reducing gas.

A method for heating a blast furnace stove includes combusting a fuel with a lower heating value (LHV) of 9 MJ/Nm.sup.3 or less in a combustion zone which is arranged in a combustion chamber in the stove, and causing the combustion gases to flow through and thereby heat refractory material in the stove. The fuel is combusted with an oxidant including at least 85% oxygen, and combustion gases are recirculated into the combustion zone for diluting the mixture of fuel and oxidant therein sufficiently for the combustion to be flameless.

Methods and systems for producing DRI utilizing a petroleum refinery bottoms (i.e. heavy fuel oil, vacuum residue, visbreaker tar, asphalt, etc.) or petroleum coke gasifier and a hot gas cleaner. Cooling of the hot synthesis gas generated by the petroleum refinery bottoms or petroleum coke gasifier to <200 C is not necessary. Rather, the synthesis gas from the petroleum refinery bottoms or petroleum coke gasifier is desulfurized and dedusted at high temperature (>350 C) using a hot gas cleaner, well known to those of ordinary skill in the art, although not in such an application. This hot gas cleaner may be high pressure or low pressure.

The invention relates to a process for preparing ammonia gas and CO.sub.2 for urea synthesis. In the process of the invention, a process gas containing nitrogen, hydrogen and carbon dioxide as main components is produced from a metallurgical gas. The metallurgical gas consists of blast furnace gas, or contains blast furnace gas at least as a mixing component. The process gas is fractionated to give a gas stream containing the CO.sub.2 component and a gas mixture consisting primarily of N.sub.2 and H.sub.2. An ammonia gas suitable for the urea synthesis is produced from the gas mixture by means of ammonia synthesis. CO.sub.2 is branched off from the CO.sub.2-containing gas stream in a purity and amount suitable for the urea synthesis.

Methods and systems for producing direct reduced iron having increased carbon content, comprising: providing a reformed gas stream from a reformer; delivering the reformed gas stream to a carbon monoxide recovery unit to form a carbon monoxide-rich gas stream and a hydrogen-rich gas stream; and delivering the carbon-monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one of a transition zone and a cooling zone of the direct reduction furnace. Optionally, the method further comprises mixing the carbon monoxide-rich gas stream with a hydrocarbon-rich gas stream.

Provided are a joint regulation method of material flow, energy flow, and carbon emission flow in a long-process steel enterprise, which belongs to a field of intelligent regulation and control technology of electric power system in the steel industry. The method includes: coupling a material-energy characteristic model of each production process of a steel enterprise and a carbon emission model of the steel enterprise, constructing a material flow-energy flow-carbon emission flow coupling model of the long-process steel enterprise, establishing an objective function using a minimize sum of an electricity purchase cost from a superior grid, a park carbon emission cost, and a production raw material cost as an object, and solving and obtaining an optimal operation mode of a joint regulation of the material flow-energy flow-carbon emission flow in the steel enterprise.

According to embodiments, disclosed is a method and system to maintain the soft and sparse slag characteristic favorable for an electric arc to efficiently transfer the energy to molten iron with the power input per furnace area higher than 600 KW/m2 while keeping FeO amount less than 5% in the slag and carbon amount higher than 2.5% in the product hot metal at a DRI melting furnace.

Provided are a joint regulation method of material flow, energy flow, and carbon emission flow in a long-process steel enterprise, which belongs to a field of intelligent regulation and control technology of electric power system in the steel industry. The method includes: coupling a material-energy characteristic model of each production process of a steel enterprise and a carbon emission model of the steel enterprise, constructing a material flow-energy flow-carbon emission flow coupling model of the long-process steel enterprise, establishing an objective function using a minimize sum of an electricity purchase cost from a superior grid, a park carbon emission cost, and a production raw material cost as an object, and solving and obtaining an optimal operation mode of a joint regulation of the material flow-energy flow-carbon emission flow in the steel enterprise.

According to embodiments, disclosed is a method and system to maintain the soft and sparse slag characteristic favorable for an electric arc to efficiently transfer the energy to molten iron with the power input per furnace area higher than 600 KW/m2 while keeping FeO amount less than 5% in the slag and carbon amount higher than 2.5% in the product hot metal at a DRI melting furnace.