Method for producing direct reduced iron with limited CO2 emissions

An apparatus for producing direct reduced iron, DRI, in a direct reduction system comprising

• a moving bed reduction reactor with a reduction zone and a lower discharge zone,
• a gas cooling unit,
• a selective carbon dioxide removal unit, and
• a reducing gas heater, all connected together to form
• a reducing gas recycle loop,
• said reducing gas heater having burners,
• said reactor being capable of use for the reduction of iron-oxides-containing particles to DRI containing metallic iron, by reaction with a high temperature reducing gas mainly composed of hydrogen and carbon monoxide derived from a hydrocarbon-containing gas;
• said gas cooling unit being capable of cleaning and cooling spent gas effluent from said reactor comprising hydrogen, carbon monoxide, carbon dioxide, methane and water, whereby water is condensed and withdrawn from said spent gas;
• said selective carbon dioxide removal unit being capable of treating such cleaned and cooled reducing gas to produce a stream of almost pure carbon dioxide which can be controllably withdrawn from the reduction plant, thus producing an upgraded reducing gas, mainly comprised of hydrogen, carbon monoxide and methane;
• said reducing gas heater being capable of heating a first portion of said upgraded reducing gas to be recycled via said recycle loop back into said reactor after being heated;
• and
• a gas source capable of supplying hydrocarbon-containing gas available to be reformed to H2 and CO as make up gas;
• said apparatus comprising
• a physical gas separation unit capable of separating a gas containing carbon monoxide, methane, and hydrogen into separate streams of gas with a first stream having a higher concentration of hydrogen and a second stream having a higher concentration of carbon monoxide and methane and being connected to said reducing gas recycle loop between said selective carbon dioxide removal unit and said reducing gas heater and thus being capable of receiving and treating a second portion of said upgraded reducing gas from said reducing gas recycle loop to produce the first gas stream and the second gas stream;
• said physical gas separation unit being connected to the burners of said reducing gas heater to be capable of supplying said first gas stream as fuel to said burners, and
• said physical gas separation unit being connected back to said reducing gas recycle loop to be capable of recycling said second gas stream back into said reducing gas recycle loop towards said reducing gas heater to eventually be treated in said selective carbon dioxide removal unit, whereby the combustion of said hydrogen-containing first gas stream in the process gas heater in substitution of carbon-bearing fuels, decreases the carbon dioxide emissions to the atmosphere of said reduction plant.