Method and apparatus for producing direct reduced iron with improved reducing gas utilization
AssigneeHylsa S.A. de C.V.
InventorJuan A. Villarreal-Trevino
Life of this patent
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Abstract
A method and apparatus for producing DRI, prereduced materials, or the like, utilized in the steelmaking industry, where hydrogen contained in the gas stream purged from the reduction reactor is separated (preferably by means of a PSA system) and recycled to said reduction reactor. The productivity of the reduction plant is increased by using the separated hydrogen as a chemical reductant in the reactor, instead of using it as fuel. This is particularly useful in upgrading existing DRI production plants.
Claims26
A method for producing direct reduced iron DRI or prereduced iron ore with improved reducing gas utilization, comprising:
- feeding a stream of reducing gas mainly composed of hydrogen and carbon monoxide and also comprising methane, carbon dioxide and water, heated at a temperature between about 750.degree. C. to about 1050.degree. C., to a reduction zone within a reduction reactor wherein solid particles containing iron oxides present therein are reduced by reaction of said iron oxides with said reducing gas;
- withdrawing from said reactor said reducing gas after reacting with said iron oxides as top gas;
- cooling and cleaning said top gas and removing water therefrom to produce a cooled top gas;
- heating and recycling a first portion of said cooled top gas to said reduction reactor as part of said stream of reducing gas;
- purging a second portion of said cooled top gas;
- adding make-up gas to gases eventually recycled to the reducing zone;
- separating from said second portion of said cooled top gas at least the majority of the hydrogen contained therein to form a hydrogen rich gas stream which is lean in carbon dioxide, and
- recycling said hydrogen rich gas stream to said reduction reactor.
An apparatus for producing prereduced materials, including DRI, with improved reducing gas utilization, comprising:
- a reduction reactor having a reduction zone with a gas inlet and a gas outlet;
- a gas cooler in fluid communication with the gas outlet of said reduction zone;
- a reducing gas heater in fluid communication with the gas inlet of said reduction zone;
- first pumping device connected to said cooler and to said heater to recycle reducing gas from said gas outlet to said gas inlet;
- conduit device for diverting a portion of the reducing gas effluent from said gas outlet of said reduction zone to second pumping device;
- a separating device for producing a hydrogen rich output and a hydrogen lean output with the carbon dioxide content;
- a conduit device communicating said second pumping device to said separating device;
- and
- a conduit device to communicate from said hydrogen rich output of the separating device to between said first pumping device and the gas inlet of said reduction zone.
Dependencies are inferred from the claim text.