Nippon Steel Corporation

Nippon Steel Engineering Co., Ltd.

Nittetsu Plant Designing Corporation

Shinji Shima

Tomoaki Shibata

Toshitaka Nakayama

Masahide Nagatomi

Yuichi Sakurai

The present invention discovers a new structural design technique which provides clearances between refractoriesand fills the clearances with various types of refractories or refractory materials like in the past and, furthermore, uses another method to secure the heat expansion absorption function and provides a hearth structure of a rotary furnace hearthable to prevent contact between the hearth structure and furnace side wallsandcaused by heat expansion of the refractoriesand realize safe and smooth operation, that is, a hearth structure of a rotary furnace hearth laying two or more layers of refractories between side blocksandbuilt at the inner circumferential end and outer circumferential end of a hearth refractory bedof a rotary furnace hearthand laying a powder or pellet hearth materialon its top surface, the hearth structure of a rotary furnace hearthcharacterized by using refractories having a compressive strength of 0.1 to 5 MPa at 800 to 1500&#xb0; C. for the refractorieslaid at least at the topmost layer.

Hearth structure of rotary furnace hearth

A rotary furnace hearth wherein a hearth carriage carrying a hearth comprises a plurality of hearth carriages respectively having propulsion systems, wherein adjoining hearth carriages are coupled by coupling bolts and nuts via spacers interspaced in a single row in a horizontal plane, whereby even if the hearth carriages deform due to heat at the time of operation, they are structured to be able to freely deform without mutual constraint in the event of curved deformation, so the hearth carriages are maintained in individually stable states at all times.

Hearth carriage coupling structure of rotary furnace hearth

A reduced iron discharging screw conveyer is provided in a rotary hearth furnace and discharges reduced iron out of the rotary hearth furnace. The rotary hearth furnace produces the reduced iron by charging and heating a pellet including metallic oxide and coal material onto a rotary hearth rotating in a horizontal plane. The reduced iron discharging screw conveyer has a rotary shaft and a screw blade which is spirally formed on an outer surface of the rotary shaft. A lead angle &#x3b8; of the screw bladesatisfies a condition of '0.46 rad &#x2266;&#x3b8;&#x2266;0.79 rad'. A ratio (h/D) between height h of the screw blade and an outer diameter D of the screw conveyer is smaller than 0.2, and a ratio (t/h) between thickness t and height h of the screw blade is larger than or equal to 0.12.

Screw conveyor of rotary hearth furnace for discharging reduced iron

A furnace sidewall structure of a rotary hearth furnace for making direct reduced iron which is agglomerated iron ore or waste iron oxide containing a reducing agent on a rotary hearth by heating or for heating at least one steel piece, wherein the rotary hearth furnace includes an outer furnace sidewall and an inner furnace sidewall, wherein at least one of the outer furnace sidewall and the inner furnace sidewall is polygonal. The furnace sidewall structure can be prepared with lower manufacturing costs relative to conventional circular profile rotary hearth furnace with respect to the furnace sidewall. The production thereof is easy with respect to manufacturing and with respect to the fact that the dimensional accuracy of the manufactured furnace sidewall can be easily adjusted. Also, there is associated a shorter installation/construction work period and a reduction in the installation/construction cost.

Furnace sidewall structure of rotary hearth furnace

The invention provides a raw materials feeding apparatus capable of uniformly dispersing and feeding into a furnace agglomerated raw materials that are likely to undergo dusting, deformation and mutual adhesion. In a raw material feeding apparatus for a rotary hearth furnace, for feeding raw materials to a rotary hearth furnace by using a flat belt conveyor, the invention employs a construction in which a scraper for guiding the raw materials on the flat belt conveyor to a side surface of the flat belt conveyor is arranged obliquely to a traveling direction of the flat belt conveyor. Preferably, the scraper is arranged in such a manner as to guide the raw materials to both sides of the flat belt conveyor.

Growing community of inventors

Kitakyushu, Japan

Shinji Shima