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Method for operating rotary heartn type reducing furnace and rotary hearth type reducing furnace facilities

A rotary furnace bottom and reduction furnace technology, applied to the operation of the rotary hearth reduction furnace and the field of rotary furnace bottom reduction furnace equipment, can solve the problem of heat exchanger blockage, insufficient prevention of adhesion, and inability to give sufficient powder components attention and other issues

Inactive Publication Date: 2004-02-11
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0016] Although the method disclosed in the aforementioned Japanese Patent Laid-Open No. 2000-169906 is an effective technique for preventing powder adhesion, it cannot sufficiently prevent the adhesion phenomenon especially when there are many alkali metal salts and zinc compounds.
In such conventional technologies, sufficient attention cannot be paid to the powder components in the exhaust gas, and the problem of clogging of the heat exchanger for heat recovery of the exhaust gas cannot be sufficiently solved.

Method used

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  • Method for operating rotary heartn type reducing furnace and rotary hearth type reducing furnace facilities
  • Method for operating rotary heartn type reducing furnace and rotary hearth type reducing furnace facilities
  • Method for operating rotary heartn type reducing furnace and rotary hearth type reducing furnace facilities

Examples

Experimental program
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Effect test

Embodiment 1～ Embodiment 3 and comparative example 1

[0084] exist figure 1 In the reduction furnace of the rotary furnace bottom processing method shown, powdered coke is mixed with powdered iron ore, electric furnace powder and finely powdered rolling scale to produce green pellets of 10-20mm, and the Restore it in the furnace. The hearth of the rotary furnace has a central diameter of 17 m and a hearth width of 4 m, and has a capacity of producing 15 tons of reduced iron per hour. The reduction zone 19 of the rotary kiln has a length of 35 m and the length of the heating zone 18 is 18 m. The results of the operation using this equipment are shown in Table 1. In addition, in Examples 1, 2 and Comparative Example, the amount of combustion gas generated is 27000 to 30000 Nm 3 / hour, while in Example 3, the amount of generation is 17000Nm 3 / Hour. In Example 1, the temperature of the reduction zone of the rotary kiln 1 was 1270° C., and the molar ratio of carbon monoxide to carbon dioxide was 0.55. The green pellets are redu...

Embodiment 4～ Embodiment 6 and comparative example 2

[0092] figure 1 It is an exhaust gas treatment facility of a reduction furnace performed by a rotary hearth used in Examples 4 to 6 and Comparative Example 2 of the working method of the present invention. The reduction furnace reduces 18 tons of green pellets as a raw material per hour, and the exhaust gas at 1100°C produces 45000Nm per hour 3 . Table 2 shows the operating conditions and results of Examples and Comparative Examples.

[0093] Example 1

Embodiment 6

[0094]In Example 6, the composition of the raw material or powder was within the scope of the present invention, but the temperature of the exhaust gas in the exhaust gas treatment system was not the result of operating under good conditions despite the method of the present invention. In addition, the same raw material as Example 5 was used as a raw material. Index 1 and Index 2 are the same as in Example 5. However, the temperature of the exhaust gas at the inlet of the exhaust gas outlet passage 2 is low at 760°C, and the temperature of the exhaust gas at the inlet of the heat exchanger 5 is high at 570°C. As a result, slight powder adhesion problems can occur in the exhaust gas treatment system. At the overhaul after 3 months of operation, it was confirmed that there was attachment at the entrance of exhaust gas outlet channel 2. Also, the inlet of the heat exchanger 5 is gradually clogged and must be cleaned after 2 months.

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Abstract

The present invention provides a method of operation and a facility for the same suppressing the generation of dioxins in the combustion exhaust gas and efficiently reclaiming heat from high temperature combustion exhaust gas when firing and reducing fines of chromium ore, iron ore, or other ore or pellets formed from dust sludge, etc. containing iron oxide or other metal oxides generated in the metal industry in a reducing rotary hearth furnace. This treats the combustion gas generated in the reducing rotary hearth furnace to make the temperature of the gas 800 DEG C. or higher for at least a certain time, to make the concentration of the carbon monoxide not more than 200 ppm in terms of volume ratio and to achieve a sufficiently well developed turbulent state at least at one of the inside of the exhaust gas outlet duct and the vicinity of the exhaust gas outlet duct for at least a certain time, then rapidly cooling the gas. Further, it controls the total number of moles of zinc and lead, the total number of moles of alkali metals, and the total number of moles of halogen elements contained in the combustion exhaust gas to a predetermined ratio.

Description

technical field [0001] The present invention relates to an operation method and its equipment for appropriately treating combustion exhaust gas. In a reduction furnace such as a rotary hearth type reduction furnace, when moldings such as pellets (pellets) containing oxidized metals are heated and sintered for reduction , can suppress the formation of dioxins in the combustion exhaust gas of the reduction furnace, and at the same time, can effectively perform heat exchange and heat recovery on the high-temperature combustion exhaust gas. Background technique [0002] There are many processing methods for producing reduced iron or alloy iron. Among them, there is a Wiltz-type rotary furnace (Wiltz-type rotary furnace) processing method in which a reducing agent and carbon are rotated inside a rotary kiln for heat reduction, or a rotary furnace bottom type Rotary furnace bottom processing method for sintering reduction in a reduction furnace. Among them, as a high-productivity...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21B13/00C21B13/10C22B5/10F27B9/16F27D17/00
CPCF27B9/16C22B5/10F27D17/004C21B13/105C21B13/10C21B13/0073C21B2100/44C21B2100/66Y02P10/134Y02P10/20F27D17/00Y02P10/25
Inventor 茨城哲治织田博史高桥政治
Owner NIPPON STEEL CORP
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