Metallurgical apparatus – Process
Reexamination Certificate
1997-09-24
2001-03-13
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
C266S155000, C266S156000
Reexamination Certificate
active
06200518
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a melt-reducing facility for directly producing molten iron or molten pig iron by throwing iron bearing material, carbon material and flux into a melt-reducing furnace and blowing pure oxygen and/or an oxygen-rich gas thereinto, and to a method of operation thereof.
BACKGROUND ART
The melt-reduction is a method of directly producing molten iron or molten pig iron by throwing iron bearing material, carbon material and flux into a furnace body, blowing pure oxygen and/or an oxygen-rich gas thereinto, and reducing iron oxides of the iron bearing material in the slag. According to this method, combustible gases at temperatures as high as about 1600 to 1800° C. are produced from the melt-reducing furnace.
In general, the method of melt-reduction of this kind can be divided into a two-stage method according to which pre-reduced iron bearing material, carbon material and flux are thrown into the furnace body, and the iron ore is pre-reduced with a CO gas and an H
2
gas contained in the combustible gases generated from the furnace body, and a single-stage method according to which unreduced iron bearing material, carbon material and flux are thrown into the furnace body, iron oxides in the iron bearing material are reduced in the slag, a CO gas and an H
2
gas in the combustible gases generated from the furnace body are completely burned in a waste heat boiler, and the sensible heat and the latent heat of the combustible gases are recovered by vaporization to generate. electricity (see, for example, Japanese Unexamined Patent Publications (Kokai) No. 1-502276, No. 63-65011, No. 63-65007, etc.).
The two-stage method has an advantage of better energy efficiency than the single-stage method, but requires a pre-reducing furnace such as of a packed bed type or a fluidized bed type, causing the facility to become complex, requiring an increased investment for the facility, and imposing limitation on the shape of iron bearing material due to uniform reaction in the pre-reducing furnace (e.g., the packed bed system permits the use of massive iron bearing material only, and the fluidized bed system permits the use of powdery iron bearing material only). In recent years, therefore, a simple single-stage method has drawn attention.
It has been widely known that in the single-stage method, the energy efficiency is improved, i.e., the unit requirement of carbon material is decreased by increasing the rate of combustion of CO gas and H
2
gas generated in the slag (hereinafter referred to as secondary combustion rate in the furnace, which is defined to be (CO
2
%+H
2
O%)/(CO
2
%+CO%+H
2
O%+H
2
%)) in a space in the furnace over the slag to effectively transmit the heat of combustion to the slag, and that the amount of heat of the combustible gases, i.e., the sum of the sensible heat and the latent heat generated from the furnace body, decreases by an amount by which the unit requirement of carbon material is decreased.
In the single-stage method as shown in
FIG. 4
, what is important is to compensate for the energy efficiency which is inferior to that of the two-stage method by recovering by vaporization the sensible heat and the latent heat of combustible gases generated in large amounts from the furnace body to generate electric power which can be sold to the utility or which can be used in other facilities in the factory, contributing to decreasing the amount of electric power that must be purchased.
In order to repair furnace body refractories of the melt-reducing furnace, however, the operation must be halted at regular intervals, e.g., once in three to twelve months as shown in FIG.
5
. That is, no electricity is generated during the period in which the operation is halted leaving a problem from the standpoint of stably supplying electric power. For example, when the electric power is to be sold to the utility, the price must be set low or when the electric power is to be used in other facilities in the factory, operation of the other facilities in the factory is interrupted.
The present invention was accomplished in order to solve the above-mentioned problems, and its object is to stably supply the electric power even when the operation is regularly halted in order to repair furnace body refractories in the melt-reducing furnace.
DISCLOSURE OF THE INVENTION
The present invention is concerned with a melt-reducing facility for directly producing molten iron or molten pig iron by throwing iron bearing material, carbon material and flux into furnace bodies and blowing pure oxygen and/or an oxygen-rich gas thereinto, wherein a waste heat boiler and a power-generating facility are connected to a plurality of furnace bodies through ducts which can be freely opened and closed, the waste heat boiler being capable of recovering by vaporization the sensible heat and the latent heat of the combustible gases generated from the furnace bodies. The invention is further concerned with a method of operating the melt-reducing facility wherein when, for example, two furnaces are being operated, the secondary combustion rate in the furnaces is increased to decrease the amount of heat of the combustible gases per a furnace and when one furnace is being operated, the secondary combustion rate in the furnace is decreased to double the amount of heat of the combustible gases in one furnace, so that the amount of heat of when one furnace is operated becomes the same as the total amount of heat of the combustible gases of the two furnaces.
That is, in the melt-reducing furnace of the present invention, a plurality of furnaces, e.g., two furnaces, furnace A and furnace B, are normally operated. When the operation of the furnace A is halted for repairing, the furnace B only is operated. When the operation of the furnace B is halted for repairing, the furnace A only is operated. Thus, the electric power generated by utilizing the waste heat is continuously supplied without being interrupted.
When both the furnace A and the furnace B are normally operated, the secondary combustion rate in the furnace is increased to decrease the amount of heat of the combustible gases per a furnace. When the furnace A only or the furnace B only is operated, the secondary combustion rate in the furnace is decreased to double the amount of heat of the combustible gases in the furnace, so that the amount of heat becomes the same as the total amount of heat of the combustible gases of the two furnaces. It is thus made possible to constantly supply the electric power by utilizing waste heat.
REFERENCES:
patent: 3060014 (1962-10-01), Aihara
patent: 3320931 (1967-05-01), Durham
patent: 3985544 (1976-10-01), Collin et al.
patent: 4451291 (1984-05-01), Leiponen
patent: 3 33 42 21 (1985-03-01), None
patent: 35 487 (1981-09-01), None
patent: 63-65011 (1988-03-01), None
patent: 63-65007 (1988-03-01), None
patent: 1-502276 (1989-08-01), None
patent: 4-311632 (1992-11-01), None
patent: 8-28353 (1996-01-01), None
Patent Abstracts of Japan, vol. 13, No. 379 (C-628), Aug. 22, 1989 & JP 01 129914 A (Kawasaki Heavy Ind), May 23, 1989.
Kastler Scott
Kenyon & Kenyon
Nippon Steel Corporation
LandOfFree
Melt-reducing facility and method of operation thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Melt-reducing facility and method of operation thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Melt-reducing facility and method of operation thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445445