JPS6318016A - Method and equipment for melting iron-based scrap - Google Patents

Abstract

PURPOSE:To melt scrap with good thermal efficiency by lifting cold charge scrap from the lower part of a shaft furnace connecting in the upper part to an exhaust gas pipe of a heating furnace and preheating the same by the high- temp. exhaust gas of the heating furnace, then supplying the scrap to the heating furnace at the time of melting the ferrous scrap. CONSTITUTION:The ferrous scrap 19 such as steel scrap is continuously supplied into the shaft furnace 11 from a lower inlet 14 thereof and is lifted in the shaft furnace 11 by a cylinder 25. The scrap is heated by the high-temp. exhaust gas from the heating furnace 16 in the mid-way thereof. Fuel of gas and liquid, air, oxygen, etc., are blown from a blow pipe 24 into the furnace and the CO in the fuel and exhaust gas is burned. The scrap is heated to >=1,400 deg.C by the heat thereof and the scrap is lifted onto the top of the shaft furnace 11. The high-temp. scrap 19 is supplied into the heating furnace 16 by an ejecting cylinder 18. Pulverized coal, oxygen, CaO as a slag forming agent, etc., are blown from furnace bottom tuyeres into a molten metal to melt the falling high-temp. scrap. The exhaust gas decreased in temp. after heating the cold charge scrap is discharged from an exhaust gas pipe 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for melting iron-based scrap and an improvement in a melting apparatus for the same.

(Prior Art) Various processes using a converter-type melting furnace have been reported as conventional iron-based scrap melting processes using carbonaceous materials such as coal as a fuel source. In this method, iron-based scrap is inserted into a converter, coke and pulverized coal are blown in from the bottom of the converter along with oxygen, and oxygen is blown in from the top of the converter to melt the ferrous scrap. However, this method requires a relatively large amount of coke, etc., and is expensive. Additionally, because the furnace is operated in batch mode due to its structure, there is a problem with operational efficiency.

In the known shaft furnace 1 shown in FIG. 2, iron-based scrap 3 is charged at a constant rate from a hopper 2 placed at the top, and then high-temperature gas generated from a melting reactor 4 is supplied from the top of the shaft furnace 1 to fill the furnace. After that, the Rosdol type damper is opened and the iron scrap is put into the melting furnace 6, where oxygen, pulverized coal, argon, etc. are blown into the iron scrap. is dissolved.

However, this method is a batch method and cannot be operated continuously.

Moreover, a heat-resistant Rossdol type damper 5 is required to hold the raw material, but there is no damper made of a material that can withstand the high temperatures of a shaft furnace.

(Technical Problems to be Solved by the Invention) The present invention provides a method for melting iron-based scrap that can reduce manufacturing costs by continuously preheating iron-based scrap to a high temperature, and that does not require a heat-resistant loss dollar. and a dissolving device.

(Means for Solving Technical Problems) That is, the present invention allows high-temperature gas to flow from the upper part to the lower part of the shaft furnace, and continuously supplies iron-based scrap from the lower part of the shaft furnace to counter-flow the high-temperature gas. A method for melting iron scrap in which the preheated iron scrap in the upper part of a shaft furnace is charged into a melting furnace and melted after heat exchange, and a high temperature gas supply port is formed in the upper part of the shaft furnace. This iron-based scrap melting device has an outlet for exhaust gas or fuel chemical gas in the lower part, a continuous raw material supply mechanism in the lower part of the shaft furnace, and a melting furnace connected to the upper part of the shaft furnace. .

(Effect of the invention) According to this invention, since the iron-based scrap is preheated with high-temperature gas while moving from the bottom to the top, the iron-based scrap that has been preheated to a high temperature is located at the top. .

Therefore, this iron-based scrap is not subjected to the load of the iron-based scrap in the lower part of the shaft furnace, and as a result, the iron-based scrap can be preheated to a high temperature close to its softening temperature. Moreover, since iron-based scrap can be continuously supplied, the heating efficiency of iron-based scrap is good. Furthermore, the iron-based scrap that has been preheated to a high temperature is in the upper part, and the lower part is not heated so much that there is no need for refractory rosdol.

(Example) The present invention will be described below with reference to an example shown in FIG. The shaft furnace 11 has a high temperature gas supply port 12 formed in the upper part, an exhaust gas outlet 13 formed in the lower part, and a continuous iron scrap supply mechanism 14 arranged therein. The high temperature gas supply port 12 communicates with the upper part of the melting furnace 16 via the high temperature gas flow pipe 15. The melting furnace 16 receives preheated iron scrap from the top and blows oxygen gas, fuel such as pulverized coal, carrier gas, and lime from the bottom to melt the iron scrap. This melting furnace 16 generates high-temperature gas (approximately 1800° C.) whose main components are CO and GO2. A heat recovery boiler 17 is arranged around the outer periphery of the flow pipe 15 . A ferrous scrap extrusion cylinder 18 is attached to the upper part of the shaft furnace 11, and can extrude preheated ferrous scrap 19 (preheated to about 1400° C.) from the upper part of the shaft furnace toward the flow pipe 15. It looks like this. Further, an exhaust gas pipe 20 is attached to the exhaust gas outlet 13, and the exhaust gas pipe 20 includes an exhaust gas blower 21 (or exhaust pressure turbine), a pressure detector 22, and a gas component analyzer 23.
are installed on each. A plurality of blowout pipes 24 are attached to the flow pipe 15 and the center of the shaft furnace 11, and these pipes can supply fuel such as gas, oil, pulverized coal, air, oxygen, etc. to discharge exhaust gas. It may also be burned to allow the scrap to be preheated. Shaft furnace 11
The ferrous scrap continuous supply mechanism 14 provided at the bottom includes a ferrous scrap pushing up cylinder 25 at the bottom, a ferrous scrap support plate 26 that can be opened and closed above the cylinder 25, and a ferrous scrap support plate 26 that can be freely opened and closed. A steel scrap supply port 27 is provided on the side surface of the steel scrap supply port.

High-temperature gas generated from the melting furnace 16 passes through the flow pipe 15, flows down from the upper part of the shaft furnace to the lower part, and is discharged through the exhaust gas pipe 20. Iron-based scrap is supplied between the cylinder 25 and the support plate 26 from the supply port 27 . At this time,
The high-temperature scrap 19 is pushed out by the cylinder 18, the support plate 26 is opened, and at the same time the cylinder 25 is pushed up to push the ferrous scrap 19 to the upper part of the shaft furnace 11. This operation is performed intermittently at regular intervals, so that iron-based scrap is continuously supplied. The iron-based scrap 19 in the shaft furnace 11 gradually ascends to the upper part of the shaft furnace 11 while being preheated by exchanging heat with the high-temperature exhaust gas flowing from the upper part to the lower part.

The cylinder 18 pushes out preheated ferrous scrap 19 and supplies it into the melting furnace 16 through the y-flow pipe 15. This operation
This is performed intermittently in conjunction with the iron scrap lifting cylinder 25.

According to this configuration and method, since the iron-based scrap that has been preheated to about 1400°C is located at the top of the shaft furnace 11, there is no need to support the iron-based scrap in the shaft furnace with this iron-based scrap. Can be heated to high temperatures.

Furthermore, the sensible heat and latent heat of the high-temperature gas from the melting furnace 16 can be effectively used to preheat the iron-based scrap, thereby reducing the amount of fuel used and lowering costs. In this case,
It is also possible to blow oxygen, air, etc. from the blow-off pipe 24 to combust some or all of the combustible gases (Go, H2, CI Hn) in the gas, and to lower the final exhaust gas temperature to 200° C. or lower. Further, in order to prevent overheating of the iron-based scrap, a portion of the high-temperature gas may be taken out from the upper part of the shaft furnace and used for other purposes. A part of the extracted gas may be used as the gas to be supplied to the blowout pipe 24. Note that it is also possible to perform an operation in which the supply of oxygen and air from the blow-off pipe 24 is stopped and exhaust gas containing CO is taken out from the exhaust gas pipe 20. Furthermore, if the iron-based scrap cannot be sufficiently preheated with only the exhaust gas from the melting furnace, an operation in which fuel is blown from the blow-off pipe 24 is also possible.

Next, an example of the material 70- of the present invention will be shown.

The following example shows the case of molten steel melting, but hot metal can also be melted by adjusting the carbon concentration and silicon concentration.

(Scrap) Input amount: 1103 kg Preheating temperature: 1400°C (shaft furnace outlet) (Blowing air) Injection I: 157 Nm3 (Gas generated from the melting furnace) Gas temperature: 1750°C Oxidation degree: 0.55 Gas composition: C035 %, CO2 35%, 829%, 82
0 19%, N22% (gas injected into the melting furnace, etc.), Oxygen: 86Nm3, Coal near 2ka, Carrier gas:
5. 4Nm3 Lime charged into the melting furnace: 46k.

(Products in the melting furnace) Molten steel: +1 to 1000 (GO, 05%), kg of slagnia (exhaust gas after scrap preheating) Flow rate: 291 Nm3 Composition: C0236%, 82028%, N244% Temperature:
ioo℃

[Brief explanation of the drawing]

First lashing Explanatory diagram of a melting furnace showing one embodiment of the present invention, Second lashing
The figure is an explanatory diagram showing a conventional example. 11...Shaft furnace, 12...High temperature gas supply port, 1
3... Exhaust gas outlet, 14... Iron-based scrap continuous supply mechanism, 15... High-temperature gas flow pipe, 16... Melting furnace, 17... Heat recovery boiler, 18... Iron-based scrap Scrap extrusion cylinder, 19... Iron scrap, 2o exhaust gas pipe, 21... Blower, 22... Pressure detector, 2
3...Component analyzer, 24...Blowout pipe, 25...
Iron-based scrubbing cylinder, 26... support plate,
27... Iron scrap supply port

Claims (2)

[Claims] (1) High-temperature gas is made to flow from the top to the bottom of the shaft furnace, and iron scrap is continuously supplied from the bottom of the shaft furnace to exchange heat with the high-temperature gas in a counterflow.
A method of melting iron-based scrap in which the iron-based scrap in the upper part of a preheated shaft furnace is charged into a melting furnace and melted. (2) A high-temperature gas supply port is formed in the upper part of the shaft furnace, an outlet for exhaust gas or fuel chemical gas is formed in the lower part of the shaft furnace, and a raw material continuous supply mechanism is arranged in the lower part of the shaft furnace, and the shaft A device for melting iron scrap that has a melting furnace connected to the top of the furnace.