JPH09159377A - Method of preheating cold iron resource and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the pressure drop of high temperature exhaust gas by adjusting the percentage of the void of cold iron resource by classifying the cold iron resource into three groups with the size of it, charging the each size of the cold iron resource into the preheating chamber and preheating it. SOLUTION: In preheating a scrap of iron by the exhaust gas of 1,000 deg.C to 1,500 deg.C generated by the operation of a metallurgical furnace, the scrap is classified into three groups of large, medium and small sizes and the scrap of each size are charged into the preheating chamber 3 of a preheating device in turn through a scrap hopper 6 opening a sectioning gate 5. The medium size scrap S2, the large size scrap S1 and the small size scrap S3 are charged in sequence into the preheating chamber inside a preheating device and preheated. Therefore, the percentage of the void of the cold iron resource is adjusted, the pressure drop of exhaust gas is controlled and the deposition of the cold iron resource is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method and an apparatus for preheating a cold iron source such as an iron scrap with high-temperature exhaust gas generated in the operation of a metallurgical furnace such as a converter and an electric furnace.

[0002]

2. Description of the Related Art Preheating a cold iron source such as iron scrap with high-temperature exhaust gas has been generally performed in metallurgical furnaces such as converters and electric furnaces. As prior art documents, JP-A-4-309789, JP-A-7-198
270-198274. By the way, in the conventional method for preheating a cold iron source, since the cold iron source is put into a preheating furnace at a time and preheated, the porosity of the cold iron source cannot be adjusted, and the pressure loss of the high-temperature exhaust gas cannot be controlled. Also, small pieces of the cold iron source are welded, and shelves are suspended in the preheating furnace, which makes it difficult to insert the cold iron source into the metallurgical furnace. Furthermore, since the size of the cold iron source varies, the entire preheating temperature cannot be made uniform. Further, since the preheating temperature is not uniform, it is difficult to predict the melting time in the metallurgical furnace. In particular, since the cold iron source has a different bulk density depending on its size, the ventilation resistance of the exhaust gas changes significantly, sometimes exceeding the capacity of the exhaust fan that sucks the exhaust gas, and the phenomenon of exhaust gas blowing from the furnace opening of the metallurgical furnace occurs. However, this not only deteriorates the working environment in the factory, but also causes air pollution.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention is capable of adjusting the porosity of a cold iron source, controlling the pressure loss of a high-temperature exhaust gas, preventing the cold iron source from welding, and suspending a shelf in a preheating chamber. In addition, the cold iron source can be set to a uniform preheating temperature, and the melting time in the metallurgical furnace can be predicted. Particularly, the ventilation resistance of the exhaust gas can be stabilized, and the exhaust gas blowing from the metallurgical furnace opening can be prevented. An object of the present invention is to provide a method and an apparatus for preheating a cold iron source.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for preheating a cold iron source according to the present invention is a method of preheating a scrap iron or the like by using high-temperature exhaust gas generated in the operation of a metallurgical furnace such as a converter or an electric furnace. When preheating an iron source, classify the cold iron sources into at least three types according to their size, and charge the cold iron sources of each size individually into the preheating chamber in the preheating device to preheat. It is a feature. In this preheating method, it is preferable to preheat after changing the order of charging the classified cold iron source into the preheating chamber in the preheating device in accordance with the operating condition of the metallurgical furnace and the exhaust gas condition. Further, it is preferable that the amount of the classified cold iron source is adjusted according to its size, and then charged into a preheating chamber in a preheating device to perform preheating. Further, it is preferable to adjust the amount and type of the classified cold iron source in accordance with the operating condition of the metallurgical furnace and the exhaust gas condition, and then charge the source in a preheating chamber in the preheating device to perform preheating.

[0005] The apparatus for preheating a cold iron source according to the present invention for carrying out the method for preheating a cold iron source described above has at least three or more preheating chambers for preheating the classified cold iron sources in a vertical tower. Preferably, it is provided. In this cold iron source preheating apparatus, it is preferable that the preheating chamber is partitioned by a gate, a door, and the like, each of which can be opened and closed and through which exhaust gas can pass.

It is preferable to provide a duct with a damper through which exhaust gas from the metallurgical furnace can individually pass through the preheating chamber. Further, it is preferable that each of the preheating chambers is provided with a combustion air blowing device or a combustion air intake. Further, it is preferable that an exhaust gas bypass duct not passing through the preheating chamber is provided. Further, it is preferable that a cold iron source temperature measuring device and a gas temperature measuring device are provided in each preheating chamber.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for preheating a cold iron source according to the present invention will be described. First, a preheating device for a cold iron source will be described with reference to the drawings. Reference numeral 1 denotes a vertical tower made of a refractory heat insulating material, which is provided in communication with an upper end of an inclined exhaust gas hood 2 made of a refractory heat insulating material of a metallurgical furnace (not shown). ing.
In this vertical tower 1, there are provided at least three preheating chambers 3 for preheating the classified cold iron source, and in the present example, four preheating chambers 3 are continuously provided. As shown in FIG. 2, each of the preheating chambers 3 can be opened and closed by a rotation holding shaft 4b supported by an outer bearing 4a, and has a comb-shaped or lattice-shaped gate or an exhaust gas-permeable gate. It is partitioned by a door 4.
A scrap hopper 6 having a scrap cutting gate 5 is provided above the uppermost preheating chamber 3 as shown in FIG. An exhaust gas bypass duct 7 which does not pass through the preheating chamber 3 is provided in the tower 1 which is provided in four chambers and is perpendicular to the preheating chamber 3, and dampers 8, 9 are provided at upper and lower ends of the exhaust gas bypass duct 7. In the middle, two stages of dampers 9 are provided at the same level as the gate or door 4. A duct 11 with a damper 10 that can individually pass through each of the preheating chambers 3 other than the uppermost preheating chamber 3 is provided in a branch in the middle of the exhaust gas bypass duct 7. On the opposite side of the exhaust gas bypass duct 7, an unburned gas combustion air duct having an unburned gas combustion air intake port 12 communicating with each preheating chamber 3 other than the uppermost preheating chamber 3 and the lowermost preheating chamber 3. 13
The unburned gas combustion air intake 12 is provided with a damper 14, and the unburned gas combustion air duct 13 is provided.
An air pushing fan 15 for combustion of unburned gas is provided on the inlet side of the fan. An exhaust gas outlet duct 16 is provided on the side of the exhaust gas bypass duct 7 so as to be continuous with the side surface of the uppermost preheating chamber 3 and the upper end of the exhaust gas bypass duct 7. Each of the preheating chambers 3 is provided with an infrared radiation thermometer 17 and a gas temperature measuring device 18 as a cold iron source temperature measuring device as shown in FIG. That is, a window 19 is provided on one side wall of the preheating chamber 3,
A heat-resistant glass 20 is stretched over the window 19, and an infrared radiation thermometer 17 is provided outside the window 19. A cooling gas is blown into the window 19 to remove dust and cool the heat-resistant glass. A cooling gas nozzle 21 is provided.
Further, a through hole 22 is provided in the other side wall of the preheating chamber 3, and a thermocouple of the gas temperature measuring device 18 is inserted into the preheating chamber 3 from the through hole 22, and the entrance of the through hole 22 is closed.

Next, a method of preheating a cold iron source, that is, iron scrap, using the preheating apparatus for a cold iron source configured as described above will be described. About 1000 ° C. to 1500 ° C. generated in the operation of a metallurgical furnace (not shown). When pre-heating iron scrap with high-temperature exhaust gas, the iron scrap is classified into three types, large, medium, and small in advance, and the scrap of each size is opened from the scrap hopper 6 to the scrap discharge gate 5, and sequentially. It is individually charged into the preheating chamber 3 in the preheating device. In the case of this example, the first charging is performed using a medium-sized (□ 300 to □ 100 mm) iron scrap S as shown in FIG.
_2. Large-sized (□ 500- □ 300 mm) iron scrap S ₁ , and small-sized (□ 100- □ 30 mm) iron scrap S ₃ . By thus, when the dissolution is almost completed initial charge Nyutetsu scrap in metallurgical furnace, iron scrap S ₂ medium size then the preheating chamber 3 and charged try to metallurgical furnace optimum temperature of about 800 Preheated to about ° C. When the order of the loading of the first round of scrap iron for the preheating chamber 3 and an iron scrap S ₁ of large size,
If it is not sufficiently preheated at the time of charging into the metallurgical furnace, and if the small-sized iron scrap S ₃ is used, welding occurs and shelves are suspended, so the first charging of the iron scrap into the preheating chamber 3 As described above, the medium size, the large size, and the small size are preferable. As a result, the large-sized and small-sized iron scraps S ₁ and S ₃ after the medium-sized iron scrap S ₂ are also preheated to the optimum temperature of about 800 ° C. substantially uniformly.

After the first charging of the iron scrap into the preheating chamber 3 has been performed in the order of medium size, large size, and small size as described above, large, medium, and small sizes are set depending on the operating conditions of the metallurgical furnace and the exhaust gas conditions. The charging order of the iron scraps S ₁ , S ₂ and S ₃ is appropriately selected and changed. For example, when the remaining operation time of the metallurgical furnace decreases, the small-sized iron scrap S ₃
Is charged into the preheating chamber 3 to obtain a predetermined preheating temperature by a short preheating. Also, when the operation of the metallurgical furnace is at its peak, and when the temperature of the generated gas rises, iron scraps S ₁ , S ₂ , and S ₃ of large size, medium size, and small size are charged in this order, Large-sized iron scrap S ₁ is preheated and the next medium-sized iron scrap S
₂ further preheating iron scrap S ₃ of small size, to prevent medium size, the welding of steel scrap small size.

In addition, by adjusting the amount of the classified iron scrap according to its size, the thickness of the layer in the preheating chamber 3 can be adjusted, and an excessive increase in ventilation resistance can be prevented. It is possible to prevent the exhaust gas from blowing out of the metallurgical furnace opening. That is, for the small-sized iron scrap S ₃ having a large bulk density and a small porosity, the amount of charging into the preheating chamber 3 is adjusted so that the layer thickness becomes small. scrap iron S ₁ size, adjusts the charging amount to the preheating chamber 3 as the layer thickness becomes thicker.

In the operation of a metallurgical furnace, the operation time, the operation method, the exhaust gas conditions, and the like vary depending on the reaction conditions in the furnace. In order to cope with these fluctuations, changing the type and amount of iron scrap to be charged into the preheating chamber 3 is a condition for performing efficient preheating. For example, when the operation time of the metallurgical furnace is shortened or the exhaust gas temperature is decreasing, a small amount of small-sized iron scrap S ₃ is charged into the preheating chamber 3 and the operation in which the generation of high-temperature gas continues for a long time Then large-sized iron scrap S
By taking measures such as charging only ₁ into the preheating chamber 3, the heat energy of the exhaust gas can be efficiently used for preheating the iron scrap. Also, if the temperature of the iron scrap does not rise to the predetermined temperature in one operation of the metallurgical furnace,
It is also possible to adopt a method in which the cutting of the iron scrap from the preheating furnace is stopped, and the scrap is heated again by the next operation and then cut.

However, in the preheating apparatus for a cold iron source according to the embodiment, since the preheating chamber 3 is at least equal to the classification number of the iron scrap as described above, the preheating can be performed for each iron scrap of the same size. Therefore, the porosity can be adjusted, the pressure loss of the high-temperature exhaust gas can be controlled, the welding of the iron scrap can be prevented, the hanging of the shelf in the preheating chamber 3 can be eliminated, and the iron scrap can be easily charged into the metallurgical furnace. Further, it is possible to make the iron scrap to have a uniform preheating temperature and to predict the melting time in the metallurgical furnace.

The preheating chamber 3 is divided by a comb-shaped or lattice-shaped gate or door 4 that can be opened and closed and that allows exhaust gas to pass therethrough. After being moved to the preheating chamber 3 and preheated to a predetermined temperature in the final preheating chamber 3, it is charged into the metallurgical furnace. In addition, since the duct 7 through which the exhaust gas can bypass each of the preheating chambers 3 is provided in the preheating apparatus of the embodiment, the temperature of the iron scrap in the preheating chamber 3 can be prevented from rising more than necessary, and the welding is performed. And abnormal rise of ventilation resistance can be prevented. Moreover, in the event of an unexpected accident such as equipment failure, welding in the preheating chamber 3 or blockage by dust, the exhaust gas is supplied to the preheating chamber 3.
Since it can be bypassed, sufficient safety can be secured even in an emergency.

[0014] Incidentally, the high temperature exhaust gas generated in the operation of a metallurgical furnace, CO, contains unburnt gases such as H _2, C _m H _n. In the preheating of iron scrap, these unburned gases are also burned as a heat source.However, applying this combustion heat to all iron scrap depends on the size of the iron scrap, such as excessive rise in preheating temperature and welding. Phenomena may occur. However, in the preheating apparatus according to the embodiment of the present invention, the unburned gas combustion air duct 13 having the unburned gas combustion air intake port 12 is provided below each preheating chamber 3, so that the unburned gas Preheating chamber 3 containing iron scraps that need to be preheated by utilizing the combustion heat of
On the lower side, the unburned gas can be selectively combusted by opening the damper 14, and the combination with the exhaust gas bypass duct 7 makes it possible to selectively open and close the dampers 9, 10. Combustion is possible in the chamber and in all preheating chambers 3 and in the preheating chamber 3 at an intermediate position.

In the preheating apparatus of the embodiment, each preheating chamber 3
Is provided with an infrared radiation thermometer 17 and a gas temperature measuring device 18 as a cold iron source temperature measuring device, so that the temperature of the iron scrap and the exhaust gas temperature in each preheating chamber 3 are measured. The target preheating in the chamber can be accurately performed, and the flow of exhaust gas and the control of combustion can be accurately performed.

[0016]

As can be seen from the above description, the method for preheating a cold iron source according to the present invention classifies the cold iron sources and individually preheats the respective sizes of the cold iron sources with exhaust gas from a metallurgical furnace. The porosity of the source can be adjusted, the pressure loss of the exhaust gas can be controlled, the welding of the cold iron source can be prevented, and the temperature can be preheated to a uniform temperature for each size, and the melting time in the metallurgical furnace can be predicted. In particular, by adjusting the amount of each type of cold iron source for each size, the thickness of the layer through which the exhaust gas passes is adjusted, and the ventilation resistance is stabilized, so the phenomenon of exhaust gas emission from the metallurgical furnace opening is prevented. Is done.

According to the apparatus for preheating a cold iron source of the present invention,
Not only can the preheating method exhibiting the above effects be implemented accurately, but also the flow route of exhaust gas can be changed as appropriate to adjust the temperature of iron scrap, and emergency situations such as equipment failures and unforeseen accidents such as welding and clogging by dust can occur. At times, safety can be sufficiently ensured. In addition, since unburned gas in the exhaust gas can be burned and preheated, the thermal energy of the exhaust gas can be efficiently used.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a preheating apparatus for carrying out a method for preheating a cold iron source according to the present invention.

FIG. 2 is a cross-sectional plan view taken along line AA of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vertical tower 2 Exhaust gas hood 3 Preheating chamber 4 Gate or door 4a Bearing 4b Rotation holding shaft 5 Scrap cut-out gate 6 Scrap hopper 7 Exhaust gas bypass duct 8, 9, 10 Damper 11 Duct 12 Unburned gas combustion air intake 13 Not yet Combustion gas combustion air duct 14 Damper 15 Unburned gas combustion air push-in fan 16 Exhaust gas outlet duct 17 Cold iron source temperature measurement device (infrared radiation thermometer) 18 Gas temperature measurement device S ₁ Large iron scrap S ₂ Medium Iron scrap of size S ₃ Iron scrap of small size

Front page continuation (72) Inventor Yoshinori Okuyama 2-11-1, Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Design Office (72) Inventor Nobuyuki Fujikura 2-11-1, Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industry Co., Ltd. Tokyo Design Office

Claims (10)

[Claims] When preheating a cold iron source by high-temperature exhaust gas generated in the operation of a metallurgical furnace, the cold iron source is classified into at least three types according to its size, and the cold iron sources of each size are individually classified. A method for preheating a cold iron source, comprising charging a preheating chamber in a preheating device and preheating. 2. The method for preheating a cold iron source according to claim 1, wherein the order of charging the classified cold iron source into a preheating chamber in a preheating device is adjusted in accordance with an operation state of a metallurgical furnace and an exhaust gas state. A preheating method for a cold iron source, which comprises preheating after being changed. 3. The method for preheating a cold iron source according to claim 1 or 2, wherein the amount of the classified cold iron source is adjusted according to its size, and then charged into a preheating chamber in a preheating device. A method for preheating a cold iron source. 4. The method for preheating a cold iron source according to claim 1, wherein the amount and type of the classified cold iron source are adjusted in accordance with the operating condition of the metallurgical furnace and the exhaust gas condition, A preheating method for a cold iron source, wherein the preheating is performed by charging the preheating chamber by preheating it. 5. A preheating apparatus for a cold iron source, wherein at least three or more preheating chambers for preheating the classified cold iron source are provided in a vertical tower. 6. The cold iron source preheating apparatus according to claim 5, wherein the preheating chamber is partitioned by a gate, a door, and the like, which can be opened and closed and through which exhaust gas can pass. Source preheating device. 7. The preheating apparatus for a cold iron source according to claim 5, further comprising a duct with a damper through which exhaust gas from the metallurgical furnace can individually pass through each preheating chamber. Preheating device for cold iron source. 8. The preheating apparatus for a cold iron source according to claim 5, wherein a combustion air blowing device or a combustion air intake is provided in each preheating chamber. Characteristic preheating device for cold iron source. 9. A preheating apparatus for a cold iron source according to claim 5, wherein an exhaust gas bypass duct which does not pass through a preheating chamber is provided. . 10. The cold iron source preheating apparatus according to claim 5, wherein a cold iron source temperature measuring apparatus and a gas temperature measuring apparatus are provided in each of the preheating chambers. Preheating device for cold iron source.