JP3106042B2 - How to preheat scrap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preheating scrap. More specifically, the present invention relates to a method for preheating scrap in a case where molten steel is obtained by putting steel scrap into molten iron.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to increase the amount of steel scrap (hereinafter, simply referred to as scrap). Therefore, it is required to put this scrap into hot metal before being transferred to a converter in a steelmaking process and to recycle the scrap. ing. So, conventionally,
For example, as shown in FIG. 8, a scrap 102 is spread over a hot metal pot 101 (which is also referred to as a red pot from a state in which the hot metal is red-heated) heated to near the temperature of the hot metal in advance, and the scrap 102 is preheated by the radiant heat of the hot metal pot 101. Then, hot metal is poured. Alternatively, a cold scrap 102 is transferred from a scrap chute 104 to a converter 103.
After pouring the hot metal, the hot metal is poured. Then, the molten iron and the scrap 102 are transferred to the converter 103 and then oxygen is blown. In the converter 103, oxygen is blown into the high-temperature pig iron to cause an exothermic reaction with carbon in the pig iron and to remove carbon to produce steel.
At this time, since the scrap contains no carbon content than the pig iron, it is necessary to replenish this amount separately and compensate for the heat for melting the injected scrap. Therefore, increasing the percentage of scrap will increase carbon input,
It is necessary to add another heating agent to compensate for the heat.

[0003]

However, the carbon source added for thermal compensation is expensive because it contains as little impurities as possible. For this reason, it is desired that the amount of carbon added be as small as possible. Also, if the amount of scrap increases without adding enough carbon for heat compensation, the heat inside the converter is taken away and melted, so the amount of heat taken away by the scrap is greater than the amount of generated heat and the function as a converter is increased. There is a possibility that it will not work. For this reason, the amount of scrap input is naturally limited.

[0004] It is an object of the present invention to provide a method for preheating scrap which can reduce carbon for thermal compensation and can shorten refining time.

[0005]

In order to achieve the above object, a method for preheating scrap according to the first aspect of the present invention provides a method for preheating a scrap.
The supply of air and the emission of combustion gas are alternately performed through the heat storage.
High temperature combustion air close to the temperature of the combustion gas
Storage burner system that burns different burners alternately in a short time
A lid having at least one system
Use the lid to open the bucket chute opening
It is substantive sealed between closed by said bucket chute
To form a closed space, and within the closed space, the pair of buses.
Heat storage from the other burner while burning one of the burners
The alternating combustion that exhausts the combustion gas through the body for a short time
Periodically to form an atmosphere with a uniform temperature distribution,
The scrap inside the ket chute is preheated .

Further, a method for preheating scrap according to claim 2 is provided.
The law uses heat storage to supply combustion air and discharge combustion gases.
High temperature combustion air close to the temperature of the combustion gas
Storage in which a pair of burners alternately burn in a short time
At least one thermal burner system
Scrap container for preparing a lid and storing scraps with the lid
Close the mouth of the container to substantially close the scrap container.
Form a closed space, and within the enclosed space,
Forward from the other burner while burning one of the pair of burners
The alternate combustion in which the combustion gas is exhausted through the heat storage body is shortened.
Perform at regular intervals of time to form an atmosphere with a uniform temperature distribution
Pre-heat the scrap in the scrap container
ing.

A method for preheating scrap according to claim 3 is provided.
The law uses heat storage to supply combustion air and discharge combustion gases.
High temperature combustion air close to the temperature of the combustion gas
Storage in which a pair of burners alternately burn in a short time
At least one thermal burner system
Prepare a lid, spread the scraps in advance with the lid
Close the ladle before heating and close the ladle substantially with the ladle.
Form a closed space, and within the enclosed space,
Forward from the other burner while burning one of the pair of burners
The alternate combustion in which the combustion gas is exhausted through the heat storage body is shortened.
Perform at regular intervals of time to form an atmosphere with a uniform temperature distribution
Pre-heating the scrap simultaneously with heating the ladle
I'm trying.

[0008] Here, the lid is located on the upper surface and side of the closed space.
Form an L-shape that closes one of the surfaces, and
Being arranged on the upper surface and the side surface, respectively.
The lid has a pair of burners projecting into the closed space.
Providing a partition wall that partially partitions the enclosed space between,
When the pair of burners are fired alternately, the partition wall is bypassed.
Turn the burner so that it is exhausted from the regenerator
Is preferable. Furthermore, a heat storage type burner system
The scrubber according to claim 5 is not only used in the case of mounting on the lid.
The supply of combustion air and the combustion gas
Alternately through the regenerator to reduce the temperature of the combustion gas.
Nearly high-temperature combustion air enables a pair of burners in a short time
At least one regenerative burner system with alternating combustion
Scrap container provided opposite to the system and on both side walls
Prepare a container and store the scrap in the scrap container
And cover the scrap container with a lid,
Form a substantially sealed space between the top container and the lid.
One of the pair of burners in the enclosed space.
While burning the fuel from the other burner via the regenerator
The alternate combustion for exhausting the combustion gas is performed in a short cycle.
To form an atmosphere with a uniform temperature distribution and
The scrap in the vessel may be preheated.

[0009]

Therefore, the scrap is accommodated in a closed space formed by closing any one of the bucket chute and the scrap container or the other container for storing the ladle or the scrap before the heating with the lid, and the lid or the bucket chute. The scrap is heated by the radiant heat of the high-temperature flame obtained by the combustion of the regenerative burner system mounted on the scrap container and the flow of the combustion gas. When the combustion gas that has exchanged heat with the scrap is exhausted through the regenerator on the burner side during which combustion is stopped, the sensible heat is recovered by the regenerator. Then, the heat recovered in the heat storage body is used for preheating the combustion air with extremely high heat exchange efficiency by direct heat exchange, and is returned to the furnace again. Since the temperature of the combustion air at this time can be set to a high temperature close to the temperature of the exhaust gas to be exhausted, heat from combustion of the fuel is further added to the temperature to rapidly raise the furnace temperature and obtain a high-temperature flame. . Further, in the case of alternately burning in a short time, the flame position changes frequently, so that the temperature distribution in the closed space is made more uniform, and the entire scrap is uniformly heated without overheating a part of the scrap.

Here, in the case of the invention of claim 6, since the sealed space is partitioned by a partition wall protruding into the sealed space except for the portion where the scraps are stacked, the combustion gas is short-passed between the paired burners. Without being caused, the air is reliably bypassed over the partition wall, passes between the scraps, and is exhausted from the heat storage body of the burner on the opposite side.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings. In the present embodiment, the structure itself, such as a ladle or a bucket chute, which constitutes the closed space is not particularly important, and a detailed description thereof will be omitted.

FIG. 1 is a conceptual diagram showing an example of a method for preheating scrap according to the present invention. This scrap preheating method is performed by closing the opening of the bucket chute 1 with a lid 3 equipped with a regenerative burner system 4 and alternately burning. A pair of burners 5 and 6 constituting the heat storage type burner system 4 close an opening formed in the upper surface and the front surface of the bucket chute 1 to form a substantially sealed space 2 with the bucket chute 1. It is equipped on the L-shaped lid 3. Specifically, one burner 5 constituting one regenerative burner system 4 is attached to the upper surface of the lid 3, and the other burner 6 is attached to the front of the lid 3.

The lid 3 for closing the bucket chute 1 is provided with a device as necessary to make the movement (agitating property) of the combustion gas 17 in the closed space 2 more preferable. For example, as shown in FIG. 2, a partition wall 18 that protrudes into the closed space 2 and partially partitions between a pair of burners 5 and 6 is provided at the center of the lid 3. The partition wall 18 completely partitions the space above the portion where the scrap W is stacked, and prevents the combustion gas 17 from being short-passed between the pair of burners 5 and 6 disposed across the partition wall 18. I have. In this case, the combustion gas 17 bypasses the partition wall 18 and is exhausted from the burner on the opposite side of the partition wall 18, so that it flows so as to pass between the scraps W. Note that the partition wall 18 is integrally formed of the same refractory material as the lid 3.

The structure of the closed space 2 between the lid 3 and the lid 3 is not particularly limited to the above-described bucket chute 1, and a scrap container 21 as shown in FIG. 3 may be employed. In this case, at least a pair of burners 5 and 6 are arranged near the bottom of both side walls of the scrap container 21 so as to face each other, and the combustion gas 17 is provided between them. At this time, the lid 3 is not equipped with a regenerative burner system.

Further, as shown in FIG. 4, a closed space 2 may be formed by covering a scrap container 31 having only one surface opened with a lid 3 equipped with a heat storage type burner system 4. In this case, the lid 3 has a pair of burners 5,
A partition wall 32 protruding into the closed space 2 is provided between the fuel cells 6, and the combustion gas 17 is provided so as to flow around the partition wall 32. Therefore, the combustion gas 17 passes through the scrap W stored in the scrap container 31 without fail.

The heat storage type burner system 4 mounted on the above-mentioned lid 3 or the scrap container 31 is not particularly limited in its structure and combustion system. For example, as shown in FIG. The burned duct 14 is connected to the burner body 13 and two heat storage bodies 7 and the burners 5 and 6 are combined and alternately burned, and the exhaust gas is discharged through the stopped burner and the heat storage body that are not burning. What is provided in this embodiment is used in this embodiment. A combustion air supply system 8 for supplying combustion air to the regenerators 7 of the two burners 5 and 6 and a combustion gas exhaust system 9 for discharging combustion gas are selectively provided by a four-way valve 10. So that one burner 5 (or 6) is supplied with combustion air through the heat storage 7 while the other burner 6 (or 5) is configured to discharge combustion gas through the heat storage 7. Is provided. The combustion air is supplied by, for example, a pushing fan 16 or the like, and the combustion exhaust gas is sucked from an enclosed space 2 formed by a lid 3 and a bucket chute 1 by an exhaust means such as an induction fan (not shown) and discharged into the atmosphere. Is done. Further, the fuel supply system 11 is selectively and alternately connected to one of the burners 5, 6 via a three-way valve 12, for example, to supply fuel. The fuel nozzle 15 is, for example, buried in a burner throat portion of the burner body 13 and has only an injection port opened on the inner peripheral surface of the burner throat, and is provided so as not to be exposed to the combustion gas when passing through the inside. .

The heat storage bodies 7 have a large number of honeycomb-shaped cell holes formed of a material having a large heat capacity and a high durability, for example, ceramics such as mullite and cordierite, while having a relatively low pressure loss. The use of a cylinder is preferred. In this case, even if the gas drops below the acid dew point when recovering heat from the combustion gas, the sulfur content in the fuel and its chemically changed substances are trapped in the ceramics, and the low-temperature exhaust duct and other parts are corroded at low temperatures. I will not let you. Of course, the present invention is not particularly limited to this, and a heat storage body made of another material or structure such as a ceramic ball or a nugget may be used.

A case where the scrap W is preheated using the closed space 2 provided with the heat storage type burner system 4 configured as described above will be described with reference to an example using the scrap chute shown in FIG.

First, the upper opening and the front opening of the bucket chute 1 are closed by the lid 3 having the heat storage type burner system 4. Then, a closed space 2 is formed by the bucket chute 1 and the lid 3.
To form Combustion gas 1 flows from the burner throat of one burner constituting the heat storage type burner system 4, for example, the burner 5 which is not burning at the same time as burning the burner 5.
7 is extracted and passed through the regenerator 7 so that the combustion gas exhaust system 9
Exhaust from That is, the other burner 6 is connected to the combustion gas exhaust system 9 by switching the four-way valve 10 and the fuel supply is closed by the three-way valve 12, so that combustion is not performed and the burner 6 is used as a discharge path of the combustion gas. Bucket chute 1
Is heated by the flame and the radiant heat of the combustion gas 17. Here, the combustion air supplied to the burner 5 is preheated by direct contact with the regenerator 7 and then supplied into the burner body 13 and has a high temperature (about 1000 ° C.) close to the exhaust gas temperature. Therefore, the fuel nozzle 1
When mixed with the fuel injected from No. 5, a combustion gas having a high temperature sufficient to stably burn even with a small amount of fuel and to preheat the scrap W is obtained. If necessary, a high-temperature flame higher than that of an oxygen-enriched burner can be easily obtained by injecting a sufficient amount of fuel. In addition, the temperature of the combustion air changes instantaneously as the amount of combustion increases or decreases, so that the responsiveness of adjusting the temperature of the combustion gas is good. Therefore, the ambient temperature of the closed space 2 can be rapidly raised to a temperature suitable for preheating the scrap W. Switching between combustion and exhaust is performed, for example, at intervals of 10 seconds to 2 minutes, preferably within about 1 minute, and most preferably 1 minute.
It is performed at extremely short intervals of about 0 to 40 seconds. Further, the switching is performed when the combustion gas discharged through the heat storage unit 7 reaches a predetermined temperature, for example, about 200 ° C. In this case, since the flame position changes frequently, the atmosphere temperature in the closed space 2 can be made more uniform, and the uneven heating is reduced, so that the entire scrap is uniformly heated without overheating some of the scrap W.

The above embodiment is one preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG. 6, a scrap W is spread in advance in a ladle 41 before heating, and in that state,
The opening of the ladle is closed space 2 by closing the mouth 1 with the lid 3. Then, by injecting the combustion gas 17 into the ladle 41,
At the same time as the ladle 41 is heated, the radiant heat radiated from the refractory lining of the ladle 41 by the scrap W is used for preheating the scrap W, and the lining refractory is heated by the radiant heat radiated from the scrap W. It is also possible to Here, the lid 3 is provided with a partition wall 42, and is provided so as to bypass the partition wall 42 and exhaust the combustion gas 17. In this case, the heating efficiency is improved.

The regenerative burner system 4 is not particularly limited to the alternating combustion type shown in FIG. 5, but burns a burner determined by relatively switching the flow of exhaust gas and combustion air to the regenerator. It may be one that is made to continue. For example, as shown in FIG. 7, the combustion gas and the combustion air for the heat storage 52 are controlled by rotating the heat storage 52 between the exhaust system 53 and the combustion air supply system 54 while keeping the burner 51 burning constant. May be switched relatively. That is, in the case of the regenerative burner system 4, one burner 51, one exhaust port 55, a combustion air supply system (duct) 54 for supplying combustion air to the burner 51, and an exhaust port 55
An exhaust system (duct) 53 which is connected to the exhaust system and extracts exhaust gas therein and exhausts the exhaust gas into the atmosphere or the like;
Rotary heat storage element 52 disposed over the fuel cell 4 and the exhaust system 53
It is composed of Here, the exhaust port 55 is, for example, the lid 3 or the bucket chute or the scrap container 2.
1 and the like, and is constituted by a burner mounting hole drilled in a wall surface of the wall 1 or a refractory tube attached to the hole.
The rotary heat storage element 52 has a disk shape, and is provided so as to rotate in a casing 58 made of a heat-resistant metal or the like partitioned into two chambers 57a and 57b around a rotary shaft 56 disposed at the center thereof. ing. Therefore, the heat storage body 52 is heated to almost the same temperature by the combustion gas discharged in the chamber 57b connected to the exhaust system 53, and then moves to the chamber 57a side connected to the combustion air supply system 54 to be used for combustion. It comes into contact with air and heats the combustion air to a temperature slightly lower than the flue gas.

[0022]

As is apparent from the above description , according to the scrap preheating method of the present invention, the temperature of the hot metal is brought close to the temperature of the hot metal in advance.
Prepare the hot metal pot heated in
At least to transport scrap to the converter
There are existing bucket chutes and scrap containers used
Closed space suitable for heating scrap using ladle
And preheating of the scrap can be performed. Moreover,
After being used to heat the wrap, the combustion gases pass through the regenerator.
When exhausted, the sensible heat is collected by the heat storage,
It is used again for preheating the combustion air and thrown into the enclosed space.
As a result, a high-temperature, high-velocity flame is obtained,
Well, the scrap is heated up to the specified preheating temperature in a short time.
obtain. In addition, the flame position is set to alternately burn in a short time.
Frequent changes and more uniform temperature distribution in enclosed space
May cause some scrap to be overheated.
The entire scrap can be heated uniformly.

Further, in the case of the invention of claim 4, a pair of bars are provided.
The flow of combustion gas between the nozzles crosses the enclosed space at the longest.
The entire scrap is heated to form a path
Preheating variation is reduced.

Further , in the case of the invention of claim 6, in the closed space.
Enclosed space is piled up by scrap
Bars that are paired because they are separated except for the raised part
The combustion gas can be reliably
Detour over the cut wall, pass between scraps and on the other side
It is exhausted from the heat storage body of the burner, so it is stored in a closed space
Ensures that the combustion gas passes between the scraps
Can be heated.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a method for preheating scrap according to the present invention using a bucket chute.

FIG. 2 is a conceptual view showing another embodiment of the scrap preheating method of the present invention using a bucket chute.

FIG. 3 is a conceptual diagram showing still another embodiment of the scrap preheating method of the present invention using a scrap container.

FIG. 4 is a conceptual diagram showing still another embodiment of the scrap preheating method of the present invention using a scrap container.

FIG. 5 is a principle view showing one embodiment of a heat storage type burner system applied to the present invention.

FIG. 6 is a conceptual diagram showing still another embodiment of the scrap preheating method of the present invention using a ladle.

FIG. 7 is a principle view showing another embodiment of the heat storage type burner system applied to the present invention.

FIG. 8 is a conceptual diagram showing an example of a conventional scrap preheating method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bucket chute 2 Enclosed space 3 Lid 4 Thermal storage burner system 5, 6 Burner 7 Thermal storage 18, 32 Partition wall 21 Scrap container equipped with thermal storage burner system 31 Scrap container 41 Ladle

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Sato 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hiroshi Kurihara 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (72) Inventor Ryoichi Tanaka 2-1-153 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa Japan In-house Furniture Industry Co., Ltd. (72) Inventor Mamoru Matsuo 2-1-153 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Inside Furnace Industry Co., Ltd. (72) Inventor Makoto Miyata 2-1-153 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Japan Furnace Industry Co., Ltd. (56) References JP-A-62-27530 (JP, A) JP-A Sho 61-15080 (JP, A) Japanese Utility Model Application 3-121309 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F27D 13/00 C21C 5/28

Claims (6)

(57) [Claims] 1. The supply of combustion air and the discharge of combustion gas
High temperature close to the temperature of the combustion gas is performed alternately through the heat storage
Combustion air alternately burns a pair of burners in a short time
At least one regenerative burner system
Prepare a lid on top, and use the lid to store the scraps
Cover the opening of the bucket chute and
Form a substantially enclosed space between the sealed
While burning one of the pair of burners in the
The combustion gas from the burner through the heat storage
The alternate combustion is performed in a short period of time to obtain a uniform temperature distribution.
Scrap in the bucket chute to form an atmosphere
A method of preheating scrap. 2. The supply of combustion air and the discharge of combustion gas
High temperature close to the temperature of the combustion gas is performed alternately through the heat storage
Combustion air alternately burns a pair of burners in a short time
At least one regenerative burner system
Prepare a lid provided on top, and use the lid to
Cover the mouth of the wrap container and carry out the
Form a qualitatively closed space, and within the closed space
While burning one of the pair of burners, the other bar
The combustion gas is exhausted from the heat storage body through the heat storage
Combustion is performed in a short cycle to create an atmosphere with a uniform temperature distribution.
Forming and preheating scrap in said scrap container
A method for preheating scrap. 3. The supply of combustion air and the discharge of combustion gas are performed.
High temperature close to the temperature of the combustion gas is performed alternately through the heat storage
Combustion air alternately burns a pair of burners in a short time
At least one regenerative burner system
Prepare the upper lid and lay the scrap in advance with the lid
Close the ladle before heating and tighten the ladle with the ladle.
Form a qualitatively closed space, and within the closed space
While burning one of the pair of burners, the other bar
The combustion gas is exhausted from the heat storage body through the heat storage
Combustion is performed in a short cycle to create an atmosphere with a uniform temperature distribution.
Forming and heating the ladle and preheating the scrap simultaneously
Characterized by performing How to preheat scrap. 4. The lid according to claim 1, wherein said lid is formed on one of an upper surface and a side surface of said closed space.
Form an L-shape for closing the pair of burners, and
Characterized in that they are arranged on the side surfaces, respectively.
The method for preheating scrap according to claim 1. 5. The supply of combustion air and the discharge of combustion gas
High temperature close to the temperature of the combustion gas is performed alternately through the heat storage
Combustion air alternately burns a pair of burners in a short time
At least one regenerative burner system
Preparing scrap containers provided opposite to both upper side walls
And the scrap is stored in the scrap container.
Cover the mouth of the scrap container with a lid, and
Forming a substantially sealed space between the
Burning one of the pair of burners in an enclosed space
Combustion gas from the other burner through the heat storage
The alternating combustion to be exhausted is performed in a short cycle to obtain a uniform
An atmosphere having a temperature distribution is formed to form a gas in the scrap container.
Scrap preheating characterized by preheating the scrap
Method. 6. The lid protrudes into the closed space,
Partition wall that partially partitions the closed space between a pair of burners
When burning the pair of burners alternately.
Bypassing the partition wall and discharging from the heat storage body of the burner during which combustion is stopped
6. The method according to claim 1, wherein
The scrap preheating method according to any one of the above.