JP2001116225A - Waste plastic combustion burner for arc furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste plastic combustion burner for an arc furnace which can enhance the combustion rate of waste plastic in a burner and can utilize the heat obtained by the combustion to the fusion of scrap effectively, while using waste plastic of economical size of about several mm to ten-odd mm. SOLUTION: This is a burner which is equipped with a passage 10 for carrying waste plastic by gas and blows it into an arc furnace, at the center, a fuel passage 11 around it, an oxygen passage 12, a cooling water passage 13, and a combustion tube 14 between the tip of the burner and a furnace wall, and is provided with a conical flow straightening member 15 in the jet port of the passage 10 of the waste plastic. Moreover, in place of the flow straightening member 15, the oxygen passage 12 is arranged around the fuel passage 11, and the jet port of the oxygen passage 12 is inclined in the direction of center axis of the burner, or a pilot burner 17 may be provided in front of the jetting port of the passage 10 of the waste plastic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the dissolution of metallic materials,
The present invention relates to a waste plastic combustion burner provided on a furnace wall and a furnace lid of an arc furnace used for refining molten metal.

[0002]

2. Description of the Related Art In recent years, waste plastic discarded as industrial waste or general waste has been increasing. On the other hand, there is a growing demand for carbon dioxide reduction as a major theme of environmental protection on a global scale.In this case, waste plastic is recycled as a material or heat source instead of being treated by conventional incineration or landfill. Is increasing. In particular, under the current situation where waste plastics are mixed with various types of plastics, thermal recycling has attracted attention in terms of processing costs, and research and development of thermal recycling of waste plastics has been carried out in many industrial furnaces. Various burner structures for efficiently burning waste plastic have been proposed.

For example, in Japanese Patent Application Laid-Open No. Hei 7-71728, a nozzle for spraying liquid fuel is arranged around a nozzle for blowing powder of waste plastic having a particle diameter of 1 mm or less, so that the powder of waste plastic can be reliably removed. A burner structure for ignition and stable combustion has been proposed. Also, Japanese Patent Application Laid-Open
Japanese Patent No. 185115 proposes a structure of a burner for an industrial waste incinerator for burning a metal wire coated tip of about 1 to 2 mm. In the burner disclosed in this publication, a nozzle that ejects a metal wire-coated chip linearly from the rear end of the burner into the incinerator and an ignition burner provided around the nozzle are provided so that the burner body made of a refractory material is not overheated. It is characterized by burning the metal wire coated tip.

[0004]

The burners proposed in the above publications are intended to blow powdery waste plastic of about 1 to 2 mm, but generally, when the waste plastic is pulverized to about 1 to 2 mm. Processing costs are required, and the bulk specific gravity is reduced, and transportation costs are required. Therefore, there is a problem that the merit of using waste plastic as a heat source is reduced. In order to enjoy a sufficient cost merit by thermal recycling of waste plastic, it is desirable that the size of waste plastic used for blowing is about several mm to several tens of mm.

[0005] The above-mentioned burner is assumed to be used in a furnace such as a waste incinerator having a space inside the furnace in front of the burner. For this reason, the burner proposed in JP-A-7-71728 does not have a combustion chamber in the burner itself, and the burner disclosed in JP-A-10-185115 does not discharge waste air blown from an ejection nozzle as described in the description. It is not necessary for the plastic to burn sufficiently in the burner, and it has been proposed to protect the refractory of the burner body by employing a structure in which a certain percentage of waste plastic burns in the furnace.

As described above, various structures have been proposed for waste plastic combustion burners. However, most of them have been proposed for incinerators, and most have been proposed for arc furnaces. Absent.

[0007] In an arc furnace, scrap as a raw material is charged into the furnace so as to fill the furnace, the scrap is melted mainly by the energy of the arc generated in the center of the furnace, and the scrap near the furnace wall far from the arc generating portion is melted. Oil and gaseous fuel combustion burners have been used to assist the combustion. Therefore, it is assumed that scrap is present on the front surface of the burner, and particularly in the initial stage of melting of the scrap, there is almost no space on the front surface of the burner. Under such a condition, when a waste plastic combustion burner proposed in the above-mentioned publication is used as a substitute for a burner of oil or gaseous fuel, the flow rate of waste plastic and gas such as air for transporting the waste plastic are particularly increased. When the flow rate increases, waste plastic and carrier gas ejected from the central part of the burner blow off without contacting the flame formed by the combustion of fuel, and waste plastic that has not been burned or has just been heated is located near the furnace wall. The heat of combustion of the scrap is generated because it bounces off the scrap and adheres to the water-cooled furnace wall and burns, or is collected from the furnace through a small space between the scrap near the furnace wall and the water-cooled furnace wall. The problem of not sufficiently contributing to dissolution occurs. Also, needless to say, when blowing waste plastic having an economic size of about several mm to several tens of mm, the combustion speed is slow, so that the use efficiency of the above-described combustion heat is further reduced. Become.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and uses waste plastic having an economical size of about several mm to several tens of mm while using waste plastic in a burner. It is intended to provide a waste plastic combustion burner for an arc furnace, which can improve the combustion rate of the waste and effectively use the heat obtained by the combustion for melting the scrap.

[0009]

That is, the present invention is to solve the above problems, and the gist thereof is as follows. (1) A flow path of the waste plastic which gas-conveys the waste plastic into the center and blows it into the arc furnace, a fuel flow path which blows the fuel into the arc furnace at the outer periphery thereof, an oxygen flow path which blows oxygen into the arc furnace, In a waste plastic combustion burner provided with a cooling water flow path for cooling a combustion burner and a combustion cylinder between a burner tip and a furnace wall, a waste plastic flow diverging into the combustion cylinder is supplied to a discharge port of the waste plastic flow path. A waste plastic combustion burner for an arc furnace, comprising a cone-shaped flow straightening member to be formed. (2) A flow path of the waste plastic that gas-transports the waste plastic into the arc furnace and blows it into the arc furnace in the center, a fuel flow path that blows the fuel into the arc furnace at the outer periphery, a cooling water flow path that cools the combustion burner, and a burner. In a waste plastic combustion burner provided with a combustion cylinder between the furnace wall from the tip, an oxygen flow path for blowing oxygen into the arc furnace is arranged on the outer periphery of the fuel flow path,
A waste plastic combustion burner for an arc furnace, wherein a jet port of the oxygen flow path is inclined in a direction of a burner central axis. (3) A flow path of the waste plastic which gas-conveys the waste plastic to the center and blows it into the arc furnace, a fuel flow path which blows the fuel into the arc furnace on the outer periphery thereof, an oxygen flow path which blows oxygen into the arc furnace, In a waste plastic combustion burner provided with a cooling water flow path for cooling the combustion burner and a combustion cylinder between the tip of the burner and a furnace wall, a pilot burner is inserted into the flow path of the waste plastic. Plastic burning burner.

[0010]

FIG. 1 is a longitudinal sectional view of an arc furnace, showing an embodiment in which a waste plastic combustion burner of the present invention is mounted on a furnace wall. FIG. 2A shows the first embodiment of the present invention.
FIG. 2B is a cross-sectional view of a waste plastic combustion burner according to the present invention, wherein FIG. 2B is a view taken along the line AA showing the tip of the combustion burner, and FIG. FIG. 3B is a cross-sectional view of the burner, and FIG. 3B is a BB arrow view showing the tip of the combustion burner, and when a line connecting the center of the oxygen flow path and the center of the fuel flow path passes through the center of the burner, FIG. ) Is a BB view showing the tip of the combustion burner, and the line connecting the center of the oxygen flow path and the center of the fuel flow path is shifted from the center of the burner. FIG. 4 shows the waste plastic according to the third aspect of the present invention. It is sectional drawing of a combustion burner.

Generally, an arc furnace comprises a furnace body 1 and a furnace lid 3 through which a movable electrode 2 for generating an arc 4 penetrates, as shown in FIG. 4
A panel 5 having a water cooling structure is attached so as to withstand the heat generated by the panel. Further, the furnace lid 3 is provided with a duct 6 for sucking gas generated in the furnace.

In an arc furnace, scrap 7 as a raw material is charged into the furnace so as to fill the furnace, and the scrap 7 is melted by the energy of the arc 4 generated in the center of the furnace. Further, in order to assist the melting of the scrap near the furnace wall far from the generation part of the arc 4, a combustion burner of oil or gaseous fuel is conventionally installed. In FIG. And a state where the waste plastic combustion burner 8 is installed. When the scrap 7 is being melted, particularly in the initial stage of melting, the scrap 7 is present in front of the burner 8, and the space 9 between the burner 8 and the scrap 7 is extremely small. Under such a condition, the injected waste plastic is not burned or is simply heated and collides with the scrap 7 near the furnace wall and rebounds, and burns after adhering to the panel 5 of the furnace wall, or burns near the furnace wall. Burn the waste plastic as much as possible inside the burner 8 so that it is not sucked from the duct 6 through the small space between the scrap 7 and the panel 5 of the furnace wall, and fully utilize the heat for melting the scrap. is important.

In the waste plastic combustion burner according to the first aspect of the present invention (FIG. 2 (a)), a flow path 10 in which waste plastic is gas-conveyed with air or the like and blown into an arc furnace at a central portion, and is provided on an outer periphery thereof. A fuel flow path 11, such as oil or gas, an oxygen flow path 12, and a cooling water flow path 13 are provided. FIG.
FIG. 2B shows an example in which the fuel flow path 11 and the oxygen flow path 12 are alternately arranged on the outer periphery of the waste plastic flow path 10 by eight systems. And the number of strains changes. In addition, flow path 1 of waste plastic
Since the cone-shaped flow correcting member 15 is provided at the spout No. 0 so that the waste plastic flow diverges toward the flow direction of the waste plastic, the flow correcting member 1 is provided.
The waste plastic whose flow has been changed in the outer peripheral direction of the burner by 5 blows out into a high-temperature flame 16 formed by fuel and oxygen which are respectively blown out from a fuel flow path 11 and an oxygen flow path 12, and further from the burner tip. Combustion can be efficiently performed in the space formed by the combustion tube 14 provided between the furnace walls. The flow correcting member 15 has a high thermal conductivity such as copper so as to enhance the cooling effect of the cooling water flowing through the cooling water passage 13 provided in the burner main body in order to prevent fusion of the waste plastic. It is desirable to use materials. Thus, even if the size of the waste plastic is several mm to several tens of mm, the waste plastic flow path 1
Since the flow of the waste plastic spreads divergently by the straightening member 15 installed in the cylinder 0, the waste plastic is reliably injected into the high-temperature flame 16 formed by fuel and oxygen, and is efficiently burned in the combustion tube 14.

FIG. 3 (a) shows a waste plastic combustion burner according to a second aspect of the present invention.
A fuel flow path 11 such as oil or gas, an oxygen flow path 1
2 and a cooling water channel 13 are provided. Oxygen channel 1
2 is disposed outside each fuel passage 11 and is connected to the oxygen passage 1
The second ejection port is inclined in the direction of the burner center axis, and the axis of the ejection port of the oxygen flow path 12 and the axis of the ejection port of the fuel flow path 11 intersect near the tip of the burner. Therefore, the high-temperature flame 16 formed by the fuel and oxygen ejected from the fuel channel 11 and the oxygen channel 12, respectively, is formed so as to cover the front of the ejection port of the waste plastic channel 10,
Waste plastic is spouted into the flame 16 and can be efficiently burned in a space defined by a combustion tube 14 provided between the furnace wall from the burner tip.
Thus, the size of the waste plastic is several mm to several tens m.
Even if it is m, fuel and oxygen are efficiently burned in the combustion cylinder 14 by covering the waste plastic from which it is jetted.

As shown in FIG. 3B, the oxygen flow path 12 may be radially arranged outside the fuel flow path 11 at the tip of the burner. In this case, the oxygen flow path 12
May be simply inclined in the direction of the burner center axis. Further, as shown in FIG. 3C, the oxygen flow path 12 is disposed outside the fuel flow path 11 so that the line connecting the centers of the flow paths is deviated from the center of the burner. Efficiency is also improved. In this case, the outlet of the oxygen flow path 12 is inclined in the burner center axis direction and also in the burner radial direction, and forms a swirling flow of the fuel and oxygen.
Further, FIGS. 3B and 3C show an example in which the fuel flow path 11 and the oxygen flow path 12 each have eight systems, but the number of systems is determined according to the flow rate ratio between fuel and oxygen. Can be arbitrarily selected.

According to the third aspect of the present invention, there is provided a waste plastic combustion burner (FIG. 4).
A fuel flow path 11 such as oil or gas, an oxygen flow path 1
2 and a cooling water channel 13 are provided. In addition, the pilot burner 17 is formed so as to form an acute angle with the flow path 10 of the waste plastic before the ejection port of the flow path 10 of the waste plastic.
Is provided, and a part of the waste plastic starts burning at the spout of the flow path 10, so that the fuel flow path 11, the oxygen flow path 1
2 does not collide with the high-temperature flame 16 formed by the fuel and oxygen ejected from the burner 16 near the burner.
Even if it is ejected to the center, it is possible to efficiently burn in the space defined by the combustion tube 14 provided between the furnace wall from the tip of the burner. Although the figure shows an example in which one pilot burner is arranged, a plurality of pilot burners may be installed according to the flow rate of waste plastic. The position of the pilot burner 17 in the flow path 10 of the waste plastic is preferably about 50 to 100 mm on the upstream side of the spout in order to prevent fusion of the waste plastic at the spout. As described above, even when the size of the waste plastic is several mm to several tens of mm, a part of the waste plastic starts to be burned by the pilot burner 17 installed in the waste plastic flow path 10, so that the waste plastic is disposed at the burner tip. It is efficiently burned in the combustion tube 14.

[0017]

The effects of the present invention are as follows.

(1) In the waste plastic combustion burner according to the first aspect of the present invention, the cone-shaped flow diverging toward the flow direction of the waste plastic flows into the discharge port of the waste plastic flow path at the center. A straightening unit is provided,
Waste plastic whose flow has been changed in the outer circumferential direction of the burner by this flow straightening member is jetted into a high-temperature flame formed by fuel and oxygen, and further formed by a combustion tube provided between the furnace wall and the tip of the burner. In order to burn efficiently in the space to be used, while using waste plastic of an economical size of about several mm to several tens of mm, the burning rate of waste plastic in the burner can be improved. The obtained heat can be effectively used for melting the scrap.

(2) In the waste plastic combustion burner according to the second aspect of the present invention, the oxygen flow path is disposed outside each fuel flow path, and the jet of the oxygen flow path is inclined in the direction of the burner center axis. Since the axis of the jet of the oxygen flow path and the axis of the jet of the fuel flow path intersect near the tip of the burner, they are formed by the fuel and oxygen ejected from the fuel flow path and the oxygen flow path, respectively. The generated high-temperature flame is formed so as to cover the front of the spout of the flow path of the waste plastic. As a result, waste plastic is ejected into the flame, and furthermore, it burns efficiently in the space formed by the combustion tube provided between the furnace wall and the tip of the burner.
The combustion rate of waste plastic in the burner can be improved while using waste plastic having an economical size of about m to several tens of mm, and the heat obtained by the combustion is effectively used for melting the scrap. It becomes possible.

(3) In the waste plastic combustion burner according to the third aspect of the present invention, a pilot burner is provided before the discharge port of the waste plastic flow path, and a part of the waste plastic is discharged from the discharge path of the flow path. To start burning in the part
Even if the fuel is injected into the center of the flame without colliding near the burner with the high-temperature flame formed by the fuel and oxygen ejected from the fuel flow path and the oxygen flow path, the combustion provided between the burner tip and the furnace wall It will burn efficiently in the space formed by the cylinder, and while using waste plastic of an economical size of several mm to several tens of mm, the combustion rate of waste plastic in the burner can be improved. The heat obtained by the combustion can be effectively used for melting the scrap.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view in which a waste plastic combustion burner of the present invention is attached to a furnace wall of an arc furnace.

FIG. 2 is a waste plastic combustion burner according to a first aspect of the present invention, in which (a) is a cross-sectional view of the burner and (b) is an AA view showing the combustion burner tip of (a).

FIG. 3 is a waste plastic combustion burner according to a second aspect of the present invention, wherein (a) is a cross-sectional view of the burner, and (b) is a BB arrow view showing the combustion burner tip of (a); If the line connecting the oxygen flow path center and the fuel flow path center passes through the burner center,
(C) is a view taken along the line BB showing the tip of the combustion burner, in which the line connecting the center of the oxygen flow path and the center of the fuel flow path is shifted from the center of the burner.

FIG. 4 is a sectional view of a waste plastic combustion burner according to a third aspect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace body 2 Movable electrode 3 Furnace lid 4 Arc 5 Water-cooled panel 6 Duct 7 Scrap 8 Burner 9 Space 10 Waste plastic flow path 11 Fuel flow path 12 Oxygen flow path 13 Cooling water flow path 14 Combustion cylinder 15 Flow straightening member 16 Flame 17 pilot burner

Claims (3)

[Claims] 1. A flow path for waste plastic which gas-conveys waste plastic into a central portion thereof and blows it into an arc furnace, a fuel flow passage which blows fuel into the arc furnace at an outer periphery thereof, and an oxygen flow which blows oxygen into the arc furnace. Plastic combustion burner having a cooling water passage for cooling the combustion burner and a combustion tube between the burner tip and the furnace wall. A waste plastic combustion burner for an arc furnace, comprising a cone-shaped flow correcting member for forming a flow. 2. A flow path of the waste plastic which gas-conveys the waste plastic into a central portion thereof and blows it into the arc furnace, a fuel flow passage which blows fuel into the arc furnace at an outer periphery thereof, and a cooling water flow passage which cools a combustion burner. A waste plastic combustion burner provided with a combustion cylinder between a tip of the burner and a furnace wall, an oxygen flow path for blowing oxygen into the arc furnace is arranged on an outer periphery of the fuel flow path, and a discharge port of the oxygen flow path is connected to the burner. A waste plastic combustion burner for an arc furnace, characterized by being inclined in the direction of a central axis. 3. A flow path of the waste plastic which gas-conveys the waste plastic into the central part and blows it into the arc furnace, a fuel flow path which blows fuel into the arc furnace at the outer periphery thereof, and an oxygen flow which blows oxygen into the arc furnace. An arc furnace, wherein a pilot burner is inserted into the waste plastic flow path in a waste plastic combustion burner having a cooling water flow path for cooling the combustion burner, and a combustion tube between the burner tip and the furnace wall. For waste plastic combustion burner.