JP5387803B1 - Sintering machine ignition device and sintering machine - Google Patents

Abstract

A fuel gas passage extending across the width direction of the pallet of the sintering machine, an air passage extending on both sides of the fuel gas passage, a jet flow of fuel gas from the fuel gas passage, and the air A burner provided with a plurality of nozzle holes opened in a direction in which the jet flow of combustion air from the gas passage meets each other along the length direction of the fuel gas passage and the air passage; And a burner hood for covering a combustion atmosphere below the nozzle hole, wherein the burner is a burner obtained by welding a stainless steel plate.

Description

  The present invention relates to an ignition device used in a sintering machine for producing sintered ore, and a sintering machine provided with the ignition device.

  In general, an ignition device of a sintering machine for producing sintered ore is composed of heavy oil, coke oven gas or coke oven gas and blast furnace gas from a burner toward the upper surface of a sintering raw material layer charged on a pallet. A combustion flame is formed by injecting a fuel such as a mixed gas and air and air, and the coke in the sintering raw material layer is burned by heating the sintering raw material layer with the combustion flame.

  FIG. 6 shows a sintering machine in which the ignition device according to the present invention is installed. In the figure, 1 is a pallet, 2 is a wind box, 3 is an ignition apparatus, and mainly comprises an ignition furnace 3a and a burner 3b, and 4 is a hearth layer. The hopper for 5 and a raw material hopper are shown.

  An ignition device disclosed in Japanese Patent Laid-Open No. 59-200193 (Patent Document 1) includes a fuel gas passage and a combustion air passage extending in the width direction of a pallet of a sintering machine, and fuel supplied from these passages. A burner provided with a plurality of nozzle holes that are opened in a direction in which the flow of gas and combustion air ejected each other, separated from each other along the length direction of each of the passages. Patent Document 1 discloses a technique for shortening a flame and greatly improving energy loss by injecting fuel gas and air so as to intersect with a small diameter nozzle hole. However, as in Patent Document 1, when the combustion chamber is small and the burner height is low, there is an advantage in that the amount of heat dissipated in the furnace body is small and the amount of fuel used is suppressed. On the other hand, There is a possibility of damaging the burner body due to the radiant heat from the raw material to the burner and the heat of the flame itself.

  On the other hand, Japanese Patent Laid-Open No. 4-28826 (Patent Document 2) discloses that since the coefficient of linear expansion of a burner tip made of heat-resistant cast steel is larger than that of mild steel, the elongation of the burner tip during operation is large, so In response to the problem of cracks entering the burner tip and shortening the service life, the thermal expansion absorption margin is provided by dividing the burner tip into multiple parts in the pallet width direction to prevent cracks associated with expansion and contraction. Technology is disclosed. Patent Document 2 discloses that the flame becomes a short flame by injecting the fuel gas and air so as to intersect at right angles, and the nozzle hole diameter is larger than the central portion with respect to the excessively ventilated portion of both ends of the pallet. Is increased stepwise to enable uniform ignition in the width direction.

  However, under the usage environment in which operation and stop are frequently repeated due to factors such as sudden stoppage of the sintering machine, thermal deformation and cracking of the burner nozzle still occur, and measures for shortening the burner life are insufficient.

JP 59-200193 A Japanese Patent Laid-Open No. 4-28826

An object of the present invention is to provide an ignition device that is resistant to thermal stress even in a use environment in which operation and stop are frequently repeated, and to extend the life of the ignition device of the sintering machine and reduce the repair frequency. .

The features of the present invention for solving the above-described problems are as follows.
[1]
A fuel gas passage extending across the width direction of the pallet of the sintering machine;
An air passage extending on both sides of the fuel gas passage;
The fuel gas passage and the air passage include a plurality of nozzle holes opened in a direction where the jet flow of the fuel gas from the fuel gas passage and the jet flow of the combustion air from the air passage meet each other. Burners provided apart along the length direction of
A burner hood that covers the combustion atmosphere below the nozzle hole;
Have
The burner is a burner obtained by welding a stainless steel plate.
Sintering machine ignition device.
[2] The ignition device for a sintering machine according to [1], wherein the jet flow of the fuel gas and the jet flow of the combustion air meet at an angle of 30 degrees to 60 degrees.
[3] The ignition device for a sintering machine according to [1], wherein the burner includes a burner body and a burner chip, and the burner body and the burner chip have an integral structure.
[4] The multiple pairs of nozzle holes include fuel gas nozzle holes and air nozzle holes,
The fuel gas nozzle hole is provided on the center side of the burner and opens in a direction facing the outside,
The air nozzle hole opens inwardly on the outside of the burner;
The ignition device for a sintering machine according to [1].

[5] A plurality of ignition devices for the sintering machine according to any one of [1] to [4] are arranged in the width direction of the pallet of the sintering machine with a gap for absorbing thermal elongation, and the temperature in the ignition furnace A sintering machine provided so that the ends of adjacent burners are in close contact with each other by thermal expansion in an atmosphere.

  According to the present invention, a igniter for a sintering machine having a uniform ignition strength in the width direction of the pallet of the sintering machine and a low fuel consumption rate, which is resistant to thermal stress even in a use environment in which operation and stop are frequently repeated. An ignition device can be provided.

It is sectional drawing of the ignition device by this invention. It is a front view which shows a sintering machine pallet and a part of ignition device as a cross section. It is sectional drawing of the conventional ignition device. It is a figure showing the relationship between the distance from a burner front-end | tip to the surface of a sintering raw material layer, and flame temperature. It is a figure showing the nozzle arrangement | sequence of a burner front-end | tip part. It is a schematic block diagram of the sintering machine which installs this invention apparatus.

  Conventional heat-resistant cast steel burners need to be divided into a burner body and a burner nozzle due to restrictions on the material and processing method. The flange part is repeatedly deformed due to repeated thermal deformation of the flange surface connecting the burner body and the burner nozzle. Distortion, deterioration of packing, fuel gas due to cutting, and combustion air leakage occurred. As a result of intensive studies by the present inventors, it was found that the burner is made of stainless steel in which the burner main body and the burner nozzle are integrated from the split type made of heat-resistant cast steel. It has been found that it is possible to provide an ignition device that is resistant to.

  Table 1 shows the results of comparing the effects of changing the material. Since the material of the burner was changed from heat-resistant cast steel to stainless steel with a burner body and burner nozzle, the fuel leakage due to flange distortion was eliminated. The residual stress and burner distortion were reduced by reducing the thickness of the burner and nozzle. As a result, it became a burner that can be used for a long period of time even in a use environment in which operation and suspension are frequently repeated.

  Furthermore, as a result of examining the angle at which the jets of fuel gas and combustion air meet each other, it is possible to reduce the temperature of the nozzle part by setting the angle to 60 degrees or less, and to prevent cracks in the nozzle part. I found it effective. Hereinafter, this will be described with reference to Table 2 and FIG.

  Table 2 shows the results of evaluating durability by installing an experimental burner having a burner width of 500 mm in an experimental combustion furnace. An iron plate is laid on the opposite surface of the burner in the furnace so that the burner receives radiant heat from below. The iron plate temperature is 1300 ° C equivalent to the normal sintering machine operation and 1350 ° C condition assuming the operation of the sintering machine fluctuating, repeating the specified temperature keep for 30 minutes and the temperature reduction, and the burner The damage situation of was observed.

  By changing the burner from a conventional heat-resistant cast steel split structure to a relatively thin welded stainless steel plate, thermal deformation is eliminated. In normal operation of the sintering machine, the surface temperature of the sintering material layer (corresponding to the furnace temperature during the test) is 1300 ° C, and cracks are prevented by making the burner material stainless in the normal operating range. Is possible. Even if the furnace temperature rises to 1350 ° C due to fluctuations in the operation of the sintering machine, the angle at which the jets of fuel gas and combustion air meet each other is made to meet an acute angle of 90 degrees to 60 degrees and 40 degrees. It was found that the crack frequency of the nozzle part can be reduced by lowering the nozzle part temperature. As shown in Table 2, cracks occurred at 90 degrees with 3 tests, whereas durability at 6 degrees at 60 degrees and 10 times at 40 degrees. That is, it has been found that when the angle at which the jets of fuel gas and combustion air meet each other is set to 60 degrees or less, the temperature of the nozzle portion can be lowered, so that there is an effect of preventing cracks in the nozzle portion.

The relationship between the distance from the burner nozzle and the flame temperature is shown in FIG. As the angle at which the jets of fuel gas and combustion air meet each other becomes sharper, the flame portion having a temperature of 1300 ° C. or higher becomes longer, and the distance between the burner and the heating surface needs to be increased. When the angle at which the ejected flows meet each other is in the range of 30 to 60 degrees, the temperature from the burner nozzle to 100 mm is greatly reduced, which is suitable for lowering the nozzle part temperature and preventing the occurrence of cracks in the nozzle part.
If the angle at which the jet flows meet each other is less than 30 degrees, the burner flame length becomes as long as more than 850 mm, which is not preferable because the burner hood becomes larger and energy loss increases.

  It is preferable that a plurality of burners manufactured by welding the stainless steel plate of the present invention are used side by side in the width direction of the sintering machine. By arranging multiple burners in the width direction, the combustion conditions in the width direction of the sintering machine can be individually changed and adjusted by looking at the temperature distribution during operation, and the operation conditions such as the distribution of the raw material layer thickness change. However, the temperature distribution in the width direction can be adjusted.

  In the present invention, it is preferable to provide a thermal expansion absorption margin between a plurality of burners. If the temperature of the thermal expansion allowance is set so that the end of the adjacent burner is in close contact with the thermal expansion in the temperature atmosphere in the ignition furnace during operation, ambient air is sucked from the expansion allowance during operation and ignited. The frame is not disturbed.

  In addition, since the burner has been reduced in weight by using a stainless steel plate for the burner, the burner support structure can be simplified and the installation work is facilitated.

Hereinafter, an embodiment of the present invention will be described.
FIG. 2 shows a cross section of a part of the sintering machine pallet and the ignition device. Bb is a burner body, Bt is a burner tip, F is a flame, and L is the distance from the burner tip to the surface of the sintered raw material layer. A fuel gas supply pipe 8 and an air supply pipe 9 are provided over the entire width of the pallet, and a plurality of burners including the fuel gas pipe 6 and the combustion air pipe 7 are substantially the same as the fuel gas supply pipe 8 and the air supply pipe 9. They are arranged in parallel with a gap for thermal expansion. The gas pipe 6 and the gas supply pipe 8 are individually communicated with each other via a short pipe 10, and the air pipe 7 and the air supply pipe 9 are individually communicated with each other via a short pipe 11. The fuel gas supply pipe 8 and the air supply pipe 9 are supported by a girder 26.

  In the lower part of the burner, a large number of nozzle holes 20, 20 ', 21, 21' respectively corresponding to the fuel gas supply pipe 8 and the air supply pipe 9 of the burner are shown in FIG. Many sets are arranged in the axial direction.

  The fuel gas nozzle holes 20 and 20 ′ are opened in a direction facing both outer sides, and the air nozzle holes 21 and 21 ′ are opened inward, and the fuel gas nozzle 21 (21 ′) and the air nozzle are opened. It is preferable to arrange so that the injection directions of 20 (20 ′) intersect each other and to make the frame a short flame.

  FIG. 1 shows a cross-sectional view of an ignition device according to the present invention. As described above, the burner body and the burner tip are integrated. In this figure, COG is illustrated as the fuel gas. In the figure, θ represents an angle at which the jets of fuel gas and combustion air meet each other. At this time, the larger the angle at which the injection directions intersect each other, the shorter the burner flame length, and it is advantageous to reduce the energy loss by narrowing the distance between the upper surface of the sintered raw material layer on the pallet and the burner. On the other hand, when the angle at which the jetting directions intersect with each other is small, the burner flame length becomes long, but the temperature of the nozzle portion becomes low, and the problem of nozzle portion cracking and thermal deformation hardly occurs. Accordingly, the angle at which the injection directions meet each other is preferably 30 degrees or more and 60 degrees or less. In order to further reduce the thermal influence, it is more preferable to cover the burner surface other than the burner tip where the nozzles are arranged with a refractory heat insulating material.

  A burner hood 24a that covers the combustion atmosphere below the nozzle hole extends from both sides of the nozzle holes 21 and 21 '. By reducing the size of the burner hood and enclosing the high temperature range, it is possible to reduce energy loss and operate with low fuel consumption.

  The hole diameters and pitches of the nozzle holes 20, 20 ′, 21, and 21 ′ should be appropriately adjusted according to the type of fuel gas and the flow rates of the fuel gas and air, but the hole diameter is 5 to 30 mm and the pitch is 10 -40 mm is preferred. When the pitch is too wide, there is a problem that a portion having a low temperature is generated between the flames and the sintered ore can be burned unevenly.

The fuel gas is preferably a gas having a calorific value of 2 to 25 kcal / Nm ³ . For example, it is possible to use M gas (mixed gas of blast furnace gas and coke oven gas), C gas (coke oven gas), liquefied natural gas, propane gas, etc. that are usually used in steelworks. If the calorific value of the fuel gas is less than 2 kcal / Nm ³ , the amount of fuel used increases, which is uneconomical. From the viewpoint of a self-cooling function of cooling from the inside with combustion gas / air, it is more preferable to use a fuel gas having a calorific value of 15 kcal / Nm ³ or less.

  When optimizing the nozzle hole diameter and arrangement of the burner, it was necessary to remanufacture the nozzle tip from the mold in the conventional heat-resistant cast steel, but by using a stainless steel plate welded structure, only the nozzle part can be drilled. It only has to be reworked and welded, making adjustments inexpensive and possible in a short period of time, and even if the burner is cracked or cracked, it can be easily repaired by welding. Also, if the thermal deformation was slight, a thin stainless steel plate was adopted, so that it could be reused with a short repair by correcting the thermal deformation.

  Adjusting the hole diameter according to the distribution of the passing airflow in the width direction of the sintering machine bed is also preferable in terms of uniform heating, but if the fuel gas and air flow rates are adjusted for each burner arranged in multiple units, uniform ignition in the width direction is possible. Possible. In addition, it is possible to change and adjust the combustion conditions for each burner by looking at the temperature distribution during operation, and the temperature distribution in the width direction can be adjusted even if the operating conditions such as the distribution of the raw material layer thickness change. It becomes.

Moreover, you may comprise each burner so that an up-down angle change is possible. By raising and lowering and tilting each burner, the contact area between the surface of the sintering raw material layer and the frame tip can be made variable, so that the accuracy of uniform ignition can be improved. Changes in sintering material layer thickness, the pallet speed change, material properties, depending on the changes in the raw material moisture, by lifting and tilting the burner, the quality of sintered ore, improvement of the yield, such as fuel economy sensible A remarkable effect is obtained.

In a sinter factory with a sinter production volume of 11000t per day, the ignition burner made of heat-resistant cast steel was changed to a burner made by welding a stainless steel plate (SUS316). The burner made of heat-resistant cast steel was a burner integrally formed over the entire sintering machine width of 3950 mm. However, five burners welded with stainless steel plates were arranged side by side in the transverse direction of the sintering machine pallet.
The angle of the jet flow of fuel gas and combustion air was 90 degrees for the heat-resistant cast steel burner, but was changed to 40 degrees for the stainless steel burner.
M gas was used as the fuel gas, and the operation was performed so that the surface temperature of the sintering material layer was 1300 ° C.

  As a result of the operation by the above ignition device, when using a heat-resistant cast steel burner, 6 times / year of thermal deformation correction and crack repair are required, and the repair time was 48 hours / year. After changing to a burner that had been processed, the repair time could be shortened to 40 hours / year only by correcting the thermal deformation once per year, and the repair frequency and repair time could be greatly reduced. In addition, repair time is repair time also including repair of sintering machine facilities other than a burner.

Bb Burner body Bt Burner tip F Flame L Distance from burner tip to sintering raw material layer surface 1 Pallet 2 Windbox 3 Ignition device 3a Ignition furnace 3b Burner 4 Floor hopper 5 Raw material hopper 6 Fuel gas pipe 7 Combustion air pipe 8 Fuel gas supply pipe 8a Center flow path in fuel gas pipe 9 Air supply pipe 9a Tubular flow path of air pipe
10, 11 Short tube
17, 17 'flange
20, 20 ', 21, 21' Nozzle hole
24 (24a, 24b) Burner food
26 Girder

Claims (5)

A fuel gas passage extending across the width direction of the pallet of the sintering machine;
An air passage extending on both sides of the fuel gas passage;
The fuel gas passage and the air passage include a plurality of nozzle holes opened in a direction where the jet flow of the fuel gas from the fuel gas passage and the jet flow of the combustion air from the air passage meet each other. Burners provided apart along the length direction of
A burner hood that covers the combustion atmosphere below the nozzle hole;
Have
The burner is a burner obtained by welding a stainless steel plate.
Sintering machine ignition device.
2. The ignition device for a sintering machine according to claim 1, wherein the jet flow of the fuel gas and the jet flow of the combustion air meet at an angle of 30 degrees or more and 60 degrees or less.
2. The ignition device for a sintering machine according to claim 1, wherein the burner includes a burner body and a burner chip, and the burner body and the burner chip have an integral structure.
The multiple pairs of nozzle holes are composed of fuel gas nozzle holes and air nozzle holes,
The fuel gas nozzle hole is provided on the center side of the burner and opens in a direction facing the outside,
The air nozzle hole opens inwardly on the outside of the burner;
The ignition device for a sintering machine according to claim 1. A plurality of ignition devices for the sintering machine according to any one of claims 1 to 4 are arranged in the width direction of the pallet of the sintering machine with a gap for absorbing thermal elongation, and are adjacent to each other in an ignition furnace temperature atmosphere. The sintering machine provided so that the end part of the burner to be brought into close contact by thermal expansion.

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