TWI528010B - Igniting apparatus of sintering machine and igniting apparatus - Google Patents

Description

Ignition device and sintering machine for sintering machine

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.

Usually, the ignition device for the sintering machine for producing sintered ore is used for the upper surface of the sintered raw material layer which is loaded onto the pallet, and the heavy oil, coke oven gas or coke oven gas and blast furnace are injected from the burner. A fuel such as a gas mixture of gas and air are used to form a combustion flame, and the combustion flame is used to heat the sintered raw material layer to burn the coke in the sintered raw material layer.

Fig. 6 shows a sintering machine provided with the ignition device of the present invention. In the figure, 1 is a pallet, 2 is a wind box, 3 is an ignition apparatus, and mainly includes an ignition furnace 3a and a burner 3b, and 4 denotes a bottom layer (hearth) Layer) with a funnel, 5 indicates the material funnel.

The ignition device disclosed in Japanese Laid-Open Patent Publication No. SHO 59-200183 (Patent Document 1) includes: a fuel gas passage and a combustion air passage, which are sintered a plurality of nozzle holes that open in a direction in which the fuel gas supplied from the channels and the discharge flow of the combustion air intersect each other are separated along the longitudinal direction of each of the channels; . Further, Patent Document 1 proposes a technique for shortening a flame by injecting a fuel gas and air from a nozzle hole having a small diameter in an intersecting manner, thereby greatly improving energy loss. However, as described in Patent Document 1, if the combustion chamber is small and the burner height is low, there is an advantage that the heat dissipation of the furnace body is small and the amount of fuel used is suppressed. On the other hand, there is red heat when heating the sintered raw material layer. The possibility that the sintering material radiates heat to the radiant heat of the burner and the heat of the flame itself to damage the body of the burner.

In the Japanese Patent Publication No. 4-28826 (Patent Document 2), the burner end of the burner of the heat-resistant cast steel has a larger coefficient of linear expansion than that of the soft steel, so that the burner end during the operation is The elongation of the head is large, and the end of the burner is broken during the operation-recession process to shorten the life; it is revealed that the thermal expansion absorption slit is provided by dividing the burner end into a plurality of sheets in the width direction of the pallet, A technique for preventing breakage accompanying expansion and contraction. Patent Document 2 discloses that the flame is shortened by injecting the fuel gas and the air at right angles to each other, and the nozzle aperture is stepped from the center portion toward the end portion of the portion where the end portions of the pallet are excessively ventilated. The ground is enlarged, and the width direction is evenly ignited.

Then, due to factors such as the sudden stop of the sintering machine, the burner nozzle is thermally deformed and cracked, and the countermeasure against shortening the life of the burner is insufficient. .

Prior technical literature

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 59-200183

Patent Document 2: Japanese Patent Laid-Open No. 4-28826

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition device that is resistant to thermal stress even in an environment in which operation-rest is frequently repeated, and to extend the life of the ignition device of the sintering machine to reduce the maintenance frequency.

Features of the present invention for solving the above problems are as follows.

[1] An ignition device for a sintering machine, comprising: a passage for a fuel gas extending in a width direction of a pallet of the sintering machine; and an air passage for sandwiching the passage for the fuel gas on both sides of the passage for the fuel gas a plurality of nozzle holes are provided in the burner along the longitudinal direction of the fuel gas passage and the air passage, and the plurality of nozzle holes are directed toward the fuel gas from the fuel gas passage and from the above The combustion air is opened in a direction in which the combustion air flows in the air passage; and the burner cover covers the combustion environment below the nozzle hole; and the burner is a burner that welds the stainless steel plate.

[2] The ignition device of the sintering machine according to [1], wherein the fuel gas is sprayed The outflow and the discharge flow of the combustion air meet at an angle of 30 degrees or more and 60 degrees or less.

[3] The ignition device of the sintering machine according to [1], wherein the burner comprises a burner body and a burner end, and the burner body is integrally formed with the burner end.

[4] The ignition device of the sintering machine according to [1], wherein the plurality of pairs of nozzle holes include a fuel gas nozzle hole and an air nozzle hole, and the fuel gas nozzle hole is disposed at a center side of the burner and directed toward The outer side is open, and the air nozzle hole is opened inwardly on the outer side of the burner.

[5] A sintering machine which is provided with a gap which absorbs thermal elongation in the width direction of the holder of the sintering machine to arrange a plurality of sintering machines according to any one of [1] to [4]. In the ignition device, the sintering machine is disposed in such a manner that the end portions of the adjacent burners are thermally expanded by thermal expansion in a temperature environment in the ignition furnace.

According to the present invention, it is possible to provide an igniter for a sintering machine which achieves a uniform ignition intensity in the width direction of the sintering machine, a low original fuel unit, and the ignition device is operated even in an operation-rest environment frequently repeated. It is resistant to thermal stress.

1‧‧‧ pallet

2‧‧‧ bellows

3‧‧‧Ignition device

3a‧‧‧Ignition furnace

3b‧‧‧burner

4‧‧‧Floor layer funnel

5‧‧‧Material funnel

6‧‧‧fuel gas pipe

7‧‧‧Combustion air tube

8‧‧‧fuel gas supply pipe

8a‧‧‧Central flow path in the fuel gas pipe

9‧‧‧Air supply pipe

9a‧‧‧ tubular flow path for air tubes

10, 11‧‧‧ short tube

20, 20', 21, 21' ‧ ‧ nozzle holes

24 (24a, 24b) ‧ ‧ burner cover

26‧‧‧ beams

A‧‧‧flame width

Bb‧‧‧ burner body

Bt‧‧‧ burner end

F‧‧‧flame

L‧‧‧Distance from the front end of the burner to the surface of the sintered material layer

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view showing an ignition device of the present invention.

Fig. 2 is a front elevational view showing a portion of a sintering machine holder and an ignition device as a cross section.

3 is a cross-sectional view of a conventional ignition device.

Fig. 4 is a graph showing the relationship between the distance from the tip of the burner to the surface of the sintered raw material layer and the flame temperature.

Fig. 5 is a view showing a nozzle array at a front end portion of a burner.

Fig. 6 is a schematic configuration diagram of a sintering machine in which the apparatus of the present invention is installed.

The existing heat-resistant cast steel burner has to be divided into a burner body and a burner nozzle due to limitations of its material or processing method, and has the following problem: due to the reverse thermal deformation of the edge faces connecting the burner body and the burner nozzle. The strain at the edge portion is generated, and fuel gas and combustion air leakage caused by deterioration of the package and cutting are generated. As a result of active research, the present inventors have found that by changing the division type of the burner from heat-resistant cast steel to stainless steel in which the burner body and the burner nozzle are integrated, it is possible to provide an operation even if it is frequently repeated. - Ignition devices that are also resistant to thermal stress in the resting environment.

Table 1 shows the results of comparing the effects of material changes. Since the material of the burner is changed from heat-resistant cast steel to stainless steel in which the burner body and the burner nozzle are integrally formed, fuel leakage due to strain at the edge portion does not occur. Further, by reducing the thickness of the burner and the nozzle, the residual stress and the strain of the burner are reduced. As a result, it is possible to form a burner that can be used for a long period of time even in a use environment in which the operation-stop is frequently repeated.

Furthermore, the angle at which the discharge flows of the fuel gas and the combustion air intersect each other, and it has been found that by setting the angle to 60 degrees or less, the temperature of the nozzle portion can be lowered, and the nozzle portion can be prevented from being cracked. Hereinafter, description will be made by Table 2 and FIG.

Table 2 shows the results of evaluating the durability of an experimental burner having a burner width of 500 mm in an experimental combustion furnace. An iron plate is placed on the opposite side of the burner in the furnace to form a structure in which the burner receives radiant heat from below. The iron plate temperature is observed at a temperature of 1,300 ° C which is equivalent to the operation of a normal sintering machine, and at a temperature of 1,350 ° C when the operation of the sintering machine is changed, and the temperature is raised repeatedly, and the specified temperature is maintained for 30 minutes, and the temperature is lowered to observe the burner. The state of injury.

The thermal deformation disappears by changing the burner from the conventional heat-resistant cast steel split structure to the relatively thin welded stainless steel sheet. In the normal sintering machine operation, the surface temperature of the sintered raw material layer (corresponding to the furnace temperature during the test) is 1300 ° C, and cracking can be prevented by setting the burner material to stainless steel in a normal operation range. It can be seen that even if the temperature in the furnace is raised to 1,350 ° C by the fluctuation of the operation of the sintering machine, the angle at which the discharge flow of the fuel gas and the combustion air intersect each other can be made from the previous 90 degrees to 60 degrees and 40 degrees. With sharp angles, lower The nozzle portion temperature is used to reduce the crack frequency of the nozzle portion. As shown in Table 2, the crack was generated three times at a test temperature of 90 degrees, 6 times at 60 degrees, and 10 times at 40 degrees, and the durability was improved. In other words, it is found that the angle at which the discharge streams of the fuel gas and the combustion air intersect each other is 60 degrees or less, and the temperature of the nozzle portion can be lowered. Therefore, it is possible to prevent the nozzle portion from being cracked.

The relationship between the distance from the burner nozzle and the flame temperature is shown in Fig. 4. As the angle at which the fuel gas and the jet flow of the combustion air intersect each other is an acute angle, the flame portion having a temperature of 1300 ° C or more becomes long, and the distance between the burner and the heating surface must be lengthened. When the angle at which the discharge flows meet each other is in the range of 30 to 60 degrees, the temperature from the burner nozzle to 100 mm is greatly lowered. Therefore, it is suitable to reduce the temperature of the nozzle portion to prevent cracking of the nozzle portion.

If the angle at which the jets intersect each other is less than 30 degrees, the burner flame length becomes longer than 850 mm, the burner cover is enlarged, and the energy loss is increased, which is not preferable.

The burner produced by welding a stainless steel plate according to the present invention is preferably used by arranging a plurality of burners in the width direction of the sintering machine. By the width direction By arranging a plurality of burners, it is possible to change and adjust the combustion conditions in the width direction of the sintering machine with reference to the temperature distribution at the time of the operation, and to adjust the temperature distribution in the width direction even when the operating conditions such as the change in the distribution of the thickness of the raw material layer are changed.

In the present invention, it is preferred to provide a thermal expansion absorbing slit between the plurality of burners. The size of the thermal expansion slit is set so as to be in close contact with the end portion of the adjacent burner in the temperature environment of the ignition furnace in operation, and in the operation, there is no air that is attracted from the expansion slit and is ignited. The flame creates a mess.

In addition, by using a stainless steel plate for the burner to make the wall thinner and the burner lighter, the burner support structure can be simplified, and the installation work becomes easy.

Hereinafter, an embodiment of the present invention will be described.

In Fig. 2, a portion of the sintering machine tray and the ignition device is shown as a cross section. Bb denotes a burner body, Bt denotes a burner end, F denotes a flame, and L denotes a distance from a front end of the burner to a surface of the sintered raw material layer. The fuel gas supply pipe 8 and the air supply pipe 9 are provided over the entire width of the pallet, and the plurality of burners including the fuel gas pipe 6 and the combustion air pipe 7 are substantially parallel to the fuel gas supply pipe 8 and the air supply pipe 9. The way is to arrange the gaps of the thermal expansion slit size to arrange. The gas pipe 6 and the gas supply pipe 8 pass through the short pipe 10, and the air pipe 7 and the air supply pipe 9 are respectively connected to each other via the short pipe 11. The fuel gas supply pipe 8 and the air supply pipe 9 are supported by a beam 26.

In the lower part of the burner, the fuel gas supply pipe 8 of the burner and the burner The plurality of nozzle holes 20, 20', 21, 21' corresponding to the air supply pipe 9 are arranged in a plurality of sets of small-diameter nozzle holes in the tube axis direction as shown in FIG.

The fuel gas nozzle holes 20, 20' are opened toward the outer sides, and conversely, the air nozzle holes 21, 21' are opened inward, preferably with a fuel gas nozzle 20 (20') and an air nozzle 21 (21). The spray directions of ') are arranged to intersect each other to shorten the flame.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing an ignition device of the present invention. As described above, the burner body and the burner tip are integrally formed. Further, in the figure, a coke oven gas (COG) is exemplified as a fuel gas. θ in the figure indicates an angle at which the fuel gas and the jet of combustion air intersect each other. At this time, the angle at which the injection directions meet each other is large. The shortening of the burner flame length is advantageous in terms of reducing the energy loss by reducing the interval 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 injection directions intersect each other is small, the burner flame length becomes long, but the temperature of the nozzle portion is lowered, and it is difficult to cause cracking or thermal deformation of the nozzle portion. According to the above aspect, the angle at which the ejection directions intersect each other is preferably 30 degrees or more and 60 degrees or less. Further, in order to reduce the thermal influence, it is more preferable to coat the burner surface other than the tip end portion of the burner in which the nozzles are arranged with the refractory heat insulating material.

From both sides of the nozzle holes 21, 21', a burner cover 24a covering the combustion environment below the nozzle holes extends. By enclosing the high temperature range by making the burner cover smaller, energy loss can be reduced to perform operations in low fuel original units.

The apertures and the pitches of the nozzle holes 20, 20', 21, 21' can be appropriately adjusted according to the type of the fuel gas, the fuel gas, and the flow rate of the air, and the aperture is preferably 5 Mm~30mm, the pitch is preferably 10mm~40mm. In the case where the pitch is too large, there arises a problem that a portion having a low temperature is generated between the flames, causing uneven combustion of the sintered ore.

The fuel gas is preferably a gas using a calorific value of 2 kcal/Nm ³ to 25 kcal/Nm ³ . For example, M gas (mixed gas of blast furnace gas and coke oven gas), C gas (coke oven gas), liquefied natural gas, propane gas, or the like which is generally used in a cast iron plant can be used. If the calorific value of the fuel gas is less than 2 kcal/Nm ³ , the amount of fuel used increases, which is uneconomical. It is more preferable to use a fuel gas having a calorific value of 15 kcal/Nm ³ or less in terms of a self-cooling function of cooling the gas for combustion or air from the inside.

When the nozzle diameter and arrangement of the burner are optimized, if it is made of the conventional heat-resistant cast steel, the nozzle tip must be remade from the mold. However, by forming the welded structure of the stainless steel plate, the drill is only used for the nozzle. Part of the reworking and welding can be performed, and the adjustment can be inexpensive and the time is short, and even if the burner is cracked or broken, it can be easily repaired by welding. Further, if the thermal deformation is slight, a thin stainless steel plate is used, so that it can be used for short-time maintenance by correcting the thermal deformation.

In terms of uniform heating, it is also preferred to adjust the aperture according to the distribution of the air volume according to the width direction of the sintering machine. As long as the fuel gas and the air flow are adjusted for each of the plurality of burners arranged, the fire can be uniformly ignited in the width direction. . Further, the combustion conditions can be changed and adjusted for each burner with reference to the temperature distribution at the time of operation, and the width direction can be adjusted even if the operating conditions such as the change in the distribution of the thickness of the raw material layer change. Temperature distribution.

Further, each of the burners can be configured such that the vertical angle can be changed. The contact area between the surface of the sintered raw material layer and the flame front can be changed by raising and lowering the respective burners, so that the accuracy of uniform ignition can be improved. By changing the thickness of the sintered raw material layer, changing the pallet speed, changing the material properties, and changing the moisture in the raw material, the burner can be lifted and deflected, and the quality of the sintered ore, the yield of the product can be improved, and the fuel can be saved. Significant effect.

Example

In a sintering plant having a sintered ore production capacity of 11,000 tons per day, an ignition burner made of heat-resistant cast steel was changed to a burner obtained by welding a stainless steel plate (SUS316). The burner made of heat-resistant cast steel is a burner integrally formed with a width of 3950 mm over the width of the sintering machine. The burner obtained by welding the stainless steel plate is a burner with 800 mm width arranged in the transverse direction of the sintering machine. Settings.

The angle of the discharge flow of the fuel gas and the combustion air was 90 degrees in the burner made of heat-resistant cast steel, and was changed to 40 degrees in the burner made of stainless steel plate.

The fuel gas was operated using M gas so that the surface temperature of the sintered raw material layer reached 1300 °C.

As a result of the above-described operation by the igniter, when the heat-resistant cast steel burner is used, it is necessary to perform the correction of the thermal deformation of 6 times/year and the repair of the crack, and the maintenance time is 48 hours/year, but it is changed to stainless steel. After the steel plate is welded to the burner, only one time/year of thermal deformation can be corrected, and the repair time can be shortened to 40 hours / year, can greatly reduce the frequency of maintenance and repair time. In addition, the repair time is the repair time of the repair of the sintering machine equipment other than the burner.

6‧‧‧fuel gas pipe

7‧‧‧Combustion air tube

8‧‧‧fuel gas supply pipe

8a‧‧‧Central flow path in the fuel gas pipe

9‧‧‧Air supply pipe

9a‧‧‧ tubular flow path for air tubes

10, 11‧‧‧ short tube

20, 20', 21, 21' ‧ ‧ nozzle holes

24 (24a, 24b) ‧ ‧ burner cover

26‧‧‧ beams

A‧‧‧flame width

Bb‧‧‧ burner body

Bt‧‧‧ burner end

F‧‧‧flame

L‧‧‧Distance from the front end of the burner to the surface of the sintered material layer

Claims (5)

An ignition device for a sintering machine, comprising: a passage for a fuel gas extending in a width direction of a pallet of the sintering machine; and an air passage extending between the fuel gas passages via the passage for the fuel gas; burning a plurality of pairs of nozzle holes are provided along the longitudinal direction of the fuel gas passage and the air passage, and the plurality of pairs of nozzle holes are directed toward the fuel gas from the fuel gas passage and the air passage a combustion chamber is opened in a direction in which the discharge flow of the combustion air flows; and a burner cover covers the combustion environment below the nozzle hole; and the burner is a burner obtained by welding a stainless steel plate. The ignition device for a sintering machine according to claim 1, wherein the discharge flow of the fuel gas and the discharge flow of the combustion air meet at an angle of 30 degrees or more and 60 degrees or less. An ignition device for a sintering machine according to the above aspect of the invention, wherein the burner comprises a burner body and a burner end, and the burner body is integrally formed with the burner end. The igniter of the sintering machine according to claim 1, wherein the plurality of pairs of nozzle holes include a fuel gas nozzle hole and an air nozzle hole, and the fuel gas nozzle hole is disposed at a center side of the burner and directed toward The outside direction is open, The air nozzle hole is opened inwardly on the outer side of the burner. A sintering machine, in which a plurality of igniters of a sintering machine according to any one of claims 1 to 4 are arranged, in the width direction of the slab of the sinter, The sintering machine is provided in such a manner that the end portions of the adjacent burners are in close contact with each other by thermal expansion in a temperature environment in the ignition furnace.