JP3552976B2 - melting furnace - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a fuel ejection unit that ejects gaseous fuel into a space above a region where a melt exists in a melt tank,
An oxygen-containing gas supply path for supplying the oxygen-containing gas obliquely downward is provided through a oxygen-containing gas supply port located above the fuel ejection portion and to a combustion region of the gas fuel ejected from the fuel ejection portion. Melting furnace.
[0002]
[Prior art]
In such a melting furnace, a gas ejecting portion configured to eject gaseous fuel (hereinafter, may be referred to as a gas-fuel-only firing type fuel ejecting portion) is used to supply gas to a space above a region where a melt exists in a melting tank. The fuel is ejected, and the oxygen-containing gas supply path passes the oxygen-containing gas obliquely downward with respect to the combustion area of the gas fuel ejected from the fuel ejection section through the oxygen-containing gas supply port located above the fuel ejection section. It is configured to supply the gaseous fuel and the oxygen-containing gas for combustion so as to be brought into contact with each other, burn the raw material, heat and melt the raw material, and store the melt in a melting tank.
[0003]
By the way, in such a melting furnace, conventionally, in addition to the fuel jet section of the gas fuel firing type, a fuel jet section of the liquid fuel firing type configured to jet the liquid fuel is provided. There is a type provided with a co-firing type fuel ejection section configured to eject gas fuel for atomizing the fuel. However, in those provided with the fuel ejection section of the liquid fuel only combustion type or the mixed combustion type, since the momentum of the fuel ejected from the fuel ejection section is large, the surface portion of the melt stored in the melting tank is washed away, In addition, since the raw material supplied in a state of being floated on the melt stored in the melt tank is easy to be washed away, there is a possibility that the melt cannot be obtained properly. On the other hand, it was necessary to incline greatly upward. For this reason, the flame tends to move away from the upper surface of the region where the melt exists in the melting tank, so that the heating efficiency is reduced.Moreover, since the flame tends to approach the ceiling of the furnace body, the temperature of the ceiling increases. As a result, there is a disadvantage that the durability is reduced.
[0004]
In the case of providing the fuel jet portion of the gas fuel exclusive combustion type as in the present application, compared with the case of providing the fuel jet portion of the liquid fuel exclusive combustion type or the mixed combustion type as described above, the fuel injected from the fuel Since the momentum is small, it is advantageous in preventing the flushing of the surface portion of the melt stored in the dissolving tank or the flushing of the raw material floating on the melt stored in the dissolving tank. .
Therefore, the fuel ejection section of the gas fuel combustion type can reduce the upward inclination angle with respect to the horizontal direction of the fuel ejection direction, as compared with the liquid fuel combustion type or the mixed combustion type fuel ejection section, thereby improving the heating efficiency. In addition, this is advantageous in improving durability due to a decrease in the temperature of the furnace body ceiling.
[0005]
[Problems to be solved by the invention]
However, in the conventional fuel-fuel-burning type fuel injection section, although it is advantageous in preventing the melt in the melting tank and the raw material floating in the melt from being washed away, the fuel injection Since the standard of the gas fuel ejection direction of the part is not set, it is possible to prevent the melt in the melting tank and the raw material floating in the melt from being washed away, and to obtain the melt appropriately. There is a possibility that both heating efficiency and durability cannot be effectively improved, and there is room for improvement.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to effectively improve both heating efficiency and durability while appropriately obtaining a melt. It is in.
[0007]
[Means for Solving the Problems]
[Invention of claim 1]
The characteristic configuration according to claim 1, wherein a gas fuel ejection angle of the fuel ejection portion is horizontal in relation to a bottom downward inclination angle at which a bottom of the oxygen-containing gas supply passage is inclined downward with respect to a horizontal direction. The upper angle is set to an angle obtained by adding the bottom downward inclination angle to the upper side, and the angle is set to be within an angle range having the horizontal direction as the lower limit.
[0008]
The inventors of the present invention, in order to improve the heating efficiency and lower the temperature of the furnace body ceiling while preventing the melt in the melting tank and the raw material floating in the melt from being washed away, We have studied diligently about the direction of gas fuel injection at the fuel injection unit of the gas fuel combustion type.
Then, among the oxygen-containing gas supplied by the oxygen-containing gas supply path, the one guided at the bottom of the oxygen-containing gas supply path to the combustion zone of the gas fuel ejected from the fuel ejection section is first Since it comes into contact with the gaseous fuel injected from the fuel injection part and greatly contributes to the combustion of the gaseous fuel, the heating is performed while preventing the molten material in the melting tank and the raw material floating in the molten material from being washed away. In order to improve the efficiency and reduce the temperature of the furnace body ceiling, when setting the reference of the gas fuel ejection angle of the fuel ejection part, the bottom of the oxygen-containing gas supply path is inclined downward with respect to the horizontal direction. It has been found that setting in relation to the bottom downward inclination angle is effective.
And the gas fuel ejection angle of the fuel ejection section, in relation to the bottom downward inclination angle of the oxygen-containing gas supply path, the upper limit of the angle obtained by adding the bottom downward inclination angle above the horizontal direction, and, When the angle is set within the horizontal range as the lower limit, the flame melts while preventing the molten material in the melting tank and the raw material floating on the molten material from flowing away in a state where the flame is formed stably. It has been found that it is possible to keep the distance from the upper surface of the region where the melt is present in the tank too close to the ceiling of the furnace body. That is, the direction in which the gas fuel is ejected from the fuel ejection section is set in the horizontal direction, or in the direction inclined upward with respect to the horizontal direction at an angle equal to or smaller than the above-mentioned bottom downward inclination angle.
By the way, if the gas fuel ejection direction of the fuel ejection part is set to a direction slightly inclined downward with respect to the horizontal direction, the gas fuel ejected from the fuel ejection part will be easily scattered, the flame will be disturbed and the flame will be stabilized Difficult to form.
Therefore, while preventing the melt in the melting tank and the raw material floating on the melt from being washed away, the fuel ejection section is designed to improve the heating efficiency and effectively lower the temperature of the furnace body ceiling. Since the standard of the gas fuel ejection angle of the above can be clearly set, it has become possible to effectively improve both the heating efficiency and the durability while appropriately obtaining the melt.
[0009]
[Invention of claim 2]
The feature configuration according to claim 2 is configured such that the fuel ejection portion includes a central ejection hole and a plurality of peripheral ejection holes around the center ejection hole,
The gas fuel ejection direction of each of the plurality of peripheral ejection holes is configured to be parallel or substantially parallel to the gas fuel ejection direction of the central ejection hole,
The distance between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole is 0.5 times or more the diameter of the peripheral ejection hole, and the diameter of the central ejection hole and the diameter of the peripheral ejection hole are added. It is configured to be 1.5 times or less of the value,
The configuration is such that 50 to 75% of the total amount of gas fuel ejected from the fuel ejection portion is ejected from the central ejection hole, and the remainder is ejected from the plurality of peripheral ejection holes.
[0010]
That is, when the fuel ejection portion is configured to include a central ejection hole and a plurality of peripheral ejection holes around the central ejection hole, the gas fuel flow ejected from the plurality of peripheral ejection holes allows the fuel ejection portion to provide a gas fuel ejected from the central ejection hole. By shutting off the supply of the oxygen-containing gas for combustion, so-called slow combustion can be performed. Therefore, a flame having a high luminance is formed, the amount of radiant heat is increased, and the flame temperature is lowered to reduce NOx. It has been known that the conversion can be achieved.
However, conventionally, the gap between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole, and the gas fuel ejection amount ratio between the central ejection hole and the plurality of peripheral ejection holes are not properly set. There is a possibility that the NOx generation amount may not be appropriately reduced, and there is room for improvement.
[0011]
The inventors of the present invention have made intensive studies to further reduce NOx when the fuel ejection portion is configured to have a central ejection hole and a plurality of peripheral ejection holes around the center ejection hole. Each of the gas fuel ejection directions of the ejection holes is configured so as to be parallel or substantially parallel to the gas fuel ejection direction of the center ejection hole, and the interval between the opening edge of the center ejection hole and the opening edge of the peripheral ejection hole is changed. And how the amount of NOx generated varies when the gas fuel injection amount ratio between the central outlet and the plurality of peripheral outlets changes. Was found to change.
The interval between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole is 0.5 times or more of the diameter of the peripheral ejection hole, and the value obtained by adding the diameter of the central ejection hole and the diameter of the peripheral ejection hole is 1 .5 times or less, wherein 50-75% of the total gas fuel ejection from the fuel ejection portion is ejected from the central ejection hole, and the remainder is ejected from a plurality of peripheral ejection holes. Then, it has been found that slow combustion can be effectively performed, which is preferable in reducing the generation amount of NOx.
[0012]
In other words, when the distance between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole is smaller than 0.5 times the diameter of the peripheral ejection hole, the gas fuel ejected from the plurality of peripheral ejection holes is ejected from the central ejection hole. It becomes difficult to separate from the gaseous fuel injected from the hole, and the auxiliary flame formed at the peripheral outlet is separated from the main flame formed at the central outlet, and the separation state of the auxiliary flame decreases. Therefore, it is considered that the generation amount of NOx increases.
When the distance between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole is wider than 1.5 times the value obtained by adding the diameter of the central ejection hole and the diameter of the peripheral ejection hole, a plurality of peripheral ejection holes are formed. It is considered that the amount of NOx generated increases because the effect of shutting off the supply of the oxygen-containing gas for combustion with respect to the gas fuel ejected from the central ejection hole due to the gas fuel stream ejected from the fuel tank decreases.
When the ratio of the ejection amount from the central ejection hole to the total ejection amount is out of the range of 50 to 75%, the gas fuel ejected from the plurality of peripheral ejection holes is combined with the gas fuel ejected from the central ejection hole. Since it becomes difficult to separate the auxiliary flame and the separated state of the supplementary flame decreases, the generation amount of NOx is considered to increase.
[0013]
Accordingly, the interval between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole, and the gas fuel ejection amount ratio between the central ejection hole and the plurality of peripheral ejection holes are set under the above conditions, The contact state between the fuel gas and the oxygen-containing gas for combustion can be stably reduced by providing the fuel ejection section having appropriately reduced NOx at the standard gas fuel ejection angle as set forth in claim 1. Thus, it is possible to set an appropriate state in which NOx reduction can be further promoted, and in conjunction with this, NOx reduction can be further achieved.
As a result, it is possible to effectively improve both the heating efficiency and the durability while appropriately obtaining the melt, and to further promote the reduction of NOx.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the present invention is applied to a glass melting furnace will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the glass melting furnace includes a melting tank 2 having a rectangular shape in a plan view at a lower portion in a furnace body 1, and a furnace wall 4 on one side of the melting tank 2. The gaseous fuel is placed above the region where the molten glass (corresponding to the molten material) is present in the melting tank 2, and is supplied to a space 3 (hereinafter sometimes simply referred to as a furnace) 3 above the region where the molten glass is present. A gas burner 7 is provided as a fuel ejecting portion to be ejected, and a combustion area of gas fuel ejected from the gas burner 7 is passed through an air port (so-called port) 5 serving as an oxygen-containing gas supply port located above the gas burner 7. An air supply passage 6 is provided as an oxygen-containing gas supply passage for supplying air obliquely downward as an oxygen-containing gas, and is configured as a so-called underport type.
[0015]
The gas burner 7 is provided on the furnace wall 4 for installing a gas burner so as to eject gas fuel toward the furnace wall 4 facing the furnace wall 4 for installing the gas burner. At the end of the furnace wall 4 on the side of the gas burner 7 connected to one end in the direction, the glass raw material is floated on the molten glass stored in the melting tank 2 in a direction substantially perpendicular to the direction of gas fuel ejection from the gas burner 7. A supply port 4i for supply is provided, and a work tank 9 is provided outside the furnace wall 4 facing the furnace wall 4 for installing a gas burner, and a furnace wall 4 between the work tank 9 and the melting tank 2 is provided. An opening 4e for communication between the melting tank 2 and the work tank 9 is formed in the hearth of the melting tank 2 to form a so-called end port type.
That is, the glass raw material is put into the melting tank 2 from the input port 4i, and the glass raw material is melted while flowing in a meandering manner toward the opening 4e side, and is cleaned through the opening 4e of the hearth. The glass is configured to be guided to the work tank 9.
[0016]
In a so-called end port type glass melting furnace, a glass raw material is supplied to the melting tank 2 so as to flow in a direction orthogonal to a direction in which fuel is jetted from a fuel jetting section. Therefore, conventionally, as a fuel ejection unit, an oil burner (corresponding to a fuel ejection unit of a liquid fuel combustion type) that ejects liquid fuel, and a gas atomization burner that ejects liquid fuel and gas fuel for atomizing the same are used. In the case of using a co-firing type fuel ejection part), the glass material flowing through the melting tank 2 is easily pushed out in the direction of the ejection hole 4e, so that it is necessary to set a large upward fuel ejection angle with respect to the horizontal direction. In addition, problems such as a low heating efficiency and a high durability of the furnace body 1 due to a high temperature at the ceiling portion have become remarkable.
[0017]
Two air ports 5 are provided on the furnace wall 4 for installing the gas burner in the left-right direction toward the furnace wall 4 facing the furnace wall 4, and the air supply passages 6 correspond to the respective air ports 5. It is provided.
Three gas burners 7 are provided side by side in the left-right direction corresponding to each air port 5. Although the six gas burners 7 are similarly configured, in the following description, three gas burners 7 corresponding to the right air port 5 in the left-right direction will be referred to as a right gas burner 7 and a left air port 5. May be distinguished from the left gas burner 7 in some cases.
Two heat storage chambers 8 are arranged side by side in the left-right direction on the side of the furnace wall 4 for installing a gas burner of the furnace main body 1, and each air supply path 6 communicates with each heat storage chamber 8.
[0018]
The left and right gas burners 7 alternately repeat the injection and stoppage of the gas fuel G every predetermined time (about 15 to 30 minutes), and from the air port 5 on the side of the gas burner 7 which ejects the gas fuel G, Combustion air A preheated to a high temperature (about 900 to 1000 ° C.) through the heat storage chamber 8 is supplied into the furnace 3, and the air outlet 5 on the side of the gas burner 7 where the injection of the gas fuel G is stopped. Is designed to discharge the combustion gas E in the furnace 3 and perform so-called alternating combustion in which the right and left gas burners 7 are alternately burned. 1 and 2 show a state in which the right gas burner 7 is burning and the left gas burner 7 is extinguished.
[0019]
Combustion air A is supplied to the combustion area of the gas fuel G ejected from the gas burner 7 from the air port 5 on the side of the gas burner 7 ejecting the gas fuel G, so that the gas fuel contacts the combustion air. Then, a flame (bright flame) F having a long length and high brightness is formed, and the glass material in the melting tank 2 is melted by the radiant heat of the flame F. The ceiling of the furnace body 1 is formed in an arch shape, and reflects the radiant heat of the flame F.
The combustion gas E in the furnace 3 flows into the heat storage chamber 8 from the air port 5 on the side of the gas burner 7 in which the injection of the gas fuel G is stopped, passes through the heat storage material, and the exhaust heat is recovered by the heat storage material. After being exhausted.
In the heat storage chamber 8, when the combustion gas E is discharged, the exhaust heat is recovered from the combustion gas E to the heat storage material to store the heat, and when the combustion air A is supplied, the combustion is performed by the heat storage of the heat storage material. Preheat the working air A. Then, the combustion air A thus preheated flows through the air supply passage 6 and is supplied from the air port 5 to the inside 3 of the furnace.
[0020]
The air supply path 6 is formed such that the cross section of the flow path (cross section perpendicular to the flow direction) has a rectangular shape, for example. Then, as shown in FIG. 3, the angle at which the bottom of the air supply path 6 is inclined downward with respect to the horizontal direction is defined as a bottom downward inclination angle x, and the upper part of the air supply path 6 is inclined downward with respect to the horizontal direction. Assuming that the angle is the upper downward inclination angle y, the bottom downward inclination angle x is within the range of 10 ° ≦ x ≦ 20 ° under the condition that the bottom downward inclination angle x <the upper downward inclination angle y. Are set within the range of 20 ° ≦ y ≦ 25 °, respectively.
The upper downward inclination angle y is set to be larger than the bottom downward inclination angle x in order to suppress the high-temperature combustion air supplied from the air port 5 from rising upward.
[0021]
The gas fuel ejection angle z of the gas burner 7 is obtained by adding the bottom downward inclination angle x upward with respect to the horizontal direction in relation to the bottom downward inclination angle x where the bottom of the air supply passage 6 is inclined downward with respect to the horizontal direction. The angle is set as an upper limit and the horizontal direction is set as a lower limit within an angle range.
[0022]
In the present embodiment, the bottom downward inclination angle x is set to 10 °, the upper downward inclination angle y is set to 20 °, and the gas fuel ejection angle z is set to 8 °.
The height of the nozzle at the tip of the gas burner 7 with respect to the upper surface of the molten glass stored in the melting tank 2 is set to about 30 cm. When the height of the nozzle at the tip of the gas burner 7 with respect to the upper surface of the molten glass stored in the melting tank 2 is set to about 30 cm, the heating efficiency is improved and the glass raw material floating in the melting tank 2 is removed by the gas burner 7. It is preferable to prevent flushing with a flame.
[0023]
Next, the gas burner 7 will be described with reference to FIGS. 6A is a view in the gas fuel ejection direction Ga of the nozzle 72, and FIG. 6B is a cross-sectional view in the gas fuel ejection direction Ga of the nozzle 72.
The gas burner 7 has a central outlet 72a and a plurality of peripheral outlets 72b around the central outlet 72a. From these outlets 72a and 72b, a gas fuel G such as LPG or city gas containing methane as a main component is supplied to the furnace. It gushes out to three.
[0024]
In the first embodiment, the gas fuel ejection direction of the plurality of peripheral ejection holes 72b in the gas burner 7 is configured to be parallel or substantially parallel to the gas fuel ejection direction of the center ejection hole 72a. The distance between the opening edge and the opening edge of the peripheral ejection hole 72b is at least 0.5 times the diameter of the peripheral ejection hole 72b, and is 1.5 times the value obtained by adding the diameter of the central ejection hole 72a and the diameter of the peripheral ejection hole 72b. 50% to 75% of the total amount of gas fuel injected from the gas burner 7 is ejected from the central ejection hole 72a, and the remainder is ejected from a plurality of peripheral ejection holes 72b. It is.
[0025]
The gas burner 7 includes a cylindrical burner main body 71, a nozzle 72 located at the tip of the burner main body 71, and a water-cooled holder 73 screwed to the tip of the burner main body 71 in a state of being fitted to the nozzle 72. It is composed.
[0026]
The nozzle 72 has a cylindrical central ejection hole 72a in which the axis Pa becomes coaxial with the columnar material, and the nozzle 72 has a concentric circle with the axis Pa of the central ejection hole 72a. A plurality of circular peripheral ejection holes 72b are formed at equal intervals along the axis so that each has the same diameter and each axis Pb is parallel to the axis Pa of the central ejection hole 72a. is there. The number of the peripheral ejection holes 72b is set to a number within a range of 6 to 16, but is set to 16 in the first embodiment.
[0027]
Further, the distance between the center of the tip opening of the central ejection hole 72a and the center of the tip opening of each peripheral ejection hole 72b (hereinafter, may be simply referred to as the distance between the center of the central ejection hole 72a and the center of the peripheral ejection hole 72b). A) is D, and the diameter of the tip opening of the central ejection hole 72a is d. _a And the diameter of the opening at the tip of the peripheral ejection hole 72b is d. _b Then, D is set so as to fall within the range of Expression 1 below.
[0028]
(Equation 1)
(1/2) × (d _a + D _b ) + (1/2) × d _b ≦ D ≦ 2 × (d _a + D _b )
[0029]
When D is set so as to fall within the range of Expression 1, the distance between the opening edge of the central ejection hole 72a and the opening edge of each peripheral ejection hole 72b is determined by the diameter d of the peripheral ejection hole 72b. _b 0.5 times or more of the value obtained by adding the diameter of the central ejection hole 72a and the diameter of the peripheral ejection hole 72b (d _a + D _b ) Is 1.5 times or less.
[0030]
The diameter of the central ejection hole 72a and the diameter of each of the peripheral ejection holes 72b are such that 50 to 75% of the total amount of gas fuel ejected from the gas burner 7 is ejected from the central ejection hole 72a, and the rest is a plurality of peripheral ejection holes. It is set so as to squirt from 72b.
For example, the diameter of the central ejection hole 72a is set to about 19 mmφ, and the diameter of the peripheral ejection hole 72b is set to about 3 mmφ.
[0031]
The water-cooling holder 73 is formed such that the inner diameter of the distal end portion is smaller than that of the rear end thereof, the small-diameter portion 73a is provided at the distal end portion, and the cylindrical wall of the cylindrical member 73c provided with the large-diameter portion 73b is provided at the rear end. To form a cooling water flow passage 73d, and at the rear end of the cylindrical member 73c, a cooling water inflow pipe 73i and a cooling water outflow pipe 73e are connected to the cooling water flow section 73d. Connected and configured.
Further, a female screw portion is formed on the inner surface of the large inner diameter portion 73b of the water cooling holder 73, and a male screw portion to be screwed to the female screw portion is formed at the tip of the burner main body 71.
[0032]
Then, while the nozzle 72 is fitted inside the large-diameter portion 73b of the water-cooling holder 73, the water-cooling holder 73 is screwed onto the tip of the burner main body 71, so that the nozzle 72 is larger than the small-diameter portion 73a of the water-cooling holder 73. The gas burner 7 is formed integrally with the stepped portion between the inner diameter portion 73b and the tip end surface of the burner main body 71 so as to be sandwiched therebetween.
[0033]
Therefore, the gas fuel is ejected from the central ejection hole 72a of the gas burner 7 in the gas fuel ejection direction Ga (corresponding to the axis Pa of the central ejection hole 72a) in a straight line state, and the 16 surroundings around the central ejection hole 72a are exposed. The gas fuel ejected from the ejection hole 72b flows parallel to the gas fuel ejection direction Ga so as to surround the gas fuel jet ejected from the central ejection hole 72a.
[0034]
Next, the relationship between the center-to-center distance D between the central ejection hole 72a and the peripheral ejection hole 72b and the generation of NOx, the amount of gas fuel ejected from the central ejection hole 72a and the gas fuel ejection from the plurality of peripheral ejection holes 72b. The relationship between the ratio to the amount and the generation of NOx will be described.
The solid line in FIG. 12 shows the result of examining the NOx increase ratio in the gas burner 7 according to the first embodiment by changing the center distance D between the center ejection hole 72a and the peripheral ejection hole 72b. However, the ratio of the ejection amount from the central ejection hole 72a is set in the range of 50 to 75% of the total gas fuel ejection amount from the gas burner 7. In FIG. 12, the increase ratio of NOx is shown as a ratio with respect to the minimum value of the generation amount as 1.
The solid line in FIG. 12 indicates that setting the center-to-center distance D between the central ejection hole 72a and the peripheral ejection hole 72b within the range shown by the above equation 1 is preferable in reducing the amount of NOx generated.
[0035]
FIG. 13 shows the relationship between the ratio of the ejection amount from the central ejection hole 72a to the total ejection amount and the NOx level. However, the distance D between the centers of the central ejection holes 72a and the peripheral ejection holes 72b is set within the range shown by the equation (1). In FIG. 13, the NOx level is shown as a percentage with respect to the maximum value of the generation amount.
FIG. 13 shows that setting the ratio of the ejection amount from the central ejection hole 72a to the total ejection amount to be 50% to 75% is preferable in reducing the generation amount of NOx.
[0036]
As shown in FIG. 3, the furnace wall 4 of the furnace main body 1 is formed with a burner insertion hole 4b for inserting each gas burner 7, and the gas burner 7 configured as described above using the burner insertion hole 4b. Is attached to the furnace wall 4 such that the gas fuel ejection direction Ga becomes the gas fuel ejection angle z set as described above. Further, by filling the heat insulating wool 10 between the periphery of the gas burner 7 and the burner insertion hole 4b, the infiltration of air into the furnace 3 through the outer peripheral portion of the gas burner 7 is blocked to reduce NOx. I'm trying more. The heat insulating wool 10 is made of, for example, glass wool or a ceramic fiber material, and can be appropriately selected and used so as to obtain desired heat resistance and heat insulating properties.
The cooling water supply pipe 11 is connected to the cooling water inflow pipe 73i of the water cooling holder 73, the cooling water discharge path 12 is connected to the cooling water outflow pipe 73e, and the cooling water flows through the cooling water flow section 73d of the water cooling holder 73. The gas burner 7 is cooled by water flow.
[0037]
Accordingly, the supply of combustion air to the gas fuel ejected from the central ejection hole 72a is interrupted by the gas fuel flow ejected from the peripheral ejection hole 72b, so that the combustion is stopped by the gas fuel ejected from the peripheral ejection hole 72b. The auxiliary flame is formed by the gas fuel that advances from around the flow and is ejected from the peripheral ejection holes 72b. Until the combustion starts, the gas fuel ejected from the central ejection hole 72a is heated by the surrounding supplementary flame, and pyrolysis proceeds to generate carbon, and when the combustion starts, a high-luminance main flame is formed. I do. That is, as a whole, so-called slow combustion is performed to form a flame F having a high luminance, thereby increasing the amount of radiant heat and lowering the flame temperature to reduce NOx.
Further, a supplementary flame is formed at the base of the flame F by a plurality of peripheral ejection holes 72b to increase the temperature near the furnace wall 4 where the burner 7 is mounted in the furnace 3 so as to increase the temperature in the front-rear direction (flame F (corresponding to the length direction of F).
[0038]
Next, the results of evaluating the performance of the glass melting furnace configured as described above will be described. In order to compare the performance with the glass melting furnace according to the present invention, the gas atomizing burner 13 is attached to the same furnace body 1 as shown in FIG. Similarly to the above, three fuel injection angles z corresponding to the respective air ports 5 are angles obtained by adding a bottom downward inclination angle x (10 °) and an upper downward inclination angle y (20 °). The one mounted at 15 ° corresponding to one half of 30 ° was used for comparison. FIG. 8A shows a schematic longitudinal side view of a glass melting furnace according to the present invention.
The planar shape of the furnace main body 1 is 5.5 m in the left-right direction and 10.0 m in the front-rear direction, and the tip of the gas burner 7 of the present invention with respect to the upper surface of the molten glass stored in the melting tank 2 and for comparison. The height of each of the tip ends of the gas atomizing burners 13 is 30 cm, and the burning amount per one of the gas burners 7 of the present invention and the gas atomizing burner for comparison is 1750 kW.
[0039]
FIG. 9 shows the relationship between the pulling amount (the amount of melting per day) and the basic unit (the amount of heat required to produce per ton) for each of the glass melting furnace of the present invention and the comparative glass melting furnace. It is a thing.
In the glass melting furnace of the present invention, by appropriately setting the gas fuel ejection angle z of the gas burner 7, the upper surface portion of the molten glass stored in the melting tank 2 and the molten glass are compared with the comparative glass melting furnace. The heating efficiency can be improved while preventing the glass raw material floating on the surface from being washed away, and the basic unit can be reduced by about 4.7% over the entire range of the pulling amount, which can be improved. .
[0040]
The temperature of the molten glass in the melting tank 2 was 1350 ° C., and the temperature of the ceiling of the furnace body 1 at this time was 1505 ° C. in the glass melting furnace of the present invention, whereas the glass melting furnace for comparison was In the glass melting furnace of the present invention, the temperature of the ceiling of the furnace main body 1 can be lowered as compared with the glass melting furnace for comparison, so that the durability can be improved.
[0041]
NOx concentration of exhaust gas (O ₂ = 0%) was 800 ppm in the glass melting furnace of the present invention, whereas it was 1100 ppm in the comparative glass melting furnace. In the glass melting furnace of the present invention, compared to the comparative glass melting furnace. , NOx concentration can be reduced by about 27%.
[0042]
Therefore, by applying the present invention to an end port type glass melting furnace, it is possible to prevent the upper surface portion of the molten glass stored in the melting tank 2 and the glass raw material floating in the molten glass from being washed away. The effect of improving the heating efficiency and improving the durability by lowering the temperature of the ceiling of the furnace main body 1 is remarkable.
[0043]
[Second embodiment]
Hereinafter, a second embodiment in which the present invention is applied to a glass melting furnace will be described with reference to FIGS. 11A is a view in the gas fuel ejection direction Ga at the nozzle 72, and FIG. 11B is a cross-sectional view in the gas fuel ejection direction Ga at the nozzle 72.
In the second embodiment, the gas burner 7 is configured as follows, different from the first embodiment, and the other configuration is the same as that of the first embodiment.
[0044]
The gas fuel ejection direction of the plurality of peripheral ejection holes 72b in the gas burner 7 is defined by the gas fuel ejection direction Ga of the central ejection hole 72a in the circumferential direction of the central ejection hole 72a with respect to the radial direction of the central ejection hole 72a. In a direction inclined in the same direction and in a direction intersecting with the gas fuel ejection direction Ga of the central ejection hole 72a, a forward divergent portion inclined outwardly with respect to the gas fuel ejection direction Ga of the central ejection hole 72a. And the distance between the opening edge of the central ejection hole 72a and the opening edge of the peripheral ejection hole 72b is 0.5 times or more the diameter of the peripheral ejection hole. It is configured such that 50 to 75% of the total gas fuel ejection amount is ejected from the central ejection hole 72a, and the remainder is ejected from a plurality of peripheral ejection holes 72b.
[0045]
The gas burner 7 will be described.
The central ejection hole 72a of the nozzle 72 is formed in a single columnar material, in a circular shape in which the axis Pa is coaxial with the columnar material, and six peripheral ejection holes 72b are formed with the same diameter. Each of the shaft cores Pb is formed in a circular shape inclined from the base end to the tip in the same direction in the circumferential direction of the central ejection hole 72a and inclined outward in the radial direction of the central ejection hole 72a. is there. That is, the gas fuel ejection direction of each of the six peripheral ejection holes 72b is defined by the gas fuel ejection direction Ga of the central ejection hole 72a and the circumferential direction of the central ejection hole 72a with respect to the radial direction of the central ejection hole 72a. In a direction inclined in the same direction and in a direction perpendicular to the gas fuel ejection direction Ga of the central ejection hole 72a, a forward divergent portion inclined outwardly with respect to the gas fuel ejection direction Ga of the central ejection hole 72a. It is configured to be in the direction. The gas fuel ejection direction Ga of the central ejection hole 72a is the gas fuel ejection direction of the gas burner 7 as a whole.
Then, similarly to the first embodiment, the gas burner 7 is configured by integrally assembling the burner main body 71, the nozzle 72, and the water-cooling holder 73.
[0046]
The gas burner 7 configured as described above is attached to the furnace wall 4 such that the gas fuel ejection direction Ga becomes the gas fuel ejection angle z set as described above, as in the first embodiment.
[0047]
In the gas burner 7 of the second embodiment, the gas fuel is swirled from the plurality of peripheral ejection holes 72b in the gas fuel ejection direction Ga of the central ejection hole 72a and the gas fuel ejection direction of the central ejection hole 72a. When viewed in a direction perpendicular to Ga, the gas is ejected in a pre-expanded shape.
Accordingly, the effect of shutting off the combustion air with respect to the gas fuel ejected from the central ejection hole 72a is increased, and the gas fuel ejected from the plurality of peripheral ejection holes 72b is separated from the gas fuel ejected from the central ejection hole 72a. Since the condition is improved, slow combustion is further promoted, and a flame F having higher luminance is formed.
[0048]
In FIG. 12, the broken line and the solid line on the side where the center-to-center distance D is smaller than the intersection of the broken line and the solid line are the centers of the central ejection hole 72 a and the peripheral ejection hole 72 b in the gas burner 7 according to the second embodiment. The result of having investigated the NOx increase ratio by changing the distance D is shown. However, the ratio of the ejection amount from the central ejection hole 72a is set in the range of 50 to 75% of the total gas fuel ejection amount from the gas burner 7. The NOx increase ratio is shown as a ratio with respect to the minimum value when the gas burner 7 of the first embodiment is examined with the minimum value being 1.
According to FIG. 12, the distance D between the centers of the central ejection holes 72a and the peripheral ejection holes 72b is set to “(1/2) × (d _a + D _b ) + (1/2) × d _b In other words, if the interval between the opening edge of the central ejection hole 72a and the opening edge of the peripheral ejection hole 72b is set to be 0.5 times or more the diameter of the peripheral ejection hole, NOx is generated. It can be seen that it is preferable in reducing the amount.
The relationship between the ratio of the ejection amount from the central ejection hole 72a to the total ejection amount and the NOx level is the same as that in the first embodiment shown in FIG. It is preferable to set the ratio of the ejection amount to 50 to 75% in order to reduce the generation amount of NOx.
[0049]
Incidentally, the angle α at which the axis Pb of the peripheral ejection hole 72b is inclined in the circumferential direction of the central ejection hole 72a from the base end to the distal end is set, for example, in a range of 0 <α ≦ 40 °. The angle β inclined outward in the radial direction of the hole 72a is preferably set, for example, in the range of 0 <β ≦ 60 ° in order to form a flame F having a high luminance and an appropriate flame length.
[0050]
As for the glass melting furnace according to the second embodiment, similarly to the above-described first embodiment, as a result of comparing the performance with the glass melting furnace for comparison, the unit consumption was improved, the temperature of the ceiling was lowered, and the NOx concentration was increased. In all aspects of the reduction in the results, the same results as in the first embodiment were obtained.
[0051]
[Another embodiment]
Next, another embodiment will be described.
(B) In the above embodiment, the case where the present invention is applied to an end-port type glass melting furnace is described. However, for example, the present invention may be applied to a so-called side-port type glass melting furnace. it can.
As shown in FIG. 14, the side port type glass melting furnace has a charging port 4 i on a furnace wall 4 on one side edge of a rectangular melting tank 2 in a plan view, and a furnace wall 4 opposed to the furnace wall 4. An outlet hole 4e is provided, a plurality of air ports 5 are arranged in parallel on each of the right and left furnace walls 4 from the inlet port 4i toward the outlet hole 4e, and an air supply path 6 is provided corresponding to each air port 5. Two gas burners 7 are provided below each air port 5, and a heat storage chamber 8 is provided on each of the left and right sides of the furnace main body 1 so as to communicate with a plurality of air supply passages 6 on each side. It is.
Then, the gas burners 7 on the left and right sides are alternately burned at regular intervals to perform alternating combustion, and the glass material is introduced into the melting tank 2 from the inlet 4i, and the glass material is taken out while being melted. It is configured to flow down toward the hole 4e and to guide clean molten glass to the work tank 9 through the extraction hole 4e.
Also in this side port type glass melting furnace, similarly to the above embodiment, the bottom downward inclination angle x and the upper downward inclination angle y of the air supply passage 6 are such that the bottom downward inclination angle x <the upper downward inclination angle y. Under the conditions, the bottom downward inclination angle x is set in a range of 10 ° ≦ x ≦ 20 °, and the upper downward inclination angle y is set in a range of 20 ° ≦ y ≦ 25 °. Further, in relation to the bottom downward inclination angle x of the air supply passage 6, the gas fuel ejection angle z of the gas burner 7 is limited to an angle obtained by adding the bottom downward inclination angle x above the horizontal direction, and Set the angle within the angle range with the direction as the lower limit.
[0052]
(B) Under the condition that the bottom downward inclination angle x <the upper downward inclination angle y, the bottom downward inclination angle x is out of the range of 10 ° ≦ x ≦ 20 °, and the upper downward inclination angle y is 20 ° ≦ y ≦ 25 °. May be set outside of the range.
[0053]
(C) The bottom downward inclination angle x and the upper downward inclination angle y of the air supply passage 6 may be set so as to satisfy the relationship of the bottom downward inclination angle x ≧ the upper downward inclination angle y, but the combustion air is directed upward. In order to prevent the surface from rising up, it is preferable to set the relationship in such a way that the bottom downward inclination angle x <the top downward inclination angle y.
[0054]
(D) The gas fuel ejection angle z of the gas burner 7 is not limited to 8 ° exemplified in the above-described embodiment, and is, in relation to the bottom downward inclination angle x of the air supply passage 6, relative to the horizontal direction. The angle can be appropriately changed within an angle range in which the upper limit is the angle obtained by adding the bottom downward inclination angle x and the lower limit is the horizontal direction.
That is, the gas fuel jetting direction of the gas burner 7 may be horizontal. Alternatively, the gas fuel ejection direction of the gas burner 7 can be appropriately set on the condition that the angle of the upward inclination with respect to the horizontal direction is equal to or less than the bottom downward inclination angle x.
[0055]
(E) The height of the nozzle at the tip of the gas burner 7 with respect to the upper surface of the molten glass stored in the melting tank 2 is not limited to 30 cm illustrated in the above embodiment, and may be lower than 30 cm. Alternatively, it may be higher than 30 cm. However, when it is set lower than 30 cm, it is preferable to set the gas fuel ejection angle z of the gas burner 7 to a large value in order to prevent the glass raw material floating in the melting tank 2 from being washed away, and set it higher than 30 cm. In this case, it is preferable to set the gas fuel injection angle z of the gas burner 7 to a small value in order to suppress a decrease in the heating efficiency.
(F) The number of gas burners 7 installed in one air supply path 6 is not limited to three illustrated in the above embodiment, but can be changed as appropriate, and one, two, or Or more than four.
[0056]
(G) The shape of the air supply passage 6 is not limited to the rectangular tube shape having a rectangular cross-sectional shape of the flow channel as exemplified in the above embodiment. For example, the shape may be a cylindrical shape, or a shape in which the upper portion has an arch shape and the bottom portion has a flat shape.
[0057]
(H) The specific configuration of the gas burner 7 is not limited to the configuration exemplified in the above-described first and second embodiments. For example, a configuration in which one ejection hole is provided, or a configuration in which a plurality of ejection holes are dispersed and arranged without distinguishing between the center and the periphery may be used.
[0058]
(I) As the oxygen-containing gas supplied to the combustion area of the gaseous fuel ejected from the gas burner 7 by the air supply path 6, in addition to air, pure oxygen gas, oxygen-enriched air having a high oxygen content, or the like may be used. . Further, the combustion exhaust gas of the gas burner 7 may be supplied as the oxygen-containing gas together with the air.
[0059]
(V) The present invention can be applied to various melting furnaces other than the glass melting furnace exemplified in the above embodiment and the glass melting furnace exemplified in another embodiment shown in FIG.
For example, in addition to the type in which the gas burner 7 is alternately burned, the present invention can be applied to a continuous combustion type.
Further, the present invention is not limited to a melting furnace for melting glass, but may be applied to a melting furnace for melting raw materials other than glass.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional side view of a glass melting furnace according to an embodiment.
FIG. 2 is a view taken in the direction of an arrow II in FIG. 1;
FIG. 3 is a longitudinal sectional side view of a main part of the glass melting furnace according to the embodiment.
FIG. 4 is a cross-sectional view of a main part of the gas burner according to the first embodiment, taken along a gas fuel ejection direction.
FIG. 5 is a view of a main part of the gas burner according to the first embodiment as viewed in a gas fuel ejection direction.
FIG. 6 is a view of a nozzle of the gas burner according to the first embodiment.
FIG. 7 is an exploded perspective view of the gas burner according to the first embodiment.
FIG. 8 is a schematic longitudinal side view of each of a glass melting furnace and a comparative glass melting furnace according to the embodiment.
FIG. 9 is a diagram showing a relationship between a lifting amount and a basic unit.
FIG. 10 is a sectional view of a main part of a gas burner according to a second embodiment, taken along a gas fuel ejection direction.
FIG. 11 is a view of a nozzle of a gas burner according to a second embodiment.
FIG. 12 is a diagram showing the relationship between the center-to-center distance between the central ejection hole and the peripheral ejection holes of the gas burner and the NOx level.
FIG. 13 is a diagram showing the relationship between the ratio of the ejection amount from the central ejection hole to the total ejection amount and the NOx level.
FIG. 14 is a cross-sectional plan view of a glass melting furnace according to another embodiment.
[Explanation of symbols]
2 Dissolution tank
3 Upper space
5 Oxygen-containing gas supply port
6 Oxygen-containing gas supply path
7 Fuel injection section
72a Central vent
72b Aperture orifice
x Bottom downward inclination angle
z Gas fuel ejection angle

Claims (2)

A fuel ejection unit for ejecting gaseous fuel into a space above a region where the melt exists in the melt tank;
An oxygen-containing gas supply path for supplying the oxygen-containing gas obliquely downward is provided through a oxygen-containing gas supply port located above the fuel ejection portion and to a combustion region of the gas fuel ejected from the fuel ejection portion. Melting furnace,
The gas fuel ejection angle of the fuel ejection portion is related to a bottom downward inclination angle at which the bottom of the oxygen-containing gas supply path is inclined downward with respect to the horizontal direction, and the bottom downward inclination angle is upward with respect to the horizontal direction. The melting furnace is configured to be set within an angle range in which an angle obtained by adding is an upper limit and a horizontal direction is a lower limit. The fuel outlet is configured to include a central outlet and a plurality of peripheral outlets around the central outlet.
The gas fuel ejection direction of each of the plurality of peripheral ejection holes is configured to be parallel or substantially parallel to the gas fuel ejection direction of the central ejection hole,
The distance between the opening edge of the central ejection hole and the opening edge of the peripheral ejection hole is 0.5 times or more the diameter of the peripheral ejection hole, and the diameter of the central ejection hole and the diameter of the peripheral ejection hole are added. It is configured to be 1.5 times or less of the value,
2. The fuel cell according to claim 1, wherein 50 to 75% of the total amount of gas fuel ejected from the fuel ejection unit is ejected from the central ejection hole, and the remainder is ejected from the plurality of peripheral ejection holes. 3. melting furnace.

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