JP3155155B2 - Single-ended radiant tube heating element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant tube heating element in which high-temperature air and fuel are reacted inside a single-ended tube whose one end is closed, for example, for heating a melting furnace, a holding furnace, an atmosphere heating furnace and the like. Used for equipment.

[0002]

2. Description of the Related Art As a heat source of a single-end type radiant tube heating element, an electric heater is generally used, but a gas fuel is also used (for example, Japanese Utility Model Laid-Open Publication No. 64-5765). One of the characteristics that the single-end type radiant tube should have is that the tube bottom is heated or evenly heated to the tube bottom in order to increase the efficiency of heat transfer to the molten material to be heated. In a conventional gas-fired single-end radiant tube, a gas nozzle is extended to the vicinity of the tube bottom in order to heat the tube bottom, and a flow zone of a combustion flow and an exhaust flow is divided using an inner tube. However, the inner tube is constantly exposed to high temperatures and is severely deteriorated, so that maintenance such as replacement has been a problem. In order to solve this, one of the present applicants has proposed a single-ended radiant tube heating element composed of a disk rotary combustion burner main body and a long single-ended tube (filing date: December 1993). March 3). The burner tile of the single-end type radiant tube heating element is a flat plate. To prevent a short path to the fuel exhaust hole, an air nozzle (a vent hole in the burner tile used for supply and exhaust) and a gas nozzle (burner tile) The distance between the fuel injection hole and the center of the tile was increased. As a result, the force accompanying the fuel flow of the supply air is reduced. Therefore, it has been dealt with by increasing the momentum of the combustion air to improve the fuel accompanying capacity.

[0003]

However, the increase of the momentum of the combustion air has caused the following two major problems. One is an increase in the leak inside the burner (leakage of the air supply from the air supply passage to the exhaust passage) due to an increase in the pressure in the air supply passage inside the burner to improve the flow velocity of the combustion air. , A decrease in fuel accompanying force, an increase in the amount of short path to fuel exhaust, incomplete combustion due to insufficient air, and an increase in CO in exhaust. The other is oxidation of the tube due to an increase in the air ratio that increases the amount of air leaked from the burner, generation of turbulence at the bottom of the tube, reduction of heat exchange temperature efficiency (reduction of radiation coefficient), reduction of heat transfer efficiency to the object to be heated ,
The resulting worse fuel economy. SUMMARY OF THE INVENTION An object of the present invention is to provide a gas-fired single-ended radiant tube capable of heating the tube bottom without increasing the momentum of combustion air, increasing the leak inside the burner, and increasing the air ratio as compared with the conventional case. An object is to provide a heating element.

[0004]

The heat storage combustion burner of the present invention which achieves the above object is as follows. (1) A heat storage combustion burner and a single end tube having one end closed. The heat storage combustion burner is arranged on one side of the heat storage body in the axial direction of the heat storage body. An air supply / exhaust surface having pores, a burner tile having a fuel release surface, and a rotating disk and a fixed disk disposed on the other axial side of the heat storage body and slidably in surface contact with each other. A single-ended radiant tube heating element, comprising: a switching mechanism. (2) It consists of a heat storage combustion burner and a single-ended tube whose one end is closed. The heat storage combustion burner is arranged on one side of the heat storage body in the axial direction of the heat storage body. A burner tile having a plurality of open / closed air supply / exhaust surfaces, a protruding portion protruding from the air supply / exhaust surface, and a fuel release surface formed inside the protruding portion; and provided on the other axial side of the heat storage body. A single-ended radiant tube heating element comprising: a supply / exhaust switching mechanism; (3) The single-ended radiant tube heating element according to (1) or (2), wherein the burner tile and the heat storage part of the heat storage combustion burner are built in the single end tube. (4) The single-ended radiant tube heating element according to (1), wherein the rotating disk is rotated only in one direction. (5) The single-ended radiant tube heating element according to (1), wherein the rotating disk is reciprocally rotated. (6) The single-ended radiant tube heating element according to (2), wherein the fuel release surface is formed so as to expand toward the tip of the protruding portion. (7) The single-ended radiant tube heating element according to (2), wherein an air guide extending in the axial direction is formed on an outer peripheral surface of the protrusion. (8) The single-ended radiant tube heating element according to (2), wherein an air nozzle separator protruding in a protruding direction of the protruding portion at a position between the ventilation holes is provided on the air supply / exhaust surface. (9) The single-ended radiant tube heating element according to (1) or (2), wherein a leak detection mechanism extending toward the bottom of the single-ended tube is provided in the single-ended tube. (10) The single-ended radiant tube heating element according to (1) or (2), wherein the single-ended tube has an inner tubeless structure having no inner tube.

[0005]

In the single-end type radiant tube heating element of the above (1), since the switching mechanism is composed of a double disk consisting of a rotating disk and a fixed disk, the sliding contact area becomes large, and air supply is performed between the disks. Leakage to the exhaust gas is reduced, and the supply pressure can be increased. Accordingly, the flow velocity of the combustion air is increased accordingly, the flame reaches far, and the single end tube can be heated to the bottom of the tube. Along with the increase in the flow velocity of the combustion air, the force of the combustion air accompanying the fuel increases, and the fuel is prevented from being short-passed as it is to the exhaust and discharged in an incomplete combustion state, and the CO in the exhaust gas is reduced. I do. Also, by increasing the combustion air flow rate, part of the exhaust gas is recirculated caught in the air supply, in addition to reducing the NO _X becomes slow combustion, it will be heated uniformly over the tube length. Further, since the flame changes its position in the circumferential direction in the single end tube in accordance with the switching of the supply and discharge by the switching mechanism, the heating of the single end tube is made uniform in the circumferential direction, and the life of the single end tube is extended. In the single-end type radiant tube heating element of the above (2), the fuel release surface protrudes from the supply / exhaust surface in the burner tile, so that fuel is suppressed from being caught in the exhaust gas, and the fuel release surface and the supply / discharge are switched. The space in the direction perpendicular to the axial direction with respect to the vent hole to be provided may be reduced, and the fuel entrainment of the combustion air is increased, so that the bottom of the tube can be heated. In addition, entrainment of fuel into the exhaust gas and a short path are suppressed, so that CO,
HC is reduced. In the above (3), in the burner main body,
Since the high-temperature parts such as the burner tile and the heat storage element are incorporated in the single-ended tube, the heat loss to be dissipated is prevented, and the amount of heat transferred to the tube is increased. In addition, the distance between the burner tile portion and the tube bottom is reduced, which is effective in raising the temperature of the tube bottom. In the above (4), the rotating disk is rotated in one direction by a motor drive or the like, and the heat storage body is rotated in the circumferential direction in the air supply portion and the exhaust portion so that the entire area is reliably used. In the above (5), the rotating disk is reciprocated and driven by a cylinder or the like. Switching between supply and discharge is faster than one-way rotation, and constitutes an instantaneous switching shutter. In the above (6), since the fuel release surface has a divergent shape, the entrainment of the fuel with the combustion air is improved, and the short path to the exhaust is reduced. Therefore, the CO concentration is reduced. Also, unlike the case of the flat flame holding surface, the minute vortex generated along the flame holding surface is prevented from being drawn by the exhaust by the fuel release surface and burns almost completely in the fuel release surface. The concentration is further reduced. In the above (7), since the air guide groove is formed on the side surface of the protruding portion, the flow of the combustion air is restricted by the guide, and the directional air is discharged. This facilitates heating to the bottom of the tube. Further, the directivity and the accompanying property of the fuel to the combustion air having the increased speed are enhanced, and the short path of the fuel to the exhaust gas is suppressed, so that the CO in the exhaust gas is reduced. Further, to the combustion air flowing through the guide, the entrainment of the exhaust gas from the outside, the oxygen lean combustion air is created, whereby the combustion of the mixture of fuel and combustion gas becomes slow, others NO _X is reduced , The single-ended tube is evenly heated further. Accordingly, the reaction region moves toward the tube bottom, and the tube bottom can be heated. In the above (8), since the air nozzle separator protrudes between the air holes on the air supply / exhaust surface of the burner tile, a short path of the combustion air from the air hole serving as the air supply hole to the air hole serving as the exhaust hole is provided. Can be blocked. When a short path occurs, air shortage occurs and incomplete combustion occurs, but this can be suppressed by the air nozzle separator. In the above (9), since the leak detection mechanism is provided,
If the single-ended tube is damaged and the molten metal enters the single-ended tube, the leak detection mechanism
It can be detected immediately and necessary measures can be taken. In the above (10), since the inner tube is not provided, there is no thermal damage to the inner tube, and the life is extended.

[0006]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 13 are applicable to any embodiment of the present invention, and FIGS. 2 to 5, 8 and 9 relate to the first embodiment of the present invention, and FIGS. 6 relates to a second embodiment of the present invention, FIG. 6 relates to a third embodiment of the present invention, FIG. 7 relates to a fourth embodiment of the present invention, and FIG.
Relates to a fifth embodiment of the present invention. Components common to all the embodiments are denoted by the same reference numerals throughout the embodiments.

First, the components common to all the embodiments of the present invention and the operation thereof will be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIG.
A single-end radiant tube heating element 10 for heating an object to be heated (for example, molten aluminum) 102 in the furnace is provided in a furnace 101 such as a melting furnace, an insulated furnace, or an atmosphere heating furnace.
0 is provided so as to pass through the furnace wall. As shown in FIG. 1, the single-end type radiant tube heating element 100 includes a heat storage combustion burner (burner body) 1 and a material having excellent acid resistance, erosion resistance, and heat resistance (for example, ceramics, but may be metal). ) And a single-ended tube 103 whose one end is closed. The single end tube 103 is heated by the secondary injection and convection by the flame generated by the combustion of the fuel and the combustion air injected from the heat storage combustion burner 1, and the combustion exhaust gas is exhausted through the heat storage combustion burner 1. Single end tube 1
In reference numeral 03, at least the bottom portion 104 is immersed in the molten metal 102 and heats the molten metal 102 by convection and heat conduction of the molten metal. In order for the single-ended tube 103 to effectively heat the molten metal to the lower part, the single-ended tube 103 needs to be heated to the bottom 104.

As shown in FIG. 1 and FIG. 2, a heat storage combustion burner 1 has a heat storage body 30 divided into a plurality of parts by a partition 21.
And a vent hole 27 arranged on one side in the axial direction of the heat storage body 30 to allow the fuel injection nozzle 20 to pass therethrough and to switch between supply and discharge.
, A switching mechanism 40 disposed on the other side in the axial direction of the heat storage body 30, and a frame 10 in which the fuel injection nozzle 20, the heat storage body 30, and the switching mechanism 40 are assembled. . The switching mechanism 40 includes a rotating disk 44 and a fixed disk 46 that are slidably contacted with each other.
The rotating disk 44 has a plurality of ventilation openings 42 and 43 which are connected and blocked by the rotation of the rotating disk 44, and the fixed disk 46 has a through hole 47. The openings 42, 43 include an air supply ventilation opening 42 communicating with one side of the partition wall 41 and an exhaust ventilation opening 43 communicating with the other side of the partition wall 41.

The heat storage combustion burner 1 is connected to a blowing means (for example, a blower, a compressor, etc.) 4 via an air supply passage 2 and is opened to the atmosphere via an exhaust passage 3. On the other hand, the fuel and pilot air from the fuel injection nozzle 20 and the air supply flowing through the heat storage body 30 from the air supply ventilation opening 42 are supplied to the single end tube 10.
It is sent into 3. The switching mechanism 40 controls the flow of the supply air and the exhaust air to the heat storage body divided portion at predetermined time intervals (for example,
(Every 20 seconds to several minutes). The air supply is, for example, about 20 ° C. on the upstream side of the heat storage body 30, is heated when passing through the heat storage body 30, and becomes, for example, about 900 ° C. when flowing out as combustion air from the air injection nozzle 26, The temperature of the heat storage body is, for example, about 1000 ° C. when entering the heat storage body 30 as an exhaust gas flow, and the temperature of the heat storage body is lowered to, for example, about 200 ° C. when passing through the heat storage body 30. Next, the switching mechanism 40 switches between the supply and the exhaust, and supplies the air to the place where the exhaust has been flowing, and the exhaust to the place where the supply has been flowing. Thus, the heat of the exhaust gas is stored in the heat storage body 30, and when switched to the supply air, the supply air is warmed by the stored heat.

FIG. 2 is an enlarged view showing an example of the burner 1 for heat storage combustion. The fuel injection nozzle 20 extends in the axial direction at the center of the burner, and a primary air (pilot air) pipe 21 extends coaxially therewith. The outer peripheral surface of the fuel injection nozzle 20 and the inner peripheral surface of the primary air pipe 21 The primary air flows through the annular passage between the two. Fuel injection nozzle 2
0 is provided with a pilot fuel discharge port 20a which is covered with an electrical insulating material, for example, an insulator except for the tip portion, and which discharges part of the fuel as pilot fuel at the tip portion which is not covered with the electrical insulating material; The pilot fuel discharged therefrom is electrically sparked between the tip of the fuel injection nozzle not covered with the electric insulating material and the primary air pipe 21 to ignite.

FIGS. 3 and 4 show the detailed structure of the burner tile 22. FIG. The burner tile 22 has a supply / exhaust surface 23 in which a plurality of ventilation holes 26 for switching supply / discharge are opened.
And a protrusion 24 protruding from the supply / exhaust surface 23, and a fuel release surface 25 formed from the inside to the tip of the protrusion 24 for releasing the fuel / primary air mixture. The ventilation hole 26 functions as an air supply hole at one time and functions as an exhaust hole at some time, and the supply and exhaust are switched. Switching between supply and discharge is performed by a switching mechanism 40 described later. Air supply / exhaust surface 23 of burner tile 22
An air nozzle separator 29 is provided between the vent holes 26 so as to protrude therefrom, to prevent the combustion air ejected from the air supply holes from flowing to the exhaust holes, and to allow all the combustion air to contribute to the combustion. is there. The fuel release surface 25 is formed so as to expand toward the tip of the protrusion 24. The flared structure may be tapered or R-shaped, and the tapered surface and the R-surface may be smooth surfaces or may be jagged (increase the contact area). For)
It may be a surface.

A guide groove 27 extending in the axial direction is formed concentrically with the ventilation hole 26 on the outer peripheral side of the protrusion 24. Ventilation hole 2 serving as air supply hole among ventilation holes 26
Supply air flowing out through 6 (secondary air, main air)
Is a flow 28A having a high directivity and at least partly passing through the guide groove 27 and having a high flow velocity. The ventilation holes 26 are narrowed more smoothly as they approach the air supply / exhaust surface 23.
When the supply air passing through the air passage 26 passes through the ventilation hole 26, the flow velocity is increased. Further, the ventilation hole 26 is provided in the air supply / exhaust surface 2.
3, the center of the passage is closer to the axis of the protruding portion 24. The ventilation hole 26 is provided in the air supply / exhaust surface 23 at the ventilation hole 2
It is desirable that at least a part of the cross section of the projection 6 overlaps with the projection 24, and the guide groove 2 is formed on the side of the projection of the overlapping portion.
7 are formed. Therefore, the ventilation hole 26 is not closed by the protrusion 24. However, the ventilation holes 26 may be provided so that the cross section of the ventilation holes 26 on the air supply / exhaust surface 23 is in contact with the outer periphery of the protruding portion 24.

The heat storage body 30 is made of a honeycomb-shaped ceramic, and has a large contact area with a gas by being formed in a honeycomb shape. The heat storage body 30 is divided into a plurality in the circumferential direction by a partition wall 31.

FIGS. 8 and 9 show the details of the switching mechanism 40 side. Some members of the switching mechanism 40 are movable members. For example, in the example of FIG. 8, the partition wall 41 and the rotating disk 44 are movable members. The movable member of the switching mechanism 40 is driven in one direction or reciprocating rotation by a driving means (for example, a motor, a cylinder, etc.) 45. Switching mechanism 40
The remaining members are stationary members. For example, the fixed disk 46 is a stationary member. Since the rotating disk 44 and the fixed disk 46 are in surface contact with each other, the contact area is large and the sealing property is large as compared with the conventional contact between the partition wall and the rotating disk. The partition wall 41 of the switching mechanism 40 extends in the circumferential direction, and forms the air supply passage 2 on one of the inner and outer circumferences and the exhaust passage 3 on the other. One of the inner and outer peripheries of the partition wall 41 of the rotating disk 44 is provided with an air supply ventilation opening 4.
2 are opened, and the other side is provided with an exhaust ventilation opening 43. The air supply opening 42 is provided on the air supply passage 2 side, and the exhaust air opening 43 is provided on the exhaust passage 3 side. The rotating disk 44 is fixed to the fixed disk 4 by a spring 51.
6 (see FIG. 10). When the rotating disk 44 is rotated, the supply and exhaust flows of the divided portions of the heat storage body 30 are switched.

Supply and exhaust ventilation is performed so that the volume of the portion covered by the exhaust ventilation opening 43 among the plurality of divided heat storage portions is equal to or greater than the volume of the portion covered by the air supply ventilation opening 42. The number and shape of the openings 42 and 43 are set. For example, when the heat storage body 30 is divided into four by the partition wall 31, three or two are covered by the exhaust ventilation opening 43, and one is covered by the air supply ventilation opening 42. Or two. Since the exhaust velocity is reduced by increasing the exhaust volume, the heat storage body 3
0 easily stores heat. When the drive means 45 is formed of a motor, the drive means 45 is provided closer to the air supply passage 2 than the partition wall 41 so that the motor is not affected by the heat of the exhaust gas. Furthermore, in the burner 1 for heat storage and combustion, the part of the burner tile 22 and the heat storage 30 is a single-end tube 1.
03.

The operation of the above common configuration is as follows. First, in the switching mechanism 40, since the rotating disk 44 and the fixed disk 46 are slidably in surface contact with each other, the contact area between the rotating disk 44 and the fixed disk 46 increases, and the air supply is fixed to the rotating disk 44. Leakage to the exhaust through the space between the disk 46 can be suppressed. By increasing the sealing performance, the pressure of air supply can be increased.
Due to the increase of the supply pressure, the outflow velocity of the combustion air increases, and the flame flows through the single end tube 103 at the bottom 10.
4 to effectively heat the bottom 104. In addition, by increasing the supply pressure, the fuel injection side can increase the continuity of the fuel flow with the combustion air flow on the fuel injection side, thereby suppressing a short path of the fuel to the exhaust hole and reducing CO. Also, by increasing the outflow speed of combustion air,
Inclusion of flue gas into the combustion air increases, thereby slowing down combustion and reducing NOx. Also,
Since the fixed disk is provided, the degree of freedom of the air supply cover area is improved as compared with the case where the rotating disk 44 passes through the partition wall, and a setting that does not cause a decrease in the air supply amount at the time of switching becomes possible. Since the thickness of the partition wall 31 can be freely set, the design of the heat storage chamber is free.

Further, since the burner tile 22, the heat storage body 30, and the switching mechanism 40 are assembled inside the frame 10, piping for connecting the heat storage body 30 and the switching mechanism 40 is not required, and the piping is constructed. Is unnecessary, and the apparatus is downsized.
Further, when there is a pipe, it is necessary to purge exhaust gas in the pipe at the time of switching, but since there is no pipe, purging is not required, and the switching time is short. Although the heat storage body 30 is divided in the circumferential direction by the partition 31, a switching structure that easily switches the supply and exhaust of each part of the heat storage body 30 by rotating the rotary disk 44 is obtained. Further, since the partition wall 41 of the switching mechanism 40 is extended in the circumferential direction, even when the rotary disk 44 is rotated, the movable supply passage opening 42 and the stationary intake passage 2 always correspond to each other, and the movable exhaust ventilation is provided. Opening 43
And the stationary exhaust passage 3 can correspond to each other. Also, since the drive motor 45 is installed in the air supply passage 2,
The influence of the heat of the exhaust gas on the drive motor 45 is suppressed. Further, since the exhaust volume is equal to or more than the supply air volume, the exhaust flow velocity is reduced, and the heat storage body 30 can easily store heat.

Further, since the protruding portion 24 protrudes from the air supply / exhaust surface 23 and the fuel opening surface 25 is formed inside the protruding portion 24, the fuel opening surface 25 and the vent hole 26 serving as the exhaust hole among the vent holes 26. And the flow 28B of the mixture of the fuel and the primary air exiting from the fuel release surface 25 is less likely to be caught in the exhaust flow 28C flowing to the exhaust hole. For this reason,
The distance between the fuel opening surface 25 and the vent hole 26 in the direction perpendicular to the axial direction may be reduced, so that the fuel entrainment of the combustion air is increased, and the tube bottom 104 can be heated. In addition, a short path to the exhaust of the fuel is suppressed by increasing the fuel entrainment of the combustion air. When the fuel is entrained in the exhaust, the fuel incompletely burns and generates CO because the amount of oxygen in the exhaust is small, but in the present embodiment, the entrainment of the fuel into the exhaust is suppressed, so that the CO is significantly reduced. Become. In addition, since the fuel release surface 25 is flared toward the tip of the protruding portion, while the fuel and the primary air flow inside the fuel release surface 25, the fuel and the primary air are drawn from the exhaust flow 28C to the exhaust hole side. Even if this is done, the fuel release surface 25 becomes a hindrance and the entrainment into the exhaust flow 28C is suppressed. In addition, since the fuel opening surface 25 has a flared shape, the entrainment of the fuel into the air supply flow 28A is enhanced, and the fuel is mixed with the air supply and easily burned completely. This further reduces the production of CO. Projection 2
4 and the divergent structure of the fuel release surface 25, CO that was about 3000 ppm in the exhaust gas in the conventional structure was reduced to about 20 ppm.
It is reduced to 0 ppm or less.

The air guide groove 2 is formed on the side of the protrusion 24.
Since the air supply 7 is formed, at least a part of the supply air flowing out from the ventilation hole 26 enters the air guide groove 27. The air supplied into the air guide groove 27 flows linearly in the air guide groove 27, and flows out from the tip of the protruding portion forward with directivity. This flow is a high-velocity flow, in which the flow velocity cannot be controlled because there is almost no diffusion while flowing through the air guide groove 27. Thereby, the bottom 104 of the single-ended tube 103 is heated. Further, the force of attracting and entraining the fuel in this flow is large. This entrainment further reduces fuel entrainment in the exhaust, reducing the above-mentioned about 200 ppm or less of CO to about 100 ppm or less. Even if the fuel mixes with the supply air having high directivity and high flow velocity, the mixing of the fuel and the air supply is not instantaneously promoted,
As the flow of supply air moves downstream, it gradually mixes and burns slowly, and complete combustion in the process. Further, since the flow flowing through the guide groove 27 involves exhaust gas from the outside, the combustion becomes slow even due to lack of oxygen. Due to this slow combustion, the bond between N ₂ and O ₂ also becomes slow, and NO
_X generation is also greatly reduced. Furthermore, the flame extends to the tube bottom 104 due to the high flow rate and slow combustion, so that the single-end tube 103 is entirely heated, and more uniform heating becomes possible.

Further, since the air hole 26 is narrowed as it approaches the air supply / exhaust surface 23, the flow velocity of the air supply is increased when the air supply passes through the air hole 26. This further enhances the effect of the above-described large air supply flow rate. Further, since the center of the ventilation hole 26 is shifted toward the axis of the protruding portion, a considerable portion enters the guide groove 27 when the supply air exits from the ventilation hole 26. Then, the above-described directional air supply flow is generated more strongly. Further, in order to further enhance the reactivity, the axis of the vent hole 26 may be slightly inward (10 to 20 degrees) inward (the direction in which air supply approaches the axis of the protruding portion) as necessary.

Further, of the heat storage combustion burner 1, a part of the heat storage body 30 and the burner tile 22 (a part where the temperature becomes high).
Is contained in the ceramic single-ended tube 103, so that heat dissipation is suppressed, and it is useful to heat the single-ended tube 103 to the bottom 104.
Further, due to the flow of the combustion air having the directivity, the combustion air and the exhaust gas can be separated in the single-end tube 103 without the inner tube, so that the inner tubeless structure can be adopted.

Next, a configuration specific to each embodiment of the present invention,
The operation will be described. In the first embodiment of the present invention, FIG.
As shown in FIGS. 5, 8, and 9, the rotating disk 44 is rotated only in one direction, and is driven by the motor 45. By this rotation, the divided portions of the heat storage body 30 are sequentially
Exhaust and air supply are switched, and all parts reliably contribute to heat storage combustion.

In the second embodiment of the present invention, FIGS.
As shown in (1), the rotary disk 44 is reciprocated between a first position 51 and a second position 52, and is driven by a cylinder 45. By this rotation, supply and discharge of the heat storage body 30 are instantaneously switched. The through holes 47 are provided for the partition walls 31A, 31.
The air supply is throttled when the air supply ventilation opening 42 passes through the area between the through holes 47 of the fixed disk since the air supply opening 42 is not opened at the portion corresponding to B, but at that time the fuel supply is also throttled by the valve 6. Therefore, the ratio of primary air to fuel is maintained at a predetermined ratio, and continuous operation is possible without extinguishing the pilot flame.

In the third embodiment of the present invention, as shown in FIG. 6, the ventilation hole 26 formed in the burner tile 22 only partially overlaps the air guide groove 27 formed in the projection 24. Therefore, only a part of the combustion air ejected from the ventilation hole 26 enters the air guide groove 27. Therefore, the directivity is not as strong as in the first embodiment (FIG. 5), but is included in the present invention.

In the fourth embodiment of the present invention, as shown in FIG. 7, the ventilation holes 26 formed in the burner tile 22 do not overlap with the protrusions 24, and the air guide grooves 2 are formed on the side surfaces of the protrusions 24.
7 is not provided. Therefore, the directivity is not as strong as in the first and second embodiments, but is included in the present invention.

In the fifth embodiment of the present invention, as shown in FIG. 12, a rod (for example, a Kanthal rod) made of a heat-resistant conductive material is placed in a single-end tube 103 except for a tip, and an electric insulating material is formed. A leak detection mechanism 105 made of a material covered with an insulator (for example, an insulator) is provided so as to extend to a position immediately adjacent to the bottom portion 104, and a voltage (for example, 1) is applied thereto.
(Approximately 0 V). Single end tube 10
3 is damaged and the molten metal becomes single-ended tube 103
When the tube 103 enters, the current flows between the two conductive rods, and by detecting the current, damage to the tube 103 can be detected. The illustrated example shows a case where two conductive rods are arranged in the tube 103 and a voltage is applied between them. However, when the volume in the tube is small, only one rod is arranged in the tube 103. The same operation and effect can be obtained even if the other one is installed in the furnace body (101). The installation locations of the two rods may be separated from each other as shown in FIG. 12, or may be covered with a protection rod such as a thermocouple, and the tips may be insulated from each other and conduct when the molten metal enters.

[0027]

According to the single-end type radiant tube heating element of the first aspect, the switching mechanism has a sliding contact structure between the rotating disk and the fixed disk, so that a large sliding surface can be obtained and sealing performance can be enhanced. As a result, the supply air pressure can be increased, the combustion air ejection speed can be increased, the flame can be extended toward the tube bottom, and the tube bottom can be heated. Further, the fuel entrainment is improved by increasing the flow velocity of the combustion air, the short path of the fuel to the exhaust is reduced, and the CO concentration in the exhaust is reduced. According to the single-end type radiant tube heating element of the second aspect, the fuel release surface protrudes from the air supply / exhaust surface, so that the fuel is less involved in the exhaust and the axis perpendicular to the axis of the vent hole and the fuel release surface. Direction spacing can be reduced,
As a result, the fuel entrainment of the combustion air having directivity is enhanced, the flame can be extended toward the bottom of the single end tube, and the bottom of the tube can be effectively heated. Further, CO and HC in the exhaust gas can be reduced by the amount of the short path to the exhaust of the fuel. According to the single-ended radiant tube heating element of the third aspect, the burner tile and the heat storage element are housed in the single-ended tube, so that the heat loss to be dissipated can be prevented, and the amount of heat transfer to the tube can be increased accordingly. . In addition, since the distance to the bottom of the tube of the burner tile is also reduced, heating of the bottom of the tube is facilitated. According to the single-end type radiant tube heating element of the fourth aspect, the rotating disk can be rotated in one direction to sequentially use the heat storage element. According to the single-end type radiant tube heating element of the fifth aspect, the rotary disk can be reciprocated and rotated, so that supply and discharge can be instantaneously switched. According to the single-ended radiant tube heating element of the sixth aspect, the fuel opening surface is widened, so that the fuel is easily entrained by the combustion air, and the entrainment of the fuel into the exhaust gas is reduced. According to the single-end type radiant tube heating element of the seventh aspect, since the air guide groove is formed in the projecting portion, the directivity of the combustion air is enhanced, and the tube bottom can be heated more effectively. According to the single-ended radiant tube heating element of the eighth aspect, since the air nozzle separator is provided between the air supply holes, a short path to the exhaust of the combustion air is suppressed, and the generation of CO due to a shortage of air is suppressed. According to the single-ended radiant tube heating element of the ninth aspect, since the leak detecting mechanism is provided, the single-ended tube damage can be promptly and reliably detected. According to the single-end type radiant tube heating element of the tenth aspect, since there is no inner tube, it is not necessary to replace the inner tube, and the life is prolonged.

[Brief description of the drawings]

FIG. 1 is an overall schematic cross-sectional view of a single-end type radiant tube heating element of the present invention.

FIG. 2 is an enlarged sectional view of a portion of a heat storage combustion burner in FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a burner tile portion in FIG. 2;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a schematic plan view of FIG.

FIG. 6 is a schematic plan view of a burner tile portion of a single-ended radiant tube heating element according to a third embodiment of the present invention.

FIG. 7 is a schematic plan view of a burner tile portion of a single-ended radiant tube heating element according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view of a switching mechanism portion of a heat storage combustion burner portion of the single-ended radiant tube heating element according to the first embodiment of the present invention and the vicinity thereof.

FIG. 9 is a plan view of FIG.

FIG. 10 is a cross-sectional view of a switching mechanism portion of a heat storage combustion burner portion of a single-end type radiant tube heating element according to a second embodiment of the present invention and the vicinity thereof.

FIG. 11 is a plan view of FIG. 10;

FIG. 12 is a sectional view of a single-ended radiant tube heating element according to a fifth embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of a furnace equipped with a single-ended radiant tube heating element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Burner for heat storage combustion 2 Air supply passage 3 Exhaust passage 4 Blower 10 Frame 20 Fuel injection nozzle 21 Primary air pipe 22 Burner tile 23 Supply / exhaust surface 24 Projection 25 Fuel open surface 26 Vent hole 27 Air guide groove 30 Heat storage DESCRIPTION OF SYMBOLS 31 Partition wall 40 Switching mechanism 41 Partition wall 42 Air supply ventilation opening 43 Exhaust ventilation opening 44 Rotating disk 45 Drive motor or cylinder 46 Fixed disk 47 Through hole 100 Single end type radiant tube heating element 103 Single end tube 104 Bottom 105 Hot water leak detection mechanism

Continued on the front page (72) Inventor Kazuhisa Mitani 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Ryoichi Tanaka 2-1-153 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Japan Furness Industrial Co., Ltd. (72) Inventor Hiroshi Hirota 3-13-28 Kanayama, Naka-ku, Nagoya City, Aichi Prefecture Inside Fuso Heating Furnace Co., Ltd. (56) References JP-A-6-14724 (JP, A) JP-A-4-43202 ( JP, A) JP-A-4-281102 (JP, A) JP-A-6-221545 (JP, A) JP-A-2-178516 (JP, A) JP-A 8-94013 (JP, A) JP JP-A-7-113509 (JP, A) JP-A-8-233251 (JP, A) JP-A-6-65714 (JP, U) JP-A 53-97741 (JP, U) JP-A 62-204111 (JP , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F23D 14/12 F23C 3/00 301 F23L 15/00-15/02

Claims (10)

(57) [Claims] 1. A heat storage combustion burner and a single-ended tube having one end closed, wherein the heat storage combustion burner is disposed on one side of the heat storage body in the axial direction of the heat storage body, and a plurality of supply and discharge are switched. And a burner tile having a fuel release surface, and a rotating disk and a fixed disk arranged on the other axial side of the heat storage body and slidably in surface contact with each other. A single-ended radiant tube heating element comprising: an exhaust switching mechanism. 2. A heat storage and combustion burner and a single-ended tube having one end closed. The heat storage and combustion burner is disposed on one side of the heat storage body in the axial direction of the heat storage body. A burner tile having a supply / exhaust surface having a plurality of open pores, a protrusion protruding from the supply / exhaust surface, and a fuel release surface formed inside the protrusion, and the other axial side of the heat storage element And an air supply / exhaust switching mechanism provided in the radiant tube heating element. 3. The single-ended radiant tube heating element according to claim 1, wherein a portion of the burner tile and the heat storage element of the heat storage combustion burner is built in the single end tube. 4. The single-ended radiant tube heating element according to claim 1, wherein the rotating disk is configured to rotate in only one direction. 5. The single-ended radiant tube heating element according to claim 1, wherein said rotating disk is reciprocated. 6. The single-ended radiant tube heating element according to claim 2, wherein the fuel release surface is formed so as to extend toward the tip of the protruding portion. 7. The single-ended radiant tube heating element according to claim 2, wherein an air guide extending in an axial direction is formed on an outer peripheral surface of the projecting portion. 8. The single-ended radiant tube heating element according to claim 2, wherein an air nozzle separator protruding in a direction in which the protruding portion protrudes is provided on the air supply / exhaust surface at a position between the ventilation holes. 9. The single-ended radiant tube heating element according to claim 1, wherein a leak detection mechanism extending toward the bottom of the single-ended tube is provided inside the single-ended tube. 10. The single-ended radiant tube heating element according to claim 1, wherein the single-ended tube has an inner tubeless structure having no inner tube.