JPH07159045A - Immersion tube heating type molten aluminum heat insulation furnace - Google Patents

Abstract

(57) [Summary] [Purpose] A heat source with low energy consumption cost. [Composition] A combustion cylinder 3 is immersed in an aluminum melt 21, combustion gas is brought into contact with the combustion cylinder 3 in a region of the combustion cylinder 3 where the combustion cylinder 3 is immersed, and combustion air is alternately passed through a heat storage body. Is provided and the combustion exhaust gas is discharged, and a regenerative burner system 4 that burns the burner while supplying high-temperature combustion air close to the temperature of the combustion exhaust gas is provided, and in the combustion cylinder 3 immersed in the molten aluminum 21. The molten aluminum 21 is heated and kept warm by burning it with the combustion air having a temperature close to the temperature of the combustion exhaust gas. The sensible heat of the combustion exhaust gas is directly recovered by the heat storage in the heat storage body, is used to preheat the combustion air with extremely high efficiency, and is returned to the combustion cylinder again. It can be held and the running cost can be greatly reduced compared to the case of heating with an electric heater.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip tube heating type heat retaining furnace for accumulating molten aluminum and maintaining it at a constant temperature.

[0002]

2. Description of the Related Art In a conventional immersion tube heating type aluminum heat insulation furnace, as shown in FIG. 9, an electric heater 104 is installed inside a partition wall 102 of a immersion tube heating type furnace body 101 lined with a refractory heat insulating material. The heat generated by the electric heater 104 causes the molten aluminum 105 to reach a predetermined temperature, for example, 7
It is designed to keep the temperature above 00 ° C (Shokai Sho 64-
5765). Electric heater 104 is molten aluminum 10
It is installed by being inserted in the ceramic cylinder 103 immersed in the No. 5 container.

[0003]

However, if the molten aluminum is kept at a predetermined temperature by the electric heater 104 having a high energy cost, the running cost becomes high.

An object of the present invention is to provide an immersion tube heating type heat insulation furnace which consumes less energy.

[0005]

In order to achieve the above object, the present invention relates to a dip tube heating type heat retaining furnace for accumulating molten aluminum and keeping it at a constant temperature, and a combustion cylinder immersed in the molten aluminum. , The combustion gas is brought into contact with the combustion cylinder in the portion immersed in the molten aluminum in the combustion cylinder, and the heat storage bodies are alternately passed to supply the combustion air and discharge the combustion exhaust gas, and the temperature is close to the temperature of the combustion exhaust gas. A regenerative burner system that alternately burns a pair of burners in a short time while supplying high-temperature combustion air is provided.

Further, in the present invention, the heat storage type burner system is characterized by alternately burning a pair of burners.

Further, the heat storage type burner system of the immersion tube heating type aluminum molten metal heat retaining furnace of the present invention comprises a heat storage body which is evenly divided into three or more chambers in the circumferential direction and through which fluid can pass axially in each chamber. An inlet / outlet means having a fuel nozzle that penetrates the center of the heat storage body to inject fuel directly into the combustion cylinder, and an air supply chamber connected to the combustion air supply system and an exhaust chamber connected to the combustion gas exhaust system. And the heat storage body and the heat storage body are interposed between the heat storage body and the heat storage body to shut off the heat storage body and the heat storage means, while rotating continuously or intermittently to form the exhaust chamber and the air supply chamber of the water inlet and outlet means into three chambers. The heat storage body is divided into any of the above-described compartments and is sequentially communicated with the heat storage body without overlapping with each other. The fuel is continuously injected into the combustion cylinder, and high temperature combustion air is stored around the fuel. Around the injection point from the body into the combustion cylinder So that direct injection while.

Further, according to the present invention, an inner pipe is installed in the combustion cylinder so as to cover a periphery of an opening for injecting combustion air and fuel of the heat storage type burner system, and a space is provided between the inner pipe and the combustion cylinder. On the other hand, a communication port that communicates the space with the inner side of the inner pipe is provided in the portion of the inner pipe close to the heat storage type burner system, and the combustion gas formed in the inner pipe passes through the space and re-enters the inner pipe through the communication port. To be recirculated while being partly accompanied by the combustion gas, and partly being exhausted through the heat storage body.

[0009]

Therefore, the molten aluminum in the furnace body is heated by the heat obtained by the combustion of the burner and kept at a constant temperature. At this time, when the high temperature combustion exhaust gas is discharged through the heat storage body, the sensible heat is directly recovered by the heat storage body in the heat storage body. Then, the heat recovered in the heat storage body is used for preheating the combustion air with extremely high efficiency by direct heat exchange and is returned to the inside of the combustion cylinder again. Since the temperature of the combustion air can be a high temperature close to the temperature of the combustion exhaust gas flowing out to the heat storage body,
Combustion can be maintained with a small amount of fuel using this high-temperature combustion air, and the combustion cylinder temperature can be rapidly raised. Further, since the combustion gas is ejected only to the portion of the combustion cylinder that is immersed in the molten metal, the portion of the combustion cylinder that is exposed to the space inside the heat retaining furnace is directly exposed to the combustion gas and heated. The combustion cylinder does not crack.

Further, if a heat storage type burner system in which a pair of burners is alternately switched in a short time and burns is adopted,
Since the flame position changes frequently, the temperature distribution in the combustion cylinder can be made more uniform.

Further, in the case of the third aspect of the invention, the air supply chamber and the exhaust chamber of the inlet / outlet means are communicated with different chambers / compartments of the heat storage body through switching means which rotate intermittently or continuously, respectively, and burn. The working air and the combustion exhaust gas simultaneously flow in the heat storage body without intersecting each other. Therefore, the combustion air and the combustion exhaust gas will flow in the same chamber / compartment of the heat storage body at different times, and for example, the combustion air will flow to the heat storage body after the combustion exhaust gas has flowed. The combustion air is preheated and supplied to the high temperature close to the temperature of the combustion exhaust gas by using the heat of the heat storage body heated by the passage. Further, when the heat of the heat storage body decreases, only the combustion exhaust gas and the combustion air are switched by the rotation of the switching means without switching the fuel, so that the injection position of the combustion air is moved in the circumferential direction, and the combustion gas is kept up to now. The combustion air is supplied using the heat storage body of the combustion air supply means that has been exhausted. The combustion air and the fuel that are directly injected into the combustion cylinder are mixed after being injected into the combustion cylinder, but the combustion air has an extremely high temperature (for example, near 1000 ° C. or higher). Therefore, stable combustion is caused. Therefore, the flame formed by the combustion air supplied by shifting the location so as to rotate around the fuel nozzle and the fuel injected at the center rotates in the combustion cylinder in the circumferential direction to move the combustion cylinder. Heat evenly.

Further, in the case of the invention of claim 4, the inner pipe is provided so that the inside of the combustion cylinder is partially made into a double pipe structure so that the inside and the outside of the inner pipe are communicated with each other in the vicinity of the injection port of the combustion air. A part of the combustion exhaust gas flowing back into the inner pipe from the communication port through the space between the inner pipe and the combustion tube is accompanied by the combustion air injected into the inner pipe to increase the capacity of the combustion gas. Therefore,
Even if the combustion cylinder is deep, the flame is prevented from rising and the combustion gas is made to reach the back of the combustion cylinder for heating. Moreover, at this time, the NOx can be reduced by recirculating the combustion gas. On the other hand, at the communication port near the compartment of the heat storage body connected to the combustion gas exhaust system, the combustion gas after being used for heating the combustion cylinder is introduced into the inner cylinder from between the inner pipe and the combustion cylinder and exhausted. To be done.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 and 2 show an embodiment of the immersion tube heating type heat retaining furnace of the present invention. In this immersion tube heating type heat retention furnace, for example, a furnace body 1 in which a steel plate casing is lined with a refractory heat insulating material and a ceiling partition wall 20 forming a molten metal pumping port of the furnace body 1 are suspended inside. And a heat storage type burner system 4 serving as a heat source. In this embodiment, one set of heat storage type burner system 4 is provided for one combustion cylinder 3, but two or more sets of burner systems may be provided depending on the case.

The furnace body 1 is for storing the molten aluminum 21 and keeping it at a temperature suitable for use. For example, the furnace body 1 has a Western bathtub shape as shown in the drawing, and is provided so as to suspend the combustion cylinder 3 in the center. ing. The shape of the combustion cylinder 3 is not particularly limited, but in the present embodiment, a straight pipe having a bottom is adopted. A pair of burners (not shown) that configure the heat storage type burner system 4 are arranged at the upper end opening portion of the combustion cylinder 3. Further, a partition wall 20 is hung from the ceiling at the tap opening portion of the furnace body 1, and is provided so that when the molten aluminum 21 is stored, the furnace space 2 is isolated from the outside and heat dissipation is suppressed. Has been. Although it is not particularly required to provide a partition wall or the like for restricting the flow of the combustion gas in the combustion cylinder 3, for example, a partition 19 shown by a broken line is provided so that the combustion gas flows in a U-shape and burns. You may make it heat the bottom part of the cylinder 3 reliably.

A regenerative burner system 4 is arranged at the end of the combustion tube 3 protruding outside the furnace body 1. In the case of the present embodiment, four combustion cylinders 3 are immersed in the molten metal 21, and a heat storage type burner system 4 including two burners is provided for each combustion cylinder 3. And each burner system 4
The exhaust system and the air supply system are connected to those of the burner system 4 of the other adjacent combustion cylinder 3, and are further provided so as to be finally connected to one exhaust system and the air supply system by the collecting pipe. There is. The heat storage type burner system 4 is not particularly limited in its structure and combustion method, but in the present embodiment, as shown in FIG.
In order to be able to discharge the exhaust gas through the burner and the heat storage body which are not burning and which are in a non-combusted state, the two heat storage bodies 7 and the burner integrated with each other are combined. The one provided in is used. In the case of the present embodiment, the burner body 14 made of a refractory heat-resistant material is shared by the pair of burners 5 and 6, two burner throats are formed side by side, and the heat storage body 7 is inserted in each. . The burner body 14 may be charged into the combustion cylinder 3 such that the open end thereof reaches the liquid level of the molten metal 21 or lower than that so that a flame is formed below the level control range. preferable. in this case,
Since only the portion immersed in the molten metal 21 is heated by the combustion gas, heat is not transferred to the molten metal 21 and becomes an overheated state. The two burners 5, 6 installed in each of the four combustion cylinders 3, 3, 3, 3 are the corresponding burners of the other adjacent burner system 4, that is, the burners that burn at the same time and the burners that stop burning at the same time. After merging the flow paths connected to each other's heat storage bodies 7, 7, the four-way valve 10 is connected to the combustion air supply system 8 for supplying combustion air and the combustion gas exhaust system 9 for discharging combustion gas. By switching the four-way valve 10, either the combustion air supply system 8 or the combustion gas exhaust system 9 can be selectively connected. The combustion air supply systems 8 and 8 bundled in two sets are further merged and connected to one pushing fan 13, and the supply amount of combustion air is controlled by one cylinder of the air amount adjusting valve 18. It is provided. One burner 5 (or 6) is provided so as to supply combustion air through the heat storage body 7, while the other burner 6 (or 5) is provided so as to discharge combustion gas through the heat storage body 7. There is. The combustion air is supplied by the pushing fan 13, and the combustion exhaust gas is pushed out of the combustion cylinder 3 by the new combustion gas ejected into the combustion cylinder 3 and discharged into the atmosphere. Also, the fuel supply system 1
1 also connects two adjacent burner systems 4 and 4 which are in the combustion state at the same time to those of the burners which are in the combustion stop state, and is further provided with a solenoid valve 12 before the other burner systems 4 and 4 are provided. Is connected to one fuel amount adjusting valve 16 by the fuel supply system 11 and the collecting pipe.
The fuel amount adjusting valve 16 is controlled by a controller 17 that detects the temperature of the molten aluminum 21 and determines the fuel supply amount. Therefore, the fuel adjusted by the fuel amount adjusting valve 16 controlled based on the hot water temperature is selectively and alternately supplied to one of the burners 5 and 6. The fuel nozzle 15 is embedded in, for example, the burner throat portion of the burner body 14, only the injection port is opened to the inner peripheral surface of the burner throat, and is provided so as not to be exposed to the combustion gas when passing through the inside. . Further, a part of the combustion air and the fuel is distributed to a pilot burner (not shown).

Here, as the heat storage bodies 7, 7, it is preferable to use a material having a large heat capacity and a high durability for a relatively low pressure loss, for example, a cylindrical body formed of ceramics and having a large number of honeycomb-shaped cell holes. . In this case, when heat is recovered from the combustion exhaust gas, even if the exhaust gas falls below the acid dew point temperature, the sulfur content in the fuel and its chemically modified substances are captured in the ceramics, and the exhaust system ducts, etc. located downstream are subject to low-temperature corrosion. There is nothing to do. Of course, it is not particularly limited to this, and other heat storage bodies such as ceramic balls and nuggets may be used.

According to the immersion tube heating type heat retention furnace configured as described above, the combustion cylinder 3 is heated as follows,
Hold the molten aluminum at a constant temperature.

The pair of burners 5 and 6 are alternately burned to heat the inside of one heat storage body 7 and the combustion cylinder 3. Burner 5 for example
Is burned, the combustion gas is captured below the lowest liquid level of the aluminum melt 21 (the lower limit of the predetermined liquid level fluctuation range), and the combustion gas is immersed in the melt of the combustion cylinder 3 from the burner body 14. Is ejected from the burner throat of the other burner 6 above the combustion cylinder 3 which is stopped, and is discharged through the combustion gas exhaust system 9. That is, in the other burner 6, since the fuel supply system 11 for the burner 6 is closed by the solenoid valve 12 and connected to the combustion gas exhaust system 9 by switching the four-way valve 10, combustion is not performed and combustion exhaust gas Used as a discharge route. The combustion tube 3 is heated from the bottom of the combustion tube 3 by the radiant heat of flame and combustion gas. The aluminum melt 21 warmed from the bottom of the combustion cylinder 3 causes convection, is stirred, and is heated uniformly. Here, since the combustion air supplied to the burner 5 is preheated by direct contact with the heat storage body 7 for a short time and then supplied into the burner body 14, a high temperature close to the exhaust gas temperature (around 760 ° C.)
Is. Therefore, when mixed with the fuel injected from the fuel nozzle 15, even a small amount of fuel is stably combusted to obtain high-temperature combustion gas. Moreover, since the temperature of the combustion air changes immediately with the increase or decrease of the combustion amount, the responsiveness of the temperature adjustment of the combustion gas is good. Therefore, the temperature in the furnace and the combustion cylinder can be rapidly raised to the heat retention temperature. The switching between combustion and exhaust is performed, for example, at an interval of 10 seconds to 2 minutes, preferably within about 1 minute, and most preferably at an extremely short interval of about 10 to 40 seconds. In this case, heat exchange is performed with high temperature efficiency. Also,
The switching may be performed when the combustion gas discharged via the heat storage body 7 reaches a predetermined temperature, for example, about 250 ° C. The atmosphere in the combustion tube 3 is maintained at a temperature suitable for keeping the temperature of the molten aluminum, for example, about 700 ° C.

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG. 4, one heat storage type burner system 4 may be formed between two combustion cylinders 3, 3. In this case, the burners 5 and 6 mounted on the two adjacent combustion cylinders 3 and 3 are connected to one combustion air supply system 8 and combustion gas exhaust through the flow path switching means such as the four-way valve 10. The combustion gas is discharged from the other combustion cylinder 3 when it is connected to the system 9 and burns in the one combustion cylinder 3. In addition to the burner throat 26, a flow passage 27 for exhaust is formed in the burner body 25 that is inserted below the surface of the molten metal in each of the combustion tubes 3 and 3. The flow passage 27 is interconnected by a connecting pipe 28 with the flow passage 27 formed in the burner body 25 in the other adjacent combustion cylinder 3. An intake / exhaust pipe 29 that projects to the vicinity of the bottom of the combustion cylinder 3 is connected to the flow path 27, and is provided so as to suck the combustion gas and discharge the combustion gas near the bottom of the combustion cylinder 3. Therefore, for example, when combustion is performed on one burner 6 side, combustion air that is preheated to the same temperature as the combustion exhaust gas and fuel that is injected from the fuel nozzle 15 while passing through the heat storage body 7 incorporated in the burner body 25. And are rapidly mixed in the burner throat 26 and injected into the combustion cylinder 3,
Diffuse combustion occurs. On the other hand, since the burner 5 of the other adjacent combustion cylinder 3 stops combustion and is connected to the exhaust system 9,
The inside of the combustion cylinder 3 has a negative pressure. Therefore, the adjacent combustion tubes 3
The combustion gas generated therein is sprayed on the bottom of the combustion cylinder 3, then sucked into the intake / exhaust pipe 29 and sucked to the other adjacent combustion cylinder 3 side. Then, it is jetted out in the vicinity of the bottom of the combustion cylinder 3 and drawn into the burner throat 26 while exchanging heat with the bottom and the wall of the combustion cylinder 3, and is exhausted through the heat storage body 7.

The combustion cylinder 3 may be U-shaped as shown in FIG. 5 or W-shaped although not shown.
In this case, one burner system may be constructed by pairing the burners 4 and 5 respectively installed at the opening portions at both ends of the U-shaped or W-shaped tube.

Further, the heat storage type burner system 4 of each embodiment shown in FIGS. 1 to 5 is configured such that two sets of burners 5 and 6 are alternately burned, but the invention is not particularly limited thereto. In some cases, the burner that burns may be fixed, and the heat storage body itself may be rotated between the combustion gas exhaust system and the combustion air supply system, or the combustion air supply system may be used for a fixed heat storage body. Alternatively, a structure may be used in which the flow of the combustion exhaust gas and the combustion air with respect to the heat storage body is relatively switched by alternately switching between the combustion gas exhaust system and the combustion gas exhaust system by the flow path switching device.

6 to 8 show an embodiment in which a heat storage type burner system composed of one burner is incorporated. In this heat storage type burner system 30, a fuel nozzle 31 that directly injects the fuel F into the combustion cylinder 3 is penetrated through the center of the heat storage body 32, and the combustion air A that has been heated to a temperature substantially parallel to the periphery of the jet of the fuel F is used. Is to be jetted.

Here, the system for supplying the combustion air A and exhausting the combustion exhaust gas E is basically divided into three or more chambers 40, 41, 42 evenly in the circumferential direction and the fluid is axially distributed. And an inlet / outlet means 33 having a heat storage body 32 capable of passing through, an air supply chamber 33a connected to the combustion air supply system, and an exhaust chamber 33b connected to the combustion gas exhaust system 9, and the inlet / outlet means 33. The heat storage body 3 is interposed between the heat storage body 32 and the heat storage body 32.
2 and the inlet / outlet means 33 are blocked, while at the same time, the air supply communication hole 35 and the exhaust communication hole 36 which do not exist in the same section
And has an inlet / outlet means 3 which rotates continuously or intermittently.
The three exhaust chambers 33b and the air supply chamber 33a are composed of a switching means 34 for sequentially communicating with any one of the chambers 40, 41, 42 of the heat storage body 32 partitioned into three or more chambers.

The heat storage body 32 is not limited to a particular shape or material, but may be 100% like combustion exhaust gas.
For heat exchange between a high-temperature fluid around 0 ° C. and a low-temperature fluid around 20 ° C. such as combustion air, it is preferable to use a honeycomb-shaped one produced by extrusion molding using a ceramic such as cordierite or mullite as a material. . The honeycomb-shaped heat storage body 1 may be made of a material other than ceramics, for example, a metal such as heat-resistant steel. Also, 50
At medium to high temperatures of around 0 to 600 ° C., it is preferable to use metals such as aluminum, iron, and copper, which are relatively cheaper than ceramics. The honeycomb shape originally means hexagonal cells (holes), but in the present specification, not only the original hexagonal cells but also quadrangular or triangular cells are opened innumerably. Further, as described above, the honeycomb-shaped heat storage body 1 may be obtained by bundling tubes or the like without integrally molding. In the case of the present embodiment, the heat storage body 32 is divided into three chambers in the circumferential direction by the distribution chambers 37, 37 arranged in front of and behind it. For example, in the case of the present embodiment, the distribution chamber 37 divided into three chambers 39a, 39b, 39c by the partition 38,
As shown in FIG. 8, the inside of the heat storage body 32 is divided into three chambers 37 by a chamber 40 in which a fluid does not flow, a chamber 41 for flowing combustion exhaust gas, and a chamber 42 for flowing combustion air. That is, the heat storage body 3
Since 2 itself has a honeycomb shape composed of a set of cells each of which constitutes an independent flow path, the range partitioned by the partition 38 of the distribution chamber 37 forms one partitioned chamber. Will be done. When the distribution chamber 37 is provided, the fluid that flows in through the communication holes 35 and 36 can be dispersed and evenly distributed over the entire area of the heat storage body 32. Also, the shape of the heat storage body 32 is not particularly limited to the honeycomb shape shown in the drawing, and although not shown, a flat or corrugated heat storage material is radially arranged in a tubular casing,
A pipe-shaped heat storage material may be filled in a tubular casing so that the fluid may pass through in the axial direction. Furthermore, in this embodiment, the distribution chamber 37 is used to form a single heat storage body 3.
Although 2 is substantially divided into 3 chambers 40, 41, 42, it is not particularly limited to this, and the heat storage body 32 itself may be divided into 3 chambers in advance. For example, although not shown, a cylindrical casing, which is partitioned into three chambers in the circumferential direction by a partition wall and through which fluid can pass in the axial direction, is prepared, and each of these chambers has a spherical shape, a short tube, a short rod, or a thin rod. One piece,
It may be configured by filling a lump of heat storage material such as a nugget shape or a net shape. When using a heat storage material such as SiN that can be used at a much higher temperature than cordierite or mullite, it is not easy to mold it into a complicated honeycomb shape, but for simple pipe shapes, rods, balls, etc. It is easy to mold.

Here, the number of chambers divided into the heat storage body 32 is defined by a chamber 42 for flowing combustion air (hereinafter referred to as an air supply chamber) 42 and a chamber for flowing combustion exhaust gas (hereinafter referred to as an exhaust chamber) 41. 1
At least one vacant room (a room where fluid does not flow) 4 per group
It is a combination of 0, and the minimum number of rooms is 3 rooms.
Further, the above-mentioned system is also configured by interposing the chamber 40 in which the fluid does not flow between the air supply chamber 42 and the exhaust chamber 41. In this case, the minimum number of rooms is 4
Become a room.

In the case of the present embodiment, the inlet / outlet means 33 is provided with a cylindrical partition wall 44 in a rectangular casing 43, so that the air supply chamber 33 connected to the combustion air supply system 8 and the exhaust system. The exhaust chamber 33b is connected to the exhaust gas chamber 9b. In the case of this embodiment, the supply chamber 33a is formed outside the partition wall 44, and the exhaust chamber 33b is formed inside. In the case of this embodiment, the switching means 34 includes the entrance / exit means 33 and the distribution chamber 37.
It is provided so as to rotate independently between them. Partition wall 4
A seal member 45 is provided between the switch 4 and the switching means 34 to allow the rotation of the switching means 34 and to hermetically prevent the fluid from leaking. The switching means 34 is the entrance / exit means 33.
It is rotatably supported by the partition wall 44 and the fuel nozzle 31 in the center, and a gear 46 is formed on the peripheral edge thereof. The gear 46 meshes with a drive gear 47 arranged at a corner portion of the casing 43, and is rotationally driven by a motor 48. Of course, the present invention is not limited to this, and it may be rotationally driven by a friction wheel that is pressed against the peripheral edge of the switching means 3.

Air supply chamber 33a and exhaust chamber 3 of the entrance / exit means 33
Chambers / compartments 42 of the heat storage body 32, which respectively correspond to 3b,
The switching means 34, which communicates only with 41, is formed of a disc orthogonal to the flow path, and is provided with one compartment of the heat storage body 32 and the air supply chamber 3.
At least one air supply communication hole 35 for communicating with 3a and at least one exhaust communication hole 35 for communicating one compartment with the exhaust chamber 33b are provided. The exhaust communication hole 35 and the air supply communication hole 36 must be such that the air supply communication hole 36 and the exhaust communication hole 35 cannot exist in the same chamber / compartment at the same time. Change from the frontmost communication holes in the chambers / compartments one by one to the front chamber / compartment, and the sizes of the air supply communication holes 36 and the exhaust communication holes 35 should not overlap each other in the radial direction. It is provided so as to satisfy the three conditions that the size is such that all can be accommodated in one room at the same time when arranged. At this time, the air supply communication hole 36 and the exhaust communication hole 35 are set to have substantially the same size and shape, but the present invention is not particularly limited to this, and the air supply communication hole and the exhaust air communication hole 35 are not limited to this. The size and shape may be changed, and if necessary, the size and shape may be changed for each communication hole. Generally, the amount of combustion air and the amount of combustion exhaust gas are set in a substantially balanced relationship, but in some cases, one communication hole may be set larger than the other communication hole.

The fuel nozzle 31 is arranged so as to penetrate the heat storage body 1 and be directly exposed or projected from the combustion cylinder 3. The heat storage body 32 is surrounded by a casing 49 of a fireproof heat insulating material, and is housed in a metal casing 43. The fuel nozzle 31 is also held by the refractory heat insulating material casing 49. Where the fireproof insulation casing 49
Is provided with three injection ports 50, 50, 50 communicating with the chambers 39a, 39b, 39c of the distribution chamber 37 so as to open in the axial direction.

Further, in front of the heat storage body 32 and the fuel nozzle 31, an inner pipe 51 having a plurality of communication ports 52, 52 through which the combustion exhaust gas E can pass is installed. The presence of the inner pipe 51 causes combustion air A injected from the heat storage body 32.
Exhaust gas recirculation can be caused by the injection energy of and the NOx can be reduced by the hydrocarbon radicals generated in the fuel jet. Further, the inner pipe 51 has a double pipe structure in which the inside of the combustion pipe 3 is partially excluding the bottom portion, and connects the outer side and the inner side of the inner pipe 51 in the vicinity of the opening 50 where the combustion air A is injected. There is. Therefore, the space 53 between the inner pipe 51 and the combustion tube 3
A part of the combustion exhaust gas E that flows into the inner pipe 51 again through the communication port 52 is entrained in the combustion air A injected into the inner pipe 51 to increase the capacity of the combustion gas G. Therefore, even if the combustion cylinder 3 is deep, the flame is prevented from rising and the combustion gas G reaches the back of the combustion cylinder 3 and is heated. Moreover, at this time, the NOx can be reduced by recirculating the combustion gas G. On the other hand, in the vicinity of the injection port 50 communicating with the heat storage section 41 connected to the combustion gas exhaust system 9, the combustion exhaust gas after being used for heating the combustion cylinder 3 from the space 53 between the inner pipe 51 and the combustion cylinder 3 E is introduced into the inner pipe 51 and exhausted.

According to the burner configured as described above, the combustion tube 3 can be uniformly heated by the rotating flame by performing the switching operation between air and exhaust as follows.

First, in the state of FIG. 8, the entrance / exit means 3
When the combustion air A is introduced into the air supply chamber 33a of No. 3, the combustion air A flows into the second chamber 39c of the distribution chamber 37 through the air supply communication hole 35, and further the corresponding heat storage body 32 Room of
It flows into the compartment 42. At this time, since the corresponding compartment / chamber 42 of the heat storage body 32 is heated by the heat of the high temperature combustion exhaust gas E that has passed before the switching, the passing combustion air A takes away the heat of the heat storage body 32. High temperature, that is, the heat storage body 32
Is heated to a temperature close to the temperature of the combustion exhaust gas, and is injected from the periphery of the fuel nozzle 31 disposed in the center of the heat storage body 32 directly into the combustion cylinder 3 in parallel with the fuel F ((A in FIG. 7). ) State). On the other hand, the exhaust chamber 33b of the entrance / exit means 33
The combustion exhaust gas E in the combustion tube 3 is introduced into the corresponding section 41 of the heat storage body 32 communicated with the exhaust gas through the exhaust communication hole 36 by the function of the induction fan of the exhaust system 9. And
The combustion exhaust gas whose temperature is lowered by heating the section 41 of the heat storage body 32 is supplied to the first chamber 39 of the distribution chamber 37.
b into the exhaust chamber 33b through the exhaust communication hole 36.
Is discharged to.

Next, when the switching means 3 is continuously or intermittently rotated in the clockwise direction from the state shown in FIG. 8, the exhaust communication hole 36 is first provided with the third chamber 39a of the left adjacent distribution chamber.
Therefore, the first chamber 39b and the third chamber 39a simultaneously communicate with the exhaust chamber 33b. Therefore, the combustion exhaust gas E in the combustion tube 3 passes through the two compartments 41 and 40 of the heat storage body 32, and then the first chamber 39b and the third chamber 39a of the distribution chamber 37.
To the exhaust chamber 33b connected to the two chambers 39a and 39b through the exhaust communication hole 36.
And it is exhausted. After that, the exhaust communication hole 36 is completely switched to the third chamber 39a (the part that was the empty chamber indicated by the reference numeral 40 in FIG. 8), and then the second chamber 39c.
The communication hole 35 for air supply that was occupied by the first chamber 39b is switched to the first chamber 39b (the chamber portion indicated by reference numeral 41 in FIG. 8), and the second chamber 39c (the chamber indicated by reference numeral 42 in FIG. 8). The area partitioned by is an empty room. In other words, the combustion exhaust gas E is flown into the chamber 40 where the fluid has not been flowed until now, the combustion air A is flown into the chamber 41 where the combustion exhaust gas E has been flowed until now, and the combustion air A is further passed. The fluid is not flowed into the chamber 42 in which the fluid was flowed. Therefore, the heat storage body 32 is heated by the heat of the combustion exhaust gas E, and the heated heat storage body 3
The combustion air A passing through 2 is warmed by the heat of the heat storage body 32. At this time, switching of the fluid flow is performed while communicating with each of the two chambers even when the chamber 40 is occupying the two chambers, so that the fluid flow is not interrupted. Then, the combustion exhaust gas E is sequentially switched to the combustion air A next to the combustion exhaust gas E without interruption. Therefore, the combustion air A passes through the heated heat storage body 32 and becomes hot air having a high temperature close to the exhaust gas temperature and is supplied into the combustion cylinder 3 (state (B) of FIG. 7). Therefore, by the continuous or intermittent rotation of the switching means 34, the position where the combustion air A is injected is sequentially changed in the circumferential direction as shown in FIGS. The flame rotates in the circumferential direction.

Here, the high temperature combustion air A and the fuel F injected from the fuel nozzle 31 are separately injected into the combustion cylinder 3, spread to the combustion cylinder 3, and inside the combustion cylinder 3 separated from the fuel nozzle 31. Mixed in. At this time, since the combustion air A and the fuel F rapidly reduce their flow velocities and widen the mixing region, it is a condition that is originally difficult to burn.
However, since the combustion air A itself has a high temperature, it easily burns even under such conditions. That is, it burns slowly.
This slow combustion produces less NOx. The combustion gas generated by the slow combustion is used in the combustion cylinder 3 as described above, then passes through a part of the heat storage body 32 and is discharged to the outside of the furnace. Here, switching of the heat storage body 32 is performed, for example, 20 times.
It is performed at intervals of seconds to 90 seconds, preferably about 10 seconds, or when the combustion gas discharged via the heat storage body 32 reaches a predetermined temperature, for example, about 200 ° C.

[0035]

As is apparent from the above description, in the immersion tube heating type heat retaining furnace of the present invention, the combustion cylinder is immersed in the molten aluminum and the heat storage body is passed through in the region immersed in the molten metal in the combustion cylinder. Since the aluminum melt is heated and kept warm by burning it with combustion air that has a temperature close to the temperature of the exhaust gas, it is possible to maintain the temperature of the aluminum melt at a temperature suitable for keeping heat even with a small amount of fuel. Compared with the case of heating with a heater, the running cost can be significantly reduced and the heating efficiency can be increased. Moreover, since only the portion immersed in the molten aluminum is heated by the combustion gas, overheating in the furnace space of the combustion cylinder can be prevented and cracking can be avoided. Therefore, while securing the same safety and durability as in the case of the conventional electric heater, it can contribute to the improvement of thermal efficiency and energy saving by recovering exhaust heat, and the overall energy cost can be reduced to about 1/3. I was able to. Moreover, when compared with the conventional immersion tube heating type heat retention furnace using an electric heater, the thermal efficiency can be increased and the energy consumption can be reduced, so that the CO ₂ generated to obtain that amount of energy can be reduced to about 36 It can be reduced to about 10%, which can greatly contribute to the improvement of the global environment.

Further, in the molten aluminum heat insulation furnace of the present invention, when a pair of burners are alternately switched and burned in a short time, the flame position changes frequently, so that the heat pattern in the combustion cylinder can be made more uniform, The uneven heating and uneven heat are reduced, and the equipment is compact and easy.

Further, in the case of the immersion tube heating type aluminum molten metal heat retaining furnace of the third aspect of the present invention, the combustion air is supplied so that the location is changed so as to rotate in the circumferential direction around the fuel nozzle, and the flame burns. Since the inside of the cylinder is rotated in the circumferential direction, the combustion cylinder can be heated uniformly.

Further, in the case of the invention of claim 4, a part of the combustion gas exhausted through the space between the inner pipe and the combustion cylinder is accompanied by the combustion air injected into the combustion cylinder. Therefore, it is possible to increase the volume of the combustion gas and to reach the inside to heat the combustion gas even if the combustion cylinder is deep,
Further, it is possible to reduce NOx by recirculating exhaust gas.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the immersion tube heating type heat retention furnace of the present invention.

FIG. 2 is a vertical cross-sectional view of the heat insulating furnace of FIG.

FIG. 3 is a schematic principle view showing one embodiment of a heat storage type burner system applied to the immersion tube heating type heat retention furnace of the present invention.

FIG. 4 is a vertical cross-sectional view showing another embodiment of the heat storage type burner system used in the heat retaining furnace of the present invention.

FIG. 5 is a vertical sectional view showing still another embodiment of the immersion tube heating type heat retention furnace of the present invention.

FIG. 6 is a longitudinal sectional view showing still another embodiment of the immersion tube heating type heat retention furnace of the present invention.

7 is an operation (A) in which the flame rotates in the circumferential direction in the heat storage type burner system used in the embodiment of FIG.
It is explanatory drawing of- (C).

FIG. 8 is a principle diagram of a switching unit used in the heat storage type burner system of FIG.

FIG. 9 is a schematic view showing a conventional immersion tube heating type heat retention furnace.

[Explanation of symbols]

 1 Furnace Body 2 Furnace Space 3 Combustion Cylinder 4 Heat Storage Burner System 5, 6 Pair of Burners 21 Aluminum Molten Metal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhisa Mitani 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Ryoichi Tanaka 2-53, Shite, Tsurumi-ku, Yokohama, Japan Nippon Furnace Kogyo Co., Ltd. (72) Inventor Hirota Hirota 3-13-28 Kanayama, Naka-ku, Nagoya, Aichi Prefecture Fuso Heath Co., Ltd.

Claims (4)

[Claims] 1. A dip tube heating type heat retention furnace for accumulating and maintaining a constant temperature of molten aluminum, a combustion cylinder immersed in the molten aluminum, and a portion of the combustion cylinder immersed in the molten aluminum. Combustion gas is brought into contact with the combustion cylinder, and the heat storage bodies are alternately passed to supply combustion air and discharge combustion exhaust gas to burn the burner while supplying high-temperature combustion air close to the temperature of the combustion exhaust gas. An immersion tube heating type aluminum molten metal heat retaining furnace, which is provided with a heat storage type burner system. 2. The immersion tube heating type aluminum molten metal heat retaining furnace according to claim 1, wherein the heat storage type burner system alternately switches a pair of burners in a short time to burn. 3. The heat storage type burner system has three
A heat storage body that is evenly divided into more than one chamber and allows fluid to pass through each chamber in the axial direction, a fuel nozzle that penetrates the center of the heat storage body and directly injects fuel into the combustion cylinder, and a combustion air supply An inlet / outlet means having an air supply chamber connected to the system and an exhaust chamber connected to the combustion gas exhaust system, and interposed between the inlet / outlet means and the heat storage body to cut off between the heat storage body and the inlet / outlet means. On the other hand, the switching means is configured to rotate continuously or intermittently to sequentially communicate the exhaust chamber and the air supply chamber of the inlet / outlet means without overlapping with any one of the compartments of the heat storage body partitioned into three or more compartments. The fuel is continuously injected into the combustion cylinder, and high temperature combustion air is directly injected around the fuel from the heat storage body into the combustion cylinder while moving the injection position in the circumferential direction. Immersion tube heating type aluminum molten metal heat retention according to 1. . 4. An inner pipe is provided in the combustion cylinder to cover a periphery of an opening for injecting combustion air and fuel of the heat storage type burner system, and a space is provided between the inner pipe and the combustion cylinder. On the other hand, a communication port that communicates the space with the inner side of the inner pipe is provided at a portion of the inner pipe close to the heat storage type burner system, and the combustion gas formed by the inner pipe passes through the space. The immersion tube heating type according to claim 3, wherein the immersion tube reflows into the inner tube again through the communication port, is partly accompanied by combustion gas and is recirculated, and partly is exhausted through the heat storage body. Aluminum molten metal heat insulation furnace.