JP3274931B2 - Aluminum chip melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aluminum chip melting furnace. More specifically, the present invention relates to an improvement in a burner system serving as a heat source of an aluminum chip melting furnace.

[0002]

2. Description of the Related Art An aluminum chip melting furnace is shown in FIG.
As shown in FIG. 2, the aluminum swarf introduced into one corner of the furnace is melted using a combustion gas blown into the furnace from a burner 102 attached to a side wall of the melting furnace 101 as a heat source, and is temporarily stored. It is configured to be taken out to a pot or the like. Burner 1 is located at the bottom of melting furnace 101.
The molten aluminum melted by the heat of No. 02 is stored, and the aluminum chips poured with this molten aluminum are melted.

[0003] In the aluminum melting furnace having such a structure, a burner 102 for continuously and steadily burning is conventionally used as a heat source. By controlling the flow control valves 105 and 106 provided in the combustion air supply system 103 and the fuel supply system 104 with a control signal from the combustion load controller 107, the combustion amount of the burner 102 is controlled, and the temperature in the furnace and, consequently, the furnace temperature. It is provided to adjust the temperature of the molten aluminum to a predetermined temperature. On the other hand, melting furnace 101
An exhaust system 108 for exhausting exhaust gas from the exhaust fan 10
9 and the exhaust damper 110 are provided.
The furnace pressure is kept constant by adjusting the opening degree (opening / closing degree) of the furnace with a furnace pressure controller. Incidentally, since the burner 102 is a continuous steady-state combustion, there is little fluctuation in the furnace pressure. Therefore, the furnace pressure is sufficient only by detecting the furnace pressure and controlling the damper 110 of the exhaust system 108 to keep the furnace pressure at a constant value. Control.

[0004]

However, in this conventional aluminum chip melting furnace, the combustion gas obtained by the continuous steady-state combustion of the burner 102 is used for melting the aluminum chip and then exhausted as it is. However, there is a problem that the heat loss increases. Conventionally, in order to reduce waste heat loss, heat recovery using a recuperator or the like is generally performed. However, conventional recuperators cannot be used at high temperatures, so that air must be mixed into the exhaust gas to reduce the heat to below the allowable heat resistant temperature of the recuperator, and heat recovery must be performed, and only a waste heat recovery rate of 50% or less can be obtained. There's a problem. Therefore, there is a problem that the melting cost is increased.

[0005] Further, since dust such as aluminum fume which volatilizes at the time of the flux treatment is mixed in the exhaust gas, the dust is discharged to the exhaust damper 110, the recuperator (not shown) of the exhaust system 108, the exhaust fan 109 and the like. It often adheres and hinders operation.

[0006] Therefore, an object of the present invention is to provide an aluminum chip melting furnace that increases the waste heat recovery rate and lowers the energy consumption cost. Another object of the present invention is to provide an aluminum chip melting furnace capable of stable operation.

[0007]

In order to achieve the above object, an aluminum chip melting furnace with a flux treatment according to the present invention uses a flow path switching means as a heat source to store the supply of combustion air and the discharge of combustion exhaust gas. A regenerative alternating combustion burner system in which at least a pair of burners are alternately burned alternately through the body is used, and a ceramic having a honeycomb-shaped flow path that is linearly penetrated as a regenerator is used. ing.

[0008] In the present invention, in conjunction with regenerative alternate combustion damper or valve burner installed exhaust damper exhaust system of a system to control the supply amount of combustion air or the fuel opening and closing of the exhaust damper, It is preferable to open and close these at a fixed ratio.

[0009]

Therefore, by burning a pair of burners alternately, when the high-temperature exhaust gas passes through the heat storage body on the other burner side and is exhausted, the sensible heat is directly recovered to the heat storage body by heat exchange. . Then, the heat recovered in the heat storage body is used for preheating for supplying combustion air with extremely high temperature efficiency by direct heat exchange, and is returned to the furnace again. At this time, the temperature of the combustion air can be set to a high temperature close to the temperature of the exhaust gas flowing out to the regenerator, so that combustion can be maintained with a small amount of fuel and the furnace temperature can be rapidly raised. Moreover, since honeycomb-shaped ceramics are used as the heat storage,
The stagnation of the flow of combustion air or exhaust gas can be eliminated, and the flow of exhaust gas and air supply alternately occurs in opposite directions, whereby the self-cleaning action of the flow path (backwash) works, and the exhaust gas in the heat storage medium It is possible to prevent dust such as flux from adhering.

[0010]

Further, in the case where the opening and closing of the exhaust damper is opened at a fixed ratio in conjunction with the supply of combustion air or the supply of fuel,
Even if the pressure inside the furnace changes when the alternate combustion is switched by the flow path switching means, the opening degree of the exhaust damper interlocked with the combustion air supply system or the fuel supply system does not change, causing a hunting phenomenon of the furnace pressure. Nothing.

[0012]

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

FIGS. 1 to 8 show an embodiment of an aluminum chip melting furnace according to the present invention. As shown in FIG. 1, FIG. 1 and FIG. 2, this aluminum chip melting furnace includes a melting furnace (furnace body) 1 capable of storing a fixed amount of molten aluminum (aluminum molten metal), and a side wall of the melting furnace 1. And a heat storage type alternating combustion burner system 2 serving as a heat source provided in the portion. In this embodiment, two burners are combined.
Although the regenerative alternating combustion burner system 2 of the system is provided, two or more systems may be provided.

The melting furnace 1 does not have the features of the present invention in its structure, material and the like, and therefore detailed description is omitted. However, in general, the melting furnace 1 is used for melting and storing a fixed amount of the input aluminum chips. At least a space 3 for storing the molten aluminum in the center, a gutter 4 for taking out the molten aluminum, and a charging means 5 including a chute and a charging port for charging the aluminum chips are provided. Have.

The regenerative alternating combustion burner system 2 is arranged toward a central space 3 of the melting furnace 1. The heat storage type alternating combustion burner system 2 is not particularly limited in its structure and combustion method.
The two casings 9 and 7 are connected to a burner body 10 and integrated to burn them alternately and burn them alternately, and exhaust gas is discharged through the non-burning burner and the regenerator. Are used. For example, as shown in FIG. 3, a combustion air supply system 11 for supplying combustion air to the burners 6 and 7 and an exhaust system 12 for discharging exhaust gas from the melting furnace 1 are interposed by flow path switching means 14. To selectively connect to the heat storage material 8 of each of the burners 6 and 7. One burner is supplied with combustion air through the heat storage material 8, while the other burner is supplied through the heat storage material 8 in the melting furnace 1. It is provided to exhaust the combustion gas. As shown in FIGS. 5 and 6, a dust collector 15 is built in the flow path switching means 14, and the combustion exhaust gas which has passed through the heat storage body 8 and has become low temperature is passed therethrough, and aluminum fume and the like therein are passed through. It is provided so as to capture dust. The combustion air is supplied from a combustion air supply system 11 connected to one of the ports of the flow path switching means 14 by, for example, a pushing fan 18 and the exhaust gas is connected to one of the ports of the flow path switching means 14. Exhaust system 12
The air is sucked by an exhaust means such as the attraction fan 19 and discharged into the atmosphere. Further, the fuel supply system 13 selectively supplies fuel to one of the two burners 6 and 7 via a flow path switching means such as a three-way valve 16. Fuel injection is performed in two stages of primary fuel and secondary fuel. For example, a primary fuel nozzle 17a buried in a burner throat portion of the burner body 10 and having only an injection port opened on the inner peripheral surface of the burner throat, and a secondary fuel nozzle 17b injected from a furnace inner end face of the burner tile 24. It is provided so as to be injected in two stages and mixed with the entire amount of combustion air flowing through the burner throat to perform two-stage combustion. Each nozzle 1
7a and 17b are burner tiles 24 and burner bodies 10
And is provided so as not to be exposed to the combustion gas when passing through the inside. A part of the combustion air and fuel is distributed to the pilot gun 25.

In the case of the present embodiment, the flow path switching means 14 for switching the path between the exhaust gas and the combustion air is shown in FIGS.
Rooms 26a, 26b, 2 divided into four rooms as shown in FIG.
Channel switching means for selectively opening and closing 6c and 26d with a switching plate 27 is used.

The flow path switching means is divided into four rooms 26a, 26b,
26c, 26d, of which two rooms 26a, 26
c, a combustion air supply system 11 and an exhaust system 12 are connected,
A casing 9 for accommodating the heat storage bodies 8 of the pair of burners 6, 7 is connected to the remaining two rooms 26b, 26d. The four rooms 26a, 26b, 26c, 26d are formed with communication holes 28ad, 28ab, 28cb, 28 formed in the partition wall 29.
Neighbors are communicated with each other by cd. Also,
A rotary shaft 30 is provided at a central intersection of the X-shaped partition wall 29, and four communication holes 28 a, 28 b, 28 of the partition wall 29 are provided.
a switching plate 27 for selectively closing two of c and 28d;
27 are attached. The switching plates 27, 27 are 180
The connection between the combustion air supply system 11 and the exhaust system 12 to the pair of burners 6 and 7 is alternately switched by the swing rotation. For example, in the state of FIG.
a and 26d, 26b and 26c are communication holes 28ad and 28c
b and the combustion air supply system 11 and the burner 7
Side, the exhaust system 12 and the burner 6 side are connected to each other, but the switching plates 27, 27 are oscillated in the clockwise direction to rotate the chambers 26a and 26b, 26c and 26d into the communication holes 28a.
b and 28cd, the burner 7 side and the exhaust system 12 and the burner 6 side and the combustion air supply system 11 are connected respectively. A dust collector 15 is provided at the bottom of the rooms 26b and 26d. This dust collector 1
5 is a nozzle-like duct 32 disposed coaxially with the ports 31b and 31d to which the heat storage bodies 8 and 8 on the burners 6 and 7 side are connected, respectively, and a hopper 33 surrounding the periphery thereof and having a narrowed lower end outlet. It is composed of The flue gas discharged from the port 31b or 31d once passes through the nozzle duct 32 and then reverses, rises around the nozzle duct 32, flows out of one of the open communication holes into the adjacent chamber, and flows into the exhaust system. It is discharged to 12. At this time, dust such as aluminum fume also travels straight after passing through the nozzle-shaped duct, falls into the hopper 33, and is separated from the combustion exhaust gas. The dust collected in the hopper 33 is taken out by opening a valve 35 provided at the bottom of the hopper 33.

The combustion air supply system 11 and the fuel supply system 13 are provided with flow rate control valves 20 and 21 for controlling the flow rate. In the alternating combustion, after the combustion of the burner is once stopped, the supply path of the fuel and the combustion air is switched to the stopped burner side and then re-ignited, so that the furnace pressure fluctuates at the moment of the switching. Therefore, in the control system that detects the furnace pressure and keeps the furnace pressure constant, the exhaust damper may be excessively closed at the time of combustion switching, thereby causing a hunting phenomenon of the furnace pressure. Therefore, the exhaust damper 22 installed in the exhaust system 12
Is provided so as to be controlled by a control signal from a controller 23 that controls the combustion load. For example, as shown in FIG.
An exhaust damper 22 is installed between the fuel cell and the flow path switching means 14.
The flow control valve 20 is operated at a fixed ratio in conjunction with the flow control valve 20 by a control signal for controlling the combustion load. For example, when the supply amount of the combustion air is set to 1, the exhaust damper 22 is set to an opening capable of exhausting the exhaust gas of 1.1, and the exhaust gas is exhausted only when the combustion air is not supplied to any of the burners 6 and 7. The damper 22 is closed. It is preferable to use a slow-open type exhaust damper that opens and closes gently to prevent hunting of the furnace pressure.

As the heat storage body 8, a honeycomb-shaped ceramic, such as cordierite or mullite, having a constant passage cross-sectional area as shown in FIG. This honeycomb-shaped ceramic has a large heat capacity and a high durability, but has a relatively low pressure loss. In addition, exhaust and air supply are alternately performed without stagnation. For this reason, dust such as aluminum fume in the exhaust gas hardly adheres to the honeycomb-shaped flow path of the heat storage body 8, and even if it adheres, the dust is backwashed and does not become dirty.
Furthermore, even if the exhaust gas falls below the acid dew point temperature when heat is recovered from the exhaust gas, the sulfur and the chemical change substances in the exhaust gas are trapped on the surface of the ceramics and the downstream exhaust system 12
It does not corrode ducts at low temperature. The heat storage body 8 can be replaced by opening the lid 35 of the casing 9.

According to the aluminum chip melting furnace configured as described above, aluminum chip can be melted as follows.

By the alternating combustion of the pair of burners 6, 7,
When each of the heat storage bodies 8 and the melting furnace 1 reach a predetermined temperature, aluminum chips are fed from the feeding means 5. Combustion gas generated by the combustion of the regenerative alternating combustion burner system 2 is used for heating the aluminum chips in the melting furnace 1, and then is exhausted from the burner throat of the other stopped burner through the exhaust system 12. . That is, the burner during which combustion is stopped is used as a combustion gas discharge path. Then, the combustion air passing through the heat storage unit 8 is supplied after being preheated to a high temperature close to the exhaust gas temperature by direct contact with the heat storage unit 8 for a short time. Therefore, stable combustion can be performed even with a small amount of fuel, and a high-temperature combustion gas can be obtained. In addition, the temperature of the combustion air changes instantaneously as the amount of combustion increases or decreases, so that the responsiveness of adjusting the temperature of the combustion gas is good. Therefore, the temperature in the melting furnace 1 can be rapidly raised to the melting temperature of the aluminum chips.
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 is exchanged with high temperature efficiency. Further, the switching may be performed when the combustion gas discharged via the heat storage body 8 reaches a predetermined temperature, for example, about 200 ° C.

The aluminum chips are heated by the radiant heat of the combustion gas. At this time, since the flame position changes frequently due to the alternating combustion, the heat pattern in the melting furnace 1 can be made more uniform and the heating can be performed efficiently. When a certain amount of dissolved aluminum accumulates, the combustion of the burner system 2 is reduced to such an extent that the molten aluminum can be maintained at the melting temperature or higher. Then, the newly added aluminum chips fall into the molten aluminum and are melted. The molten aluminum is taken out of the gutter 4 to the ladle 34 or the like by opening the tap hole of the melting furnace 1 with a tapping device or the like.

On the other hand, the exhaust gas sometimes contains dust such as aluminum fume. However, the heat storage body 8
Inside, the flow passage has a constant passage cross-sectional area and penetrates linearly, so that there is no stagnation in the flow of the fluid and there is little adhesion of dust. In addition, since exhaust and air supply are performed alternately, backwashing occurs and adhesion of dust is prevented.
Then, the dust passes through the heat storage body 8 while being contained in the exhaust gas and becomes low in temperature, and then is introduced into the dust collector 15 and collected. Therefore, dust does not adhere to the flow path switching means 14 and the exhaust fan 19 downstream of the dust collector 15 to cause any trouble.

The above embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, as a flow path switching unit for selectively connecting a combustion air supply system and a combustion gas exhaust system to a heat storage unit,
In the present embodiment, a four-way valve is exemplified, but the present invention is not particularly limited to this, and a combination of four solenoid valves or another type of flow path switching valve may be used.
Further, the dust collector 15 may be provided independently between the heat storage body 8 and the flow path switching means 14 without being built in the flow path switching means 14.

[0025]

As is apparent from the above description, the aluminum chip melting furnace of the present invention recovers the heat of the combustion exhaust gas with a heat storage body and burns it with combustion air supplied at a high temperature close to the combustion exhaust gas. The furnace is heated to a temperature suitable for maintaining the temperature of the molten aluminum, so that the temperature inside the furnace can be raised even with a small amount of fuel, and the heat transfer amount can be increased to shorten the heating time. In addition, the running cost can be reduced. Therefore, it is possible to contribute to improvement of thermal efficiency and energy saving by exhaust heat recovery. Compared with the aluminum smelting furnace using the conventional combustion method, the thermal efficiency can be increased and the energy consumption can be reduced, so the CO ₂ generated for obtaining the energy can be greatly reduced, It can greatly help to improve the global environment. Moreover, the heat storage body made of honeycomb-shaped ceramics that penetrates linearly can eliminate the stagnation of the flow of combustion air or exhaust gas, and the exhaust and air supply alternately flow in opposite directions. Accordingly, the self-cleaning action (backwashing) of the flow path works, and it is possible to prevent dust such as flux in the exhaust gas from adhering.

[0026]

Further, when the opening and closing of the exhaust damper is linked with the supply of combustion air or the supply of fuel at a constant ratio,
Even if the pressure inside the furnace changes when the alternate combustion is switched by the flow path switching means, the opening degree of the exhaust damper interlocked with the combustion air supply system or the fuel supply system does not change, causing a hunting phenomenon of the furnace pressure. Nothing.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic structure of an aluminum chip melting furnace of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a front view showing one embodiment of a regenerative burner system applied to the aluminum chip melting furnace of the present invention.

FIG. 4 is a side view showing a cross section of a part of the burner of FIG. 3;

FIG. 5 is a cross-sectional view showing an embodiment of the flow path switching means and a dust collector incorporated therein, with the positions of ports connected to the exhaust system and the combustion air supply system shifted for convenience.

6 is a vertical sectional view taken along the line VI-VI in FIG.

FIG. 7 is a perspective view showing an example of a honeycomb ceramic heat storage body.

8A and 8B are diagrams showing an example of control of the aluminum chip melting furnace of the present invention, wherein FIG. 8A is a block diagram, and FIG. 8B is a graph showing a change in furnace pressure.

FIG. 9 is a schematic view of a conventional aluminum chip melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Heat storage type alternating combustion burner system 8 Honeycomb-shaped ceramic heat storage body 12 Exhaust system 14 Flow path switching means 15 Dust collector 22 Exhaust damper

──────────────────────────────────────────────────続 き Continued on the front page (73) Patent holder 592017002 Sanken Sangyo Co., Ltd. 1-72, Higashi-Sendacho, Naka-ku, Hiroshima-shi, Hiroshima (72) Inventor Matsuo Shibata 2-chome, Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1:53 Inside Japan Furnace Industry Co., Ltd. (72) Inventor Kazuyoshi Fukuma 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Eiji Mizutani 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Company Stock Inside the company (72) Inventor Haruhide Tanaka 145-1, Yufutsu, Tomakomai City, Hokkaido Inside Toyota Motor Hokkaido Co., Ltd. (72) Inventor Masatoshi Teranishi 1-1-72 Higashisenda-cho, Naka-ku, Hiroshima-shi, Hiroshima Sanken Within Sangyo Co., Ltd. (56) References JP-A-1-222102 (JP, A) JP-A-59-93187 (JP, A) JP-A-1-61542 (JP, U) Akira 51-47131 (JP, B2) (58 ) investigated the field (Int.Cl. ^7, DB name) F27B 3/00 - 3/28 C22B 21/00 - 21/06 F23L 15/02 F27D 17/00 101

Claims (2)

(57) [Claims] 1. A wake the Hare aluminum chips melting furnace fluxing with aluminum chips was dissolved in burner heat a certain amount of storage, the burner discharge of the combustion exhaust gas and the supply of combustion air by the channel switching means And alternately through a regenerator to form a regenerative alternating combustion burner system in which at least a pair of burners are alternately burned, and that the regenerator has a honeycomb-shaped flow passage that is linearly penetrated. An aluminum chip melting furnace characterized by the following. 2. An exhaust damper is installed in an exhaust system of the burner system, and the opening and closing of the exhaust damper is interlocked with a damper or a valve for controlling a supply amount of combustion air or fuel, and the exhaust damper is opened and closed at a fixed ratio. aluminum chips melting furnace according to claim 1 Symbol mounting, characterized in that.