JPH0567873B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to molded products such as bricks, ceramics, fine ceramics, iron, and non-ferrous metals, or powder products that are handled by being filled into heat-resistant containers. This invention relates to a rotary hearth elevator type furnace for heat treatment.

<Conventional technology> Conventional furnace equipment can be broadly divided into (1) intermittent operation type furnaces and (2)
There is a continuous operation furnace.

(1) Intermittent operation type furnace When the heat treatment conditions such as the amount of heat treatment, treatment temperature, treatment time, etc. of the product are changed each time the operation is performed, the trolley-type furnace shown in Figures 6a and b, and Figure 7a are generally used. , b, or the elevator type furnace shown in FIG. 8 are used.

Each time these furnaces are operated, the products to be heat-treated are loaded onto a cart and charged into the furnace at a low temperature close to room temperature, and the temperature of the furnace body and the cart is raised by the combustion heat of the fuel. It is preheated, heated, soaked, and further cooled to complete a predetermined heat treatment operation. That is, the operation is performed according to a series of programs to complete one operation.

Intermittent operation furnaces have the following advantages:

(A) Heat treatment conditions can be changed each time the operation is performed.

(B) Therefore, a wide variety of products can be easily heat treated.

(C) The furnace can be operated and stopped freely, making it suitable for heat treatment of small quantities of products.

(D) Maintenance is easy when the furnace is out of service.

However, it has the following drawbacks.

(b) A large amount of heat is absorbed by increasing the temperature of the furnace body and cart each time it is operated, and most of it is discarded as lost heat.

In addition, part of the fuel combustion heat supplied to the furnace is consumed to raise the temperature of the product, furnace body, trolley, etc., but the rest becomes waste gas at approximately the same temperature as the inside temperature of the furnace and flows into the flue and chimney. It is then disposed of into the atmosphere. Incidentally, waste heat may be recovered in the exhaust gas path to preheat the air or as another heat source, but the amount of heat is only a small amount. That is, the above-mentioned waste heat loss is extremely large, and the thermal efficiency is extremely low.

(b) Since the operation is repeated every time, the operating rate of the furnace equipment is poor, that is, the productivity is low.

(c) Programmed operation that automatically controls the temperature inside the furnace each time is easy, but automation that includes charging and extracting products into the furnace is extremely complicated.

(d) The lifespan of the furnace body is short because the temperature of the furnace body is repeatedly raised and cooled frequently.

(2) Continuous operation type furnace A continuous operation type furnace is usually used when there are few changes in heat treatment conditions and operation under approximately the same conditions continues for a relatively long period of time. As representative examples, FIGS. 9a, b, and c show a tunnel type bogie furnace, FIGS. 10a, b show a rotary hearth type furnace, and FIGS. 11a, b show a roller hearth type furnace. Figure 9a,
In the tunnel type furnace shown in b and c, the furnace chambers are arranged and connected in the order of pre-heating zone, heating/soaking zone, and cooling zone from the furnace entrance, and the products loaded on the cart can freely pass through the furnace. It consists of a tunnel-shaped furnace chamber that communicates with each other. The high-temperature furnace gas generated in the fuel combustion area of the heating and soaking zone flows to the pre-heating zone and is disposed of into the atmosphere from near the furnace entrance through the flue and chimney. On the other hand, the products loaded on the trolley are charged from the furnace inlet, are preheated, heated, and soaked while being transferred to the preheating zone, heating/soaking zone, and then cooling zone. While being transferred, it is cooled by cooling air, etc., and extracted from the furnace outlet, completing the prescribed heat treatment operations.These operations are performed continuously by continuously charging carts from the furnace entrance. is to be carried out. In addition, in the above-mentioned continuous operation, normally, the temperature inside the furnace is completed in advance to an atmosphere suitable for the target heat treatment conditions at the beginning of the operation, or regular operation is started as soon as there is a prospect of temperature increase. .

This tunnel type furnace has the following main advantages.

(A) The fuel combustion heat supplied in the heating and soaking zone is effectively used to preheat the product in the preheating zone, and the air used for cooling the product is recovered in the cooling zone and used as preheated air for fuel combustion. The degree of effective use of heat is extremely high.
In addition, the heat absorbed by the furnace body is only at the initial stage of operation, and there is no loss of heat absorbed by the furnace body during subsequent continuous operation. Therefore,
Thermal efficiency is extremely good.

(B) It is easy to automatically control the temperature inside the furnace and automate the charging and extraction of products into the furnace, allowing stable operation to be maintained.

(C) It is easy to maintain stable heat treatment conditions, and the heat treatment effect on the product is constant, improving quality and yield.

(D) Productivity is very high due to continuous operation.

(E) The frequency of heating and cooling of the furnace body is reduced, and the life of the furnace body is therefore extended.

However, it has the following drawbacks.

(b) Poor responsiveness to changes in heat treatment conditions;
That is, the difficulty in responding to changes in the furnace temperature and reductions in the throughput of products is a common drawback of continuous operation furnaces.

(b) In the case of the tunnel-type bogie furnace shown in Figure 9 a, b, and c, it is difficult to adjust the pressure balance near the boundary between the end of the soaking zone and the cooling zone, and it is difficult to adjust the pressure balance between the soaking zone and the cooling zone. Inflows and outflows are likely to occur. As a result, problems such as atmospheric disturbance and increased heat loss arise. In addition, because it is difficult to completely seal between the furnace cart and the furnace body, gas in the furnace or cold air under the cart tends to flow in and out between the inside of the furnace and the bottom of the cart, resulting in uneven temperature distribution inside the furnace and heat loss. This may cause an increase in the amount of water and abnormal damage to the bottom of the truck. A further disadvantage is that it requires an operation to return the cart extracted from the furnace outlet, which is farthest from the furnace entrance, to the entrance side.

(c) In the case of the roller hearth type furnace shown in Figure 11a and b, it is possible to heat the product from the top and bottom,
Although the temperature distribution will be uniform, there are many challenges such as the material, strength, and arrangement of hearth rollers used at high temperatures of 1,100 to 1,200 degrees Celsius or higher.
There are significant restrictions on conditions such as heat treatment temperature and product size, shape, and weight. Further, depending on the size and shape of the product, a tray may be required, which has the disadvantage of requiring a tray return operation outside the furnace.

(d) In the case of the rotary hearth type furnace shown in Figure 10 a, b, the tunnel type furnace shown in Figure 9 a, b, c is made into an annular shape, and the products charged from the furnace inlet are placed in the rotary hearth. Since the product is transferred to the furnace outlet adjacent to the inlet and extracted by one revolution, it is very convenient for transferring the product within the furnace, but it has the disadvantage that the temperature distribution within the furnace tends to be extremely uneven. Furthermore, when molded products such as bricks are stacked high on a hearth and heat treated, loading and extracting the products into the furnace becomes difficult.

The present invention aims to improve the many drawbacks of the above-mentioned conventional intermittent operation type furnaces and continuous operation type furnaces at once. Productivity that can accommodate small or large quantities, energy saving and labor saving, and a furnace room group and product loading work area on the same circumference,
A rotary hearth elevator type furnace with improved performance such as arranging the product unloading work area to make effective use of the narrow installation space, and allowing efficient movement to each independent furnace chamber without the troublesome operation of opening and closing the shutter. Our goal is to provide the following.

<Means for solving the problems> The rotary hearth elevator type furnace according to the present invention has the following features:
Among a plurality of independent furnace chambers arranged in a ring at predetermined intervals on the same circumference, the soaking chamber with the highest temperature is placed in the center, and from the entrance side, the preheating chamber, the preheating chamber, and the flue are arranged. a heating chamber communicating with the heating chamber via a flue, a soaking chamber communicating with the heating chamber via a flue, and a product loading work area adjacent to the preheating chamber on the same circumference while sequentially arranging one or more cooling chambers; A product preparatory work area and a product unloading work area adjacent to the cooling room are arranged, and each of the furnace rooms, the product loading work area, the product preparatory work area, and the product unloading work area can be moved up and down at the same time, and at a position below each furnace room. It is equipped with a removable hearth plate that moves along the annular arrangement direction while repeating a downward movement, an arcuate movement, and an upward movement.

<Operation> First, the products to be heat treated are loaded onto the hearth board of the product loading work area, which is raised to the same height as the hearth of the furnace chamber. Next, after simultaneously lowering the hearth plate in the work area loaded with products and the hearth plate in each furnace room to a predetermined position, each hearth plate is moved in an arc to the adjacent furnace room or work place. Move and raise each hearth plate to the hearth position again. For heat treatment of products, the products transferred from the workplace are stored in a preheating chamber and preheated for a predetermined period of time. Also, during the preheating time, the next product to be charged is loaded onto the hearth board in the product loading workshop, and the product waits until the next charging time. below,
The product, which has been preheated by repeating the same operations as described above, is sequentially transferred to a heating chamber and a soaking chamber, and then sequentially transferred to a first cooling chamber and a second cooling chamber, where heat treatment is performed respectively. The product is preheated, heated,
Completes the entire soaking and cooling process. The products cooled in the second cooling room in the final process are unloaded from the hearth board in the product unloading workshop.

<Example> An example of the present invention will be described below with reference to the drawings. An example of the structure of the main part is shown in the heat treatment temperature curve in FIG. 4 and in FIGS. 1 to 5, and the outline thereof will be explained. In addition, Fig. 1 shows W-W' in Fig. 2,
A plan sectional view, Figure 2 is a cross-sectional view taken along line X-X' in Figure 1,
FIG. 3 is a cross-sectional view cut in the direction of the Y-Y' and Z-Z' arrows in FIG. 1 and arranged in series, and FIG. 5 is a cross-sectional view of the bottom of the furnace chamber.

(1) Furnace chamber and work area As shown in the heat treatment temperature curve shown in Fig. 4 and the corresponding Fig. 3 and Fig. 1, the furnace chamber 1, that is, the soaking chamber 1c, which has the highest temperature, is divided into one group of furnace chambers. Furnace chambers 1 each having an independent function, such as a preheating chamber 1a, a heating chamber 1b, a soaking chamber 1c, a first cooling chamber 1d, and a second cooling chamber 1e, are arranged in the center from the inlet side. A group of furnace chambers arranged in an array, and a product loading work area 3 where products M to be charged into the furnace chamber 1 are loaded onto a hearth board 2.
Then, a product unloading work area 4 where the product M extracted from the second cooling room 1e at the end of the furnace chamber group 1 is unloaded from the hearth board 2 and a product preparatory work area 5 are located along the circumference with a predetermined dimension R as the radius. , and are arranged on the work deck 6 at the same interval P.

(2) Hearth board, rotary hearth frame, rotating device, and lifting device Immediately below the work deck 6 mentioned above, there are a group of furnace chambers, a product loading work area 3, and a product unloading work area 4 arranged at equal intervals on a concentric circle. , a rotary hearth frame 7 with annular wheels 8 on which an equal number of hearth plates 2 are set, and a pedestal 9 for supporting these are provided. On this pedestal 9, a hearth board 2 and a rotating hearth frame 7 are mounted.
A rotating device 10 is provided for integrally rotating the hearth plate 2 with the center of the array circumference serving as a rotation core. Further, this pedestal 9 is horizontally supported by a plurality of elevating devices 11, such as hydraulic lifters, which are provided to raise and lower the pedestal 9. The top of the product M loaded on the hearth board 2 is lowered by the lifting device 11 to a height where it does not touch the lower part of the work deck 6 below the furnace chamber 1, and the rotating hearth frame 7 is moved freely by the rotating device 10. (See Figure 3).

(3) Structure of the furnace chamber (A) Each furnace chamber 1 is composed of a preheating chamber 1a, a heating chamber 1b, a soaking chamber 1c, a first cooling chamber 1d, and a second cooling chamber 1e, and each furnace chamber 1 is made of steel. Fireproof material on the inside of the case,
The furnace chamber 1 has a cylindrical or box-shaped side wall and a ceiling lined with a heat insulating material, etc., and the bottom of the furnace chamber 1 supports the hearth board 2 loaded with the product M by raising and lowering a pedestal 9. The furnace chamber 1 is open for charging or extraction. In addition, when the product M is stored in the furnace chamber 1 at the bottom of the furnace chamber 1,
A heat-resistant packing 12 and a double sealing device 14 such as a sand seal 13 or a water seal are provided to completely seal between the lower surface of the furnace chamber 1 and the upper surface of the hearth plate 2 (see FIG. 5).

(B) The soaking chamber 1c located at the center of the furnace chamber group is equipped with a fuel combustion burner 15 at a position that makes the temperature distribution in the furnace uniform. Also, soaking room 1c
The soaking chamber 1c and the heating chamber 1b are connected to a sufficiently insulated flue 16 so that the high-temperature furnace gas generated in the heating chamber 1c is introduced into the heating chamber 1b adjacent to the entrance side of the soaking chamber 1c and reused. It is communicated with.

(C) In the heating chamber 1b, the product must be sufficiently and uniformly preheated before being transferred to the soaking chamber 1c. The means for this is first to reuse the furnace gas introduced from the soaking chamber 1c, but it is also equipped with a high-speed jet injection device 17 for high-temperature gas recovered in the first cooling chamber 1d. Aiming at forced stirring and waste heat recovery. Furthermore, the high-speed jet blower 17 is used in combination with an auxiliary burner for fuel combustion, so that the temperature inside the furnace chamber can be raised even higher if necessary. The furnace gas in the heating chamber 1b is further introduced into the preheating chamber 1a adjacent to the inlet side of the heating chamber for reuse.
The preheating chamber 1a is communicated with the preheating chamber 1a through a flue 16 which is sufficiently insulated.

(D) In the preheating chamber 1a, the waste gas introduced from the heating chamber 1b is used to sufficiently and uniformly preheat (and dry) the product before being transferred to the heating chamber 1b. Equipped with a heat-resistant fan 18 for forced stirring. Preheating chamber 1a
The waste gas is discharged into the atmosphere from the flue 16 at the end of the furnace chamber through the chimney 19, but it is also possible to recover waste heat by equipping the exhaust gas path with a combustion air preheating device 19' or the like. .

(E) In the cooling room, the high-temperature product extracted from the soaking room 1c is cooled down to a predetermined temperature, but in order to match the cooling temperature of the product, the first cooling room 1d (high temperature side) and the second cooling room 1e are used. They are installed separately on the low-temperature side, and both use a cooling method using air blowing. That is, in the case of this example, as shown in FIG. 3, first, fresh air preheated by a combustion air preheating device 19' installed in the waste gas path of the preheating chamber 1a is supplied to the second cooling chamber 1e. The waste air is then blown into the furnace chamber, and the waste air is then blown into the first cooling chamber 1d to cool the respective products. The product is cooled in this way, and at this time, the waste air (air) that has become high in temperature due to heat exchange with the product is sent to the soaking chamber 1c and heating chamber 1b described above to be used as air for fuel combustion. , or heating chamber 1
Used as a high-speed jet air flow for forced stirring of gas in the furnace (b).

In addition, when blowing into the first cooling chamber 1d and the second cooling chamber 1e as cooling air, outside air (cold air)
The temperature of the blown air can be adjusted by mixing the air.

(4) Structure of the hearth board The hearth board 2 is compatible with the bottom shape and dimensions of each furnace chamber 1, that is, the preheating chamber 1a, the heating chamber 1b, the soaking chamber 1c, the first cooling chamber 1d, and the second cooling chamber 1e. It is a steel frame made of steel, etc., with a combination of refractory and heat insulating materials, and is set in an easily removable manner on a rotating hearth frame 7 with wheels 8, and can be used as a spare hearth board. It has a structure that allows easy replacement (see Figure 5).

(5) Work area on the work deck A product loading work area 3 for loading products M onto the hearth board 2, a product unloading work area 4, and a product preliminary work area 5 are provided on the work deck 6. The above-mentioned operations are performed during storage, heating, and cooling operations.

(6) Heat insulation and sealing device for the furnace chamber and under the hearth plate To prevent the temperature of the product from dropping due to the outside air under the furnace chamber when the heated product in the furnace chamber is lowered to the bottom of the furnace chamber together with the hearth plate 2. is equipped with a heat insulating/sealing device 20 that is linked to the vertical movement of the hearth board 2.
In this example, a case is shown in which a heat insulating board and a heat insulating sheet with good heat insulating properties are used, and the heat insulating sheets are provided along the circumference and inscribed circle connecting each furnace room and the work area, respectively, over the entire circumference.

(7) Atmosphere in each furnace room Usually, each furnace room heat-treats products in an oxidizing atmosphere. However, it is necessary to create a non-oxidizing atmosphere in each furnace chamber for preheating, heating, and soaking, and to collect nitrogen gas or non-oxidizing combustion waste gas from the furnace chamber as a cooling medium in the cooling chamber and adjust the temperature to an appropriate temperature before using it. It is also possible to heat-treat the product in a state where the entire furnace chamber or a part thereof is made into a non-oxidizing atmosphere. In this case, it is advisable to use a heat exchanger to indirectly preheat the combustion air using waste gas from a cooling chamber or the like.

Next, the operating method of this embodiment will be explained based on FIGS. 1 to 5.

(1) First, when the hearth plate 2 and the rotating hearth frame 7 are raised by the operation of the lifting device 11, the product M to be heat treated is placed on the hearth plate 2. and waits until the time for charging into the preheating chamber 1a.

(2) The lifting device 11 is activated by a program signal with a charging time set in advance to lower the pedestal 9, and then the rotating device 10 is driven to move the rotary hearth frame 7 one pitch, that is, product loading. It rotates from the center of the work area 3 to the center of the preheating chamber 1a. continuation,
With the center of the hearth plate 2 aligned with the center of the preheating chamber 1a, the lifting device 11 is operated to raise the pedestal 9,
The product M on the hearth board 2 is stored in the preheating chamber 1a. At this time, the other hearth boards 2 also move in the same way.

(3) With the product stored in the furnace chamber 1, the product is preheated for the time set in the program. Also, at the same time, the next product to be charged is loaded onto the hearth board 2 at the product loading workshop 3 on the inlet side of the furnace chamber 1, and waits until the charging time as described in 1 above.

(4) Thereafter, by repeating the same operations as in (1), (2), and (3) above, the preheated product is placed in the heating chamber 1b.
It is transferred to the soaking room 1c, and further, the first cooling room 1d,
The product is sequentially transferred to the second cooling chamber 1e and subjected to heat treatment, thereby completing all steps of preheating, heating, soaking, and cooling.

(5) The product cooled in the second cooling chamber 1e in the final process reaches the product unloading work area 4 on the furnace outlet side and is unloaded from above the hearth board 2.

(6) All of the above operations can be performed automatically according to a preset program.

(7) Furthermore, temperature control of the heating chamber 1b, soaking chamber 1c, first cooling chamber 1d, and second cooling chamber 1e, fuel combustion control, etc. are automatically performed according to a program.

<Effects of the Invention> Since the present invention has the above configuration, it has the following unique effects. In other words, (1) A furnace chamber group, a product loading work area, a product preparatory work area, and a product unloading work area are arranged at specified intervals on the same circumference, and the hearth board provided in each furnace room and each work area is Because it has a structure that simultaneously descends and moves in an arc, then rises and moves to the adjacent position, the furnace room group and each work area can be located on the same circumference, making it possible to install equipment in a narrow installation space. This allows for effective use of land.

(2) High operability and productivity.

(a) Although it functions as a continuous furnace, each furnace chamber is independent, so various conditions such as the charged product, heat treatment temperature, and furnace atmosphere for each furnace chamber can be changed each time the furnace is operated. This enables heat treatment operations for a wide variety of products.

(b) By adjusting the amount of product charged per batch,
Able to respond immediately to changes in production volume.

(c) Because the furnace chambers are independent, there is no radiant heat exchange between each furnace chamber or heat exchange due to the inflow and outflow of gas in the furnace chamber, and as a result, the heat loss that occurs in continuous furnaces is suppressed, and the temperature rise in each furnace chamber is reduced. , the operability and controllability of cooling etc. are improved.

(d) Improving the uniform heating and cooling performance of products by equalizing the temperature distribution inside the furnace both structurally and operationally with an independent furnace chamber and strengthening the sealing between the furnace chamber and the hearth, and improving the above item (c). Due to improvements in temperature, holding, and cooling performance, it is possible to shorten heat treatment time compared to conventional furnaces, and from this aspect as well, operability and productivity can be improved.

(3) It is an energy-saving furnace.

(a) Fuel combustion gas can be effectively used for preheating and heating charged products by flowing in stages from the soaking chamber to the heating chamber and preheating chamber.

(b) Product cooling air (hot air) in the cooling room can be recovered and effectively used as fuel combustion air or recirculated hot air.

(4) It is a labor-saving furnace.

(a) A plurality of independent furnace chamber groups arranged in a ring at predetermined intervals on the same circumference, a product loading work area, a product preparatory work area, and the cooling room adjacent to the preheating room on the same circumference; An adjacent product unloading workshop is located, and the inlet hearth plate automatically returns to its entry point by rotating the hearth frame, so there is no need to return the hearth plate.

(b) All product charging, heat treatment, extraction, and repair work can be performed on the same circumference, and there is no need for troublesome shutter opening/closing operations, allowing for efficient work.

(c) Furnace temperature, combustion control, hearth board (product) transfer, etc. can be easily and completely automatically performed according to the program.

(5) Improving product quality and yield.

As the heat treatment temperature of products becomes more uniform, both product quality and yield improve.

(6) Easy maintenance.

(a) Because the furnace is an independent furnace, local repairs are extremely easy.

(b) Since the hearth plate is easy to attach and detach, even if the hearth plate refractory, which is the most easily damaged, is damaged, it can be simply replaced with a spare hearth plate, and there is no need to stop heat treatment operations at all.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and W in FIG.
-W' plane cross-sectional view, Figure 2 is a cross-sectional view of 4 is a heat treatment temperature curve diagram in each furnace, FIG. 5 is a sectional view of the bottom of the furnace chamber, and FIGS. 6 a, b to 11 a, b
6 shows a conventional example, FIGS. 6 a and b are cross-sectional views and vertical cross-sectional views of a bogie type furnace, FIGS. 7 a and b are cross-sectional views and a vertical cross-sectional view of a Carvel type furnace, and FIG. 8 is an elevator type furnace. A vertical cross-sectional view of the furnace; Figures 9a, b, and c are a cross-sectional view, a vertical cross-sectional view, and a heat treatment temperature curve diagram of a tunnel type bogie furnace; Figure 10 is a cross-sectional view and a vertical cross-sectional view of a rotary hearth type furnace. In FIG. 11, a and b are longitudinal sectional views of a roller hearth type furnace, and XX' sectional views. 1... Furnace room, 2... Hearth board, 3... Product loading work area, 4... Product unloading work area, 10... Rotating device, 11... Lifting device.

Claims (1)

[Claims] 1 A soaking chamber with the highest temperature among a plurality of independent furnace chambers arranged in a ring at predetermined intervals on the same circumference is placed in the center, and the preheating chamber and the smoke are connected from the entrance side. A product loading work area in which a heating chamber communicates with the heating chamber via a flue, a soaking chamber communicates with the heating chamber via a flue, and one or more cooling chambers are sequentially arranged and adjacent to the preheating chamber on the same circumference. A product preparatory work area and a product unloading work area adjacent to the cooling room are arranged, and each of the furnace chambers, the product loading work area, the product preliminary work area, and the product unloading work area can be raised and lowered simultaneously, and is located below each furnace chamber. A rotary hearth type elevator type furnace characterized by being provided with a removable hearth plate that moves while repeating a downward movement, an arcuate movement, and an upward movement in sequence along an annular arrangement direction.