JPH07294149A - Automatic temperature raising method for tunnel furnace - Google Patents

Abstract

PURPOSE:To automatically start the tunnel furnace of a paused state by sending an unburned material carrying truck from an inlet while forming a temperature in the furnace necessary to bun by automatically starting a burner and a blower. CONSTITUTION:A furnace 1 is sequentially partitioned from an inlet 2a to an outlet 2b to a preheating zone 3, a burning zone 4, a soaking zone 5, a quenching zone 6 and a slow cooling zone 7. Preheating furnaces 8 of six trucks are provided before the inlet 2a. When the furnace 1 is raised at its temperature from its paused state, dummy trucks of truck numbers 1 to 13 are first disposed, the trucks of truck numbers 14 to 27 in which products burned before the furnace is paused are located and blank trucks are disposed at the furnaces 8. Burners are controlled at the respective zones by partitioning the zone 4 to four zones. In order to control the entire temperature raising steps, a programmable controller, a personal computer for altering a control system, and monitoring the operating furnace, an automatic controller for conducting a process control, and a recorder for collecting process data are used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically raising the temperature of a tunnel furnace for a ceramic industry used for firing roof tiles, etc.

[0002]

2. Description of the Related Art As is well known in the art, a tunnel furnace has a preheating zone, a firing zone, a soaking zone, and
It is a continuous firing furnace that is divided into a quenching zone and a slow cooling zone in order, and firing is carried out while a truck loaded with the products to be fired travels from the entrance to the exit. For this purpose, for example, it is necessary to form a predetermined temperature curve in the furnace as shown in FIG.
During operation, the temperature of each part in the furnace is detected by a thermometer, and the furnace temperature is controlled by the burner combustion amount and the air flow of the blower so that the temperature of each part does not deviate from the set value.

However, it is not easy to raise the temperature of the furnace in a cold state by suspending it for periodical inspections and repairs to form the predetermined temperature curve in the furnace.
For this reason, conventionally, a skilled worker performs burner ignition, blower start, control of running vehicle timing, etc. based on intuition and experience to start the furnace, but during that time, there is no sleepless work. Will be required. In addition, such a temperature raising operation of the furnace is less frequent than a few times a year, so that it is difficult for a skilled person to grow. When an unfamiliar worker performs this work, it takes a lot of time, and most of the products put in the furnace by the time the temperature rise is completed are often defective products. For this reason, it is necessary to place a dummy carriage for the purpose of only stabilizing the temperature of the furnace in the entire furnace to start the work, and to introduce a new dummy carriage into the furnace even during the temperature rising process, which is wasteful. There was a problem that there were many.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and is the same as a case where a tunnel furnace in a dormant state is performed by an expert without relying on the intuition and experience of a skilled worker. It was made to provide an automatic temperature raising method for a tunnel furnace that can automatically start up without waste.

[0005]

An automatic temperature raising method for a tunnel furnace according to claim 1, which is made to solve the above-mentioned problems, comprises:
It is characterized in that a burner and a blower are automatically started for a tunnel furnace in a dormant state to form a furnace temperature necessary for firing, and a white truck is fed from an inlet. Here, the white background trolley means a trolley on which an unfired product to be a product is loaded. It should be noted that more specific temperature raising means shown in claims 2 and below will be described in detail together with examples described later.

[0006]

According to the automatic temperature raising method for the tunnel furnace of the present invention,
A dummy truck is placed only at the entrance to the tunnel furnace to the center.
The burner and the blower are automatically started from the state where the truck loaded with the products baked before the furnace is stopped is placed in the other parts. And while sending the white ground truck from the entrance of the furnace,
Form the furnace temperature required for firing. For this reason, the number of dummy carriages can be reduced, and the product loaded on the white carriage becomes a non-defective product when leaving the furnace, and waste can be eliminated. Moreover, the time required to raise the temperature can be shortened to about 1.5 days. Hereinafter, more specific contents of the present invention will be described together with examples.

[0007]

EXAMPLES [Structure of Furnace] First, referring to FIG. 1, the structure of a tunnel furnace in an example will be described. The total length of the furnace 1 of the embodiment is
86m, the number of trucks in the furnace is 27, entrance 2
From a to the outlet 2b, it is divided into each zone of a preheating zone 3, a firing zone 4, a soaking zone 5, a quenching zone 6, and a slow cooling zone 7. Further, in front of the entrance 2a of the furnace 1, a preheating furnace 8 for 6 vehicles is provided. The preheating furnace 8 is maintained at about 150 ° C. by the hot air collected from the slow cooling zone 7, where the carriage is preheated and then fed into the preheating zone 3 from the inlet 2a of the furnace 1. In the preheating furnace 8, the truck is moved by a chain pusher installed below the truck.

Reference numeral 9 is a main pusher installed at the inlet 2a of the furnace 1, by which the carts are pushed into the furnace one by one. The speed is a slight speed of 20 to 40 minutes per car,
The line pressure moves all the trucks in the furnace at the same time. Controls such as starting, stopping, speed change, etc. are performed by signals from the instrument room.
As shown in FIG. 1, in each zone of the furnace 1, there are 17 thermometers R-1 to R-17 for monitoring shown by white circles and 5 thermometers TC1 to TC5 for control shown by black circles. is set up.
Then, in the steady operation state, the firing is performed at the furnace temperature as shown in the upper part of FIG.

In the preheating zone 3, in addition to exhaust holes for exhausting the combustion gas generated in the firing zone 4, cooling air injection holes for preventing temperature rise are provided. A large number of burners with automatic ignition / misfire monitoring devices are installed in the firing area 4. For the burner combustion control, a constant air ratio control method and a constant combustion air pressure control method are adopted. Soaking zone 5 is firing zone 4
And the quenching zone 6 as a separation zone. As shown in FIG. 2, in the quenching zone 6, by directly injecting cooling air into the furnace, exchanging heat with an indirect cooling jacket installed on the ceiling, or sucking in the furnace air, the temperature inside the furnace is 1100.
This is a zone where the temperature is lowered from ℃ to 650 ℃ in a short time. In the slow cooling zone 7, it is necessary to gradually lower the temperature range of 600 ° C to 550 ° C, which is the transformation point of the product to be fired. As shown in Fig. 2, direct injection of cooling air into the furnace and suction of the air in the furnace are required. , Soaking the heat in the furnace by using an axial fan.

[Arrangement of Bogie at Start of Temperature Raising] When the temperature of the tunnel furnace as described above is raised from the rest state by the method of the present invention, first, the bogie numbers 1 to 13 (that is, from the inlet to the inlet of the quenching zone 6) ) Place a dummy trolley and trolley number 14
From 27 to 27 (that is, from the quenching zone 6 to the outlet), there is a trolley for loading the products baked before the furnace is stopped. Further, the above-mentioned white background trolley is arranged in the preheating furnace 8, and it is not the dummy trolley that is fed into the furnace during or after the temperature rising process but the white background trolley loaded with the unbaked product to be the product.

[Outline of temperature raising process-Activation of blower] After the carriage is arranged as described above, the blower is activated. Although a total of 22 blowers are used in the embodiment, the role of each blower is as follows. Blowers F1 and F2 are in preheating zone 3
For controlling the furnace pressure, the blower F3 for exhausting the trapit, the blower F4 for controlling the pressure of the combustion primary air of the burner, and the blower F
5 and F6 are for controlling the pressure of the combustion secondary air, the blower F7 is for driving the preheating furnace 8, the blower F8 is for exhausting the preheating furnace 8, the blowers F9 and F10 are for heat recovery, and the blower F11 is for the quenching zone 6. For temperature control, blower F12 is for temperature control of slow cooling zone 7,
The blowers F13 to F15 are axial flow fans (F9 to F15) in the slow cooling area 7.
2), the blower F16 is for cooling under the bogie, the blower F17 is for controlling the furnace pressure in the quenching zone 6, the blowers F18 to F20 are for outlet pressure feeding, the blower F21 is for outlet heat exhaust, and the blower F22 is for outlet heat recovery. It is for. Of these blowers, F3, F
4, F13 to F15 and F18 to F20 are automatically started under predetermined conditions, but the other blowers are manually started before the start of temperature rise. In addition, the blowers F1, F2,
F4, F5, F6, F11, F12, and F17 are incorporated in the control loop, and their target values automatically change according to the temperature rise.
Further, the blowers F7, F9, F10 and F21 automatically increase the air volume thereof as the temperature rises.

[Outline of temperature raising process ... Starting of burner] As described above, many burners are installed in the firing zone 4,
In the embodiment, the firing zone 4 is divided into 4 zones and the burner is controlled for each zone. Then, at the same time when the blower is started, the burner in the fourth zone (the zone closest to the soaking zone 5) of the firing zone 4 is ignited, and after that temperature reaches a predetermined temperature, the burners in the front zone are sequentially burned. Ignite. The situation is shown in FIG.

In order to control the entire temperature rising process, a programmable controller for starting and stopping the equipment, changing the target value, etc., and changing the control method and monitoring the furnace according to the situation are performed. A personal computer, a controller for process control, and a recorder for collecting process data are used.

[Suppression of Temperature Increase in Preheating Area ... Corresponding to Claims 2 and 3] As described above, the temperature inside the furnace gradually increases, and the thermometer R-1 at the inlet of the furnace indicates, for example, 270. When the temperature reaches ℃, the main pusher 9 starts pushing the white background truck into the furnace. However, at this stage, the temperature of the slow cooling zone 7 has not been raised, so that the preheating furnace 8 heated by the hot air from the slow cooling zone 7 has not yet reached 150 ° C. For this reason, when the white background truck is pushed from the preheating furnace 8 into the preheating zone 3 in the furnace as in the normal operation, a rapid heating causes a defective product. Therefore, in this case, cooling air is injected into the preheating zone 3 from outside the furnace to prevent an excessive temperature rise in the preheating zone 3. In the embodiment, the injection of the cooling air is started when the temperature of the thermometer R-1 exceeds 300 ° C, and stopped when it becomes 270 ° C or less.

Further, when the thermometer R-1 exceeds 250 ° C., one trolley is sent to suppress an excessive temperature rise in the preheating zone 3, but the chilled trolley was brought into the furnace. When the reading of the thermometer R-1 becomes less than 250 ° C, the carriage is stopped, and the next carriage is sent after the temperature is recovered.

[Control of temperature rise in firing area ...
In order to perform the temperature rise most easily, a dummy carriage may be arranged in the entire furnace and the dummy carriage may be continuously fed into the furnace until the temperature rise is completed. We are raising the temperature while sending a white background truck loaded with unfired products that should become products. Therefore, the temperature curve of the calcination zone 4 is established when the trolley that is input in the first maneuver passes through the calcination zone 4, and the temperature curve of the quenching zone 6 and the gradual cooling zone 7 is established at the time when it passes through the quenching zone 6 and the slow cooling zone 7. Must be However, in order to maintain the temperature in the firing zone 4, it is sufficient to delay the delivery, but this does not bring heat into the rapid cooling zone 6 and the slow cooling zone 7, so the temperature rise of those portions is delayed. On the contrary, in order to quickly raise the temperature in the rapid cooling zone 6 and the slow cooling zone 7, it is sufficient to increase the feeding speed, but this cannot maintain the temperature in the firing zone 4. The inventions of claims 4, 5 and 6 aim to maintain these contradictory conditions in good balance.

[Vehicle moving speed ... Claim 4] In this embodiment, thermometers R-6 and R- provided in the maximum temperature range.
7. Thermometer TC-4 or TC-5 is 1120 ℃
When it exceeds the limit, the transportation to the firing zone 4 is started. And 1
After confirming the temperature of these thermometers after the carriage, if the temperature is 1115 ° C or higher, carry out the next carriage and increase the speed of carriage movement to shorten the carriage time. On the contrary, if the temperature is lower than 1115 ° C, stop the movement of the carriage and wait for the temperature to recover, or slow down the movement speed of the carriage. In this way, the speed of the carriage movement is changed in accordance with the temperature in the furnace and the feeding is continued to raise the temperature of the slow cooling zone 7.
If the condition that 16 is 400 ℃ or more is satisfied, further increase the sending speed to bring it to the final sending speed. By controlling the sending speed in this manner, it is possible to quickly raise the temperature of the rapid cooling zone 6 and the slow cooling zone 7 while preventing the temperature from decreasing in the maximum temperature zone.

[Setting of temperature controller ... Claim 5] At the start of vehicle operation in the above temperature rising process, the temperature inside the furnace rapidly decreases in the firing zone 4, so that Although it is necessary to change the zone temperature setting value according to the temperature rise situation, normal PID control cannot immediately respond to a rapid temperature drop. Therefore, in the invention of claim 5, a method is adopted in which a set value higher than the final furnace temperature is given to the temperature controller, and this set value is shifted to the furnace temperature necessary for firing by a predetermined calculation. There is. For example, the third of the firing zone 4
In the zone, the temperature set value of the thermometer TC-3 in the normal operating state is 970 ° C, but it is higher than this in the temperature raising process.
Automatic temperature control is performed with 1050 ° C as the temperature setting value. Then, the temperature set value is decreased by 5 ° C. every 30 minutes. And
After reaching 970 ℃, shift to normal control. By performing such temperature control, the target value of the automatic temperature control is always set to a high value, so that it is possible to prevent a sharp decrease in temperature.

[Setting of Temperature Controller ... Claim 6] During normal operation of the tunnel furnace of the present embodiment, the thermometer TC-4 installed in the fourth zone of the firing zone 4, which is the highest temperature zone, is used. The maximum temperature (1125 ° C) may be controlled, but as shown in Fig. 4, the temperature curve of the firing zone 4 at the beginning of the transfer tends to be the maximum temperature in the zone near the furnace inlet, unlike during normal operation. Indicates. Therefore, if only the thermometer TC-4 is used for control, the temperature of the thermometer R-6 will exceed 1125 ° C.
Cause product defects. Therefore, the thermometers R-6 and T shown in FIG.
Of C-5, TC-4, and R-7, it is necessary to control so that none of the thermometers exceed 1125 ° C.

Therefore, in the invention of claim 6, a plurality of thermometers R-6, TC-5, TC-4, installed in the maximum temperature range,
The set value of the temperature controller in the maximum temperature range is raised or lowered by the thermometer showing the highest temperature of R-7. That is, the process temperature control is performed only by changing the temperature setting value of TC-4.
Select the maximum temperature of -6, TC-5, TC-4, R-7, and set the temperature setting value of TC-4 to + 1 ° C.
Alternatively, change it by -1 ° C to reach 1125 ° C. More specifically, thermometers R-6, TC-5, TC-4, R-7
If the highest temperature among them is 3 ℃ or more lower than 1125 ℃, TC
-4, the temperature setting value of TC-4 is increased by 1 ° C. Conversely, if the selected temperature is higher than 1125 ° C by 3 ° C or more, the temperature setting value of TC-4 is decreased by 1 ° C.

As a technique similar to this, the override control shown in FIG. 5 is known. This is a system in which the highest temperature among the thermometers R-6, TC-5, TC-4, and R-7 is selected, and the selected thermometer is used as the control amount of the controller. However, for example, when the maximum temperature is detected by the thermometer R-6 at the beginning of sending the vehicle, the thermometer R-6 on the inlet side is selected as the process temperature controller, so that the control response is not good. Remains. Claim 6
The invention has the advantage that this problem can be solved.

[Temperature Control in Slow Cooling Region] By carrying out the transportation in this way, the carriage heated to the maximum temperature in the firing region 4 is sent to the slow cooling region 7, and the temperature in the slow cooling region 7 gradually rises. However, in the slow cooling area 7, a blower F7 for driving the preheating furnace 8 and a blower F for exhausting the preheating furnace 8
8. Since the blowers F9 and F10 for heat recovery are provided, these blowers are controlled according to the temperature of the slow cooling zone 7,
The amount of air blown into the slow cooling region 7 or the amount of air exhausted from the slow cooling region 7 is changed according to the temperature. This makes it possible to reach a predetermined temperature curve in a short time.

[0023]

As described above in detail, according to the present invention, without waste of the intuition and experience of a skilled worker, there is no waste as in the case where an experienced tunnel furnace is operated by an expert. It can be automatically started up, and it can not only complete the temperature rise that took several days in the past in about 36 hours, but also take out the product loaded on the white background trolley as a good product at the start of the temperature rise. it can. Therefore, the present invention greatly contributes to the industry as an automatic temperature raising method for a tunnel furnace that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a plan view showing an entire tunnel furnace according to an embodiment of the present invention.

FIG. 2 is a sectional view of a portion on the outlet side of a soaking zone of a tunnel furnace.

FIG. 3 is a time chart showing the order of burner ignition in each zone of the firing area.

FIG. 4 is a graph showing changes in maximum temperature point.

FIG. 5 is a system diagram showing override control.

[Explanation of symbols]

1 furnace, 2a inlet, 2b outlet: 3 preheating zone: 4 firing zone, 5 soaking zone, 6 rapid cooling zone, 7 slow cooling zone, 8 preheating furnace, R-1 to R-17 thermometer, TC-1 to TC-5
Thermometer, F blower

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiro Kiriyama 2 116, Hojo, Tokoname City, Aichi Prefecture 2 (72) Inventor Takahiko Sanji 21 21, Miyamae, Kawaguchicho, Nishio City, Aichi Prefecture

Claims (7)

[Claims] 1. A tunnel furnace which is characterized in that, for a tunnel furnace in a dormant state, a burner and a blower are automatically started to form a furnace temperature necessary for firing, and a trolley is fed from an inlet. Automatic temperature raising method. 2. The automatic temperature raising method for a tunnel furnace according to claim 1, wherein cooling air is injected into the preheating zone to prevent an excessive temperature rise in the preheating zone during the temperature raising process. 3. The automatic temperature raising method for a tunnel furnace according to claim 1, wherein when the temperature in the preheating zone exceeds a preset value in the temperature raising process, the carriage is moved to suppress the temperature rise in the preheating zone. 4. The automatic temperature raising method for a tunnel furnace according to claim 1, wherein the operation / stop and speed of the carriage movement during or after the temperature rise is controlled according to the temperature inside the furnace. 5. The temperature controller is provided with a set value higher than the temperature in the furnace required for firing when the carriage is moved during or after the heating is completed, and this set value is required for firing by a predetermined calculation. The automatic temperature raising method for a tunnel furnace according to claim 1, wherein the temperature is raised to the temperature in the furnace. 6. The temperature controller in the maximum temperature range is moved up and down by a thermometer showing the highest temperature among a plurality of thermometers installed in the maximum temperature range, when the carriage moves while the temperature is rising. Item 2. The automatic temperature raising method for a tunnel furnace according to Item 1. 7. When raising the temperature of the slow cooling zone to a required temperature, the amount of air blown into the slow cooling zone or the amount of air exhausted from the cooling zone is changed according to the temperature of the slow cooling zone.
The method for automatically raising the temperature of a tunnel furnace according to.