JP2020148414A - Heating furnace and temperature measuring method of heated body - Google Patents

Abstract

To provide a heating furnace having a function of measuring average temperature of a heated body.SOLUTION: A heating furnace heats a heating object while agitating it, and carries out the heated body by a conveyer, and has an infrared thermography device measuring temperature of every position of an image displayed in one image by imaging the heated body under carrying-out by the conveyer, the conveyer and circumference of the conveyer, and an analyzer for analyzing a histogram of the temperature measuring results of the infrared thermography device. The analyzer is provided with a function of sorting a background temperature histogram of the conveyer imaged by the infrared thermography device, a diaphragm temperature histogram of the conveyer, a reflection temperature histogram from the heated body, and a temperature histogram of the heated body, and a function of acquiring an average temperature value from a real temperature histogram of the heated body and determining the average temperature as the average temperature of the heated body under carrying-out by the conveyer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heating furnace having a function of measuring the temperature of a heated body and a method for measuring the temperature of the heated body.

As described on pages 859-860 of Non-Patent Document 1, used aluminum cans are evaporated or decomposed in a rotary kiln (roasting furnace) for moisture removal, painting and coating removal. ..
Since fine aluminum has a risk of ignition at high temperatures, a roasting process is performed in a roasting furnace for steaming while suppressing the oxygen concentration.

Directly measuring the internal temperature of a roasting furnace is extremely difficult due to the adhesion of soot and foreign matter to the thermocouple, and since there is virtually no line-of-sight distance inside the roasting furnace, a radiation thermometer It is also difficult to measure with. Moreover, it is extremely difficult to measure the temperature of an object being heated in a roasting furnace.
However, it goes without saying that temperature control of the roasted body is an important key to the success or failure of roasting, and from the viewpoint of safety or suppression of oxide generation during melting in the subsequent process, roasting It is desired to develop a technique capable of measuring the temperature of a roasted body.

"Recycling of aluminum foil and aluminum cap": Technical note (recycling technology): Makoto Oga et al .: Applied Physics: Volume 70: No. 7: P859-860 (2001)

In the roasting furnace, the aluminum cans after roasting are continuously discharged, and usually, there is almost no time when they are stationary, and they are conveyed to the melting furnace by a belt conveyor or the like. Further, since the used aluminum can discharged from the roasting furnace is usually thin and has a small heat capacity, it is difficult to measure the temperature by contact. Furthermore, even if you try to measure the temperature of a used aluminum can discharged from a roasting furnace by non-contact measurement such as a radiation thermometer, since non-contact measurement is a temperature measurement method using radiation, the measurement position and measurement angle If the above conditions are not constant, the morphological coefficient changes significantly, making stable temperature measurement difficult.

The present invention has been made in view of these problems, and provides a technique capable of measuring the temperature of a moving heated body such as a used aluminum can discharged from a heating furnace such as a roasting furnace. The purpose is to do.

The heating furnace of the present invention is a heating furnace that heats an object to be heated while stirring and carries out the heated body continuously or intermittently by a conveyor provided with a diaphragm, and is in the process of being carried out by the conveyor. An infrared thermography device that measures the temperature of each position displayed in the image by putting the heated body, the conveyor, and the periphery of the conveyor in one image, and an analysis device that analyzes the histogram of the temperature measurement result of the infrared thermography device. The analysis device includes a background temperature histogram of the conveyor imaged by the infrared thermography device, a vibrating plate temperature histogram of the conveyor, a reflection temperature histogram from the heated body, and an actual temperature of the heated body. It is characterized by having a function of dividing a histogram and a function of obtaining an average temperature value from the actual temperature histogram of the heated body and determining the average value as the average temperature of the heated body being conveyed by the conveyor. To do.

In the heating furnace of the present invention, when the reflected temperature histogram from the heated body and the actual temperature histogram of the heated body are separated, the peak curve centered on the highest temperature of the reflected temperature histogram and the actual temperature It is preferable to have a function of defining the lowest temperature appearing in the region where the peak curves centered on the highest temperature in the histogram intersect as the boundary between the reflected temperature histogram and the actual temperature histogram.
In the heating furnace of the present invention, it is preferable that the infrared thermography apparatus has a function of setting an emissivity.
In the heating furnace of the present invention, it is possible to provide a used aluminum can as the heating element.

The method for measuring the temperature of a heated body according to the present invention is applied to a heating furnace in which the heated body is heated while stirring and the heated body is continuously or intermittently carried out by a conveyor equipped with a diaphragm. This is a method of measuring the average temperature of the heated body carried out from the heating furnace, in which the heated body being carried out by the conveyor, the conveyor, and the periphery of the conveyor are stored in one image and displayed in the image. The temperature of each position is measured by an infrared thermography device, a histogram of the temperature measurement result of the infrared thermography device is collected, the background temperature histogram of the conveyor imaged by the infrared thermography device, the vibrating plate temperature histogram of the conveyor, and the like. The reflected temperature histogram from the heated body and the temperature histogram of the heated body are separated, the average value of the temperature is obtained from the actual temperature histogram of the heated body, and the average value is heated during transportation by the conveyor. It is characterized by judging that it is the average temperature of the body.

In the method for measuring the temperature of a heated body according to the present invention, when the reflected temperature histogram from the heated body and the actual temperature histogram of the heated body are separated, the maximum temperature of the reflected temperature histogram is the center. It is preferable to define the lowest temperature that appears in the region where the peak curve and the peak curve centered on the highest temperature of the actual temperature histogram intersect as the boundary between the reflected temperature histogram and the actual temperature histogram.
In the method for measuring the temperature of a heated body according to the present invention, it is preferable that the infrared thermography apparatus has a function of setting an emissivity.
In the method for measuring the temperature of a heated body according to the present invention, it is preferable that the heated body is a used aluminum can.

INDUSTRIAL APPLICABILITY According to the present invention, the average temperature of a heated body that is vibrated by a conveyor and carried out in an amorphous state from a heating furnace such as a roasting furnace can be measured more accurately than a conventional method.
Therefore, the temperature control of the heating furnace for heating the heated body can be controlled in more detail than before, so that the heated body can be heated to a target temperature range more reliably than before.
Therefore, when the heated body is, for example, a used aluminum can, by accurately heating the used aluminum can to a target temperature, moisture removal, coating film removal, and coating removal on the surface of the aluminum can are ensured. become able to.

Explanatory drawing which shows an example of the aluminum can recycling process using a roasting furnace. The perspective view which shows an example of the heated body which is conveyed from a roasting furnace by a belt conveyor. The graph which shows an example of the result of having measured the temperature histogram about the roasted body in the process of transportation shown in FIG. The figure which shows an example of the result of having measured the temperature with an infrared thermography apparatus about the heated body in the process of transporting from a roasting furnace. In the temperature histogram shown in FIG. 3, a graph showing the results of obtaining frequency distributions for the background temperature and the diaphragm temperature. In the temperature histogram shown in FIG. 3, a graph for explaining a method of averaging temperatures in a temperature region higher than the temperature of the diaphragm. A graph showing the result of finding the relationship between time and maximum temperature for a heated body being transported from a roasting furnace. It is a graph which shows the result of temperature analysis which applied the technique which concerns on this invention about the heated body which is being transported from a roasting furnace, (A) is the result of measurement in the first half of a specific time zone, (B) is A graph showing the results measured in the latter half of a specific time zone. A graph showing the results of finding the relationship between time and average temperature for a heated body being transported from a roasting furnace.

Hereinafter, the first embodiment of the heating furnace according to the present invention will be described in detail with reference to the accompanying drawings.
In the drawings used in the following description, in order to make the features easier to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. Absent.
The collection / regeneration facility shown in FIG. 1 is provided with a receiving facility 1 that accepts collected materials mainly composed of lumpy used aluminum cans that have been brought in by a transport means such as a truck. Further, the recovery / regeneration facility includes a crusher (breaker) 2 for crushing the recovered material, a sorting means 3 for separating the non-aluminum material from the recovered material crushed by the crusher 2 by using magnetic force and wind force, and the sorting means 3. It is provided with a rotary kiln (heating furnace: roasting furnace) 4 for roasting an aluminum can (heated body) that has passed through the sorting means 3.
The sorting means 3 includes a magnetic sorting machine 3a and a wind power sorting machine 3b, and an aluminum can is conveyed to the rotary kiln 4 via the primary stock hopper 11. Belt conveyors 10a to 10d are provided between each facility from the crusher 2 to the rotary kiln 4, and aluminum cans processed by each facility are conveyed.
Further, the recovery / regeneration equipment includes a melting furnace 5 for melting and processing the aluminum can discharged from the rotary kiln 4, a holding furnace 6 for holding the aluminum obtained in the melting furnace 5 in a melted state and adjusting an alloy, and holding the same. The furnace 6 is roughly configured with a casting machine 7 for obtaining slabs from alloy-adjusted molten metal, and devices including these are arranged in the same site 8.
A vibrating sieve 12 is disposed on the downstream side of the rotary kiln 4 via a belt conveyor 10e, and an aluminum can passing through the vibrating sieve 12 is introduced into the melting furnace 5 by the belt conveyor 10f. A storage furnace 14 is provided on the discharge side of the melting furnace 5 via a trough 13, and the discharge side of the storage furnace 14 is connected to the input side of the holding furnace 6 by a trough 15a.

In the recovery / regeneration facility shown in FIG. 1, the rotary kiln (heating furnace: roasting furnace) 4 has a stirring device (not shown) for stirring used aluminum cans (heated body) inside, and is heated and roasted to a target temperature. The vibrating sieve 12 is provided via a conveyor 10e that continuously or intermittently carries out a mass of baked aluminum cans (heated body). Then, an infrared thermography apparatus 20 described below is installed in the vicinity of the vibrating sieve 12, for example, diagonally upward.

The infrared thermography device 20 includes an infrared image sensor 21 and a device main body 22, and the device main body 22 is connected to a data analysis device 23 including a personal computer or the like.
When the infrared image sensor 21 detects the infrared radiant energy radiated from an object, the device main body 22 is a device that converts the received light amount of each pixel into an image as a temperature distribution and displays it.
As an example, the infrared image sensor 21 and the apparatus main body 22 can apply the infrared thermography FSV-2000 manufactured by Apiste.

FIG. 2 shows an outline of a mass 25 of aluminum cans being conveyed by the vibrating sieve 12.
The aluminum can mass 25 discharged from the rotary kiln 4 is an amorphous one in which a plurality of crushed aluminum cans are integrated into a mass, and has a temperature distribution as shown by shades of gray in FIG. There is. Further, the vibrating sieve 12 constantly vibrates and conveys the aluminum can mass 25 by the diaphragm at a high speed, for example, at a speed of several m / sec, and the shape and amount of the aluminum can mass 25 discharged from the rotary kiln 4 are changed from moment to moment. Change. In the present embodiment, the temperature of the lump 25 of the amorphous aluminum can that vibrates and moves is used as the object of temperature measurement.

If the internal temperature of the rotary kiln 4 is too high, a part of the aluminum can mass 25 may burn, and if the temperature is too low, it will be in a steamed state, and the coating and coating removal will be insufficient, and in some cases, the aluminum can mass Dross (impurities) that are discharged while adhering to 25 and melted coatings and coatings increase.

FIG. 4 shows an example of an image drawn on the display screen of the data analysis device 23. The aluminum can mass 25 shown in FIG. 2 shows a state in which an actual aluminum can mass 25 on the vibrating sieve 12 of the display image shown in FIG. 4 is modeled. In FIG. 2, a dark portion on the vibrating sieve 12 indicates a high temperature portion, and a light colored portion indicates a low temperature region.
The dark portions on the left and right of the vibrating sieve 12 shown in FIG. 4 indicate the space and the portion of the metal fitting that supports the vibrating sieve 12, and the dark portion provided above the vibrating sieve 12 is a support member that supports the conveyor 10e. Therefore, the temperature of these parts is displayed as a low temperature.

The vertically elongated bar with the numerical value shown on the right side of FIG. 4 is a display area indicating the temperature. In the example of FIG. 4, 35.0 ° C., 92.3 ° C., 149.7 ° C., 207.0 ° C., 264 Temperature scales of .4 ° C, 321.7 ° C, 379.1 ° C and 436.4 ° C are engraved.
The actual image shown in FIG. 4 is a color image, which is dark blue around 35.0 ° C, bright blue around 92.3 ° C, green around 149.7 ° C, yellow around 207.0 ° C, and 264. Around .4 ° C is displayed in orange, around 321.7 ° C is displayed in red, around 379.1 ° C is displayed in pink, and around 436.4 ° C is displayed in light pink. The vibrating sieve 12 displayed in the center of the screen and the inside thereof. The lumps of aluminum cans are also color-coded according to temperature.

FIG. 2 is a schematic view of the heated body during transportation shown in FIG. 4, and since the only colors that can be used in FIG. 2 are white, black, and gray, the display for each color is completely related. However, as an outline, the region indicated by reference numeral 25A is the maximum temperature range of about 379.1 ° C. to 436.4 ° C., the region indicated by reference numeral 25B is the temperature range of about 321.7 ° C., and the region indicated by reference numeral 25C is. The temperature range of about 149.7 ° C. to 207.0 ° C., the inner side wall of the vibrating sieve 12 is the temperature range of about 92.3 ° C., and the outer region of the vibrating sieve 12 is the temperature range of about 35.0 ° C. The image is color-coded.

As described above, the vibrating sieve 12 constantly vibrates, the aluminum can lump 25 is conveyed at a speed of several m / sec, and the shape and amount of the aluminum can lump 25 change from moment to moment.
Therefore, it is necessary to extract and specify the temperature of only the aluminum can mass 25 from the image shown in FIG. 4 by some means.
In the present embodiment, the apparatus main body 22 of the infrared thermography apparatus 20 sets a rectangular region, a polygonal region, an elliptical region, and the like from the images shown in FIG. 4, and measures the minimum temperature, the maximum temperature, and the average temperature for each region. Make use of the fact that it is possible and that the emissivity can be set.

First, the temperature measurement target region of the infrared thermography apparatus 20 is set inside the vibrating sieve 12. The vibrating sieve 12 is provided with a diaphragm inside a gutter-shaped transport path main body 12a, and the diaphragm transports a mass 25 of aluminum cans. The inside of the vibrating sieve 12 is the inner surface side of the gutter-shaped transport path main body 12a. For the emissivity, 0.8 was selected in this example.

The image shown in FIG. 4 of the region set by the infrared thermography apparatus 20 is imaged at a ratio of 1 sheet / 0.25 sec for a required time, and a temperature histogram as shown in FIG. 3 of the set region is collected.
In the temperature histogram shown in FIG. 3, the horizontal axis indicates the temperature (° C.), and the vertical axis indicates the frequency (frequency at which pixels of the corresponding temperature appear on the image). In this temperature histogram, it can be determined that the region from 50 to 100 ° C. is the region where the background temperature of the vibrating sieve 12 is low.
Similarly, the region of 100 to 200 ° C. is determined to be the temperature region of the vibrating sieve 12, the region of 200 to 350 ° C. is determined to be the reflection temperature detection region by heat reflection or the like, and the region of 400 ° C. to 550 ° C. is the aluminum can. It can be determined that it is in the actual temperature range of the mass (UBC) 25.

Such a judgment can be made because when the irregularly shaped aluminum can lumps 25 move intermittently along the vibrating sieve 12, the background and the area of the diaphragm hardly change. This is because it can be clearly distinguished as having two peaks in each temperature range as shown in.
Next, regarding the determination of the temperature range higher than these, as shown in FIG. 6, the reflected temperature histogram from the aluminum can mass 25 and the actual temperature histogram of the aluminum can mass 25 have two bumps having two peaks. If it is a type, it is easy to distinguish.

However, it is uncertain whether or not the two-humped type will be formed depending on the timing of measurement by the infrared thermography device 20 and the amount of transport of the aluminum can block 25. Therefore, in the high temperature region including the reflection temperature histogram from the aluminum can block 25 and the actual temperature histogram of the aluminum can block 25, the average is taken.

Of course, when the two-hump type peak shown in FIG. 6 appears, the lower one is recognized as the temperature due to heat reflection, the lowest temperature region in the boundary region of both peaks is defined as the boundary, and the higher histogram is used. Can be used as the actual temperature histogram of the mass 25 of the aluminum can, and even if the number of bumps does not reach 2, the pixels of 400 ° C. or higher may be used as the actual temperature histogram.
In the example of FIG. 3, when it is determined in this way, it can be determined that the histogram in the temperature region of 400 ° C. or higher is the actual temperature histogram of the aluminum can block 25.

In the case of the temperature histogram shown in FIG. 3, to take the average means to extract only the pixels of 400 ° C. or higher and take the average of the temperatures on the premise that the temperature becomes 2 bumps. In the present embodiment, even if an image that does not have two bumps appears, the average of the pixels of only 400 ° C. or higher is taken.

The temperature histogram shown in FIG. 3 shows the measurement result for 30 minutes carried out from the actual roasting furnace. FIG. 3 is temperature histogram data obtained as a result of processing about 10,000 images with one image as one image / 0.25 sec.
On the other hand, FIG. 7 shows the results of measuring the displacement of the observed maximum temperature in an arbitrary measurement time zone for the aluminum can mass 25 carried out from the actual roasting furnace. The time average is 200 sections (200 x 0.25 seconds = 50 seconds).

When a used aluminum can with a large amount of water was put into the roasting furnace in the state shown in FIG. 7 at the beginning of the measurement time, the maximum observed temperature tended to decrease, and as a result, the control temperature of the roasting furnace was raised. Temperature changes are shown.
As shown in FIG. 7, the temperature of the aluminum can mass 25 can be correlated to some extent, but the analysis from the results shown in FIG. 7 does not make it easy to grasp the temperature of the aluminum can mass 25.

On the other hand, in FIG. 8, it is determined from the analysis of the temperature histogram shown in FIG. 3 that the temperature range of 400 ° C. or higher corresponds to the actual temperature range of the mass 25 of the aluminum can, and the temperature fluctuates only for the components of 400 ° C. or higher in the temperature histogram. And the average of the temperature is calculated and displayed. FIG. 8 is a graph flattened on an average of 2.5 seconds, which can be easily grasped as a temperature display.
Using the graph shown in FIG. 8, the temperature fluctuation range was 60 ° C. as shown in FIG. 7, whereas the temperature fluctuation range was 15 ° C., which could be significantly suppressed. Using the results shown in FIG. 8, it can be seen that the tendency of the temperature decrease and the temperature increase of the aluminum can lump 25 carried out from the roasting furnace can be surely grasped at about 10 ° C.

The graph shown in FIG. 8 is an image display of the temperature histogram data sent by the apparatus main body 22 of the infrared thermography apparatus 20 to the data analysis apparatus 23 composed of a personal computer as a result of analysis by the data analysis apparatus 23. When a display device such as a display is connected to the data analysis device 23, the graph shown in FIG. 8 can be displayed as an image on the display device and visually confirmed.
The images shown in FIG. 8 may be sequentially displayed on the display device of the data analyzer 23, and the operator who visually confirms the temperature transition may manually fine-tune the temperature control of the rotary kiln 4, or the image shown in FIG. Even if the data analyzer 23 is equipped with a function to automatically adjust the temperature of the rotary kiln 4 so that the temperature change is automatically canceled when the average temperature changes beyond 10 ° C., the temperature of the rotary kiln 4 is controlled. good. Alternatively, the threshold value in the control may be set to a temperature lower than 10 ° C., and the data analyzer 23 may sequentially control the temperature.

FIG. 9 shows the results of measuring the relationship between the observed average temperatures in an arbitrary measurement time zone for the aluminum can lumps 25 carried out from the actual roasting furnace. The time average is 200 sections (200 x 0.25 seconds = 50 seconds).
In the state shown in FIG. 9, the fluctuation range of the temperature change tendency became larger than that of the temperature shown in FIG. 7.
Therefore, even if the relationship between the maximum temperature or the average temperature shown in FIGS. 7 and 9 is used, it is considered difficult to grasp the tendency of the temperature fluctuation of the aluminum can mass 25.

On the other hand, if it is the average of the temperature histograms of 400 ° C. or higher as shown in FIG. 8, it can be seen that the tendency of temperature decrease and the tendency of temperature increase can be easily grasped. For example, as shown in FIG. 8, it can be easily grasped that a fluctuation of 10 ° C. level occurs on the scale on the vertical axis, and roasting is performed by adjusting the temperature setting value of the roasting furnace so as to cancel this temperature change. It will be possible to control the temperature control of the furnace more strictly than the conventional technology.

4 ... Rotary kiln (heating furnace: roasting furnace), 12 ... Vibration sieve,
20 ... Infrared thermography device, 21 ... Infrared image sensor, 22 ... Device body,
23 ... Data analysis device.

Claims (8)

A heating furnace in which the heated body is heated while stirring, and the heated body after heating is continuously or intermittently carried out by a conveyor equipped with a diaphragm. The heated body being carried out by the conveyor and the conveyor. The analyzer is provided with an infrared thermography device that measures the temperature of each position displayed on the image by putting the area around the conveyor in one image, and an analysis device that analyzes a histogram of the temperature measurement result of the infrared thermography device. , The function of separating the background temperature histogram of the conveyor imaged by the infrared thermography apparatus, the vibrating plate temperature histogram of the conveyor, the reflected temperature histogram from the heated body, and the temperature histogram of the heated body, and the above. A heating furnace having a function of obtaining an average temperature from an actual temperature histogram of a heated body and determining the average value as the average temperature of the heated body being transported by the conveyor. When the reflection temperature histogram from the heated body and the actual temperature histogram of the heated body are separated, the peak curve centered on the maximum temperature in the reflected temperature histogram and the maximum temperature in the actual temperature histogram are used. The heating furnace according to claim 1, further comprising a function of defining the lowest temperature appearing in the region where the central peak curves intersect as the boundary between the reflected temperature histogram and the actual temperature histogram. The heating furnace according to claim 1 or 2, wherein the infrared thermography apparatus has a function of setting a radiance rate. The heating furnace according to any one of claims 1 to 3, wherein the heating element is a used aluminum can. The heated body is heated while stirring, and the heated body after heating is applied to a heating furnace that is continuously or intermittently carried out by a conveyor equipped with a diaphragm, and the average of the heated bodies carried out from the heating furnace. It ’s a method of measuring temperature.
The heated body being carried out by the conveyor, the conveyor, and the surroundings of the conveyor are stored in one image, the temperature at each position displayed on the image is measured by the infrared thermography device, and the temperature measurement result of the infrared thermography device is histogramd. The background temperature histogram of the conveyor imaged by the infrared thermography apparatus, the vibrating plate temperature histogram of the conveyor, the reflected temperature histogram from the heated body, and the actual temperature histogram of the heated body are separated. A method for measuring the temperature of a heated body, which comprises obtaining an average temperature from the actual temperature histogram of the heated body and determining the average value as the average temperature of the heated body being conveyed by the conveyor. When the reflection temperature histogram from the heated body and the actual temperature histogram of the heated body are separated, the peak curve centered on the maximum temperature in the reflected temperature histogram and the maximum temperature in the actual temperature histogram are used. The method for measuring the temperature of a heated body according to claim 5, wherein the lowest temperature appearing in the region where the peak curves at the center intersect is defined as the boundary between the reflected temperature histogram and the actual temperature histogram. The method for measuring the temperature of a heated body according to claim 5 or 6, wherein the infrared thermography apparatus has an emissivity setting function. The method for measuring the temperature of a heated body according to any one of claims 5 to 7, wherein the heated body is a used aluminum can.