JP5222502B2 - How to operate the rotary kiln - Google Patents

Description

  The present invention relates to a method for operating a rotary kiln used in a stoker-type incinerator that thermally incinerates an object to be treated such as general waste or industrial waste.

As an apparatus for efficiently incinerating general waste and industrial waste, an incinerator composed of a rotary kiln lined with furnace material and a stoker furnace provided downstream of the rotary kiln is used. This incinerator is combusted in the rotary kiln by the primary air supplied with waste, and the combustion residue from the rotary kiln is sent to the stoker furnace where the grate reciprocates back and forth and burns and is ashed. .
When operating an incinerator, it is necessary to maintain the furnace temperature optimally in consideration of various problems such as the degree of thermal decomposition of waste plastics, suppression of generation of harmful substances, and durability of the furnace wall. For example, when the residue at the kiln outlet becomes a predetermined temperature or lower, the grate heat load of the stoker furnace located downstream of the kiln increases, causing troubles such as melting of the grate. On the other hand, when the residue at the kiln outlet becomes a predetermined temperature or higher, the refractory material on the inner wall of the kiln furnace is significantly eroded by excessive combustion in the kiln, so the temperature in the furnace must always be suitably maintained. Thus, in order to smoothly operate the incinerator, temperature management in the furnace is an important requirement.

As for temperature measurement of a conventional melting furnace, as shown in Patent Document 1 (Japanese Patent Publication No. 4-68533), a method using a thermocouple thermometer is widely used.
In the technique provided in Patent Document 1, the temperature of each part in the rotary kiln is measured with a thermocouple, and the amount of recirculated gas is adjusted so that the temperature falls within a preset allowable range.

Japanese Examined Patent Publication No. 4-68533

However, in the invention disclosed in Patent Document 1, the number of thermocouples to be used is limited and many cannot be installed, so the temperature distribution in the furnace cannot be measured. Also, since it is in a corrosive environment, the thermocouple has a short life and its replacement is difficult.
Furthermore, even if the temperature inside the furnace is measured by a thermocouple and the amount of recirculation gas is adjusted so that the temperature falls within the preset allowable range, the workpiece at the furnace outlet and the state in the furnace are not known. The fire wall erosion due to the high temperature atmosphere in the furnace cannot be completely prevented. Measuring the temperature inside the furnace and monitoring the inside of the furnace are very important for proper operation of the furnace life and repair time.

  Therefore, in view of the above-mentioned problems of the prior art, the present invention detects the temperature distribution in the furnace and monitors the inside of the furnace, and adjusts the mixing ratio of the recirculation gas and air based on the state to efficiently treat the object to be processed. It aims at providing the operating method of the rotary kiln which burns.

Therefore, in order to solve such a problem, the present invention pyrolyzes the object to be processed in a rotary kiln, burns it in a stoker-type incinerator attached to the rotary kiln outlet side, and burns it in the stoker-type incinerator. In the operation method of the rotary kiln in which recirculated gas (hereinafter referred to as EGR gas) is refluxed and introduced into the workpiece input side of the rotary kiln and air is introduced into the workpiece input side of the rotary kiln.
The mixing ratio of the EGR gas and air is adjusted to control the flame generation position to a position in the range of 1/3 to 2/3 from the rotary kiln workpiece input side, and to the workpiece input side of the rotary kiln A visible camera is provided to detect the position where the flame is generated, and the amount of air is increased or decreased depending on the position where the flame is generated .

  According to the present invention, when the amount of air is increased, the flame generation position moves to the workpiece input side of the rotary kiln. In this way, by adjusting the mixing ratio of the EGR gas and air and controlling the flame generation position to a position in the range of 1/3 to 2/3 from the input side, the waste quality of the object to be processed can be improved. Occurrence of poor combustion due to fluctuations can be prevented, and soot and NOx can be reduced. Note that a constant amount of EGR gas is introduced, and the mixing ratio is adjusted by changing the amount of air. EGR gas is also effective in preventing bag fire because air alone ignites and the flame flows back to the rotary kiln input side.

Further , since the position where the flame is generated can be monitored while operating the rotary kiln, the position where the flame is generated can be adjusted as appropriate by increasing or decreasing the amount of air. In addition, by providing a visible camera on the rotary kiln input side, it is possible to monitor the ignition point even if the waste quality and the transfer speed of the input workpiece are uncertain.

In addition, when the soot is generated on the workpiece input side of the rotary kiln and the visibility of the visible camera is lowered, the amount of air is decreased to move the flame generation position away from the workpiece input side. To do.
As a result, it is possible to continue to monitor the flame occurrence position without degrading the visibility of the visible camera.

Furthermore, a temperature distribution detection device for detecting the furnace temperature range of the rotary kiln is installed on the outlet side of the rotary kiln, and the EGR gas is adjusted so that the thermal decomposition temperature detected by the temperature distribution detection device is 500 ± 50 ° C. And adjusting the mixing ratio of air.
In this way, by setting the thermal decomposition temperature to 500 ± 50 ° C., it is possible to gasify the polymer waste contained in the object to be processed without overcombustion. Therefore, it becomes possible to supply an object to be processed to a stoker furnace in a state where calories are reduced.

Further, the temperature distribution detection device is a thermo viewer.
By using a thermoviewer as a temperature distribution detection device, it becomes possible to detect the temperature distribution in the furnace. Moreover, while detecting temperature, since the stirring condition of the to-be-processed object by the side of a rotary kiln exit can be monitored, the soundness of the lifter (weir) which is provided in the rotary kiln inner wall and stirs to-be-processed object can be judged, for example. it can. It is very important to confirm the soundness of the lifter to raise the temperature of the workpiece in the rotary kiln uniformly.

  In addition, a thermocouple is inserted from the outlet side of the rotary kiln to measure the surface temperature or residue temperature of the refractory on the inner wall of the rotary kiln, and the pyrolysis temperature is detected together with the temperature distribution detector. Thereby, even when the emissivity changes depending on the quality of the object to be processed, it can be periodically calibrated with a thermocouple.

As described above, according to the present invention, by adjusting the mixing ratio of the EGR gas and air and controlling the flame generation position to a position in the range of 1/3 to 2/3 from the input side, It is possible to prevent the occurrence of defective combustion due to fluctuations in the quality of waste, and soot and NOx can be reduced.
In addition, since the position where the flame is generated can be monitored while the rotary kiln is operated, the position where the flame is generated can be adjusted as appropriate by increasing or decreasing the amount of air. Even if is uncertain, the ignition point can be monitored.
In addition, it is possible to continue monitoring the occurrence position of the flame without impairing the visibility of the visible camera.
Furthermore, by setting the thermal decomposition temperature to 500 ± 50 ° C., it is possible to gasify polymer waste contained in the object to be processed without overcombusting, and to reduce the number of calories in the object to be processed. It becomes possible to supply to the stoker furnace.
Furthermore, the temperature distribution in the furnace can be detected by using a thermo viewer as a temperature distribution detection device. Moreover, while detecting temperature, since the stirring condition of the to-be-processed object by the side of a rotary kiln exit can be monitored, the soundness of the lifter (weir) which is provided in the rotary kiln inner wall and stirs to-be-processed object can be judged, for example. it can. Moreover, even if the emissivity changes depending on the quality of the object to be processed, it can be periodically calibrated with a thermocouple.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
1 is a schematic view showing a processing apparatus equipped with a rotary kiln according to Example 1, FIG. 2 is a three-dimensional cross-sectional view of Example 1 (cross-sectional view taken along line AA in FIG. 1), and FIG. 3 is a test condition of Example 1. FIG. 4 is a schematic view showing a processing apparatus equipped with a rotary kiln according to the second embodiment.
In addition, the to-be-processed object used in a present Example uses the polymer wastes, such as a plastics, and the waste containing woody.

First, a rotary kiln operation method using the processing object processing apparatus of Example 1 will be described with reference to FIGS. 1, 2, and 3.
The processing apparatus shown in FIG. 1 is composed of a rotary kiln 1 and a stoker-type incinerator 2 attached to the rotary kiln outlet side. A refractory 12 is lined on the inner wall of the rotary kiln 1, and a plurality of lifters (not shown) projecting from the refractory 12 to the inside of the furnace are disposed on the inner periphery of the rotary kiln 1. Further, the rotary kiln 1 includes a charging hopper 3 for charging the workpiece 11, a visible camera 6 installed on the workpiece charging side (kiln inlet side), and a thermocouple 9 that can be inserted on the kiln outlet side as the other end. It consists of and.

Further, as other configurations, an EGR gas supply passage for returning EGR gas (recirculation gas) 4 extracted in the stoker type incinerator 2 to the rotary kiln 1, an air supply passage for supplying air 5, and an air amount are adjusted. And a fan 8 through which EGR gas 4 and air 5 pass. The air 5 used here is preferably adjusted so that the oxygen concentration is 21 to 40%. For this reason, although not shown, the processing apparatus of the present embodiment includes an oxygen supply device that supplies air and an oxygen concentration adjusting device that adjusts the oxygen amount so that the oxygen concentration becomes 21 to 40%.
The EGR gas 4 extracted by the stoker type incinerator 2 is supplied to the rotary kiln 1 after passing through a bag filter (not shown).

As a method of mixing the air 5 with the extracted EGR gas 4, a control mechanism may be provided before the rotary kiln is introduced, and it may be controlled automatically or manually. Alternatively, a duct or the like for passing a predetermined amount may be provided in advance. You may mix so that it may become the set mixing ratio.
FIG. 2 is a cross-sectional view (a cross-sectional view taken along line AA in FIG. 1) of the rotary kiln inlet side from the side, and an example of the arrangement of the mixed gas passage 21 of the EGR gas 4 and air 5 and the visible camera 6. It is shown schematically.

  In the first embodiment, the workpiece 11 is charged into the rotary kiln 1 from the charging hopper 3 and heated in the furnace to generate a flame 10. This flame 10 is a volatile gas (pyrolysis gas) of polymer waste such as plastic contained in an object to be treated, and can move both upstream and downstream in the rotary kiln 1 if there is a combustion source. The behavior of the flame 10 is monitored by the visible camera 6, and the EGR gas 4 and the air are set so that the generation position of the flame 10 is located in a range of 1/3 to 2/3 from the rotary kiln workpiece input side (inlet side). The mixing ratio of 5 is adjusted. At this time, if the air 5 is increased, the flame 10 moves to the inlet side of the rotary kiln 1, and if it decreases, the flame 10 moves to the outlet side. Here, the EGR gas 4 supplies a constant amount and varies only the air amount. The amount of the air 5 mixed with the EGR gas 4 by the damper 7 provided in front of the fan 8 is increased or decreased.

  In this way, the object 11 is thermally decomposed and transferred while being stirred by the lifter of the rotary kiln 1. At this time, since the surface temperature of the refractory 12 is detected by the thermocouple 9 inserted on the outlet side of the rotary kiln 1, it can be periodically calibrated even if the emissivity changes depending on the dust quality. It can be efficiently pyrolyzed. And the to-be-processed object 11 thermally decomposed is transferred to the stoker type incinerator 2, and burned.

Here, FIG. 3 shows the visibility of the visible camera when the position of the flame 10 is changed from the rotary kiln workpiece input side and the volatility result of the polymer waste contained in the workpiece 11. As shown in FIG. 3, it can be seen that the range of 1/3 to 2/3 from the workpiece input side of the rotary kiln is a range that satisfies both the visibility of the visible camera 6 and the volatility of dust.
If the flame 10 is too close to the rotary kiln workpiece input side, the charging hopper 3 becomes hot or the amount of soot and NOx increases. Moreover, since the to-be-processed object 11 will be heated too much with the flame of the stoker-type incinerator 2 if the flame 10 moves away from the rotary kiln to-be-processed object input side and is too close to the exit side, the to-be-processed object 11 will be stoker-type incinerator 2 May be burned before being transferred to

Thus, it is preferable to place the flame 10 in the range of 1/3 to 2/3 from the rotary kiln workpiece input side. For this purpose, the air amount is appropriately increased or decreased while monitoring by providing the visible camera 6.
In addition, the amount of air is increased / decreased depending on the ratio of the waste to be treated, the combustion state of the rotary kiln 1, and the soundness of the refractory 12. The amount of air plays an important role as an operating end for controlling the operation of the rotary kiln 1. Moreover, adjusting the rotation speed of the rotary kiln 1 in addition to the amount of air is preferably used as the operation end.

Therefore, according to Example 1, by adjusting the mixing ratio of the EGR gas and air and controlling the flame generation position to a position in the range of 1/3 to 2/3 from the rotary kiln charging side, the workpiece It is possible to prevent the occurrence of combustion failure due to fluctuations in the quality of soot and to reduce soot and NOx.
In addition, since the generation position of the flame 10 can be monitored by the visible camera 6 provided on the input side of the rotary kiln 1, the generation position of the flame 10 can be adjusted as appropriate by increasing or decreasing the air 5, and further input. The ignition point can be monitored even if the waste quality and transfer speed of the workpiece 11 are uncertain.
And in the range of 1/3 to 2/3 from the rotary kiln charging side preferable for the generation position of the flame 10, it is possible to continue monitoring the generation position of the flame without impairing the visibility of the visible camera 6, and It can be expected that the polymer waste contained in the object 11 is sufficiently volatilized.

First, the rotary kiln operation method using the processing apparatus of the workpiece of Example 2 is demonstrated using FIG. In the second embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.
The processing apparatus shown in FIG. 4 includes a rotary kiln 1 and a stoker-type incinerator 2 attached to the rotary kiln outlet side, as in the first embodiment. A refractory 12 is lined on the inner wall of the rotary kiln 1, and a plurality of lifters (not shown) projecting from the refractory 12 to the inside of the furnace are disposed on the inner periphery of the rotary kiln 1. Further, the rotary kiln 1 includes a charging hopper 3 for charging the workpiece 11, a visible camera 6 installed on the workpiece charging side (kiln inlet side), and a thermocouple 9 provided on the kiln outlet side as the other end. It consists of and. The thermocouple used here is not a consumable type.

In addition, an EGR gas supply passage for returning EGR gas (recirculation gas) 4 extracted in the stoker type incinerator 2 to the rotary kiln 1, an air supply passage for supplying air 5, and a damper 7 for adjusting the amount of air , The EGR gas 4 and the fan 8 through which the air 5 passes. The air 5 used here is preferably adjusted so that the oxygen concentration is 21 to 40%. For this reason, although not shown, the processing apparatus of the present embodiment includes an oxygen supply device that supplies air and an oxygen concentration adjusting device that adjusts the oxygen amount so that the oxygen concentration becomes 21 to 40%.
The EGR gas 4 extracted by the stoker type incinerator 2 is supplied to the rotary kiln 1 after passing through a bag filter (not shown).

  In addition to the above-described configuration, a thermo viewer 15 that detects the temperature range in the furnace of the rotary kiln 1 is installed on the outlet side of the rotary kiln 1 as a configuration different from the first embodiment. Since the outlet side of the rotary kiln 1 is less affected by soot and dust than the inlet side, it can be monitored stably. In addition, it is preferable that the wavelength of the thermo viewer 15 shall be 8-14 micrometers.

  In the second embodiment, the thermo viewer 15 is installed so as to monitor both the refractory 12 and the workpiece 11 on the inner wall of the kiln near the exit side of the rotary kiln 1. The surface temperature of the refractory 12 is suitable as a monitoring object because the emissivity change with time is small. In this way, the temperature range in the furnace of the rotary kiln can be detected. Then, the thermal decomposition temperature can be controlled efficiently by adjusting the mixing ratio of the EGR gas 4 and the air 5 according to the detected temperature range to control the thermal decomposition temperature. Here, the thermal decomposition temperature is preferably 500 ± 50 ° C. By setting the thermal decomposition temperature to 500 ± 50 ° C., it is possible to gasify the polymer waste contained in the object to be processed without overcombustion. Therefore, it becomes possible to supply an object to be processed to a stoker furnace in a state where calories are reduced.

Moreover, since both the refractory 12 and the to-be-processed object 11 of the kiln inner wall near the exit side of the rotary kiln 1 are monitored as mentioned above, not only the furnace temperature range is detected but also the to-be-processed object 11 is stirred. The situation can also be monitored. The soundness of the lifter that is provided on the inner wall of the rotary kiln and that stirs the object to be processed can be determined by the behavior of the object 11 to be processed.
If the lifter's soundness is impaired, the workpiece 11 in the rotary kiln 1 is not sufficiently stirred, and the temperature of the workpiece 11 is not uniform. Therefore, it is very important to confirm the soundness of the lifter in order to raise the temperature of the workpiece in the rotary kiln uniformly.

  Therefore, according to the second embodiment, in addition to the effects obtained in the first embodiment, the temperature in the furnace of the rotary kiln 1 can be detected by the thermo viewer 15 and the inside of the rotary kiln 1 can be monitored. Based on this, the mixing ratio of the EGR gas 4 and the air 5 can be adjusted to efficiently burn the workpiece 11.

  According to the present invention, the temperature distribution in the furnace is detected and the inside of the furnace is monitored, and the processing object can be burned by adjusting the mixing ratio of the recirculation gas and air based on the state. This is useful as a method of operating a rotary kiln that can efficiently process waste even if the waste quality or transfer speed fluctuates.

1 is a schematic view showing a processing apparatus including a rotary kiln according to Example 1. FIG. FIG. 3 is a three-dimensional cross-sectional view of the first embodiment (a cross-sectional view taken along line AA in FIG. 1). It is a figure which shows the test conditions of Example 1, and the result corresponding to it. 5 is a schematic view showing a processing apparatus including a rotary kiln according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Stoker type incinerator 3 Input hopper 4 EGR gas 5 Air 6 Visible camera 9 Thermocouple 12 Refractory material 15 Thermo viewer

Claims (5)

An object to be treated is pyrolyzed and gasified in a rotary kiln, burned in a stoker-type incinerator attached to the rotary kiln outlet side, and recirculated gas (hereinafter referred to as EGR gas) after combustion in the stoker-type incinerator In the operation method of the rotary kiln in which the air is introduced to the workpiece input side of the rotary kiln while being refluxed and introduced to the workpiece input side of the rotary kiln,
Adjusting the mixing ratio of the EGR gas and air to control the flame generation position to a position in the range of 1/3 to 2/3 from the rotary kiln workpiece input side ,
A method of operating a rotary kiln, comprising: providing a visible camera on a workpiece input side of the rotary kiln to detect a position where the flame is generated, and increasing or decreasing an amount of air depending on the position where the flame is generated . When the soot is generated on the workpiece input side of the rotary kiln and the visibility of the visible camera is lowered, the amount of air is decreased to move the flame generation position away from the workpiece input side. Item 10. A rotary kiln operation method according to item 1 . A temperature distribution detection device for detecting the furnace temperature range of the rotary kiln is installed on the outlet side of the rotary kiln, and the EGR gas and air are mixed so that the thermal decomposition temperature detected by the temperature distribution detection device becomes 500 ± 50 ° C. The operation method of the rotary kiln according to claim 1 or 2 , wherein a mixing ratio is adjusted. The operation method of the rotary kiln according to claim 3, wherein the temperature distribution detection device is a thermo viewer. Insert a thermocouple from the outlet side of the rotary kiln measuring the surface temperature or resid of the refractories of the rotary kiln inner wall, according to claim 3 or claim, characterized in that detecting the thermal decomposition temperature with the temperature distribution detection device Item 5. The operation method of the rotary kiln according to Item 4 .

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