JP2009275975A - Operating method of fluidized bed pyrolytic furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably operate a fluidized bed furnace by easily detecting deterioration of a bed material classifying device of a fluidized bed pyrolytic furnace. <P>SOLUTION: In this operating method of pyrolytic processing equipment comprising the pyrolytic furnace having a fluidized bed for fluidizing a bed material, a temperature measuring means for measuring a temperature of the fluidized bed, the bed material classifying device for classifying the bed material extracted from the pyrolytic furnace, and a bed material circulating passage for circulating the bed material classified by the bed material classifying device to the fluidized bed, temperature of several parts of the fluidized bed are measured by the temperature measuring means, temperature difference of the parts is calculated on the basis of the measured temperatures, and the deterioration of the bed material classifying device is detected while applying the temperature difference as a barometer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for operating a thermal decomposition treatment facility such as a gasification furnace having a fluidized bed.

  In recent years, the amount of heat generated from municipal waste has been increasing, and due to the problem of secondary pollution such as tightness of final disposal site capacity and groundwater contamination, and strengthening of laws and regulations, volume reduction and fixation by melting waste Is being promoted. Furthermore, there are many problems required for waste disposal such as suppression of fine pollutants such as dioxins.

Under such circumstances, waste is gasified (pyrolysis) in a reducing atmosphere in a gasification furnace as a pyrolysis furnace, the generated combustible gas is burned at a high temperature, and ash and gasification contained in the combustible gas A gasification melting process that melts the incineration residue discharged from the furnace attracts attention. This process has the following characteristics.
1. Using the energy of waste, ash can be melted, and the volume of incineration residue can be reduced and recycled.
2. Valuable metals can be recovered by low-temperature pyrolysis.
3. High-temperature incineration of the melting furnace can control fine harmful substances such as dioxins.

  There is a fluidized bed furnace type in the gasification melting treatment process, and sand is circulated and used as a fluidized medium.

For example, Patent Documents 1 and 2 disclose a technique in which sand that is a fluidized medium is taken out from a fluidized bed furnace together with incombustibles, classified by a fluidized medium classifier, and returned to the fluidized bed furnace.
JP-A-7-332614 JP 2003-74822 A

The fluid medium classifier uses screens, meshes, etc., but the fluid in the fluidized bed is a fluidized bed as a result of the metal on the screen being worn by the sand or incombustible material, etc. The particle size of the sand inside becomes large, and the sand flow state becomes unstable. For this reason, members such as screens are replaced regularly or when wear is confirmed.
Therefore, in order to check the wear of the screen, the operation of the fluid medium classifier is stopped during the operation of the gasifier and the screen opening is directly measured, but the screen wear is predicted without visual inspection. A way to do this is also considered. For example, as a method for predicting the abrasion of the screen, there is also a method of measuring the particle diameter by appropriately sampling the classified sand.
However, this method has a problem that it takes time to measure the particle size of the sand, and the change in the particle size described above does not appear in the sampling result depending on the sampling location.

  An object of the present invention is to provide a fluidized bed pyrolysis furnace operating method that easily detects deterioration of a fluidized medium classifier and realizes stable fluidized bed furnace operation.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research and found that when the fluid medium classifier deteriorates, temperature variation occurs in the fluidized bed (sand layer) of the pyrolysis furnace. It came to embody the operating method of the fluidized-bed pyrolysis furnace which concerns on invention.

  An operation method of a thermal decomposition treatment facility according to the present invention includes a thermal decomposition furnace having a fluidized bed for fluidizing a fluidized medium, temperature measuring means for measuring the temperature of the fluidized bed, and a fluid extracted from the thermal decomposition furnace. An operating method of a thermal decomposition treatment facility comprising a fluid medium classifier for classifying a medium and a fluid medium circulation path for circulating the fluid medium classified by the fluid medium classifier to the fluidized bed, the temperature Measuring the temperature at a plurality of locations of the fluidized bed with a measuring means, calculating a temperature difference at each location based on the measured temperature, and detecting deterioration of the fluidized medium classifier using this temperature difference as an index. And

  According to the present invention, it is possible to easily detect deterioration of a fluid medium classifier easily and at low cost. Therefore, timely maintenance management can be performed at a low cost. In addition, since the temperature is measured at multiple locations in the fluidized bed, it is less time-consuming and accurately detects changes in the particle size of the fluidized medium compared to sampling a part of the fluidized medium. There is an advantage that is easy to do.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 schematically shows a process flow of a waste treatment facility using a gasification melting furnace and an apparatus related thereto as an example of a waste pyrolysis treatment facility according to an embodiment of the present invention.

  As shown in FIG. 1, the waste A stored in the pit 1 is picked up by a crane, put into a hopper, crushed to an appropriate size, conveyed by a conveyor, and sequentially heated via a dust feeder 2. The fluidized bed type gasification furnace 3, which is a cracking furnace, is charged. The thrown-in waste is gasified in the fluidized bed 23 (fluidized bed) of the gasification furnace 3, and the combustible gasified is sent to the subsequent melting furnace 4 together with the ash, where the combustible is combusted, The ash is melted. The molten ash becomes molten slag and is discharged from the outlet at the bottom of the melting furnace.

  On the other hand, an incombustible material outlet is provided at the bottom of the fluidized bed 23 of the gasification furnace 3, and the incombustible material and sand as a fluid medium are discharged out of the furnace by the screw feeder 5. Sand and incombustible material discharged from the screw feeder 5 are separated by a sand classifier 6 (fluid medium classifier), and the sand under the sieve passes through a return line to a fluid sand return port by a sand circulation conveyor (not shown). It is carried back into the furnace. On the other hand, the incombustible material is discharged out of the system from the incombustible material discharge port of the sand classifier 6.

  Next, the sand classifier 6 will be described. The sand classifier 6 is a vibrating sieve provided with a screen having a constant mesh (sand passage interval). Referring to FIGS. 2 to 4, a receiving plate 13 is provided at the inlet of the sand classifier 6 so as to face the discharge duct at the outlet of the front end of the screw feeder 5, followed by the screen 8. It has been.

  In the present embodiment, the screen part 8 of the sand classifier 6 is arranged in parallel with a sand passage gap 17 having a width of 2 to 4 mm, for example, and arranged in a number orthogonal to the direction of sand flow. A screen plate 15 is provided. Each screen plate 15 is provided with a rearward downward inclined portion 16, and the inclined portion 16 of each screen plate 15 is positioned below the sand passage gap 17.

  When the operation is continued for a long time, the screen of the sand classifier 6 is worn by contact with sand, incombustibles, etc., and the opening is gradually widened. And when wear progresses, it will be replaced with a new screen plate.

  Next, a method for detecting deterioration of the fluid medium dispersion device according to the present embodiment will be described with reference to FIG. FIG. 5 is a schematic configuration diagram of a gasification furnace including a fluidized bed temperature detection means and a sand classifier deterioration detection means in the gasification furnace according to the present embodiment.

  As shown in FIG. 5, the gasification furnace according to the present embodiment includes a temperature measurement device (temperature measurement means) 21 and a calculator (sand classifier deterioration detection means) 22.

The temperature measuring devices 21 are installed at a plurality of locations on the fluidized bed 23 (two temperature measuring devices 21A and 21B in the figure), and measure the sand layer temperature (fluidized bed temperature) at a predetermined location on the fluidized bed 23 at regular intervals. In the case of a gasification furnace, the cycle of measuring the sand layer temperature by the temperature measuring device 21 may be the same as or different from the cycle of the control system. Here, it is preferable that one temperature measuring device 21 is installed in a place where dust is likely to stay when the fluidized air is reduced, and one or more temperature measuring devices 21 are installed in a place where the temperature is hardly transmitted from the place. For example, one is installed at a position where the waste is introduced (in the sand layer near the bottom of the waste input), and another is installed at a position far from the position. These locations may be changed according to the shape of the furnace, the location where the fluidized air is blown, the waste inlet, the amount of the fluid medium, and the like. Moreover, as another installation location of the temperature measuring device 21, a plurality of locations may be installed near the furnace wall and not in contact with the furnace wall, and further installed in the center of the furnace.
The temperature measuring device 21 uses a temperature measuring device using a thermocouple. The plurality of signals output from the plurality of temperature measuring devices 21 are input to the calculator 22 and used as temperature measurement values of the temperature of the fluidized bed 23 subjected to the plurality of signal processing.

  The computing unit 22 calculates a temperature difference from a plurality of temperature measurement values input from the temperature measuring device 21, and uses the calculated temperature difference at each location as an index to indicate the state of wear of the screen plate 15 of the sand classifier 6 (wear). The presence or absence or the degree thereof is detected, and an alarm is automatically issued when the temperature difference becomes a certain value, that is, a threshold value or more. It is preferable that the temperature difference threshold value for issuing an alarm is 5 to 10 ° C.

More specifically, when the wear of the screen plate 15 of the sand classifier 6 is shown, normally, sand and incombustibles extracted from the bottom of the fluidized bed are classified by a vibrating sieve, which is a sand classifier, and have a small particle size. The sand passes through the vibrating sieve and is collected at the lower part of the vibrating sieve and returned to the fluidized bed through the fluid medium circulation path. On the other hand, nonflammable materials and sand that has agglomerated and become larger in size remain on the sieve and are finally discharged out of the system. When the screen plate is not worn, only sand having a predetermined particle size is circulated. However, as the screen plate is worn, sand having a large particle size or incombustible material passes through the vibrating screen and is circulated to the fluidized bed. In the fluidized bed, when the sand having a predetermined particle size or less occupies most, the fluidity is good and the temperature in the fluidized bed is uniform. Here, when the screen plate is worn, the size of the sieve becomes large, so that the sand having a large particle size is mixed in the circulating sand. As the particle size increases, the flow state in the bed by the fluidized air also becomes non-uniform, resulting in variations in the temperature in the fluidized bed. Thereby, deterioration of the sand classifier can be detected, timely maintenance can be performed, and more stable operation of the pyrolysis furnace can be realized.
In the above embodiment, the pyrolysis furnace is a fluidized bed type gasification furnace, but may be a fluidized bed type incinerator.

(Example)
Using a fluidized bed gasification furnace as the pyrolysis furnace, the temperature of two fluidized bed locations in the gasification furnace (opposite positions 200 mm away from the furnace wall of the gasification furnace and 300 mm away from the furnace bottom) is continued with a thermocouple. And the wear of the screen plate of the sand classifier was confirmed. The initial sand passage gap (opening) of the screen portion 8 of the sand classifier 6 was 3 mm.
As a result, when there is no temperature difference (specifically, each temperature difference is less than 5 ° C), the screen wear was acceptable, but when the sand layer temperature difference became 10 ° C, the screen As shown in FIG. 6, it was confirmed that the screen opening was partially enlarged as shown in FIG.
Furthermore, when the particle size of the sand that passed through the screens at those times was measured, the ratio of the sand particle size of 3 mm or more was less than 5% when there was no difference in the sand layer temperature. When the difference in temperature reaches 10 ° C., the ratio of the sand particle size of 3 mm or more is 10% or more, and it can be confirmed that the ratio of the large particle size is increased and the particle size distribution is widened. It was.
After confirming the wear of the screen, as a result of replacing it with a new screen, the temperature difference between the two fluidized beds disappeared, and the particle size of the sand that passed through the screen became the same as the time when there was no difference in the temperature of the sand layer. .
Therefore, it is preferable that the temperature difference threshold value for issuing an alarm is 5 to 10 ° C.

  As is apparent from the results of the examples, according to the operation method of the waste pyrolysis equipment according to the invention, it is possible to easily detect the deterioration of the fluid medium classifier simply by measuring the temperatures at a plurality of locations in the fluidized bed. it can. Therefore, timely maintenance management can be performed at a low cost.

In the description of the embodiments and examples, the temperature difference at each location is calculated by the calculator 22 from a plurality of temperature measurement values input from the temperature measurement device 21, and the calculated value is a constant value (threshold value). At this point, it was judged that the classification screen had deteriorated, but the temperature in the fluidized bed (sand layer) temporarily changed at each location due to other factors not directly related to the deterioration of the classification screen. As a result, depending on the temperature measurement timing, the calculated value of the temperature difference may be temporarily increased to be equal to or greater than the threshold value.
Accordingly, in order to eliminate such error information, for example, (1) when the temperature measurement values at each location where the temperature difference is equal to or greater than the threshold value continues multiple times, (2) the average value of the temperature measurement values at each location for a certain period When the temperature difference becomes greater than or equal to the threshold value, (3) When the average value of the difference between the temperature measurement values in a certain period at each location is equal to or greater than the threshold value, or when the condition is satisfied It is also useful to set an alarm so that the classification screen is deteriorated, and these forms are also within the scope of the technical idea of the present application.
Further, in the description of the embodiment and examples, a gasification furnace is used as a fluidized bed type pyrolysis furnace, but not only a gasification furnace but also a fluidized bed type incinerator is within the scope of the technical idea of the present application. .

It is a schematic diagram which shows the outline | summary of the apparatus which concerns on the thermal decomposition equipment of the waste which concerns on this embodiment. It is an enlarged plan view of a fluid medium classification device. It is an expanded sectional view of a fluid medium classification device. It is a principal part expanded sectional view of FIG. It is a schematic block diagram of a gasification furnace provided with the temperature detection means and the sand classifier deterioration detection means of the fluidized bed in the gasification furnace which concerns on this embodiment. It is a top view which shows the visual result of the screen of a sand classifier at the time of the difference of sand layer temperature becoming 10 degreeC.

Explanation of symbols

3: Gasification furnace (pyrolysis furnace) 6: Sand classifier (fluid medium classifier)
8: Screen part 21: Temperature measuring device (temperature measuring means)
22: Calculator (sand classifier deterioration detection means) 23: Fluidized bed (fluidized bed)

Claims (2)

A pyrolysis furnace having a fluidized bed for fluidizing the fluidized medium, temperature measuring means for measuring the temperature of the fluidized bed, a fluidized medium classifying device for classifying the fluidized medium extracted from the pyrolysis furnace, and An operation method of a thermal decomposition treatment facility provided with a fluid medium circulation path for circulating a fluid medium classified by a fluid medium classifier to the fluidized bed,
Measuring the temperature at a plurality of locations in the fluidized bed with the temperature measuring means, calculating a temperature difference at each location based on the measured temperature, and detecting deterioration of the fluidized medium classifier using this temperature difference as an index. A method for operating a fluidized bed pyrolysis furnace characterized by the above.   2. The method of operating a fluidized bed pyrolysis furnace according to claim 1, wherein the fluid medium classifier uses a screen, and the deterioration is caused by abrasion of the screen.

Images