JP2003247706A - Method and apparatus for burning organic waste - Google Patents

Abstract

(57) The Abstract: organic waste during burning by the oxidation catalyst, to prevent the occurrence of NO _X. SOLUTION: An area in which a fluidized bed 2 for thermally decomposing organic waste is formed, and a gas transfer path 13 through which a pyrolysis gas 8 generated by the pyrolysis moves, are provided in the gas transfer path 13. Means 15 for decomposing ammonia in the gas and oxidizing catalyst 9 having oxidizing performance are arranged along the flow direction. [Effect] Catalytic combustion treatment of organic waste without generation of nitrogen oxides due to oxidation of ammonia can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to combustion / incineration treatment of organic waste.

[0002]

2. Description of the Related Art Conventionally, a combustion method and a combustion apparatus for treating organic waste by oxidative decomposition with an oxidation catalyst are known. As the device, a combustion device previously proposed by the present inventors will be described with reference to FIG. In the figure,
1 is a waste supply port, 2 is a fluidized bed, 3 is a dispersion plate for supporting the fluidized bed 2 and allowing air to pass therethrough, 4 is a heating means for initially heating the fluidized bed 2, and 5 is air supplied to the fluidized bed 2. An air transporter, 6 a gasification furnace, 7 a fluid medium, 8 a pyrolysis gas generated by thermally decomposing waste, 9 an oxidizing catalyst, 10 air sent from the air transporter 5, 11
Is air heated by the oxidizing catalyst 9 and sent to the fluidized bed 2.

Next, the operation of the above device will be described. When the waste is introduced from the waste supply port 1 into the gasification furnace 6 which has been heated by the heating means 4 in advance, the waste is crushed and heated by the fluidized medium 7 to generate the pyrolysis gas 8. , The pyrolysis gas is oxidized (combusted) by the oxidizing catalyst 9.
To be done. The air 10 sent from the air transporter 5 is heated by the heat generated at this time, and the gasification furnace 6 partitioned by the dispersion plate 3 is heated and held by the heated air 11 and the heating means 4 is used during steady operation. Instead, the waste will continue to be heated and decomposed.

[0004]

However, since the conventional thermal decomposition apparatus utilizing catalytic combustion is constructed as described above, the thermal decomposition gas is directly oxidized into the oxidation catalyst and oxidized. At this time, most components of the pyrolysis gas are oxidized in the high temperature range even though many components have different oxidation performances for each component of the catalyst, but when the pyrolysis gas contains ammonia, ammonia has a problem that occurs nitrogen oxides (NO _X) in the catalytic combustion of the high temperature zone.
FIG. 4 shows the decomposition performance of ammonia in a platinum-based oxidation catalyst which is one of the oxidation catalysts. It has been shown that the oxidation catalyst decomposes the ammonia component to generate high concentration of NO _X.

The present invention has been made in order to solve the problems of the above-mentioned conventional ones, and an organic substance that does not generate nitrogen oxides by removing ammonia contained in a pyrolysis gas and then catalytically burning it. It is an object of the present invention to provide a method and an apparatus for burning organic waste.

[0006]

In order to solve the above problems, among the methods for burning organic waste of the present invention, the invention according to claim 1 is the ammonia component in the pyrolysis gas generated by the organic waste. Is decomposed and removed, and then oxidatively decomposed by an oxidation catalyst.

The invention of a method for burning organic waste according to a second aspect is the invention according to the first aspect, wherein the organic waste is thermally decomposed in a fluidized bed to generate a thermally decomposed gas. The ammonia component in the thermal decomposition gas is decomposed and removed in the downstream region where the thermal decomposition gas moves, and the thermal decomposition gas is burned at a low temperature in the downstream region by a catalyst having an oxidizing performance.

The invention of the method for burning organic waste according to claim 3 is the invention according to claim 1 or 2, wherein air is heated by heat generated by combustion with a catalyst having an oxidizing performance, and the heating is performed. Air is introduced into the fluidized bed to maintain the fluidized bed at a high temperature.

The invention of the organic waste combustion apparatus according to claim 4 is characterized in that the ammonia component in the pyrolysis gas is decomposed and removed, and then oxidatively decomposed by an oxidation catalyst.

The invention of an organic waste combustion apparatus according to claim 5 is the invention according to claim 4, wherein a region in which a fluidized bed for thermally decomposing the waste is formed and thermal decomposition generated by the thermal decomposition are formed. A gas moving path through which the gas moves, and a means for decomposing ammonia in the pyrolysis gas and an oxidizing catalyst having oxidizing performance are arranged along the flow direction in the gas moving path. Characterize.

The invention of an organic waste combustor according to a sixth aspect is the invention according to the fourth or fifth aspect, in which air is heated by heat generated by low temperature combustion of the pyrolysis gas in the catalyst filter. And a heated air transfer path for transferring the air heated by the air heating section to the fluidized bed forming region.

That is, according to the present invention, after the ammonia in the pyrolysis gas is decomposed and removed, it is oxidatively decomposed by the oxidation catalyst, so that the pyrolysis gas is oxidatively decomposed and organic nitrogen is hardly generated by the ammonia. Capable of treating toxic waste.

In the method and apparatus of the present invention, wastes such as organic compounds are treated. However, the present invention is not limited to a specific object, and may be a waste that can be treated by the method and apparatus of the present invention. In the present invention, for example, the waste is thermally decomposed in a fluidized bed to generate a thermally decomposed gas. This fluidized bed is usually formed during operation in a space which is defined as a fluidized bed forming region allocated in the fluidized bed furnace,
In its formation, a fluid medium of an appropriate material is used. The fluidized medium in the present invention may be one that forms a fluidized bed mainly or as a whole function, and forms the fluidized bed assuming that low temperature combustion is completed in the conventional fluidized bed. Not something to do. Therefore, from the above viewpoint, the selection of the material of the fluidized medium, the particle size, the density, etc. may be determined.
As the material, for example, γ-alumina or silica sand having excellent fluidity can be used.

In the fluidized bed formed by the fluidized medium, waste is introduced through a waste supply unit provided in the fluidized bed furnace. This waste material is thermally decomposed in the fluidized bed to generate a thermally decomposed gas. In the method and apparatus of the present invention, for example, the pyrolysis gas is transferred from the fluidized bed to another part through the gas transfer path. This transfer may be a natural flow, or may be forcibly moved by a fan or the like. A means for decomposing the ammonia of the pyrolysis gas is provided in the gas moving path corresponding to the downstream region of the fluidized bed.

The means for decomposing ammonia placed immediately before the oxidation catalyst may be, for example, an ammonia oxidation decomposition catalyst. In this case, ammonia is oxidatively decomposed at almost 350 ° C. or higher with almost no emission of nitrogen oxides. Even if the pyrolysis gas is oxidized by the subsequent oxidation catalyst, the generation of nitrogen oxides by ammonia can be suppressed.

In order to burn the pyrolysis gas at a low temperature on the downstream side of the above means, a catalyst having an oxidizing performance is arranged. The catalyst is arranged so that the pyrolysis gas moving in the gas moving path is effectively brought into contact with the catalyst and burns at a low temperature. Normally,
This is done by placing a catalyst filter holding the catalyst in the gas transfer path. In the catalytic filter, the gas passes through and comes into contact with the catalyst, and the action of the catalyst causes an oxidation reaction of the pyrolysis gas, that is, low temperature combustion (for example, about 300 to 600 ° C.). The heat generated by the combustion is transferred to the air heater by a suitable method.

The air heater usually has the form of a heat exchanger, and the heat exchanger is provided with an air passage for moving the air, and the air is moved through the passage to exchange heat with the air. A structure for heating is exemplified. The method for receiving heat from the combustion heat is not particularly limited, and may be, for example, one in which the combustion gas heated to a high temperature by combustion is received by the air heater as a heat medium, and the combustion space in the catalyst filter is used. It may be one that receives heat through the wall portion of the above, or a combination thereof. In addition,
It is desirable to incorporate the catalyst filter in the heat exchanger,
An example is one in which a gas flow path independent of the air flow path is provided for heat exchange. By disposing the catalyst in this gas flow path, the pyrolysis gas and the catalyst come into contact with each other. The heat of the gas can be transferred to the above-mentioned air through an appropriate heat transfer section. A gas passage wall, an appropriate heat transfer member, a heat pipe, or the like can be used as the heat transfer section, and the present invention is not limited to a particular one.

The air heated by the air heater can be sent to the fluidized bed. The heated air can be transferred through an appropriate heated air transfer path. The air transfer path may have a structure that allows the air heater and the fluidized bed forming region to communicate with each other. The heated air may be transferred by using a natural flow or by forced transfer. If the air heater is arranged below the fluidized bed forming region and a heating air transfer path is provided between the air heater and the fluidized bed forming region, the heated air can be transferred in the shortest path, and heat loss can be reduced. The air can be easily transferred by utilizing the rising force of the heated air. The heated air delivered to the fluidized bed keeps the fluidized bed at a high temperature and allows the continuously input waste to be subsequently pyrolyzed without the need for external heating. Moreover, the thermal decomposition is carried out in a fluidized bed using a medium in which fluidity is important, and thereafter the catalyst is burned at a low temperature, so that the reaction efficiency of these is greatly improved.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. Note that, in this embodiment, the same components as those of the device of FIG. 3 described above will be denoted by the same reference numerals. In the gasification furnace 6, the dispersion plate 3 is arranged below the fluidized bed forming region 20 in which the fluidized bed 2 is formed, and the waste supply port 1 is provided on the furnace wall above the region where the fluidized bed 2 is formed. Is provided. Further, at the position below the dispersion plate 3, the heating means 4 for initially heating the fluidized bed is provided on the furnace wall.
Is further connected, and one end of the cold air / heated air transfer path 12 communicates with the lower end of the gasification furnace 6.

On the other hand, a gas moving path 13 communicates with the upper part of the gasification furnace 6, and the gas moving path 13 extends to another place. An ammonia decomposing / removing device 15 is provided in the middle of the gas transfer path 13, and a heat exchanger 16 equipped with an oxidizing catalyst 9 is disposed downstream of the ammonia decomposing / removing device 15 to remove the heat The exchanger 16 has a gas flow path through which the gas moving along the gas moving path 13 moves, and an air flow path through which the air taken in from the outside by the air transporter 5 moves (both not shown), It is configured to exchange heat between the flow paths. In addition, an oxidizing catalyst 9 having an oxidizing performance is carried on the inner wall of the gas channel, and efficiently contacts the gas moving in the channel. The air flow path through which the air flows extends to the outside of the heat exchanger 16 and communicates with the cold air / heated air transfer path 12 described above.

The operation of the above apparatus will be described below. In the gasification furnace 6, an appropriate fluidized medium 7 is housed in the fluidized bed forming region, and the fluidized bed is formed by the air transporter 5 through the heat exchanger 16, the cold air / heated air transfer passage 11 and the dispersion plate 3. Air is delivered to the area 20 and the heating means 4
Is operated to heat the area 20. As a result, the fluidized medium 7 flows and the fluidized bed 2 having a considerably high temperature is formed. By inputting the organic waste into the fluidized bed 2 from the waste supply port 1, the organic waste is thermally decomposed in the fluidized bed 2 and the thermally decomposed gas 8 is generated. The pyrolyzed gas 8 is supplied to the gas transfer path 13 by the above-described air supply.
And is moved to the downstream area on the moving path 13.

The pyrolyzed gas 8 reaches the ammonia decomposing / removing device 15 by moving in the gas moving path 13, and the ammonia is decomposed and removed in the device 15. After that, the pyrolysis gas reaches the heat exchanger 16 and moves in the gas flow path in the heat exchanger 16. In the gas flow path, the oxidizing catalyst 9 carried on the inner wall comes into contact with the pyrolysis gas, and the oxidation performance of the catalyst causes low-temperature combustion of the pyrolysis gas to generate high-temperature combustion gas. The combustion gas moves through the gas flow passage in the heat exchanger 16 and transfers heat to the air flow passage through the flow passage wall. In the air passage, this heat heats the air moving in the passage, and the heated air passes from the cold air / heating air transfer passage 12 to the fluidized bed 2 through the dispersion plate 3 of the gasification furnace 6. be introduced. In the fluidized bed 2, the introduction of the heated air keeps the temperature at a high temperature even after the operation of the heating means 4 is stopped, and the continuously input waste is continuously pyrolyzed. Gas is generated. This allows the waste to be continuously processed.

In the heat exchanger 16, the combustion gas is transferred to an exhaust unit or the like (not shown). Ammonia is decomposed in the combustion gas by the ammonia decomposing / removing device 15 before the pyrolysis gas comes into contact with the oxidizing catalyst 9, so that NO _X can be prevented from being generated in the oxidizing catalyst 9.

FIG. 2 is a diagram showing the decomposition performance of ammonia by the ammonia decomposition catalyst used in the above-mentioned ammonia decomposition and removal device 15. Although ammonia was decomposed by the catalyst, the generation of NO _X was extremely small, and even if this treated gas was treated with an oxidizing catalyst, NO _x was generated.
It can be seen that the amount of _X generated is small.

[0025]

As described above, according to the present invention, the ammonia contained in the pyrolysis gas is removed, and then the pyrolysis gas is oxidatively decomposed by the oxidation catalyst. There is an effect that catalytic combustion treatment of organic waste without generation of oxide can be performed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a combustion device for organic waste according to an embodiment of the present invention.

FIG. 2 is also a graph showing the performance of the ammonia oxidation decomposition catalyst.

FIG. 3 is a conceptual diagram showing a conventional waste catalytic combustion device.

FIG. 4 is a graph showing ammonia decomposing performance of a platinum-based oxidation catalyst.

[Explanation of symbols]

1 Waste Supply Port 2 Fluidized Bed 3 Dispersion Plate 4 Heating Means 5 Pneumatic Transport Machine 6 Gasification Furnace 7 Fluidizing Medium 8 Pyrolysis Gas 9 Oxidizing Catalyst 10 Air Sent from Air Transport Machine 11 Heated by Oxidizing Catalyst and Flowing Air sent to the bed 13 Gas transfer path 15 Ammonia decomposition removal device 16 Heat exchanger 20 Fluidized bed formation region

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F23J 15/00 F27D 17/00 101A 4D004 F23L 15/00 104G 4D048 F27D 17/00 101 F23J 15/00 A 4K056 104 B01D 53/36 E G F term (reference) 3K023 QA11 QB10 QC08 3K061 AA11 AB02 AC01 BA04 CA00 EA01 EB15 3K065 AA11 AB02 AC01 BA04 JA05 JA15 3K070 DA02 DA14 DA01 DA04 CA01 CA04 CA01 CA04 4 AB03 BA30X CC32 CC34 CC38 CC44 CD10 4K056 AA19 CA11 CA20 DA02 DA26 DA32 DB09

Claims (6)

[Claims] 1. A method for combusting an organic waste, which comprises decomposing and removing an ammonia component in a pyrolysis gas generated by the organic waste, and then oxidizing and decomposing with an oxidation catalyst. 2. An organic waste is thermally decomposed in a fluidized bed to generate a thermally decomposed gas, and an ammonia component in the thermally decomposed gas is decomposed and removed in a downstream region where the thermally decomposed gas moves. The method for burning organic waste according to claim 1, wherein the pyrolysis gas is burned at a low temperature in a basin with a catalyst having an oxidizing performance. 3. The method according to claim 2, wherein the air is heated by the heat generated by the combustion of the catalyst having an oxidizing ability, and the heated air is introduced into the fluidized bed to maintain the fluidized bed at a high temperature. Method for burning organic waste in Japan. 4. An apparatus for combusting organic waste, characterized by decomposing and removing an ammonia component in a pyrolysis gas and then oxidizing and decomposing with an oxidation catalyst. 5. A fluidized bed forming region in which a fluidized bed for thermally decomposing waste is formed, and a gas moving path through which a thermally decomposed gas generated by the thermal decomposition moves, 5. The apparatus for combusting organic waste according to claim 4, wherein a means for decomposing ammonia in the cracked gas and an oxidizing catalyst having an oxidizing performance are arranged along the flow direction. 6. An air heating unit for heating air by heat generated by low temperature combustion of pyrolysis gas in the catalyst filter is provided, and the air heated by the air heating unit is supplied to the fluidized bed forming region. The apparatus for burning organic waste according to claim 4 or 5, further comprising a heated air transfer path for transferring the heated air.