JP2004239687A - Pyrolizing furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire pyrolysis gas having a small dust content, to control properly a pyrolytic reaction, and to miniaturize the whole device, concerning a pyrolizing furnace. <P>SOLUTION: This furnace comprises a tube furnace 2 having an inlet 21 of a processing object a such as an organic waste on one end and outlets 22b, 22c of the pyrolysis gas b and a pyrolysis residue c on the other end. The tube furnace 2 is provided with a tubular porous partition 6 constituting a furnace wall as a boundary for partitioning a pyrolytic reaction area 3 for pyrolizing the processing object a at the temperature of 300-600°C in a poor oxygen atmosphere from a pyrolysis gas discharge passage 4. On the outer circumferential side of the tube furnace 2, an induction coil 51 as an induction heating means for heating the processing object up to a pyrolysis temperature is provided. A moving means comprising a rotary screw 7 is disposed inside the porous partition 6. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a treatment system for thermally decomposing organic waste.
[0002]
[Prior art]
Conventionally, as a system for thermally decomposing organic substances in waste, a waste heat treatment apparatus as illustrated in FIG. 3 is known. (See Patent Document 1)
[0003]
[Patent Document 1]
JP-A-64-49816: Claims, description of FIG. 1 and description of examples (page 5, lower right column to page 6, lower left column).
[0004]
In this apparatus, a waste a containing organic matter is thermally decomposed in a pyrolysis drum reactor 11 operated at 300 to 600 ° C. under an oxygen cutoff, and a generated pyrolysis gas b is taken out from an upper part of an unloading device 12. It is sent to the high temperature combustion chamber 13 and is set to completely burn at 1200 ° C. or more in the presence of oxygen. The non-volatile residue in the pyrolysis drum reactor 11 is taken out from the lower part of the carry-out device 12, and is separated and recovered into a combustible component and an incombustible component.
[0005]
The high-temperature exhaust gas generated in the high-temperature combustion chamber 13 is released to the atmosphere via a steam generator 14, a dust remover 16, an exhaust gas purifier 17, and a chimney 18. Then, the high-pressure steam obtained by the steam generator 14 is supplied as a power source of the turbine generator 15. Thus, the potential thermal energy in the waste a containing organic matter is converted into electric energy.
[0006]
In an actual pyrolysis drum reactor, the object to be processed undergoes pyrolysis while rolling in the rotating drum, so it is difficult to reduce the size of the apparatus, and the thermal decomposition reaction that occurs in stages is difficult. Correspondingly, it was difficult to control the atmosphere such as temperature. In addition, since the generated pyrolysis gas contains a large amount of dust, there is also a problem to be solved in that the load on an exhaust gas dust removing device or the like increases.
[0007]
When treating radioactive waste, such a pyrolysis method can be expected to greatly reduce the volume, but on the other hand, in response to the demand that it is desirable to keep the radionuclide in the smallest possible area, In this pyrolysis drum reactor, it was difficult to cope with the problem because the pyrolysis gas was taken out along with the nuclides.
In particular, when processing radioactive waste such as resin waste, which has a high radioactivity concentration that is inaccessible to humans, the large size of the equipment requires a great deal of cost for remote maintenance equipment, and it is also necessary to recover from trouble. It is likely to be accompanied by significant difficulties.
[0008]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and a pyrolysis gas having a low dust content can be obtained, a pyrolysis reaction can be appropriately controlled, and the entire apparatus can be downsized. Provide a pyrolysis furnace. In particular, the present invention provides a compact pyrolysis furnace capable of pyrolyzing radioactive waste such as resin waste having a high radioactivity concentration while suppressing the diffusion of nuclides.
[0009]
[Means for Solving the Problems]
The above problem is that, in a pyrolysis furnace that pyrolyzes an object to be processed to generate a pyrolysis gas and a pyrolysis residue, part or all of the wall surface of the pyrolysis furnace body is formed of porous partition walls. The problem can be solved by the pyrolysis furnace of the present invention, wherein the pyrolysis gas is taken out through the porous partition. In this case, preferably, a pyrolysis gas discharge flow path is provided outside the pyrolysis gas discharge flow path.
[0010]
In the present invention, it is preferable that the porous partition wall is formed of one or a combination of two or more of a ceramic porous body, a sintered metal porous body, a metal fiber fabric, a metal net and a metal net laminate. It is preferable that a means for moving an object to be processed is provided in the pyrolysis furnace main body. Further, it is preferable that the atmosphere such as the temperature, the oxygen concentration, the nitrogen concentration, and the water vapor concentration in the pyrolysis furnace main body be variable along the moving path of the moving means.
[0011]
Further, the present invention is preferably embodied in that the moving means is a rotary screw. It is preferable to supply a fluid for adjusting the atmosphere such as temperature, oxygen concentration, nitrogen concentration, and water vapor concentration in the pyrolysis furnace main body into the pyrolysis furnace main body through a supply path provided in a shaft of the rotary screw. As the atmosphere adjusting fluid for this purpose, one or a combination of two or more of nitrogen gas, oxygen gas, air, steam, and water, and a fluid in which the temperature adjusting fluid heats the fluid may be applied. .
[0012]
Further, in the present invention, it is preferable to heat the furnace body or the furnace body and the pyrolysis gas discharge channel by induction heating means provided outside the furnace body of the pyrolysis furnace. It is particularly preferable to arrange a heating medium heated by the induction heating means, and to heat the furnace body or the pyrolysis gas discharge channel by radiation and heat conduction from the heating medium.
In addition. It is also preferable that the moving direction of the moving means is set downward at an angle of up to 30 ° with respect to the horizontal direction.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the pyrolysis furnace of the present invention will be described with reference to FIG. 1 and FIG. 2 which is a partially enlarged view of FIG.
The pyrolysis furnace of this embodiment has one end serving as an inlet 21 for an object a to be treated such as organic waste and the other end serving as outlets 22b and 22c for a pyrolysis gas b and a pyrolysis residue c. Is formed in a tubular furnace 2, and inside the tubular furnace 2, a pyrolysis reaction zone 3 and a pyrolysis gas discharge channel 4 for thermally decomposing the treatment target a in an oxygen-deficient atmosphere at a temperature of 300 to 600 ° C. A tubular porous partition 6 constituting the wall surface of the pyrolysis furnace main body is provided as a boundary for partitioning.
[0014]
On the outer peripheral side of the tubular furnace 2, an induction coil 51 is provided as induction heating means for heating the object to be processed to the pyrolysis temperature. In FIG. 1, a heating medium 52 heated by the induction coil 51 is annularly arranged between the tubular furnace 2 and the induction coil 51, and the furnace body is heated by radiation and heat conduction from the heating medium 52. Like that.
[0015]
A preferable material of the heating medium 52 is an electric induction material such as stainless steel or carbon steel. However, when an electric induction material is used as the outer peripheral component of the tubular furnace main body 2, the arrangement of the heating medium 52 is omitted. It is possible. In addition, the reason why the heating medium is purposely installed in FIG. 1 is as follows. That is, since the pyrolysis furnace body may need to be replaced due to corrosion by the pyrolysis gas, by reducing the replacement range as much as possible, the load of the replacement work can be reduced and the generated secondary waste can be reduced. That's why.
[0016]
Next, the internal structure of the tubular furnace 2 will be described in detail.
The porous partition wall 6 is used in direct contact with the pyrolysis residue to separate and extract the pyrolysis gas generated in the pyrolysis reaction zone 3 from the pyrolysis residue. A durable heat-resistant material is used. Preferred materials include a porous ceramic body, a sintered metal porous body, a metal fiber woven fabric, a metal net and a metal net laminate, and these are preferably used alone or in combination of two or more.
[0017]
The shape of the porous partition wall 6 may be a slit, a spot, or a spiral in combination with a heat-resistant metal plate, in addition to a tubular shape. When a large amount of pyrolysis gas is generated, a tubular shape is preferable, and when a pyrolysis furnace requires strength, a slit shape or a spot shape is preferable. The spiral shape is difficult to construct, but has the advantage of being able to cope with large amounts of pyrolysis gas and of increasing the strength of the pyrolysis furnace.
[0018]
It is desirable that the installation direction of the porous partition wall 6 be long along the moving means 7 of the object to be processed installed in the tubular furnace. This is because when the temperature and atmosphere in the tubular furnace are set stepwise, various types of decomposed gas generated according to each condition can be quickly discharged in the vicinity of the generated part, thereby bringing the system into a non-equilibrium state. This is because the decomposition can be promoted by keeping the temperature at.
[0019]
Further, by doing so, it is also useful to prevent the decomposition gas from flowing to a region other than the generation portion and adversely affecting the pyrolysis reaction originally expected in the region. Therefore, it is desirable that the total length of the porous partition wall in the direction along the moving means 7 for the object to be treated is as large as possible with respect to the entire length of the pyrolysis furnace main body, preferably 50% or more, and ideally 70% or more. % Or more is good.
[0020]
In the present invention, there is an important point in that the wall surface of the pyrolysis furnace main body is formed as the porous partition wall 6, and the gas generated by the pyrolysis is discharged outside the furnace through the porous partition wall 6. Is compact and the dust in the pyrolysis gas is filtered by the porous partition walls 6, so that the load on the subsequent exhaust gas treatment system is reduced. For example, the dust removal device provided at the subsequent stage can be downsized, and maintenance can be performed. Special advantages are obtained, such as the load can be reduced.
[0021]
Furthermore, when the pyrolysis furnace of the present invention is applied to treat waste resin, which is radioactive waste, radioactive solid substances are suppressed from being discharged along with pyrolysis gas, and the pyrolysis residue is small in volume. This is particularly advantageous for the treatment of radioactive waste, since most will remain in it. Further, in the present invention, since induction heating is employed, maintenance and management are easier than in a normal carbonization furnace, and as a pyrolysis furnace for radioactive waste, the access of workers can be suppressed as much as possible. It is.
[0022]
To explain a preferred embodiment of the present invention, a moving means including a rotary screw 7 is provided in the pyrolysis reaction zone 3 formed inside the porous partition wall 6. Then, the rotary screw 7 thermally decomposes the processing object a sent from the inlet 21 while sequentially moving the object a through the pyrolysis reaction zone 3 toward the outlet. Extracted into the pyrolysis gas discharge channel 4 through the porous partition 6 and taken out from the pyrolysis gas outlet 22b. On the other hand, the pyrolysis residue is moved to the pyrolysis residue outlet 22c by the rotary screw 7 and discharged.
[0023]
In the present invention, a rotating screw is adopted as a preferable moving means, but the present invention is not limited to this, and a moving means such as a push-in pusher method or a bucket conveyor method may be used.
In the present invention, by combining the moving devices in this manner, the uniformity of the thermal decomposition reaction can be improved, and further, there is an advantage that the moving device provided outside the furnace is not required and the space and the like can be saved. .
[0024]
Further, in the figure, the pyrolysis furnace is installed substantially horizontally, but the installation angle of the pyrolysis furnace is set so that the moving direction of the moving means is downward at an angle of up to 30 ° with respect to the horizontal direction. Can be done. By facing downward as described above, the dischargeability of the decomposition residue is improved, and the possibility of sticking to the screw is reduced, so that there is an advantage that trouble is reduced and maintenance is facilitated.
[0025]
Next, in the pyrolysis reaction zone 3 of the present invention, the reaction conditions such as temperature, oxygen concentration, nitrogen concentration, water vapor concentration, etc. are set on the moving route by the moving means so that the most preferable pyrolysis reaction proceeds. It is configured so that it can be set to be appropriately variable along the line.
[0026]
Specifically, a fluid for adjusting the atmosphere such as the temperature, the oxygen concentration, the nitrogen concentration, and the water vapor concentration in the pyrolysis reaction zone 3 is supplied to the pyrolysis reaction zone 3 so that the fluid is provided in the shaft of the rotary screw 7. A fluid supply path 71 is provided, and a plurality of discharge ports 72 are provided in the supply path 71 at appropriate intervals. A required fluid is fed from one of the supply ports 73 and dispersed in the thermal decomposition reaction zone 3. It can be supplied.
[0027]
Thus, the atmosphere obtained by adjusting the number and locations of the outlets 72 can be preferably changed along the movement path.
The atmosphere adjusting fluid used for this purpose is one of nitrogen gas, oxygen gas, air, water vapor, water, or a combination of two or more as necessary. The fluid may be heated to an appropriate temperature before use.
[0028]
As described above, in the present invention, the tubular pyrolysis furnace and the screw-type moving device are combined, so that the installation space for the decomposition furnace can be further reduced. In addition, since a supply path for atmosphere adjusting fluid such as nitrogen gas and oxygen gas is provided in the screw shaft, the atmosphere inside the furnace can be controlled and the pyrolysis gas can be quickly taken out of the furnace. Another advantage is that no device is required.
[0029]
Further, in the present invention, the object to be treated is guided into an appropriate atmosphere such as temperature while gradually progressing in the thermal decomposition reaction zone, so that it is possible to control the preferable decomposition reaction to occur. For this reason, troubles such as explosive generation of decomposition gas can be resolved, and multiple pyrolysis operation modes changed according to the content of processing can be performed in this single decomposition furnace. There are many benefits.
[0030]
【The invention's effect】
Since the pyrolysis furnace of the present invention is configured as described above, a pyrolysis gas having a low dust content can be obtained, the pyrolysis reaction can be appropriately controlled, and the size of the entire apparatus can be reduced. In particular, as an apparatus for treating radioactive waste such as resin waste having a high radioactivity concentration, thermal decomposition can be performed while suppressing the diffusion of nuclides. Therefore, there is an excellent effect that a pyrolysis furnace that is safe and easy to maintain can be provided. Therefore, the present invention has extremely high technical value as a pyrolysis furnace which has solved the conventional problems.
[Brief description of the drawings]
FIG. 1 is a sectional configuration view of a main part for describing an embodiment of the present invention.
FIG. 2 is a partially enlarged view of FIG.
FIG. 3 is a main block diagram showing a flow of a conventional thermal decomposition system.
[Explanation of symbols]
2 Furnace body, 21 inlet, 22b, 22c outlet, 3 pyrolysis reaction zone, 4 pyrolysis gas discharge channel, 51 induction coil, 52 heating medium, 6 porous partition, a workpiece, b pyrolysis gas, c Pyrolysis residue.

Claims (11)

A pyrolysis furnace for pyrolyzing an object to be processed to generate a pyrolysis gas and a pyrolysis residue, wherein a part or all of a wall of a pyrolysis furnace body is constituted by a porous partition wall. Furnace. The pyrolysis furnace according to claim 1, wherein a pyrolysis gas discharge channel is provided outside the porous partition, and the pyrolysis gas is taken out through the porous partition. 3. The porous partition according to claim 1, wherein the porous partition wall is formed of one or a combination of a ceramic porous body, a sintered metal porous body, a metal fiber fabric, a metal net, and a metal net laminate. Pyrolysis furnace. The thermal decomposition furnace according to any one of claims 1 to 3, wherein a moving means of the object to be processed is provided in the thermal decomposition furnace main body. The pyrolysis furnace according to claim 4, wherein an atmosphere such as a temperature, an oxygen concentration, a nitrogen concentration, and a water vapor concentration in the pyrolysis furnace main body is variable along a moving path by the moving means. The pyrolysis furnace according to claim 4 or 5, wherein the moving means is a rotary screw. The heat according to claim 6, wherein a fluid for adjusting an atmosphere such as a temperature, an oxygen concentration, a nitrogen concentration, and a water vapor concentration in the pyrolysis furnace main body is supplied through a supply path provided in a shaft of the rotary screw. Decomposition furnace. 8. The atmosphere adjusting fluid according to claim 7, wherein the atmosphere adjusting fluid is one or a combination of two or more of nitrogen gas, oxygen gas, air, water vapor, and water, and the temperature adjusting fluid is obtained by heating the fluid. Pyrolysis furnace. The pyrolysis furnace according to any one of claims 1 to 8, wherein the furnace main body or the furnace main body and the pyrolysis gas discharge channel are heated by induction heating means provided outside the pyrolysis furnace main body. A heating medium to be heated by the induction heating means is arranged between the induction heating means and the furnace body or the pyrolysis gas discharge flow path, and the furnace body or the furnace body is heated by radiation and heat conduction from the heating medium. The thermal cracking furnace according to claim 9, wherein the cracked gas discharge channel is heated. The pyrolysis furnace according to any one of claims 4 to 10, wherein a moving direction of the moving means is set downward at an angle of up to 30 ° with respect to a horizontal direction.

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