JP2007051209A - Pyrolysis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pyrolysis apparatus which can reduce the amount of char particles accompanied with pyrolyzed gases. <P>SOLUTION: The pyrolysis apparatus is equipped with a rotary kiln 10 for generating pyrolyzed gases 2 and pyrolysis residue 3 by pyrolyzing waste 1, discharges the pyrolyzed residue generated in the rotary kiln to an outlet hopper 20, is equipped with a separation device 30 for recovering pyrolyzed residue particles accompanied with the pyrolyzed gases. The separation device is equipped with a cylindrical main body 31 for passing the pyrolyzed gases, an inlet pipe 35 for flowing the pyrolyzed gases generated in the kiln into the cylindrical main body and a return pipe 37 opening in the cylindrical main body in the downstream of the inlet pipe and discharging recovered pyrolyzed residue particles 4 to the outlet hopper 20. The cross section of the outlet hopper connected to the kiln is brought to have ≤0.1 m/sec maximum flow rate of the pyrolyzed gases at the outlet opening of a retort 11 of the rotary kiln. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the heat of waste in a gasification and melting apparatus in which waste such as municipal waste is pyrolyzed using a rotary kiln to separate the pyrolysis residue (char) and pyrolysis gas. The present invention relates to a decomposition apparatus.

  As a technology for treating waste such as municipal waste, the waste is put into a pyrolysis furnace and pyrolyzed (dry distillation and gasification), and the generated combustible pyrolysis gas and char are separated from the pyrolysis furnace. There is a technique for taking them out and sending them to the next process for processing. A rotary kiln is generally used for the pyrolysis furnace, and many types are heated by external heat.

  Pyrolysis gas and char generated using a rotary kiln can be used as fuel, so it is often used as a heat source necessary for waste disposal, and pyrolysis gas is also generally used as a heat source for external heat of the rotary kiln. Has been done.

  When pyrolysis gas is used as a heat source for a rotary kiln, the pyrolysis gas taken out of the rotary kiln is burned in a furnace or burner (hereinafter referred to as a combustion burner) with an ignition device and converted into high-temperature exhaust gas, which is mixed with waste. Divide them into the rotary kiln so that there is no such thing.

  In the rotary kiln, waste is sent into a rotating cylinder (retort) so that this exhaust gas and waste do not mix, and in the gap between the container (jacket) partitioned by a heat insulating material and outside the retort so that it does not mix with outside air. The exhaust gas is flowed and heat is exchanged from the exhaust gas to the waste through the retort, and the waste is thermally decomposed in a low oxygen atmosphere.

  Since the exhaust gas exhausted from the jacket after heat exchange is sufficiently high in temperature, it is sent to a boiler that changes water into steam or a heat exchanger that warms the air, and then exchanges heat. Gases and particles are reduced by a filter and released to the atmosphere. The technology of such a rotary kiln type thermal decomposition apparatus is described in Patent Document 1, for example.

JP 2003-183665 A

  The pyrolysis gas generated in the rotary kiln of the rotary kiln type pyrolysis device is mixed with the micro-sized, low-mass pyrolysis residue particles (char particles) formed in the stage of the gas itself. Even if it is burned with pyrolysis gas by the combustion burner and changed to fly ash (hibashi), it will flow further downstream with the exhaust gas, the retort outer surface of the rotary kiln, the inside of the jacket, the boiler placed downstream of it, the heat Reach up to the exchanger and filter.

  Such fly ash adheres to the surface of the rotary kiln's retort, boiler, and heat exchanger tubes to reduce the heat exchange efficiency of each device, and the burner, jacket, boiler, heat exchanger tube gaps and This may cause an adverse effect of gradually clogging the exhaust gas flow path such as the gap of the filter.

  In order to eliminate this adverse effect, the thermal decomposition equipment can be used to clean or replace the adhering fly ash by periodically opening the jacket, combustion burner, boiler, heat exchanger and piping connecting them, and the flow path. The maintenance cost will be worsened.

  Further, when char particles are mixed with the pyrolysis gas, the amount of char that is generated in the rotary kiln and recovered by the outlet hopper is reduced, resulting in loss of char as fuel. Furthermore, when char particles that also serve as fuel are mixed with the pyrolysis gas, not only the combustion state in the combustion burner becomes unstable, but also the heat exchange performance in the rotary kiln and boiler tends to become unstable.

  In order to remove char particles that may cause such a problem, a separator (a cyclone separator or a screw) that removes the char particles from the pyrolysis gas may be provided upstream of the combustion burner.

  Since these separators are gradually filled with the separated char particles, it is necessary to periodically discharge the char particles separated from the inside of the separator. In order to collect the separated char particles in a separate container and carry them out, it is necessary to store them in a low oxygen state until the temperature drops so as not to ignite. Further, in order to return the separated char particles to the rotary kiln or the outlet hopper, the char particles are again entrained in the pyrolysis gas by being mixed again with the flow of the pyrolysis gas inside the outlet hopper. In addition, entrainment means that char particles ride along the flow of pyrolysis gas.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a pyrolysis apparatus capable of reducing the amount of char particles entrained in the pyrolysis gas generated in the rotary kiln. It is to provide. It is another object of the present invention to provide a thermal decomposition apparatus capable of forming a thermal decomposition gas flow inside the outlet hopper so that char particles are not easily accompanied.

  In order to achieve the above object, a pyrolysis apparatus according to the present invention includes a kiln that pyrolyzes waste to generate pyrolysis gas and pyrolysis residue, and the pyrolysis residue generated in the kiln is supplied to an outlet hopper. A separation device that collects the pyrolysis residue particles that are discharged and entrained in the pyrolysis gas, that is, that flows out together with the pyrolysis gas, includes a cylindrical body that allows the pyrolysis gas to pass through, An inlet pipe connected to the upstream side of the cylindrical body and into which the pyrolysis gas generated in the kiln flows, and the recovered pyrolysis residue particles opened to the cylindrical body downstream of the inlet pipe and discharged to the outlet hopper And a return pipe.

  The thermal decomposition apparatus of the present invention configured as described above collects pyrolysis residue particles that accompany the pyrolysis gas generated in the rotary kiln and flows out along with the gas, and the recovered pyrolysis residue particles are pyrolyzed. Since the gas is collected through an inlet pipe and a separate return pipe, it is prevented from being entrained in the pyrolysis gas again, and is discharged together with the pyrolysis residue collected as a solid component. The decomposition residue can be increased. In addition, accumulation of pyrolysis residue particles flowing along with pyrolysis gas in the flow passage can be prevented, the amount of fly ash due to combustion of pyrolysis gas can be reduced, and maintenance of the apparatus can be simplified. The cycle can be lengthened.

  Another aspect of the pyrolysis apparatus according to the present invention includes a kiln that pyrolyzes waste to generate pyrolysis gas and pyrolysis residue, and discharges the pyrolysis residue generated in the kiln to an outlet hopper. A separation device for collecting pyrolysis residue particles accompanying the pyrolysis gas, that is, flowing out together with the pyrolysis gas. The separation device includes a cylindrical main body through which the pyrolysis gas passes, and the cylindrical shape. And a return pipe having a lower opening for discharging the recovered pyrolysis residue particles connected to the main body to the outlet hopper, and on the upper part of the return pipe, the pyrolysis generated in the kiln An opening for allowing gas to flow into the cylindrical main body is formed.

  In the pyrolysis apparatus configured as described above, the generated pyrolysis gas flows into the cylindrical main body from the opening formed in the upper part of the return pipe of the separation apparatus, and heat is generated while passing through the cylindrical main body. Decomposition residue particles are separated and deposited in the cylindrical body. When the separator is activated, the deposited pyrolysis residue particles are discharged to the outlet hopper through the opening below the return pipe and collected. The recovered pyrolysis residue particles are unlikely to flow into the cylindrical body again due to the pyrolysis gas flowing from the upper opening and flowing through the return pipe, and the pyrolysis residue entrained by the pyrolysis gas. Can be reduced.

  Moreover, as a preferable specific aspect of the thermal decomposition apparatus according to the present invention, the separation apparatus includes a spiral blade wound spirally inside the cylindrical body, and the thermal decomposition is performed inside the cylindrical body. Gas is allowed to pass through and the pyrolysis residue particles are separated and deposited by the swirl flow formed by the swirl vanes, and the deposited pyrolysis residue particles are collected by scraping off the swirl vanes. Yes.

  The pyrolysis apparatus configured in this manner generates a swirling flow inside the cylindrical body to separate and deposit the pyrolysis residue particles, and the pyrolysis residue particles flowing together with the pyrolysis gas are deposited on the inner wall of the cylindrical body. When depositing, the swirl vanes are swirled to peel off the deposits, and the piled particle deposits are sent upstream by swirl vanes and recovered from the outlet hopper through the return pipe, increasing the amount of recovered pyrolysis residue. It is possible to reduce the maintenance work of the separation apparatus by stripping off the pyrolysis residue adhering to the pyrolysis gas flow passage such as piping.

  The lower end opening of the return pipe is preferably extended to a position below the upper end of the outlet opening of the kiln. If comprised in this way, since the pyrolysis residue particle | grains produced | generated in the kiln are difficult to enter from the lower end opening part of the return pipe of a separator, the quantity of the pyrolysis residue particle which flows out accompanying a pyrolysis gas is reduced. be able to.

  As another aspect of the thermal decomposition apparatus according to the present invention, the thermal decomposition apparatus includes a plurality of the separation apparatuses, and each of the plurality of separation apparatuses includes an on-off valve for stopping the inflow of the thermal decomposition gas, During the recovery, the flow of the pyrolysis gas to the separation device is stopped. When the pyrolysis apparatus configured in this manner has a large amount of pyrolysis residue particles accumulated in the cylindrical main body, the pyrolysis gas is stopped from flowing into the separation apparatus and is accumulated by rotating the swirl vane. Since the pyrolysis gas generated by stripping off the particles can recover pyrolysis residue particles by another separation device, re-entrainment of the pyrolysis residue particles into the pyrolysis gas can be prevented.

  It is preferable to set the flow path cross section of the outlet hopper continuous to the kiln so that the maximum flow rate of the pyrolysis gas at the outlet opening of the kiln is 0.1 m or less per second. That is, the horizontal sectional area of the kiln outlet hopper is set so that the maximum flow velocity is 0.1 m or less per second in accordance with the amount of pyrolysis gas generated at the time of rating of the pyrolysis apparatus. The pyrolysis apparatus configured in this manner reduces the amount of pyrolysis residue particles accompanying the pyrolysis gas because the maximum flow velocity of the pyrolysis gas flowing out of the kiln is gently set to 0.1 m or less per second. be able to. That is, in this pyrolysis apparatus, the outlet hopper is set so that char particles are not easily entrained in the pyrolysis gas by setting the cross section of the outlet hopper so that the maximum flow rate of the pyrolysis gas is 0.1 m or less per second. An internal pyrolysis gas stream can be formed.

  The present invention relates to a pyrolysis apparatus comprising a kiln that pyrolyzes waste to generate pyrolysis gas and pyrolysis residue, and the char generated by the kiln and accompanied by the pyrolysis gas flowing from the outlet hopper to the separation apparatus. The amount of particles can be reduced. Further, it is possible to form a pyrolysis gas flow inside the outlet hopper so that char particles are not easily entrained in the generated pyrolysis gas. Therefore, it is possible to obtain a thermal decomposition apparatus that is stable and has high performance and has a low maintenance cost.

  Hereinafter, a first embodiment of a thermal decomposition apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the main configuration of the thermal decomposition apparatus according to the present embodiment, FIG. 2 is an enlarged cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is a ribbon screw arranged in the separation apparatus. FIG. Figure 1 shows the cross section of the rotary kiln and outlet hopper, the cross section of the separator, the combustion burner and heat exchanger, and the flow of pyrolysis gas and pyrolysis residue (char) generated in the rotary kiln. Show.

  1-3, the thermal decomposition apparatus of this embodiment is continuous with the rotary kiln 10 which thermally decomposes the waste 1 and produces | generates the pyrolysis gas 2 and the thermal decomposition residue 3, and the right side opening of a rotary kiln in FIG. And an outlet hopper 20 for discharging the generated pyrolysis gas and pyrolysis residue. The rotary kiln 10 is provided with a pipe-shaped retort 11, and the retort 11 is installed in a substantially horizontal state, and the left end in FIG. 1 is an opening through which waste 1 is carried from an inlet hopper (not shown) by a rotary conveyor or the like. It has become. A jacket 12 is positioned on the outer periphery of the retort 11, and the retort 11 can rotate in the jacket 12. The rotary kiln 10 is preferably installed in a horizontal state or so as to descend slightly from the horizontal state in the exit direction.

  The rotary kiln 10 is configured such that a pipe-shaped retort 11 is supported at both ends by a rotation support 13 such as a roller or a tire, and is gently rotated by a rotation drive device (not shown) via a belt, a chain, or the like. Yes. A high-temperature exhaust gas from a combustion burner, which will be described later, is supplied to a space 14 between the jacket 12 located on the outer periphery of the retort 11 so that the waste 1 supplied into the retort 11 is heated and thermally decomposed. It is configured. The space between the retort 11 and the jacket 12 is sealed in an airtight state so that combustion gas does not leak outside.

  A separation device 30 is disposed adjacent to the rotary kiln 10 for separating and recovering the pyrolysis residue in the pyrolysis gas. In the separator 30, the pyrolysis residue particles (char particles) 4 are separated while the pyrolysis gas 2 a passes, and the pyrolysis gas 5 from which the char particles have been separated is supplied to the combustion burner 50. In this combustion burner 50, the pyrolysis gas 5 from which the pyrolysis residue particles 4 have been separated is burned, and high-temperature combustion gas 6 is supplied to the space between the retort 11 and the jacket 12 of the rotary kiln 10 to remove the waste in the rotary kiln. It is configured to heat. The combustion gas 7 that has heated the rotary kiln 10 passes through the heat exchanger 60, and the fly ash is removed by a filter device (not shown) so as to be discharged into the atmosphere as exhaust gas 8.

  The separator 30 closes both ends of a cylindrical main body 31 formed of a pipe, and in FIG. 1, the right end side is the upstream side and the left end side is the downstream side. Inside the cylindrical main body 31, a ribbon screw 32 is arranged as a swirl vane and is configured to be rotated in a certain direction by a driving device 33 such as a motor fixed on the upstream side of the cylindrical main body 31. The ribbon screw 32 is loosely fitted in the cylindrical main body 31, and the outer diameter of the ribbon screw 32 is set smaller than the inner diameter of the cylindrical main body 31, so that the inside of the cylindrical main body can be rotated while contacting the inner wall surface. It is configured.

  The ribbon screw 32 is formed by spirally winding a metal plate material having a predetermined width, and an inner flow path 34 through which pyrolysis gas can pass is shown in FIG. 3 at the center of the wound metal plate material. It is formed to be. The pyrolysis gas passing through the cylindrical main body 31 is swirled by the ribbon screw 32, and centrifugal force is applied to the pyrolysis residue particles accompanying the gas to separate the particles from the gas flow. it can. The ribbon screw 32 is rotated by the driving device 33 to peel off the char particles 4 deposited on the inner wall of the cylindrical main body 31 and to transport the peeled char particles to the upstream side.

  An inlet pipe 35 through which pyrolysis gas flows is connected to the upstream end of the cylindrical body 31 of the separation device 30, and the lower end of the inlet pipe communicates with the upper part of the outlet hopper 20. Further, an outlet pipe 36 that supplies the pyrolysis gas that has passed through the separation device 30 to the combustion burner 50 is connected to the downstream end of the cylindrical main body 31. Further, a return pipe 37 is connected to the upstream side of the cylindrical body 31 downstream from the inlet pipe 35. The return pipe 37 has a function of discharging the char particles 4 separated by the separation device 30 and transported by the ribbon screw 32 from the cylindrical main body 31 and returning them to the outlet hopper 20.

  The lower end opening of the return pipe 37 is extended to a position lower than the upper end of the outlet opening of the retort 11 of the rotary kiln 10. Actually, the lower end opening of the return pipe extends to a position below the lower end of the outlet opening of the retort. By setting the position of the lower end opening of the return pipe in this way, hot pyrolysis gas flows out to the outlet hopper 20 along the upper edge of the exit opening of the kiln. Therefore, the char particles falling in the return pipe can be prevented from flowing into the cylindrical main body 31 of the separation device again on the rising air stream of the pyrolysis gas.

  The operation of the thermal decomposition apparatus of the present embodiment configured as described above will be described below. Waste 1 such as municipal waste is first subjected to pretreatment such as pulverization and drying, and is then placed in a high temperature retort 11 in a rotary kiln 10 by a belt conveyor (not shown). The waste 1 is heated and thermally decomposed in a low oxygen state inside the retort 11 and separated into a pyrolysis residue 3 in which a combustible pyrolysis gas 2, a char and a high melting point incombustible material are mixed, and the pyrolysis residue 3 is retort 11. With this rotational stirring behavior, it is gradually sent downstream (rightward), falls below the outlet hopper 20, and is discharged out of the furnace.

  On the other hand, the pyrolysis gas 2 is mixed with char particles 4 having a small size and a low mass along with the flow of the gas itself. The particles flow to the separation device 30 through the inlet pipe 35 and are attached inside the separation device. The char particles 4 are centrifuged by flowing spirally through the inner flow path 34 at the center of the cylindrical main body 31 while being swirled by the ribbon screw (swirl blade) 32.

  The pyrolysis gas 5 from which the pyrolysis residue particles have been collected by centrifugation is burned by the combustion burner 50 through the piping from the outlet pipe 36, is changed to the high-temperature combustion gas 6, and is retort so as not to be mixed with the waste through the piping. The waste inside the retort 11 is heated and thermally decomposed while flowing through a space 14 between the jacket 12 partitioned by a heat insulating material and outside the retort so as not to be mixed with the outside air. In addition, in the state before pyrolysis gas is produced | generated, the fuel gas supplied separately is burned with the combustion burner 50, and the rotary kiln 10 is heated.

  Since the temperature of the combustion gas 7 coming out of the jacket 12 is sufficiently high, it is further sent to a boiler that changes water into steam or a heat exchanger 60 that heats the air to exchange heat. The particles are reduced by a filter and discharged as exhaust gas 8 into the atmosphere.

  The char particles 4 accompanying the pyrolysis gas are separated and deposited in the separation device 30. When the amount of the char particles 4 increases, the drive device 33 is operated to collect the char particles. When the driving device 33 is operated, the ribbon screw 32 positioned in the cylindrical main body 31 is rotated in the direction opposite to the spiral direction, and the outer periphery of the ribbon screw peels off the char particles adhering to the inner wall surface of the cylindrical main body 31. . The peeled off char particles are deposited on the bottom surface of the cylindrical main body 31, and are conveyed upstream by the ribbon screw 32, that is, in the right direction. The transported char particles are dropped into a return pipe 37 that opens to the downstream side of the inlet pipe 35, discharged into the outlet hopper 20, and collected from the outlet of the hopper. Since the char particles falling through the return pipe 37 fall without being affected by the pyrolysis gas flowing through the inlet pipe 35, the char particles are prevented from flowing out again with the pyrolysis gas.

  Here, the behavior of the char particles contained in the pyrolysis gas flowing in the kiln outlet hopper 20 according to the present invention will be described below.

  FIG. 4A shows a ratio N (%) in which the number of particles with respect to the diameter d of the char particles contained in the pyrolysis gas is normalized by the maximum ratio, and FIG. 4B shows a small ratio of FIG. The ratio Γ (%) accumulated from the direction is shown. FIG. 5 shows the critical flow velocity Um accompanying the pyrolysis gas with respect to the diameter d of the char particles. FIG. 6 shows the ratio N of the number of particles that are entrained by the pyrolysis gas and flow out with respect to the diameter d of the char particles. FIG. 4 shows a case where char particles obtained by sampling (sampling) a part of the pyrolysis gas generated in the kiln are examined. At this time, the gas flow is not taken into consideration. On the other hand, in FIG. 5 and FIG. 6, since the char particles entrained in the pyrolysis gas flow are examined, the gas flow is naturally taken into consideration.

  FIG. 4 will be described.

  In general, the fine particles entrained in the airflow often have a mountain-shaped distribution (distribution approximated by a logarithmic distribution) that is biased toward a relatively small diameter, and the char accompanying the pyrolysis gas flow as shown in FIG. The same applies to the particles. The cumulative ratio for this distribution increases rapidly near the top of the particle number ratio, increasing the particle number ratio on the smaller diameter side than the diameter at which this particle number ratio increases rapidly, or on the larger diameter side. The increase in the number ratio of particles is moderate.

  The cumulative ratio Γ of char particles contained in the pyrolysis gas increases rapidly with the particle diameter d having the maximum value of the ratio N of the number of particles. In the conventional example, Γ increases rapidly at d = 30 μm where N is maximized. At d = 30 μm, Γ = 40%. Here, the volume and mass of the char particles contained in the pyrolysis gas are proportional to the cube of the particle diameter. From this, the ratio of the volume or mass of char particles of 30 μm or more to the total volume or mass of char particles contained in the pyrolysis gas in the conventional example is Γ = 100 of 30 μm or more contained in the pyrolysis gas in the conventional example. Occupies a proportion larger than −40 = 60%. Therefore, it can be said that the technical problem in the conventional example corresponds to not allowing char particles having d = 30 μm or more to accompany the pyrolysis gas as much as possible.

Comparison of char particles contained in the pyrolysis gas in the prior art and the present invention is as follows.
1) In the present invention, the maximum value of N is a smaller particle diameter than before. From this,
2) Compared with the same Γ, the present invention has a smaller d than in the prior art.
3) In addition, when compared with the same d, the present invention has a larger Γ than before. This is due to the average reduction in the particle diameter of the char particles entrained in the pyrolysis gas by averagely reducing the flow rate of the pyrolysis gas in the outlet hopper.

  When the pyrolysis gas flows through the inside of a flow path such as a duct or a pipe, the gas flow velocity is not uniform over the entire cross section of the flow path, and changes in a complicated manner under the influence of the frictional resistance of the flow path and the gas itself. However, generally, the larger the cross-sectional area of the flow path, the lower the average flow velocity of the gas flowing inside.

  The reason why this can be reduced will now be described with reference to FIGS.

  The critical flow velocity Um entrained by the pyrolysis gas is extremely low with a particle diameter d of 1 μm or less, and continues to float in the pyrolysis gas stream, but is substantially proportional to d of 1 μm or more.

  As the flow rate of the pyrolysis gas increases as shown in FIG. 5, the upper limit of the particle diameter accompanying the gas flow increases. Since the volume and mass of the particles are proportional to the cube of the diameter, the amount of char entrained by the gas increases as the gas flow rate increases.

  In FIG. 4, the ratio of char particles of 30 μm or more contained in the pyrolysis gas in the kiln furnace is 60% or more, and the entrainment limit flow velocity with respect to the particle diameter is 0.1 m per second. From this, if Um is suppressed to 0.1 m or less per second, it means that char particles of 30 μm or more are not entrained in the flow of pyrolysis gas.

Next, FIG. 6 will be described.
FIG. 6 is an enlarged view of the ratio N of the number of particles to the diameter d of the char particles contained in the pyrolysis gas shown in FIG. 4 in the vicinity of d = 30 μm.

  When the average flow velocity of the pyrolysis gas stream is about 1 m per second, as shown in FIG. 5, most of the char particles of 30 μm or more are accompanied by the air stream. On the other hand, when the average flow velocity is about 0.1 m / sec, char particles of 30 μm or more fall to the exit hopper 20 side with little air flow. Thus, by lowering the average flow velocity of the pyrolysis gas stream, the average diameter of the char particles entrained in the stream can be reduced, and the total volume and total mass of the char particles can be reduced.

  As described above, when the pyrolysis gas flows inside a flow path such as a duct or a pipe, the particle diameters of char particles that can be accompanied by the gas differ depending on the difference in local flow velocity. However, if the gas flow velocity decreases on average, the char particle diameter accompanying the gas also decreases on average.

  This can reduce the char particles of 30 μm or more to 10% or less by the present invention employing the outlet hopper as described below.

  The char particles accumulated in the separation device 30 can be recovered in the direction of the inlet pipe 35 (upstream side) by rotating the ribbon screw 32 by the driving device 33. However, when the recovered particles are returned to the inlet pipe 35, the pyrolysis gas is again produced. 2 will be mixed and will be accompanied again.

  In order to prevent remixing of the char particles 4 separated and recovered by the separation device 30 and the pyrolysis gas 2 flowing into the separation device 30 in this way, the pyrolysis device of the present embodiment Separately, a return pipe 37 for discharging the collected char particles into the outlet hopper 20 is provided. On the other hand, the flow rate of the pyrolysis gas generated in the retort 11 in the outlet hopper 20 is highest at the upper end of the outlet opening of the retort 11.

  This is because the pyrolysis residue 3 generated by the retort 11 and the pyrolysis gas 2 are separated by gravity, so that the flow rate of the pyrolysis gas is maximized at the upper end position of the retort 11 opening. Therefore, if the opening of the return pipe 37 is extended to at least a position below the upper end of the outlet opening of the retort 11, it can be mixed with the pyrolysis gas at a relatively low flow rate and returned to the inside of the outlet hopper 20 to the pyrolysis gas. The re-entrainment of char particles can be reduced.

  Further, in the present invention, the outlet hopper horizontal cross-sectional area with respect to the maximum pyrolysis gas flow rate generated in the retort 11 is set so that the pyrolysis gas flow rate in the outlet hopper 20 is 0.1 m or less per second, and the pyrolysis gas is accompanied. The char particles are controlled to have a diameter of 30 μm or less. That is, the horizontal cross-sectional area of the outlet hopper 20 along the line H-H in FIG. 2 is set so that the maximum flow velocity is 0.1 m or less per second according to the amount of pyrolysis gas generated at the time of rating of the pyrolysis apparatus. It is set. In this way, by setting the cross-sectional area so that the maximum flow rate of the pyrolysis gas is 0.1 m or less per second, a particle distribution with an extremely small ratio of 30 μm or more can be obtained as shown in FIG. Compared with the conventional separation apparatus returned to the above, in the present invention in which a separate return pipe is provided, the particle ratio of 30 μm or more can be reduced, and the conventional problems can be solved.

  A second embodiment of the present invention will be described in detail with reference to FIGS. FIG. 7 is a cross-sectional view of main parts of a second embodiment of the thermal decomposition apparatus according to the present invention, and FIG. 8 is a cross-sectional view of main parts taken along the line BB in FIG. In addition, this embodiment is characterized in that the thermal decomposition apparatus includes a plurality of separation apparatuses, as compared to the first embodiment described above. Other substantially equivalent configurations are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 7, only one separation device on the near side is shown, and the separation device on the back side is omitted.

  The second embodiment shown in FIGS. 7 and 8 differs from the first embodiment of FIG. 1 in that two separation devices 30A and 30B are installed, and inlet pipes 35a and 35b are connected to each separation device. Two return pipes 37a and 37b are separately connected from each separation apparatus, and further, an opening / closing valve 40a is provided downstream of the outlet pipe 36a with respect to the separation apparatus 30A, and an opening / closing valve 41a is provided in the middle of the return pipe 37a. An opening / closing valve 40b is provided downstream of the outlet pipe 36b of 30B, and an opening / closing valve 41b is provided in the middle of the return pipe 37b, so that the pyrolysis gas discharged from each separator is sent to the combustion burner 50 via the junction pipe 42.

  In this embodiment, in order to prevent the char particles recovered by the separation devices 30A and 30B from mixing with the pyrolysis gas flowing into the separation device, for example, the char particles recovered by the separation device 30B are returned to the return pipe 37b. When discharging, after closing the downstream on-off valve 40b to stop the flow of pyrolysis gas, the return pipe on-off valve 41b is opened and discharged as shown by the arrow 4b, and the downstream on-off valve of one separation device 30A is discharged. 40a is opened, the on-off valve 41a of the return pipe 37a is closed, and the pyrolysis gas generated by the retort 11 is allowed to flow from the inlet pipe 35a as shown by the arrow 2a.

  When the char particles collected by the separation device 30A are discharged from the return pipe 37a, the four on-off valves 40a, 40b, 41a, 41b may be opened and closed this time. As described above, by providing a plurality of separation devices and return pipes, connecting an inlet tube, an outlet tube, and a return tube to each of the separation devices, and switching the flow of pyrolysis gas into the separation device with an on-off valve, The amount of char particles accompanying the gas can be reduced more than in the first embodiment.

  A third embodiment of the present invention will be described in detail with reference to FIGS. FIG. 9 is a cross-sectional view of main parts of a third embodiment of the thermal decomposition apparatus according to the present invention, and FIG. 10 is a cross-sectional view of main parts taken along the line CC of FIG. Note that this embodiment is different from the first embodiment described above in that the thermal decomposition apparatus includes a plurality of separation apparatuses, each of which does not have an inlet pipe, and has a pyrolysis gas from an opening in the middle of the return pipe. Inflow. Other substantially equivalent configurations are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 9, only one of the separating devices arranged in parallel is shown.

  The third embodiment shown in FIGS. 9 and 10 differs from the second embodiment shown in FIGS. 7 and 8 in that the return pipes 45a and 45b of the two separation devices 30C and 30D also serve as inlet pipes. It is. In each of these return pipes, openings 46a and 46b into which pyrolysis gas flows are formed at positions above the center of the outlet opening of the retort 11, and pyrolysis residue remains below the center of the outlet opening of the retort 11. Lower end openings 47a and 47b for discharging particles are formed, and the return pipe is constituted by a pipe having a plurality of openings. In the third embodiment, the density (gravity) of the char particles collected by the two separation devices is used to prevent mixing with the pyrolysis gas flowing into the separation device.

  That is, on the upstream side of the cylindrical main body 11, return pipes 45a and 45b having lower openings for discharging the char particles collected by the separation devices 30C and 30D to the outlet hopper 20 are connected. In the middle, openings 46 a and 46 b are formed for allowing the pyrolysis gas to flow into the cylindrical main body 11. Pyrolysis gas accompanied by char particles flows into the separators 30C and 30D from openings 46a and 46b formed in the middle of the return pipe, and the gas flow is swirled in the cylindrical main body 11 so that the char particles are removed. The pyrolysis gas after separation is supplied from the outlet pipe to the combustion burner. For this reason, it is not necessary to connect an inlet pipe to a cylindrical main body.

  The lower end opening of the return pipe extends to a position below the upper end of the outlet opening of the retort 11. In practice, the lower end opening of the return pipe extends to a position below the lower end of the exit opening of the kiln. By setting the position of the lower opening of the return pipe in this way, hot pyrolysis gas flows out to the outlet hopper along the upper edge of the outlet opening of the kiln. It is possible to prevent char particles falling in the return pipe of the apparatus from flowing into the cylindrical main body of the separation apparatus again on the rising airflow.

  In the present embodiment, two separation devices having the above-described configuration are arranged in parallel above the rotary kiln 10. On the two separation devices 30C and 30D, on-off valves 48a and 48b for stopping the flow of the pyrolysis gas into the cylindrical main body are connected to the respective outlet pipes 36c and 36d. With this configuration, it is possible to stop the flow of the pyrolysis gas into the separation device by closing one of the on-off valves. For example, when operating the drive device to recover the char particles, It is the structure which can stop inflow.

  For example, when the downstream on-off valve 48b is closed to stop the flow of pyrolysis gas and the char particles recovered by the separation device 30D are discharged, the char particles fall inside the return pipe 45b and fall as indicated by an arrow 4c. . At this time, the on-off valve 48a downstream of the other separation device 30C is opened, and the pyrolysis gas generated in the retort 11 can flow from the opening 46a of the return pipe 45a as shown by the arrow 2b. When the char particles recovered by the separation device 30C are discharged from the return pipe 45a, the two on-off valves 48a and 48b may be reversed in opening and closing.

  The reason why the char particles discharged by the separation device 30D fall inside the pipe of the return pipe 45b is that the density and gravity of the char particles are about 1000 times larger than the gas, and the pyrolysis gas is dropped when the char particles are dropped. Part of the char recovered by the flow of gas is again entrained in the pyrolysis gas, but the rate is small. The reason why the pyrolysis gas can flow through the opening 46a as shown by the arrow 2b is that the frictional resistance is large by the length of the pipe of the return pipe 45a, so that it easily flows from the opening in the middle. . In order to do so, it is necessary to set the areas of the openings 46a and 46b to be larger than the areas of the lower end openings of the return pipes 45a and 45b.

  Further, the openings 46a and 46b are provided above the center of the outlet opening of the retort 11, and the lower end openings of the return pipes 45a and 45b are provided below the center of the outlet opening of the retort 11, thereby returning the return pipe. Mixing of the char particles discharged from 45a and 45b and the pyrolysis gas flowing through the openings 46a and 46b can be prevented.

  As described above, the return pipes 45a and 45b having a plurality of openings are provided so as to serve both as the return pipe and the inlet pipe of the separation devices 30C and 30D, and the inflow of the pyrolysis gas is performed by the on-off valve connected to these return pipes. In addition to reducing the amount of char particles entrained in the pyrolysis gas, the costs of the return pipes 37a and 37b and the on-off valves 41a and 41b of the second embodiment can be reduced.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, an example of a ribbon screw was shown as a swirl vane arranged in the cylindrical main body of the separation device, but a swirl flow is generated in the pyrolysis gas passing through the inside of the cylindrical main body, and adhered to the cylindrical main body. Other coiled swirl blades may be used as long as they have a function of stripping off the char particles. Moreover, although the example of the rotary kiln was shown as a kiln which thermally decomposes waste, you may use a fixed kiln instead of a rotary type.

  As an application example of the present invention, the present invention can also be applied to the use of a thermal decomposition apparatus that uses this thermal decomposition apparatus to thermally decompose waste other than waste.

Sectional drawing which shows the principal part structure of one Embodiment of the thermal decomposition apparatus which concerns on this invention. AA sectional view taken on the line AA of FIG. The principal part perspective view which shows the ribbon screw of a separation apparatus. FIG. 1 is a graph showing the proportion of char particles entrained in a pyrolysis gas, for explaining the first embodiment shown in FIG. 1, and (a) is a diagram showing the proportion of the number of particles normalized by the maximum proportion; ) Is a diagram showing the ratio of (a) accumulated from the smaller one. The figure which shows the limit pyrolysis gas flow velocity with the char particle for description of 1st Embodiment shown in FIG. The figure which shows the particle | grain ratio of the char particle which can flow out accompanying thermal decomposition gas for description of 1st Embodiment shown in FIG. Sectional drawing which shows the principal part which shows 2nd Embodiment of the thermal decomposition apparatus which concerns on this invention. FIG. 8 is an essential part cross-sectional view taken along line BB in FIG. Sectional drawing which shows the principal part which shows 3rd Embodiment of the thermal decomposition apparatus which concerns on this invention. FIG. 10 is an essential part cross-sectional view along the line CC in FIG. 9;

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Waste, 2 ... Pyrolysis gas, 3 ... Pyrolysis residue (char), 4 ... Pyrolysis residue particle (char particle), 5 ... Pyrolysis gas from which pyrolysis residue particle | grains were collect | recovered, 6 ... Combustion gas, 7 ... Combustion gas after heating, 8 ... Exhaust gas, 10 ... Rotary kiln, 11 ... Retort, 12 ... Jacket, 20 ... Outlet hopper, 30, 30A, 30B, 30C, 30D ... Separation device, 31 ... Cylindrical body, 32 ... Ribbon screw (swirl vane) 33 ... drive device for separation device, 34 ... inner flow path of swirl vane, 35, 35a, 35b ... inlet pipe, 36, 36a, 36b, 36c, 36d ... outlet pipe, 37, 37a, 37b ... return pipes, 40a, 40b, 48a, 48b ... open / close valves (switching valves) of the separation device, 41a, 41b ... open / close valves connected to the return pipes, 45a, 45b ... return pipes also serving as inlet pipes, 46a, The upper opening of 6b ... return pipe, 42 ... merging pipe, 50 ... combustion burner, 60 ... heat exchanger

Claims (6)

A kiln that pyrolyzes waste to generate pyrolysis gas and pyrolysis residue, and discharges pyrolysis residue generated in the kiln to an outlet hopper and pyrolysis residue particles accompanying the pyrolysis gas A thermal decomposition apparatus comprising a separation device for recovering
The separation device includes a cylindrical main body that allows the pyrolysis gas to pass through, an inlet pipe that allows the pyrolysis gas generated in the kiln to flow into the cylindrical main body, and an opening that opens to the cylindrical main body on the downstream side of the inlet pipe. And a return pipe for discharging the pyrolysis residue particles to the outlet hopper. A kiln that pyrolyzes waste to generate pyrolysis gas and pyrolysis residue, and discharges pyrolysis residue generated in the kiln to an outlet hopper and pyrolysis residue particles accompanying the pyrolysis gas A thermal decomposition apparatus comprising a separation device for recovering
The separation apparatus includes a cylindrical main body through which pyrolysis gas passes, and a return pipe having a lower opening that discharges the pyrolysis residue particles connected to the cylindrical main body to the outlet hopper. And
An opening for allowing the pyrolysis gas generated in the kiln to flow into the cylindrical main body is formed in the upper portion of the return pipe.   The separation device includes a spiral blade wound in a spiral shape inside the cylindrical main body, allows pyrolysis gas to pass through the cylindrical main body, and remains in the pyrolysis by the swirl flow formed by the swirl blade. 3. The thermal decomposition apparatus according to claim 1, wherein particles are separated and deposited, and the deposited pyrolysis residue particles are recovered by peeling off the swirl blades.   The thermal decomposition apparatus according to any one of claims 1 to 3, wherein a lower end opening of the return pipe is extended to a position lower than an upper end of an outlet opening of the kiln.   The pyrolysis device includes a plurality of the separation devices, and each of the plurality of separation devices includes an on-off valve that stops inflow of the pyrolysis gas, and during the recovery of the pyrolysis residue particles, the separation is performed. The pyrolysis apparatus according to any one of claims 1 to 4, wherein an inflow of pyrolysis gas to the apparatus is stopped.   The flow path cross section of the outlet hopper continuous with the kiln is set so that the maximum flow rate of the pyrolysis gas at the outlet opening of the kiln is 0.1 m or less per second. The thermal decomposition apparatus as described in.

Images