JP2007269975A - Waste gasifier - Google Patents

Abstract

A packed bed waste gasifier is provided.
A waste gasifier according to the present embodiment includes a vertical gasifier 1 having an inlet 9 into which waste and incombustible pellets are placed at the top of the furnace, and the gasifier 1 An oxidant supply means for supplying an oxidant from below to the packed bed of waste and incombustible pellets, a gas outlet 11 for discharging the generated gas from above the gasifier 1, and a combustion residue from the bottom of the gasifier 1 And an extraction device 15 for extracting non-combustible pellets. Here, the extraction device 15 includes a rotary shaft 13 projecting from the bottom surface of the gasification furnace 1 into the furnace, a horizontal axis spaced apart from the bottom surface of the furnace, and a rotary shaft having a central portion as a rotation center. A rotary table 63 mounted on the rotary table 63, a plurality of blades 65 projecting radially from the rotation center toward the outer periphery on the upper surface of the rotary table 63, and the outer periphery of the rotary table 63. A combustion residue formed below and a discharge passage 19 for incombustible pellets are provided.
[Selection] Figure 1

Description

  The present invention relates to a waste gasifier that processes waste using a moving bed gasifier.

  As a method for treating waste, the waste is put into a gasification furnace together with non-combustible pellets (for example, pumice) to form a packed bed, and an oxidant gas is supplied from the bottom to cause partial combustion. Has proposed a moving bed gasification furnace that gasifies waste by forming a combustion zone, a pyrolysis zone, and a drying zone (see, for example, Patent Document 1).

  According to this, while the waste of the drying zone is dried by the heat of the pyrolysis gas generated in the pyrolysis zone, the fly ash contained in the pyrolysis gas and the like in the process of the pyrolysis gas rising up the drying zone. Since it is removed, a relatively clean pyrolysis gas can be obtained. In addition, since the waste packed bed in the furnace contains non-combustible pellets, for example, the flowability of an oxidant gas or the like can be improved.

  On the other hand, a rotary extraction device for extracting combustion residues and incombustible pellets is installed at the bottom of such a gasification furnace. In this extracting device, for example, a plurality of rotating blades extending in the horizontal direction with a certain distance from the table are attached to a rotating shaft protruding from the center of a fixed flat table. By rotating the rotary blade on the table, the waste combustion residue and non-combustible pellets can be cut out in the radial direction and discharged from the discharge port (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2004-2552 JP 2003-335422 A

  However, when the extractor of Patent Document 2 is used, for example, fine powder having a predetermined particle size flowing down from the packed bed of the gasification furnace bites into the gap between the table and the rotary blade, thereby increasing the rotational load of the rotary blade. Therefore, there is a risk of preventing stable discharge such as deforming the rotary blade.

  The cause of this fine powder is not necessarily clear, but, for example, a part of the non-combustible pellets due to rubbing when cutting out the non-combustible pellets from the supply device, drop impact at the time of entering the furnace, thermal deterioration due to repeated use, etc. Crushing is considered. Further, since the size of the fine powder generated in this way is not constant, for example, even if the interval between the table and the rotary blade is adjusted, the biting cannot be completely eliminated.

  This invention makes it a subject to extract a combustion residue and a nonflammable pellet stably from a mobile gasifier.

  In order to solve the above-described problems, the present invention provides a vertical gasification furnace having an inlet into which waste and incombustible pellets are introduced at the top of the furnace, and waste and incombustible pellets in the gasification furnace. An oxidant supply means for supplying an oxidant to the packed bed from below, a gas outlet for discharging the generated gas from above the gasifier, and an extraction device for extracting combustion residues and non-combustible pellets from the bottom of the gasifier In the waste gasifier, the extraction device has a rotating shaft projecting into the furnace from the bottom surface of the gasification furnace, and extends in the horizontal direction at a distance from the bottom surface of the gasification furnace, and the center portion is the center of rotation. As a flat plate-like rotary table attached to the rotary shaft, a plurality of blades formed radially on the upper surface of the rotary table from the center of rotation toward the outer periphery, and formed integrally with the rotary table, and below the outer periphery of the rotary table Combustion residue formed on And characterized in that it comprises a discharge flow path of the non-combustible pellets.

  According to this configuration, since the rotary table and the plurality of blades rotate as a unit, fine powder or the like is mixed in the gap between them and the rotational load of the blades is not increased, and combustion residues, non-combustible pellets, etc. It can be extracted stably. Moreover, although the load of the packed bed in a furnace is applied to a table surface, since the rotational load of a blade | wing can be made small compared with the case where a blade | wing is rotated relatively with respect to a table, damage to a blade | wing can be suppressed. In addition, by rotating the turntable itself, the shear region of the packed bed is increased, and a sufficient discharge capacity can be ensured.

  In this case, the extraction device is formed such that the blades are curved in the direction opposite to the rotation direction of the rotary table, and the radius of curvature decreases from the rotation center toward the tip. According to this, with the rotation of the rotary table, the discharged material can be efficiently guided to the discharge channel along the curved blade.

  Further, the extraction device is formed such that the blades extend outside the outer periphery of the rotary table, and the tip thereof is connected to a scraper disposed in the discharge flow path. Thereby, the discharge material cut out in the discharge channel can be guided to a predetermined discharge port by the scraper.

  According to the present invention, combustion residues and incombustible pellets can be stably extracted from a mobile gasifier.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of a waste gasifier according to the present invention. Here, although the waste gasification apparatus of this embodiment is used suitably for gasification of a general waste, an industrial waste, biomass, etc., it is not limited to this.

  As shown in the figure, the waste gasifier 1 of the present embodiment (hereinafter simply referred to as a gasifier) is, for example, a state in which waste is appropriately dried on the top of a cylindrical vertical container 3. And a hopper 6 for storing non-combustible pellets (for example, spherical calcined pumice, φ20 to 25 mm) used by mixing with waste in the furnace. Double dampers 8 and 10 are provided at the inlets of the hopper 5 and the hopper 6, respectively. For example, the waste is conveyed by the screw conveyor 7 and supplied into the container 3 from the input port 9, while the non-combustible pellet is supplied from the input port 9 into the container 3 by the rotary feeder 12.

  The gasification furnace 1 has a gas outlet 11 for discharging a generated gas (pyrolysis gas) on the top side wall, and a gasifying agent for supplying combustion oxidant gas (air or oxygen, etc.) and water vapor to the bottom. A supply port 13 is provided. The gasifying agent supply port 13 is formed at the tip of the rotary shaft 17 of the rotary extraction device 15 that forms the bottom of the gasification furnace 1, for example. The oxidant gas and water vapor that flow through the rotary shaft 17 and are supplied into the furnace from the gasifying agent supply port 13 are supplied radially into the gasification furnace 1. The rotating shaft 17 of the extraction device 15 is connected to the motor 21 and, as the rotating shaft 17 rotates, blades described later cut out combustion residues of wastes in the radial direction and discharge them from the discharge port 19. Yes. Note that the gasifying agent supply port 13 is not limited to the present embodiment as long as the oxidizing agent and the water vapor are uniformly supplied in the horizontal cross-sectional direction of the gasification furnace 1, for example.

  A steam supply nozzle 18 for supplying steam into the furnace is attached to a set height position of the furnace wall, that is, a lower part of a formation position of a combustion zone 51 described later. For example, the water vapor supply nozzles 18 are arranged at equal intervals in the circumferential direction at the same height position on the furnace wall.

  The gasification furnace 1 is provided with a plurality of temperature sensors 23 at predetermined intervals in the furnace height direction of the furnace wall, and one of the temperature sensors 23 is disposed at the same furnace height position as the steam supply nozzle 18. The A plurality of level sensors 25 for detecting the height of the packed bed are attached to the furnace wall above the temperature sensor 23 arranged at the uppermost stage in the furnace height direction. Although not shown, a pressure sensor for detecting the pressure in the upper space 27 of the packed bed is attached to the furnace wall above the level sensor 25.

  Next, operation | movement of the gasification furnace 1 comprised in this way is demonstrated. First, at the time of start-up, incombustible pellets are supplied into the gasifier 1 from the inlet 9. This incombustible pellet is for improving the flowability of an oxidant or the like supplied into the furnace. When a predetermined amount of incombustible pellets is supplied, waste that has been appropriately dried and pulverized is introduced into the gasification furnace 1 from the inlet 9. The waste thrown into the furnace is filled into the furnace in a state of being uniformly mixed with the noncombustible pellets to form a packed bed.

  Next, the gasifier 1 filled with waste is ignited by supplying an oxidizing agent from the gasifying agent supply port 13 and blowing hot air (for example, 400 ° C. or more) from the hot air generator 14 for ignition. Let Then, the supply amount of the oxidant is adjusted, the waste is partially burned, and a combustion zone is formed in the packed bed. When the waste is pyrolyzed by the combustion heat of this combustion zone, pyrolysis gas is generated, and this pyrolysis gas rises in the gasification furnace 1 through the gap between the waste and is discharged from the gas outlet 11. Discharged.

In a steady state where the partial combustion and thermal decomposition of the waste are stable, a stable combustion zone 51 is formed in the vicinity of the bottom of the furnace, a thermal decomposition zone 53 is formed on the upper portion, and a waste drying zone 55 is further formed on the upper portion. Is formed. For example, when the waste reaches about 300 ° C. or more, it is thermally decomposed. Therefore, the region of the packed bed of waste exceeding the temperature range becomes the thermal decomposition zone 53. In the pyrolysis zone 53, the waste is pyrolyzed to generate combustible pyrolysis gas and carbon (char). The char generated here flows down to the combustion zone 51 and burns, and the temperature of the combustion zone 51 becomes about 1000 ° C. or higher. Further, a part of the char generated in the thermal decomposition zone 53 reacts with the water vapor supplied to the combustion zone 51 and is converted into CO and H ₂ . The flow rate of the oxidant and water vapor supplied into the furnace is adjusted so that most of the produced char becomes combustion gas and water gas.

  The generated gas obtained by mixing the pyrolysis gas and the water gas generated in this manner passes through the drying zone 55 and dries the waste in the process of flowing through the gap between the wastes in the upper layer. The generated gas is reduced in temperature (for example, about 200 ° C.) by drying the waste, and is discharged from the gas outlet 11 through the upper space 27 formed at the top of the gasification furnace 1. Even if fly ash generated in the combustion zone 51 accompanies the product gas, the waste layer filled in the dry zone 55 collects as a filter, so that the fly ash flowing out from the gas outlet 11 is collected. The amount of ash can be reduced.

  On the other hand, the waste dried in the drying zone 55 gradually moves to the thermal decomposition zone 53 and undergoes thermal decomposition treatment, and then moves to the combustion zone 51 where it is thermally decomposed and burned to become ash (combustion residue). These flow down the cooling zone 57 formed in the lower layer of the combustion zone 51, and are cut out to the discharge port 19 together with the non-combustible pellets by the rotation of the rotary extraction device 15 and discharged outside the furnace. The non-combustible pellets discharged to the outside of the furnace are returned to the hopper 6 and repeatedly used.

  In this way, the waste in the packed bed moves downward when the extraction device 15 extracts the waste from the bottom. On the other hand, the furnace height position at which the combustion zone 51 and the pyrolysis zone 53 are formed is adjusted to a height range set by, for example, the waste extraction speed and the oxidant supply speed.

  When the gasification furnace 1 is started up, the char generated by pyrolyzing the waste is combusted in the combustion zone 51, but a part of the char passes through the combustion zone 51 and remains in the cooling zone without being burned. Since 57 may flow down, water vapor reaction is performed by supplying water vapor in order to stabilize the gasification efficiency of the waste from the start-up.

  By the way, incombustible pellets supplied into the gasification furnace 1 may be partially crushed due to, for example, rubbing when cutting out from the rotary feeder 12, drop impact when being charged into the furnace, thermal deterioration due to repeated use, and the like. is there. The crushed crushed pieces flow down along with the waste in the furnace, and are usually discharged out of the furnace together with combustion residues. However, in the conventional extraction device, a plurality of rotary blades extending in the horizontal direction with a set interval are attached to the rotary shaft protruding from the center of the flat table fixed to the furnace bottom, The rotary blade is configured to rotate relative to the table surface. For this reason, for example, when a non-combustible pellet fragment having a predetermined size or an incombustible material contained in the waste moves to the gap between the table and the rotary blade, the rotary blade is bitten and crushed. There is a risk that the rotation of the rotating blade may be hindered or the rotating blades may be deformed.

  Hereinafter, the configuration of the extraction device 15 of the present embodiment will be described with reference to the drawings.

  FIG. 2 is a longitudinal sectional view showing a basic configuration of the extraction device of the present embodiment. FIG. 3 is a plan view of the extraction device of the present embodiment, and FIG. 4 is a longitudinal sectional view showing a part of the extraction device of the present embodiment.

  The extraction device 15 of the present embodiment extends in a horizontal direction with a set interval from the rotary shaft 17 projecting from the bottom plate 61 at the bottom of the gasification furnace 1, with the center portion as the center of rotation. The rotary table 63 has a disk-like rotary table 63 attached to the rotary shaft 17, and a plurality of blades 65 projecting radially from the vicinity of the rotary shaft 17 to the outer periphery of the table are formed on the rotary table 63. The A discharge channel 67 is formed in the circumferential direction below the outer periphery of the rotary table 63, and a part thereof communicates with the discharge port of the gasification furnace 1.

  The blades 65 of the present embodiment are continuously formed along the upper surface of the rotary table 63. For example, a space (gap) having a predetermined shape is formed in a part of the connection portion between the blades 65 and the rotary table 63. May be. That is, since the blade 65 rotates integrally with the rotary table 63, even if such a space is formed, the blade 65 does not bite. Therefore, the rotational load of the blades 65 is not increased, and incombustible pellets and the like can be withdrawn stably without being crushed.

  Further, the rotary table 63 is loaded on the entire upper surface of the packed bed in the furnace, but the rotational load of the blade 65 can be reduced as compared with the conventional configuration in which the blade is rotated relative to the table surface. Therefore, breakage of the blade 65 can be suppressed. Further, since the rotary table itself is rotated, the shear region of the packed bed is increased, and a sufficient discharge capacity can be ensured. In the present embodiment, the inner peripheral structure of the bottom region of the container 3 is increased in diameter so that the outer diameter of the rotary table 63 is larger than the outer diameter of the bottom plate 61 and the inner diameter of the container 3 (region above the bottom). It forms so that a granular material may not penetrate | invade in the clearance gap between the base 61 and a turntable.

  Here, it is not necessary that the outer peripheral edge of the blade 65 reaches the outer peripheral edge of the turntable 63. However, in order to efficiently guide the combustion residue, non-combustible pellets, and the like to the discharge passage 67, the present embodiment. As described above, it is preferable that the outer peripheral edge of the blade 65 reaches the outer peripheral edge of the rotary table 63.

  Next, a specific shape of the blade 65 will be described. The blades 65 may be linearly formed from the vicinity of the rotary shaft 17 toward the outer peripheral edge of the rotary table 63, but as shown in FIG. 3, for example, the rotation direction of the rotary table 63 (arrow in the figure). May be formed so that the radius of curvature decreases from the rotary shaft 17 toward the tip side. According to this, with the rotation of the turntable 63, combustion residues, non-combustible pellets and the like can be easily moved to the outer peripheral side along the curved blades 65, and can be efficiently discharged.

  In addition, a scraper 69 is disposed in the discharge channel 67, and the tip of the blade 65 extends downward from the outer peripheral edge of the rotary table 63 and is connected to the scraper 69. Here, the tip of the blade 65 is connected to a rotating ring 71 formed in the discharge channel 67 in the circumferential direction. Scrapers 69 are connected at equal intervals in the circumferential direction of the rotating ring 71. For example, as shown in FIG. 4, the scraper 69 is configured by connecting a scraper 73 below a support member 72 that is inclined toward the outer peripheral side of the discharge channel 67. According to this, with the rotation of the rotary table 63, the plurality of blades 65 and the scraper 69 rotate together to efficiently remove the combustion residue, incombustible pellets, and the like that have fallen into the discharge passage 67 to the discharge port 19. Can lead.

  Note that the blade 65 has a uniform protrusion amount (thickness) protruding from the table surface from the vicinity of the rotation shaft 17 of the rotary table 63 to the outer peripheral edge. Good. Moreover, the protrusion amount (maximum amount) of the blades 65 is appropriately set so as to be, for example, approximately half of the spherical diameter of the non-combustible pellets to be used or smaller.

  The blades 65 may be formed integrally with the rotary table 63, or the blades 65 may be connected to the upper surface of the rotary table 63 by welding.

  Although the present invention has been described in detail with reference to the illustrated embodiments, the present invention is not limited only to these embodiments, and various modifications can be made without departing from the technical idea of the present invention. Needless to say, it can be done.

It is a block diagram which shows the principal part of the waste gasification apparatus of this invention. It is a longitudinal cross-sectional view which shows the basic composition of the extraction apparatus of this embodiment. It is a top view which shows the extraction apparatus of this embodiment. It is a fragmentary longitudinal cross-sectional view of the extraction apparatus of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification furnace 5,6 Hopper 11 Gas discharge port 15 Extraction apparatus 17 Rotating shaft 19 Discharge port 61 Bottom board 63 Rotary table 65 Blade

Claims (3)

A vertical gasification furnace having an inlet into which waste and incombustible pellets are introduced at the top of the furnace, and supply of oxidant from below to the packed bed of waste and incombustible pellets in the gasification furnace Waste gasification comprising: an oxidant supply means for discharging; a gas discharge port for discharging the generated gas from above the gasification furnace; and an extraction device for extracting the combustion residue and the non-combustible pellets from the bottom of the gasification furnace In the device
The extracting device is attached to the rotating shaft with a rotating shaft protruding into the furnace from the furnace bottom of the gasification furnace, extending in a horizontal direction with a space from the furnace bottom and having a central portion as a rotation center. A flat plate-shaped rotary table, a plurality of blades that are radially formed on the upper surface of the rotary table from the center of rotation toward the outer periphery, and formed integrally with the rotary table, and below the outer periphery of the rotary table. A waste gasifier comprising the combustion residue formed and a discharge passage for the non-combustible pellets. 2. The disposal according to claim 1, wherein the extraction device is formed such that the blade is curved in a direction opposite to a rotation direction of the rotary table, and a curvature radius decreases from the rotation center toward the tip. Product gasifier. The said extraction device is characterized in that the blade extends outside the outer periphery of the rotary table and the tip thereof is connected to a scraper disposed in the discharge flow path. The waste gasifier according to 1 or 2.

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