JP5766516B2 - Cylindrical fluidized bed furnace - Google Patents

Description

  The present invention relates to a cylindrical fluidized bed furnace for treating waste, and in particular, a cylindrical furnace main body having a circular horizontal cross section of the hearth and an incombustible material provided eccentrically from the center of the cylindrical furnace main body. The present invention relates to a cylindrical fluidized bed furnace having a discharge port.

  Conventionally, a fluidized bed furnace has been used as a waste treatment apparatus. A fluidized bed furnace uses a large heat capacity of a fluid medium (sand, etc.), throws waste into a fluid medium heated to a high temperature, and allows the waste to be dried, pyrolyzed and burned in a short time. It is used in fluidized bed incinerators and fluidized bed gasification and melting furnaces (consisting of a fluidized bed gasification furnace and a melting combustion furnace). In a fluidized bed furnace, heat exchange is performed quickly between a fluid medium that flows violently and the object to be processed, so that the heat transfer speed is fast and the reaction is performed quickly. The material movement in the vertical direction is easy to be performed, but the material movement in the horizontal direction is difficult to be performed. Therefore, in the application of the fluidized bed furnace to the waste treatment, first, a homogeneous and easily dispersible material such as sludge is used as an object and is supplied uniformly to the hearth. When solid waste such as municipal waste is used as a treatment target, a method is used in which the treatment target is crushed in advance and uniformly supplied to the hearth.

  As a fluidized bed furnace, there is a cylindrical fluidized bed furnace in which the horizontal cross section of the hearth is circular, that is, the furnace is cylindrical, and an incombustible discharge port is provided at the center of the hearth. Since it has the simplest and cylindrical shape, thermal stress is evenly distributed, and there is an advantage that the durability of the refractory material and the like is high. In this cylindrical fluidized bed furnace, fluidized air is not supplied above the incombustible discharge port in the center of the hearth, so that it is a so-called fixed bed. Therefore, when waste is taken into this fixed bed, the fluidized medium is not fluidized, so heat exchange between the fluidized medium and the object to be treated is only heat conduction, and heat exchange is not performed quickly. The thermal decomposition of the object is difficult to proceed, and since there is no supply of fluidized air, the thermal decomposition residue (char) is not combusted by the fluidized air. If it does so, it will be mixed with incombustibles from the incombustible discharge port, and the pyrolysis residue will be discharged, the combustion efficiency will be reduced, and dioxins are included in the pyrolysis residue (char), so dioxins of incombustibles There is a disadvantage that the concentration becomes high. In order to prevent this inconvenience, the amount of fluidized air around the incombustible discharge port is increased, and the fixed layer is made the minimum area just above the incombustible discharge port, so that the processing object and pyrolysis residue (char) are incombustible. The product is prevented from being discharged from the outlet. In other words, a so-called bubbling fluidized bed is employed that allows uniform fluidization throughout the hearth.

  In the above-described cylindrical fluidized bed furnace, the object to be treated is supplied to the central part of the furnace, and the object to be treated is swallowed into the fluid medium gradually descending in the periphery of the horizontal cross section of the circular hearth. A thermal reaction is performed, and the incombustible material is discharged together with the fluid medium from the incombustible material discharge port. In a cylindrical fluidized bed furnace, in order to supply the object to be processed to the center of the hearth, the object to be processed is supplied from the center of the hearth, or the object to be processed falls smoothly to the upper part of the hearth and the center of the hearth A chute that is supplied to the section was provided.

  However, if it is supplied from the furnace ceiling, the required height of the facility will be high, and even if it is supplied from the side wall of the furnace with a chute aiming at the center of the hearth, the waste to be treated consists of various components. In waste, the drop position varies depending on the shape and specific gravity of various components, and it is difficult to supply waste evenly to the hearth and take it into the fluidized bed, and the supply position of waste tends to be biased. The region where the thermal reaction takes place in the hearth tends to be biased. In order to supply the object to be treated evenly from the periphery of the hearth, it is impractical to arrange a large number of dust supply devices around the furnace. For this reason, it is difficult to treat the object to be treated in the whole area of the hearth, and the waste is apt to be biased toward a part of the hearth.

  On the other hand, municipal wastes and other objects to be treated contain incombustible materials such as stones, rubble, ceramic pieces and metals, and the stable discharge of these incombustible materials from the fluidized bed fluidizes the fluidized medium. It is essential to maintain a stable fluidized bed. For this reason, by supplying a fluidizing gas to a fluid medium made of sand or the like so that the mass velocity in the peripheral part is larger than that in the central part, a moving bed where the fluid medium settles and diffuses in the central part of the furnace Forming a fluidized bed in which the fluidized medium is actively fluidized in the periphery of the furnace, circulating the fluidized medium between the moving bed and the fluidized bed, and moving the fluidized medium horizontally in the fluidized bed. An accelerated so-called swirling fluidized bed furnace has been developed (see Patent Document 1).

  In a swirling fluidized bed furnace, the object to be treated is taken into the circulating flow of the fluid medium to cause a thermal reaction in the hearth, and the incombustible material is discharged from the incombustible discharge port in the periphery of the furnace by the circulating fluid medium. It discharges stably. In order to discharge incombustibles using a circulating flow of a fluidized medium, a fluidized bed furnace having a rectangular horizontal cross section as described in Patent Document 1 is often used.

Japanese Examined Patent Publication No. 62-5242

  As described above, the fluidized bed furnace can be roughly divided into a cylindrical fluidized bed furnace in which the horizontal cross section of the hearth is circular and a fluidized bed furnace in which the horizontal cross section of the hearth is rectangular. Cylindrical fluidized bed furnaces are the simplest structurally and have the advantage of being evenly distributed in thermal stress and being highly durable, such as refractory materials. It is difficult to take in, the supply position of the waste tends to be biased, and the region where the thermal reaction is performed in the hearth tends to be biased, and the waste processing tends to be biased to a part of the hearth There are drawbacks. On the other hand, the circulating flow type fluidized bed furnace with a rectangular horizontal cross section of the hearth has the disadvantage that it is structurally complex and thermal stress tends to concentrate on the corners, etc. Can be discharged stably from the fluidized bed.

The inventors pay attention to the structurally superior point of the cylindrical fluidized bed and pay attention to the point that the incombustible material in the swirling fluidized bed furnace can be discharged stably from the fluidized bed. The following knowledge was acquired by trying to apply the circulating flow of a fluid medium to a bed furnace. That is, when applying a circulating flow to a cylindrical fluidized bed furnace with an incombustible discharge port in the center of the hearth, a moving bed in which the fluid medium settles and diffuses is formed in the center of the furnace and flows in the periphery of the furnace When a fluidized bed in which the medium is actively fluidized is formed and waste is supplied to the central part of the furnace, unreacted waste is discharged from the incombustible discharge port together with the fluidized medium of the moving bed that settles and diffuses in the central part of the furnace There is a problem that a large amount is discharged. In order to avoid this, a moving bed in which the flowing medium settles and diffuses is formed in the periphery of the furnace, a fluidized bed in which the flowing medium is actively fluidized is formed in the center of the furnace, and waste is formed in the center of the furnace. The waste is transported to the periphery of the furnace by the fluidized medium that moves radially from the center of the furnace to the periphery of the furnace in the upper part of the fluidized bed, and is swallowed by the moving bed in the periphery of the furnace. The thermal reaction takes place within.
However, when the waste supplied to the central part of the furnace is conveyed radially by the fluid medium moving from the central part of the furnace to the peripheral part of the furnace, it is difficult for the waste to be evenly distributed in the circumferential direction, There is a problem that the region where the thermal reaction is performed tends to be biased.

Based on the above findings, the present inventors have repeatedly conducted tests for optimizing waste supply conditions and furnace bed fluidization conditions in a cylindrical fluidized bed furnace, thereby disposing of waste by circulating flow of a fluid medium. It is difficult to disperse the material evenly from the fluidized bed in the central part of the furnace to the moving bed in the peripheral part of the furnace so that it can be swallowed evenly on the entire surface of the moving bed. It was found that supplying the waste and swallowing the waste is the optimum waste supply condition. In a fluidized bed furnace with a circular horizontal cross section, the fluidized medium must move radially inward and outward between the moving bed in the periphery of the furnace and the fluidized bed in the center of the furnace. Therefore, when the fluid medium is diffused from the vicinity of the center of the circle in the circumferential direction of the circle, it is difficult to evenly diffuse the fluid medium, and it is difficult to form a uniform circulating flow over the entire surface of the furnace. When forming a circulating flow, we found that a fluidized bed furnace with a circular horizontal cross section with the same area in the radial direction with the moving bed and fluidized bed radially centered around the incombustible discharge port is optimal. Invented the invention.
That is, according to the present invention, the position of the incombustible discharge port of the hearth is eccentric from the axial center of the cylindrical furnace body, and the waste is supplied from the waste supply port of the furnace wall far from the incombustible discharge port. By forming a circulating flow of the fluidized medium between the waste supply part of the hearth and the incombustible discharge port, it is not necessary to supply the waste uniformly to the hearth, and the thermal reaction takes place in a wide range within the fluidized bed. An object of the present invention is to provide a cylindrical fluidized bed furnace capable of preventing char from being mixed into incombustible materials.

In order to achieve the above object, a cylindrical fluidized bed furnace according to the present invention is a fluidized bed furnace for treating waste, and a cylindrical furnace body having a circular horizontal cross section is disposed at the bottom of the furnace body. And a floor plate provided with a gas supply port for supplying a fluidizing gas and flowing a fluid medium, and provided at the bottom of the cylindrical furnace body, and arranged eccentrically from the axial center of the cylindrical furnace body A non-combustible material discharge port, and a waste supply port provided on a furnace wall on the opposite side of the non-combustible material discharge port across the axial center of the cylindrical furnace body, the waste supply port A difference is provided between the waste supply port side and the incombustible material discharge port side in the supply amount of fluidized gas ejected from the gas supply port provided in the floor plate between the furnace wall on a certain side and the incombustible material discharge port The fluidization speed on the non-combustible discharge port side is larger than the fluidization speed on the waste supply port side, Bed material to form a moving layer to settle on the sheet inlet side, the incombustible discharge port side to the fluidized medium forms a fluidized layer increases, the waste feed port across the axis of the cylindrical furnace body The fluidization speed between the furnace wall on the opposite side and the furnace wall on the opposite side and the incombustible material discharge port is equivalent to the large fluidization speed on the incombustible material discharge port side, and flows around the incombustible material discharge port. A bubbling fluidized bed in which the medium repeatedly moves up and down is formed .

  According to the present invention, it is possible to form a circulating fluidized bed having a large area between the waste supply part in the hearth just below the waste supply port and the incombustible discharge port. This circulating flow fluidized bed forms a fluidized bed having a substantially fan-like horizontal cross section, and the circulating flow of the fluidized medium between the moving bed in the periphery of the furnace and the fluidized bed in the center of the furnace in the substantially sectorized fluidized bed. The fluidized medium is not diffused in the circumferential direction of the circle when forming the fluid, and the fluidized medium circulates like a fluidized bed having a rectangular horizontal section. Since a moving bed in which the fluid medium moves from the upper side to the lower side at a relatively slow speed is formed immediately below the waste supply port, the waste supplied from the waste supply port to the fluidized bed is transferred to the moving bed. Can be swallowed immediately by the settling flow. When the waste is swallowed into the moving bed and moves downward together with the fluidized medium, the wastewater is dried and pyrolyzed by the heat of the fluidized medium, the moisture in the waste is evaporated, and the combustible in the waste is combusted. Combustible gas is generated from the minute and becomes a brittle pyrolysis residue. The pyrolysis residue includes incombustible materials and unburned materials (chars) that have become brittle by thermal decomposition. When the pyrolysis residue generated in the moving bed reaches the floor plate together with the fluidized medium, it goes to the fluidized bed along the inclined floor plate. The pyrolysis residue that has reached the fluidized bed peels off the unburned material (char) from the incombustible material by the fluidizing gas, and the unburned material (char) is peeled off from the incombustible material. Head to the outlet. At this time, since the incombustible discharge port is eccentric from the axial center of the cylindrical furnace body, it is possible to secure a moving distance for unburned material (char) to be peeled from the incombustible material, and the pyrolysis residue The incombustible material in the inside surely moves a certain distance of the fluidized bed, so that the unburned material (char) and the incombustible material can be appropriately separated. The incombustible material flows into the incombustible material discharge port together with a part of the fluidized medium and is discharged out of the fluidized bed furnace.

On the other hand, the unburned material (char) peeled from the incombustible material moves upward together with the fluidized medium that flows as the fluidizing gas is supplied. At this time, the unburned matter (char) is burned by the supplied fluidized gas, and the combustion medium is generated while heating the fluid medium, and the unburned matter (char) is conveyed to the gas. And particles of ash. In the fluidized bed, the temperature gradually rises as the unburned matter (char) burns, so the temperature rises proportionally from the bottom to the top. On the other hand, the fluid medium reaching the upper part of the fluidized bed is dispersed on the surface of the fluidized bed and swallowed by the settling flow of the moving bed. The fluidized medium is raised in the fluidized bed to a temperature at which waste can be properly pyrolyzed in the moving bed. The fluidized medium that has flowed into the moving bed receives the waste again supplied and repeats the thermal reaction in the moving bed and the fluidized bed.
According to the present invention, the horizontal cross section having a moving bed and a fluidized bed has a substantially circular fan-shaped circulating fluidized bed, and a bubbling fluidized bed on the opposite side of the region of the circulating fluidized bed across the incombustible discharge port. By increasing the amount of fluidized gas around the incombustible discharge port, the fixed layer is the minimum area directly above the incombustible discharge port, and waste and pyrolysis residue (char) are discharged into the incombustible discharge port. So that it will not be discharged from.

According to a preferred aspect of the present invention, the gas supply port provided in the floor plate between the furnace wall on the side where the waste supply port is located and the incombustible discharge port is connected to the gas supply port on the waste supply port side and non-combustible. It is characterized by being divided into two or more gas supply ports on the object discharge port side.
According to the present invention, the gas supply ports from the waste supply port side to the incombustible discharge port side are divided into two or more groups, and the flow of the fluidized medium is determined by the amount of gas ejected from the divided gas supply ports. By providing a difference in the conversion rate, the upward flow of the fluidized medium in the fluidized bed or the sedimentary flow of the fluidized medium in the moving bed can be adjusted more finely, and the incombustibility of the fluidized bed can be increased so that the thermal reaction of waste proceeds more. Movement of objects and settling in the moving bed takes place.

  According to a preferred aspect of the present invention, the gas supply port provided in the floor plate between the furnace wall on the side where the waste supply port is located and the incombustible discharge port is partitioned into an air box provided under the floor plate. It is characterized by partitioning by providing and dividing.

  According to a preferred aspect of the present invention, a fluid medium circulates between the moving bed and the fluidized bed in a furnace region between the furnace wall on the side where the waste supply port is located and the incombustible discharge port. A circulating flow is formed.

According to a preferred aspect of the present invention, the gas supply ports provided in the floor board are arranged on a concentric circle and a concentric arc centered on the incombustible discharge port.
According to the present invention, the fluidizing gas is ejected from the gas supply ports arranged on the concentric circles so as to give a substantially large fluidizing speed, and the fluid medium actively flows above the concentric circles of the floor plate. From the gas supply port that forms the fluidization zone and is arranged on the arc, the fluidizing gas is ejected so as to give a substantially small fluidization speed, and the fluid medium becomes relatively slow above the arc of the floor plate. A weak fluidization zone that flows at a speed is formed. Among the concentric circles, a strong fluidization region formed above a substantially semicircular portion adjacent to the arc and a weak fluidization region formed above the arc are present as a result of being weak. In the fluidization zone, a moving bed is formed in which the fluid medium moves from the upper side to the lower side at a relatively slow speed, and in the strong fluidization zone, a fluid bed in which the fluid medium moves from the lower side to the upper side is formed. Therefore, in the entire region where the weak fluidization zone and the strong fluidization zone are adjacent to each other, the fluidized medium is fluidized from the weak fluidization zone to the strong fluidization zone (moving bed to fluidized bed) at the bottom, and strong fluidization at the top. By moving from the zone to the weak fluidized zone (from the fluidized bed to the moving bed), a circulating flow is formed in which the fluid medium circulates between the weakly fluidized zone and the strong fluidized zone (moving bed and fluidized bed). .

According to a preferred aspect of the present invention, a waste supply device comprising a screw feeder is installed at the position of the waste supply port.
According to the present invention, since the waste supply device including the screw feeder that supplies the waste in a substantially horizontal direction is provided at the waste supply port provided in the cylindrical furnace wall, the waste is supplied from the center of the furnace ceiling. In addition, there is no need to provide a chute that allows the waste to fall smoothly and be supplied to the center of the hearth, and the overall height (height) of the facility can be reduced.

The present invention has the following effects.
(1) Since it is a cylindrical fluidized bed furnace, the structure is the simplest and the furnace can be easily manufactured, and the furnace wall has a cylindrical shape, so that the durability of the refractory is improved.
(2) A large-sized circulating fluidized bed can be formed between the waste supply part in the hearth just below the waste supply port and the incombustible discharge port. This circulating fluidized bed forms a fluidized bed with a substantially fan-like horizontal cross section, and in this fluidized bed with a substantially fanlike surface, the fluid medium circulates between the moving bed at the periphery of the furnace and the fluidized bed at the center of the furnace. When the flow is formed, the flowing medium does not diffuse in the circumferential direction of the circle, and the horizontal section becomes a circulating flow of the flowing medium similar to a rectangular fluidized bed, and the flowing medium flows from the periphery of the furnace toward the incombustible discharge port. Non-combustible materials can be discharged smoothly outside the furnace by the flow.
(3) Since a moving bed in which the fluid medium moves from the upper side to the lower side at a relatively slow speed is formed immediately below the waste supply port, the waste supplied to the fluidized bed from the waste supply port It can be swallowed immediately by the sedimentary flow of the moving bed. Therefore, it is not necessary to uniformly distribute the waste to the hearth, and the waste can be easily supplied.
(4) Since a waste supply device comprising a screw feeder for supplying waste in a substantially horizontal direction is provided at the waste supply port provided in the cylindrical furnace wall, waste is supplied from the center of the furnace ceiling, It is not necessary to provide a chute that allows the waste to fall smoothly and be supplied to the center of the hearth, so that the overall height (height) of the facility can be lowered.

FIG. 1 is a longitudinal sectional view showing the overall configuration of a cylindrical fluidized bed furnace of the present invention. 2 is a sectional view taken along line II-II in FIG. FIG. 3A is a plan view showing a cylindrical furnace wall and a floor plate of the furnace body, and FIG. 3B is a longitudinal sectional view showing a cylindrical furnace wall and the floor plate of the furnace body. FIG. 4 is an enlarged view of the main part of FIG.

  Embodiments of a cylindrical fluidized bed furnace according to the present invention will be described below with reference to FIGS. In the drawings, the same or similar members are denoted by the same or similar reference numerals, and redundant description is omitted.

  FIG. 1 is a longitudinal sectional view showing the overall configuration of a cylindrical fluidized bed furnace of the present invention. 2 is a cross-sectional view taken along line II-II in FIG. As shown in FIGS. 1 and 2, a cylindrical fluidized bed furnace 1 includes a furnace body 10 that processes waste W, a fluidized bed 20 that thermally reacts the introduced waste W, and a floor plate 30 that supports the fluidized bed 20. And. The fluidized bed 20 is a bed formed by accumulating a fluid medium that is typically sand such as silica sand. The furnace body 10 is formed of a cylindrical furnace body in which the horizontal cross section of the hearth is formed in a circular shape. An incombustible discharge port 11 is provided at a position eccentric from the center of the cylindrical furnace body at the bottom of the furnace body 10. As shown in FIG. 2, the incombustible discharge port 11 has a circular horizontal cross section, and the center 11o of the incombustible discharge port 11 is eccentric from the center (axial center) 10o of the cylindrical furnace body 10 by a distance L. Yes. The eccentric distance L is set to L (mm) = 0.086 d (mm) to (d−1000) / 2 (mm), where d is the inner diameter of the cylindrical furnace body 10. (However, d (mm)> 1500 mm)

  A waste supply device 40 including a screw feeder is installed on the furnace wall of the furnace body 10 at a position farthest from the incombustible discharge port 11. A waste supply port 41 is formed at the tip of the waste supply device 40. In other words, the waste W is supplied to the fluidized bed 20 from the waste supply port 41 formed on the furnace wall far from the incombustible discharge port 11. As described above, since the waste supply port 40 provided with the screw feeder that supplies the waste W in the substantially horizontal direction is provided at the waste supply port 41 provided in the cylindrical furnace wall, the waste W is supplied from the center of the furnace ceiling. There is no need to supply or provide a chute that allows the waste W to smoothly fall and be supplied to the center of the hearth, and the overall height (height) of the facility can be reduced.

  Further, an exhaust port 12 for discharging a gas generated when the waste W is subjected to a thermal reaction is formed in the upper portion of the furnace body 10. A space above the fluidized bed 20 in the furnace body 10 is a free board 13. When the furnace body 10 is an incinerator, the combustion gas is discharged from the exhaust port 12 by supplying secondary air to the free board 13 and burning the combustible gas. When the furnace body 10 is a gasification furnace, combustible gas is discharged from the exhaust port 12.

  FIG. 3A is a plan view showing the cylindrical furnace wall and the floor plate 30 of the furnace body 10, and FIG. 3B is a longitudinal sectional view showing the cylindrical furnace wall and the floor board 30 of the furnace body 10. . As shown in FIG. 3 (a), the floor plate 30 is formed in a substantially inverted conical shape (conical shape) with the incombustible discharge port 11 as a center, and the floor plate 30 is supplied with fluidized air as a fluidizing gas in a furnace. A large number of air diffuser nozzles 31 and 32 for jetting in are arranged. These aeration nozzles 31 and 32 constitute gas supply ports for supplying fluidized air to flow the fluid medium. The diffuser nozzles 31 and 32 are arranged on a plurality of concentric circles (C1, C2, C3, C4, C5) centering on the incombustible discharge port 11. In FIG. 3A, only a part of the diffuser nozzles 31 and 32 arranged on the concentric circles (C1 to C5) is illustrated. Since C3, C4, and C5 are arcs instead of circles, the following explanation will be made as arcs C3, C4, and C5.

  As shown in FIG. 3B, a bottom plate 33 is provided below the floor plate 30 with a space from the floor plate 30, and the space between the floor plate 30 and the bottom plate 33 is from the floor plate 30 to the bottom plate 33. It is divided into two spaces by an extending partition plate 34. In FIG. 3A, as shown by the dotted line, the partition plate 34 divides two concentric circles C1 and C2 and three arcs C3, C4, and C5 out of the five concentric circles and arcs C1 to C5. Has been placed. As described above, the space between the floor plate 30 and the bottom plate 33 is divided by the partition plate 34, whereby two air boxes 35 and 36 are formed below the floor plate 30. Air pipes 51 and 52 for guiding fluidized air from outside the furnace to the air boxes 35 and 36 are connected to the two air boxes 35 and 36, respectively. The air pipes 51 and 52 are respectively provided with control valves V1 and V2 for adjusting the flow rate of air flowing inside. The two air pipes 51 and 52 join together at the most upstream portion to form one air pipe 53, and an air blower 54 that pumps fluidized air is disposed in the air pipe 53. In addition, you may provide a blower in the air pipes 51 and 52, respectively.

  FIG. 4 is an enlarged view of the main part of FIG. In FIG. 4, the aeration nozzles 31 and 32 are not shown. In the fluidized air supply system configured as shown in FIG. 3B, the flow rate of the air flowing through the air pipe 51 is adjusted by adjusting the opening of the control valve V1, so that the two concentric circles C1 and C2 are placed. From the arranged aeration nozzle 31, fluidized air is ejected so as to give a substantially large fluidization speed. As a result, as shown in FIG. 4, a strong fluidization zone SF in which the fluid medium actively flows is formed above the two concentric circles C <b> 1 and C <b> 2 of the floor plate 30. Further, by adjusting the opening of the control valve V2 shown in FIG. 3B to adjust the flow rate of air flowing through the air pipe 52, the air diffuser nozzles 32 arranged on the three arcs C3, C4, C5 are used. Jets fluidized air to provide a substantially small fluidization rate. As a result, as shown in FIG. 4, a weak fluidization zone WF is formed above the three arcs C3, C4, C5 of the floor plate 30 where the fluid medium flows at a relatively slow speed.

  As shown in FIG. 4, of the two concentric circles C1 and C2, a strong fluidization zone formed above the substantially semicircular portions C1-1 and C2-1 adjacent to the arcs C3, C4 and C5. As a result of the SF and the weak fluidization zone WF formed above the three arcs C3, C4, C5, the fluidized medium moves downward from above at a relatively slow speed in the weak fluidization zone WF. Is formed, and a fluidized bed 22 is formed in which the fluidized medium moves upward from below in the strong fluidization zone SF. Therefore, in the entire region where the weak fluidization zone WF and the strong fluidization zone WF are adjacent to each other, the fluidized medium is from the weak fluidization zone WF to the strong fluidization zone SF (moving bed 21 to fluidized bed 22) in the lower part. In the upper part, by moving from the strong fluidization zone SF to the weak fluidization zone WF (from the fluidized bed 22 to the moving bed 21), the weak fluidizing zone WF and the strong fluidized zone SF (moving bed 21 and fluidized bed 22) A circulating flow in which the fluid medium circulates between the two is formed.

  On the other hand, of the two concentric circles C1 and C2, the strong fluidization areas SF formed above the substantially semicircular portions C1-2 and C2-2 on the opposite side of the arcs C3, C4, and C5 are adjacent to each other. Since there is no weak fluidization zone, this zone becomes a so-called bubbling fluidized bed in which the fluid medium repeats vertical movement. That is, as shown in FIG. 4, the fluidized bed 20 includes a circulating fluidized bed formed by the moving bed 21 and the fluidized bed 22 adjacent to each other, and a strong fluidized zone. The bubbling fluidized bed formed will coexist. In FIG. 4, the circulating fluidized bed is formed in a region represented by a substantially fan-shaped closed curve CL. The bubbling fluidized bed is formed in a region opposite to the region represented by the closed curve CL with the incombustible discharge port 11 in between. As shown in FIG. 2, the center 11 o of the incombustible discharge port 11 is provided eccentric from the center (axial center) 10 o of the cylindrical furnace body 10.

  Moreover, the waste supply apparatus 40 which consists of a screw feeder is provided in the furnace wall of the position which is on the line which extended the line which connects the center 11o and the center 10o, and was most separated from the incombustible material discharge port 11. FIG. Therefore, a large-sized circulating fluidized bed (generally fan-shaped) is formed between the waste supply unit in the hearth just below the waste supply port 41 at the tip of the waste supply device 40 and the incombustible discharge port 11. Of the closed curve CL). This circulating fluidized bed has a fluidized bed with a substantially fan-shaped horizontal section. In this fluidized bed having a generally fan-shaped surface, the fluid medium is circulated between the moving bed in the periphery of the furnace and the fluidized bed in the center of the furnace. When the flow is formed, the fluidized medium does not diffuse in the circumferential direction of the circle, so that the fluidized medium circulates like a fluidized bed having a rectangular horizontal section. Since the moving bed 21 in which the fluid medium moves from the upper side to the lower side at a relatively slow speed is formed immediately below the waste supply port 41, the waste supplied from the waste supply device 40 to the fluidized bed 20 is disposed. The object W can be swallowed immediately by the settling flow of the moving bed 21.

  In FIG. 4, it is also possible to make a difference in the fluidization speed in the strong fluidization region SF by providing a difference in the fluidization air amount of the air diffusion nozzle 31 between C1-1 and C2-1. By doing in this way, the flow of the strong fluidization area SF can be finely adjusted. Further, in the weak fluidization zone WF formed above the three arcs C3, C4, and C5, the amount of fluidized air in the arc is relatively decreased in the order of C3, C4, and C5, and the difference between two or three stages is achieved. It is also possible to make the fluidization speed with a mark. By doing in this way, the sedimentation of the weak fluidization zone WF can be finely adjusted. By finely changing the fluidization speed in the strong fluidization zone SF and the weak fluidization zone WF, the thermal reaction due to the rise and sedimentation of the fluidized medium can be advanced more efficiently. By making a difference in fluidization speed between the above-described C1-1 and C2-1, it is inevitably possible to make a difference in fluidization speed even in the bubbling fluidized bed of the approximately semicircular portions C1-2 and C2-2. it can.

  In the example shown in FIGS. 3A and 3B, the space below the floor plate 30 is divided into two air boxes 35 and 36 by the partition plate 34. However, the partition plate 34 is omitted and one air is provided. It is good also as a box. In that case, the number of the diffuser nozzles 31 per unit area in the region where the two concentric circles C1 and C2 are present is larger than the number of diffuser nozzles 32 per unit area in the region where the three arcs C3, C4 and C5 are present. By increasing the amount, the amount of fluidized air in the region where the two concentric circles C1 and C2 are present is made larger than the amount of fluidized air in the region where the three arcs C3, C4 and C5 are present so as to differentiate the fluidization speed. That's fine. Alternatively, the airflow resistance of the air diffuser nozzle 31 per unit area in the region having the two concentric circles C1 and C2 is smaller than the airflow resistance of the air diffuser nozzle 32 per unit area in the region having the three arcs C3, C4, and C5. By adjusting the hole diameters of the diffuser nozzle 31 and the diffuser nozzle 32 as described above, the fluidized air amount in the region where the two concentric circles C1 and C2 are present is changed to the fluidized air amount in the region where the three arcs C3, C4 and C5 are present. It is sufficient to increase the difference in fluidization speed.

However, if the number of diffuser nozzles and the diameter of the blowout hole are determined, the distribution of the fluidized air amount also changes when the fluidized air amount is changed. For this reason, in order to make it possible to adjust the fluidizing air amount without changing the distribution of the fluidizing air amount, the air box under the floor board is divided (concentrically), and each air box is divided. It is preferable that the amount of fluidized air can be adjusted.
In the example shown in FIG. 3A and FIG. 3B, the space below the floor plate 30 is divided into two air boxes 35 and 36 by the partition plate 34, but fluidized air in two concentric circles C1 and C2. When providing a difference in quantity, the air box 35 may be further divided by a partition plate (not shown) for each region where each circle exists. Similarly, in the three arcs C3, C4, and C5, the air box 36 is further divided into two parts (for example, divided into C3, C4, and C5) or divided into three parts for each arc, so that each of C3, C4, and C5 is obtained. You may make it give the difference of 2 steps | paragraphs or 3 steps | paragraphs to the fluidization air quantity of an area | region.

  Next, the operation of the cylindrical fluidized bed furnace 1 configured as shown in FIGS. 1 to 4 will be described. The waste W processed in the fluidized bed furnace 1 is typically assumed to be non-uniform in quality and quantity, such as municipal waste, sludge, and wood scrap, and which tends to become unstable. In the present embodiment, it is assumed that it is municipal waste. Waste W generally consists of moisture, combustible components, and ash (including non-combustible materials). The water evaporates due to thermal reaction, and some of the combustible components volatilize as combustible gas (pyrolysis gas). Minute residue Wr. The waste water W evaporates and the combustible gas is volatilized, that is, the unburned material (char) Wc and the non-combustible material Wn are the pyrolysis residue Wr. The unburned matter (char) Wc in the pyrolysis residue Wr is separated from the incombustible material Wn in the fluidized bed 22 and then partially burned in the fluidized bed 22 to burn combustion gas and fine unburned matter (char). ) Wc is preferably sent to the freeboard 13 together with the fluidized air.

  The waste W is supplied to the moving bed 21 by a waste supply device 40 including a screw feeder. At this time, the flow rate of the fluidized air supplied to the fluidized bed 22 and the moving bed 21 is adjusted by adjusting the opening degree of the control valves V1, V2. Typically, the fluidized air supplied to the fluidized bed 22 can be moved by the control valve V1 until it reaches the moving bed 21 while conveying the fluidized medium of the fluidized bed 22 upward. Thus, the flow rate is adjusted so that air (oxygen) capable of burning the unburned material (char) Wc can be supplied to the fluidized bed 22. “Burning the unburned material (char) Wc on a predetermined basis” typically means that the unburned material exceeding a predetermined concentration does not flow out of the fluidized bed furnace 1 together with the incombustible material Wn. In addition to reducing the unburned matter concentration in the fluidized bed 20, the fluidized medium retains an amount of heat that can appropriately perform the thermal decomposition of the waste W in the moving bed 21 by the fluidized medium transferred from the fluidized bed 22 to the moving bed 21. In the fluidized bed 22, unburned matter (char) Wc is burned.

  Here, the “predetermined concentration” of the unburned material “unburned material exceeding the predetermined concentration does not flow out of the fluidized bed furnace 1 together with the unburned material Wn” is typically unexposed to the fluid medium or the unburned material Wn. Since the dioxins are likely to be included in the unburned material (char) Wc when the burned material (char) Wc is attached and entrained, the unburned material Wn should not have a high concentration of dioxins. The concentration is controlled to be 0 to 0.1% by weight.

  In order to prevent unburned substances exceeding a predetermined concentration from being discharged out of the fluidized bed furnace 1 together with the incombustibles Wn, the thermal decomposition of the waste W in the moving bed 21 is not performed when moving to the fluidized bed 22. It is possible to generate a thermal decomposition residue Wr that is brittle to the extent that the combustion material (char) Wc is appropriately separated from the non-combustible material Wn (appropriate thermal decomposition of the waste W). On the other hand, the fluidized air supplied to the moving bed 21 is adjusted to a flow rate that allows the flowing medium of the moving bed 21 to circulate and flow with the fluidized bed 22. The mass flow rate of the fluidized air supplied to the moving bed 21 is adjusted so that the mass flow rate of the fluidized air supplied to the moving bed 22 is smaller than the mass flow rate of the fluidized air supplied to the fluidized bed 22. The flow rate is set to 0.5 to 1.5 Gmf, and the mass flow rate of fluidized air supplied to the fluidized bed 22 is set to about 1.5 to 5 Gmf. The mass flow rate at which the fluid medium starts fluidizing is 1 Gmf.

The waste W supplied to the moving bed 21 is swallowed by the moving bed 21 and moves downward together with the fluidized medium. At this time, the waste W is dried and pyrolyzed by the heat of the fluidized medium, the water in the waste W evaporates, combustible gas is generated from the combustible matter in the waste W, and the brittle pyrolysis residue Wr It becomes. The thermal decomposition residue Wr typically includes an incombustible material Wn and an unburned material (char) Wc that has become brittle by thermal decomposition. When the pyrolysis residue Wr produced in the moving bed 21 reaches the floor plate 30 together with the fluidized medium, it goes to the fluidized bed 22 along the inclined floor plate 30. The pyrolysis residue Wr that has reached the fluidized bed 22 is separated from the incombustible material (char) Wc by the fluidized air, and a part of the incombustible material Wn remaining after the unburned material (char) Wc is separated. To the incombustible discharge port 11 together with the fluid medium. At this time, since the incombustible discharge port 11 is eccentric by a distance L from the center (axial center) 10o of the cylindrical furnace body 10, the movement for separating the unburned material (char) Wc from the incombustible material Wn. The distance can be secured, and the non-combustible material Wn in the pyrolysis residue Wr surely moves a certain distance of the fluidized bed 22 to appropriately separate the unburned material (char) Wc and the non-combustible material Wn. Can be done. The non-combustible material Wn flows into the non-combustible material discharge port 11 together with a part of the fluid medium and is discharged out of the fluidized bed furnace 1, and non-oxidized and unburned material (char) adheres to the non-combustible material separator (not shown). It is collected without any. The fluid medium after the incombustible material Wn is collected by the incombustible material separation device (not shown) is returned to the furnace body 10 through the fluid medium circulation device (not shown).
As shown in FIG. 3B, the radius of the incombustible discharge port 11 is R ₀ , the radius from the center 11o of the incombustible discharge port 11 to the furnace wall of the furnace body 10 is R ₁ , and the center of the incombustible discharge port 11 the radius to the partition plate 34 when the _{R 2} from 11o, the moving distance of the fluidized bed is _(R 2 -R _0). Since the center 11o of the incombustible discharge port 11 is allowed only eccentric center (axial center) Distance from 10o L of the cylindrical furnace body 10, R ₂ is increased, the moving distance of the fluidized bed is increased. Incidentally, R ₂ = R ₁ / √2.

  On the other hand, the unburned material (char) Wc peeled off from the non-combustible material Wn moves upward together with the fluid medium that flows as fluidized air is supplied. At this time, the unburned matter (char) Wc is combusted by the supplied fluidized air, generates a combustion gas while heating the fluidized medium, and is transported to the gas. ) And ash particles. In the fluidized bed 22, the temperature gradually increases as the unburned substance (char) Wc is burned, so that the temperature increases proportionally from the lower part to the upper part. On the other hand, the fluid medium reaching the upper part of the fluidized bed 22 flows into the moving bed 21. The fluidized medium is raised in the fluidized bed 22 to a temperature at which the waste W can be appropriately thermally decomposed when it flows into the moving bed 21. The fluid medium flowing into the moving bed 21 receives the waste W supplied again and repeats the thermal reaction in the moving bed 21 and the fluidized bed 22 described above.

  In the fluidized bed furnace 1 that operates as described above, the unburnt material (char) Wc is not completely separated from the incombustible material Wn and is prevented from flowing out to the incombustible material discharge port 11 together with the incombustible material Wn. The temperature of the fluidized bed 22 is adjusted by adjusting the flow rate. Since the increase / decrease in the fluidized air is related to the increase / decrease in the oxygen used to burn the unburned matter (char) Wc, the temperature of the fluidized bed 22 increases and increases the flow rate of the fluidized air. And descend.

  On the other hand, the waste W such as municipal waste has a situation in which combustion is difficult to stabilize because of the variation in the amount of retained heat. If the quality and quantity of waste W introduced into the fluidized bed furnace 1 per unit time is not stable, the amount of combustible gas and combustion gas varies, so the pressure in the fluidized bed furnace 1 varies, Stable operation of the fluidized bed furnace 1 becomes difficult. In order to suppress fluctuations in the amount of generated combustible gas, it is preferable to slowly dry and thermally decompose the waste W in the moving bed 21. When drying and thermal decomposition of the waste W in the moving bed 21 are performed slowly, fluctuations in the amount of thermal decomposition residue Wr entering the fluidized bed 22 are also suppressed, so fluctuations in the amount of combustion gas generated are also suppressed. It becomes. In order to moderate the drying and thermal decomposition of the waste W in the moving layer 21, the temperature of the moving layer 21 may be lowered as much as possible within a range where the thermal decomposition of the waste W can be appropriately performed.

  In the fluidized bed furnace 1 of the present embodiment, the non-combustible material discharge port 11 is provided in addition to the circulating fluidized bed (indicated by the closed curve CL) in which the horizontal section having the moving bed 21 and the fluidized bed 22 is substantially fan-shaped. By forming a bubbling fluidized bed on the opposite side of the region indicated by the closed curve CL, the amount of fluidized air around the incombustible material discharge port 11 is increased, and the fixed layer is the minimum region directly above the incombustible material discharge port. As described above, waste and pyrolysis residue (char) are prevented from being discharged from the incombustible discharge port 11.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Cylindrical fluidized bed furnace 10 Furnace main body 10o Center 11 Incombustible material discharge port 11o Center 13 Free board 20 Fluidized bed 21 Moving bed 22 Fluidized bed 30 Floor plate 33 Bottom plate 34 Partition plate 35, 36 Air box 31, 32 Air diffuser nozzle 40 Disposal Material supply device 41 Waste supply port 51, 52, 53 Air pipe 54 Air blower C1, C2, C3, C4, C5 Concentric circle d Inner diameter L Eccentric distance SF Strong fluidization zone WF Weak fluidization zone V1, V2 Control valve

Claims (6)

In a fluidized bed furnace that treats waste,
A cylindrical furnace body with a circular horizontal cross section;
A floor plate disposed at the bottom of the furnace body and provided with a gas supply port for supplying a fluidizing gas to flow a fluid medium;
An incombustible discharge port provided at the bottom of the cylindrical furnace body and arranged eccentrically from the axis of the cylindrical furnace body;
A waste supply port provided on the furnace wall on the opposite side of the incombustible discharge port across the axis of the cylindrical furnace body,
The waste supply port side and the incombustible discharge port are connected to the supply amount of fluidized gas ejected from the gas supply port provided on the floor plate between the furnace wall on the side where the waste supply port is located and the incombustible discharge port. A fluidization speed on the non-combustible discharge port side is made larger than the fluidization speed on the waste supply port side by forming a difference between the side and the moving medium in which the fluid medium settles on the waste supply port side, Forming a fluidized bed in which the fluidized medium rises on the incombustible discharge port side ;
The fluidization speed between the furnace wall on the side opposite to the furnace wall on the side where the waste supply port is located across the axial center of the cylindrical furnace main body and the incombustible material discharge port is the incombustible material discharge port side. A cylindrical fluidized bed furnace in which a bubbling fluidized bed in which the fluidized medium repeatedly moves up and down is formed around the incombustible discharge port, at the same fluidization speed as the above.   The gas supply port provided on the floor plate between the furnace wall on the side where the waste supply port is located and the incombustible discharge port is divided into a gas supply port on the waste supply port side and a gas supply port on the incombustible discharge port side. The cylindrical fluidized bed furnace according to claim 1, wherein the cylindrical fluidized bed furnace is divided into two or more.   The gas supply port provided in the floor plate between the furnace wall on the side where the waste supply port is located and the incombustible discharge port is partitioned by dividing the air box provided under the floor plate with a partition. The cylindrical fluidized bed furnace according to claim 2.   A circulating flow in which a fluid medium circulates between the moving bed and the fluidized bed is formed in a furnace region between the furnace wall on the side where the waste supply port is located and the incombustible discharge port. The cylindrical fluidized bed furnace according to any one of claims 1 to 3, wherein the cylindrical fluidized bed furnace is provided. The said gas supply port provided in the said floor board is arrange | positioned on the concentric circle centering on the said incombustible discharge port, and the concentric circular arc, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Cylindrical fluidized bed furnace. The cylindrical fluidized bed furnace according to any one of claims 1 to 5 , wherein a waste supply device including a screw feeder is installed at a position of the waste supply port.

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