JPH0158406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal reactor such as an incinerator or a pyrolysis furnace using a fluidized bed.

[Prior Art] As this type of thermal reactor, for example, in incinerators for municipal waste, fluidized bed furnaces have recently been used, which have better incineration efficiency than stoker furnaces and produce less incineration residue.

At that time, if garbage was thrown in at a certain size or larger, it would hinder the fluidization of the fluidized medium, so in order to prevent this, it was pre-treated using a crusher before being thrown into the incinerator. Was. Therefore, crushing equipment including a crusher is required, which causes problems in terms of space and cost. In addition, using a shredder can cause problems such as wear and tear on the blades due to non-flammable foreign objects (irons, hammer heads, cannonballs, concrete blocks, etc.) that get mixed into the garbage, and even though they are flammable, Bulky garbage (for example, futons, blankets, fishing nets, etc.) is difficult to crush, which causes many problems, such as increased crushing power or the crusher stopping because it cannot be crushed. Furthermore, in the case of such a problem, the crusher must be disassembled or a person must enter the crusher to manually remove the foreign matter, which increases the effort and cost of maintenance. The process had to be stopped, which significantly hindered work efficiency.

On the other hand, in terms of incineration capacity, the maximum capacity of the furnaces in operation at the time was approximately 75 tons/24 hours.
Even in the design, the maximum is about 150t/24h,
It was difficult to realize a larger capacity than this.

In order to solve these problems, the present inventors developed a fluidized bed furnace that does not require pre-crushing treatment and can be made larger, by rotating the fluidized medium in a vertical plane in the furnace space. In order to solve the conventional drawbacks by circulating the fluidized medium to form a fluidized bed and a moving bed, a fluidized bed thermal reactor as disclosed in Japanese Patent Application Laid-open No. 124608/1983 was invented.

[Problem that the invention seeks to solve]

However, even with the fluidized bed furnace disclosed in Japanese Patent Application Laid-Open No. 57-124608, it was thought that about 300 t/d was the practical limit when it came to increasing the size. For example, in a municipal waste incinerator, the hearth load of a fluidized bed furnace is
Generally, the value is about 450Kg/m ² h. On the other hand, in the fluidized bed thermal reactor invented by the present inventors (Japanese Unexamined Patent Publication No. 124608/1982), a swirling flow is generated by the combination of a moving bed and a fluidized bed as shown in Fig. 11, and large waste In order to move heavy noncombustible materials laterally without settling on the hearth, and to perform effective combustion and discharge of noncombustible materials, there is a limit to the width of the furnace. There is.

Here, for example, when calculating the hearth area for a 1000t/d furnace based on 450Kg/m ² h, the hearth area A = 1000t/d/24h x 1/0.45t/m ² h = 92.6m ² A = Dividing 92.6m ² by furnace width L = 4m gives approximately 23.2m. At this time, the hearth module becomes an extremely elongated hearth as shown in FIG. 12, resulting in an unrealistic furnace shape.

The present invention aims to eliminate these drawbacks and provide a fluidized bed thermal reactor that can be made extremely large.

[Means for solving problems]

The present invention includes a fluidizing dispersion plate, and the dispersion plate has both side edges lower than the center, and is formed in a chevron-shaped cross section that is substantially symmetrical with respect to the center line, so that the fluidizing gas mass velocity at the both side edges is reduced. A plurality of sets of fluidized bed thermal reaction sections, each of which is larger than the fluidized gas mass velocity in the central section, are installed in parallel at the bottom of the same furnace, and a common incombustible material discharge port is provided between each of the dispersion plates. A non-combustible material discharge port is provided at each side edge, and reflecting walls are provided directly above the both side edges of each of the dispersion plates for reflecting and diverting the upward flow of fluidizing gas toward the center of each fluidized bed thermal reaction section, A raw material inlet is provided in the ceiling of the furnace so as to correspond to the central part of each of the distribution plates, and the furnace space surrounded by the furnace wall, the distribution plates, and the ceiling is provided with a reflecting wall on the inside of the furnace. This is a fluidized bed reactor characterized by being formed as an integral space.

〔Example〕

The present invention will be described with reference to the drawings, using a practical example in which a dispersion plate is used as a dispersion mechanism for fluidizing air in a municipal waste incinerator.

FIG. 1 shows an example of municipal waste incineration equipment using a fluidized bed incinerator 6, in which waste stored in a waste pit 1 is transferred to a hopper 4 by a bucket 3 of a crane 2.
and is supplied to an incinerator 6 by a dust supply device 5, which is a supply device. In the incinerator 6, the fluidizing gas supplied by the blower 7 is ejected upward from the dispersion plate 8 into the furnace, hits the inclined wall 9 and becomes a swirling flow 10 in a vertical plane, dislodging the fluidized medium such as sand. A swirling fluidized bed is formed by flowing along this line. Furthermore, as will be described later, a descending moving bed is formed in the center of the furnace, and the swirling fluidized bed and descending moving bed allow the waste to be burnt well in a short period of time.
Even if crushing is not performed in advance, high combustion efficiency can be obtained without inhibiting fluidization.

11 is a combustion exhaust gas duct, 12 is a non-combustible material discharge device, 13 is a vibrating sieve, 14 is a conveyor for discharging lump non-combustible materials, and 15 is an elevator for collecting a fluid medium such as sand.

As shown in FIGS. 2 and 3, for example, the dust supply device 5 has a structure in which a hopper 4 is connected to a conveyor case 20 via a waste inlet 16, and waste outlets 17 are provided at both lower ends. It is being Inside the conveyor case 20, the conveyor case 20 rotates in mutually opposite directions so that the raw materials inputted near the center are distributed left and right and transported by applying twists in opposite directions from the center to the left and right. During normal operation, at least two screws 21 and 22 are provided, which rotate in the normal direction so that the upper sides approach each other, are held parallel to each other, and are twisted in opposite directions. The pitch of the blades 23, 24 of the screws 21, 22 is larger near the outlet 17 than the pitch near the inlet 16.

In addition, the outer diameter is gradually increased at the continuous point of the screw twisted in the opposite direction approximately in the center so as not to attract dust.

One screw 22 is connected to the conveyor case 20
It is supported by bearings 25 and 26 at a fixed position relative to the motor 27, and is directly rotated by a motor 27. During normal operation, the screw 22 rotates in a normal counterclockwise direction when viewed from the motor 27 side, and the screw 21 rotates in a normal clockwise direction.

As shown in FIGS. 3 and 4, the screw 21 is connected to the guide rail 3 by cylinders 28 and 29.
It is supported by moving bearings 31 and 32 that move along 0. Since the cylinders 28 and 29 are configured to be displaced by equal distances as will be described later, the screw 21 moves parallel to the screw 22, and the center distance adjustment changes from l ₁ to l ₂
It is now being carried out until now.

The shaft ends of the screws 21 and 22 on the motor 27 side are connected to links 33 and 3 as shown in FIGS.
4 and gears 35, 36, 37, and 38, the screw 21 continues to be driven and rotated in the opposite direction to the screw 22 even while the distance between the shafts is changing from l ₁ to l ₂ . ing.

If dirt gets caught between the screws 21 and 22, the dirt will cause the screws 21 and 22 to
is subjected to an expanding force that increases the distance between their axes, so if this expanding force is large, it will cause damage to the screws 21, 22 and other parts.
These problems must be prevented.

In order to meet these requirements, the distance between the axes is adjusted as shown in FIGS. 7a and 7b. That is, assuming that the distance between the shafts is the minimum distance between the shafts l ₁ and the maximum distance between the shafts during steady state l ₂ , the dust 39 caught between the screws 21 and 22
The expansion force generated by this is detected as the oil pressure of the cylinders 28 and 29. For example, as will be described later, an allowable enlarging force is set as an allowable value of the enlarging force in a hydraulic circuit.

During normal operation, crushing and bag tearing are performed at the minimum distance _l1 between the centers as shown in FIG. 7a. big garbage 39
Or, if a lump of incombustible material enters and the expanding force exceeds the allowable expanding force, the distance between the axes will open until the expanding force falls to the allowable expanding force in the range of l ₁ to _{l 2} . Even when the bag is being opened, the screws 21 and 22 continue to rotate in the normal direction, and destruction, bag tearing, and transfer are continuously performed.

FIG. 8 shows an example of a hydraulic circuit for adjusting the distance between the shafts as described above.

Next, the incinerator 6 will be explained.

As shown in FIG. 9, two sets of fluidizing air distribution plates 8 are installed side by side on the left and right at the bottom of the incinerator 6, and the left and right distribution plates 8 have both side edges lower than the center and It is formed in a chevron-shaped cross section (roof-like) that is almost symmetrical with respect to the line. The inclination may be different between the center portion and both side edge portions. Non-combustible material discharge ports 4 on both side edges
2 are connected, and the incombustible material discharge port 42 in the center of the furnace is shared by one location.

The fluidized air sent from the blower 7 is sent to the air chamber 4.
The mass velocity (Kg/m ² /sec) of the fluidized air is ejected upward from each dispersion plate 8 via air chambers 43 and 45 on both side edges. is large enough to form a fluidized bed, but the mass velocity of the fluidized air jetting out of the central air chamber 44 is chosen to be smaller than the former.

For example, the mass velocity of the fluidized air ejected from the air chambers 43, 45 is 4 to 20 Gmf, preferably 5 to 20 Gmf.
10 Gmf, whereas the mass velocity of the fluidized air ejected from the air chamber 44 is selected to be 0.5 to 3 Gmf, preferably 1 to 2.5 Gmf. Here, 1 Gmf is the fluidization starting mass velocity.

The number of air chambers is chosen arbitrarily for each distribution plate 8, and even in the case of a large number, the mass velocity of the fluidized air is
Make the one closest to the center smaller, and the one closer to the edges on both sides larger.

Also, the air chambers 43, 4 on the side edge of the distribution plate 8 on the furnace wall side
3 and directly above the air chambers 45, 45 on the furnace center side,
A sloped wall 9 is provided as a reflective wall that blocks the upward flow path of the fluidized air and reflects and diverts the fluidized air toward the center of the furnace. Sloped surface 46 with opposite slope
are provided to prevent the flow medium from accumulating.

In addition, the inclined wall 9 on the furnace center side is bridged in the furnace as a beam with a hollow cross section as shown in the illustrated example so that it can be used as a reflecting wall on the left and right dispersion plates 8 at the same time, and the upper side thereof also has inclined surfaces on the left and right. 46 is formed to prevent the accumulation of the fluidizing medium.The inclined wall 9 may be a wall body made of a metal pipe, and water may be passed through the pipe to generate steam or to produce hot water.

The inclination of the dispersion plate 8 is preferably about 5 to 15 degrees, and the inclination of the inclined wall 9 is preferably about 10 to 60 degrees with respect to the horizontal.

Furthermore, two or more raw material input ports 48 connected to the outlet 17 of the dust supply device 5 are provided in the furnace ceiling 47 so as to correspond to the left and right air chambers 44 in the center.

In this way, the furnace wall, the distribution plate 8 and the ceiling part 4
The furnace space surrounded by 7 and 7 is formed as an integral space with a reflecting wall bridged in the center.

Next, to explain the function of the incinerator 6, the blower 7 sends fluidized air into the air chamber 43,
The air is ejected from the air chamber 45 at a high mass velocity, and from the air chamber 44 at a small mass velocity.

In a normal fluidized bed, the fluidized medium violently moves up and down like boiling water to form a fluidized state, but the fluidized medium above the air chamber 44 does not move violently up and down, but has a weak flow. form a moving layer in the state. The width of this moving layer is narrow at the top, but it widens slightly at the bottom due to the effect of the slope of the dispersion plate 8.
45, it receives a jet of air with a large mass velocity and is blown up. Since some of the fluid medium at the skirt is removed, the layer directly above the air chamber 44 will fall under its own weight. A fluidized medium from a fluidized bed with a swirling flow 10 is replenished and deposited above this layer as will be described later. By repeating this process, the fluidized medium above the air chamber 44 almost comes together in a certain region, forming a downwardly moving layer that gradually descends.

The fluidized medium that has moved onto the air chambers 43 and 45 is blown upward, but it hits the inclined wall 9 and is reflected and turned upwards toward the center of the thermal reaction area surrounded by the inclined wall 9, causing a rapid increase in the cross section inside the furnace. As a result, the air loses its rising speed, falls to the top of the downwardly moving layer, gradually descends, reaches the bottom, and is blown up again to circulate. A portion of the fluidized medium circulates in the fluidized bed as a swirling flow 10.

The waste input into the incinerator 6 in this state from the raw material input port 48 descends to the top of the downwardly moving layer on each distribution plate 8. Near the top, the flow of the fluid medium flows in a concentrated direction from the outside toward the center, so that the debris is caught up in this flow and sucked into the top of the downwardly moving bed. Therefore, even light materials such as paper can be reliably taken into the descending moving bed, so that the paper burns on the sand and burns without contributing significantly to the heating of the fluidized medium, as in conventional fluidized beds. This can be prevented and the fluidized medium can be reliably heated by combustion in the descending moving bed and the swirling flow 10.

In the descending moving bed, thermal decomposition occurs partially and combustible gas is generated.The generated combustible gas spreads horizontally and enters the fluidized bed where it is combusted, so the heat is effective for heating the fluidized medium. useful for.

When heavy and large objects such as bottles and irons are dropped onto the surface of the downwardly moving layer, these objects do not fall instantly to the top of the air chamber 44, but are supported by the downwardly moving layer. As the fluid medium flows, it gradually spreads left and right and descends.

Therefore, even if the combustible material is quite large, it will dry, gasify, and burn as it gradually descends and diffuses in the descending moving layer, and by the time it reaches the bottom, most of it will be burned and fragmented. Therefore, the formation of a fluidized bed is not inhibited.

Therefore, even if the garbage is not crushed in advance using a crusher, it is sufficient to break the bags using the dust supply device 5.
The crusher and crushing process can be omitted, resulting in a compact device.

In addition, since the waste thrown into the descending moving bed is quickly diffused into the fluidized medium, the combustion efficiency is increased.

The non-combustible materials supplied through the dust supply device 5 are
First, it moves downward and laterally through each descending layer, but at this time, combustible materials that adhere to non-combustible materials or are assembled together (for example, the covering of electric wires) are burned.
Non-combustible materials that have reached the hem are transported by horizontal movement of the fluid medium and distributed by the dispersion plate 8.
The incombustible materials reach each incombustible material discharge port 42 due to the slope of the incombustible material and are smoothly discharged.

Also, looking at the hearth module,
If we calculate the hearth module for a 1000t/d furnace, the hearth area = ^92.6m2 , whereas in the conventional example it is approximately 4m (hearth width) x 23.2m (hearth length) as mentioned above. (Fig. 12), as shown in Fig. 10, the furnace has a well-balanced shape of approximately 8 m (hearth width) x 11.6 m (heart length), making it easy to construct an ultra-large furnace of approximately 1000 t/d. It can be made possible.

In the above example, two sets of thermal reaction units are arranged in parallel, but it is also possible to arrange three or more sets in parallel.

〔Effect of the invention〕

As described above, according to the present invention, municipal waste,
In an incinerator or pyrolysis furnace that efficiently burns all kinds of combustible materials such as sludge and coal, it not only has the various effects shown in the conventional Japanese Patent Application Laid-open No. 57-124608, but also in a furnace with a large furnace width. It is also possible to keep the moving distance of non-combustibles short and prevent them from stagnation.
This has the extremely beneficial effect of easily making it possible to increase the size of the furnace, which was previously considered impossible.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a cross-sectional front view of a waste incinerator, FIG. 2 is a vertical cross-sectional front view of a dust supply device, FIG. 3 is a plan view of the dust supply device, and FIG. 4 is a front view of a dust supply device. 2, FIG. 5 is a cross-sectional view taken along the - line in FIG. 2, FIG. 6 is a view at another point in time, FIGS.
The figure is a hydraulic circuit diagram, Figure 9 is a vertical cross-sectional diagram of the incinerator,
FIGS. 10a and 10b are a plan view and a side view of the hearth module of the present invention, FIG. 11 is an explanatory diagram of the flow state in the furnace, and FIGS. 12a and b are a plan view and a side view of a conventional hearth module. It is. 1...garbage pit, 2...crane, 3...bucket, 4...hopper, 5...dust supply device, 6...
...Incinerator, 7...Blower, 8...Dispersion plate, 9...
Inclined wall, 10...Swirling flow, 11...Combustion exhaust gas duct, 12...Incombustibles discharge device, 13...Vibration sieve, 14...Conveyor, 15...Elevator, 1
6...Inlet, 17...Exit, 20...Conveyor case, 21, 22...Screw, 23, 24...
...Blade, 25, 26...Bearing, 27...Motor,
28, 29... Cylinder, 30... Guide rail, 31, 32... Moving bearing, 33, 34... Link, 35, 36, 37, 38... Gear, 39...
...Garbage, 42...Incombustible material outlet, 43, 44, 4
5... Air chamber, 46... Inclined surface, 47... Ceiling, 48... Raw material input port.

Claims (1)

[Scope of Claims] 1. A fluidizing dispersion plate is provided, and the dispersion plate has both side edges lower than the center part and is formed in a chevron-shaped cross section that is substantially symmetrical with respect to the center line, and the dispersion plate is formed to have a chevron-shaped cross section that is substantially symmetrical with respect to the center line, and the fluidizing gas at the both side edges is lower than the center. A plurality of sets of fluidized bed thermal reaction sections having a mass velocity higher than the fluidizing gas mass velocity in the central part are arranged in parallel at the bottom of the same furnace, and a common incombustible material discharge port is provided between each of the dispersion plates. Inflammable material discharge ports are provided on each of the outer side edges, and reflecting walls are provided directly above both side edges of each of the dispersion plates to reflect and divert the upward flow of fluidized gas toward the center of each fluidized bed thermal reaction section. A raw material inlet is provided in the furnace ceiling so as to correspond to the center of each distribution plate, and the furnace space surrounded by the furnace wall, the distribution plate, and the ceiling has a reflecting wall inside the furnace. A fluidized bed thermal reactor characterized in that it is formed as an integral space. 2. The fluidized bed thermal reactor according to claim 1, wherein the fluidizing gas mass velocity at the center of each of the distribution plates is 0.5 to 3 Gmf. 3. The fluidized bed thermal reactor according to claim 1 or 2, wherein at least two raw material input ports are provided.