JPH0252166B2 - - 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.

[Conventional technology]

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

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. A fluidized bed thermal reactor, disclosed in Japanese Patent Application Laid-Open No. 124608/1982, was invented as a solution to the conventional drawbacks by circulating a fluidized medium to form a fluidized bed and a moving bed.

[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 formed in a chevron-shaped cross section that is substantially symmetrical with respect to the center line, and the fluidizing gas mass velocity at the both side edges is Fluidized bed thermal reaction sections in which the fluidization gas mass velocity is larger than the fluidized gas mass velocity in the central portion are arranged in parallel at the bottom of the same furnace almost symmetrically with respect to the furnace center line, and a common non-combustible A non-combustible material discharge port is provided at each outer side edge, and an upward flow of fluidizing gas is directed directly above the side edge of each distribution plate on the furnace wall side at the center of each fluidized bed thermal reaction section. Each of the furnaces is provided with a reflecting wall that reflects and deflects toward the furnace, and a raw material inlet is provided in the furnace ceiling so that the raw material is introduced onto the layer above the common non-combustible material discharge port between the dispersion plates and the layer in the vicinity thereof. This is a fluidized bed thermal reactor characterized by:

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings in an embodiment 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 furnace, and the swirling fluidized bed and descending moving bed cause the waste to burn well in a short period of time, and even if crushing is not performed in advance, fluidization is inhibited. It is possible to obtain high combustion efficiency.

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 introduced 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, at the bottom of the incinerator 6, two sets of air dispersion plates 8 for fluidization are arranged side by side on the left and right, almost symmetrically with respect to the center line of the furnace. Both side edges are lower than the center and are formed into a chevron-shaped cross section (roof-like) that is approximately symmetrical with respect to the center line. The inclination may be different between the center portion and both side edge portions. Noncombustible material discharge ports 42 are connected to both side edges, and one of the noncombustible material discharge ports 42 between the respective distribution plates 8 at the center of the furnace is shared.

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 and 45 is 4 to 20 Gmf, preferably 5 to 10 Gm.
mf, 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, on the side edge of the dispersion plate 8, directly above the air chamber 43 on the furnace wall side, there is an inclined wall 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. 9 is provided, and the upper side of the inclined wall 9 is provided with an inclined surface 46 having an opposite slope to the inclined wall 9.
are provided to prevent the flow medium from accumulating. Further, 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 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, the furnace ceiling 47 is connected to the outlet 17 of the dust supply device 5 so that the raw material is fed onto the layer on the common incombustible material discharge port 42 between the dispersion plates 8 and the layer in the vicinity thereof. A raw material input port 48 is provided.

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 in particular the fluidized medium on the air chamber 43 hits the inclined wall 9 and is reflected and turned upward while facing the center of the furnace, 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 part of the fluidized medium is swirled and circulated in the fluidized bed as a swirling flow 10, and in the center of the furnace, fluidization is performed only in the upper and lower portions, similar to a normal fluidized bed.

That is, the swirling flow 10 of the fluidized medium occurs above the air chamber 43 on the furnace wall side, and since there is no barrier above the air chamber 45 on the furnace center side, the state is the same as that of a normal fluidized bed with upstream and downstream flow.

In the incinerator 6 in this state, there is a common incombustible material discharge port 42 between the raw material input port 48 and the distribution plate 8.
Garbage is dumped onto the top of a strong normal fluidized bed that forms at the top nearby. Among the input garbage, those with relatively high specific gravity are taken into the normal fluidized bed near the center, and those that are easily combustible are combusted. Flame-retardant materials are partially dried or combusted and diffused into the swirling flow 10. In addition, garbage with a relatively light specific gravity is usually not caught up in the fluidized bed, but is scattered and burned in the freeboard, and garbage that cannot be burned is diffused into the swirling flow section.
It falls and gets caught up in the swirling flow 10. swirl flow 10
In this part, the flow of the fluid medium flows from the outside toward the center in a concentrated direction, so that the debris is caught up in this flow and sinks 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 unlike in conventional fluidized beds, the paper does not burn on the fluidized medium and contribute greatly to the heating of the fluidized medium. It is possible to prevent combustion and reliably perform combustion in the normal fluidized bed, descending moving bed, and swirling flow 10 to heat the fluidized medium.

In the descending moving bed, thermal decomposition occurs partially and combustible gas is generated, and this generated combustible gas diffuses horizontally and usually enters the fluidized bed where it is combusted.
The heat serves effectively to heat the fluid medium.

When heavy and large objects such as bottles and irons are dropped onto the surface of the normal fluidized bed in the center of the furnace, these objects are supported by the fluidized medium that is fluidized by the updrafts blown up in the air chamber 45. It gradually descends, moves to the incombustible material discharge port 42 in the center of the furnace, and is discharged. During this time, combustible materials (such as the covering of electric wires) that are attached to non-combustible materials or that are integrated with them are burned.

Therefore, even if the combustible material is of a considerable size, it dries, gasifies, and burns as it moves, and by the time it reaches the incombustible material outlet in the center of the furnace, most of it has been burned and broken into small pieces. , does not inhibit the formation of a fluidized bed.

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.

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

〔Effect of the invention〕

As described above, according to the present invention, municipal waste,
In an incinerator or pyrolysis furnace that efficiently burns 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 a furnace with a large furnace width. Even in this case, it is possible to keep the moving distance of non-combustibles short and prevent the non-combustibles from accumulating.
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,
FIG. 10 is 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 FIG.
Figures 2a and 2b are a plan view and a side view of a conventional hearth module. 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...Outlet, 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 inlet.

Claims (1)

[Claims] 1 A dispersion plate for fluidization is provided, and the dispersion plate is formed in a chevron-shaped cross section that is substantially symmetrical with respect to the center line, with both side edges lower than the center, and the fluidization gas mass velocity at the both side edges is lower than the center. A fluidized bed thermal reaction section with a fluidization gas mass velocity larger than the mass velocity of the fluidized gas in the section is arranged in parallel at the bottom of the same furnace almost symmetrically with respect to the furnace center line, and a common incombustible material discharge port is provided between each of the distribution plates. At the same time, an incombustible material discharge port is provided on each outer side edge, and an upward flow of fluidizing gas is directed directly above the side edge on the furnace wall side of each distribution plate toward the center of each fluidized bed thermal reaction section. Each of the furnaces is provided with a reflecting wall for reflecting and turning the material, and furthermore, a material inlet is provided in the furnace ceiling so that the material is introduced onto the layer above the common incombustible material outlet between the dispersion plates and the layer in the vicinity thereof. Characteristic fluidized bed thermal reactor.