JPH1054518A - Combustion melting furnace and waste treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the operation negative pressure in a combustion melting furnace from increasing by making up for pressure loss required to form a swirling flow by means of a forced draft fan provided in a pyrolysis gas passage connected to an inlet nozzle of the combustion melting furnace. SOLUTION: A mixture of porolysis gas introduced into a furnace 9a and air is burnt, while the mixture is being formed into a swirling flow 42. If an attempt is made to increase the velocity of the flow 42 to heighten a ratio of slag formation, pressure loss resulting from the formation of swirling flow increases so that operation negative pressure of a waste heat boiler, dust collector, and exhaust gas treatment device provided downstream of a combustion melting furnace 9 increases, corresponding to an increase in the pressure loss and a negative pressure resistant strength for these devices increases. Hence a forced draft fan 8 is provided in a pyrolysis gas passage (line L3) connected to an inlet nozzle 30 of the furnace 9 to make up for pressure loss required to form the flow 42 by means of the fan 8. Thus design negative pressure for the furnace 9 and downstream side devices can be held at an ordinary value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste treatment apparatus and, more particularly, to a waste treatment apparatus provided with a combustion melting furnace for burning a pyrolysis gas obtained by thermally decomposing waste containing a combustible substance. Here, waste is general waste such as municipal waste from homes and offices, waste plastic, car shredder dust, waste office equipment, electronic equipment,
Includes combustibles such as chemical products.

[0002]

2. Description of the Related Art Various types of waste treatment apparatuses have been proposed as waste treatment apparatuses for treating various wastes including general wastes such as municipal waste and combustibles such as waste plastics by incineration and the like. For example, according to the waste treatment apparatus described in Japanese Patent Publication No. 6-56253, first, waste is thermally decomposed by heating it in a low oxygen atmosphere, and then gas and solid (hereinafter, referred to as pyrolysis residue). The pyrolysis gas is led to a combustion melting furnace for combustion treatment, and the combustion waste heat is recovered by a waste heat boiler. On the other hand, the pyrolysis residue is appropriately separated into components according to the size, such as fine fine-grained components, slightly fine coarse-grained components, and slightly coarse coarse-grained components, by a separation device such as a sieve. Then, the pyrolysis residue composed of the fine-grained component and the slightly fine-grained component is sent to the above-mentioned combustion melting furnace and incinerated with the pyrolysis gas. Most of the combustion residues generated in this incineration process, that is, most of the non-combustible components such as ash, are melted by combustion heat to become molten slag. Most of the incombustible fly ash carried along with the pyrolysis gas is also melted by the heat of combustion in the combustion melting furnace to become molten slag. This molten slag is discharged from the bottom of the combustion melting furnace and solidified by cooling. On the other hand, fine incombustible components (hereinafter referred to as dust) such as fly ash which are not melted in the combustion melting furnace and are discharged together with the combustion exhaust gas are, for example, waste heat disposed in the latter stage of the combustion melting furnace. The collected dust is collected in a boiler, an exhaust gas cooling tower, an exhaust gas filtration device, or the like, and the collected dust is returned to a combustion melting furnace to be melted and turned into slag.

[0003] In this way, the fine components or relatively fine coarse components of the pyrolysis residue, and dust such as fly ash collected by an exhaust gas filtration device and the like are melted in a combustion melting furnace. Thereafter, the mixture is cooled and solidified to form a shape or the like that can be easily handled.

[0004]

In the above-mentioned waste treatment apparatus, non-combustible components (non-combustible fine components or relatively fine coarse components and dust such as fly ash, etc.) which flow into the combustion melting furnace. It is preferable that the ratio of the amount of molten slag or solidified slag to the amount of inflow of slag (hereinafter referred to as slag conversion ratio) is large. However, the technique described in the above publication does not consider improving the slag conversion rate.

On the other hand, in a configuration in which a pyrolysis gas is introduced into a melting furnace from a furnace top of a combustion melting furnace through a short body tube, a swirler (swing blade) is provided in the short body tube to heat the inside of the furnace. It has been studied to improve the slag conversion rate by swirling the decomposition gas. That is, the pyrolysis gas is swirled in the combustion melting furnace to substantially increase the residence time of the non-flammable components flowing into the combustion melting furnace, or the non-flammable components are brought into contact with or captured by the furnace wall by the centrifugal force of the swirling. In this way, the slag conversion rate is improved by promoting the slag conversion of the non-combustible component by the slag formation.

However, if the slag conversion rate is increased by increasing the flow velocity of the swirling flow, the pressure loss associated with the formation of the swirling flow increases. Accordingly, the negative pressure in the combustion melting furnace increases, and the combustion melting temperature increases. A problem arises in that the pressure resistance of the furnace must be increased. Particularly, in order to conduct heat recovery and exhaust gas treatment by conducting the flue gas generated in the combustion melting furnace to related equipment such as a waste heat boiler and an exhaust gas filtration device, an induction blower is installed at the last stage of the related equipment. The flue gas is passed through the device. Therefore, it is desirable to avoid increasing the negative pressure in the combustion melting furnace because the operating negative pressure of the downstream related devices must be further increased and the negative pressure strength of those devices must be increased.

An object of the present invention is to suppress an increase in the operating negative pressure in the combustion melting furnace when increasing the swirling flow rate in the combustion melting furnace to improve the slag conversion rate.

[0008]

In order to solve the above-mentioned problems, the present invention provides a forced blower in a pyrolysis gas flow path connected to an inlet nozzle of a combustion melting furnace, and forms a swirling flow by the forced blower. In this case, the increase in the operating negative pressure in the combustion melting furnace is suppressed by compensating for the pressure loss required for the combustion furnace. As a result, a sufficiently fast swirling flow required for improving the slag conversion rate can be formed.

[0009] The swirling flow can be formed by introducing a pyrolysis gas into the furnace through a short body tube provided through the furnace top wall and having swirling blades therein. Further, by providing a short body tube for penetrating the upper part of the furnace side wall and introducing the pyrolysis gas into the combustion melting furnace, and providing the tube axis of the short body tube in a tangential direction with respect to the furnace radial direction, the furnace is provided. A swirling flow can be formed in the inside.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a configuration diagram of an embodiment of a combustion melting furnace according to the features of the present invention, respectively, and a system diagram of an embodiment of a waste treatment apparatus to which the present invention is applied.

Basically, as shown in FIGS. 1 and 2, in a combustion melting furnace 9 according to the present invention, a burner 11 is provided at the top of a cylindrical furnace body, and is connected to an inlet nozzle 30 of the burner 11. A forced blower 8 is inserted into the flow path (line L3) of the pyrolysis gas thus formed, and the pyrolysis gas generated in the pyrolysis reactor 6 is supplied via the forced blower 8. Further, a combustion exhaust gas outlet nozzle 40 provided at the bottom of the combustion melting furnace 9 is connected to the induction blower 24 via the waste heat boiler 21 and the like as shown in FIG.

Here, a detailed configuration of the combustion melting furnace will be described with reference to FIG. The burner 11 includes a short body tube 31 having an inlet nozzle 30 into which the pyrolysis gas is introduced, an air nozzle 32 coaxially inserted into the short body tube 31, and a short body tube 3.
1 and a swirling blade 33 provided at a lower end portion. The burner 11 is attached such that the lower part of the short body tube 31 is inserted into a through hole formed in the center of the furnace top wall, and the lower end opening of the short body tube 31 faces the inside of the furnace. A heat insulating material 34 is provided between the outer periphery of the short body tube 31 and the furnace top wall, and a heat insulating material 35 is also provided on the outer periphery of the air nozzle 32 located inside the short body tube 31. The swirl vanes 33 swirl the pyrolysis gas introduced from the inlet nozzle 30 to make the furnace 9
a, for example, a plurality of blades are formed in a radial arrangement by being inclined in accordance with the turning direction.

An outlet nozzle 40 for the combustion exhaust gas of the combustion melting furnace 9 is provided in communication with the induction blower 24, and a discharge port 16 provided at the bottom is provided with a water tank 17 filled with water 41.
It is located under the surface of the water. In addition, the combustion melting furnace 9 has a pilot burner 36, an appropriate number of air nozzles 37 for secondary air, a charging nozzle 38 for charging the combustible component d supplied from the crusher 14 into the furnace, and a crusher 19. Nozzle 3 into which non-metallic component e ₂ supplied from
9 are provided. Although not shown, an appropriate number of air nozzles for supplying tertiary air can be provided below the furnace.

The operation of the combustion-melting furnace thus configured will be described focusing on the generation of molten slag. Burner 1
The pyrolysis gas G1 supplied to 1 is blown out from the short body tube 31 through the swirl vanes 33 into the furnace 9a. At this time, it is mixed with the primary air supplied through the air nozzle 32,
Further, the swirling blade 33 receives the swirling force and blows out into the furnace 9 a, and is ignited by the pilot burner 36. Thereby, the mixture of the pyrolysis gas and the air introduced into the furnace 9 a is burned while forming the swirling flow 42. Due to this combustion temperature (for example, about 1300 ° C.), the incombustible ash introduced along with the pyrolysis gas and the combustion ash of the combustible component d supplied from the injection nozzle 38 are melted,
The molten slag f is formed along with the swirling flow 42 or pushed toward the furnace wall by the centrifugal force of the swirling flow 42 and adheres to the inner wall of the furnace. Then, the non-metallic component e ₂ supplied from the charging nozzle 39 is similarly melted and mixed into the molten slag f flowing down the inner wall of the furnace. The molten slag f thus formed flows down along the inner wall of the furnace and flows down through the outlet 16 at the bottom.
From the water tank 17 and is cooled and solidified.

The amount of the molten slag f formed in this manner increases when the flow velocity of the swirling flow 42 is increased.
The present inventors have confirmed empirically. This is because, when the flow velocity of the swirling flow 42 is increased, the non-combustible components increase in accordance with the residence time of the non-combustible component in the combustion melting furnace. It is considered that the conductive component is carried toward the furnace wall. However, when trying to increase the slag conversion rate by increasing the flow velocity of the swirling flow 42, the pressure loss associated with the formation of the swirling flow increases, and the waste heat provided downstream of the combustion melting furnace 9 is reduced by the pressure loss. The operation negative pressure of the boiler 21, the dust collector 22, and the exhaust gas treatment device 23 increases, which causes a problem that the mechanical strength of the components must be increased in order to increase the negative pressure resistance of the devices.

Therefore, according to the present invention, a forced blower 8 is provided in the pyrolysis gas flow path (line L3) connected to the inlet nozzle 30 of the combustion melting furnace 9, and the forced blower 8 is required to form the swirl flow 42. The pressure loss was compensated for. That is, the normal operating negative pressure of the combustion melting furnace 9 is 3
If the pressure loss for obtaining the required flow velocity of the swirling flow 42 is 0 mmAq, for example, and the pressure loss is 50 mmAq, the operation negative pressure of the combustion melting furnace 9 will be 80 mmAq. Therefore, if the blower 8 is provided on the inlet side of the combustion melting furnace 9 to compensate for the pressure loss of 50 mmAq, the designed negative pressure of the combustion melting furnace 9 and the downstream device can be maintained at a normal value.
As a result, the necessary and sufficiently fast swirling flow 42 can be formed, so that the slag conversion rate can be improved.

The overall structure of a waste treatment apparatus to which the combustion melting furnace configured as described above is applied will be described with reference to FIG. The waste a carried into the waste receiving yard A is the first waste.
Is sent to the crusher 1 by the conveyor 2 of
After being pulverized to a size equal to or less than mm, it is supplied to the input port 4 of the screw feeder 5 by the second conveyor 3. The waste supplied to the screw feeder 5 is introduced into a rotary drum type pyrolysis reactor 6, where the waste a is 300
C. to about 600.degree. C. (usually 450.degree. C.), thereby being thermally decomposed. This heating is performed by a plurality of heating tubes arranged along the inner peripheral wall of the rotary drum of the pyrolysis reactor 6, and the heating tubes are supplied with heated air via a line L1. Further, the internal pressure of the thermal decomposition reactor 6 is maintained at an atmosphere lower than the atmospheric pressure. Then, the pyrolysis gas and the pyrolysis residue generated in the pyrolysis reactor 6 are guided to the discharge device 10, and the pyrolysis residue G1 is sent to the burner of the combustion melting furnace 9 through the line L ₉ and the push-in blower 8. The thermal decomposition residue (mainly a non-volatile component) b is supplied to the cooling device 12, cooled to about 80 ° C. in the cooling device 12, and then sent to the separation device 13.

As the separation device 13, a known separation device such as a sieve, a magnetic separation type, an eddy current type, a centrifugal type or a wind separation type is used, and a flammable component d such as pyrolytic carbon and a non-combustible component are used. It is separated into a certain metal component e1 and a non-metal component e2. Note that the combustible component d includes non-combustible components such as fine ash. The separated components are discharged to the corresponding containers or hoppers 18a, 18b, 18c.

The combustible component d discharged to the hopper 18c
Is pulverized to, for example, 1 mm or less by a pulverizer 14, and supplied to the combustion burner 11 of the combustion melting furnace 9 via a line L4. Further, the non-metal component e discharged to the hopper 18b
Part or all of 2 is pulverized by a pulverizer 19 and supplied into the combustion melting furnace 9 via a line L6.

The burner 11 of the combustion melting furnace 9 has a line L3
Is burned by the blower 15 with the combustion air F supplied from the line L5. At this time, the mixture of the pyrolysis gas and the combustion air burns while forming a swirling flow in the combustion melting furnace 9. The combustion temperature is set in a high temperature range of about 1300 ° C., which is higher than the melting temperature of the ash. Due to this combustion temperature, the non-combustible ash introduced along with the pyrolysis gas and the combustion ash of the combustible component d supplied from the crusher 14 move toward the furnace wall by the above-mentioned swirling flow. The molten slag is captured by the furnace wall while being melted by the slag. The molten slag flows down the furnace inner wall to the outlet 16 at the bottom, from which it falls into the water tank 17 to be cooled and solidified. This solidified slag is used as a building material such as a pavement material.

The high-temperature flue gas G2 generated in the combustion melting furnace 9 is guided to a heat exchanger (high-temperature air heater) (not shown), and heats the heating air flowing through the heating pipe of the above-described pyrolysis reactor 6. After that, it is supplied to the waste heat boiler 21 via the line L7. The waste heat boiler 21 generates steam by the heat of the combustion exhaust gas, thereby rotating the steam turbine generator 24 to recover power. The combustion exhaust gas G2 discharged from the waste heat boiler 21 is guided to a dust collector 22 to be dust-removed, and further, is cleaned at a low temperature by a gas purification device 23.
And is discharged to the atmosphere from the chimney 25 via the induction blower 24. Part of this clean flue gas G3
The cooling medium is supplied to the cooling device 12 via a line L8.

The dust g collected by the dust collector 22
Is returned to the combustion / melting furnace 9 via the line L9 to be converted into molten slag. The dust collected in the waste heat boiler 21 may be returned to the combustion and melting furnace 9 in the same manner. Further, these dusts are substantially removed from the pyrolysis reactor 6.
May be returned to the crusher 14 or the like.

In the embodiment shown in FIG. 1, the swirling flow 42 is formed in the furnace by the swirling blades 33. However, the present invention is not limited to this, and the structure shown in FIG. A desired swirl flow can be formed. FIG. 3A shows an upper cross section of the combustion melting furnace 9, and portions not shown in the drawing are the same as those in FIG. 2. The difference from FIG. 2 is that the swirl vanes 33 of the burner 11 are removed and the mounting position is on the side wall near the furnace top.
As shown in (b), the tube shaft 45 of the short body tube 31 is attached at an angle α in a tangential direction 47 with respect to the furnace radial direction 46. With such a configuration, it is known that, similarly to a cyclone or the like, the pyrolysis gas blown out from the burner 11 forms a swirling flow along the furnace wall.

The temperature of the pyrolysis gas flowing through the forced air blower 8 according to the present invention is 300 to 600 ° C.
Therefore, the push-in blower 8 should be one that withstands the temperature. In particular, in order to avoid conduction of heat through the drive shaft to the motor that drives the push-in blower 8, a non-contact type that drives the blades of the blower through a non-contact type magnetic coupling means is applied. Is preferred.

Although the present invention has been described in detail with reference to the illustrated embodiments, the present invention is not limited to only those embodiments, and various modifications may be made without departing from the spirit of the present invention. It goes without saying that various modifications can be made.

[0026]

As described above, according to the present invention, an increase in negative pressure in a combustion melting furnace can be suppressed, and a required sufficiently fast swirling flow can be formed. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of a combustion melting furnace of the present invention.

FIG. 2 is a system diagram of an embodiment of a waste treatment apparatus to which the combustion melting furnace according to the present invention is applied.

FIG. 3 is a sectional view of another embodiment of the combustion melting furnace of the present invention.

[Explanation of symbols]

 Reference Signs List 6 Pyrolysis reactor 8 Push-in blower 9 Combustion melting furnace 11 Burner 30 Inlet nozzle 31 Short body pipe 33 Swirl vane 42 Swirl flow

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display F23L 5/02 F23L 5/02

Claims (4)

[Claims] 1. A pyrolysis gas generated by thermally decomposing waste is introduced into a furnace through an inlet nozzle, and the pyrolysis gas is burned while being swirled in the furnace, and the combustion exhaust gas is communicated to an induction fan. A combustion / melting furnace discharged from an outlet nozzle provided with a blower inserted into a pyrolysis gas flow path connected to the inlet nozzle. 2. The combustion melting furnace according to claim 1, wherein
The combustion melting furnace, wherein the pyrolysis gas introduced from the inlet nozzle flows into the furnace through a short body tube provided through the furnace top wall and having swirling blades therein. 3. The combustion melting furnace according to claim 1, wherein
The pyrolysis gas introduced from the inlet nozzle is introduced into the combustion melting furnace through a short body tube provided through the upper part of the furnace side wall, and the tube axis of the short body tube is relative to the furnace radial direction. A combustion melting furnace characterized by being provided tangentially inclined. 4. A pyrolysis reactor for heating and thermally decomposing waste to produce a pyrolysis gas and a pyrolysis residue, and separating the pyrolysis residue into a flammable component and a non-flammable component. An apparatus, a combustion melting furnace for burning the pyrolysis gas and the combustible component to generate a molten slag and a combustion exhaust gas, and an induction blower for extracting the combustion exhaust gas from the combustion melting furnace, wherein the combustion melting furnace In a waste treatment apparatus in which the introduced pyrolysis gas is burned while swirling in a furnace, the pyrolysis gas is forced into a flow path of the pyrolysis gas to communicate with the pyrolysis reactor and the combustion melting furnace. A waste treatment device comprising a blower.