JPH0611124A - Waste melting furnace and waste feeding method - Google Patents

Abstract

PURPOSE:To suppress the generation of dispersing dust and to uniform temp. in a furnace by a method wherein a droop wall protruded downward from the upper part side of a combustion space is provided in a boundary position between a combustion space and a filled layer. CONSTITUTION:A lowering guide surface 8a being a slope which is protruded downward from the upper part side of a combustion space 4 positioned more upward on the combustion space 4 side with the increase of separation of it from a coke-filled layer 2 is formed in a boundary position between the combustion space 4 and a coke-filled layer 2. A droop wall 8 made of refractories having the lowering guide surface is provided. Thus, combustion gas in the combustion space 4 is further delayed in an advection current to the interior of the coke-filled layer 2 compared with a case having no droop wall 8, and the flow direction of combustion gas to the interior of the coke-filled layer 2 is set to an oblique down direction. This method uniformizes temperature distribution in sectional direction of the interior of the filled layer and reduces dispersion of dust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a case where powdered waste such as sludge is blown into a packed bed formed of a carbon-based combustible material such as coke to burn the waste and form molten slag. The present invention relates to a waste melting furnace proposed for the purpose of preventing the scattering of dust generated during processing and reducing fuel consumption. More specifically, the present invention relates to a waste melting furnace, which includes a packing layer formed of a carbon-based combustible substance. An annular combustion space communicating with the packed bed is provided in the outer peripheral portion of the packed bed at a position lower than the upper surface of the, and the waste is blown into the combustion space in the form of powder to generate waste in the combustion space and the packed bed. TECHNICAL FIELD The present invention relates to a waste melting furnace that burns fuel and turns it into molten slag, and a method of supplying waste to the waste melting furnace.

[0002]

2. Description of the Related Art When powder-like waste such as sludge is blown into a high-temperature hearth for combustion and melting, if direct blown into the packed bed, the waste (sludge) will adhere to the surface of the coke. The temperature of the packed bed is lowered due to combustion inhibition, endothermic phenomenon due to decomposition of organic components, and the like. As a result, clogging by waste dust in the furnace progresses, and the operation of the furnace deteriorates. Therefore, as shown in FIG. 3B, in order to eliminate these adverse effects, an annular combustion space is artificially provided in the peripheral portion of the packed bed, and the combustion gas is sent laterally from this combustion space toward the packed bed. Then, a method of burning and melting the above waste has been considered (Japanese Patent Application No. 2-131746).
issue).

[0003]

However, according to the above-mentioned structure, the waste powder blown in should be melted or turned into char after burning in the combustion space and turned into molten slag in the coke layer and discharged from the outlet. However, in some cases, they are not actually collected in the coke layer and may be scattered as dust in the exhaust gas. Further, in such a combustion / melting structure, since there are many peripheral flows in the packed bed, only the peripheral wall wrinkles become high in temperature. The reason for this is considered to be "peripheral fluidization phenomenon" in the normal packed bed structure. That is, in the packed bed structure, the gas blown from the tuyere easily flows through the wall around the center of the furnace, and in the blast furnace for iron making, the peripheral wind speed is said to be more than twice the central wind speed. This phenomenon becomes more remarkable when the filling layer structure is thin as in the present application. As a result, it is considered that the powdered waste that was blown in is scattered in the exhaust gas that passes through the walls and that the temperature of the furnace center does not rise sufficiently because the gas flow to the furnace center is low. Has to be non-uniform.

As a result, the following problems may occur in such a waste melting furnace. 1. Dust scattering (short path for powder waste) 2. Bridge formation in packed bed due to uneven temperature in the furnace. 3. Increase in coke consumption due to partial combustion of peripheral coke and unburned powder waste. Poor slag due to unstable furnace operation

Therefore, an object of the present invention is to obtain a waste melting furnace in which the generation of scattered dust can be suppressed as much as possible, the temperature inside the furnace is uniform, and the disposal efficiency of waste is high, and at the same time, this object is improved. To obtain a waste supply method that can be achieved.

[0006]

To achieve this object, the waste melting furnace according to the first aspect of the present invention is characterized in that it is projected downward from the upper side of the combustion space at the boundary position between the combustion space and the packed bed. In addition, the waste melting furnace according to the second aspect of the present invention is characterized in that the flow direction of the combustion gas advancing from the combustion chamber to the packed bed is set obliquely downward. It is in. Further, in the configurations of the first and second inventions, a supply means for supplying the waste to the combustion space from a plurality of introduction sites dispersed in the circumferential direction is provided, and the supply direction of the waste by the supply means is an annular shape. It is preferable that the combustion space is set so as to form a swirling flow. Then, in the waste melting furnace of such a configuration, as a waste supply method, waste is sequentially supplied in the circumferential direction of the combustion space at a plurality of introduction sites, and the waste supply is stopped to form in the combustion space. It is preferable to accelerate or suppress the swirling of the swirling flow. The actions and effects thereof are as follows.

[0007]

First, in the waste melting furnace of the first and second configurations, the powdery waste blown into the combustion chamber is lowered by providing the hanging wall or controlling the flow direction of the combustion gas. And penetrates inside the packed bed. Then, the combustion treatment on the central side of the packed bed is promoted, and the temperature distribution in the transverse direction in the packed bed is made uniform. In addition, the amount of waste processed by combustion increases (dust scattering decreases)
As a result, the processing temperature also rises. Therefore, it is possible to prevent the wall side blow-through in which the waste material is short-circuited and rises from the combustion space to the vicinity of the side wall of the packed bed as in the conventional case. On the other hand, the combustion gas in the annular combustion space will be sent into the packed bed while drawing a swirling locus around the packed bed in this space, but depending on the drooping wall or the control of the flow direction corresponding to this, A sufficient residence time in the combustion space can be taken, and the treatment of waste in this space is promoted more than before. As a result, in the waste melting furnace of the present application, complete combustion of combustibles and temperature rise due to combustion can be achieved,
The furnace can be easily maintained at a predetermined temperature and the operation can be performed stably. Here, when the waste introduction site is limited to one place, non-uniformity of the combustion space form or the like may occur due to partial wear of the refractory material at the blow-in portion (introduction site). When such non-uniformity occurs, the non-uniformity of combustion,
In some cases, a decrease in melting ability may be induced. Therefore, it is preferable that a plurality of blow-in points are provided in the circumferential direction of the annular combustion space to be dispersed. Further, when the supply means is operated in supplying the waste, when controlling the supply order, supply timing, etc. of the waste at each introduction site, the state of the swirling flow formed in the combustion space can be easily controlled.
Then, by promoting or suppressing the temperature rise and drying process of the waste in the combustion space, it is possible to make the processing state of this part in line with the operating conditions of the entire furnace, and the overall good processing is performed. Can continue.

[0008]

As described above, in the waste melting furnace of the present invention, the short path of the waste can be prevented, and as a result, the amount of dust scattering of the waste is reduced. Further, the combustion in the combustion chamber was promoted and the temperature became high, and the temperature of the packed bed in the furnace was made uniform and the operation was stabilized. Due to the various factors mentioned above, carbon-based combustible substances, which are materials that can prevent the generation of bridges due to partial melting of waste in the high temperature part and dust adhesion in the low temperature part, and that constitute the packed bed accompanying waste disposal The fuel consumption of (for example, coke) was reduced. Furthermore, by adopting a unique supply configuration, combustion in the combustion space can be made stable, and the combustion state in this space can be easily controlled.

[0009]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a cross-sectional view in the vicinity of a coke packed bed 2 which is a packed bed of the waste melting furnace 1. As shown in the figure, the waste melting furnace 1 is provided with a coke packing layer 2 having a substantially vertical cylindrical shape, and the coke packing layer 2 has a slag port through which molten slag is slagged at a lower position thereof. 3 is provided, and an annular combustion space 4 is provided at a position lower than the upper surface of the coke packed layer 2 at an outer peripheral portion in the transverse direction thereof, and a freeboard 5 is provided at an upper portion of the coke packed layer 2.
It is configured with. A primary air supply nozzle 6 for supplying primary air to the coke-filled layer 2 and a secondary air supply nozzle 7 for supplying secondary air to this portion near the inlet of the freeboard 5 are provided. And are provided.

Next, the combustion space 4 will be described. To the combustion space 4, a waste supply nozzle 4a for supplying sludge, which is a waste in powder form, by carrier air, and an oxygen-containing gas are blown. Oxygen-containing gas supply nozzle 4
b, an auxiliary fuel injection nozzle 4c for injecting auxiliary fuel is provided. Therefore, in this combustion space 4,
While the fuel is burning, the powdery sludge sent into the combustion space 4 is dried and burned, and the generated combustion gas swirls around the coke packed layer 2 along with unburned matter. Coke filling layer 2 while drawing
Sent in.

Further, at the boundary position between the combustion space 4 and the coke packed layer 2, the lower side of the combustion space 4 is projected downward.
A downward guide surface 8a, which is an inclined surface located upward as it is separated from the coke filling layer 2 on the combustion space 4 side,
A hanging wall 8 made of refractory is provided. Therefore, in the waste melting furnace 1 of the present application, by providing the hanging wall 8, the combustion gas in the combustion space 4 enters the coke filling layer 2 as compared with the case where the hanging wall 8 is not provided. The advection is delayed (the swirling amount increases) and the coke packed bed 2
The flow direction of the combustion gas inward is set to be obliquely downward.

Further, the supply structure of sludge, oxygen-containing gas and auxiliary fuel, which are wastes, to the combustion space 4 will be described. FIG. 2 shows a cross-sectional view of the combustion space 4 at the position. As shown in the figure, the supply device 40 equipped with the waste supply nozzle 4a, the oxygen-containing gas supply nozzle 4b, and the auxiliary fuel injection nozzle 4c (the latter two have a single nozzle in common) has an annular shape. 4 are evenly distributed around the combustion space 4 and the blowing directions thereof are respectively set to the tangential direction of the annular combustion space 4. As a result, the sludge in the air-carrying state, the oxygen-containing gas, and the auxiliary fuel supplied from the supply device 40 are transferred to the combustion space
To form a swirling flow F in a fixed direction (clockwise in the illustrated example). Now, a control device 41 is provided for these supply devices 40, and the supply (supply of sludge, oxygen-containing gas, auxiliary fuel gas) in each supply device 40, supply stop control, or supply amount control is performed. Has been adopted. Regarding the supply and supply stop control, by controlling the blowing timing in each supply device 40, the swirling of the swirling flow formed in the combustion space 4 can be accelerated or suppressed. That is, when it is desired to accelerate the turning, the blowing timings from the respective supply devices 40 along the circumferential direction are sequentially advanced, and when the turning is to be suppressed,
By limiting the blowing to a part of the supply device 40 and performing operations such as slowing the blowing speed,
This control can be performed. Such control can also be performed by adjusting the supply amount by each supply device 40.
Therefore, the processing in the combustion space 4 can be controlled according to the combustion conditions in the combustion space 4 and the packed bed 2 to make the operating condition of the entire furnace stable and well controlled.

Further, each of the supply devices 40 has a first introduction path 43a for guiding the powdery sludge to the corresponding introduction site 42.
And a second introduction passage 43b which is formed in the peripheral portion of the first introduction passage 43a and guides the oxygen-containing gas or a mixed gas of the oxygen-containing gas and the fuel gas to the vicinity of the introduction portion 42. Then, the linear first and second introduction paths 43
In contrast to a and 43b, the oxygen-containing gas or the mixed gas is supplied at the base end side of the second introduction passage 43b from the direction orthogonal to the introduction passage 43b, and flows in the annular passage while drawing a spiral locus. Has been adopted. Therefore, the introduction portions 4 located on the tip side of the nozzles 4a, 4b, 4c
In 2, the oxygen-containing gas or mixed gas is supplied as a spiral swirl flow around the sludge carrier flow. Therefore, sludge and oxygen-containing gas (which may include fuel gas) in the combustion space 4 are effectively diffused and mixed. In the above description, a system for supplying at least waste to the combustion space 4 at the plurality of introduction sites 42 dispersed in the circumferential direction of the space is referred to as a supply means. Further, an oxygen-containing gas (which may include a fuel gas) in the second introduction passage 43b.
The system that forms the spiral vortex flow is referred to as swirl supply means.

The operation of the waste melting furnace 1 of the present application will be described below. The coke packed bed 2 is burned by the primary air as a preheated oxygen-containing gas blown from the temporary air blowing nozzle 6 located below the packed bed 1500 to 160.
It is kept at a high temperature of 0 ° C. On the other hand, powdery waste such as sludge is blown into the combustion space 4 from the waste supply nozzle 4a provided in the combustion space in a state of about 10% water content after drying.
While being dried, burned and melted, it is sent into the coke filling layer 2 and unburned components are also melted in the coke filling layer 2 to form slag, which is discharged from the outlet 3. Here, in order to smoothly perform the combustion melting, the combustion space temperature is 120
0 ° C or higher, coke packed bed temperature is 1400 to 1500 ° C
It is necessary to maintain the above, but in the waste melting furnace 1 of the present application, by providing the hanging wall 8, the powdery waste and the oxygen-containing gas blown into the combustion space 4 chamber are directed downward. A good operating condition can be obtained because, for example, it can be prevented from being blown into the coke filling layer 2 to prevent wall side blow-through due to a short pass. That is, the residence time in the combustion space 4 becomes sufficient, complete combustion of combustible components and temperature rise by combustion are achieved, the furnace can be maintained at a predetermined temperature, and stable operation can be performed. On the other hand, as in the prior art, when the hanging wall 8 is not provided, it is difficult to sufficiently combust the powdery dust in the combustion space, and thus sludge as waste is scattered as dust into the exhaust gas as it is.

Experimental data relating to the usefulness of the present invention will be described below with reference to FIG. FIG. 3 (A) schematically shows the temperature distribution in the furnace of the waste melting furnace 1 having the structure including the hanging wall 8, and the one shown in FIG. 3 (B) is a conventional one without the hanging wall. Type of waste melting furnace. The operation status of each is shown below. Operation status comparison Test results With hanging wall Without hanging wall Sludge injection amount kg / h 30 30 Coke amount kg / h 12 20 Dust scattering amount g / Nm ³ 2.2 6 Primary air amount Nm ³ / h 62 70 Combustion space Blow-in air Nm ³ / h 60 90 As is apparent from the above results, when the hanging wall 8 is provided, the temperature inside the furnace is increased and the temperature is made uniform, and coke required for treating the same sludge is obtained. A significant reduction in the amount is achieved, and the amount of dust scattering is also greatly reduced.

The structure and operation of the waste melting furnace of the present application are as described above, but in order to prevent dust blow-through at the peripheral wall of the powdery waste as much as possible and send it into the layer,
In the case of forming the coke filling layer 2 in a general melting furnace,
It is also possible to control the flow in the furnace by changing the so-called coke layer structure, such as making the coke thick in the peripheral portion and thin in the central portion, but in the present application, this is because the thickness of the coke packed layer is thin. Therefore, it cannot be adopted. Furthermore, if the blowing speed into the combustion space is increased in order to send the powdery waste to the center side of the furnace, fluidization of the packed bed will occur for the same reason.
This measure cannot be adopted either. Therefore, in the present application, the hanging wall 8 is provided between the combustion space 4 and the coke packed layer 2, and the air and the powdery waste blown into the combustion space 4 short pass to the freeboard 5 immediately from the wall edge. By preventing blow-through, the above remarkable effects could be obtained.

[Other Embodiments] In the above embodiments, the hanging wall has a triangular shape that projects downward in a vertical sectional view, but this is a mere downwardly extending rectangular wall surface in vertical sectional view. May be In short, the gas guided from the combustion space 4 into the coke packed bed 2 moves directly to the side of the coke packed bed 2 and is prevented from being burnt and discharged through the packed bed. Any configuration may be used as long as it is provided. Further, as shown in the embodiment, the hanging wall 8 is not limited to a refractory having the inside filled, but may have a hollow structure, and this portion may have a water cooling structure, a boiler structure, or the like.

Further, although an example using coke was shown in the embodiment, any carbon-based combustible substance may be used.

In addition to sludge, municipal solid waste, various industrial wastes, and intermediate processed products obtained by dewatering, drying, incinerating, crushing, and the like of sludge, as the object to be treated, are powdered in a combustion space. Anything that can be blown into It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of a waste melting furnace.

FIG. 2 is a cross-sectional view of the waste melting furnace in the combustion space position.

FIG. 3 is a diagram showing a comparison result of furnace temperatures.

[Explanation of symbols]

 1 Waste Melting Furnace 2 Packed Bed 4 Combustion Space 8 Hanging Wall 42 Introduction Site 43a First Introduction Path 43b Second Introduction Path F Swirling Flow

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Muneharu Ichikawa 1-2-4 Nakamichi, Higashinari-ku, Osaka City, Osaka Prefecture (72) Inventor Shin Shimizu 2-chome, Otemachi 2-chome, Chiyoda-ku, Tokyo No. 1 Ishi Kawashima Harima Heavy Industries Co., Ltd. (72) Inventor Tetsuo Horie 22-1 Otemachi 2-chome, Chiyoda-ku, Tokyo Ishi Kawashima Harima Heavy Industries Co., Ltd. (72) Inventor Harunobu Sakabe Otemachi, Chiyoda-ku, Tokyo 2-2-1 Ishi Kawashima Harima Heavy Industries Co., Ltd.

Claims (5)

[Claims] 1. A filling layer (2) formed of a carbon-based combustible material, the filling layer (2) being provided at a position lower than an upper surface of the filling layer (2) in a transverse direction outer peripheral portion of the filling layer (2). An annular combustion space (4) communicating with the bed (2) is provided, and the waste material is blown into the combustion space (4) in a powder form, and the waste material is provided in the combustion space (4) and the packed bed (2). Is a waste melting furnace that burns fuel and transforms it into molten slag, at the boundary position between the combustion space (4) and the packed bed (2), a drooping wall protruding downward from the upper side of the combustion space (4). Waste melting furnace with (8). 2. A filling layer (2) formed of a carbon-based combustible material, the filling layer (2) being provided at a position lower than an upper surface of the filling layer (2) in an outer peripheral portion in a transverse direction of the filling layer (2). An annular combustion space (4) communicating with the bed (2) is provided, and the waste material is blown into the combustion space (4) in a powder form, and the waste material is provided in the combustion space (4) and the packed bed (2). A waste melting furnace that burns gas and melts into slag, and the flow direction of the combustion gas advancing from the combustion space (4) to the packed bed (2) is set obliquely downward. . 3. A plurality of introduction sites (4) dispersed in the circumferential direction.
A supply means for supplying the waste in a gas-carrying state from 2) to the combustion space (4) is provided in a peripheral portion of the combustion space (4), and a supply direction of the waste by the supply means is the above-mentioned. The waste melting furnace according to claim 1 or 2, wherein the waste melting furnace is set so as to form a swirl flow (F) in the annular combustion space (4). 4. The supply means comprises a first introducing passage (43a) for guiding the waste to the introducing portion (42), and is formed in a peripheral portion of the first introducing passage (43a) and contains oxygen. A swirl provided with a second introduction path (43b) for guiding the gas to the vicinity of the introduction part (42), and supplying the oxygen-containing gas as a spiral swirl flow around the waste at the introduction part (42). The waste melting furnace according to claim 3, further comprising a supply means. 5. The method for supplying the waste to the waste melting furnace according to claim 3, wherein the supply means is provided in the circumferential direction of the combustion space (4) at the plurality of introduction portions (42). A method of supplying waste, in which the supply of waste and the stop of supply of waste are sequentially performed to accelerate or suppress the swirling of the swirling flow (F) formed in the combustion space (4).