JPH07269820A - Waste melting furnace - Google Patents

Abstract

PURPOSE:To provide a waste melting furnace in which combustion of waste can be effectively executed in a small unevenness state by uniformly receiving radiation heat from a packed bed by a combustion space. CONSTITUTION:A waste melting furnace 1 comprises a packed bed 2 formed of carbon combustible substance C, and a combustion space 4 provided at a lateral outer periphery of the bed 2 at a lower position than an upper surface of the bed 2 to communicate with the bed 2, wherein waste H is sprayed in powder state to the space 4 to burn the waste H in the space 4 and the bed 2 and to melt to slag.,it, and a combustion space forming oblique inner peripheral wall 10 is formed along an oblique surface 2a of the bed 2 exposed with the space 4 at an angle of repose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a packing layer formed of a carbon-based combustible material (for example, coke), which is located at a position lower than the upper surface of the packing layer, in the outer circumferential portion of the packing layer, The present invention relates to a waste melting furnace that includes a combustion space communicating with a packed bed, blows waste in powder form into the combustion space, burns the waste in the combustion space and the packed bed, and converts the waste into molten slag.

[0002]

2. Description of the Related Art Conventionally, as a waste melting furnace of this type,
As shown in FIG. 4, a ceiling wall 20, a vertical wall 21 and an inclined wall 22 are continuously provided as an inner peripheral wall for forming the combustion space 4, the ceiling wall 20 is in a horizontal direction, the vertical wall 21 is in a vertical direction, Some of the inclined walls 22 are arranged such that the inner peripheral surfaces of the inclined walls 22 extend inward in the direction in which the lower ends thereof project inward of the packed bed 2,
The waste H blown into the combustion space 4 surrounded by the ceiling wall 20, the vertical wall 21, and the inclined wall 22 is burned and melted, and the inclined wall 22 surface in the packed bed 2 is discarded as a guide surface. The molten slag of the product H was made to flow down and be collected.

[0003]

The waste blown into the combustion space burns in a state of receiving radiant heat from the inclined surface of the packed bed exposed at the angle of repose in the combustion space. According to the conventional waste melting furnace described above, since the inner peripheral wall for forming the combustion space is not along the inclined surface of the packed bed, there is a risk that the degree of receiving the radiant heat varies greatly depending on the site of the combustion space. In burning the waste, it is difficult to effectively use the radiant heat from the packed bed, and there is a problem that variations in combustion are likely to occur.

Therefore, the object of the present invention is to solve the above problems, to receive the radiant heat from the packed bed evenly in the combustion space, and to carry out the combustion of waste effectively and with little variation. It is about to provide a waste melting furnace that can.

[0005]

A feature of the waste melting furnace of the present invention for achieving this object is that it comprises a packing layer formed of a carbon-based combustible substance, and the position is lower than the upper surface of the packing layer. At the outer peripheral portion of the packed bed in the transverse direction, a combustion space communicating with the packed bed is provided, and the waste is blown in powder form into the combustion space to burn the waste in the combustion space and the packed bed. In addition, in the waste melting furnace that melts into slag, an inclined inner peripheral wall for forming a combustion space is formed along the inclined surface of the packed bed exposed at the angle of repose in the combustion space.

Further, it is preferable that at least a lower end of the inclined inner peripheral wall is connected to an inner peripheral wall of which at least the lower end does not incline inward of the packed bed, and further, the combustion space is
It is preferable that the filling layer is formed in an annular shape along the circumferential direction.

A water cooling mechanism may be provided on the inner peripheral wall of the furnace, and pressure adjusting means may be provided for adjusting the pressure of the cooling water flow space of the water cooling mechanism.

[0008]

According to the characteristic structure of the waste melting furnace of the present invention, the inclined inner peripheral wall for forming the combustion space is formed along the inclined surface of the packed bed exposed at the angle of repose in the combustion space. The interval between the inclined surface of the packed bed and the inclined inner peripheral wall for forming the combustion space is constant or almost constant at any position, and the waste blown into the combustion space is separated from the inclined surface of the packed bed. It is possible to receive radiant heat under almost the same conditions. As a result, it becomes possible to cause the radiant heat to uniformly and effectively act on the waste, and to perform highly efficient waste combustion with little variation.

Further, if the inner peripheral wall of which at least the lower end does not incline toward the inner side of the packed bed is connected to the lower end portion of the inclined inner peripheral wall, molten slag of the waste combusted and melted in the combustion space is generated. , Respectively, it is possible to flow directly down the packed bed, for example, as compared with the conventional one that uses the inclined wall surface as the flow-down guide surface of the molten slag, the molten slag can be smoothly flowed down and melted. It is possible to prevent the slag from being absorbed by heat in the process of being guided by an inclined wall to flow down and solidifying, and to prevent the molten slag from flowing down as a whole, so that the molten slag flows down efficiently. Is possible.

Furthermore, if the combustion space is formed in an annular shape along the circumferential direction of the packed bed, it becomes possible to blow waste into a circular combustion space in a swirling state, and a large combustion space is formed. In addition, it is possible to secure combustion and to achieve highly efficient combustion by substantially uniform heating.

If a water cooling mechanism is provided on the inner peripheral wall of the furnace, it is possible to prevent the temperature of the inner peripheral wall of the furnace from rising too much, to suppress deterioration of the inner peripheral wall of the furnace, and to control the temperature of the inner furnace. It becomes possible to do. As an example of the control of the temperature inside the furnace by the water cooling mechanism, it is possible to carry out by increasing or decreasing the temperature of the cooling water and increasing or decreasing the flow rate. Further, if the pressure adjusting means for adjusting the pressure of the cooling water distribution space of the water cooling mechanism is provided, the pressure of the cooling water flowing in the cooling water distribution space can be adjusted, and the pressure adjustment is possible. By increasing the pressure of the cooling water by means, the temperature of the cooling water is increased, the heat removal amount of the furnace by the water cooling mechanism is reduced,
By performing the reverse operation to increase the heat removal amount and control the furnace temperature to a temperature suitable for waste combustion and molten slag formation, efficient waste combustion and molten slag formation are possible. Further, in this case, the amount of heat removal can be controlled without flowing a large amount of cooling water, as compared with the case of cooling only by controlling the flow rate of cooling water.

[0012]

Therefore, according to the waste melting furnace of the present invention, the radiant heat from the packed bed is made to act evenly on the waste in the combustion space, so that the combustion of the waste is effectively and unevenly distributed. It becomes possible to carry out the process in a small amount, and it becomes possible to improve the efficiency of burning waste and converting it into molten slag.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the parts indicated by the same reference numerals as those in the conventional example indicate the same or corresponding parts.

In this embodiment, combustion of waste sewage sludge
FIG. 1 shows a cross-sectional view of the main part of the waste melting furnace 1 for melting, which is for melting. As shown in the figure, this waste melting furnace 1 is provided with a roughly vertical cylindrical coke filling layer (an example of a filling layer) 2 formed by filling a block of coke C, which is an example of a carbon-based combustible substance. ,
The coke packed bed 2 is provided with a slag port 3 through which molten slag is smelted at a lower position thereof, and an annular combustion is formed at a position lower than an upper surface of the coke packed bed 2 in an outer peripheral portion in the transverse direction. A space 4 is provided, and a freeboard 5 is provided at an upper portion of the coke filling layer 2. 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.

The waste melting method of this embodiment is a slaked lime P1 (powder) which is an example of a powdery basicity adjusting agent, a powder coke C1 which is an example of a powdery carbonaceous combustible substance, and a waste. The sewage sludge is sent into the combustion space 4 together with the powdered waste H in the form of powder and burned in the combustion space 4 and the packed bed 2 to form molten slag.

The powdery waste H is obtained by dehydrating the sewage sludge discharged from the sewage treatment facility with a dehydrator to a water content of about 70%, and then drying it (for example, an indirectly heated disk using steam as a heat source). Which has been dried and powdered by a drier) before being blown into the combustion space 4 of the waste melting furnace 1 (for example, a dryer inlet or a storage hopper for storing waste after drying), It is mixed with the slaked lime P1 and the powder coke C1. The slaked lime P1 is used as powdered waste H
By mixing prior to combustion, the basicity of the mixture can be adjusted to 0.5-1.5, mutual melting point lowering can be achieved, and the fluidity of the molten slag can be improved. By fixing phosphorus contained in the powdery waste H to a substance having a high melting point (for example, calcium phosphate such as tricalcium phosphate), it is possible to prevent scattering in the combustion exhaust gas and accelerate desulfurization. It will be possible. Further, by mixing the powdery waste H with the powder coke C1 and burning the mixture, the combustibility of the powdery waste H is prevented from lowering, and the coke filling layer 2 is made into a reducing atmosphere to be reduced from the molten slag. It is possible to separate the metal and improve the quality of the recovered slag.

Next, the combustion space 4 will be described. A waste supply nozzle 4a for supplying a mixture of the powdered waste H, slaked lime P1, and powder coke C1 to the combustion space 4 by carrier air, oxygen. An oxygen-containing gas supply nozzle 4b for blowing the contained gas and an auxiliary fuel blowing nozzle 4c for blowing the auxiliary fuel are provided (see FIG. 2).
Therefore, in the combustion space 4, the combustion of the fuel is occurring, and the powdery waste H sent into the combustion space 4 is dried and burned, and the generated combustion gas is generated together with the unburned substances. It is sent into the coke packed bed 2 while drawing a trajectory that swirls around the coke packed bed 2.

Further, at the boundary position between the combustion space 4 and the coke packed layer 2, the protrusion overhangs from the upper side of the combustion space 4,
On the combustion space 4 side, there is provided a hanging wall 8 having a descending guide surface 8a which is an inclined surface located upward as it is separated from the coke filling layer 2 (see FIG. 1). The hanging wall 8
Is formed by applying a refractory material to the water cooling jacket 12. By providing this hanging wall 8, the combustion gas in the combustion space 4 can be compared with the case where this hanging wall 8 is not provided.
The advection into the coke packed bed 2 is delayed (the swirl amount increases), and the flow direction of the combustion gas into the coke packed bed 2 is set to be obliquely downward.

Further, an inclined inner peripheral wall 10 for forming a combustion space is formed on the outer peripheral portion of the coke filling layer 2 along the inclined surface 2a of the coke filling layer 2 exposed to the combustion space 4 at an angle of repose. At the same time, the lower end of the inclined inner peripheral wall 10 is provided with an inner peripheral wall 11 extending directly downward.

A water cooling jacket 12 which is an example of a water cooling mechanism is provided on each of the inclined inner peripheral wall 10 and the inner peripheral wall 11. The water cooling jacket 12 has a cooling water distribution space 13 formed therein, and the cooling water from the cooling water supply device 14 connected in communication is circulated in the cooling water distribution space 13 and discharged from the drainage section. Heat exchange,
The hanging wall 8, the inclined inner peripheral wall 10, and the inner peripheral wall 11 are cooled so that the temperature inside the furnace can be adjusted. In addition, in the supply flow path 15 and the discharge flow path 16 that are connected to the cooling water flow space 13, the hanging wall 8 and the inclined inner peripheral wall 10 are provided.
A plurality of valves B that can individually adjust the flow rate of cooling water flowing through the inner peripheral wall 11 are provided. The discharge passage 16 is provided with a pressure adjusting means T capable of adjusting the pressure of the cooling water circulation space 13. In this embodiment, the pressure adjusting means T is a PIC (Pressure Indicator).
ng Controller). The control of the temperature inside the furnace using the water cooling jacket 12 can be performed by increasing / decreasing the flow rate and increasing / decreasing the temperature of the cooling water. The operation for raising and lowering the temperature of the cooling water can be performed by adjusting the temperature of the cooling water before the supply, but in the present embodiment, the cooling water is circulated in the cooling water circulation space 13. It is also possible to carry out by operating the pressure of the cooling water up and down by the pressure adjusting means T. Specifically, the cooling water temperature is raised by increasing the pressure of the cooling water to reduce the heat removal amount of the furnace by the water cooling jacket 12, or the opposite operation is performed to increase the heat removal amount. Control the furnace temperature. As a result, the amount of heat removed can be controlled without supplying a large amount of cooling water to the cooling water distribution space 13, and the furnace temperature can be efficiently controlled to a temperature suitable for waste combustion and molten slag formation. It becomes possible. Table 1 shows the relationship between the temperature of the cooling water having a temperature of 40 ° C. under normal pressure when the pressure is increased and the heat removal amount in that state.

[0021]

[Table 1]

However, the heat removal amount Q is obtained by the following equation. Q = K · (t ₁ −t ₂ ) · S Q: Heat removal amount (kcal / hr.) K: Overall heat transfer coefficient (kcal / m ² · hr · ° C) t ₁ : Temperature in furnace (° C) (t) ₁ = 1200 ° C.) t ₂ : Cooling water temperature (° C.) S: Heat transfer area (m ² )

On the other hand, at the upper portion of the freeboard 5, there is provided a supply section 9 for supplying the supply K to the coke filling layer 2. The feed K is composed of a lump containing a combustible material that can be melted and slagged in the coke packed layer 2, and in the present embodiment, a lump waste K1 obtained by lumping sludge, which is a waste, and The lumpy basicity adjusting agent K2 for adjusting the basicity of the molten slag in the coke packed layer 2 is used as the feed K. In addition, it is also possible to use the slag recovered from the coke packed bed 2 as sand or lump slag, or coke as the feed K. Examples of the lumpy basicity adjusting agent K2 include limestone and crushed stone, and when the lumpy basicity adjusting agent K2 is mixed with the lumped waste K1 and the lumped slag, it has a function of enabling melting at a low melting point.

The operation of the waste melting furnace 1 of the present application will be described below. The coke packed bed 2 is maintained at a high temperature by being burned by the preheated primary air as the oxygen-containing gas blown from the temporary air blowing nozzle 6 located below the packed bed. Further, the powdery waste H is blown into the combustion space 4 from the waste supply nozzle 4a provided in the combustion space 4 in a state of being mixed with the slaked lime P1 and the powder coke C1, and the radiant heat from the coke filling layer 2 is discharged. While being dried, burned, and melted while being received, it is sent into the coke filling layer 2, and unburned components are also melted into slag in the coke filling layer 2, flow down, and are discharged from the outlet 3. On the other hand, the feed K is supplied from the supply unit 9 to the upper portion of the coke filling layer 2 to be combusted and melted, and is melted into slag in the coke filling layer 2 to flow down to flow from the combustion space 4. The molten slag is discharged from the outlet 3. Then, through these steps of burning and melting slag, the temperature control of the cooling water flowing in the cooling water distribution space 13 by the water cooling jacket 12, the cooling water supply device 14, and the pressure adjusting means T is carried out, A furnace temperature environment suitable for melting waste is maintained.

[Other Embodiment] Another embodiment will be described below. <1> The carbon-based combustible substance is not limited to the coke described in the above embodiment, and any other carbon-based combustible substance may be used.

<2> The waste is not limited to the sewage sludge described in the above embodiment, but can be obtained by, for example, municipal solid waste, various industrial wastes, and dehydration drying, incineration, crushing, etc. thereof. It may be an intermediate processed product or the like, and any product can be used as long as it is powdery and can be blown into the combustion space.

<3> The inner peripheral wall 11 is not limited to the one extending in the direct downward direction at the lower end portion of the inclined inner peripheral wall 10 described in the previous embodiment, and for example, as shown in FIG. In addition, the lower end side may be formed on the inclined wall located on the outer side of the coke packed layer 2, and by doing so, the molten slag flowing down to the combustion space 4 near the inner peripheral wall 11 may be formed. It becomes easier to prevent caking. Therefore, it may extend in the same plane as the inclined inner peripheral wall 10.

<4> The water cooling mechanism is not limited to the water cooling jacket described above, and may be an internal type that is formed by being incorporated into the hanging wall 8, the inclined inner peripheral wall 10 and the inner peripheral wall 11. Good. Also, the hanging wall 8 and the inclined inner peripheral wall 10
It is not limited to being separately provided on the inner peripheral wall 11, and it may be provided on any one of them, and the water cooling jacket and the interior type may be selectively used or may be configured by combining both. It may be.

<5> The pressure adjustment of the cooling water circulation space 13 using the pressure adjusting means may be automatically controlled by PID control. Further, the pressure adjusting means is not limited to the above-mentioned PIC, but may be constituted by other means.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a waste melting furnace according to an embodiment.

FIG. 2 is a top view explanatory diagram showing a combustion space.

FIG. 3 is a conceptual diagram showing a waste melting furnace of another embodiment.

FIG. 4 is a conceptual diagram showing a conventional waste melting furnace.

[Explanation of symbols]

 2 Packed bed 2a Inclined surface 4 Combustion space 10 Inclined inner peripheral wall 11 Inner peripheral wall 12 Water cooling mechanism 13 Cooling water distribution space C Carbon-based combustible substance H (powdered) waste T Pressure adjusting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Nishimura 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd. (72) Inventor, Muneharu Ichikawa 4-chome, Hirano-cho, Chuo-ku, Osaka 1-2 In Osaka Gas Co., Ltd. (72) Inventor Naoto Yoshinari 2-2-1 Otemachi, Chiyoda-ku, Tokyo Ishi Kawashima Harima Heavy Industries Co., Ltd. (72) Inventor Harunobu Sakabe Two Otemachi, Chiyoda-ku, Tokyo 2-2-1 Ishi Kawashima Harima Heavy Industries Co., Ltd. (72) Inventor Toshiyuki Suzuki 2-2-1 Otemachi, Chiyoda-ku, Tokyo Ishi Kawashima Harima Heavy Industries Co., Ltd.

Claims (4)

[Claims] 1. A filling layer (2) made of a carbon-based combustible substance (C) is provided, and the filling layer (2) is provided at a position lower than the upper surface of the filling layer (2) in the outer peripheral portion in the transverse direction. A combustion space (4) communicating with the packed bed (2) is provided, and the waste (H) is blown into the combustion space (4) in the form of powder to obtain the combustion space (4) and the packed bed (2). In the waste melting furnace for burning the waste (H) and converting it into molten slag in the step (1), along the inclined surface (2a) of the packed bed (2) exposed at the angle of repose in the combustion space (4). And a waste melting furnace in which an inclined inner peripheral wall (10) for forming a combustion space is formed. 2. The waste according to claim 1, wherein an inner peripheral wall (11), at least the lower end side of which is not inclined inward of the packed bed (2), is connected to a lower end portion of the inclined inner peripheral wall (10). Thing melting furnace. 3. The waste melting furnace according to claim 1, wherein the combustion space (4) is formed in an annular shape along the circumferential direction of the packed bed (2). 4. A water cooling mechanism (12) is provided on the inner peripheral wall of the furnace, and a pressure adjusting means (T) is provided for adjusting the pressure of the cooling water flow space (13) of the water cooling mechanism (12). ~
3. The waste melting furnace according to any one of 3 above.