JPH0752003B2 - Ash melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention transfers incineration residues (incineration ash) of solid waste such as municipal solid waste and industrial waste onto a fire bed formed in a passage of a furnace body. The present invention also relates to an ash melting furnace that burns unburned carbon in the incinerated ash to perform melting processing.

[Prior Art] Conventionally, while transferring incinerated ash discharged from an incinerator onto a fire bed formed in a passage of a furnace body, air is supplied to the incinerated ash to burn unburned carbon in the incinerated ash. There is known an ash melting furnace for melting and treating incineration ash by using the heat generated by combustion as a heat source for melting.

[Problems to be Solved by the Invention] However, in the conventional ash melting furnace, although the combustion air is supplied, the passage of the furnace body is configured as a monotonous downward sloping form, so that the combustion gas ( The high temperature part of the flame could not be concentrated in the incineration ash layer, and the sensible heat of the flame could not be fully utilized.

The purpose of the present invention is to make full use of the sensible heat of a flame for combustion and
An object is to provide an ash melting furnace with accelerated melting.

[Means for Solving the Problems] In the present invention, an air nozzle is provided in a fire bed formed in a passage of a furnace body, and while combustion ash is transferred onto the fire bed, unburned in the combustion ash. In an ash melting furnace in which carbon is burned with air from an air nozzle to perform melting treatment, a weir hanging from above is provided in the middle of the passage of the furnace body, and the narrowing portion of the passage formed by this weir is used for combustion gas velocity. As a combustion zone to increase the incineration ash, a incineration ash filling zone is formed on the front side of the squeezing section and a freeboard larger than the squeezing section is formed at the rear of the squeezing section, Is formed in a V-shaped cross section so that the molten metal is collected in the center and flows down, and a large pusher for transferring combustion ash to the filling zone and a small pusher for forming a runner in the fire bed are provided.

[Operation] Air is supplied from an air nozzle provided in the fire bed formed in the passage of the furnace body to burn unburned carbon in the incineration ash, and a constriction is provided in the passage of the furnace body. By forming a combustion zone below it, an incineration ash filling zone on its front side, and a freeboard on its rear side, the flow of combustion gas through the combustion zone becomes faster and its heat density becomes higher. That is, in the combustion zone, the high temperature parts of the flame and the combustion gas are concentrated in the incineration ash layer to increase the thermal efficiency, and the combustion and melting of the incineration ash are promoted in the freeboard. In addition, the V-shaped cross section of the fire bed is provided with a large pusher that transfers combustion ash in the filling zone and a small pusher that forms a runner in the fire bed, so that the molten metal can be efficiently collected and flowed on the fire bed. Is possible.

EXAMPLES Examples of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an ash melting furnace, which is connected to the end of a mechanical incinerator (a stoker type furnace, a rotary kiln type, etc.) for incinerating solid waste such as municipal solid waste, and is incinerated. The incineration residue (incineration ash) incineration ash 20 containing unburned carbon discharged from the furnace is burned while being transferred to the fire bed, and the heat causes the incineration ash 20 to become molten slag (molten metal) 21.

The ash melting furnace 1 includes a furnace body 2 covered with a refractory heat insulating material,
Inside the furnace body, a passage 3 that is inclined downward is formed. A hopper 2a serving as an inlet for receiving the incineration ash 20 from the incinerator is formed in the upper portion of the furnace body 2, and the hopper communicates with the upstream upper portion 3a of the passage 3. Also, the furnace body 2
Is connected to the slag discharge passage 16 and leads to the slag cooling water tank. The combustion exhaust gas is sucked and discharged from the flue 17 by a blower (not shown) in the same direction as the molten metal 21 flows.

The passage 3 of the furnace body 2 is divided into three regions by a weir 4 provided in the middle of the passage 3 so as to hang down from the upper wall. That is, incineration ash
The incineration ash filling zone 5 located on the front side of the weir 4 when viewed in the transport direction of 20, the combustion zone 6 that is a passage portion narrowed by the weir 4, and the passage portion that is enlarged immediately after the weir 4. Free board 7. The reason for providing the weir 4 in the middle of the passage 3 is that when burning the incineration ash in the filling zone 5, the passage of the combustion gas (flame) is narrowed to increase the combustion gas velocity, which causes This is because the heat density (heat generation load) is increased to promote the melting of the incineration ash 20 only by the self-combustion heat. The existence of the filling zone 5 and the area of the freeboard 7 is an effective means for concentrating the high temperature portion of the flame or combustion gas in the incineration ash layer and promoting combustion melting.

In this embodiment, the center of the narrowed portion (combustion zone 6) of the passage 3 formed by the weir 4 is 400 to 400 mm from the upper part of the fire bed with respect to the length of the fire bed formed by the fire plate 8 of 1800 mm. 800 mm
Is provided so that the height of the narrowed portion from the fire plate 5 to the lower end of the weir 4 is 100 to 400 mm. It is preferable that the size of the freeboard 7 is relatively large for a height that is at least twice the height of the narrowed portion, and that the upper wall is flat. This is because if the height of the freeboard 7 is not sufficient or if there are obstacle protrusions or the like on the upper wall of the freeboard 7, the flow velocity of the flame decreases and unmelted ash increases.

In the passage 3 of the furnace body 2, a plurality of fire bed plates 8 made of ceramics such as silicon carbide are arranged stepwise to form an inclined fire bed. A high temperature electric heater 9 made of a rod-shaped silicon carbide heating element is integrally incorporated in each of the fire floor plates 8. Ten
Is an air nozzle (air diffuser) for ejecting high temperature combustion air sent from both sides of the passage 3.
Are arranged within the interval generated in the overlapping portion between the adjacent fire floor plates 8.

In FIG. 2 and FIG. 3, each fire floor plate 8 has a brim portion 81 for preventing the molten metal from wrapping around, and an insulating material having a heater insertion hole 84 formed in the lower portion of the fire floor plate body 80. A heater protector 83 composed of is integrally provided. 85 indicates a hole for the thermocouple.

The upper surface 82 of each fire plate 8 is V for collecting and flowing down the molten metal.
It is formed in a letter shape. Specifically, the V-shaped upper surface 82 of the firebed plate has an inclined guide surface 82a that collects the molten metal generated from the incineration ash 20 that is melted while being transported along the inclined guiding surface 82a, and the collected molten metal. It consists of a valley portion 82a that causes the incinerated ash 20 to flow down in the transfer direction.

Returning to FIG. 1, in each fire bed 8 having the above-mentioned configuration, the brim portion 81 is located on the downstream side in the transport direction of the incineration ash 20, and the brim portion 81 of the upper fire bed 8 is adjacent to the lower side. They are superposed on the fire plate 8 and arranged so as to form a stepwise fire plate. Further, these fire floor plates 8 are arranged so that, when a stepwise fire floor is formed, the envelope connecting the upper corners of the flanges 81, that is, the upper surface of the hearth, has a constant inclination angle. On the other hand, the electric heater 9
It is housed in the insertion hole 84 of the heater protector 83 and integrated with the fire bed plate 8, thereby protecting the electric heater 9 from the inflow of molten metal and efficiently heating the fire bed plate 8 from the inside.

The first role of the electric heater 9 is to heat the fire plate 8 from the inside, and to give ignition heat from the lower surface to the incineration ash 20 stacked in the combustion zone 6 by radiant heat from the surface of the fire plate 8. It is in. This means that in combination with the high temperature air supplied to the inner lower surface of the incineration ash by the air nozzle 10, combustion and melting are performed from the inner lower surface of the incineration ash layer in the combustion zone 6, and therefore the highest temperature is required. The heat loss is reduced because the part to be covered is covered with an incinerated ash layer and kept warm. The other role of the electric heater 9 is the incineration ash 20 in the filling zone, that is, the incineration ash to be burned next.
The purpose is to preheat 20 to a high temperature to promote combustion melting and prevent molten slag, that is, molten metal 21 in the melting zone of the freeboard 7 from sticking in the furnace body 2.

Therefore, the electric heaters 9 are divided into groups to control the temperature of the fire floor plate 8 in several sections. In this example, the pre-tropical zone of the filling zone 5 is 900 ° C., the combustion zone of the combustion zone 6 which is the narrowed portion of the passage is 1100 ° C., and the melting zone of the freeboard 7 is 1300.
The temperature of the discharge port (gate) 8d is controlled at 1350 ° C.
By separately controlling the preheating zone, the combustion zone, the melting zone, and the sprue section in this way, it is possible to appropriately manage the temperature of combustion and melting and save the heating power. Also, the amount of combustion air blown from the electric nozzle 10 is 20% in the pre-tropical zone and 60 in the combustion zone by changing the supply pressure from the air supply pipe 11.
%, So that the combustion ash 20 is efficiently burned and melted.

On the other hand, on the upstream end wall of the furnace body 2, a large pusher 12 that mainly stirs and transfers the incineration ash 20 in the filling zone 5 and the combustion zone 6, and an incineration ash 20 that is mainly in the melting zone of the freeboard 7. An elongated small pusher 13 for making a hole to be a runner is provided therein. Small pusher 13
Is housed in the large pusher 12 together with the hydraulic cylinder, and its tapered tip portion 13a is arranged so as to be inserted / pulled out just above the center of the fire bed 8. The reason why the small pusher 13 is floated from the fire plate 8 and is not inserted and slid on the fire plate 8 is that a permanent layer of the molten metal is left on the fire plate 8 to form a protective film for the fire plate 8. However, if the small pushers 13 are too far away from the fire plate 8, the holes formed between the fire plate 8 and the incinerated ash will not function as runners, so a proper gap must be provided. In the case of the embodiment shown in FIG. 1, it is preferable that this gap be 30 to 50 mm. The diameter of the small pusher 13 at this time is 50 ~
Although it was set to about 100 mm, it is preferable to be thin to secure a runner.

The large pusher 12 and the small pusher 13 are provided with an encoder 14 for the purpose of detecting the protruding speed and the current position. The output pulse from the encoder 14 is input to a pressure controller 15 having a built-in computer (CPU), and the controller 15 controls the large and small pushers 12 and 13 in cooperation with each other.

Next, the operation of the ash melting furnace having the above configuration will be described.

Solid waste 7 such as municipal waste is supplied to an incinerator (not shown) where it is ignited by an auxiliary burner and then self-combusted by combustion air, and the incinerated ash 20 is introduced into the ash melting furnace 2 from the hopper 2a. To be done. At that time, unburned carbon remains in the incinerated ash 20, but the amount is particularly preferably 7 to 25% by weight.
Combustion in the incinerator is controlled so that it remains in the range of 10 to 20% by weight. Specifically, the amount of refuse input, the amount of combustion air, the feed rate of the stoker in the stoker type furnace, and the rotation speed in the rotary kiln type furnace are adjusted to allow the waste to remain.

The incinerated ash 20 containing unburned carbon passes through the hopper portion 2a and is stacked on the fire plate 8 in the melting furnace 2, and about 900 in the filling zone 5.
After being preheated to ℃, it moves to the combustion zone 6. Combustion zone 6
Since the temperature of the fire plate 8 is normally controlled to 1100 ° C., the unburned carbon on the inner bottom surface of the incineration ash 20 is first generated by the high temperature combustion air blown out from the air nozzle 10 located on the inner bottom surface of the incineration ash 20. Is ignited, and the incinerated ash 20 self-combusts from inside. The flame or combustion gas generated during this combustion escapes from the combustion zone 6 to the freeboard 7, but since the combustion zone 6 is narrowed by the weir 4, the combustion gas velocity in the combustion zone 6 becomes high and its heat density is Get higher That is, this high-density self-combustion heat is concentrated on the incineration ash 20, and the incineration ash 20 is heated and melted with high thermal efficiency to form a molten slag, that is, a molten metal 21.

Since at least 1250 ° C. is required for this molten metal 21 to flow over the fire plate 8, the temperature of the fire plate 8 is, as already mentioned,
It is controlled at 1300 ° C in the melting zone of the freeboard 7 and at slightly higher 1350 ° C at the sprue part (the most advanced part of the fire bed part 8) 8d to prevent the molten metal from sticking in the furnace.

The molten metal 21 on each fire plate 8 advances on the V-shaped inclined guide surface 82a toward the valley 82a, and is collected in the valley 82a, and then the valley 82a.
It becomes a single stream along the line and flows to the sprue part 8d. The melt flow is concentrated at one location on the fire plate 8 and does not spread over the fire plate 8, so the flow of the melt is good and does not show the signs of sticking as with a flat fire plate. The molten metal 21 thus flowing over the fire plate 8 and exiting from the spout portion 8d falls through the slag discharge passage 16 into a slag cooling water tank (not shown), where it is cooled and solidified.

The large pusher 12 and the small pusher 13 stir and transfer the incineration ash 20 by the linked operation, thus contributing to the combustion and melting control of the incineration ash 20 and preventing the incineration ash 20 from crosslinking and forcibly discharging the unsuitable materials. I do. At this time, if the delivered large pusher 12 stops before reaching the specified stroke length, it is considered that a clinker (fixed slag) has occurred in the passage 3. Further, when the delivery speed of the large pusher 12 is slower than the specified speed, it is considered that the slag sticking symptom, that is, the clinker, is being generated in the passage 3.

Therefore, when sending out the large pusher 12, the controller 15 monitors whether the number of output pulses per unit time (sending speed) generated from the encoder 13 falls below a predetermined value, and if it falls below the predetermined value, , Judge that there is a sign of slag sticking. Further, when the number of output pulses generated per unit time from the encoder 13 is zero, that is, when the large pusher 12 stops, the output pulse generated from the encoder 13 until the large pusher 12 stops from its original position. The integrated value of the numbers is compared with a predetermined set value, and if the integrated value has not reached the set value yet, it is determined that the operation has stopped due to the occurrence of a clinker. And the controller 15
When such a clinker is detected, the electric heater 9 in the clinker generation part is intensified and the fixed slag is removed and discharged by the combination operation of the large pusher 12 and the small pusher 13.

On the other hand, the molten metal 21 is often difficult to flow out due to the unmelted ash. When the melt stays, it causes sticking on the fire slab 8 and causes an accompanying flow of unmelted ash, and when mixed with unmelted ash, it increases ventilation resistance to the incinerated ash layer and burns the incinerated ash. Inhibit. Therefore, particularly in the melting zone of the freeboard 7, the controller 15 activates the small pusher 13 to insert and remove the small pusher 13 right above the center of the fire plate 8. As a result, a hole is formed between the fire plate 8 and the incineration ash 20 as a runner, and the runner improves the flow of the molten metal.

In the above-mentioned embodiment, the ash melting furnace in which the hearth is formed by the plurality of fire floor plates 8 has been described. However, the ash melting furnace using one flat fire floor plate, and further the heat of an oil burner or the like melts. Even in the ash melting furnace, by providing the weir 4 and increasing the combustion gas velocity in the combustion zone 6, the heat density there can be increased and the thermal efficiency can be increased.

EFFECTS OF THE INVENTION As described above, according to the present invention, air is supplied from an air nozzle provided in a fire bed formed in a passage of a furnace body to burn unburned carbon in incinerator ash, and By forming a constriction part in the middle of the passage of the body and forming a combustion zone below it, an incineration ash filling zone on the front side, and a freeboard on the rear side, the flow of combustion gas through the combustion zone becomes faster, Its heat density becomes high. In other words, in the combustion zone, the high temperature parts of the flame and combustion gas are concentrated in the incineration ash layer, the sensible heat of the flame is fully utilized, the thermal efficiency is increased, and the combustion and melting of the incineration ash is promoted in the freeboard. It

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the ash melting furnace of the present invention,
The figure is a front view of the fire bed, and FIG. 3 is a side view thereof. In the figure, 1 is an ash melting furnace, 2 is a furnace body, 3 is a passage, 4 is a weir, 5
Is a filling zone, 6 is a combustion zone, 7 is a freeboard, 8
Is a fire plate, 9 is an electric heater, 10 is an air nozzle, 12 is a large pusher, 13 is a small pusher, 14 is an encoder, 15 is a pusher controller, 20 is incineration ash, and 21 is molten metal.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Minoru Miyakoshi 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Tokyo 1st factory (72) Inventor Takehiko Motomura 2-chome, Toyosu, Koto-ku, Tokyo No. 1 Ishikawajima Harima Heavy Industries Co., Ltd. Tokyo No. 1 Factory (72) Inventor Masao Seki No. 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawajima Harima Heavy Industries Co., Ltd. Technical Research Institute (56) Reference JP-A-60- 33418 (JP, A) JP 54-154170 (JP, A) JP 55-24010 (JP, B2)

Claims (1)

[Claims] 1. An air nozzle is provided in a fire bed formed in a passage of a furnace body, and combustion ash is transferred onto the fire bed,
In an ash melting furnace in which unburned carbon in the combustion ash is burned with air from an air nozzle to perform melting treatment, a weir that is suspended from above is provided in the middle of the passage of the furnace body, and the passage formed by this weir The squeezing part of the slag is used as a combustion zone for increasing the combustion gas velocity, the incineration ash filling zone is located in front of the squeezing part facing the transfer direction of the incineration ash, and the squeezing part has a free zone larger than the squeezing part in the rear part. A board is formed, the fire bed is formed into a V-shaped cross section so that the molten metal is collected in the center and flows down, and a large pusher that transfers combustion ash to the filling zone and a small runner that forms a runner on the fire bed. Ash melting furnace characterized by having a pusher.