JPH0743102B2 - Melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention melts and solidifies combustible components contained in waste such as dried sewage sludge, incineration residue, and municipal waste incineration residue. Relating to a melting furnace.

[Conventional technology]

In recent years, the amount of waste such as sewage sludge and municipal waste incineration residue has been increasing year by year, and securing landfill sites has become increasingly difficult. In addition, the risk of contamination due to the elution of harmful heavy metals such as mercury, copper, Cr, and Cd contained in waste is taken up as a long-term problem. Under these circumstances, further volume reduction and detoxification have become important issues in waste treatment.

Various new techniques have been studied as a waste treatment method, and a swirling flow type melting furnace has been proposed as one of them (see, for example, Japanese Patent Application No. 1-66541). As shown in FIG. 8, the swirl flow type melting furnace 1 is configured such that a melted material supply port 13 and a combustion air blowing port 2 which are open in a tangential direction of a cylindrical portion are provided at an upper portion and the cylindrical portion is made small by an inclined surface. The first stage swirling melting chamber 4 provided with the narrowed portion 12 at the lower part, the inlet portion 18 communicating with the first portion swirling melting chamber 4 inclined with respect to the first stage swirling melting chamber 4, and the tangential direction of the cylindrical portion. The second-stage swirl melting chamber 5 provided with the combustion air blowing port 3 open to the upper part and the throttle part 16 in which the cylindrical part is made small by the inclined surface at the lower slag outlet 15 and each swirling melting chamber 4 It is composed of auxiliary combustion burners 6 and 7, which are respectively installed on the upper portions of the and 5 ,.

In such a swirl type melting furnace 1, for example, when treating a dried product of sewage sludge, first, an auxiliary combustion burner 6,
Combustion gas such as heavy oil is blown into the first-stage swirl melting chamber 4 and the second-stage swirl melting chamber 5 by 7 to raise the temperature of each swirl melting chamber 4, 5. Due to this temperature rise, the temperature of the swirling and melting chambers 4 and 5 rises to a temperature suitable for melting the ash content of sludge and allowing the melt to flow in the furnace. After that, the dried sewage sludge is swirled in the swirling and melting chambers 4 and 5 from the melted material supply port 13 provided in the upper part of the furnace body.
Inject tangentially inside. Combustion gas is blown tangentially from the auxiliary combustion burners 6 and 7 into the cylindrical swirling melting chambers 4 and 5, and air is blown tangentially from the combustion air blowing port 2. A strong swirling airflow is formed in 4,5, so that the injected sewage sludge dried product swirls along the swirling airflow.

Due to this swirling flow, centrifugal force acts on the dried particles,
Separation of fine and coarse particles occurs. Fine particles are burned in a short time together with volatile matter in a short time, while coarse particles are captured by the molten slag surface formed on the inner wall surface of the furnace and efficiently burned, whereby a high furnace load can be realized. Therefore,
The combustion heat of the sludge makes it possible to maintain the inside of the furnace at a high temperature, and at the same time as the combustion, melting of the ash is achieved.

The melt is collected on the wall surface of the furnace, flows down while forming a slag surface in the furnace, and is taken out from the slag outlet 15 in the lower part of the furnace.

In this way, the swirling-flow type melting furnace can effectively use the heat generated by the combustible components in the waste for melting the ash, thus enabling a significant reduction in auxiliary fuel and melting aid, and is economically superior. The device can deal with various problems of waste disposal.

[Problems to be Solved by the Invention]

However, in the conventional swirl flow type melting furnace, the temperature of the slag outlet may be equal to or lower than the melting temperature of the slag depending on the properties of the material to be melted and the operating conditions. In that case, there was a risk that the molten slag flowing down was sequentially solidified at the slag outlet, and finally the outlet was blocked.

In particular, immediately after stopping the operation in the melting furnace, the molten slag may still remain in the melting furnace, and in such a state, the molten slag is solidified at the slag outlet, and the slag outlet is May be blocked. When the slag outflow becomes difficult due to the blockage of the slag outlet, the swirl flow type melting furnace cannot be operated. In addition, since the accumulated slag is solidified together with the furnace material that constitutes the melting furnace, removal work is not easy and may damage the furnace material.In some cases, the slag outlet must be destroyed. If the solidified slag cannot be removed, repair work is required. As described above, the trouble of blocking the slag outlet due to the slag causes a very serious problem.

The problem of blockage at the slag outlet may occur not only in the swirl-type melting furnace described above but also in any type of melting furnace as long as it is a melting furnace. Is.

An object of the present invention is to solve the above problems in a melting furnace, a heat storage body is installed in an exhaust passage that discharges exhaust gas and molten slag, and the heat storage energy is used to melt the molten slag near the slag outlet. Is kept higher than the melting temperature of the slag, and the molten slag is prevented from solidifying and depositing at the slag outlet, blocking the outlet, and stably melting and separating the material to be melted. Is to provide a melting furnace capable of.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention relates to a melting chamber for melting a material to be melted, a molten material supply port for supplying the material to be melted to the melting chamber, a slag outlet which is an outlet of the melting chamber, and a slag outlet communicating with the slag outlet. An exhaust passage comprising an exhaust gas passage for exhausting exhaust gas and a slag exhaust outlet for discharging slag, and the slag for holding thermal energy received from the molten slag and the exhaust gas with respect to the slag outlet and the slag exhaust outlet The present invention relates to a melting furnace having a heat storage body arranged in the discharge passage near the outlet of the outflow port.

[Action]

Since the melting furnace according to the present invention is configured as described above, it operates as follows.

In this melting furnace, the heat storage body is arranged in the vicinity of the outlet of the slag outlet in the discharge passage that discharges the exhaust gas and the slag that communicate with the slag outlet that is the outlet of the melting chamber. Heat is received from the heat storage body, and the heat storage body suppresses heat radiation to the outside at the slag outlet, the heat storage body serves as a heat radiation medium to store heat energy, and heat storage energy can be applied to the molten slag at the slag outlet portion. Even if the temperature of the slag outlet decreases, it is possible to prevent the molten slag from solidifying at the slag outlet, and to prevent the gas temperature from decreasing.

In this way, since the heating of the molten slag is promoted by the heat storage body, it is avoided that the molten slag is cooled to the melting temperature of the slag or less at the slag outlet, and as a result, the molten slag is solidified. Therefore, the solidified slag eliminates the risk of blocking the slag outlet.

Further, in this melting furnace, the heat storage body itself receives radiant heat from the molten slag during operation of the melting furnace to accumulate thermal energy, and is made of a heat-resistant material having high specific heat. Although the heat storage body cannot heat the slag outlet part like a heating plate, for example, a situation in which the temperature inside the melting furnace sharply decreases due to changes in the properties of the material to be melted and operating conditions has occurred. Even in such a case, the temperature of the slag outlet can be kept high by the radiant heat from the heat storage plate, and the clogging of the slag outlet due to the slag can be prevented.

Further, even if the molten slag still remains in the melting furnace immediately after the operation of the melting furnace is stopped, the temperature of the slag outlet part is kept at a high temperature for a while due to the radiant heat from the heat storage plate. In the meantime, the molten slag remaining in the slag outlet can be completely discharged from the slag outlet, and blockage of the slag outlet due to slag can be prevented.

〔Example〕

Embodiments of a melting furnace according to the present invention will be described below with reference to the drawings. 1 to 7 are views showing a swirl flow type melting furnace as an embodiment of the melting furnace according to the present invention. FIG. 1 is a schematic diagram of the swirl flow type melting furnace, and FIG.
The plan view of the swirling flow type melting furnace in the figure and FIGS. 3 to 6 are cross-sectional views taken along the line I-I in FIG. 1, showing heat storage bodies of different shapes (however, From figure 5
The support base 20 is not shown up to the figure), and FIG. 7 is a partial cross-sectional view showing an example of a mounting structure of the heat storage body.

As shown in FIG. 1, this swirl flow type melting furnace 1 is formed of a furnace body 1A made of a refractory, and mainly comprises swirling melting chambers 4 and 5 for performing swirling melting of a material to be melted, exhaust gas and molten slag. A heat storage for heating a slag outlet 15 arranged in the discharge passage, and a discharge passage including a flue gas passage 9 for discharging the flue gas EG upward and a slag outlet 10 for discharging the molten slag S downward. It is composed of body 21.

The material to be melted is not only waste such as sewage sludge dry matter, incineration residue, municipal waste incineration residue, etc., but also pulverized coal, solid fuel containing unburned carbon, etc. These materials to be melted are swirling flow type melting furnaces. Is melt processed.

The swirling and melting chamber may have a single stage or a plurality of stages. For example, when the swirling and melting chamber is configured in two stages, the first stage swirling and melting chamber 4 has a melted material supply port 13 and a combustion air blowing port 2 at the upper part of the cylindrical portion. Arranged in a tangential direction, a swirling air flow of the material to be melted is formed in the furnace to perform combustion melting. Further, an auxiliary combustion burner 6 is provided in the upper part of the first stage swirl melting chamber 4 in the tangential direction of the cylindrical portion. In the lower part of the first-stage swirling and melting chamber 4, a throttle portion 12 constituted by an inclined surface whose furnace inner diameter is gradually reduced in the outlet direction is provided at the outlet in order to enhance the collection efficiency of the molten slag. Further, a second stage swirl melting chamber 5 having a cylindrical portion inclined with respect to the lower part is connected to a lower portion of the first stage swirl melting chamber 4, and an outlet 11 of the first stage swirl melting chamber 4 and a second stage Swirl melting chamber 5
It communicates with the entrance 18 of the.

Further, in the second-stage swirl melting chamber 5, a combustion air blowing port 3 is arranged tangentially. The second-stage swirling and melting chamber 5 has an inclined surface 17 which is inclined and extends downward, and a lower portion of the inclined surface 17 is formed with a throttle portion 16 whose inner diameter is gradually reduced in the outlet direction by the inclined surface. The throttle portion 16 is connected to the exhaust gas passage 9 located above and the slag discharge port 10 located below. In addition, in the upper part of the second stage swirling melting chamber 5,
The auxiliary combustion burner 7 is provided in the tangential direction of the cylindrical portion.

By adopting the two-stage swirl combustion system as described above, this melting furnace 1 enhances the separation efficiency of the exhaust gas and the slag, and the two-stage arrangement allows the lower part of the first-stage swirl melting chamber 4, that is, the swirl melting chamber outlet 11 to be formed. Has a structure capable of receiving radiant heat from the second-stage swirling and melting chamber 5.

At the slag outlet 15 which is the outlet of the second stage swirling and melting chamber 5, conventionally, as described above, solidification and deposition of the molten slag occur due to the temperature decrease, which causes remarkable difficulty in the furnace operation. For, the exhaust gas passage 9 is divided,
The heat storage body 21 that covers the slag outflow wall surface 23 is installed to accelerate the heating of the molten slag, thereby preventing the slag outlet 15 from being blocked.

The heat storage body 21 is for storing and radiating radiant heat from the molten slag during the operation of the melting furnace, and may be a general refractory material such as refractory bricks and refractory castables, but is preferably heat-resistant with high specific heat such as stainless steel. It is made of a flexible material. The heat storage body 21, for example, the temperature of the slag outlet 15 portion due to the radiant heat from the heat storage body 21 even when a situation in which the temperature in the melting furnace sharply decreases due to changes in the properties of the material to be melted or operating conditions Kept high, slag outlet 15
It is possible to prevent the blockage due to the slag. Further, even if the molten slag still remains in the melting furnace immediately after the operation of the melting furnace is stopped, the temperature of the slag outlet 15 part is kept high for a while by the radiant heat from the heat storage body 21. Therefore, in the meantime, the molten slag remaining in the slag outlet 15 can be completely discharged from the slag outlet 15 to the slag outlet 10, and the slag outlet 15 can be prevented from being blocked.

As a mounting position of the heat storage body 21, the slag outflow wall surface 23 is defined so that the exhaust gas flow path 9 is divided into the exhaust gas flow path 9 and the slag outflow wall surface 23 is brought into contact with the slag outflow wall surface 23. It is preferably arranged so as to cover. By arranging in this way, the heat storage body 21 can be connected to the slag outlet.
It is possible to suppress heat radiation to the outside in the 15th part, prevent the temperature of the exhaust gas from lowering, and effectively keep the slag outlet 15 and the molten slag warm.

The shape of the heat storage body 21 may be a roof shape as shown in FIG. 3, or may be a box shape as shown in FIG. 4 in order to suppress the short path of the molten mist.

Further, in the case of the box shape, since molten mist may be accumulated on the corner portion 24, it is preferable to form a saddle shape having a curved surface as shown in FIG. That is, the heat storage body 21 is composed of two leg portions 211 and 212 and a curved neck portion 213 that connects both leg portions 211 and 212.

The heat storage body 21 is attached to the furnace body 1A by embedding and fixing it in the furnace body 1A when manufacturing the furnace body 1A. For example, as shown in FIG.
A pair of protrusions 211E extending from the lower end of 1 (a protrusion extending from the lower end of the leg 212 is not shown) and a pair of protrusions 213E extending from the top 213 are formed, and these protrusions are connected to the furnace body 1A.
It is arranged around the slag outlet 15 and embedded and joined. Note that these protrusions need not necessarily be provided in pairs.

The heat storage body 21 may be directly attached to the furnace body 1A as described above, but in consideration of the fact that the size thereof is elongated due to a thermal change in the initial operation, and if it is damaged, it is difficult to restore it. As shown in FIG. 1 and FIG. 6, when the furnace body 1A is not joined to the furnace body 1A, it is embedded in the furnace body 1A and mounted on the joined support body 20 so that the furnace body 1A can be detached at any time. Good.

In this swirl flow type melting furnace 1 configured as described above,
For example, when treating the dried sewage sludge, which is the material to be melted, first, the combustion gas such as heavy oil is burned by the auxiliary combustion burners 6 and 7 into the first stage swirling melting chamber 4 and the second stage swirling melting chamber 5. And the temperature of the swirling and melting chambers 4 and 5 is raised. In this case, since the auxiliary combustion burners 6 and 7 are respectively arranged in the tangential direction of the cylindrical swirling melting chamber, the first stage swirling melting chamber 4
In addition, a swirling airflow due to the combustion gas is formed in the second stage swirling and melting chamber 5. By raising the temperature, the temperature of each swirling melting chamber 4,5,
After the ash content of the sludge is melted and the temperature of the melt is raised to a temperature suitable for flowing in the furnace, the sludge dried material is fed to the melted material supply port.
Blow from 13 into the first stage swirl melting chamber 4 from the tangential direction. At the same time, about 1.05 to 1.40 times the theoretical air amount of sludge is supplied to the combustion air blowing port 2 of the first stage swirling and melting chamber 4, for example.
50 to 80% of the total amount of air, and the remaining air from the combustion air blowing port 3 of the second stage swirling and melting chamber 5 into the melting chambers 4 and 5, respectively.
It controls so that it blows tangentially with respect to 5.

The sludge dried matter blown into the first stage swirling and melting chamber 4 instantaneously undergoes space combustion under high temperature while riding on a high-speed swirling air flow formed by the carrier air, the sludge combustion air, and the burner combustion gas.
However, some of the large particles still remain unburned, receive a strong centrifugal force and collide with the furnace wall surface, and are captured by the molten slag layer and burned. The ash content in the sludge is melted, and most of it melts down along the furnace wall surface, but part of it becomes molten mist and is guided to the second-stage swirl melting chamber 5 while being entrained with the combustion gas.

In the second stage swirling and melting chamber 5, in the case of the remaining combustion air and sludge having a low calorific value, the combustion gas from the auxiliary combustion burner 7 is blown from the tangential direction to form a strong swirling airflow again. Here, while the unburned gas that remains partially burns completely and raises the temperature of the second-stage swirling melting chamber 5, the molten material collides with the furnace wall surface and is collected by the cyclone effect of the swirling air flow. Separation of gas and melt is promoted, and the collection rate of molten slag can be increased.

In the second-stage swirling and melting chamber 5, the melt collected on the wall surface of the furnace flows down while forming a pool on the lower surface of the cylinder, and while being heated by the heat storage body 21, drops into the slag discharge port 10, It is thrown into the slag receiver arranged at the discharge port 10.

At that time, since the heat storage body 21 is arranged so as to form a gas passage in the exhaust gas flow path 9, it is possible to prevent heat in the slag outlet 15 from being radiated to the outside and prevent a decrease in gas temperature. To do. In this way, since the heating of the molten slag is promoted by the heat storage body 21, the molten slag is maintained at a temperature higher than the melting temperature of the slag at the slag discharge port 15, and the molten slag is solidified at the slag outlet. It does not accumulate and block the outlet.

On the other hand, the exhaust gas separated from the melt is exhausted from the exhaust gas passage 9. The exhaust gas exhausted from the exhaust gas passage 9 is sent to the heat exchanger through, for example, the third-stage combustion chamber arranged in the downstream, and the exhaust gas is heat-exchanged to recover the thermal energy, and then transferred to the cyclone. Sent in. After the gas and solids of the exhaust gas are separated by the cyclone, the gas component is further sent to a bag filter and completely separated.

In addition, as shown in FIG. 7, the protrusions 2 are formed on the legs 211 of the heat storage body 21.
11E, a protrusion 213E is provided on the top (not shown, but leg 2
12 also have protrusions), and these protrusions are connected to the slag outlet 15
When it is embedded so as to be placed around the slag, the slag outlet 15 part can retain the high temperature more efficiently due to the heat conduction transferred from these protrusions to the inner surface of the slag outlet 15 in addition to the radiant heat. it can.

Next, the results of performance comparison experiments of the swirling flow type melting furnace 1 with the heat storage body 21 according to the present invention and the conventional swirling flow type melting furnace 1 without the heat storage body 21 will be described.

The first-stage swirl / melting chamber 4 has an inner diameter of 350 mmφ and an effective height of 130
A cylinder having a diameter of 350 mm and a length of 1200 mm was used as the second-stage swirl melting chamber 5. A cylinder of the second-stage swirling melting chamber 5 is connected to the lower part of the cylinder of the first-stage swirling melting chamber 4 with an inclination of 15 °, and a saddle-shaped heat storage is provided above the end of the slag outlet of the second-stage swirling melting chamber. The body 21 was arranged to form a swirl flow type melting furnace. After the temperature of the first-stage swirling melting chamber 4 and the second-stage swirling melting chamber 5 was raised from 1200 ° C to 1400 ° C by the auxiliary combustion burner, the dehydrated cake of sewage sludge was treated with an airflow dryer to remove water. To 20% of the dried product was supplied to the upper part of the first stage swirling and melting chamber 4 by pneumatic transportation. Burning air
The sludge air ratio was set to 1.1 to 1.3, and about 70% of the total amount was split-injected into the first-stage swirl melting chamber 4 and about 30% into the second-stage swirl melting chamber 5. While maintaining the temperature of each swirl melting chamber from 1200 ℃ to 1400 ℃, the amount of auxiliary combustion burner oil was decreased and the supply amount of drying was increased, and the natural operation was performed with the supply amount of 35 to 45kg DS / h. .

Table 1 shows the results obtained by continuing the experiment for about 2 months. As is clear from Table 1, as a result of a melting experiment using this swirl-flow type melting furnace, there was no particular trouble in the operation of the furnace, and a slag collection rate of 95% or more was obtained for about 2 months. It was obtained stably. Here, the slag collection rate R is the recovered slag weight W
Is the value of the percentage obtained by dividing by the conversion weight C of the supplied sludge.

That is, R = 100 × W / C.

As an example, the result when the heating plate was not installed at the slag outlet of the second stage swirling melting chamber and the treatment was performed for about 2 months using the swirling type melting furnace exactly the same as this experiment, was the same. Table 1
However, there was a phenomenon in which the temperature drop at the outlet of the second-stage swirling melting chamber was large, the viscosity of the molten slag increased, and the flow-down state deteriorated. Then, a phenomenon was observed in which the molten slag was solidified and accumulated in a part of the flow path to obstruct the flow down.

Although one example of the melting furnace according to the present invention has been described by taking the swirl flow type melting furnace as an example, other types of melting furnace include a burner method, an electric furnace method, a rotating film melting method, a plasma torch method, and the like. Needless to say, the present invention is applicable to any known method.

[Effects of the Invention] The melting furnace according to the present invention is configured as described above and has the following effects.

In this melting furnace, at the slag outlet of the melting furnace main body, the exhaust gas flow path is divided, and the heat storage body is installed in the discharge passage for discharging the exhaust gas and the molten slag, so that the molten slag at the slag outlet of the melting furnace is It always flows in a very stable state by maintaining a molten state. For this reason, molten slag will not solidify and accumulate to block the slag outlet, and work to remove the solidified and accumulated slag, damage to the furnace material due to that work, and repair work in that case will not be necessary at all. Not only that, but also because it is not necessary to temporarily stop the operation of the melting furnace for the slag removal work, the operation efficiency is significantly improved.

Also, since the heat storage body can be installed in the discharge passage to keep the temperature at the slag outlet high, the particles of the melted object burn more efficiently, and the unburned particles discharged from the melting furnace together with the gas. Is equal to nothing. Therefore, the slag collection rate becomes higher than that of the conventional melting furnace in which the heat storage body is not installed. If the slag collection rate is high, it means that the melted matter is completely separated into slag and exhaust gas, and there is no frictional contact of unburned particles or molten components with the wall surface of the exhaust gas passage. Erosion and melting will not occur.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the melting furnace according to the present invention, FIG. 2 is a plan view of the melting furnace of FIG. 1, FIG. 3, and FIG.
FIGS. 5, 5 and 6 are cross-sectional views taken along line I-I of FIG. 1 showing different examples of the heat storage bodies arranged in the melting furnace of FIG. 1, and FIG. 7 shows the melting furnace of FIG. FIG. 8 is a partial cross-sectional view showing another example of the arranged heat storage body, and FIG. 8 is a schematic view showing an example of a conventional melting furnace. 1 ... Swirl flow type melting furnace, 4 ... First stage swirling melting chamber, 5 ...
… Second stage swirling melting chamber, 9 …… Exhaust gas flow path (exhaust passage),
10 …… Slag discharge port (discharge passage), 15 …… Slag outlet, 21 …… Heat storage body.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shin Sasaki 1-6-27 Konan, Minato-ku, Tokyo Ebara Infilco Co., Ltd. (56) References JP-A-50-101276 (JP, A) 60-86731 (JP, U)

Claims (1)

[Claims] 1. A melting chamber for melting a material to be melted, a melted material supply port for supplying the material to be melted to the melting chamber, a slag outlet which is an outlet of the melting chamber, and a slag outlet. A discharge passage consisting of an exhaust gas flow path for discharging exhaust gas and a slag discharge port for discharging slag, and the slag flow for holding thermal energy received from the molten slag and the exhaust gas with respect to the slag outlet and the slag discharge port A melting furnace having a heat storage body arranged in the discharge passage near the outlet.