JPH0336412A - Revolving melting furnace of multi-stage type - Google Patents

Abstract

PURPOSE:To keep molten components from solidifying and piling up and discharge them smoothly from each revolving melting chamber by providing a first stage revolving melting chamber provided with a charging port for objects to be melted and an air port into which the combustion air is blown in and a second stage revolving melting chamber provided with an air port into which the combustion air is blown in and arranging both revolving melting chambers so as to have communication between them. CONSTITUTION:A first stage revolving melting chamber 4 has a cylindrical section and at its upper section a charging port 13 for objects to be melted and an air port 2 into which the combustion air is blown in, both port 13 and port 2 being located in the direction of a tangential line to the cylindrical section in order to form a revolving air flows for the objects to be melted in the melting chambers and melt them by combustion. Below this first stage revolving melting chamber 4 an outlet throttling section 11 is provided which is constituted of an inclining face 12 with its inner diameter gradually reduced, and a second stage revolving melting chamber 5 is connected which has a downwardly inclining cylindrical section. Its inlet section 18 communicates with the outlet throttling section 11. Further, to be second stage revolving melting chamber 5 an air port 3 into which the combustion air is blown is provided in the direction of a tangential line to the melting chamber 5. With this multistage arrangement the outlet throttling section 11 receives radiation heat from the second stage revolving melting chamber 5 so that there is almost no solidification of the objects to be melted and they are discharged smoothly.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a method of melting and solidifying natural substances by burning combustible components, that is, materials to be melted, contained in dried sewage sludge, incineration residue, municipal waste incineration residue, etc. This invention relates to a multi-stage rotary melting furnace that can produce slag.

[Conventional technology]

In recent years, the amount of waste generated such as sewage sludge and municipal waste incineration residue has been increasing year by year, and it has become increasingly difficult to secure landfill sites. In addition, mercury, copper, and Cr contained in waste.

The risk of contamination due to the elution of harmful heavy metals such as Cd has been raised as a long-term problem. In waste treatment, volume reduction and detoxification of the negative layer have become important issues. Therefore, swirling melting furnaces have attracted attention as a new technology that can address such waste disposal problems.

This swirling melting furnace is, for example, a single-stage swirling melting furnace, as shown in FIG. It is arranged in the tangential direction of the furnace body 24, and an auxiliary fuel supply port 23 is provided at the top.
A slag discharge port 27 is provided at the lower part of the furnace body 24, and a slag receiver (not shown) is replaceably installed in the slag discharge port 27. Further, an exhaust gas outlet 26 is formed that extends to the lower side of the furnace body 24, and the exhaust gas outlet 26 is connected to, for example, a heat exchanger, a cyclone, a bag filter, etc., so that the exhaust gas generated in the furnace body 24 is treated. It is configured to

In such a swirling melting furnace, for example, when treating dried sewage sludge, the dried sewage sludge is first injected into the furnace from the upper part of the furnace body 24 along the flow of combustion air that swirls strongly. . This swirling flow causes centrifugal force to act on the dried particles, causing separation of fine particles and coarse particles, and the fine particles can be combusted in a short period of time together with the volatile matter in a suspended state.
Coarse particles are deposited on the surface of the molten slag that forms on the inner wall of the furnace.
By promoting efficient combustion, a high furnace load can be achieved. Therefore, the combustion heat of the sludge makes it possible to maintain the inside of the furnace at a high temperature, and ash content is melted simultaneously with combustion. The molten material is collected on the furnace wall surface, flows down into the furnace while forming a slag surface, is taken out from the slag discharge port 27 in the lower part of the furnace, and is cooled and solidified.

Molten slag has a specific gravity 3 to 5 times greater than general incineration ash, and can be significantly reduced in volume. In addition, since harmful heavy metals can be fixed in the slag, there is no problem with leaching, and due to its physical properties, it can be expected to be recycled as a resource for construction aggregates, road grindstones, etc. In this way, the swirling melting furnace can effectively use the heat generated by the combustibles in the waste to melt the ash, making it possible to significantly reduce the need for auxiliary fuel and melting aids, making it an economically superior device. As such, it can deal with the problem of wild boars in waste disposal.

[Problem to be solved by the invention]

By the way, in the conventional single-stage swirling melting furnace, in order to improve the slag collection efficiency, as shown in FIG.
The structure has been devised to promote the capture of unburned particles and molten material on the slag surface that flowed out with the gas.

However, since the outlet constriction part 25 and the lower slag discharge port 27 of the furnace body 24 are configured to be separated from the main combustion zone A of the furnace body 24, the sewage sludge introduced into the furnace from the upper part of the furnace body 24 Depending on the material to be melted and the operating conditions, the material to be melted such as dried material may be sent to the slag discharge port 27 in an insufficient combustion state, that is, in a molten state. Depending on the properties and operating conditions of the material to be melted, the slag may be discharged with the remaining molten components remaining, or depending on the properties of the material to be melted and operating conditions, the core molten components may reach the lower outlet constriction section 25 and the slag may reach the slag melting temperature. There was a risk that the solidified material to be melted would accumulate on the furnace wall surface, narrowing the gas flow path in the outlet constriction section 25, and eventually blocking it. Slag blockage causes significant fluctuations in the furnace pressure and makes it difficult for the slag to flow out, making it impossible to operate the swirling melting furnace. In addition, since the accumulated slag is solidified integrally with the furnace material constituting the melting furnace, it is not easy to remove it.

Furthermore, when the separation efficiency between slag and exhaust gas deteriorates, high-speed gas accompanied by unburned particles and melted materials is discharged through the exhaust gas outlet 26, causing frictional contact with the furnace wall and passage wall downstream. Severe abrasion of the wall surface may occur, resulting in erosion and melting of the furnace material. Therefore, large-scale construction work is required to repair the furnace material, and if damage occurs frequently, it may be fatal to the swirling flow melting furnace.

The purpose of this invention is to solve the above-mentioned problems in the rotary melting furnace. The chambers are provided in multiple stages, and the melted material is smoothly flowed without solidifying in the first-stage rotating melting chamber and the second-stage rotating melting chamber,
It prevents the molten components in the melted material from solidifying and accumulating at each exit constriction section, and allows the material to be melted and discharged smoothly from each rotating melting chamber, allowing stable melting and separation of the melted material. An object of the present invention is to provide a multi-stage swirling melting furnace.

[Means to solve the problem]

In order to solve the above object, the present invention is configured as follows. That is, the present invention provides a first stage having a melt supply port and a combustion air inlet opening in the tangential direction of the cylindrical portion at the upper part, and an outlet throttle section at the lower part where the cylindrical part is made smaller by an inclined surface. a swirling melting chamber, a combustion air inlet opening in the tangential direction of the cylindrical portion and the inlet portion which is arranged at an angle with respect to the first stage swirling melting chamber and communicates with the outlet constriction portion, and the cylindrical portion; The present invention relates to a multi-stage swirling melting furnace comprising a second stage swirling melting chamber equipped with a lower part of the outlet constriction section formed by a small inclined surface, and combustion burners disposed at the upper part of each of the swirling melting chambers.

[Effect]

The multi-stage swirling melting furnace according to the present invention is constructed as described above and operates as follows.

That is, this multi-stage swirling melting furnace has a first stage swirling melting chamber equipped with a melting material supply port and a combustion air inlet opening in the tangential direction, a combustion air blowing port, and an exit constriction portion configured to be small by an inclined surface. , a second-stage swirling melting chamber having an outlet constriction section at a lower portion configured to be small by a combustion air inlet and an inclined surface arranged at an angle with respect to the outlet constriction section of the nuclear melting chamber and provided in a tangential direction; Since the combustion burner is arranged at the upper part of each of the swirling melting chambers, a second stage swirling melting chamber having a cylindrical shape inclined to the lower part is connected to adopt a two-stage swirling method. The separation efficiency of exhaust gas and slag can be increased and the collection efficiency can be improved, and with this structure, each of the outlet constrictions is provided at the lower part of the first stage swirling melting chamber and the lower part of the second stage swirling melting chamber. Therefore, by appropriately adjusting the degree of the slope of the outlet constriction part, the residence time of the material to be melted in the first-stage swirling melting chamber and the second-stage swirling melting chamber can be adjusted. In addition to sufficiently melting the material itself, centrifugal force acts to achieve sufficient separation of fine particles and coarse particles.The fine particles can be burned in a suspended state together with the volatile matter in a short time, and the coarse particles can be burned on the inner wall of the furnace. The molten slag is trapped on the surface of the molten slag that forms, and a suitable combustion time is given for combustion, allowing efficient combustion and achieving a high furnace load.

Further, since the second stage swirling melting chamber is located below the outlet constriction part of the first stage swirling melting chamber, the first stage swirling melting chamber receives radiant heat from the second stage swirling melting chamber. There is almost no solidification of the material to be melted at the outlet constriction section, and the material to be melted is smoothly fed into the second stage swirling melting chamber and is further completely combusted. is inclined, so the slag smoothly flows down and reaches the outlet constriction, and the exhaust gas flows down from the outlet constriction to the slag discharge port and the exhaust gas flows through the outlet constriction of the second stage swirling melting chamber. from the exhaust gas outlet to the exhaust gas outlet. Therefore, since the material to be melted is completely separated into slag and exhaust gas, there are no unburned particles or molten components in the exhaust gas, and the exhaust gas is not exposed to the wall surface of the exhaust gas passage. There is no frictional contact between unburned particles and molten components, and no corrosion or melting of the furnace material occurs.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a multi-stage rotating melting furnace according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a multi-stage rotating melting furnace according to the present invention, and FIG. 2 is a plan view of the multi-stage rotating melting furnace shown in FIG.

As shown in FIG. 1, a multi-stage rotating melting furnace I according to the present invention
It mainly consists of a first-stage swirling melting chamber 4 for burning and melting the material to be melted, a second-stage swirling melting chamber 5, an exhaust gas outlet 9 for separating and discharging exhaust gas and molten slag, and a slag discharge port 10. ing.

Further, although not shown, a replaceable slag receiver is installed below the slag discharge port 10. Further, an exhaust gas outlet 9 extending upward from the side of the rotating melting furnace 1 is connected to, for example, a heat exchanger, a cyclone, a bag filter, etc., and the exhaust gas generated in the rotating melting furnace 1 is configured to be treated. . Materials to be melted include wastes such as dried sewage sludge, incineration residue, municipal waste incineration residue, etc., as well as solid fuels containing Huai charcoal and unburned carbon. It is effectively melted in a multi-stage rotating melting furnace.

The first stage swirling melting chamber 4 has a cylindrical part, and a supply port 13 for the material to be melted and a combustion air blowing port 2 are arranged in the tangential direction of the cylindrical part in the upper part, and the material to be melted is swirled in the chamber. The lower part of the first-stage swirling melting chamber 4, which forms an air flow to perform combustion melting, has an inclined surface whose inner diameter gradually decreases toward the outlet in order to increase the efficiency of collecting molten slag. 12 is provided. Furthermore, an auxiliary combustion burner 6 is provided in the upper part of the first-stage rotating melting chamber 4 in the tangential direction of the cylindrical portion. This auxiliary combustion burner 6
may be provided by being inserted from the part indicated by numeral 8, but here, the part indicated by numeral 8 is provided with a peephole. Further, the lower part of the first-stage swirling melting chamber 4 is connected to the second-stage swirling melting chamber 5 having a cylindrical part inclined with respect to the lower part, and the outlet constriction part 11 of the first-stage swirling melting chamber 4 and the second-stage swirling melting chamber 5 are connected to each other. Inlet part 18 of two-stage swirling melting chamber 5
It communicates with

Furthermore, a combustion air inlet 3 is arranged tangentially in the second stage swirling melting chamber 5 . The second-stage rotating melting chamber 5 has an inclined surface 17 that extends downwardly.
An exit throttle section 15 is formed in the lower part of the furnace by an inclined surface 16, and the inner diameter of the furnace is gradually reduced in the exit direction. This outlet constriction part 15 is connected to the exhaust gas outlet 9 located above and the slag discharge port 10 located below. Also, the second
An auxiliary combustion burner 7 is provided in the upper part of the staged rotating melting chamber 5 in the tangential direction of the cylindrical portion. The auxiliary combustion burner 7 may be installed by being inserted from the part indicated by the reference numeral 14, but here, the part indicated by the reference numeral 14 is provided with a viewing window.

The multi-stage rotating melting furnace 1 according to the present invention has two parts as described above.
By adopting the staged swirling combustion system, the separation efficiency of wandering gas and slag is increased, and this multistage arrangement allows the lower part of the first stage swirling melting chamber 4, that is, the outlet constriction section 11, to absorb the radiant heat from the second stage swirling melting chamber 5. The structure is such that it can receive the following.

In this multi-stage rotary melting furnace 1 configured as described above, for example, when processing dried sewage sludge as the material to be melted, first, combustion gas such as heavy oil is heated by the auxiliary combustion burner 6.7. The air is blown into the first-stage swirling melting chamber 4 and the second-stage swirling melting chamber 5 to raise the temperature of each swirling melting chamber 4, 5. In this case, each auxiliary combustion burner 6.7 is a cylindrical melting chamber. Since they are arranged in the tangential direction of the combustion gas, a swirling airflow is formed by the combustion gas in the first-stage swirling melting chamber 4 and the second-stage swirling melting chamber 5. 4. Each swirling melting chamber due to temperature increase. After raising the temperature in step 5 to a temperature suitable for melting the ash content of the sludge and causing the melt to flow in the furnace, the dried sludge is transferred from the dried sludge supply port 13 to the first stage rotating melting chamber. 4 from the tangential direction, and at the same time about 1.05 to 1.
40 times the amount of combustion air, for example, 50 to 80% of the total air amount from the combustion air inlet 2 of the first stage swirling melting chamber 4 and from the combustion air inlet 3 of the second stage swirling melting chamber 5. The remaining air is blown tangentially into the melting chamber 4.5.

At this time, it is necessary to adjust the amount of heavy oil combustion gas so that the temperature of each swirling melting chamber 4.5 does not rise excessively, but if the calorific value of the sludge is sufficiently large and the melting point of the ash is not extremely high. Since the melting temperature is appropriately maintained only by the combustion heat of the sludge, it is possible to completely stop each auxiliary combustion burner 6.7. Furthermore, since the auxiliary combustion burners 6, 7 can be operated separately, it is possible to select an auxiliary combustion method that suits the operating situation.

The dried sludge may be obtained by pulverizing the dried material from a hot air dryer or an indirect heating dryer, or may be the dried material from a flash dryer without being pulverized. It is sufficient that the dry material has properties that allow it to be supplied at a flow rate of 10 to 50 s/see. Normally, this dried material has a moisture content of 20% or less and a particle size of 1000 μ or less, but it is supplied from the sludge dry material supply port 13 to a swirling air stream. When a part of the fine particles in the dried material is separated from the swirling airflow formed by most of the particles, a stagnation layer may be formed on top of the swirling airflow. If this stagnant layer is formed in the upper part of the first-stage swirling melting chamber 4, it may deposit on the outlet of the auxiliary combustion burner 6 or cause deposits of unmelted ash to form on the furnace wall. It is preferable to provide at least one combustion air inlet 2 of the first-stage swirling melting chamber 4 above the dried sludge supply port 13 to prevent the formation of a stagnation layer of fine particles.

The dried sludge blown into the first-stage swirling melting chamber 4 is instantaneously combusted in space at a high temperature while riding the high-speed swirling airflow formed by the conveying air, sludge combustion air, and burner combustion gas.

However, some of the larger particles remain as unburned particles and collide with the furnace wall due to strong centrifugal force, where they are trapped in the molten slag layer and burned. The ash in the sludge is melted, and most of it flows down along the furnace wall surface, but some of it becomes molten mist and is guided to the second stage swirling melting chamber 5 while being accompanied by combustion gas.

In the second-stage swirling melting chamber 5, in the case of remaining combustion air and sludge with a low calorific value, combustion gas from the auxiliary combustion burner 7 is blown in from the tangential direction to form a strong swirling airflow again. At this point, some of the remaining unburned gas is completely combusted.
While increasing the temperature of the second-stage swirling melting chamber 5, the cyclone effect caused by the swirling air flow causes the melt to collide with the furnace wall and be collected, promoting separation of the gas and the melt and increasing the collection rate of molten slag. can be increased.

The main purpose of the second-stage swirling melting chamber 5 is to thoroughly separate the gas and the melt, so if there is no drop in temperature, an appropriate volume, preferably its effective volume, can be used for the first-stage swirling combustion. It is preferable that the volume of the chamber 4 is at least 50% or more.

In addition, since the viscosity of the melt may decrease depending on the operating conditions, the second stage rotating melting chamber 5 is not horizontal and the outlet constriction part 15 is positioned downward so that the inclination angle is about 5 degrees or more. In the second-stage rotating melting chamber 5, which is preferably formed to The slag is put into a slag receiver arranged at the discharge port 10. On the other hand, the exhaust gas separated from the melt is exhausted from the exhaust gas outlet 9. The exhaust gas exhausted from the exhaust gas outlet 9 is sent to a heat exchanger through, for example, a third-stage combustion chamber arranged downstream, and the exhaust gas is heat-exchanged and thermal energy is recovered, and then transferred to a cyclone. sent.

After the exhaust gas is separated into gas and solids by the cyclone,
The gas is further sent to a bag filter where it is completely separated.

〔Effect of the invention〕

The multi-stage rotating melting furnace according to the present invention is constructed as described above, and has the following effects.

That is, this multi-stage swirling melting furnace is provided with a melting material supply port and a combustion air inlet opening in the tangential direction of the cylindrical portion at the top, and an outlet constriction portion where the cylindrical portion is made smaller by an inclined surface at the bottom. a first stage swirling melting chamber, a combustion air inlet opening in the tangential direction of the cylindrical part and the inlet part which is arranged at an angle with respect to the first stage swirling melting chamber and communicates with the outlet constriction part; and a second-stage swirling melting chamber, which is equipped with an outlet constriction section in the lower part in which the cylindrical section is made smaller by an inclined surface, and each combustion burner installed at the upper part of each of the swirling melting chambers, so that the lower part of the cough The separation efficiency of exhaust gas and slag can be increased by connecting the cylindrical second-stage rotating melting chamber that is inclined with respect to the first stage and adopting a two-stage swirling method. Since each of the outlet throttle parts is provided at the lower part of the 1st stage swirling melting chamber and the lower part of the 2nd stage swirling melting chamber, by appropriately adjusting the degree of the slope of the outlet throttle part, the 1st stage swirling melting chamber and the 2nd stage swirling melting chamber The residence time of the material to be melted in the second-stage rotating melting chamber can be adjusted, and the material to be melted is sufficiently melted, and centrifugal force acts on it.
Separation of fine particles and coarse particles is sufficiently achieved, fine particles can be combusted in a suspended state together with volatile matter in a short time, and coarse particles are captured on the molten slag surface forming on the inner wall of the furnace, making it suitable for combustion. Combustion time is given, combustion can be performed efficiently, and a high furnace load can be achieved.

Further, since the second stage swirling melting chamber is located below the outlet constriction part of the first stage swirling melting chamber, the first stage swirling melting chamber receives radiant heat from the second stage swirling melting chamber. There is almost no solidification of the material to be melted at the outlet constriction section, and the material to be melted is smoothly fed into the second stage swirling melting chamber and is further completely combusted. Since the is inclined, the slag smoothly flows down to the outlet constriction section, flows down from the outlet constriction section to the slag discharge port, and the exhaust gas flows through the outlet constriction section of the second stage swirling melting chamber. is exhausted from the exhaust gas outlet.

Therefore, the combustible components contained in dried sewage sludge, incineration residue, municipal waste incineration residue, etc. can be burned more efficiently, and the material to be melted can always flow smoothly and be discharged from the melting furnace, resulting in stable melting and separation processing. This makes it possible to melt and process waste materials extremely efficiently and stably. In addition, since the material to be melted is completely separated into slag and exhaust gas,
There are no unburned particles or molten components in the exhaust gas, and there is no frictional contact between unburned particles or molten components against the wall of the exhaust gas passage as in the past.
No erosion or melting of the furnace material occurs due to abrasion of the wall surface by the high-velocity gas.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a multi-stage rotating melting furnace according to the present invention, FIG. 2 is a plan view of the multi-stage rotating melting furnace shown in FIG. 1, and FIG. FIG. 1-・-・・・・Multi-stage rotating melting furnace, 2.3-・・・・・
・・Combustion air inlet, 4-・−・1st stage swirling melting chamber,
5--Second-stage rotating melting chamber, 6.7--Auxiliary combustion burner, 9--Exhaust gas outlet, 10.
......-Slag discharge port, 11゜15...-Outlet throttle section, 13...Dry sludge supply port, 17...
・−・・Slope, 18・−・−・Population Department.

Claims (1)

[Claims] A first-stage rotating melting chamber comprising a melting material supply port and a combustion air inlet opening in the tangential direction of the cylindrical part at the upper part, and an outlet constriction part at the lower part in which the cylindrical part is made smaller by an inclined surface; A combustion air inlet opening in the tangential direction of the cylindrical part and the inlet part that is arranged at an angle with respect to the first-stage swirling melting chamber and communicates with the outlet constriction part is formed in the upper part, and the cylindrical part is made small by an inclined surface. The second outlet is equipped with an outlet constriction section at the bottom.
A multi-stage swirling melting furnace comprising a stage swirling melting chamber and combustion burners respectively disposed above each of the swirling melting chambers.